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6938 lines
257 KiB
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6938 lines
257 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<title>LLVM Assembly Language Reference Manual</title>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="author" content="Chris Lattner">
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<meta name="description"
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content="LLVM Assembly Language Reference Manual.">
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<link rel="stylesheet" href="llvm.css" type="text/css">
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</head>
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<body>
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<div class="doc_title"> LLVM Language Reference Manual </div>
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<ol>
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<li><a href="#abstract">Abstract</a></li>
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<li><a href="#introduction">Introduction</a></li>
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<li><a href="#identifiers">Identifiers</a></li>
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<li><a href="#highlevel">High Level Structure</a>
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<ol>
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<li><a href="#modulestructure">Module Structure</a></li>
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<li><a href="#linkage">Linkage Types</a></li>
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<li><a href="#callingconv">Calling Conventions</a></li>
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<li><a href="#namedtypes">Named Types</a></li>
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<li><a href="#globalvars">Global Variables</a></li>
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<li><a href="#functionstructure">Functions</a></li>
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<li><a href="#aliasstructure">Aliases</a></li>
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<li><a href="#paramattrs">Parameter Attributes</a></li>
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<li><a href="#fnattrs">Function Attributes</a></li>
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<li><a href="#gc">Garbage Collector Names</a></li>
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<li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
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<li><a href="#datalayout">Data Layout</a></li>
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</ol>
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</li>
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<li><a href="#typesystem">Type System</a>
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<ol>
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<li><a href="#t_classifications">Type Classifications</a></li>
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<li><a href="#t_primitive">Primitive Types</a>
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<ol>
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<li><a href="#t_floating">Floating Point Types</a></li>
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<li><a href="#t_void">Void Type</a></li>
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<li><a href="#t_label">Label Type</a></li>
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</ol>
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</li>
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<li><a href="#t_derived">Derived Types</a>
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<ol>
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<li><a href="#t_integer">Integer Type</a></li>
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<li><a href="#t_array">Array Type</a></li>
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<li><a href="#t_function">Function Type</a></li>
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<li><a href="#t_pointer">Pointer Type</a></li>
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<li><a href="#t_struct">Structure Type</a></li>
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<li><a href="#t_pstruct">Packed Structure Type</a></li>
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<li><a href="#t_vector">Vector Type</a></li>
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<li><a href="#t_opaque">Opaque Type</a></li>
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</ol>
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</li>
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<li><a href="#t_uprefs">Type Up-references</a></li>
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</ol>
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</li>
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<li><a href="#constants">Constants</a>
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<ol>
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<li><a href="#simpleconstants">Simple Constants</a></li>
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<li><a href="#aggregateconstants">Aggregate Constants</a></li>
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<li><a href="#globalconstants">Global Variable and Function Addresses</a></li>
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<li><a href="#undefvalues">Undefined Values</a></li>
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<li><a href="#constantexprs">Constant Expressions</a></li>
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</ol>
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</li>
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<li><a href="#othervalues">Other Values</a>
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<ol>
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<li><a href="#inlineasm">Inline Assembler Expressions</a></li>
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</ol>
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</li>
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<li><a href="#instref">Instruction Reference</a>
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<ol>
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<li><a href="#terminators">Terminator Instructions</a>
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<ol>
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<li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
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<li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
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<li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
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<li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
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<li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
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<li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#binaryops">Binary Operations</a>
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<ol>
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<li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
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<li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
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<li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
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<li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
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<li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
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<li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
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<li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
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<li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
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<li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#bitwiseops">Bitwise Binary Operations</a>
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<ol>
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<li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
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<li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
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<li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
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<li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
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<li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
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<li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#vectorops">Vector Operations</a>
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<ol>
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<li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
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<li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
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<li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#aggregateops">Aggregate Operations</a>
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<ol>
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<li><a href="#i_extractvalue">'<tt>extractvalue</tt>' Instruction</a></li>
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<li><a href="#i_insertvalue">'<tt>insertvalue</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#memoryops">Memory Access and Addressing Operations</a>
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<ol>
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<li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
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<li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
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<li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
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<li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
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<li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
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<li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#convertops">Conversion Operations</a>
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<ol>
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<li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
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<li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
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<li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
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<li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
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<li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
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<li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
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<li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
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<li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
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<li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
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<li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
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<li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
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<li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
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</ol>
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</li>
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<li><a href="#otherops">Other Operations</a>
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<ol>
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<li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
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<li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
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<li><a href="#i_vicmp">'<tt>vicmp</tt>' Instruction</a></li>
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<li><a href="#i_vfcmp">'<tt>vfcmp</tt>' Instruction</a></li>
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<li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
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<li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
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<li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
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<li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
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</ol>
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</li>
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</ol>
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</li>
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<li><a href="#intrinsics">Intrinsic Functions</a>
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<ol>
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<li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
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<ol>
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<li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
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<li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
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<li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
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</ol>
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</li>
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<li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
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<ol>
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<li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
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<li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
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<li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
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</ol>
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</li>
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<li><a href="#int_codegen">Code Generator Intrinsics</a>
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<ol>
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<li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
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<li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
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<li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
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<li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
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<li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
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<li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
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<li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
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</ol>
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</li>
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<li><a href="#int_libc">Standard C Library Intrinsics</a>
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<ol>
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<li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
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<li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
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<li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
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<li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
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<li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
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<li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
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<li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
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<li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
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</ol>
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</li>
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<li><a href="#int_manip">Bit Manipulation Intrinsics</a>
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<ol>
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<li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
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<li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
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<li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
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<li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
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<li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
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<li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
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</ol>
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</li>
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<li><a href="#int_overflow">Arithmetic with Overflow Intrinsics</a>
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<ol>
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<li><a href="#int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt> Intrinsics</a></li>
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<li><a href="#int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt> Intrinsics</a></li>
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<li><a href="#int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt> Intrinsics</a></li>
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<li><a href="#int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt> Intrinsics</a></li>
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<li><a href="#int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt> Intrinsics</a></li>
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</ol>
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</li>
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<li><a href="#int_debugger">Debugger intrinsics</a></li>
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<li><a href="#int_eh">Exception Handling intrinsics</a></li>
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<li><a href="#int_trampoline">Trampoline Intrinsic</a>
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<ol>
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<li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
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</ol>
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</li>
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<li><a href="#int_atomics">Atomic intrinsics</a>
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<ol>
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<li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
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<li><a href="#int_atomic_cmp_swap"><tt>llvm.atomic.cmp.swap</tt></a></li>
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<li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
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<li><a href="#int_atomic_load_add"><tt>llvm.atomic.load.add</tt></a></li>
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<li><a href="#int_atomic_load_sub"><tt>llvm.atomic.load.sub</tt></a></li>
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<li><a href="#int_atomic_load_and"><tt>llvm.atomic.load.and</tt></a></li>
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<li><a href="#int_atomic_load_nand"><tt>llvm.atomic.load.nand</tt></a></li>
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<li><a href="#int_atomic_load_or"><tt>llvm.atomic.load.or</tt></a></li>
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<li><a href="#int_atomic_load_xor"><tt>llvm.atomic.load.xor</tt></a></li>
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<li><a href="#int_atomic_load_max"><tt>llvm.atomic.load.max</tt></a></li>
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<li><a href="#int_atomic_load_min"><tt>llvm.atomic.load.min</tt></a></li>
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<li><a href="#int_atomic_load_umax"><tt>llvm.atomic.load.umax</tt></a></li>
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<li><a href="#int_atomic_load_umin"><tt>llvm.atomic.load.umin</tt></a></li>
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</ol>
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</li>
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<li><a href="#int_general">General intrinsics</a>
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<ol>
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<li><a href="#int_var_annotation">
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'<tt>llvm.var.annotation</tt>' Intrinsic</a></li>
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<li><a href="#int_annotation">
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'<tt>llvm.annotation.*</tt>' Intrinsic</a></li>
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<li><a href="#int_trap">
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'<tt>llvm.trap</tt>' Intrinsic</a></li>
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<li><a href="#int_stackprotector">
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'<tt>llvm.stackprotector</tt>' Intrinsic</a></li>
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</ol>
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</li>
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</ol>
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</li>
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</ol>
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<div class="doc_author">
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<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
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and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"> <a name="abstract">Abstract </a></div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This document is a reference manual for the LLVM assembly language.
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LLVM is a Static Single Assignment (SSA) based representation that provides
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type safety, low-level operations, flexibility, and the capability of
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representing 'all' high-level languages cleanly. It is the common code
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representation used throughout all phases of the LLVM compilation
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strategy.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section"> <a name="introduction">Introduction</a> </div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>The LLVM code representation is designed to be used in three
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different forms: as an in-memory compiler IR, as an on-disk bitcode
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representation (suitable for fast loading by a Just-In-Time compiler),
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and as a human readable assembly language representation. This allows
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LLVM to provide a powerful intermediate representation for efficient
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compiler transformations and analysis, while providing a natural means
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to debug and visualize the transformations. The three different forms
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of LLVM are all equivalent. This document describes the human readable
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representation and notation.</p>
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<p>The LLVM representation aims to be light-weight and low-level
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while being expressive, typed, and extensible at the same time. It
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aims to be a "universal IR" of sorts, by being at a low enough level
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that high-level ideas may be cleanly mapped to it (similar to how
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microprocessors are "universal IR's", allowing many source languages to
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be mapped to them). By providing type information, LLVM can be used as
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the target of optimizations: for example, through pointer analysis, it
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can be proven that a C automatic variable is never accessed outside of
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the current function... allowing it to be promoted to a simple SSA
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value instead of a memory location.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
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<div class="doc_text">
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<p>It is important to note that this document describes 'well formed'
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LLVM assembly language. There is a difference between what the parser
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accepts and what is considered 'well formed'. For example, the
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following instruction is syntactically okay, but not well formed:</p>
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|
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<div class="doc_code">
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|
<pre>
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%x = <a href="#i_add">add</a> i32 1, %x
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</pre>
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</div>
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<p>...because the definition of <tt>%x</tt> does not dominate all of
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its uses. The LLVM infrastructure provides a verification pass that may
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be used to verify that an LLVM module is well formed. This pass is
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automatically run by the parser after parsing input assembly and by
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the optimizer before it outputs bitcode. The violations pointed out
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by the verifier pass indicate bugs in transformation passes or input to
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the parser.</p>
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</div>
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<!-- Describe the typesetting conventions here. -->
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<!-- *********************************************************************** -->
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<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>LLVM identifiers come in two basic types: global and local. Global
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identifiers (functions, global variables) begin with the @ character. Local
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identifiers (register names, types) begin with the % character. Additionally,
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there are three different formats for identifiers, for different purposes:</p>
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|
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<ol>
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<li>Named values are represented as a string of characters with their prefix.
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For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
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|
regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
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|
Identifiers which require other characters in their names can be surrounded
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with quotes. Special characters may be escaped using "\xx" where xx is the
|
|
ASCII code for the character in hexadecimal. In this way, any character can
|
|
be used in a name value, even quotes themselves.
|
|
|
|
<li>Unnamed values are represented as an unsigned numeric value with their
|
|
prefix. For example, %12, @2, %44.</li>
|
|
|
|
<li>Constants, which are described in a <a href="#constants">section about
|
|
constants</a>, below.</li>
|
|
</ol>
|
|
|
|
<p>LLVM requires that values start with a prefix for two reasons: Compilers
|
|
don't need to worry about name clashes with reserved words, and the set of
|
|
reserved words may be expanded in the future without penalty. Additionally,
|
|
unnamed identifiers allow a compiler to quickly come up with a temporary
|
|
variable without having to avoid symbol table conflicts.</p>
|
|
|
|
<p>Reserved words in LLVM are very similar to reserved words in other
|
|
languages. There are keywords for different opcodes
|
|
('<tt><a href="#i_add">add</a></tt>',
|
|
'<tt><a href="#i_bitcast">bitcast</a></tt>',
|
|
'<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
|
|
href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
|
|
and others. These reserved words cannot conflict with variable names, because
|
|
none of them start with a prefix character ('%' or '@').</p>
|
|
|
|
<p>Here is an example of LLVM code to multiply the integer variable
|
|
'<tt>%X</tt>' by 8:</p>
|
|
|
|
<p>The easy way:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
%result = <a href="#i_mul">mul</a> i32 %X, 8
|
|
</pre>
|
|
</div>
|
|
|
|
<p>After strength reduction:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
%result = <a href="#i_shl">shl</a> i32 %X, i8 3
|
|
</pre>
|
|
</div>
|
|
|
|
<p>And the hard way:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
|
|
<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
|
|
%result = <a href="#i_add">add</a> i32 %1, %1
|
|
</pre>
|
|
</div>
|
|
|
|
<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
|
|
important lexical features of LLVM:</p>
|
|
|
|
<ol>
|
|
|
|
<li>Comments are delimited with a '<tt>;</tt>' and go until the end of
|
|
line.</li>
|
|
|
|
<li>Unnamed temporaries are created when the result of a computation is not
|
|
assigned to a named value.</li>
|
|
|
|
<li>Unnamed temporaries are numbered sequentially</li>
|
|
|
|
</ol>
|
|
|
|
<p>...and it also shows a convention that we follow in this document. When
|
|
demonstrating instructions, we will follow an instruction with a comment that
|
|
defines the type and name of value produced. Comments are shown in italic
|
|
text.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM programs are composed of "Module"s, each of which is a
|
|
translation unit of the input programs. Each module consists of
|
|
functions, global variables, and symbol table entries. Modules may be
|
|
combined together with the LLVM linker, which merges function (and
|
|
global variable) definitions, resolves forward declarations, and merges
|
|
symbol table entries. Here is an example of the "hello world" module:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre><i>; Declare the string constant as a global constant...</i>
|
|
<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
|
|
href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
|
|
|
|
<i>; External declaration of the puts function</i>
|
|
<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
|
|
|
|
<i>; Definition of main function</i>
|
|
define i32 @main() { <i>; i32()* </i>
|
|
<i>; Convert [13 x i8]* to i8 *...</i>
|
|
%cast210 = <a
|
|
href="#i_getelementptr">getelementptr</a> [13 x i8]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
|
|
|
|
<i>; Call puts function to write out the string to stdout...</i>
|
|
<a
|
|
href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
|
|
<a
|
|
href="#i_ret">ret</a> i32 0<br>}<br>
|
|
</pre>
|
|
</div>
|
|
|
|
<p>This example is made up of a <a href="#globalvars">global variable</a>
|
|
named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
|
|
function, and a <a href="#functionstructure">function definition</a>
|
|
for "<tt>main</tt>".</p>
|
|
|
|
<p>In general, a module is made up of a list of global values,
|
|
where both functions and global variables are global values. Global values are
|
|
represented by a pointer to a memory location (in this case, a pointer to an
|
|
array of char, and a pointer to a function), and have one of the following <a
|
|
href="#linkage">linkage types</a>.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="linkage">Linkage Types</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>
|
|
All Global Variables and Functions have one of the following types of linkage:
|
|
</p>
|
|
|
|
<dl>
|
|
|
|
<dt><tt><b><a name="linkage_private">private</a></b></tt>: </dt>
|
|
|
|
<dd>Global values with private linkage are only directly accessible by
|
|
objects in the current module. In particular, linking code into a module with
|
|
an private global value may cause the private to be renamed as necessary to
|
|
avoid collisions. Because the symbol is private to the module, all
|
|
references can be updated. This doesn't show up in any symbol table in the
|
|
object file.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_internal">internal</a></b></tt>: </dt>
|
|
|
|
<dd> Similar to private, but the value shows as a local symbol (STB_LOCAL in
|
|
the case of ELF) in the object file. This corresponds to the notion of the
|
|
'<tt>static</tt>' keyword in C.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
|
|
|
|
<dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
|
|
the same name when linkage occurs. This is typically used to implement
|
|
inline functions, templates, or other code which must be generated in each
|
|
translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
|
|
allowed to be discarded.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_common">common</a></b></tt>: </dt>
|
|
|
|
<dd>"<tt>common</tt>" linkage is exactly the same as <tt>linkonce</tt>
|
|
linkage, except that unreferenced <tt>common</tt> globals may not be
|
|
discarded. This is used for globals that may be emitted in multiple
|
|
translation units, but that are not guaranteed to be emitted into every
|
|
translation unit that uses them. One example of this is tentative
|
|
definitions in C, such as "<tt>int X;</tt>" at global scope.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
|
|
|
|
<dd>"<tt>weak</tt>" linkage is the same as <tt>common</tt> linkage, except
|
|
that some targets may choose to emit different assembly sequences for them
|
|
for target-dependent reasons. This is used for globals that are declared
|
|
"weak" in C source code.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
|
|
|
|
<dd>"<tt>appending</tt>" linkage may only be applied to global variables of
|
|
pointer to array type. When two global variables with appending linkage are
|
|
linked together, the two global arrays are appended together. This is the
|
|
LLVM, typesafe, equivalent of having the system linker append together
|
|
"sections" with identical names when .o files are linked.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
|
|
<dd>The semantics of this linkage follow the ELF object file model: the
|
|
symbol is weak until linked, if not linked, the symbol becomes null instead
|
|
of being an undefined reference.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
|
|
|
|
<dd>If none of the above identifiers are used, the global is externally
|
|
visible, meaning that it participates in linkage and can be used to resolve
|
|
external symbol references.
|
|
</dd>
|
|
</dl>
|
|
|
|
<p>
|
|
The next two types of linkage are targeted for Microsoft Windows platform
|
|
only. They are designed to support importing (exporting) symbols from (to)
|
|
DLLs (Dynamic Link Libraries).
|
|
</p>
|
|
|
|
<dl>
|
|
<dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
|
|
|
|
<dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
|
|
or variable via a global pointer to a pointer that is set up by the DLL
|
|
exporting the symbol. On Microsoft Windows targets, the pointer name is
|
|
formed by combining <code>__imp_</code> and the function or variable name.
|
|
</dd>
|
|
|
|
<dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
|
|
|
|
<dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
|
|
pointer to a pointer in a DLL, so that it can be referenced with the
|
|
<tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
|
|
name is formed by combining <code>__imp_</code> and the function or variable
|
|
name.
|
|
</dd>
|
|
|
|
</dl>
|
|
|
|
<p>For example, since the "<tt>.LC0</tt>"
|
|
variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
|
|
variable and was linked with this one, one of the two would be renamed,
|
|
preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
|
|
external (i.e., lacking any linkage declarations), they are accessible
|
|
outside of the current module.</p>
|
|
<p>It is illegal for a function <i>declaration</i>
|
|
to have any linkage type other than "externally visible", <tt>dllimport</tt>,
|
|
or <tt>extern_weak</tt>.</p>
|
|
<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
|
|
linkages.</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="callingconv">Calling Conventions</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
|
|
and <a href="#i_invoke">invokes</a> can all have an optional calling convention
|
|
specified for the call. The calling convention of any pair of dynamic
|
|
caller/callee must match, or the behavior of the program is undefined. The
|
|
following calling conventions are supported by LLVM, and more may be added in
|
|
the future:</p>
|
|
|
|
<dl>
|
|
<dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
|
|
|
|
<dd>This calling convention (the default if no other calling convention is
|
|
specified) matches the target C calling conventions. This calling convention
|
|
supports varargs function calls and tolerates some mismatch in the declared
|
|
prototype and implemented declaration of the function (as does normal C).
|
|
</dd>
|
|
|
|
<dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
|
|
|
|
<dd>This calling convention attempts to make calls as fast as possible
|
|
(e.g. by passing things in registers). This calling convention allows the
|
|
target to use whatever tricks it wants to produce fast code for the target,
|
|
without having to conform to an externally specified ABI (Application Binary
|
|
Interface). Implementations of this convention should allow arbitrary
|
|
<a href="CodeGenerator.html#tailcallopt">tail call optimization</a> to be
|
|
supported. This calling convention does not support varargs and requires the
|
|
prototype of all callees to exactly match the prototype of the function
|
|
definition.
|
|
</dd>
|
|
|
|
<dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
|
|
|
|
<dd>This calling convention attempts to make code in the caller as efficient
|
|
as possible under the assumption that the call is not commonly executed. As
|
|
such, these calls often preserve all registers so that the call does not break
|
|
any live ranges in the caller side. This calling convention does not support
|
|
varargs and requires the prototype of all callees to exactly match the
|
|
prototype of the function definition.
|
|
</dd>
|
|
|
|
<dt><b>"<tt>cc <<em>n</em>></tt>" - Numbered convention</b>:</dt>
|
|
|
|
<dd>Any calling convention may be specified by number, allowing
|
|
target-specific calling conventions to be used. Target specific calling
|
|
conventions start at 64.
|
|
</dd>
|
|
</dl>
|
|
|
|
<p>More calling conventions can be added/defined on an as-needed basis, to
|
|
support pascal conventions or any other well-known target-independent
|
|
convention.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="visibility">Visibility Styles</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>
|
|
All Global Variables and Functions have one of the following visibility styles:
|
|
</p>
|
|
|
|
<dl>
|
|
<dt><b>"<tt>default</tt>" - Default style</b>:</dt>
|
|
|
|
<dd>On targets that use the ELF object file format, default visibility means
|
|
that the declaration is visible to other
|
|
modules and, in shared libraries, means that the declared entity may be
|
|
overridden. On Darwin, default visibility means that the declaration is
|
|
visible to other modules. Default visibility corresponds to "external
|
|
linkage" in the language.
