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- Document visibility stuff - Fix gcc' supported attributes list - Document udis86 configure option git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33462 91177308-0d34-0410-b5e6-96231b3b80d8
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688 lines
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<!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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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 1.9 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">LLVM 1.9 Release Notes</div>
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<ol>
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<li><a href="#intro">Introduction</a></li>
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<li><a href="#whatsnew">What's New?</a></li>
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<li><a href="GettingStarted.html">Installation Instructions</a></li>
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<li><a href="#portability">Portability and Supported Platforms</a></li>
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<li><a href="#knownproblems">Known Problems</a>
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<li><a href="#additionalinfo">Additional Information</a></li>
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</ol>
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<div class="doc_author">
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<p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="intro">Introduction</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This document contains the release notes for the LLVM compiler
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infrastructure, release 1.9. Here we describe the status of LLVM, including any
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known problems and major improvements from the previous release. The most
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up-to-date version of this document (corresponding to LLVM CVS) can be found
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on the <a
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href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
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not reading this on the LLVM web pages, you should probably go there because
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this document may be updated after the release.</p>
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<p>For more information about LLVM, including information about the latest
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release, please check out the <a href="http://llvm.org/">main LLVM
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web site</a>. If you have questions or comments, the <a
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href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
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list</a> is a good place to send them.</p>
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<p>Note that if you are reading this file from CVS or the main LLVM web page,
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this document applies to the <i>next</i> release, not the current one. To see
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the release notes for the current or previous releases, see the <a
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href="http://llvm.org/releases/">releases page</a>.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="whatsnew">What's New?</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This is the tenth public release of the LLVM Compiler Infrastructure. This
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release incorporates a large number of enhancements, new features, and bug
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fixes. We recommend that all users of previous LLVM versions upgrade.
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</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="newfeatures">New Features in LLVM 1.9</a>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="x86-64">New X86-64 Backend</a></div>
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<div class="doc_text">
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<p>LLVM 1.9 now fully supports the x86-64 instruction set on Mac OS/X, and
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supports it on Linux (and other operating systems) when compiling in -static
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mode. LLVM includes JIT support for X86-64, and supports both Intel EMT-64T
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and AMD-64 architectures. The X86-64 instruction set permits addressing a
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64-bit addressing space and provides the compiler with twice the
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number of integer registers to use.</p>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="lto">Link-Time Optimization integration
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with native linkers</a></div>
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<div class="doc_text">
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<p>LLVM now includes <a href="LinkTimeOptimization.html">liblto</a> which can
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be used to integrate LLVM Link-Time Optimization support into a native linker.
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This allows LLVM .bc to transparently participate with linking an application,
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even when some .o files are in LLVM form and some are not.</p>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="dwarf">DWARF debugging
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support for Linux, Cygwin and MinGW on X86</a></div>
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<div class="doc_text">
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<p>llvm-gcc4 now supports generating debugging info for Linux, Cygwin and MinGW.
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This extends the PPC/Darwin and X86/Darwin debugging support available in the
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1.8 release. DWARF is a standard debugging format used on many platforms.</p>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="optimizer">Optimizer
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Improvements</a></div>
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<div class="doc_text">
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<p>The mid-level optimizer is now faster and produces better code in many cases.