|
|
</dd>
|
|
|
|
<dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
|
|
|
|
<dd>Two declarations of an object with hidden visibility refer to the same
|
|
object if they are in the same shared object. Usually, hidden visibility
|
|
indicates that the symbol will not be placed into the dynamic symbol table,
|
|
so no other module (executable or shared library) can reference it
|
|
directly.
|
|
</dd>
|
|
|
|
<dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
|
|
|
|
<dd>On ELF, protected visibility indicates that the symbol will be placed in
|
|
the dynamic symbol table, but that references within the defining module will
|
|
bind to the local symbol. That is, the symbol cannot be overridden by another
|
|
module.
|
|
</dd>
|
|
</dl>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="namedtypes">Named Types</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM IR allows you to specify name aliases for certain types. This can make
|
|
it easier to read the IR and make the IR more condensed (particularly when
|
|
recursive types are involved). An example of a name specification is:
|
|
</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
%mytype = type { %mytype*, i32 }
|
|
</pre>
|
|
</div>
|
|
|
|
<p>You may give a name to any <a href="#typesystem">type</a> except "<a
|
|
href="t_void">void</a>". Type name aliases may be used anywhere a type is
|
|
expected with the syntax "%mytype".</p>
|
|
|
|
<p>Note that type names are aliases for the structural type that they indicate,
|
|
and that you can therefore specify multiple names for the same type. This often
|
|
leads to confusing behavior when dumping out a .ll file. Since LLVM IR uses
|
|
structural typing, the name is not part of the type. When printing out LLVM IR,
|
|
the printer will pick <em>one name</em> to render all types of a particular
|
|
shape. This means that if you have code where two different source types end up
|
|
having the same LLVM type, that the dumper will sometimes print the "wrong" or
|
|
unexpected type. This is an important design point and isn't going to
|
|
change.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="globalvars">Global Variables</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Global variables define regions of memory allocated at compilation time
|
|
instead of run-time. Global variables may optionally be initialized, may have
|
|
an explicit section to be placed in, and may have an optional explicit alignment
|
|
specified. A variable may be defined as "thread_local", which means that it
|
|
will not be shared by threads (each thread will have a separated copy of the
|
|
variable). A variable may be defined as a global "constant," which indicates
|
|
that the contents of the variable will <b>never</b> be modified (enabling better
|
|
optimization, allowing the global data to be placed in the read-only section of
|
|
an executable, etc). Note that variables that need runtime initialization
|
|
cannot be marked "constant" as there is a store to the variable.</p>
|
|
|
|
<p>
|
|
LLVM explicitly allows <em>declarations</em> of global variables to be marked
|
|
constant, even if the final definition of the global is not. This capability
|
|
can be used to enable slightly better optimization of the program, but requires
|
|
the language definition to guarantee that optimizations based on the
|
|
'constantness' are valid for the translation units that do not include the
|
|
definition.
|
|
</p>
|
|
|
|
<p>As SSA values, global variables define pointer values that are in
|
|
scope (i.e. they dominate) all basic blocks in the program. Global
|
|
variables always define a pointer to their "content" type because they
|
|
describe a region of memory, and all memory objects in LLVM are
|
|
accessed through pointers.</p>
|
|
|
|
<p>A global variable may be declared to reside in a target-specifc numbered
|
|
address space. For targets that support them, address spaces may affect how
|
|
optimizations are performed and/or what target instructions are used to access
|
|
the variable. The default address space is zero. The address space qualifier
|
|
must precede any other attributes.</p>
|
|
|
|
<p>LLVM allows an explicit section to be specified for globals. If the target
|
|
supports it, it will emit globals to the section specified.</p>
|
|
|
|
<p>An explicit alignment may be specified for a global. If not present, or if
|
|
the alignment is set to zero, the alignment of the global is set by the target
|
|
to whatever it feels convenient. If an explicit alignment is specified, the
|
|
global is forced to have at least that much alignment. All alignments must be
|
|
a power of 2.</p>
|
|
|
|
<p>For example, the following defines a global in a numbered address space with
|
|
an initializer, section, and alignment:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
@G = addrspace(5) constant float 1.0, section "foo", align 4
|
|
</pre>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="functionstructure">Functions</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
|
|
an optional <a href="#linkage">linkage type</a>, an optional
|
|
<a href="#visibility">visibility style</a>, an optional
|
|
<a href="#callingconv">calling convention</a>, a return type, an optional
|
|
<a href="#paramattrs">parameter attribute</a> for the return type, a function
|
|
name, a (possibly empty) argument list (each with optional
|
|
<a href="#paramattrs">parameter attributes</a>), optional
|
|
<a href="#fnattrs">function attributes</a>, an optional section,
|
|
an optional alignment, an optional <a href="#gc">garbage collector name</a>,
|
|
an opening curly brace, a list of basic blocks, and a closing curly brace.
|
|
|
|
LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
|
|
optional <a href="#linkage">linkage type</a>, an optional
|
|
<a href="#visibility">visibility style</a>, an optional
|
|
<a href="#callingconv">calling convention</a>, a return type, an optional
|
|
<a href="#paramattrs">parameter attribute</a> for the return type, a function
|
|
name, a possibly empty list of arguments, an optional alignment, and an optional
|
|
<a href="#gc">garbage collector name</a>.</p>
|
|
|
|
<p>A function definition contains a list of basic blocks, forming the CFG
|
|
(Control Flow Graph) for
|
|
the function. Each basic block may optionally start with a label (giving the
|
|
basic block a symbol table entry), contains a list of instructions, and ends
|
|
with a <a href="#terminators">terminator</a> instruction (such as a branch or
|
|
function return).</p>
|
|
|
|
<p>The first basic block in a function is special in two ways: it is immediately
|
|
executed on entrance to the function, and it is not allowed to have predecessor
|
|
basic blocks (i.e. there can not be any branches to the entry block of a
|
|
function). Because the block can have no predecessors, it also cannot have any
|
|
<a href="#i_phi">PHI nodes</a>.</p>
|
|
|
|
<p>LLVM allows an explicit section to be specified for functions. If the target
|
|
supports it, it will emit functions to the section specified.</p>
|
|
|
|
<p>An explicit alignment may be specified for a function. If not present, or if
|
|
the alignment is set to zero, the alignment of the function is set by the target
|
|
to whatever it feels convenient. If an explicit alignment is specified, the
|
|
function is forced to have at least that much alignment. All alignments must be
|
|
a power of 2.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<div class="doc_code">
|
|
<tt>
|
|
define [<a href="#linkage">linkage</a>] [<a href="#visibility">visibility</a>]
|
|
[<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>]
|
|
<ResultType> @<FunctionName> ([argument list])
|
|
[<a href="#fnattrs">fn Attrs</a>] [section "name"] [align N]
|
|
[<a href="#gc">gc</a>] { ... }
|
|
</tt>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="aliasstructure">Aliases</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<p>Aliases act as "second name" for the aliasee value (which can be either
|
|
function, global variable, another alias or bitcast of global value). Aliases
|
|
may have an optional <a href="#linkage">linkage type</a>, and an
|
|
optional <a href="#visibility">visibility style</a>.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
@<Name> = alias [Linkage] [Visibility] <AliaseeTy> @<Aliasee>
|
|
</pre>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
|
|
<div class="doc_text">
|
|
<p>The return type and each parameter of a function type may have a set of
|
|
<i>parameter attributes</i> associated with them. Parameter attributes are
|
|
used to communicate additional information about the result or parameters of
|
|
a function. Parameter attributes are considered to be part of the function,
|
|
not of the function type, so functions with different parameter attributes
|
|
can have the same function type.</p>
|
|
|
|
<p>Parameter attributes are simple keywords that follow the type specified. If
|
|
multiple parameter attributes are needed, they are space separated. For
|
|
example:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
declare i32 @printf(i8* noalias , ...)
|
|
declare i32 @atoi(i8 zeroext)
|
|
declare signext i8 @returns_signed_char()
|
|
</pre>
|
|
</div>
|
|
|
|
<p>Note that any attributes for the function result (<tt>nounwind</tt>,
|
|
<tt>readonly</tt>) come immediately after the argument list.</p>
|
|
|
|
<p>Currently, only the following parameter attributes are defined:</p>
|
|
<dl>
|
|
<dt><tt>zeroext</tt></dt>
|
|
<dd>This indicates to the code generator that the parameter or return value
|
|
should be zero-extended to a 32-bit value by the caller (for a parameter)
|
|
or the callee (for a return value).</dd>
|
|
|
|
<dt><tt>signext</tt></dt>
|
|
<dd>This indicates to the code generator that the parameter or return value
|
|
should be sign-extended to a 32-bit value by the caller (for a parameter)
|
|
or the callee (for a return value).</dd>
|
|
|
|
<dt><tt>inreg</tt></dt>
|
|
<dd>This indicates that this parameter or return value should be treated
|
|
in a special target-dependent fashion during while emitting code for a
|
|
function call or return (usually, by putting it in a register as opposed
|
|
to memory, though some targets use it to distinguish between two different
|
|
kinds of registers). Use of this attribute is target-specific.</dd>
|
|
|
|
<dt><tt><a name="byval">byval</a></tt></dt>
|
|
<dd>This indicates that the pointer parameter should really be passed by
|
|
value to the function. The attribute implies that a hidden copy of the
|
|
pointee is made between the caller and the callee, so the callee is unable
|
|
to modify the value in the callee. This attribute is only valid on LLVM
|
|
pointer arguments. It is generally used to pass structs and arrays by
|
|
value, but is also valid on pointers to scalars. The copy is considered to
|
|
belong to the caller not the callee (for example,
|
|
<tt><a href="#readonly">readonly</a></tt> functions should not write to
|
|
<tt>byval</tt> parameters). This is not a valid attribute for return
|
|
values. The byval attribute also supports specifying an alignment with the
|
|
align attribute. This has a target-specific effect on the code generator
|
|
that usually indicates a desired alignment for the synthesized stack
|
|
slot.</dd>
|
|
|
|
<dt><tt>sret</tt></dt>
|
|
<dd>This indicates that the pointer parameter specifies the address of a
|
|
structure that is the return value of the function in the source program.
|
|
This pointer must be guaranteed by the caller to be valid: loads and stores
|
|
to the structure may be assumed by the callee to not to trap. This may only
|
|
be applied to the first parameter. This is not a valid attribute for
|
|
return values. </dd>
|
|
|
|
<dt><tt>noalias</tt></dt>
|
|
<dd>This indicates that the pointer does not alias any global or any other
|
|
parameter. The caller is responsible for ensuring that this is the
|
|
case. On a function return value, <tt>noalias</tt> additionally indicates
|
|
that the pointer does not alias any other pointers visible to the
|
|
caller. For further details, please see the discussion of the NoAlias
|
|
response in
|
|
<a href="http://llvm.org/docs/AliasAnalysis.html#MustMayNo">alias
|
|
analysis</a>.</dd>
|
|
|
|
<dt><tt>nocapture</tt></dt>
|
|
<dd>This indicates that the callee does not make any copies of the pointer
|
|
that outlive the callee itself. This is not a valid attribute for return
|
|
values.</dd>
|
|
|
|
<dt><tt>nest</tt></dt>
|
|
<dd>This indicates that the pointer parameter can be excised using the
|
|
<a href="#int_trampoline">trampoline intrinsics</a>. This is not a valid
|
|
attribute for return values.</dd>
|
|
</dl>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="gc">Garbage Collector Names</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>Each function may specify a garbage collector name, which is simply a
|
|
string.</p>
|
|
|
|
<div class="doc_code"><pre
|
|
>define void @f() gc "name" { ...</pre></div>
|
|
|
|
<p>The compiler declares the supported values of <i>name</i>. Specifying a
|
|
collector which will cause the compiler to alter its output in order to support
|
|
the named garbage collection algorithm.</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="fnattrs">Function Attributes</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Function attributes are set to communicate additional information about
|
|
a function. Function attributes are considered to be part of the function,
|
|
not of the function type, so functions with different parameter attributes
|
|
can have the same function type.</p>
|
|
|
|
<p>Function attributes are simple keywords that follow the type specified. If
|
|
multiple attributes are needed, they are space separated. For
|
|
example:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
define void @f() noinline { ... }
|
|
define void @f() alwaysinline { ... }
|
|
define void @f() alwaysinline optsize { ... }
|
|
define void @f() optsize
|
|
</pre>
|
|
</div>
|
|
|
|
<dl>
|
|
<dt><tt>alwaysinline</tt></dt>
|
|
<dd>This attribute indicates that the inliner should attempt to inline this
|
|
function into callers whenever possible, ignoring any active inlining size
|
|
threshold for this caller.</dd>
|
|
|
|
<dt><tt>noinline</tt></dt>
|
|
<dd>This attribute indicates that the inliner should never inline this function
|
|
in any situation. This attribute may not be used together with the
|
|
<tt>alwaysinline</tt> attribute.</dd>
|
|
|
|
<dt><tt>optsize</tt></dt>
|
|
<dd>This attribute suggests that optimization passes and code generator passes
|
|
make choices that keep the code size of this function low, and otherwise do
|
|
optimizations specifically to reduce code size.</dd>
|
|
|
|
<dt><tt>noreturn</tt></dt>
|
|
<dd>This function attribute indicates that the function never returns normally.
|
|
This produces undefined behavior at runtime if the function ever does
|
|
dynamically return.</dd>
|
|
|
|
<dt><tt>nounwind</tt></dt>
|
|
<dd>This function attribute indicates that the function never returns with an
|
|
unwind or exceptional control flow. If the function does unwind, its runtime
|
|
behavior is undefined.</dd>
|
|
|
|
<dt><tt>readnone</tt></dt>
|
|
<dd>This attribute indicates that the function computes its result (or the
|
|
exception it throws) based strictly on its arguments, without dereferencing any
|
|
pointer arguments or otherwise accessing any mutable state (e.g. memory, control
|
|
registers, etc) visible to caller functions. It does not write through any
|
|
pointer arguments (including <tt><a href="#byval">byval</a></tt> arguments) and
|
|
never changes any state visible to callers.</dd>
|
|
|
|
<dt><tt><a name="readonly">readonly</a></tt></dt>
|
|
<dd>This attribute indicates that the function does not write through any
|
|
pointer arguments (including <tt><a href="#byval">byval</a></tt> arguments)
|
|
or otherwise modify any state (e.g. memory, control registers, etc) visible to
|
|
caller functions. It may dereference pointer arguments and read state that may
|
|
be set in the caller. A readonly function always returns the same value (or
|
|
throws the same exception) when called with the same set of arguments and global
|
|
state.</dd>
|
|
|
|
<dt><tt><a name="ssp">ssp</a></tt></dt>
|
|
<dd>This attribute indicates that the function should emit a stack smashing
|
|
protector. It is in the form of a "canary"—a random value placed on the
|
|
stack before the local variables that's checked upon return from the function to
|
|
see if it has been overwritten. A heuristic is used to determine if a function
|
|
needs stack protectors or not.
|
|
|
|
<p>If a function that has an <tt>ssp</tt> attribute is inlined into a function
|
|
that doesn't have an <tt>ssp</tt> attribute, then the resulting function will
|
|
have an <tt>ssp</tt> attribute.</p></dd>
|
|
|
|
<dt><tt>sspreq</tt></dt>
|
|
<dd>This attribute indicates that the function should <em>always</em> emit a
|
|
stack smashing protector. This overrides the <tt><a href="#ssp">ssp</a></tt>
|
|
function attribute.
|
|
|
|
<p>If a function that has an <tt>sspreq</tt> attribute is inlined into a
|
|
function that doesn't have an <tt>sspreq</tt> attribute or which has
|
|
an <tt>ssp</tt> attribute, then the resulting function will have
|
|
an <tt>sspreq</tt> attribute.</p></dd>
|
|
</dl>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="moduleasm">Module-Level Inline Assembly</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
Modules may contain "module-level inline asm" blocks, which corresponds to the
|
|
GCC "file scope inline asm" blocks. These blocks are internally concatenated by
|
|
LLVM and treated as a single unit, but may be separated in the .ll file if
|
|
desired. The syntax is very simple:
|
|
</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
module asm "inline asm code goes here"
|
|
module asm "more can go here"
|
|
</pre>
|
|
</div>
|
|
|
|
<p>The strings can contain any character by escaping non-printable characters.
|
|
The escape sequence used is simply "\xx" where "xx" is the two digit hex code
|
|
for the number.
|
|
</p>
|
|
|
|
<p>
|
|
The inline asm code is simply printed to the machine code .s file when
|
|
assembly code is generated.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="datalayout">Data Layout</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>A module may specify a target specific data layout string that specifies how
|
|
data is to be laid out in memory. The syntax for the data layout is simply:</p>
|
|
<pre> target datalayout = "<i>layout specification</i>"</pre>
|
|
<p>The <i>layout specification</i> consists of a list of specifications
|
|
separated by the minus sign character ('-'). Each specification starts with a
|
|
letter and may include other information after the letter to define some
|
|
aspect of the data layout. The specifications accepted are as follows: </p>
|
|
<dl>
|
|
<dt><tt>E</tt></dt>
|
|
<dd>Specifies that the target lays out data in big-endian form. That is, the
|
|
bits with the most significance have the lowest address location.</dd>
|
|
<dt><tt>e</tt></dt>
|
|
<dd>Specifies that the target lays out data in little-endian form. That is,
|
|
the bits with the least significance have the lowest address location.</dd>
|
|
<dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
|
|
<dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
|
|
<i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
|
|
alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
|
|
too.</dd>
|
|
<dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
|
|
<dd>This specifies the alignment for an integer type of a given bit
|
|
<i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
|
|
<dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
|
|
<dd>This specifies the alignment for a vector type of a given bit
|
|
<i>size</i>.</dd>
|
|
<dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
|
|
<dd>This specifies the alignment for a floating point type of a given bit
|
|
<i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
|
|
(double).</dd>
|
|
<dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
|
|
<dd>This specifies the alignment for an aggregate type of a given bit
|
|
<i>size</i>.</dd>
|
|
</dl>
|
|
<p>When constructing the data layout for a given target, LLVM starts with a
|
|
default set of specifications which are then (possibly) overriden by the
|
|
specifications in the <tt>datalayout</tt> keyword. The default specifications
|
|
are given in this list:</p>
|
|
<ul>
|
|
<li><tt>E</tt> - big endian</li>
|
|
<li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
|
|
<li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
|
|
<li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
|
|
<li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
|
|
<li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
|
|
<li><tt>i64:32:64</tt> - i64 has ABI alignment of 32-bits but preferred
|
|
alignment of 64-bits</li>
|
|
<li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
|
|
<li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
|
|
<li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
|
|
<li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
|
|
<li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
|
|
</ul>
|
|
<p>When LLVM is determining the alignment for a given type, it uses the
|
|
following rules:</p>
|
|
<ol>
|
|
<li>If the type sought is an exact match for one of the specifications, that
|
|
specification is used.</li>
|
|
<li>If no match is found, and the type sought is an integer type, then the
|
|
smallest integer type that is larger than the bitwidth of the sought type is
|
|
used. If none of the specifications are larger than the bitwidth then the the
|
|
largest integer type is used. For example, given the default specifications
|
|
above, the i7 type will use the alignment of i8 (next largest) while both
|
|
i65 and i256 will use the alignment of i64 (largest specified).</li>
|
|
<li>If no match is found, and the type sought is a vector type, then the
|
|
largest vector type that is smaller than the sought vector type will be used
|
|
as a fall back. This happens because <128 x double> can be implemented
|
|
in terms of 64 <2 x double>, for example.</li>
|
|
</ol>
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="typesystem">Type System</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The LLVM type system is one of the most important features of the
|
|
intermediate representation. Being typed enables a number of
|
|
optimizations to be performed on the intermediate representation directly,
|
|
without having to do
|
|
extra analyses on the side before the transformation. A strong type
|
|
system makes it easier to read the generated code and enables novel
|
|
analyses and transformations that are not feasible to perform on normal
|
|
three address code representations.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="t_classifications">Type
|
|
Classifications</a> </div>
|
|
<div class="doc_text">
|
|
<p>The types fall into a few useful
|
|
classifications:</p>
|
|
|
|
<table border="1" cellspacing="0" cellpadding="4">
|
|
<tbody>
|
|
<tr><th>Classification</th><th>Types</th></tr>
|
|
<tr>
|
|
<td><a href="#t_integer">integer</a></td>
|
|
<td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><a href="#t_floating">floating point</a></td>
|
|
<td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
|
|
</tr>
|
|
<tr>
|
|
<td><a name="t_firstclass">first class</a></td>
|
|
<td><a href="#t_integer">integer</a>,
|
|
<a href="#t_floating">floating point</a>,
|
|
<a href="#t_pointer">pointer</a>,
|
|
<a href="#t_vector">vector</a>,
|
|
<a href="#t_struct">structure</a>,
|
|
<a href="#t_array">array</a>,
|
|
<a href="#t_label">label</a>.
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><a href="#t_primitive">primitive</a></td>
|
|
<td><a href="#t_label">label</a>,
|
|
<a href="#t_void">void</a>,
|
|
<a href="#t_floating">floating point</a>.</td>
|
|
</tr>
|
|
<tr>
|
|
<td><a href="#t_derived">derived</a></td>
|
|
<td><a href="#t_integer">integer</a>,
|
|
<a href="#t_array">array</a>,
|
|
<a href="#t_function">function</a>,
|
|
<a href="#t_pointer">pointer</a>,
|
|
<a href="#t_struct">structure</a>,
|
|
<a href="#t_pstruct">packed structure</a>,
|
|
<a href="#t_vector">vector</a>,
|
|
<a href="#t_opaque">opaque</a>.