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Significant changes include:</p>
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<ul>
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<li>LLVM includes a new 'predicate simplifier' pass, which
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currently performs dominator tree-based optimizations.</li>
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<li>The complete loop unroll pass now supports unrolling of
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multiple basic block loops.</li>
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<li>The 'globalopt' pass can now perform the scalar replacement of
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aggregates transformation on some heap allocations.</li>
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<li>The globalsmodref-aa alias analysis can now track 'indirect pointer
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globals' more accurately.</li>
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<li>The instruction combiner can now perform element propagation
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analysis of vector expressions, eliminating computation of vector elements
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that are not used.</li>
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</ul>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="codegen">Code
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Generator Enhancements</a></div>
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<div class="doc_text">
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<p>
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The LLVM Target-Independent code generator now supports more target features and
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optimizes many cases more aggressively. New features include:
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</p>
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<ul>
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<li>LLVM now includes a late branch folding pass which optimizes code
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layout, performs several branch optzns, and deletes unreachable code.</li>
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<li>The code generator now support targets that have pre/post-increment
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addressing modes.</li>
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<li>LLVM now supports dynamically-loadable register allocators and
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schedulers.</li>
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<li>LLVM 1.9 includes several improvements to inline asm support,
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including support for new constraints and modifiers.</li>
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<li>The register coalescer is now more aggressive than before,
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allowing it to eliminate more copies.</li>
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</ul>
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<p>In addition, the LLVM target description format has itself been extended in
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several ways:</p>
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<ul>
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<li>tblgen now allows definition of '<a
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href="TableGenFundamentals.html#multiclass">multiclasses</a>' which can be
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used to factor instruction patterns more aggressively in .td files.</li>
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<li>LLVM has a new TargetAsmInfo class which captures a variety of
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information about the target assembly language format.</li>
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<li>.td files now support "<tt>${:foo}</tt>" syntax for encoding
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subtarget-specific assembler syntax into instruction descriptions.</li>
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</ul>
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<p>Further, several significant target-specific enhancements are included in
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LLVM 1.9:</p>
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<ul>
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<li>The LLVM ARM backend now supports more instructions
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and the use of a frame pointer. It is now possible to build
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libgcc and a simple cross compiler, but it is not considered "complete" yet.
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</li>
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<li>LLVM supports the Win32 dllimport/dllexport linkage and
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stdcall/fastcall calling conventions.</li>
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</ul>
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</div>
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<!--_________________________________________________________________________-->
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<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
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<div class="doc_text">
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<p>This release includes many other improvements, including improvements to
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the optimizers and code generators (improving the generated code) changes to
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speed up the compiler in many ways (improving algorithms and fine tuning
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code), and changes to reduce the code size of the compiler itself.</p>
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<p>More specific changes include:</p>
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<ul>
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<li>The llvm-test framework now supports SPEC2006.</li>
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<li>LLVM now includes a <a href="GetElementPtr.html">FAQ about the
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<tt>getelementptr</tt> instruction</a>.</li>
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<li>Bugpoint now supports a new "<tt>-find-bugs</tt>" mode. This mode makes
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bugpoint permute pass sequences to try to expose bugs due to pass
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sequencing.</li>
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<li>The JIT now supports lazily streaming code from multiple modules at a
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time, implicitly linking the code as it goes.</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="apichanges">Significant API Changes in LLVM 1.9</a>
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</div>
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<div class="doc_text">
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<p>Several significant API changes have been made. If you are maintaining
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out-of-tree code, please be aware that:</p>
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<ul>
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<li>The ConstantSInt and ConstantUInt classes have been merged into the
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ConstantInt class.</li>
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<li><p>As a step towards making LLVM's integer types signless, several new
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instructions have been added to LLVM. The <tt>Div</tt> instruction is now
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<tt>UDiv</tt>, <tt>SDiv</tt>, and <tt>FDiv</tt>. The <tt>Rem</tt> instruction
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is now <tt>URem</tt>, <tt>SRem</tt> and <tt>FRem</tt>. See the
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<a href="LangRef.html">Language Reference</a> for details on these new
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instructions.</p>
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<li><p><tt>ConstantBool::True</tt> and <tt>ConstantBool::False</tt> have been
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renamed to <tt>ConstantBool::getTrue()</tt> and
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<tt>ConstantBool::getFalse()</tt>.</p></li>