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>The <a href="#t_firstclass">first class</a> types are perhaps the
|
|
most important. Values of these types are the only ones which can be
|
|
produced by instructions, passed as arguments, or used as operands to
|
|
instructions.</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
|
|
|
|
<div class="doc_text">
|
|
<p>The primitive types are the fundamental building blocks of the LLVM
|
|
system.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
|
|
|
|
<div class="doc_text">
|
|
<table>
|
|
<tbody>
|
|
<tr><th>Type</th><th>Description</th></tr>
|
|
<tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
|
|
<tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
|
|
<tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
|
|
<tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
|
|
<tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>The void type does not represent any value and has no size.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
void
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>The label type represents code labels.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
label
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The real power in LLVM comes from the derived types in the system.
|
|
This is what allows a programmer to represent arrays, functions,
|
|
pointers, and other useful types. Note that these derived types may be
|
|
recursive: For example, it is possible to have a two dimensional array.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The integer type is a very simple derived type that simply specifies an
|
|
arbitrary bit width for the integer type desired. Any bit width from 1 bit to
|
|
2^23-1 (about 8 million) can be specified.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
iN
|
|
</pre>
|
|
|
|
<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
|
|
value.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tbody>
|
|
<tr>
|
|
<td><tt>i1</tt></td>
|
|
<td>a single-bit integer.</td>
|
|
</tr><tr>
|
|
<td><tt>i32</tt></td>
|
|
<td>a 32-bit integer.</td>
|
|
</tr><tr>
|
|
<td><tt>i1942652</tt></td>
|
|
<td>a really big integer of over 1 million bits.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>Note that the code generator does not yet support large integer types
|
|
to be used as function return types. The specific limit on how large a
|
|
return type the code generator can currently handle is target-dependent;
|
|
currently it's often 64 bits for 32-bit targets and 128 bits for 64-bit
|
|
targets.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The array type is a very simple derived type that arranges elements
|
|
sequentially in memory. The array type requires a size (number of
|
|
elements) and an underlying data type.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
[<# elements> x <elementtype>]
|
|
</pre>
|
|
|
|
<p>The number of elements is a constant integer value; elementtype may
|
|
be any type with a size.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>[40 x i32]</tt></td>
|
|
<td class="left">Array of 40 32-bit integer values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>[41 x i32]</tt></td>
|
|
<td class="left">Array of 41 32-bit integer values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>[4 x i8]</tt></td>
|
|
<td class="left">Array of 4 8-bit integer values.</td>
|
|
</tr>
|
|
</table>
|
|
<p>Here are some examples of multidimensional arrays:</p>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>[3 x [4 x i32]]</tt></td>
|
|
<td class="left">3x4 array of 32-bit integer values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>[12 x [10 x float]]</tt></td>
|
|
<td class="left">12x10 array of single precision floating point values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
|
|
<td class="left">2x3x4 array of 16-bit integer values.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
|
|
length array. Normally, accesses past the end of an array are undefined in
|
|
LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
|
|
As a special case, however, zero length arrays are recognized to be variable
|
|
length. This allows implementation of 'pascal style arrays' with the LLVM
|
|
type "{ i32, [0 x float]}", for example.</p>
|
|
|
|
<p>Note that the code generator does not yet support large aggregate types
|
|
to be used as function return types. The specific limit on how large an
|
|
aggregate return type the code generator can currently handle is
|
|
target-dependent, and also dependent on the aggregate element types.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The function type can be thought of as a function signature. It
|
|
consists of a return type and a list of formal parameter types. The
|
|
return type of a function type is a scalar type, a void type, or a struct type.
|
|
If the return type is a struct type then all struct elements must be of first
|
|
class types, and the struct must have at least one element.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<returntype list> (<parameter list>)
|
|
</pre>
|
|
|
|
<p>...where '<tt><parameter list></tt>' is a comma-separated list of type
|
|
specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
|
|
which indicates that the function takes a variable number of arguments.
|
|
Variable argument functions can access their arguments with the <a
|
|
href="#int_varargs">variable argument handling intrinsic</a> functions.
|
|
'<tt><returntype list></tt>' is a comma-separated list of
|
|
<a href="#t_firstclass">first class</a> type specifiers.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>i32 (i32)</tt></td>
|
|
<td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
|
|
</td>
|
|
</tr><tr class="layout">
|
|
<td class="left"><tt>float (i16 signext, i32 *) *
|
|
</tt></td>
|
|
<td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
|
|
an <tt>i16</tt> that should be sign extended and a
|
|
<a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
|
|
<tt>float</tt>.
|
|
</td>
|
|
</tr><tr class="layout">
|
|
<td class="left"><tt>i32 (i8*, ...)</tt></td>
|
|
<td class="left">A vararg function that takes at least one
|
|
<a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
|
|
which returns an integer. This is the signature for <tt>printf</tt> in
|
|
LLVM.
|
|
</td>
|
|
</tr><tr class="layout">
|
|
<td class="left"><tt>{i32, i32} (i32)</tt></td>
|
|
<td class="left">A function taking an <tt>i32</tt>, returning two
|
|
<tt>i32</tt> values as an aggregate of type <tt>{ i32, i32 }</tt>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>The structure type is used to represent a collection of data members
|
|
together in memory. The packing of the field types is defined to match
|
|
the ABI of the underlying processor. The elements of a structure may
|
|
be any type that has a size.</p>
|
|
<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
|
|
and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
|
|
field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
|
|
instruction.</p>
|
|
<h5>Syntax:</h5>
|
|
<pre> { <type list> }<br></pre>
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>{ i32, i32, i32 }</tt></td>
|
|
<td class="left">A triple of three <tt>i32</tt> values</td>
|
|
</tr><tr class="layout">
|
|
<td class="left"><tt>{ float, i32 (i32) * }</tt></td>
|
|
<td class="left">A pair, where the first element is a <tt>float</tt> and the
|
|
second element is a <a href="#t_pointer">pointer</a> to a
|
|
<a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
|
|
an <tt>i32</tt>.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
<p>Note that the code generator does not yet support large aggregate types
|
|
to be used as function return types. The specific limit on how large an
|
|
aggregate return type the code generator can currently handle is
|
|
target-dependent, and also dependent on the aggregate element types.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>The packed structure type is used to represent a collection of data members
|
|
together in memory. There is no padding between fields. Further, the alignment
|
|
of a packed structure is 1 byte. The elements of a packed structure may
|
|
be any type that has a size.</p>
|
|
<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
|
|
and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
|
|
field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
|
|
instruction.</p>
|
|
<h5>Syntax:</h5>
|
|
<pre> < { <type list> } > <br></pre>
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>< { i32, i32, i32 } ></tt></td>
|
|
<td class="left">A triple of three <tt>i32</tt> values</td>
|
|
</tr><tr class="layout">
|
|
<td class="left">
|
|
<tt>< { float, i32 (i32)* } ></tt></td>
|
|
<td class="left">A pair, where the first element is a <tt>float</tt> and the
|
|
second element is a <a href="#t_pointer">pointer</a> to a
|
|
<a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
|
|
an <tt>i32</tt>.</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>As in many languages, the pointer type represents a pointer or
|
|
reference to another object, which must live in memory. Pointer types may have
|
|
an optional address space attribute defining the target-specific numbered
|
|
address space where the pointed-to object resides. The default address space is
|
|
zero.</p>
|
|
|
|
<p>Note that LLVM does not permit pointers to void (<tt>void*</tt>) nor does
|
|
it permit pointers to labels (<tt>label*</tt>). Use <tt>i8*</tt> intead.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre> <type> *<br></pre>
|
|
<h5>Examples:</h5>
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>[4 x i32]*</tt></td>
|
|
<td class="left">A <a href="#t_pointer">pointer</a> to <a
|
|
href="#t_array">array</a> of four <tt>i32</tt> values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>i32 (i32 *) *</tt></td>
|
|
<td class="left"> A <a href="#t_pointer">pointer</a> to a <a
|
|
href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
|
|
<tt>i32</tt>.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>i32 addrspace(5)*</tt></td>
|
|
<td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
|
|
that resides in address space #5.</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>A vector type is a simple derived type that represents a vector
|
|
of elements. Vector types are used when multiple primitive data
|
|
are operated in parallel using a single instruction (SIMD).
|
|
A vector type requires a size (number of
|
|
elements) and an underlying primitive data type. Vectors must have a power
|
|
of two length (1, 2, 4, 8, 16 ...). Vector types are
|
|
considered <a href="#t_firstclass">first class</a>.</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
< <# elements> x <elementtype> >
|
|
</pre>
|
|
|
|
<p>The number of elements is a constant integer value; elementtype may
|
|
be any integer or floating point type.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt><4 x i32></tt></td>
|
|
<td class="left">Vector of 4 32-bit integer values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt><8 x float></tt></td>
|
|
<td class="left">Vector of 8 32-bit floating-point values.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt><2 x i64></tt></td>
|
|
<td class="left">Vector of 2 64-bit integer values.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
<p>Note that the code generator does not yet support large vector types
|
|
to be used as function return types. The specific limit on how large a
|
|
vector return type codegen can currently handle is target-dependent;
|
|
currently it's often a few times longer than a hardware vector register.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>Opaque types are used to represent unknown types in the system. This
|
|
corresponds (for example) to the C notion of a forward declared structure type.
|
|
In LLVM, opaque types can eventually be resolved to any type (not just a
|
|
structure type).</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
opaque
|
|
</pre>
|
|
|
|
<h5>Examples:</h5>
|
|
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>opaque</tt></td>
|
|
<td class="left">An opaque type.</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="t_uprefs">Type Up-references</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
An "up reference" allows you to refer to a lexically enclosing type without
|
|
requiring it to have a name. For instance, a structure declaration may contain a
|
|
pointer to any of the types it is lexically a member of. Example of up
|
|
references (with their equivalent as named type declarations) include:</p>
|
|
|
|
<pre>
|
|
{ \2 * } %x = type { %t* }
|
|
{ \2 }* %y = type { %y }*
|
|
\1* %z = type %z*
|
|
</pre>
|
|
|
|
<p>
|
|
An up reference is needed by the asmprinter for printing out cyclic types when
|
|
there is no declared name for a type in the cycle. Because the asmprinter does
|
|
not want to print out an infinite type string, it needs a syntax to handle
|
|
recursive types that have no names (all names are optional in llvm IR).
|
|
</p>
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
\<level>
|
|
</pre>
|
|
|
|
<p>
|
|
The level is the count of the lexical type that is being referred to.
|
|
</p>
|
|
|
|
<h5>Examples:</h5>
|
|
|
|
<table class="layout">
|
|
<tr class="layout">
|
|
<td class="left"><tt>\1*</tt></td>
|
|
<td class="left">Self-referential pointer.</td>
|
|
</tr>
|
|
<tr class="layout">
|
|
<td class="left"><tt>{ { \3*, i8 }, i32 }</tt></td>
|
|
<td class="left">Recursive structure where the upref refers to the out-most
|
|
structure.</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="constants">Constants</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM has several different basic types of constants. This section describes
|
|
them all and their syntax.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<dl>
|
|
<dt><b>Boolean constants</b></dt>
|
|
|
|
<dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
|
|
constants of the <tt><a href="#t_primitive">i1</a></tt> type.
|
|
</dd>
|
|
|
|
<dt><b>Integer constants</b></dt>
|
|
|
|
<dd>Standard integers (such as '4') are constants of the <a
|
|
href="#t_integer">integer</a> type. Negative numbers may be used with
|
|
integer types.
|
|
</dd>
|
|
|
|
<dt><b>Floating point constants</b></dt>
|
|
|
|
<dd>Floating point constants use standard decimal notation (e.g. 123.421),
|
|
exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
|
|
notation (see below). The assembler requires the exact decimal value of
|
|
a floating-point constant. For example, the assembler accepts 1.25 but
|
|
rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
|
|
constants must have a <a href="#t_floating">floating point</a> type. </dd>
|
|
|
|
<dt><b>Null pointer constants</b></dt>
|
|
|
|
<dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
|
|
and must be of <a href="#t_pointer">pointer type</a>.</dd>
|
|
|
|
</dl>
|
|
|
|
<p>The one non-intuitive notation for constants is the optional hexadecimal form
|
|
of floating point constants. For example, the form '<tt>double
|
|
0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
|
|
4.5e+15</tt>'. The only time hexadecimal floating point constants are required
|
|
(and the only time that they are generated by the disassembler) is when a
|
|
floating point constant must be emitted but it cannot be represented as a
|
|
decimal floating point number. For example, NaN's, infinities, and other
|
|
special values are represented in their IEEE hexadecimal format so that
|
|
assembly and disassembly do not cause any bits to change in the constants.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>Aggregate constants arise from aggregation of simple constants
|
|
and smaller aggregate constants.</p>
|
|
|
|
<dl>
|
|
<dt><b>Structure constants</b></dt>
|
|
|
|
<dd>Structure constants are represented with notation similar to structure
|
|
type definitions (a comma separated list of elements, surrounded by braces
|
|
(<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
|
|
where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
|
|
must have <a href="#t_struct">structure type</a>, and the number and
|
|
types of elements must match those specified by the type.
|
|
</dd>
|
|
|
|
<dt><b>Array constants</b></dt>
|
|
|
|
<dd>Array constants are represented with notation similar to array type
|
|
definitions (a comma separated list of elements, surrounded by square brackets
|
|
(<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
|
|
constants must have <a href="#t_array">array type</a>, and the number and
|
|
types of elements must match those specified by the type.
|
|
</dd>
|
|
|
|
<dt><b>Vector constants</b></dt>
|
|
|
|
<dd>Vector constants are represented with notation similar to vector type
|
|
definitions (a comma separated list of elements, surrounded by
|
|
less-than/greater-than's (<tt><></tt>)). For example: "<tt>< i32 42,
|
|
i32 11, i32 74, i32 100 ></tt>". Vector constants must have <a
|
|
href="#t_vector">vector type</a>, and the number and types of elements must
|
|
match those specified by the type.
|
|
</dd>
|
|
|
|
<dt><b>Zero initialization</b></dt>
|
|
|
|
<dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
|
|
value to zero of <em>any</em> type, including scalar and aggregate types.
|
|
This is often used to avoid having to print large zero initializers (e.g. for
|
|
large arrays) and is always exactly equivalent to using explicit zero
|
|
initializers.
|
|
</dd>
|
|
</dl>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="globalconstants">Global Variable and Function Addresses</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The addresses of <a href="#globalvars">global variables</a> and <a
|
|
href="#functionstructure">functions</a> are always implicitly valid (link-time)
|
|
constants. These constants are explicitly referenced when the <a
|
|
href="#identifiers">identifier for the global</a> is used and always have <a
|
|
href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
|
|
file:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
@X = global i32 17
|
|
@Y = global i32 42
|
|
@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
|
|
</pre>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
|
|
<div class="doc_text">
|
|
<p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
|
|
no specific value. Undefined values may be of any type and be used anywhere
|
|
a constant is permitted.</p>
|
|
|
|
<p>Undefined values indicate to the compiler that the program is well defined
|
|
no matter what value is used, giving the compiler more freedom to optimize.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Constant expressions are used to allow expressions involving other constants
|
|
to be used as constants. Constant expressions may be of any <a
|
|
href="#t_firstclass">first class</a> type and may involve any LLVM operation
|
|
that does not have side effects (e.g. load and call are not supported). The
|
|
following is the syntax for constant expressions:</p>
|
|
|
|
<dl>
|
|
<dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
|
|
<dd>Truncate a constant to another type. The bit size of CST must be larger
|
|
than the bit size of TYPE. Both types must be integers.</dd>
|
|
|
|
<dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
|
|
<dd>Zero extend a constant to another type. The bit size of CST must be
|
|
smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
|
|
|
|
<dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
|
|
<dd>Sign extend a constant to another type. The bit size of CST must be
|
|
smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
|
|
|
|
<dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
|
|
<dd>Truncate a floating point constant to another floating point type. The
|
|
size of CST must be larger than the size of TYPE. Both types must be
|
|
floating point.</dd>
|
|
|
|
<dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
|
|
<dd>Floating point extend a constant to another type. The size of CST must be
|
|
smaller or equal to the size of TYPE. Both types must be floating point.</dd>
|
|
|
|
<dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a floating point constant to the corresponding unsigned integer
|
|
constant. TYPE must be a scalar or vector integer type. CST must be of scalar
|
|
or vector floating point type. Both CST and TYPE must be scalars, or vectors
|
|
of the same number of elements. If the value won't fit in the integer type,
|
|
the results are undefined.</dd>
|
|
|
|
<dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a floating point constant to the corresponding signed integer
|
|
constant. TYPE must be a scalar or vector integer type. CST must be of scalar
|
|
or vector floating point type. Both CST and TYPE must be scalars, or vectors
|
|
of the same number of elements. If the value won't fit in the integer type,
|
|
the results are undefined.</dd>
|
|
|
|
<dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert an unsigned integer constant to the corresponding floating point
|
|
constant. TYPE must be a scalar or vector floating point type. CST must be of
|
|
scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
|
|
of the same number of elements. If the value won't fit in the floating point
|
|
type, the results are undefined.</dd>
|
|
|
|
<dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a signed integer constant to the corresponding floating point
|
|
constant. TYPE must be a scalar or vector floating point type. CST must be of
|
|
scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
|
|
of the same number of elements. If the value won't fit in the floating point
|
|
type, the results are undefined.</dd>
|
|
|
|
<dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a pointer typed constant to the corresponding integer constant
|
|
TYPE must be an integer type. CST must be of pointer type. The CST value is
|
|
zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
|
|
|
|
<dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a integer constant to a pointer constant. TYPE must be a
|
|
pointer type. CST must be of integer type. The CST value is zero extended,
|
|
truncated, or unchanged to make it fit in a pointer size. This one is
|
|
<i>really</i> dangerous!</dd>
|
|
|
|
<dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
|
|
<dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
|
|
identical (same number of bits). The conversion is done as if the CST value
|
|
was stored to memory and read back as TYPE. In other words, no bits change
|
|
with this operator, just the type. This can be used for conversion of
|
|
vector types to any other type, as long as they have the same bit width. For
|
|
pointers it is only valid to cast to another pointer type. It is not valid
|
|
to bitcast to or from an aggregate type.
|
|
</dd>
|
|
|
|
<dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
|
|
|
|
<dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
|
|
constants. As with the <a href="#i_getelementptr">getelementptr</a>
|
|
instruction, the index list may have zero or more indexes, which are required
|
|
to make sense for the type of "CSTPTR".</dd>
|
|
|
|
<dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
|
|
|
|
<dd>Perform the <a href="#i_select">select operation</a> on
|
|
constants.</dd>
|
|
|
|
<dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
|
|
<dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
|
|
<dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>vicmp COND ( VAL1, VAL2 )</tt></b></dt>
|
|
<dd>Performs the <a href="#i_vicmp">vicmp operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>vfcmp COND ( VAL1, VAL2 )</tt></b></dt>
|
|
<dd>Performs the <a href="#i_vfcmp">vfcmp operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
|
|
|
|
<dd>Perform the <a href="#i_extractelement">extractelement
|
|
operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
|
|
|
|
<dd>Perform the <a href="#i_insertelement">insertelement
|
|
operation</a> on constants.</dd>
|
|
|
|
|
|
<dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
|
|
|
|
<dd>Perform the <a href="#i_shufflevector">shufflevector
|
|
operation</a> on constants.</dd>
|
|
|
|
<dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
|
|
|
|
<dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
|
|
be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
|
|
binary</a> operations. The constraints on operands are the same as those for
|
|
the corresponding instruction (e.g. no bitwise operations on floating point
|
|
values are allowed).</dd>
|
|
</dl>
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="inlineasm">Inline Assembler Expressions</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>
|
|
LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
|
|
Module-Level Inline Assembly</a>) through the use of a special value. This
|
|
value represents the inline assembler as a string (containing the instructions
|
|
to emit), a list of operand constraints (stored as a string), and a flag that
|
|
indicates whether or not the inline asm expression has side effects. An example
|
|
inline assembler expression is:
|
|
</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
i32 (i32) asm "bswap $0", "=r,r"
|
|
</pre>
|
|
</div>
|
|
|
|
<p>
|
|
Inline assembler expressions may <b>only</b> be used as the callee operand of
|
|
a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
|
|
</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
|
|
</pre>
|
|
</div>
|
|
|
|
<p>
|
|
Inline asms with side effects not visible in the constraint list must be marked
|
|
as having side effects. This is done through the use of the
|
|
'<tt>sideeffect</tt>' keyword, like so:
|
|
</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
call void asm sideeffect "eieio", ""()
|
|
</pre>
|
|
</div>
|
|
|
|
<p>TODO: The format of the asm and constraints string still need to be
|
|
documented here. Constraints on what can be done (e.g. duplication, moving, etc
|
|
need to be documented). This is probably best done by reference to another
|
|
document that covers inline asm from a holistic perspective.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The LLVM instruction set consists of several different
|
|
classifications of instructions: <a href="#terminators">terminator
|
|
instructions</a>, <a href="#binaryops">binary instructions</a>,
|
|
<a href="#bitwiseops">bitwise binary instructions</a>, <a
|
|
href="#memoryops">memory instructions</a>, and <a href="#otherops">other
|
|
instructions</a>.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="terminators">Terminator
|
|
Instructions</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>As mentioned <a href="#functionstructure">previously</a>, every
|
|
basic block in a program ends with a "Terminator" instruction, which
|
|
indicates which block should be executed after the current block is
|
|
finished. These terminator instructions typically yield a '<tt>void</tt>'
|
|
value: they produce control flow, not values (the one exception being
|
|
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
|
|
<p>There are six different terminator instructions: the '<a
|
|
href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
|
|
instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
|
|
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
|
|
href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
|
|
href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
ret <type> <value> <i>; Return a value from a non-void function</i>
|
|
ret void <i>; Return from void function</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>ret</tt>' instruction is used to return control flow (and
|
|
optionally a value) from a function back to the caller.</p>
|
|
<p>There are two forms of the '<tt>ret</tt>' instruction: one that
|
|
returns a value and then causes control flow, and one that just causes
|
|
control flow to occur.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The '<tt>ret</tt>' instruction optionally accepts a single argument,
|
|
the return value. The type of the return value must be a
|
|
'<a href="#t_firstclass">first class</a>' type.</p>
|
|
|
|
<p>A function is not <a href="#wellformed">well formed</a> if
|
|
it it has a non-void return type and contains a '<tt>ret</tt>'
|
|
instruction with no return value or a return value with a type that
|
|
does not match its type, or if it has a void return type and contains
|
|
a '<tt>ret</tt>' instruction with a return value.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>When the '<tt>ret</tt>' instruction is executed, control flow
|
|
returns back to the calling function's context. If the caller is a "<a
|
|
href="#i_call"><tt>call</tt></a>" instruction, execution continues at
|
|
the instruction after the call. If the caller was an "<a
|
|
href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
|
|
at the beginning of the "normal" destination block. If the instruction
|
|
returns a value, that value shall set the call or invoke instruction's
|
|
return value.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
ret i32 5 <i>; Return an integer value of 5</i>
|
|
ret void <i>; Return from a void function</i>
|
|
ret { i32, i8 } { i32 4, i8 2 } <i>; Return an aggregate of values 4 and 2</i>
|
|
</pre>
|
|
|
|
<p>Note that the code generator does not yet fully support large
|
|
return values. The specific sizes that are currently supported are
|
|
dependent on the target. For integers, on 32-bit targets the limit
|
|
is often 64 bits, and on 64-bit targets the limit is often 128 bits.
|
|
For aggregate types, the current limits are dependent on the element
|
|
types; for example targets are often limited to 2 total integer
|
|
elements and 2 total floating-point elements.</p>
|
|
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> br i1 <cond>, label <iftrue>, label <iffalse><br> br label <dest> <i>; Unconditional branch</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>br</tt>' instruction is used to cause control flow to
|
|
transfer to a different basic block in the current function. There are
|
|
two forms of this instruction, corresponding to a conditional branch
|
|
and an unconditional branch.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
|
|
single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
|
|
unconditional form of the '<tt>br</tt>' instruction takes a single
|
|
'<tt>label</tt>' value as a target.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
|
|
argument is evaluated. If the value is <tt>true</tt>, control flows
|
|
to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
|
|
control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
|
|
<h5>Example:</h5>
|
|
<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
|
|
href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_switch">'<tt>switch</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
switch <intty> <value>, label <defaultdest> [ <intty> <val>, label <dest> ... ]
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
|
|
several different places. It is a generalization of the '<tt>br</tt>'
|
|
instruction, allowing a branch to occur to one of many possible
|
|
destinations.</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
|
|
comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
|
|
an array of pairs of comparison value constants and '<tt>label</tt>'s. The
|
|
table is not allowed to contain duplicate constant entries.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The <tt>switch</tt> instruction specifies a table of values and
|
|
destinations. When the '<tt>switch</tt>' instruction is executed, this
|
|
table is searched for the given value. If the value is found, control flow is
|
|
transfered to the corresponding destination; otherwise, control flow is
|
|
transfered to the default destination.</p>
|
|
|
|
<h5>Implementation:</h5>
|
|
|
|
<p>Depending on properties of the target machine and the particular
|
|
<tt>switch</tt> instruction, this instruction may be code generated in different
|
|
ways. For example, it could be generated as a series of chained conditional
|
|
branches or with a lookup table.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
<i>; Emulate a conditional br instruction</i>
|
|
%Val = <a href="#i_zext">zext</a> i1 %value to i32
|
|
switch i32 %Val, label %truedest [ i32 0, label %falsedest ]
|
|
|
|
<i>; Emulate an unconditional br instruction</i>
|
|
switch i32 0, label %dest [ ]
|
|
|
|
<i>; Implement a jump table:</i>
|
|
switch i32 %val, label %otherwise [ i32 0, label %onzero
|
|
i32 1, label %onone
|
|
i32 2, label %ontwo ]
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = invoke [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ptr to function ty> <function ptr val>(<function args>) [<a href="#fnattrs">fn attrs</a>]
|
|
to label <normal label> unwind label <exception label>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
|
|
function, with the possibility of control flow transfer to either the
|
|
'<tt>normal</tt>' label or the
|
|
'<tt>exception</tt>' label. If the callee function returns with the
|
|
"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
|
|
"normal" label. If the callee (or any indirect callees) returns with the "<a
|
|
href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
|
|
continued at the dynamically nearest "exception" label.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>This instruction requires several arguments:</p>
|
|
|
|
<ol>
|
|
<li>
|
|
The optional "cconv" marker indicates which <a href="#callingconv">calling
|
|
convention</a> the call should use. If none is specified, the call defaults
|
|
to using C calling conventions.
|
|
</li>
|
|
|
|
<li>The optional <a href="#paramattrs">Parameter Attributes</a> list for
|
|
return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>',
|
|
and '<tt>inreg</tt>' attributes are valid here.</li>
|
|
|
|
<li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
|
|
function value being invoked. In most cases, this is a direct function
|
|
invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
|
|
an arbitrary pointer to function value.
|
|
</li>
|
|
|
|
<li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
|
|
function to be invoked. </li>
|
|
|
|
<li>'<tt>function args</tt>': argument list whose types match the function
|
|
signature argument types. If the function signature indicates the function
|
|
accepts a variable number of arguments, the extra arguments can be
|
|
specified. </li>
|
|
|
|
<li>'<tt>normal label</tt>': the label reached when the called function
|
|
executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
|
|
|
|
<li>'<tt>exception label</tt>': the label reached when a callee returns with
|
|
the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
|
|
|
|
<li>The optional <a href="#fnattrs">function attributes</a> list. Only
|
|
'<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
|
|
'<tt>readnone</tt>' attributes are valid here.</li>
|
|
</ol>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>This instruction is designed to operate as a standard '<tt><a
|
|
href="#i_call">call</a></tt>' instruction in most regards. The primary
|
|
difference is that it establishes an association with a label, which is used by
|
|
the runtime library to unwind the stack.</p>
|
|
|
|
<p>This instruction is used in languages with destructors to ensure that proper
|
|
cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
|
|
exception. Additionally, this is important for implementation of
|
|
'<tt>catch</tt>' clauses in high-level languages that support them.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%retval = invoke i32 @Test(i32 15) to label %Continue
|
|
unwind label %TestCleanup <i>; {i32}:retval set</i>
|
|
%retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
|
|
unwind label %TestCleanup <i>; {i32}:retval set</i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
|
|
<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
|
|
Instruction</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
unwind
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
|
|
at the first callee in the dynamic call stack which used an <a
|
|
href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
|
|
primarily used to implement exception handling.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>unwind</tt>' instruction causes execution of the current function to
|
|
immediately halt. The dynamic call stack is then searched for the first <a
|
|
href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
|
|
execution continues at the "exceptional" destination block specified by the
|
|
<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
|
|
dynamic call chain, undefined behavior results.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
|
|
<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
|
|
Instruction</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
unreachable
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
|
|
instruction is used to inform the optimizer that a particular portion of the
|
|
code is not reachable. This can be used to indicate that the code after a
|
|
no-return function cannot be reached, and other facts.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
|
|
</div>
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
|
|
<div class="doc_text">
|
|
<p>Binary operators are used to do most of the computation in a
|
|
program. They require two operands of the same type, execute an operation on them, and
|
|
produce a single value. The operands might represent
|
|
multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
|
|
The result value has the same type as its operands.</p>
|
|
<p>There are several different binary operators:</p>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_add">'<tt>add</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = add <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>add</tt>' instruction must be <a
|
|
href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>, or
|
|
<a href="#t_vector">vector</a> values. Both arguments must have identical
|
|
types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is the integer or floating point sum of the two
|
|
operands.</p>
|
|
|
|
<p>If an integer sum has unsigned overflow, the result returned is the
|
|
mathematical result modulo 2<sup>n</sup>, where n is the bit width of
|
|
the result.</p>
|
|
|
|
<p>Because LLVM integers use a two's complement representation, this
|
|
instruction is appropriate for both signed and unsigned integers.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
<result> = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_sub">'<tt>sub</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = sub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>sub</tt>' instruction returns the difference of its two
|
|
operands.</p>
|
|
|
|
<p>Note that the '<tt>sub</tt>' instruction is used to represent the
|
|
'<tt>neg</tt>' instruction present in most other intermediate
|
|
representations.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>sub</tt>' instruction must be <a
|
|
href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>,
|
|
or <a href="#t_vector">vector</a> values. Both arguments must have identical
|
|
types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is the integer or floating point difference of
|
|
the two operands.</p>
|
|
|
|
<p>If an integer difference has unsigned overflow, the result returned is the
|
|
mathematical result modulo 2<sup>n</sup>, where n is the bit width of
|
|
the result.</p>
|
|
|
|
<p>Because LLVM integers use a two's complement representation, this
|
|
instruction is appropriate for both signed and unsigned integers.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<result> = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
|
|
<result> = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_mul">'<tt>mul</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = mul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>mul</tt>' instruction returns the product of its two
|
|
operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>mul</tt>' instruction must be <a
|
|
href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>,
|
|
or <a href="#t_vector">vector</a> values. Both arguments must have identical
|
|
types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is the integer or floating point product of the
|
|
two operands.</p>
|
|
|
|
<p>If the result of an integer multiplication has unsigned overflow,
|
|
the result returned is the mathematical result modulo
|
|
2<sup>n</sup>, where n is the bit width of the result.</p>
|
|
<p>Because LLVM integers use a two's complement representation, and the
|
|
result is the same width as the operands, this instruction returns the
|
|
correct result for both signed and unsigned integers. If a full product
|
|
(e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands
|
|
should be sign-extended or zero-extended as appropriate to the
|
|
width of the full product.</p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
|
|
</a></div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = udiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
|
|
operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>udiv</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is the unsigned integer quotient of the two operands.</p>
|
|
<p>Note that unsigned integer division and signed integer division are distinct
|
|
operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
|
|
<p>Division by zero leads to undefined behavior.</p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
|
|
</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = sdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
|
|
operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The value produced is the signed integer quotient of the two operands rounded towards zero.</p>
|
|
<p>Note that signed integer division and unsigned integer division are distinct
|
|
operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
|
|
<p>Division by zero leads to undefined behavior. Overflow also leads to
|
|
undefined behavior; this is a rare case, but can occur, for example,
|
|
by doing a 32-bit division of -2147483648 by -1.</p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = fdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
|
|
operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
|
|
<a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
|
|
of floating point values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is the floating point quotient of the two operands.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
<result> = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = urem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>urem</tt>' instruction returns the remainder from the
|
|
unsigned division of its two arguments.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The two arguments to the '<tt>urem</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
|
|
This instruction always performs an unsigned division to get the remainder.</p>
|
|
<p>Note that unsigned integer remainder and signed integer remainder are
|
|
distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
|
|
<p>Taking the remainder of a division by zero leads to undefined behavior.</p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
|
|
</pre>
|
|
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_srem">'<tt>srem</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = srem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>srem</tt>' instruction returns the remainder from the
|
|
signed division of its two operands. This instruction can also take
|
|
<a href="#t_vector">vector</a> versions of the values in which case
|
|
the elements must be integers.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>srem</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>This instruction returns the <i>remainder</i> of a division (where the result
|
|
has the same sign as the dividend, <tt>op1</tt>), not the <i>modulo</i>
|
|
operator (where the result has the same sign as the divisor, <tt>op2</tt>) of
|
|
a value. For more information about the difference, see <a
|
|
href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
|
|
Math Forum</a>. For a table of how this is implemented in various languages,
|
|
please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
|
|
Wikipedia: modulo operation</a>.</p>
|
|
<p>Note that signed integer remainder and unsigned integer remainder are
|
|
distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
|
|
<p>Taking the remainder of a division by zero leads to undefined behavior.
|
|
Overflow also leads to undefined behavior; this is a rare case, but can occur,
|
|
for example, by taking the remainder of a 32-bit division of -2147483648 by -1.
|
|
(The remainder doesn't actually overflow, but this rule lets srem be
|
|
implemented using instructions that return both the result of the division
|
|
and the remainder.)</p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
|
|
</pre>
|
|
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_frem">'<tt>frem</tt>' Instruction</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = frem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>frem</tt>' instruction returns the remainder from the
|
|
division of its two operands.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The two arguments to the '<tt>frem</tt>' instruction must be
|
|
<a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
|
|
of floating point values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>This instruction returns the <i>remainder</i> of a division.
|
|
The remainder has the same sign as the dividend.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
<result> = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
|
|
Operations</a> </div>
|
|
<div class="doc_text">
|
|
<p>Bitwise binary operators are used to do various forms of
|
|
bit-twiddling in a program. They are generally very efficient
|
|
instructions and can commonly be strength reduced from other
|
|
instructions. They require two operands of the same type, execute an operation on them,
|
|
and produce a single value. The resulting value is the same type as its operands.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = shl <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
|
|
the left a specified number of bits.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
|
|
href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
type. '<tt>op2</tt>' is treated as an unsigned value.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The value produced is <tt>op1</tt> * 2<sup><tt>op2</tt></sup> mod 2<sup>n</sup>,
|
|
where n is the width of the result. If <tt>op2</tt> is (statically or dynamically) negative or
|
|
equal to or larger than the number of bits in <tt>op1</tt>, the result is undefined.
|
|
If the arguments are vectors, each vector element of <tt>op1</tt> is shifted by the
|
|
corresponding shift amount in <tt>op2</tt>.</p>
|
|
|
|
<h5>Example:</h5><pre>
|
|
<result> = shl i32 4, %var <i>; yields {i32}: 4 << %var</i>
|
|
<result> = shl i32 4, 2 <i>; yields {i32}: 16</i>
|
|
<result> = shl i32 1, 10 <i>; yields {i32}: 1024</i>
|
|
<result> = shl i32 1, 32 <i>; undefined</i>
|
|
<result> = shl <2 x i32> < i32 1, i32 1>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 2, i32 4></i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = lshr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
|
|
operand shifted to the right a specified number of bits with zero fill.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
type. '<tt>op2</tt>' is treated as an unsigned value.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>This instruction always performs a logical shift right operation. The most
|
|
significant bits of the result will be filled with zero bits after the
|
|
shift. If <tt>op2</tt> is (statically or dynamically) equal to or larger than
|
|
the number of bits in <tt>op1</tt>, the result is undefined. If the arguments are
|
|
vectors, each vector element of <tt>op1</tt> is shifted by the corresponding shift
|
|
amount in <tt>op2</tt>.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<result> = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
|
|
<result> = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
|
|
<result> = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
|
|
<result> = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
|
|
<result> = lshr i32 1, 32 <i>; undefined</i>
|
|
<result> = lshr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 0x7FFFFFFF, i32 1></i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = ashr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
|
|
operand shifted to the right a specified number of bits with sign extension.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
type. '<tt>op2</tt>' is treated as an unsigned value.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>This instruction always performs an arithmetic shift right operation,
|
|
The most significant bits of the result will be filled with the sign bit
|
|
of <tt>op1</tt>. If <tt>op2</tt> is (statically or dynamically) equal to or
|
|
larger than the number of bits in <tt>op1</tt>, the result is undefined. If the
|
|
arguments are vectors, each vector element of <tt>op1</tt> is shifted by the
|
|
corresponding shift amount in <tt>op2</tt>.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<result> = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
|
|
<result> = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
|
|
<result> = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
|
|
<result> = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
|
|
<result> = ashr i32 1, 32 <i>; undefined</i>
|
|
<result> = ashr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 3> <i>; yields: result=<2 x i32> < i32 -1, i32 0></i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
|
|
Instruction</a> </div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = and <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
|
|
its two operands.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>and</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
|
|
<p> </p>
|
|
<div>
|
|
<table border="1" cellspacing="0" cellpadding="4">
|
|
<tbody>
|
|
<tr>
|
|
<td>In0</td>
|
|
<td>In1</td>
|
|
<td>Out</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>1</td>
|
|
<td>0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<result> = and i32 4, %var <i>; yields {i32}:result = 4 & %var</i>
|
|
<result> = and i32 15, 40 <i>; yields {i32}:result = 8</i>
|
|
<result> = and i32 4, 8 <i>; yields {i32}:result = 0</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = or <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
|
|
or of its two operands.</p>
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The two arguments to the '<tt>or</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
|
|
<p> </p>
|
|
<div>
|
|
<table border="1" cellspacing="0" cellpadding="4">
|
|
<tbody>
|
|
<tr>
|
|
<td>In0</td>
|
|
<td>In1</td>
|
|
<td>Out</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>0</td>
|
|
<td>1</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
|
|
<result> = or i32 15, 40 <i>; yields {i32}:result = 47</i>
|
|
<result> = or i32 4, 8 <i>; yields {i32}:result = 12</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = xor <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
|
|
or of its two operands. The <tt>xor</tt> is used to implement the
|
|
"one's complement" operation, which is the "~" operator in C.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The two arguments to the '<tt>xor</tt>' instruction must be
|
|
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
|
|
values. Both arguments must have identical types.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
|
|
<p> </p>
|
|
<div>
|
|
<table border="1" cellspacing="0" cellpadding="4">
|
|
<tbody>
|
|
<tr>
|
|
<td>In0</td>
|
|
<td>In1</td>
|
|
<td>Out</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
<td>0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>0</td>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>0</td>
|
|
<td>1</td>
|
|
</tr>
|
|
<tr>
|
|
<td>1</td>
|
|
<td>1</td>
|
|
<td>0</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<p> </p>
|
|
<h5>Example:</h5>
|
|
<pre> <result> = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
|
|
<result> = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
|
|
<result> = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
|
|
<result> = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="vectorops">Vector Operations</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM supports several instructions to represent vector operations in a
|
|
target-independent manner. These instructions cover the element-access and
|
|
vector-specific operations needed to process vectors effectively. While LLVM
|
|
does directly support these vector operations, many sophisticated algorithms
|
|
will want to use target-specific intrinsics to take full advantage of a specific
|
|
target.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = extractelement <n x <ty>> <val>, i32 <idx> <i>; yields <ty></i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>extractelement</tt>' instruction extracts a single scalar
|
|
element from a vector at a specified index.
|
|
</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first operand of an '<tt>extractelement</tt>' instruction is a
|
|
value of <a href="#t_vector">vector</a> type. The second operand is
|
|
an index indicating the position from which to extract the element.
|
|
The index may be a variable.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The result is a scalar of the same type as the element type of
|
|
<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
|
|
<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
|
|
results are undefined.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%result = extractelement <4 x i32> %vec, i32 0 <i>; yields i32</i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> <i>; yields <n x <ty>></i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>insertelement</tt>' instruction inserts a scalar
|
|
element into a vector at a specified index.
|
|
</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first operand of an '<tt>insertelement</tt>' instruction is a
|
|
value of <a href="#t_vector">vector</a> type. The second operand is a
|
|
scalar value whose type must equal the element type of the first
|
|
operand. The third operand is an index indicating the position at
|
|
which to insert the value. The index may be a variable.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The result is a vector of the same type as <tt>val</tt>. Its
|
|
element values are those of <tt>val</tt> except at position
|
|
<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
|
|
exceeds the length of <tt>val</tt>, the results are undefined.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%result = insertelement <4 x i32> %vec, i32 1, i32 0 <i>; yields <4 x i32></i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <m x i32> <mask> <i>; yields <m x <ty>></i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
|
|
from two input vectors, returning a vector with the same element type as
|
|
the input and length that is the same as the shuffle mask.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
|
|
with types that match each other. The third argument is a shuffle mask whose
|
|
element type is always 'i32'. The result of the instruction is a vector whose
|
|
length is the same as the shuffle mask and whose element type is the same as
|
|
the element type of the first two operands.
|
|
</p>
|
|
|
|
<p>
|
|
The shuffle mask operand is required to be a constant vector with either
|
|
constant integer or undef values.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The elements of the two input vectors are numbered from left to right across
|
|
both of the vectors. The shuffle mask operand specifies, for each element of
|
|
the result vector, which element of the two input vectors the result element
|
|
gets. The element selector may be undef (meaning "don't care") and the second
|
|
operand may be undef if performing a shuffle from only one vector.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
|
|
<4 x i32> <i32 0, i32 4, i32 1, i32 5> <i>; yields <4 x i32></i>
|
|
%result = shufflevector <4 x i32> %v1, <4 x i32> undef,
|
|
<4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i> - Identity shuffle.