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<li>The 'analyze' tool has been merged into the 'opt' tool.</li>
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</ul>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="portability">Portability and Supported Platforms</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>LLVM is known to work on the following platforms:</p>
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<ul>
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<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
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(and probably other unix-like systems).</li>
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<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
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<li>Sun UltraSPARC workstations running Solaris 8.</li>
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<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
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support is available for native builds with Visual C++).</li>
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<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
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64-bit modes.</li>
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<li>Alpha-based machines running Debian GNU/Linux.</li>
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<li>Itanium-based machines running Linux and HP-UX.</li>
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</ul>
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<p>The core LLVM infrastructure uses
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<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
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to the machine and operating system on which it is built. However, minor
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porting may be required to get LLVM to work on new platforms. We welcome your
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portability patches and reports of successful builds or error messages.</p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="knownproblems">Known Problems</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This section contains all known problems with the LLVM system, listed by
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component. As new problems are discovered, they will be added to these
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sections. If you run into a problem, please check the <a
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href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
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there isn't already one.</p>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="experimental">Experimental features included with this release</a>
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</div>
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<div class="doc_text">
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<p>The following components of this LLVM release are either untested, known to
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be broken or unreliable, or are in early development. These components should
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not be relied on, and bugs should not be filed against them, but they may be
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useful to some people. In particular, if you would like to work on one of these
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components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
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<ul>
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<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
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future release.</li>
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<li>The IA64 code generator is experimental.</li>
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<li>The ARM code generator is experimental.</li>
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<li>The Alpha JIT is experimental.</li>
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<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
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<tt>-filetype</tt> llc option.</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="x86-be">Known problems with the X86 back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
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assembly that uses the X86 floating point stack</a>. See the <a
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href="http://llvm.org/PR879">bug</a> for details on workarounds on
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Linux.</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="ppc-be">Known problems with the PowerPC back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
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implement ordered FP comparisons</a>.</li>
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<li>The 64-bit PowerPC backend is not fully stable. If you desire PPC64 support,
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please use mainline CVS LLVM, which has several important bug fixes.</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="sparc-be">Known problems with the SPARC back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
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support the 64-bit SPARC ABI (-m64).</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="c-be">Known problems with the C back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>The C back-end produces code that violates the ANSI C Type-Based Alias
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Analysis rules. As such, special options may be necessary to compile the code
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(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
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problem probably cannot be fixed.</li>
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<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
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supported</a>. This should not affect LLVM produced by the C or C++
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frontends.</li>
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<li>The C backend does not correctly implement the <a
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href="LangRef.html#i_stacksave"><tt>llvm.stacksave</tt></a> or
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<a href="LangRef.html#i_stackrestore"><tt>llvm.stackrestore</tt></a>
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intrinsics. This means that some code compiled by it can run out of stack
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space if they depend on these (e.g. C99 varargs).</li>
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<li><a href="http://llvm.org/PR802">The C backend does not support inline
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assembly code</a>.</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="alpha-be">Known problems with the Alpha back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
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appropriate nops inserted to ensure restartability.</li>
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</ul>
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</div>
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|
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="ia64-be">Known problems with the IA64 back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
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made where the argument is not 16-byte aligned, as required on IA64. (Strictly
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speaking this is not a bug in the IA64 back-end; it will also be encountered
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when building C++ programs using the C back-end.)</li>
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<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
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ABI compliant layout of v-tables</a>. In particular, it just stores function
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pointers instead of function descriptors in the vtable. This bug prevents
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mixing C++ code compiled with LLVM with C++ objects compiled by other C++
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compilers.</li>
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<li>There are a few ABI violations which will lead to problems when mixing LLVM