|
|
%result = shufflevector <8 x i32> %v1, <8 x i32> undef,
|
|
<4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i>
|
|
%result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
|
|
<8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7 > <i>; yields <8 x i32></i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="aggregateops">Aggregate Operations</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM supports several instructions for working with aggregate values.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_extractvalue">'<tt>extractvalue</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = extractvalue <aggregate type> <val>, <idx>{, <idx>}*
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>extractvalue</tt>' instruction extracts the value of a struct field
|
|
or array element from an aggregate value.
|
|
</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first operand of an '<tt>extractvalue</tt>' instruction is a
|
|
value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a>
|
|
type. The operands are constant indices to specify which value to extract
|
|
in a similar manner as indices in a
|
|
'<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The result is the value at the position in the aggregate specified by
|
|
the index operands.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%result = extractvalue {i32, float} %agg, 0 <i>; yields i32</i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_insertvalue">'<tt>insertvalue</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = insertvalue <aggregate type> <val>, <ty> <val>, <idx> <i>; yields <n x <ty>></i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>insertvalue</tt>' instruction inserts a value
|
|
into a struct field or array element in an aggregate.
|
|
</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first operand of an '<tt>insertvalue</tt>' instruction is a
|
|
value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a> type.
|
|
The second operand is a first-class value to insert.
|
|
The following operands are constant indices
|
|
indicating the position at which to insert the value in a similar manner as
|
|
indices in a
|
|
'<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
|
|
The value to insert must have the same type as the value identified
|
|
by the indices.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The result is an aggregate of the same type as <tt>val</tt>. Its
|
|
value is that of <tt>val</tt> except that the value at the position
|
|
specified by the indices is that of <tt>elt</tt>.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%result = insertvalue {i32, float} %agg, i32 1, 0 <i>; yields {i32, float}</i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="memoryops">Memory Access and Addressing Operations</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>A key design point of an SSA-based representation is how it
|
|
represents memory. In LLVM, no memory locations are in SSA form, which
|
|
makes things very simple. This section describes how to read, write,
|
|
allocate, and free memory in LLVM.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = malloc <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>malloc</tt>' instruction allocates memory from the system
|
|
heap and returns a pointer to it. The object is always allocated in the generic
|
|
address space (address space zero).</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The '<tt>malloc</tt>' instruction allocates
|
|
<tt>sizeof(<type>)*NumElements</tt>
|
|
bytes of memory from the operating system and returns a pointer of the
|
|
appropriate type to the program. If "NumElements" is specified, it is the
|
|
number of elements allocated, otherwise "NumElements" is defaulted to be one.
|
|
If a constant alignment is specified, the value result of the allocation is guaranteed to
|
|
be aligned to at least that boundary. If not specified, or if zero, the target can
|
|
choose to align the allocation on any convenient boundary.</p>
|
|
|
|
<p>'<tt>type</tt>' must be a sized type.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
|
|
a pointer is returned. The result of a zero byte allocation is undefined. The
|
|
result is null if there is insufficient memory available.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%array = malloc [4 x i8] <i>; yields {[%4 x i8]*}:array</i>
|
|
|
|
%size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
|
|
%array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
|
|
%array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
|
|
%array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
|
|
%array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
|
|
</pre>
|
|
|
|
<p>Note that the code generator does not yet respect the
|
|
alignment value.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_free">'<tt>free</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
free <type> <value> <i>; yields {void}</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>free</tt>' instruction returns memory back to the unused
|
|
memory heap to be reallocated in the future.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>'<tt>value</tt>' shall be a pointer value that points to a value
|
|
that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
|
|
instruction.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>Access to the memory pointed to by the pointer is no longer defined
|
|
after this instruction executes. If the pointer is null, the operation
|
|
is a noop.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
|
|
free [4 x i8]* %array
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = alloca <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
|
|
currently executing function, to be automatically released when this function
|
|
returns to its caller. The object is always allocated in the generic address
|
|
space (address space zero).</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
|
|
bytes of memory on the runtime stack, returning a pointer of the
|
|
appropriate type to the program. If "NumElements" is specified, it is the
|
|
number of elements allocated, otherwise "NumElements" is defaulted to be one.
|
|
If a constant alignment is specified, the value result of the allocation is guaranteed
|
|
to be aligned to at least that boundary. If not specified, or if zero, the target
|
|
can choose to align the allocation on any convenient boundary.</p>
|
|
|
|
<p>'<tt>type</tt>' may be any sized type.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>Memory is allocated; a pointer is returned. The operation is undefiend if
|
|
there is insufficient stack space for the allocation. '<tt>alloca</tt>'d
|
|
memory is automatically released when the function returns. The '<tt>alloca</tt>'
|
|
instruction is commonly used to represent automatic variables that must
|
|
have an address available. When the function returns (either with the <tt><a
|
|
href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
|
|
instructions), the memory is reclaimed. Allocating zero bytes
|
|
is legal, but the result is undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%ptr = alloca i32 <i>; yields {i32*}:ptr</i>
|
|
%ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
|
|
%ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
|
|
%ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = load <ty>* <pointer>[, align <alignment>]<br> <result> = volatile load <ty>* <pointer>[, align <alignment>]<br></pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The argument to the '<tt>load</tt>' instruction specifies the memory
|
|
address from which to load. The pointer must point to a <a
|
|
href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
|
|
marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
|
|
the number or order of execution of this <tt>load</tt> with other
|
|
volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
|
|
instructions. </p>
|
|
<p>
|
|
The optional constant "align" argument specifies the alignment of the operation
|
|
(that is, the alignment of the memory address). A value of 0 or an
|
|
omitted "align" argument means that the operation has the preferential
|
|
alignment for the target. It is the responsibility of the code emitter
|
|
to ensure that the alignment information is correct. Overestimating
|
|
the alignment results in an undefined behavior. Underestimating the
|
|
alignment may produce less efficient code. An alignment of 1 is always
|
|
safe.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The location of memory pointed to is loaded.</p>
|
|
<h5>Examples:</h5>
|
|
<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
|
|
<a
|
|
href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
|
|
%val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
|
|
</pre>
|
|
</div>
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
|
|
Instruction</a> </div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
|
|
volatile store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>There are two arguments to the '<tt>store</tt>' instruction: a value
|
|
to store and an address at which to store it. The type of the '<tt><pointer></tt>'
|
|
operand must be a pointer to the <a href="#t_firstclass">first class</a> type
|
|
of the '<tt><value></tt>'
|
|
operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
|
|
optimizer is not allowed to modify the number or order of execution of
|
|
this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
|
|
href="#i_store">store</a></tt> instructions.</p>
|
|
<p>
|
|
The optional constant "align" argument specifies the alignment of the operation
|
|
(that is, the alignment of the memory address). A value of 0 or an
|
|
omitted "align" argument means that the operation has the preferential
|
|
alignment for the target. It is the responsibility of the code emitter
|
|
to ensure that the alignment information is correct. Overestimating
|
|
the alignment results in an undefined behavior. Underestimating the
|
|
alignment may produce less efficient code. An alignment of 1 is always
|
|
safe.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The contents of memory are updated to contain '<tt><value></tt>'
|
|
at the location specified by the '<tt><pointer></tt>' operand.</p>
|
|
<h5>Example:</h5>
|
|
<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
|
|
store i32 3, i32* %ptr <i>; yields {void}</i>
|
|
%val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = getelementptr <pty>* <ptrval>{, <ty> <idx>}*
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>getelementptr</tt>' instruction is used to get the address of a
|
|
subelement of an aggregate data structure. It performs address calculation only
|
|
and does not access memory.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The first argument is always a pointer, and forms the basis of the
|
|
calculation. The remaining arguments are indices, that indicate which of the
|
|
elements of the aggregate object are indexed. The interpretation of each index
|
|
is dependent on the type being indexed into. The first index always indexes the
|
|
pointer value given as the first argument, the second index indexes a value of
|
|
the type pointed to (not necessarily the value directly pointed to, since the
|
|
first index can be non-zero), etc. The first type indexed into must be a pointer
|
|
value, subsequent types can be arrays, vectors and structs. Note that subsequent
|
|
types being indexed into can never be pointers, since that would require loading
|
|
the pointer before continuing calculation.</p>
|
|
|
|
<p>The type of each index argument depends on the type it is indexing into.
|
|
When indexing into a (packed) structure, only <tt>i32</tt> integer
|
|
<b>constants</b> are allowed. When indexing into an array, pointer or vector,
|
|
only integers of 32 or 64 bits are allowed (also non-constants). 32-bit values
|
|
will be sign extended to 64-bits if required.</p>
|
|
|
|
<p>For example, let's consider a C code fragment and how it gets
|
|
compiled to LLVM:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
struct RT {
|
|
char A;
|
|
int B[10][20];
|
|
char C;
|
|
};
|
|
struct ST {
|
|
int X;
|
|
double Y;
|
|
struct RT Z;
|
|
};
|
|
|
|
int *foo(struct ST *s) {
|
|
return &s[1].Z.B[5][13];
|
|
}
|
|
</pre>
|
|
</div>
|
|
|
|
<p>The LLVM code generated by the GCC frontend is:</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
%RT = <a href="#namedtypes">type</a> { i8 , [10 x [20 x i32]], i8 }
|
|
%ST = <a href="#namedtypes">type</a> { i32, double, %RT }
|
|
|
|
define i32* %foo(%ST* %s) {
|
|
entry:
|
|
%reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
|
|
ret i32* %reg
|
|
}
|
|
</pre>
|
|
</div>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
|
|
type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
|
|
}</tt>' type, a structure. The second index indexes into the third element of
|
|
the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
|
|
i8 }</tt>' type, another structure. The third index indexes into the second
|
|
element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
|
|
array. The two dimensions of the array are subscripted into, yielding an
|
|
'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
|
|
to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
|
|
|
|
<p>Note that it is perfectly legal to index partially through a
|
|
structure, returning a pointer to an inner element. Because of this,
|
|
the LLVM code for the given testcase is equivalent to:</p>
|
|
|
|
<pre>
|
|
define i32* %foo(%ST* %s) {
|
|
%t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
|
|
%t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
|
|
%t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
|
|
%t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
|
|
%t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
|
|
ret i32* %t5
|
|
}
|
|
</pre>
|
|
|
|
<p>Note that it is undefined to access an array out of bounds: array and
|
|
pointer indexes must always be within the defined bounds of the array type.
|
|
The one exception for this rule is zero length arrays. These arrays are
|
|
defined to be accessible as variable length arrays, which requires access
|
|
beyond the zero'th element.</p>
|
|
|
|
<p>The getelementptr instruction is often confusing. For some more insight
|
|
into how it works, see <a href="GetElementPtr.html">the getelementptr
|
|
FAQ</a>.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
<i>; yields [12 x i8]*:aptr</i>
|
|
%aptr = getelementptr {i32, [12 x i8]}* %saptr, i64 0, i32 1
|
|
<i>; yields i8*:vptr</i>
|
|
%vptr = getelementptr {i32, <2 x i8>}* %svptr, i64 0, i32 1, i32 1
|
|
<i>; yields i8*:eptr</i>
|
|
%eptr = getelementptr [12 x i8]* %aptr, i64 0, i32 1
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<p>The instructions in this category are the conversion instructions (casting)
|
|
which all take a single operand and a type. They perform various bit conversions
|
|
on the operand.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = trunc <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
|
|
be an <a href="#t_integer">integer</a> type, and a type that specifies the size
|
|
and type of the result, which must be an <a href="#t_integer">integer</a>
|
|
type. The bit size of <tt>value</tt> must be larger than the bit size of
|
|
<tt>ty2</tt>. Equal sized types are not allowed.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
|
|
and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
|
|
larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
|
|
It will always truncate bits.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = trunc i32 257 to i8 <i>; yields i8:1</i>
|
|
%Y = trunc i32 123 to i1 <i>; yields i1:true</i>
|
|
%Y = trunc i32 122 to i1 <i>; yields i1:false</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = zext <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>zext</tt>' instruction zero extends its operand to type
|
|
<tt>ty2</tt>.</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
|
|
<a href="#t_integer">integer</a> type, and a type to cast it to, which must
|
|
also be of <a href="#t_integer">integer</a> type. The bit size of the
|
|
<tt>value</tt> must be smaller than the bit size of the destination type,
|
|
<tt>ty2</tt>.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
|
|
bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
|
|
|
|
<p>When zero extending from i1, the result will always be either 0 or 1.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = zext i32 257 to i64 <i>; yields i64:257</i>
|
|
%Y = zext i1 true to i32 <i>; yields i32:1</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = sext <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The '<tt>sext</tt>' instruction takes a value to cast, which must be of
|
|
<a href="#t_integer">integer</a> type, and a type to cast it to, which must
|
|
also be of <a href="#t_integer">integer</a> type. The bit size of the
|
|
<tt>value</tt> must be smaller than the bit size of the destination type,
|
|
<tt>ty2</tt>.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
|
|
bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
|
|
the type <tt>ty2</tt>.</p>
|
|
|
|
<p>When sign extending from i1, the extension always results in -1 or 0.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
|
|
%Y = sext i1 true to i32 <i>; yields i32:-1</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = fptrunc <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
|
|
<tt>ty2</tt>.</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
|
|
point</a> value to cast and a <a href="#t_floating">floating point</a> type to
|
|
cast it to. The size of <tt>value</tt> must be larger than the size of
|
|
<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
|
|
<i>no-op cast</i>.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
|
|
<a href="#t_floating">floating point</a> type to a smaller
|
|
<a href="#t_floating">floating point</a> type. If the value cannot fit within
|
|
the destination type, <tt>ty2</tt>, then the results are undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
|
|
%Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = fpext <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
|
|
floating point value.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>fpext</tt>' instruction takes a
|
|
<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
|
|
and a <a href="#t_floating">floating point</a> type to cast it to. The source
|
|
type must be smaller than the destination type.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
|
|
<a href="#t_floating">floating point</a> type to a larger
|
|
<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
|
|
used to make a <i>no-op cast</i> because it always changes bits. Use
|
|
<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
|
|
%Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = fptoui <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
|
|
unsigned integer equivalent of type <tt>ty2</tt>.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>fptoui</tt>' instruction takes a value to cast, which must be a
|
|
scalar or vector <a href="#t_floating">floating point</a> value, and a type
|
|
to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
|
|
type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
|
|
vector integer type with the same number of elements as <tt>ty</tt></p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p> The '<tt>fptoui</tt>' instruction converts its
|
|
<a href="#t_floating">floating point</a> operand into the nearest (rounding
|
|
towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
|
|
the results are undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
|
|
%Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
|
|
%X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = fptosi <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>fptosi</tt>' instruction converts
|
|
<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
|
|
scalar or vector <a href="#t_floating">floating point</a> value, and a type
|
|
to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
|
|
type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
|
|
vector integer type with the same number of elements as <tt>ty</tt></p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>fptosi</tt>' instruction converts its
|
|
<a href="#t_floating">floating point</a> operand into the nearest (rounding
|
|
towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
|
|
the results are undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
|
|
%Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
|
|
%X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = uitofp <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
|
|
integer and converts that value to the <tt>ty2</tt> type.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
|
|
scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
|
|
to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
|
|
type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
|
|
floating point type with the same number of elements as <tt>ty</tt></p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
|
|
integer quantity and converts it to the corresponding floating point value. If
|
|
the value cannot fit in the floating point value, the results are undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = uitofp i32 257 to float <i>; yields float:257.0</i>
|
|
%Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = sitofp <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
|
|
integer and converts that value to the <tt>ty2</tt> type.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
|
|
scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
|
|
to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
|
|
type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
|
|
floating point type with the same number of elements as <tt>ty</tt></p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
|
|
integer quantity and converts it to the corresponding floating point value. If
|
|
the value cannot fit in the floating point value, the results are undefined.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = sitofp i32 257 to float <i>; yields float:257.0</i>
|
|
%Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = ptrtoint <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
|
|
the integer type <tt>ty2</tt>.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
|
|
must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
|
|
<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
|
|
<tt>ty2</tt> by interpreting the pointer value as an integer and either
|
|
truncating or zero extending that value to the size of the integer type. If
|
|
<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
|
|
<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
|
|
are the same size, then nothing is done (<i>no-op cast</i>) other than a type
|
|
change.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
|
|
%Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = inttoptr <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
|
|
a pointer type, <tt>ty2</tt>.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
|
|
value to cast, and a type to cast it to, which must be a
|
|
<a href="#t_pointer">pointer</a> type.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
|
|
<tt>ty2</tt> by applying either a zero extension or a truncation depending on
|
|
the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
|
|
size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
|
|
the size of a pointer then a zero extension is done. If they are the same size,
|
|
nothing is done (<i>no-op cast</i>).</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
|
|
%X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
|
|
%Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = bitcast <ty> <value> to <ty2> <i>; yields ty2</i>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
|
|
<tt>ty2</tt> without changing any bits.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
|
|
a non-aggregate first class value, and a type to cast it to, which must also be
|
|
a non-aggregate <a href="#t_firstclass">first class</a> type. The bit sizes of
|
|
<tt>value</tt>
|
|
and the destination type, <tt>ty2</tt>, must be identical. If the source
|
|
type is a pointer, the destination type must also be a pointer. This
|
|
instruction supports bitwise conversion of vectors to integers and to vectors
|
|
of other types (as long as they have the same size).</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
|
|
<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
|
|
this conversion. The conversion is done as if the <tt>value</tt> had been
|
|
stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
|
|
converted to other pointer types with this instruction. To convert pointers to
|
|
other types, use the <a href="#i_inttoptr">inttoptr</a> or
|
|
<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
|
|
%Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
|
|
%Z = bitcast <2 x int> %V to i64; <i>; yields i64: %V</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
|
|
<div class="doc_text">
|
|
<p>The instructions in this category are the "miscellaneous"
|
|
instructions, which defy better classification.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = icmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>icmp</tt>' instruction returns a boolean value or
|
|
a vector of boolean values based on comparison
|
|
of its two integer, integer vector, or pointer operands.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
|
|
the condition code indicating the kind of comparison to perform. It is not
|
|
a value, just a keyword. The possible condition code are:
|
|
</p>
|
|
<ol>
|
|
<li><tt>eq</tt>: equal</li>
|
|
<li><tt>ne</tt>: not equal </li>
|
|
<li><tt>ugt</tt>: unsigned greater than</li>
|
|
<li><tt>uge</tt>: unsigned greater or equal</li>
|
|
<li><tt>ult</tt>: unsigned less than</li>
|
|
<li><tt>ule</tt>: unsigned less or equal</li>
|
|
<li><tt>sgt</tt>: signed greater than</li>
|
|
<li><tt>sge</tt>: signed greater or equal</li>
|
|
<li><tt>slt</tt>: signed less than</li>
|
|
<li><tt>sle</tt>: signed less or equal</li>
|
|
</ol>
|
|
<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
|
|
<a href="#t_pointer">pointer</a>
|
|
or integer <a href="#t_vector">vector</a> typed.
|
|
They must also be identical types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>icmp</tt>' compares <tt>op1</tt> and <tt>op2</tt> according to
|
|
the condition code given as <tt>cond</tt>. The comparison performed always
|
|
yields either an <a href="#t_primitive"><tt>i1</tt></a> or vector of <tt>i1</tt> result, as follows:
|
|
</p>
|
|
<ol>
|
|
<li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
|
|
<tt>false</tt> otherwise. No sign interpretation is necessary or performed.
|
|
</li>
|
|
<li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
|
|
<tt>false</tt> otherwise. No sign interpretation is necessary or performed.</li>
|
|
<li><tt>ugt</tt>: interprets the operands as unsigned values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
|
|
<li><tt>uge</tt>: interprets the operands as unsigned values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>ult</tt>: interprets the operands as unsigned values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
|
|
<li><tt>ule</tt>: interprets the operands as unsigned values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>sgt</tt>: interprets the operands as signed values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
|
|
<li><tt>sge</tt>: interprets the operands as signed values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>slt</tt>: interprets the operands as signed values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
|
|
<li><tt>sle</tt>: interprets the operands as signed values and yields
|
|
<tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
|
|
</ol>
|
|
<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
|
|
values are compared as if they were integers.</p>
|
|
<p>If the operands are integer vectors, then they are compared
|
|
element by element. The result is an <tt>i1</tt> vector with
|
|
the same number of elements as the values being compared.
|
|
Otherwise, the result is an <tt>i1</tt>.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre> <result> = icmp eq i32 4, 5 <i>; yields: result=false</i>
|
|
<result> = icmp ne float* %X, %X <i>; yields: result=false</i>
|
|
<result> = icmp ult i16 4, 5 <i>; yields: result=true</i>
|
|
<result> = icmp sgt i16 4, 5 <i>; yields: result=false</i>
|
|
<result> = icmp ule i16 -4, 5 <i>; yields: result=false</i>
|
|
<result> = icmp sge i16 4, 5 <i>; yields: result=false</i>
|
|
</pre>
|
|
|
|
<p>Note that the code generator does not yet support vector types with
|
|
the <tt>icmp</tt> instruction.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = fcmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>fcmp</tt>' instruction returns a boolean value
|
|
or vector of boolean values based on comparison
|
|
of its operands.</p>
|
|
<p>
|
|
If the operands are floating point scalars, then the result
|
|
type is a boolean (<a href="#t_primitive"><tt>i1</tt></a>).
|
|
</p>
|
|
<p>If the operands are floating point vectors, then the result type
|
|
is a vector of boolean with the same number of elements as the
|
|
operands being compared.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
|
|
the condition code indicating the kind of comparison to perform. It is not
|
|
a value, just a keyword. The possible condition code are:</p>
|
|
<ol>
|
|
<li><tt>false</tt>: no comparison, always returns false</li>
|
|
<li><tt>oeq</tt>: ordered and equal</li>
|
|
<li><tt>ogt</tt>: ordered and greater than </li>
|
|
<li><tt>oge</tt>: ordered and greater than or equal</li>
|
|
<li><tt>olt</tt>: ordered and less than </li>
|
|
<li><tt>ole</tt>: ordered and less than or equal</li>
|
|
<li><tt>one</tt>: ordered and not equal</li>
|
|
<li><tt>ord</tt>: ordered (no nans)</li>
|
|
<li><tt>ueq</tt>: unordered or equal</li>
|
|
<li><tt>ugt</tt>: unordered or greater than </li>
|
|
<li><tt>uge</tt>: unordered or greater than or equal</li>
|
|
<li><tt>ult</tt>: unordered or less than </li>
|
|
<li><tt>ule</tt>: unordered or less than or equal</li>
|
|
<li><tt>une</tt>: unordered or not equal</li>
|
|
<li><tt>uno</tt>: unordered (either nans)</li>
|
|
<li><tt>true</tt>: no comparison, always returns true</li>
|
|
</ol>
|
|
<p><i>Ordered</i> means that neither operand is a QNAN while
|
|
<i>unordered</i> means that either operand may be a QNAN.</p>
|
|
<p>Each of <tt>val1</tt> and <tt>val2</tt> arguments must be
|
|
either a <a href="#t_floating">floating point</a> type
|
|
or a <a href="#t_vector">vector</a> of floating point type.
|
|
They must have identical types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>fcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
|
|
according to the condition code given as <tt>cond</tt>.
|
|
If the operands are vectors, then the vectors are compared
|
|
element by element.
|
|
Each comparison performed
|
|
always yields an <a href="#t_primitive">i1</a> result, as follows:</p>
|
|
<ol>
|
|
<li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
|
|
<li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is equal to <tt>op2</tt>.</li>
|
|
<li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is greather than <tt>op2</tt>.</li>
|
|
<li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is less than <tt>op2</tt>.</li>
|
|
<li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
|
|
<tt>op1</tt> is not equal to <tt>op2</tt>.</li>
|
|
<li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
|
|
<li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is equal to <tt>op2</tt>.</li>
|
|
<li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is greater than <tt>op2</tt>.</li>
|
|
<li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is less than <tt>op2</tt>.</li>
|
|
<li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
|
|
<li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
|
|
<tt>op1</tt> is not equal to <tt>op2</tt>.</li>
|
|
<li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
|
|
<li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
|
|
</ol>
|
|
|
|
<h5>Example:</h5>
|
|
<pre> <result> = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
|
|
<result> = fcmp one float 4.0, 5.0 <i>; yields: result=true</i>
|
|
<result> = fcmp olt float 4.0, 5.0 <i>; yields: result=true</i>
|
|
<result> = fcmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
|
|
</pre>
|
|
|
|
<p>Note that the code generator does not yet support vector types with
|
|
the <tt>fcmp</tt> instruction.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_vicmp">'<tt>vicmp</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = vicmp <cond> <ty> <op1>, <op2> <i>; yields {ty}:result</i>
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>vicmp</tt>' instruction returns an integer vector value based on
|
|
element-wise comparison of its two integer vector operands.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>vicmp</tt>' instruction takes three operands. The first operand is
|
|
the condition code indicating the kind of comparison to perform. It is not
|
|
a value, just a keyword. The possible condition code are:</p>
|
|
<ol>
|
|
<li><tt>eq</tt>: equal</li>
|
|
<li><tt>ne</tt>: not equal </li>
|
|
<li><tt>ugt</tt>: unsigned greater than</li>
|
|
<li><tt>uge</tt>: unsigned greater or equal</li>
|
|
<li><tt>ult</tt>: unsigned less than</li>
|
|
<li><tt>ule</tt>: unsigned less or equal</li>
|
|
<li><tt>sgt</tt>: signed greater than</li>
|
|
<li><tt>sge</tt>: signed greater or equal</li>
|
|
<li><tt>slt</tt>: signed less than</li>
|
|
<li><tt>sle</tt>: signed less or equal</li>
|
|
</ol>
|
|
<p>The remaining two arguments must be <a href="#t_vector">vector</a> or
|
|
<a href="#t_integer">integer</a> typed. They must also be identical types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>vicmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
|
|
according to the condition code given as <tt>cond</tt>. The comparison yields a
|
|
<a href="#t_vector">vector</a> of <a href="#t_integer">integer</a> result, of
|
|
identical type as the values being compared. The most significant bit in each
|
|
element is 1 if the element-wise comparison evaluates to true, and is 0
|
|
otherwise. All other bits of the result are undefined. The condition codes
|
|
are evaluated identically to the <a href="#i_icmp">'<tt>icmp</tt>'
|
|
instruction</a>.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<result> = vicmp eq <2 x i32> < i32 4, i32 0>, < i32 5, i32 0> <i>; yields: result=<2 x i32> < i32 0, i32 -1 ></i>
|
|
<result> = vicmp ult <2 x i8 > < i8 1, i8 2>, < i8 2, i8 2 > <i>; yields: result=<2 x i8> < i8 -1, i8 0 ></i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_vfcmp">'<tt>vfcmp</tt>' Instruction</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> <result> = vfcmp <cond> <ty> <op1>, <op2></pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>vfcmp</tt>' instruction returns an integer vector value based on
|
|
element-wise comparison of its two floating point vector operands. The output
|
|
elements have the same width as the input elements.</p>
|
|
<h5>Arguments:</h5>
|
|
<p>The '<tt>vfcmp</tt>' instruction takes three operands. The first operand is
|
|
the condition code indicating the kind of comparison to perform. It is not
|
|
a value, just a keyword. The possible condition code are:</p>
|
|
<ol>
|
|
<li><tt>false</tt>: no comparison, always returns false</li>
|
|
<li><tt>oeq</tt>: ordered and equal</li>
|
|
<li><tt>ogt</tt>: ordered and greater than </li>
|
|
<li><tt>oge</tt>: ordered and greater than or equal</li>
|
|
<li><tt>olt</tt>: ordered and less than </li>
|
|
<li><tt>ole</tt>: ordered and less than or equal</li>
|
|
<li><tt>one</tt>: ordered and not equal</li>
|
|
<li><tt>ord</tt>: ordered (no nans)</li>
|
|
<li><tt>ueq</tt>: unordered or equal</li>
|
|
<li><tt>ugt</tt>: unordered or greater than </li>
|
|
<li><tt>uge</tt>: unordered or greater than or equal</li>
|
|
<li><tt>ult</tt>: unordered or less than </li>
|
|
<li><tt>ule</tt>: unordered or less than or equal</li>
|
|
<li><tt>une</tt>: unordered or not equal</li>
|
|
<li><tt>uno</tt>: unordered (either nans)</li>
|
|
<li><tt>true</tt>: no comparison, always returns true</li>
|
|
</ol>
|
|
<p>The remaining two arguments must be <a href="#t_vector">vector</a> of
|
|
<a href="#t_floating">floating point</a> typed. They must also be identical
|
|
types.</p>
|
|
<h5>Semantics:</h5>
|
|
<p>The '<tt>vfcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
|
|
according to the condition code given as <tt>cond</tt>. The comparison yields a
|
|
<a href="#t_vector">vector</a> of <a href="#t_integer">integer</a> result, with
|
|
an identical number of elements as the values being compared, and each element
|
|
having identical with to the width of the floating point elements. The most
|
|
significant bit in each element is 1 if the element-wise comparison evaluates to
|
|
true, and is 0 otherwise. All other bits of the result are undefined. The
|
|
condition codes are evaluated identically to the
|
|
<a href="#i_fcmp">'<tt>fcmp</tt>' instruction</a>.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
<i>; yields: result=<2 x i32> < i32 0, i32 -1 ></i>
|
|
<result> = vfcmp oeq <2 x float> < float 4, float 0 >, < float 5, float 0 >
|
|
|
|
<i>; yields: result=<2 x i64> < i64 -1, i64 0 ></i>
|
|
<result> = vfcmp ult <2 x double> < double 1, double 2 >, < double 2, double 2>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_phi">'<tt>phi</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>phi</tt>' instruction is used to implement the φ node in
|
|
the SSA graph representing the function.</p>
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The type of the incoming values is specified with the first type
|
|
field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
|
|
as arguments, with one pair for each predecessor basic block of the
|
|
current block. Only values of <a href="#t_firstclass">first class</a>
|
|
type may be used as the value arguments to the PHI node. Only labels
|
|
may be used as the label arguments.</p>
|
|
|
|
<p>There must be no non-phi instructions between the start of a basic
|
|
block and the PHI instructions: i.e. PHI instructions must be first in
|
|
a basic block.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
|
|
specified by the pair corresponding to the predecessor basic block that executed
|
|
just prior to the current block.</p>
|
|
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
Loop: ; Infinite loop that counts from 0 on up...
|
|
%indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
|
|
%nextindvar = add i32 %indvar, 1
|
|
br label %Loop
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_select">'<tt>select</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<result> = select <i>selty</i> <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
|
|
|
|
<i>selty</i> is either i1 or {<N x i1>}
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>select</tt>' instruction is used to choose one value based on a
|
|
condition, without branching.
|
|
</p>
|
|
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The '<tt>select</tt>' instruction requires an 'i1' value or
|
|
a vector of 'i1' values indicating the
|
|
condition, and two values of the same <a href="#t_firstclass">first class</a>
|
|
type. If the val1/val2 are vectors and
|
|
the condition is a scalar, then entire vectors are selected, not
|
|
individual elements.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
If the condition is an i1 and it evaluates to 1, the instruction returns the first
|
|
value argument; otherwise, it returns the second value argument.
|
|
</p>
|
|
<p>
|
|
If the condition is a vector of i1, then the value arguments must
|
|
be vectors of the same size, and the selection is done element
|
|
by element.
|
|
</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
|
|
</pre>
|
|
|
|
<p>Note that the code generator does not yet support conditions
|
|
with vector type.</p>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_call">'<tt>call</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
<result> = [tail] call [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ty> [<fnty>*] <fnptrval>(<function args>) [<a href="#fnattrs">fn attrs</a>]
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>This instruction requires several arguments:</p>
|
|
|
|
<ol>
|
|
<li>
|
|
<p>The optional "tail" marker indicates whether the callee function accesses
|
|
any allocas or varargs in the caller. If the "tail" marker is present, the
|
|
function call is eligible for tail call optimization. Note that calls may
|
|
be marked "tail" even if they do not occur before a <a
|
|
href="#i_ret"><tt>ret</tt></a> instruction.</p>
|
|
</li>
|
|
<li>
|
|
<p>The optional "cconv" marker indicates which <a href="#callingconv">calling
|
|
convention</a> the call should use. If none is specified, the call defaults
|
|
to using C calling conventions.</p>
|
|
</li>
|
|
|
|
<li>
|
|
<p>The optional <a href="#paramattrs">Parameter Attributes</a> list for
|
|
return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>',
|
|
and '<tt>inreg</tt>' attributes are valid here.</p>
|
|
</li>
|
|
|
|
<li>
|
|
<p>'<tt>ty</tt>': the type of the call instruction itself which is also
|
|
the type of the return value. Functions that return no value are marked
|
|
<tt><a href="#t_void">void</a></tt>.</p>
|
|
</li>
|
|
<li>
|
|
<p>'<tt>fnty</tt>': shall be the signature of the pointer to function
|
|
value being invoked. The argument types must match the types implied by
|
|
this signature. This type can be omitted if the function is not varargs
|
|
and if the function type does not return a pointer to a function.</p>
|
|
</li>
|
|
<li>
|
|
<p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
|
|
be invoked. In most cases, this is a direct function invocation, but
|
|
indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
|
|
to function value.</p>
|
|
</li>
|
|
<li>
|
|
<p>'<tt>function args</tt>': argument list whose types match the
|
|
function signature argument types. All arguments must be of
|
|
<a href="#t_firstclass">first class</a> type. If the function signature
|
|
indicates the function accepts a variable number of arguments, the extra
|
|
arguments can be specified.</p>
|
|
</li>
|
|
<li>
|
|
<p>The optional <a href="#fnattrs">function attributes</a> list. Only
|
|
'<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
|
|
'<tt>readnone</tt>' attributes are valid here.</p>
|
|
</li>
|
|
</ol>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>call</tt>' instruction is used to cause control flow to
|
|
transfer to a specified function, with its incoming arguments bound to
|
|
the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
|
|
instruction in the called function, control flow continues with the
|
|
instruction after the function call, and the return value of the
|
|
function is bound to the result argument.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<pre>
|
|
%retval = call i32 @test(i32 %argc)
|
|
call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
|
|
%X = tail call i32 @foo() <i>; yields i32</i>
|
|
%Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
|
|
call void %foo(i8 97 signext)
|
|
|
|
%struct.A = type { i32, i8 }
|
|
%r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
|
|
%gr = extractvalue %struct.A %r, 0 <i>; yields i32</i>
|
|
%gr1 = extractvalue %struct.A %r, 1 <i>; yields i8</i>
|
|
%Z = call void @foo() noreturn <i>; indicates that %foo never returns normally</i>
|
|
%ZZ = call zeroext i32 @bar() <i>; Return value is %zero extended</i>
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
<resultval> = va_arg <va_list*> <arglist>, <argty>
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
|
|
the "variable argument" area of a function call. It is used to implement the
|
|
<tt>va_arg</tt> macro in C.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>This instruction takes a <tt>va_list*</tt> value and the type of
|
|
the argument. It returns a value of the specified argument type and
|
|
increments the <tt>va_list</tt> to point to the next argument. The
|
|
actual type of <tt>va_list</tt> is target specific.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
|
|
type from the specified <tt>va_list</tt> and causes the
|
|
<tt>va_list</tt> to point to the next argument. For more information,
|
|
see the variable argument handling <a href="#int_varargs">Intrinsic
|
|
Functions</a>.</p>
|
|
|
|
<p>It is legal for this instruction to be called in a function which does not
|
|
take a variable number of arguments, for example, the <tt>vfprintf</tt>
|
|
function.</p>
|
|
|
|
<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
|
|
href="#intrinsics">intrinsic function</a> because it takes a type as an
|
|
argument.</p>
|
|
|
|
<h5>Example:</h5>
|
|
|
|
<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
|
|
|
|
<p>Note that the code generator does not yet fully support va_arg
|
|
on many targets. Also, it does not currently support va_arg with
|
|
aggregate types on any target.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM supports the notion of an "intrinsic function". These functions have
|
|
well known names and semantics and are required to follow certain restrictions.
|
|
Overall, these intrinsics represent an extension mechanism for the LLVM
|
|
language that does not require changing all of the transformations in LLVM when
|
|
adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
|
|
|
|
<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
|
|
prefix is reserved in LLVM for intrinsic names; thus, function names may not
|
|
begin with this prefix. Intrinsic functions must always be external functions:
|
|
you cannot define the body of intrinsic functions. Intrinsic functions may
|
|
only be used in call or invoke instructions: it is illegal to take the address
|
|
of an intrinsic function. Additionally, because intrinsic functions are part
|
|
of the LLVM language, it is required if any are added that they be documented
|
|
here.</p>
|
|
|
|
<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
|
|
a family of functions that perform the same operation but on different data
|
|
types. Because LLVM can represent over 8 million different integer types,
|
|
overloading is used commonly to allow an intrinsic function to operate on any
|
|
integer type. One or more of the argument types or the result type can be
|
|
overloaded to accept any integer type. Argument types may also be defined as
|
|
exactly matching a previous argument's type or the result type. This allows an
|
|
intrinsic function which accepts multiple arguments, but needs all of them to
|
|
be of the same type, to only be overloaded with respect to a single argument or
|
|
the result.</p>
|
|
|
|
<p>Overloaded intrinsics will have the names of its overloaded argument types
|
|
encoded into its function name, each preceded by a period. Only those types
|
|
which are overloaded result in a name suffix. Arguments whose type is matched
|
|
against another type do not. For example, the <tt>llvm.ctpop</tt> function can
|
|
take an integer of any width and returns an integer of exactly the same integer
|
|
width. This leads to a family of functions such as
|
|
<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
|
|
Only one type, the return type, is overloaded, and only one type suffix is
|
|
required. Because the argument's type is matched against the return type, it
|
|
does not require its own name suffix.</p>
|
|
|
|
<p>To learn how to add an intrinsic function, please see the
|
|
<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_varargs">Variable Argument Handling Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Variable argument support is defined in LLVM with the <a
|
|
href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
|
|
intrinsic functions. These functions are related to the similarly
|
|
named macros defined in the <tt><stdarg.h></tt> header file.</p>
|
|
|
|
<p>All of these functions operate on arguments that use a
|
|
target-specific value type "<tt>va_list</tt>". The LLVM assembly
|
|
language reference manual does not define what this type is, so all
|
|
transformations should be prepared to handle these functions regardless of
|
|
the type used.</p>
|
|
|
|
<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
|
|
instruction and the variable argument handling intrinsic functions are
|
|
used.</p>
|
|
|
|
<div class="doc_code">
|
|
<pre>
|
|
define i32 @test(i32 %X, ...) {
|
|
; Initialize variable argument processing
|
|
%ap = alloca i8*
|
|
%ap2 = bitcast i8** %ap to i8*
|
|
call void @llvm.va_start(i8* %ap2)
|
|
|
|
; Read a single integer argument
|
|
%tmp = va_arg i8** %ap, i32
|
|
|
|
; Demonstrate usage of llvm.va_copy and llvm.va_end
|
|
%aq = alloca i8*
|
|
%aq2 = bitcast i8** %aq to i8*
|
|
call void @llvm.va_copy(i8* %aq2, i8* %ap2)
|
|
call void @llvm.va_end(i8* %aq2)
|
|
|
|
; Stop processing of arguments.
|
|
call void @llvm.va_end(i8* %ap2)
|
|
ret i32 %tmp
|
|
}
|
|
|
|
declare void @llvm.va_start(i8*)
|
|
declare void @llvm.va_copy(i8*, i8*)
|
|
declare void @llvm.va_end(i8*)
|
|
</pre>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> declare void %llvm.va_start(i8* <arglist>)<br></pre>
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>llvm.va_start</tt>' intrinsic initializes
|
|
<tt>*<arglist></tt> for subsequent use by <tt><a
|
|
href="#i_va_arg">va_arg</a></tt>.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
|
|
macro available in C. In a target-dependent way, it initializes the
|
|
<tt>va_list</tt> element to which the argument points, so that the next call to
|
|
<tt>va_arg</tt> will produce the first variable argument passed to the function.
|
|
Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
|
|
last argument of the function as the compiler can figure that out.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre> declare void @llvm.va_end(i8* <arglist>)<br></pre>
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*<arglist></tt>,
|
|
which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
|
|
or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
|
|
macro available in C. In a target-dependent way, it destroys the
|
|
<tt>va_list</tt> element to which the argument points. Calls to <a
|
|
href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
|
|
<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
|
|
<tt>llvm.va_end</tt>.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
|
|
from the source argument list to the destination argument list.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
|
|
The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
|
|
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
|
|
macro available in C. In a target-dependent way, it copies the source
|
|
<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
|
|
intrinsic is necessary because the <tt><a href="#int_va_start">
|
|
llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
|
|
example, memory allocation.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_gc">Accurate Garbage Collection Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>
|
|
LLVM support for <a href="GarbageCollection.html">Accurate Garbage
|
|
Collection</a> (GC) requires the implementation and generation of these
|
|
intrinsics.
|
|
These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
|
|
stack</a>, as well as garbage collector implementations that require <a
|
|
href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
|
|
Front-ends for type-safe garbage collected languages should generate these
|
|
intrinsics to make use of the LLVM garbage collectors. For more details, see <a
|
|
href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
|
|
</p>
|
|
|
|
<p>The garbage collection intrinsics only operate on objects in the generic
|
|
address space (address space zero).</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
|
|
the code generator, and allows some metadata to be associated with it.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The first argument specifies the address of a stack object that contains the
|
|
root pointer. The second pointer (which must be either a constant or a global
|
|
value address) contains the meta-data to be associated with the root.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>At runtime, a call to this intrinsic stores a null pointer into the "ptrloc"
|
|
location. At compile-time, the code generator generates information to allow
|
|
the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
|
|
intrinsic may only be used in a function which <a href="#gc">specifies a GC
|
|
algorithm</a>.</p>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
|
|
locations, allowing garbage collector implementations that require read
|
|
barriers.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The second argument is the address to read from, which should be an address
|
|
allocated from the garbage collector. The first object is a pointer to the
|
|
start of the referenced object, if needed by the language runtime (otherwise
|
|
null).</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
|
|
instruction, but may be replaced with substantially more complex code by the
|
|
garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
|
|
may only be used in a function which <a href="#gc">specifies a GC
|
|
algorithm</a>.</p>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<pre>
|
|
declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
|
|
locations, allowing garbage collector implementations that require write
|
|
barriers (such as generational or reference counting collectors).</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The first argument is the reference to store, the second is the start of the
|
|
object to store it to, and the third is the address of the field of Obj to
|
|
store to. If the runtime does not require a pointer to the object, Obj may be
|
|
null.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
|
|
instruction, but may be replaced with substantially more complex code by the
|
|
garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
|
|
may only be used in a function which <a href="#gc">specifies a GC
|
|
algorithm</a>.</p>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_codegen">Code Generator Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
These intrinsics are provided by LLVM to expose special features that may only
|
|
be implemented with code generator support.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare i8 *@llvm.returnaddress(i32 <level>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
|
|
target-specific value indicating the return address of the current function
|
|
or one of its callers.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The argument to this intrinsic indicates which function to return the address
|
|
for. Zero indicates the calling function, one indicates its caller, etc. The
|
|
argument is <b>required</b> to be a constant integer value.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
|
|
the return address of the specified call frame, or zero if it cannot be
|
|
identified. The value returned by this intrinsic is likely to be incorrect or 0
|
|
for arguments other than zero, so it should only be used for debugging purposes.