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output with code built with other compilers, particularly for floating-point
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programs.</li>
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<li>Defining vararg functions is not supported (but calling them is ok).</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="arm-be">Known problems with the ARM back-end</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>The ARM backend is currently in early development stages, it is not
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ready for production use.</li>
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</ul>
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</div>
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="core">Known problems with the LLVM Core</a>
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</div>
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<div class="doc_text">
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<ul>
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<li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
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work.</li>
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</ul>
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</div>
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|
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="c-fe">Known problems with the C front-end</a>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection">Bugs</div>
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<div class="doc_text">
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<p>
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<p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
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does not currently support <a href="http://llvm.org/PR869">Link-Time
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Optimization</a> or <a href="http://llvm.org/PR870">C++ Exception Handling</a>,
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which llvm-gcc3 does.</p>
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<p>llvm-gcc4 does not support the <a href="http://llvm.org/PR947">GCC indirect
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goto extension</a>, but llvm-gcc3 does.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection">
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Notes
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</div>
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<div class="doc_text">
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<ul>
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|
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<li>"long double" is transformed by the front-end into "double". There is no
|
|
support for floating point data types of any size other than 32 and 64
|
|
bits.</li>
|
|
|
|
<li>Although many GCC extensions are supported, some are not. In particular,
|
|
the following extensions are known to <b>not be</b> supported:
|
|
<ol>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
|
|
</ol>
|
|
|
|
<p>The following GCC extensions are <b>partially</b> supported. An ignored
|
|
attribute means that the LLVM compiler ignores the presence of the attribute,
|
|
but the code should still work. An unsupported attribute is one which is
|
|
ignored by the LLVM compiler and will cause a different interpretation of
|
|
the program.</p>
|
|
|
|
<ol>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
|
|
Arrays whose length is computed at run time.<br>
|
|
Supported, but allocated stack space is not freed until the function returns (noted above).</li>
|
|
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
|
|
|
|
Declaring that functions have no side effects or that they can never
|
|
return.<br>
|
|
|
|
<b>Supported:</b> <tt>constructor</tt>, <tt>destructor</tt>,
|
|
<tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
|
|
<tt>format_arg</tt>, <tt>non_null</tt>, <tt>noreturn</tt>,
|
|
<tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
|
|
<tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
|
|
|
|
<b>Ignored:</b> <tt>noinline</tt>,
|
|
<tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
|
|
<tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
|
|
|
|
<b>Unsupported:</b> <tt>alias</tt>, <tt>regparm</tt>, all other target specific
|
|
attributes</li>
|
|
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
|
|
Specifying attributes of variables.<br>
|
|
<b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
|
|
<tt>deprecated</tt>, <tt>dllimport</tt>, <tt>dllexport</tt>,
|
|
<tt>section</tt>, <tt>transparent_union</tt>, <tt>unused</tt>,
|
|
<tt>used</tt>, <tt>weak</tt><br>
|
|
|
|
<b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
|
|
<tt>shared</tt>, <tt>tls_model</tt>,
|
|
<tt>vector_size</tt>, all target specific attributes.
|
|
</li>
|
|
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
|
|
<b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
|
|
<tt>deprecated</tt>, <tt>may_alias</tt><br>
|
|
|
|
<b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
|
|
all target specific attributes.</li>
|
|
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
|
|
Other built-in functions.<br>
|
|
We support all builtins which have a C language equivalent (e.g.,
|
|
<tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
|
|
<tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
|
|
<tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
|
|
(currently ignored). We also support builtins for ISO C99 floating
|
|
point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
|
|
<tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
|
|
<tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
|
|
</ol>
|
|
|
|
<p>The following extensions <b>are</b> known to be supported:</p>
|
|
|
|
<ol>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
|
|
or arrays as values.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character <ESC>.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
|
|
</ol></li>
|
|
|
|
</ul>
|
|
|
|
<p>If you run into GCC extensions which have not been included in any of these
|
|
lists, please let us know (also including whether or not they work).</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c++-fe">Known problems with the C++ front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>For this release, the C++ front-end is considered to be fully
|
|
tested and works for a number of non-trivial programs, including LLVM
|
|
itself.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
Notes
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<ul>
|
|
<li>llvm-gcc4 does not support C++ exception handling at all yet.</li>
|
|
|
|
<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
|
|
performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
|
|
function and in the <tt>setjmp</tt> receiver function may not be run.
|
|
Objects in intervening stack frames will be destroyed, however (which is
|
|
better than most compilers).</li>
|
|
|
|
<li>The LLVM C++ front-end follows the <a
|
|
href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
|
|
This document, which is not Itanium specific, specifies a standard for name
|
|
mangling, class layout, v-table layout, RTTI formats, and other C++
|
|
representation issues. Because we use this API, code generated by the LLVM
|
|
compilers should be binary compatible with machine code generated by other
|
|
Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
|
|
<i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
|
|
different from the model used in the Itanium ABI, so <b>exceptions will not
|
|
interact correctly</b>. </li>
|
|
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="additionalinfo">Additional Information</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>A wide variety of additional information is available on the <a
|
|
href="http://llvm.org">LLVM web page</a>, including <a
|
|
href="http://llvm.org/docs/">documentation</a> and <a
|
|
href="http://llvm.org/pubs/">publications describing algorithms and
|
|
components implemented in LLVM</a>. The web page also contains versions of the
|
|
API documentation which is up-to-date with the CVS version of the source code.
|
|
You can access versions of these documents specific to this release by going
|
|
into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
|
|
|
|
<p>If you have any questions or comments about LLVM, please feel free to contact
|
|
us via the <a href="http://llvm.org/docs/#maillist"> mailing
|
|
lists</a>.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
<hr>
|
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<a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
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