|
|
</p>
|
|
|
|
<p>
|
|
Note that calling this intrinsic does not prevent function inlining or other
|
|
aggressive transformations, so the value returned may not be that of the obvious
|
|
source-language caller.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare i8 *@llvm.frameaddress(i32 <level>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
|
|
target-specific frame pointer value for the specified stack frame.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The argument to this intrinsic indicates which function to return the frame
|
|
pointer for. Zero indicates the calling function, one indicates its caller,
|
|
etc. The argument is <b>required</b> to be a constant integer value.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
|
|
the frame address of the specified call frame, or zero if it cannot be
|
|
identified. The value returned by this intrinsic is likely to be incorrect or 0
|
|
for arguments other than zero, so it should only be used for debugging purposes.
|
|
</p>
|
|
|
|
<p>
|
|
Note that calling this intrinsic does not prevent function inlining or other
|
|
aggressive transformations, so the value returned may not be that of the obvious
|
|
source-language caller.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare i8 *@llvm.stacksave()
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
|
|
the function stack, for use with <a href="#int_stackrestore">
|
|
<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
|
|
features like scoped automatic variable sized arrays in C99.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsic returns a opaque pointer value that can be passed to <a
|
|
href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
|
|
<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
|
|
<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
|
|
state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
|
|
practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
|
|
that were allocated after the <tt>llvm.stacksave</tt> was executed.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.stackrestore(i8 * %ptr)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
|
|
the function stack to the state it was in when the corresponding <a
|
|
href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
|
|
useful for implementing language features like scoped automatic variable sized
|
|
arrays in C99.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.prefetch(i8* <address>, i32 <rw>, i32 <locality>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
|
|
<p>
|
|
The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
|
|
a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
|
|
no
|
|
effect on the behavior of the program but can change its performance
|
|
characteristics.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
|
|
determining if the fetch should be for a read (0) or write (1), and
|
|
<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
|
|
locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
|
|
<tt>locality</tt> arguments must be constant integers.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsic does not modify the behavior of the program. In particular,
|
|
prefetches cannot trap and do not produce a value. On targets that support this
|
|
intrinsic, the prefetch can provide hints to the processor cache for better
|
|
performance.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.pcmarker(i32 <id>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
|
|
<p>
|
|
The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
|
|
(PC) in a region of
|
|
code to simulators and other tools. The method is target specific, but it is
|
|
expected that the marker will use exported symbols to transmit the PC of the
|
|
marker.
|
|
The marker makes no guarantees that it will remain with any specific instruction
|
|
after optimizations. It is possible that the presence of a marker will inhibit
|
|
optimizations. The intended use is to be inserted after optimizations to allow
|
|
correlations of simulation runs.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
<tt>id</tt> is a numerical id identifying the marker.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsic does not modify the behavior of the program. Backends that do not
|
|
support this intrinisic may ignore it.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare i64 @llvm.readcyclecounter( )
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
|
|
<p>
|
|
The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
|
|
counter register (or similar low latency, high accuracy clocks) on those targets
|
|
that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
|
|
As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
|
|
should only be used for small timings.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
When directly supported, reading the cycle counter should not modify any memory.
|
|
Implementations are allowed to either return a application specific value or a
|
|
system wide value. On backends without support, this is lowered to a constant 0.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_libc">Standard C Library Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
LLVM provides intrinsics for a few important standard C library functions.
|
|
These intrinsics allow source-language front-ends to pass information about the
|
|
alignment of the pointer arguments to the code generator, providing opportunity
|
|
for more efficient code generation.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use llvm.memcpy on any integer bit
|
|
width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare void @llvm.memcpy.i8(i8 * <dest>, i8 * <src>,
|
|
i8 <len>, i32 <align>)
|
|
declare void @llvm.memcpy.i16(i8 * <dest>, i8 * <src>,
|
|
i16 <len>, i32 <align>)
|
|
declare void @llvm.memcpy.i32(i8 * <dest>, i8 * <src>,
|
|
i32 <len>, i32 <align>)
|
|
declare void @llvm.memcpy.i64(i8 * <dest>, i8 * <src>,
|
|
i64 <len>, i32 <align>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
|
|
location to the destination location.
|
|
</p>
|
|
|
|
<p>
|
|
Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
|
|
intrinsics do not return a value, and takes an extra alignment argument.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first argument is a pointer to the destination, the second is a pointer to
|
|
the source. The third argument is an integer argument
|
|
specifying the number of bytes to copy, and the fourth argument is the alignment
|
|
of the source and destination locations.
|
|
</p>
|
|
|
|
<p>
|
|
If the call to this intrinisic has an alignment value that is not 0 or 1, then
|
|
the caller guarantees that both the source and destination pointers are aligned
|
|
to that boundary.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
|
|
location to the destination location, which are not allowed to overlap. It
|
|
copies "len" bytes of memory over. If the argument is known to be aligned to
|
|
some boundary, this can be specified as the fourth argument, otherwise it should
|
|
be set to 0 or 1.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use llvm.memmove on any integer bit
|
|
width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare void @llvm.memmove.i8(i8 * <dest>, i8 * <src>,
|
|
i8 <len>, i32 <align>)
|
|
declare void @llvm.memmove.i16(i8 * <dest>, i8 * <src>,
|
|
i16 <len>, i32 <align>)
|
|
declare void @llvm.memmove.i32(i8 * <dest>, i8 * <src>,
|
|
i32 <len>, i32 <align>)
|
|
declare void @llvm.memmove.i64(i8 * <dest>, i8 * <src>,
|
|
i64 <len>, i32 <align>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
|
|
location to the destination location. It is similar to the
|
|
'<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
|
|
</p>
|
|
|
|
<p>
|
|
Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
|
|
intrinsics do not return a value, and takes an extra alignment argument.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first argument is a pointer to the destination, the second is a pointer to
|
|
the source. The third argument is an integer argument
|
|
specifying the number of bytes to copy, and the fourth argument is the alignment
|
|
of the source and destination locations.
|
|
</p>
|
|
|
|
<p>
|
|
If the call to this intrinisic has an alignment value that is not 0 or 1, then
|
|
the caller guarantees that the source and destination pointers are aligned to
|
|
that boundary.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
|
|
location to the destination location, which may overlap. It
|
|
copies "len" bytes of memory over. If the argument is known to be aligned to
|
|
some boundary, this can be specified as the fourth argument, otherwise it should
|
|
be set to 0 or 1.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use llvm.memset on any integer bit
|
|
width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare void @llvm.memset.i8(i8 * <dest>, i8 <val>,
|
|
i8 <len>, i32 <align>)
|
|
declare void @llvm.memset.i16(i8 * <dest>, i8 <val>,
|
|
i16 <len>, i32 <align>)
|
|
declare void @llvm.memset.i32(i8 * <dest>, i8 <val>,
|
|
i32 <len>, i32 <align>)
|
|
declare void @llvm.memset.i64(i8 * <dest>, i8 <val>,
|
|
i64 <len>, i32 <align>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
|
|
byte value.
|
|
</p>
|
|
|
|
<p>
|
|
Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
|
|
does not return a value, and takes an extra alignment argument.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first argument is a pointer to the destination to fill, the second is the
|
|
byte value to fill it with, the third argument is an integer
|
|
argument specifying the number of bytes to fill, and the fourth argument is the
|
|
known alignment of destination location.
|
|
</p>
|
|
|
|
<p>
|
|
If the call to this intrinisic has an alignment value that is not 0 or 1, then
|
|
the caller guarantees that the destination pointer is aligned to that boundary.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
|
|
the
|
|
destination location. If the argument is known to be aligned to some boundary,
|
|
this can be specified as the fourth argument, otherwise it should be set to 0 or
|
|
1.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
|
|
floating point or vector of floating point type. Not all targets support all
|
|
types however.</p>
|
|
<pre>
|
|
declare float @llvm.sqrt.f32(float %Val)
|
|
declare double @llvm.sqrt.f64(double %Val)
|
|
declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
|
|
declare fp128 @llvm.sqrt.f128(fp128 %Val)
|
|
declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
|
|
returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
|
|
<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
|
|
negative numbers other than -0.0 (which allows for better optimization, because
|
|
there is no need to worry about errno being set). <tt>llvm.sqrt(-0.0)</tt> is
|
|
defined to return -0.0 like IEEE sqrt.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The argument and return value are floating point numbers of the same type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This function returns the sqrt of the specified operand if it is a nonnegative
|
|
floating point number.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
|
|
floating point or vector of floating point type. Not all targets support all
|
|
types however.</p>
|
|
<pre>
|
|
declare float @llvm.powi.f32(float %Val, i32 %power)
|
|
declare double @llvm.powi.f64(double %Val, i32 %power)
|
|
declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
|
|
declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
|
|
declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
|
|
specified (positive or negative) power. The order of evaluation of
|
|
multiplications is not defined. When a vector of floating point type is
|
|
used, the second argument remains a scalar integer value.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The second argument is an integer power, and the first is a value to raise to
|
|
that power.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This function returns the first value raised to the second power with an
|
|
unspecified sequence of rounding operations.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
|
|
floating point or vector of floating point type. Not all targets support all
|
|
types however.</p>
|
|
<pre>
|
|
declare float @llvm.sin.f32(float %Val)
|
|
declare double @llvm.sin.f64(double %Val)
|
|
declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
|
|
declare fp128 @llvm.sin.f128(fp128 %Val)
|
|
declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The argument and return value are floating point numbers of the same type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This function returns the sine of the specified operand, returning the
|
|
same values as the libm <tt>sin</tt> functions would, and handles error
|
|
conditions in the same way.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
|
|
floating point or vector of floating point type. Not all targets support all
|
|
types however.</p>
|
|
<pre>
|
|
declare float @llvm.cos.f32(float %Val)
|
|
declare double @llvm.cos.f64(double %Val)
|
|
declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
|
|
declare fp128 @llvm.cos.f128(fp128 %Val)
|
|
declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The argument and return value are floating point numbers of the same type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This function returns the cosine of the specified operand, returning the
|
|
same values as the libm <tt>cos</tt> functions would, and handles error
|
|
conditions in the same way.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
|
|
floating point or vector of floating point type. Not all targets support all
|
|
types however.</p>
|
|
<pre>
|
|
declare float @llvm.pow.f32(float %Val, float %Power)
|
|
declare double @llvm.pow.f64(double %Val, double %Power)
|
|
declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
|
|
declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
|
|
declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
|
|
specified (positive or negative) power.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The second argument is a floating point power, and the first is a value to
|
|
raise to that power.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This function returns the first value raised to the second power,
|
|
returning the
|
|
same values as the libm <tt>pow</tt> functions would, and handles error
|
|
conditions in the same way.</p>
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_manip">Bit Manipulation Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
LLVM provides intrinsics for a few important bit manipulation operations.
|
|
These allow efficient code generation for some algorithms.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic function. You can use bswap on any integer
|
|
type that is an even number of bytes (i.e. BitWidth % 16 == 0).</p>
|
|
<pre>
|
|
declare i16 @llvm.bswap.i16(i16 <id>)
|
|
declare i32 @llvm.bswap.i32(i32 <id>)
|
|
declare i64 @llvm.bswap.i64(i64 <id>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
|
|
values with an even number of bytes (positive multiple of 16 bits). These are
|
|
useful for performing operations on data that is not in the target's native
|
|
byte order.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
|
|
and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
|
|
intrinsic returns an i32 value that has the four bytes of the input i32
|
|
swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
|
|
i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
|
|
<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
|
|
additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
|
|
width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.ctpop.i8(i8 <src>)
|
|
declare i16 @llvm.ctpop.i16(i16 <src>)
|
|
declare i32 @llvm.ctpop.i32(i32 <src>)
|
|
declare i64 @llvm.ctpop.i64(i64 <src>)
|
|
declare i256 @llvm.ctpop.i256(i256 <src>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
|
|
value.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The only argument is the value to be counted. The argument may be of any
|
|
integer type. The return type must match the argument type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
|
|
integer bit width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.ctlz.i8 (i8 <src>)
|
|
declare i16 @llvm.ctlz.i16(i16 <src>)
|
|
declare i32 @llvm.ctlz.i32(i32 <src>)
|
|
declare i64 @llvm.ctlz.i64(i64 <src>)
|
|
declare i256 @llvm.ctlz.i256(i256 <src>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
|
|
leading zeros in a variable.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The only argument is the value to be counted. The argument may be of any
|
|
integer type. The return type must match the argument type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
|
|
in a variable. If the src == 0 then the result is the size in bits of the type
|
|
of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
|
|
integer bit width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.cttz.i8 (i8 <src>)
|
|
declare i16 @llvm.cttz.i16(i16 <src>)
|
|
declare i32 @llvm.cttz.i32(i32 <src>)
|
|
declare i64 @llvm.cttz.i64(i64 <src>)
|
|
declare i256 @llvm.cttz.i256(i256 <src>)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
|
|
trailing zeros.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The only argument is the value to be counted. The argument may be of any
|
|
integer type. The return type must match the argument type.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
|
|
in a variable. If the src == 0 then the result is the size in bits of the type
|
|
of src. For example, <tt>llvm.cttz(2) = 1</tt>.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
|
|
on any integer bit width.</p>
|
|
<pre>
|
|
declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
|
|
declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
|
|
range of bits from an integer value and returns them in the same bit width as
|
|
the original value.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The first argument, <tt>%val</tt> and the result may be integer types of
|
|
any bit width but they must have the same bit width. The second and third
|
|
arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
|
|
of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
|
|
<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
|
|
operates in forward mode.</p>
|
|
<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
|
|
right by <tt>%loBit</tt> bits and then ANDing it with a mask with
|
|
only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
|
|
<ol>
|
|
<li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
|
|
by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
|
|
<li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
|
|
to determine the number of bits to retain.</li>
|
|
<li>A mask of the retained bits is created by shifting a -1 value.</li>
|
|
<li>The mask is ANDed with <tt>%val</tt> to produce the result.</li>
|
|
</ol>
|
|
<p>In reverse mode, a similar computation is made except that the bits are
|
|
returned in the reverse order. So, for example, if <tt>X</tt> has the value
|
|
<tt>i16 0x0ACF (101011001111)</tt> and we apply
|
|
<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
|
|
<tt>i16 0x0026 (000000100110)</tt>.</p>
|
|
</div>
|
|
|
|
<div class="doc_subsubsection">
|
|
<a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
|
|
on any integer bit width.</p>
|
|
<pre>
|
|
declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
|
|
declare i29 @llvm.part.set.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
|
|
of bits in an integer value with another integer value. It returns the integer
|
|
with the replaced bits.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
<p>The first argument, <tt>%val</tt>, and the result may be integer types of
|
|
any bit width, but they must have the same bit width. <tt>%val</tt> is the value
|
|
whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
|
|
integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
|
|
type since they specify only a bit index.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
|
|
of operation: forwards and reverse. If <tt>%lo</tt> is greater than
|
|
<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
|
|
operates in forward mode.</p>
|
|
|
|
<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
|
|
truncating it down to the size of the replacement area or zero extending it
|
|
up to that size.</p>
|
|
|
|
<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
|
|
are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
|
|
in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
|
|
to the <tt>%hi</tt>th bit.</p>
|
|
|
|
<p>In reverse mode, a similar computation is made except that the bits are
|
|
reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
|
|
<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
|
|
<pre>
|
|
llvm.part.set(0xFFFF, 0, 4, 7) -> 0xFF0F
|
|
llvm.part.set(0xFFFF, 0, 7, 4) -> 0xFF0F
|
|
llvm.part.set(0xFFFF, 1, 7, 4) -> 0xFF8F
|
|
llvm.part.set(0xFFFF, F, 8, 3) -> 0xFFE7
|
|
llvm.part.set(0xFFFF, 0, 3, 8) -> 0xFE07
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_overflow">Arithmetic with Overflow Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
LLVM provides intrinsics for some arithmetic with overflow operations.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.sadd.with.overflow</tt>
|
|
on any integer bit width.</p>
|
|
|
|
<pre>
|
|
declare {i16, i1} @llvm.sadd.with.overflow.i16(i16 %a, i16 %b)
|
|
declare {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
|
|
declare {i64, i1} @llvm.sadd.with.overflow.i64(i64 %a, i64 %b)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed addition of the two arguments, and indicate whether an overflow
|
|
occurred during the signed summation.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The arguments (%a and %b) and the first element of the result structure may
|
|
be of integer types of any bit width, but they must have the same bit width. The
|
|
second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
|
|
and <tt>%b</tt> are the two values that will undergo signed addition.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed addition of the two variables. They return a structure — the
|
|
first element of which is the signed summation, and the second element of which
|
|
is a bit specifying if the signed summation resulted in an overflow.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%res = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
|
|
%sum = extractvalue {i32, i1} %res, 0
|
|
%obit = extractvalue {i32, i1} %res, 1
|
|
br i1 %obit, label %overflow, label %normal
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.uadd.with.overflow</tt>
|
|
on any integer bit width.</p>
|
|
|
|
<pre>
|
|
declare {i16, i1} @llvm.uadd.with.overflow.i16(i16 %a, i16 %b)
|
|
declare {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
|
|
declare {i64, i1} @llvm.uadd.with.overflow.i64(i64 %a, i64 %b)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
|
|
an unsigned addition of the two arguments, and indicate whether a carry occurred
|
|
during the unsigned summation.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The arguments (%a and %b) and the first element of the result structure may
|
|
be of integer types of any bit width, but they must have the same bit width. The
|
|
second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
|
|
and <tt>%b</tt> are the two values that will undergo unsigned addition.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
|
|
an unsigned addition of the two arguments. They return a structure — the
|
|
first element of which is the sum, and the second element of which is a bit
|
|
specifying if the unsigned summation resulted in a carry.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%res = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
|
|
%sum = extractvalue {i32, i1} %res, 0
|
|
%obit = extractvalue {i32, i1} %res, 1
|
|
br i1 %obit, label %carry, label %normal
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.ssub.with.overflow</tt>
|
|
on any integer bit width.</p>
|
|
|
|
<pre>
|
|
declare {i16, i1} @llvm.ssub.with.overflow.i16(i16 %a, i16 %b)
|
|
declare {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
|
|
declare {i64, i1} @llvm.ssub.with.overflow.i64(i64 %a, i64 %b)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed subtraction of the two arguments, and indicate whether an overflow
|
|
occurred during the signed subtraction.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The arguments (%a and %b) and the first element of the result structure may
|
|
be of integer types of any bit width, but they must have the same bit width. The
|
|
second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
|
|
and <tt>%b</tt> are the two values that will undergo signed subtraction.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed subtraction of the two arguments. They return a structure — the
|
|
first element of which is the subtraction, and the second element of which is a bit
|
|
specifying if the signed subtraction resulted in an overflow.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%res = call {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
|
|
%sum = extractvalue {i32, i1} %res, 0
|
|
%obit = extractvalue {i32, i1} %res, 1
|
|
br i1 %obit, label %overflow, label %normal
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.usub.with.overflow</tt>
|
|
on any integer bit width.</p>
|
|
|
|
<pre>
|
|
declare {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
|
|
declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
|
|
declare {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
|
|
an unsigned subtraction of the two arguments, and indicate whether an overflow
|
|
occurred during the unsigned subtraction.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The arguments (%a and %b) and the first element of the result structure may
|
|
be of integer types of any bit width, but they must have the same bit width. The
|
|
second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
|
|
and <tt>%b</tt> are the two values that will undergo unsigned subtraction.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
|
|
an unsigned subtraction of the two arguments. They return a structure — the
|
|
first element of which is the subtraction, and the second element of which is a bit
|
|
specifying if the unsigned subtraction resulted in an overflow.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%res = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
|
|
%sum = extractvalue {i32, i1} %res, 0
|
|
%obit = extractvalue {i32, i1} %res, 1
|
|
br i1 %obit, label %overflow, label %normal
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt>' Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>This is an overloaded intrinsic. You can use <tt>llvm.smul.with.overflow</tt>
|
|
on any integer bit width.</p>
|
|
|
|
<pre>
|
|
declare {i16, i1} @llvm.smul.with.overflow.i16(i16 %a, i16 %b)
|
|
declare {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
|
|
declare {i64, i1} @llvm.smul.with.overflow.i64(i64 %a, i64 %b)
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed multiplication of the two arguments, and indicate whether an overflow
|
|
occurred during the signed multiplication.</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>The arguments (%a and %b) and the first element of the result structure may
|
|
be of integer types of any bit width, but they must have the same bit width. The
|
|
second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
|
|
and <tt>%b</tt> are the two values that will undergo signed multiplication.</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
|
|
a signed multiplication of the two arguments. They return a structure —
|
|
the first element of which is the multiplication, and the second element of
|
|
which is a bit specifying if the signed multiplication resulted in an
|
|
overflow.</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%res = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
|
|
%sum = extractvalue {i32, i1} %res, 0
|
|
%obit = extractvalue {i32, i1} %res, 1
|
|
br i1 %obit, label %overflow, label %normal
|
|
</pre>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_debugger">Debugger Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
|
|
are described in the <a
|
|
href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
|
|
Debugging</a> document.
|
|
</p>
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_eh">Exception Handling Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p> The LLVM exception handling intrinsics (which all start with
|
|
<tt>llvm.eh.</tt> prefix), are described in the <a
|
|
href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
|
|
Handling</a> document. </p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_trampoline">Trampoline Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
This intrinsic makes it possible to excise one parameter, marked with
|
|
the <tt>nest</tt> attribute, from a function. The result is a callable
|
|
function pointer lacking the nest parameter - the caller does not need
|
|
to provide a value for it. Instead, the value to use is stored in
|
|
advance in a "trampoline", a block of memory usually allocated
|
|
on the stack, which also contains code to splice the nest value into the
|
|
argument list. This is used to implement the GCC nested function address
|
|
extension.
|
|
</p>
|
|
<p>
|
|
For example, if the function is
|
|
<tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
|
|
pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as follows:</p>
|
|
<pre>
|
|
%tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
|
|
%tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
|
|
%p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
|
|
%fp = bitcast i8* %p to i32 (i32, i32)*
|
|
</pre>
|
|
<p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
|
|
to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare i8* @llvm.init.trampoline(i8* <tramp>, i8* <func>, i8* <nval>)
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
This fills the memory pointed to by <tt>tramp</tt> with code
|
|
and returns a function pointer suitable for executing it.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
|
|
pointers. The <tt>tramp</tt> argument must point to a sufficiently large
|
|
and sufficiently aligned block of memory; this memory is written to by the
|
|
intrinsic. Note that the size and the alignment are target-specific - LLVM
|
|
currently provides no portable way of determining them, so a front-end that
|
|
generates this intrinsic needs to have some target-specific knowledge.
|
|
The <tt>func</tt> argument must hold a function bitcast to an <tt>i8*</tt>.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
The block of memory pointed to by <tt>tramp</tt> is filled with target
|
|
dependent code, turning it into a function. A pointer to this function is
|
|
returned, but needs to be bitcast to an
|
|
<a href="#int_trampoline">appropriate function pointer type</a>
|
|
before being called. The new function's signature is the same as that of
|
|
<tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
|
|
removed. At most one such <tt>nest</tt> argument is allowed, and it must be
|
|
of pointer type. Calling the new function is equivalent to calling
|
|
<tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
|
|
missing <tt>nest</tt> argument. If, after calling
|
|
<tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
|
|
modified, then the effect of any later call to the returned function pointer is
|
|
undefined.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p>
|
|
These intrinsic functions expand the "universal IR" of LLVM to represent
|
|
hardware constructs for atomic operations and memory synchronization. This
|
|
provides an interface to the hardware, not an interface to the programmer. It
|
|
is aimed at a low enough level to allow any programming models or APIs
|
|
(Application Programming Interfaces) which
|
|
need atomic behaviors to map cleanly onto it. It is also modeled primarily on
|
|
hardware behavior. Just as hardware provides a "universal IR" for source
|
|
languages, it also provides a starting point for developing a "universal"
|
|
atomic operation and synchronization IR.
|
|
</p>
|
|
<p>
|
|
These do <em>not</em> form an API such as high-level threading libraries,
|
|
software transaction memory systems, atomic primitives, and intrinsic
|
|
functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
|
|
application libraries. The hardware interface provided by LLVM should allow
|
|
a clean implementation of all of these APIs and parallel programming models.
|
|
No one model or paradigm should be selected above others unless the hardware
|
|
itself ubiquitously does so.
|
|
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.memory.barrier( i1 <ll>, i1 <ls>, i1 <sl>, i1 <ss>,
|
|
i1 <device> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
|
|
specific pairs of memory access types.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
|
|
The first four arguments enables a specific barrier as listed below. The fith
|
|
argument specifies that the barrier applies to io or device or uncached memory.
|
|
|
|
</p>
|
|
<ul>
|
|
<li><tt>ll</tt>: load-load barrier</li>
|
|
<li><tt>ls</tt>: load-store barrier</li>
|
|
<li><tt>sl</tt>: store-load barrier</li>
|
|
<li><tt>ss</tt>: store-store barrier</li>
|
|
<li><tt>device</tt>: barrier applies to device and uncached memory also.</li>
|
|
</ul>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This intrinsic causes the system to enforce some ordering constraints upon
|
|
the loads and stores of the program. This barrier does not indicate
|
|
<em>when</em> any events will occur, it only enforces an <em>order</em> in
|
|
which they occur. For any of the specified pairs of load and store operations
|
|
(f.ex. load-load, or store-load), all of the first operations preceding the
|
|
barrier will complete before any of the second operations succeeding the
|
|
barrier begin. Specifically the semantics for each pairing is as follows:
|
|
</p>
|
|
<ul>
|
|
<li><tt>ll</tt>: All loads before the barrier must complete before any load
|
|
after the barrier begins.</li>
|
|
|
|
<li><tt>ls</tt>: All loads before the barrier must complete before any
|
|
store after the barrier begins.</li>
|
|
<li><tt>ss</tt>: All stores before the barrier must complete before any
|
|
store after the barrier begins.</li>
|
|
<li><tt>sl</tt>: All stores before the barrier must complete before any
|
|
load after the barrier begins.</li>
|
|
</ul>
|
|
<p>
|
|
These semantics are applied with a logical "and" behavior when more than one
|
|
is enabled in a single memory barrier intrinsic.
|
|
</p>
|
|
<p>
|
|
Backends may implement stronger barriers than those requested when they do not
|
|
support as fine grained a barrier as requested. Some architectures do not
|
|
need all types of barriers and on such architectures, these become noops.
|
|
</p>
|
|
<h5>Example:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 4, %ptr
|
|
|
|
%result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
|
|
call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
|
|
<i>; guarantee the above finishes</i>
|
|
store i32 8, %ptr <i>; before this begins</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_cmp_swap">'<tt>llvm.atomic.cmp.swap.*</tt>' Intrinsic</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<p>
|
|
This is an overloaded intrinsic. You can use <tt>llvm.atomic.cmp.swap</tt> on
|
|
any integer bit width and for different address spaces. Not all targets
|
|
support all bit widths however.</p>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.cmp.swap.i8.p0i8( i8* <ptr>, i8 <cmp>, i8 <val> )
|
|
declare i16 @llvm.atomic.cmp.swap.i16.p0i16( i16* <ptr>, i16 <cmp>, i16 <val> )
|
|
declare i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* <ptr>, i32 <cmp>, i32 <val> )
|
|
declare i64 @llvm.atomic.cmp.swap.i64.p0i64( i64* <ptr>, i64 <cmp>, i64 <val> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
This loads a value in memory and compares it to a given value. If they are
|
|
equal, it stores a new value into the memory.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The <tt>llvm.atomic.cmp.swap</tt> intrinsic takes three arguments. The result as
|
|
well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
|
|
same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
|
|
this integer type. While any bit width integer may be used, targets may only
|
|
lower representations they support in hardware.
|
|
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This entire intrinsic must be executed atomically. It first loads the value
|
|
in memory pointed to by <tt>ptr</tt> and compares it with the value
|
|
<tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the memory. The
|
|
loaded value is yielded in all cases. This provides the equivalent of an
|
|
atomic compare-and-swap operation within the SSA framework.
|
|
</p>
|
|
<h5>Examples:</h5>
|
|
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 4, %ptr
|
|
|
|
%val1 = add i32 4, 4
|
|
%result1 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 4, %val1 )
|
|
<i>; yields {i32}:result1 = 4</i>
|
|
%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
|
|
|
|
%val2 = add i32 1, 1
|
|
%result2 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 5, %val2 )
|
|
<i>; yields {i32}:result2 = 8</i>
|
|
%stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
|
|
|
|
%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
|
|
<p>
|
|
This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
|
|
integer bit width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.atomic.swap.i8.p0i8( i8* <ptr>, i8 <val> )
|
|
declare i16 @llvm.atomic.swap.i16.p0i16( i16* <ptr>, i16 <val> )
|
|
declare i32 @llvm.atomic.swap.i32.p0i32( i32* <ptr>, i32 <val> )
|
|
declare i64 @llvm.atomic.swap.i64.p0i64( i64* <ptr>, i64 <val> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
|
|
the value from memory. It then stores the value in <tt>val</tt> in the memory
|
|
at <tt>ptr</tt>.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The <tt>llvm.atomic.swap</tt> intrinsic takes two arguments. Both the
|
|
<tt>val</tt> argument and the result must be integers of the same bit width.
|
|
The first argument, <tt>ptr</tt>, must be a pointer to a value of this
|
|
integer type. The targets may only lower integer representations they
|
|
support.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
|
|
stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
|
|
equivalent of an atomic swap operation within the SSA framework.
|
|
|
|
</p>
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 4, %ptr
|
|
|
|
%val1 = add i32 4, 4
|
|
%result1 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val1 )
|
|
<i>; yields {i32}:result1 = 4</i>
|
|
%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
|
|
|
|
%val2 = add i32 1, 1
|
|
%result2 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val2 )
|
|
<i>; yields {i32}:result2 = 8</i>
|
|
|
|
%stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
|
|
%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_load_add">'<tt>llvm.atomic.load.add.*</tt>' Intrinsic</a>
|
|
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<p>
|
|
This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.add</tt> on any
|
|
integer bit width. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.add.i8..p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.add.i16..p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.add.i32..p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.add.i64..p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
This intrinsic adds <tt>delta</tt> to the value stored in memory at
|
|
<tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
|
|
The intrinsic takes two arguments, the first a pointer to an integer value
|
|
and the second an integer value. The result is also an integer value. These
|
|
integer types can have any bit width, but they must all have the same bit
|
|
width. The targets may only lower integer representations they support.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This intrinsic does a series of operations atomically. It first loads the
|
|
value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
|
|
to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
|
|
</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 4, %ptr
|
|
%result1 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 4 )
|
|
<i>; yields {i32}:result1 = 4</i>
|
|
%result2 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 2 )
|
|
<i>; yields {i32}:result2 = 8</i>
|
|
%result3 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 5 )
|
|
<i>; yields {i32}:result3 = 10</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_load_sub">'<tt>llvm.atomic.load.sub.*</tt>' Intrinsic</a>
|
|
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<p>
|
|
This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.sub</tt> on
|
|
any integer bit width and for different address spaces. Not all targets
|
|
support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.sub.i8.p0i32( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.sub.i16.p0i32( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.sub.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.sub.i64.p0i32( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
This intrinsic subtracts <tt>delta</tt> to the value stored in memory at
|
|
<tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
|
|
The intrinsic takes two arguments, the first a pointer to an integer value
|
|
and the second an integer value. The result is also an integer value. These
|
|
integer types can have any bit width, but they must all have the same bit
|
|
width. The targets may only lower integer representations they support.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This intrinsic does a series of operations atomically. It first loads the
|
|
value stored at <tt>ptr</tt>. It then subtracts <tt>delta</tt>, stores the
|
|
result to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
|
|
</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 8, %ptr
|
|
%result1 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 4 )
|
|
<i>; yields {i32}:result1 = 8</i>
|
|
%result2 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 2 )
|
|
<i>; yields {i32}:result2 = 4</i>
|
|
%result3 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 5 )
|
|
<i>; yields {i32}:result3 = 2</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = -3</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_load_and">'<tt>llvm.atomic.load.and.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_nand">'<tt>llvm.atomic.load.nand.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_or">'<tt>llvm.atomic.load.or.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_xor">'<tt>llvm.atomic.load.xor.*</tt>' Intrinsic</a><br>
|
|
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<p>
|
|
These are overloaded intrinsics. You can use <tt>llvm.atomic.load_and</tt>,
|
|
<tt>llvm.atomic.load_nand</tt>, <tt>llvm.atomic.load_or</tt>, and
|
|
<tt>llvm.atomic.load_xor</tt> on any integer bit width and for different
|
|
address spaces. Not all targets support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.and.i8.p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.and.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.and.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.and.i64.p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.or.i8.p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.or.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.or.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.or.i64.p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.nand.i8.p0i32( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.nand.i16.p0i32( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.nand.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.nand.i64.p0i32( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.xor.i8.p0i32( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.xor.i16.p0i32( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.xor.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.xor.i64.p0i32( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
These intrinsics bitwise the operation (and, nand, or, xor) <tt>delta</tt> to
|
|
the value stored in memory at <tt>ptr</tt>. It yields the original value
|
|
at <tt>ptr</tt>.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
|
|
These intrinsics take two arguments, the first a pointer to an integer value
|
|
and the second an integer value. The result is also an integer value. These
|
|
integer types can have any bit width, but they must all have the same bit
|
|
width. The targets may only lower integer representations they support.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
These intrinsics does a series of operations atomically. They first load the
|
|
value stored at <tt>ptr</tt>. They then do the bitwise operation
|
|
<tt>delta</tt>, store the result to <tt>ptr</tt>. They yield the original
|
|
value stored at <tt>ptr</tt>.
|
|
</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 0x0F0F, %ptr
|
|
%result0 = call i32 @llvm.atomic.load.nand.i32.p0i32( i32* %ptr, i32 0xFF )
|
|
<i>; yields {i32}:result0 = 0x0F0F</i>
|
|
%result1 = call i32 @llvm.atomic.load.and.i32.p0i32( i32* %ptr, i32 0xFF )
|
|
<i>; yields {i32}:result1 = 0xFFFFFFF0</i>
|
|
%result2 = call i32 @llvm.atomic.load.or.i32.p0i32( i32* %ptr, i32 0F )
|
|
<i>; yields {i32}:result2 = 0xF0</i>
|
|
%result3 = call i32 @llvm.atomic.load.xor.i32.p0i32( i32* %ptr, i32 0F )
|
|
<i>; yields {i32}:result3 = FF</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = F0</i>
|
|
</pre>
|
|
</div>
|
|
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_atomic_load_max">'<tt>llvm.atomic.load.max.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_min">'<tt>llvm.atomic.load.min.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_umax">'<tt>llvm.atomic.load.umax.*</tt>' Intrinsic</a><br>
|
|
<a name="int_atomic_load_umin">'<tt>llvm.atomic.load.umin.*</tt>' Intrinsic</a><br>
|
|
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<p>
|
|
These are overloaded intrinsics. You can use <tt>llvm.atomic.load_max</tt>,
|
|
<tt>llvm.atomic.load_min</tt>, <tt>llvm.atomic.load_umax</tt>, and
|
|
<tt>llvm.atomic.load_umin</tt> on any integer bit width and for different
|
|
address spaces. Not all targets
|
|
support all bit widths however.</p>
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.max.i8.p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.max.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.max.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.max.i64.p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.min.i8.p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.min.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.min.i32..p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.min.i64..p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.umax.i8.p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.umax.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.umax.i32.p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.umax.i64.p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
|
|
<pre>
|
|
declare i8 @llvm.atomic.load.umin.i8..p0i8( i8* <ptr>, i8 <delta> )
|
|
declare i16 @llvm.atomic.load.umin.i16.p0i16( i16* <ptr>, i16 <delta> )
|
|
declare i32 @llvm.atomic.load.umin.i32..p0i32( i32* <ptr>, i32 <delta> )
|
|
declare i64 @llvm.atomic.load.umin.i64..p0i64( i64* <ptr>, i64 <delta> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
These intrinsics takes the signed or unsigned minimum or maximum of
|
|
<tt>delta</tt> and the value stored in memory at <tt>ptr</tt>. It yields the
|
|
original value at <tt>ptr</tt>.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
|
|
These intrinsics take two arguments, the first a pointer to an integer value
|
|
and the second an integer value. The result is also an integer value. These
|
|
integer types can have any bit width, but they must all have the same bit
|
|
width. The targets may only lower integer representations they support.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
These intrinsics does a series of operations atomically. They first load the
|
|
value stored at <tt>ptr</tt>. They then do the signed or unsigned min or max
|
|
<tt>delta</tt> and the value, store the result to <tt>ptr</tt>. They yield
|
|
the original value stored at <tt>ptr</tt>.
|
|
</p>
|
|
|
|
<h5>Examples:</h5>
|
|
<pre>
|
|
%ptr = malloc i32
|
|
store i32 7, %ptr
|
|
%result0 = call i32 @llvm.atomic.load.min.i32.p0i32( i32* %ptr, i32 -2 )
|
|
<i>; yields {i32}:result0 = 7</i>
|
|
%result1 = call i32 @llvm.atomic.load.max.i32.p0i32( i32* %ptr, i32 8 )
|
|
<i>; yields {i32}:result1 = -2</i>
|
|
%result2 = call i32 @llvm.atomic.load.umin.i32.p0i32( i32* %ptr, i32 10 )
|
|
<i>; yields {i32}:result2 = 8</i>
|
|
%result3 = call i32 @llvm.atomic.load.umax.i32.p0i32( i32* %ptr, i32 30 )
|
|
<i>; yields {i32}:result3 = 8</i>
|
|
%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 30</i>
|
|
</pre>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="int_general">General Intrinsics</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<p> This class of intrinsics is designed to be generic and has
|
|
no specific purpose. </p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.var.annotation(i8* <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.var.annotation</tt>' intrinsic
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first argument is a pointer to a value, the second is a pointer to a
|
|
global string, the third is a pointer to a global string which is the source
|
|
file name, and the last argument is the line number.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsic allows annotation of local variables with arbitrary strings.
|
|
This can be useful for special purpose optimizations that want to look for these
|
|
annotations. These have no other defined use, they are ignored by code
|
|
generation and optimization.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
|
|
any integer bit width.
|
|
</p>
|
|
<pre>
|
|
declare i8 @llvm.annotation.i8(i8 <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
declare i16 @llvm.annotation.i16(i16 <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
declare i32 @llvm.annotation.i32(i32 <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
declare i64 @llvm.annotation.i64(i64 <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
declare i256 @llvm.annotation.i256(i256 <val>, i8* <str>, i8* <str>, i32 <int> )
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.annotation</tt>' intrinsic.
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
The first argument is an integer value (result of some expression),
|
|
the second is a pointer to a global string, the third is a pointer to a global
|
|
string which is the source file name, and the last argument is the line number.
|
|
It returns the value of the first argument.
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsic allows annotations to be put on arbitrary expressions
|
|
with arbitrary strings. This can be useful for special purpose optimizations
|
|
that want to look for these annotations. These have no other defined use, they
|
|
are ignored by code generation and optimization.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.trap()
|
|
</pre>
|
|
|
|
<h5>Overview:</h5>
|
|
|
|
<p>
|
|
The '<tt>llvm.trap</tt>' intrinsic
|
|
</p>
|
|
|
|
<h5>Arguments:</h5>
|
|
|
|
<p>
|
|
None
|
|
</p>
|
|
|
|
<h5>Semantics:</h5>
|
|
|
|
<p>
|
|
This intrinsics is lowered to the target dependent trap instruction. If the
|
|
target does not have a trap instruction, this intrinsic will be lowered to the
|
|
call of the abort() function.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
<a name="int_stackprotector">'<tt>llvm.stackprotector</tt>' Intrinsic</a>
|
|
</div>
|
|
<div class="doc_text">
|
|
<h5>Syntax:</h5>
|
|
<pre>
|
|
declare void @llvm.stackprotector( i8* <guard>, i8** <slot> )
|
|
|
|
</pre>
|
|
<h5>Overview:</h5>
|
|
<p>
|
|
The <tt>llvm.stackprotector</tt> intrinsic takes the <tt>guard</tt> and stores
|
|
it onto the stack at <tt>slot</tt>. The stack slot is adjusted to ensure that
|
|
it is placed on the stack before local variables.
|
|
</p>
|
|
<h5>Arguments:</h5>
|
|
<p>
|
|
The <tt>llvm.stackprotector</tt> intrinsic requires two pointer arguments. The
|
|
first argument is the value loaded from the stack guard
|
|
<tt>@__stack_chk_guard</tt>. The second variable is an <tt>alloca</tt> that
|
|
has enough space to hold the value of the guard.
|
|
</p>
|
|
<h5>Semantics:</h5>
|
|
<p>
|
|
This intrinsic causes the prologue/epilogue inserter to force the position of
|
|
the <tt>AllocaInst</tt> stack slot to be before local variables on the
|
|
stack. This is to ensure that if a local variable on the stack is overwritten,
|
|
it will destroy the value of the guard. When the function exits, the guard on
|
|
the stack is checked against the original guard. If they're different, then
|
|
the program aborts by calling the <tt>__stack_chk_fail()</tt> function.
|
|
</p>
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<hr>
|
|
<address>
|
|
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
|
|
src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
|
|
<a href="http://validator.w3.org/check/referer"><img
|
|
src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
|
|
|
|
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
|
|
<a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
|
|
Last modified: $Date$
|
|
</address>
|
|
|
|
</body>
|
|
</html>
|