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597 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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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 1.1 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">
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LLVM 1.1 Release Notes
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</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="#portability">Portability and Supported Platforms</a></li>
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<li><a href="#install-instructions">Installation Instructions</a></li>
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<li><a href="#knownproblems">Known Problems</a>
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<ul>
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<!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
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<li><a href="#core">Known problems with the LLVM Core</a>
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<li><a href="#c-fe">Known problems with the C Front-end</a>
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<li><a href="#c++-fe">Known problems with the C++ Front-end</a>
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<li><a href="#x86-be">Known problems with the X86 Back-end</a>
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<li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
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<li><a href="#c-be">Known problems with the C back-end</a>
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</ul></li>
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<li><a href="#additionalinfo">Additional Information</a></li>
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</ol>
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<div class="doc_text">
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<p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><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 1.1. Here we describe the status of LLVM, including any
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known problems, and bug fixes from the previous release. The most up-to-date
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version of this document can be found on the <a
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href="http://llvm.cs.uiuc.edu/releases/1.1/">LLVM 1.1 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 potentially more
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current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
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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, that this document applies
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to the <i>next</i> release, not the previous one. To see the release notes for
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the previous release, see the <a
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href="http://llvm.cs.uiuc.edu/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 second public release of the LLVM compiler infrastructure. This
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release implements the following new features:</p>
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<ol>
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<li><a
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href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000528.html">A new
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LLVM profiler, similar to gprof</a> is available</li>
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<li>LLVM and the C/C++ front-end now compile on Mac OSX! Mac OSX users can
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now explore the LLVM optimizer with the C backend (note that LLVM requires GCC
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3.3 on Mac OSX).</li>
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<li>LLVM has been <a
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href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000554.html">moved
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into an 'llvm' C++ namespace</a>, for easier integration with third-party
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code. Note that due to a bug in GDB 5.x, to debug namespacified LLVM code,
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you will need to upgrade to GDB 6.</li>
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</ol>
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<p>In this release, the following missing features were implemented:</p>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR88">The interpreter does not support
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invoke or unwind</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR99">Interpreter does not support the
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<tt>vaarg</tt> instruction</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR117">llvm-nm cannot read archive
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files</a></li>
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</ol>
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<p>In this release, the following Quality of Implementation issues were
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fixed:</p>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR29">C++ front-end is not generating
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linkonce linkage type when it can</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR84">C front-end doesn't emit
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getelementptr for address of array element</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR96">Bad path to the C/C++ frontend causes
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build problems</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR114">LLVM header files should be -Wold-style-cast clean</a></li>
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<li>The LLVM bytecode reader has been <a
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href="http://llvm.cs.uiuc.edu/PR127">sped up a lot</a> (up to 4x in some
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cases).</li>
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<li>Methods and functions in anonymous namespaces <a href="http://llvm.cs.uiuc.edu/PR85">now get internal linkage</a>.</li>
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</ol>
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<p>In this release, the following bugs in the previous release were fixed:</p>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR57">[inliner] Inlining invoke with PHI in unwind target is broken</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR58">[linker] linkonce globals should link successfully to external globals</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR59">C++ frontend can crash when compiling virtual base classes</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR62">C backend fails on constant cast expr to ptr-to-anonymous struct</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR63">#ident is not recognized by C frontend</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR64">[constmerge] Constant merging pass merges constants with external linkage</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR65">C front-end miscompiles the builtin_expect intrinsic!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR66">[scalarrepl] Scalar Replacement of aggregates is decimating structures it shouldn't be</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR67">1.0 precompiled libstdc++ does not include wchar_t support</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR68">llvmgcc asserts when compiling functions renamed with asm's</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR69">C frontend crashes on some programs with lots of types.</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR70">[instcombine] Resolving invoke inserts cast after terminator</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR71">llvm-as crashes when labels are used in phi nodes</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR72">[build problem] Callgraph.cpp not pulled in from libipa.a</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR77">Variables in scope of output setjmp
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calls should be volatile</a>. Note that this does not effect correctness on
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many platforms, such as X86.</li>
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<li><a href="http://llvm.cs.uiuc.edu/PR79">llvm-gcc crashes compiling global union initializer</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR80">C front-end crash on empty structure</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR81">CFrontend crashes when compiling C99 compound expressions</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR83">[X86] Emission of global bool initializers broken</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR87">llvm-gcc infinite loops on "case MAXINT:"</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR89">[C++] Catch blocks make unparsable labels</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR90">[C++] Initializing array with constructable objects fail</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR91">[gccld] The -r (relinking) option does not work correctly</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR92">[bcreader] Cannot read shift constant expressions from bytecode file</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR93">[lowersetjmp] Lowersetjmp pass breaks dominance properties!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR94">llvm-gcc tries to add bools</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR95">SymbolTable::getUniqueName is very inefficient</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR98">[buildscripts] Building into objdir with .o in it fails</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR101">[setjmp/longjmp] Linking C programs which use setjmp/longjmp sometimes fail with references to the C++ runtime library!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR104">[c++] C++ Frontend lays out superclasses like anonymous bitfields!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR107">AsmParser Misses Symbol Redefinition Error</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR108">gccld -Lfoo -lfoo fails to find ./foo/libfoo.a</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR110">[bcreader] Incorrect cast causes misread forward constant references</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR112">Casting a string constant to void crashes llvm-gcc</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR116">[adce] ADCE considers blocks without postdominators to be unreachable</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR54">C front-end miscompiles unsigned enums whose LLVM types are signed</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR123">[X86] div and rem constant exprs invalidate iterators!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR125">[llvmg++] Enum types are incorrectly shrunk to smaller than 'int' size</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR128">[llvmg++] Cannot use pointer to member to initialize global</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR130">[vmcore] Symbol table doesn't rename colliding variables during type resolution</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR131">[llvm-gcc] ?: operator as lvalue not implemented</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR133">[C/C++] Bogus warning about taking the address of 'register' variable</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR97">bugpoint must not pass -R<directory> to Mach-O linker</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR113">crash assigning into an array in a struct which contains a bitfield</a>.</li>
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<li><a href="http://llvm.cs.uiuc.edu/PR6">Oversized integer bitfields cause crash</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR140">gccld produces a runner script that includes command-line options to load the necessary shared objects</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR141">[llvm-gcc] Bitfields & large array don't mix well</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR132">[llvm-gcc] Complex division is not supported</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR143">[llvm-gcc] Illegal union field reference</a></li>
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</ol><p>
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<p>At this time, LLVM is known to work properly with SPEC CPU 2000 (X86 only),
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the Olden benchmarks, and the Ptrdist benchmarks among many other programs.
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Note however that the Sparc and X86 backends do not currently support exception
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throwing or long jumping (including 253.perlbmk in SPEC). For these programs,
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you must use the C backend.</p>
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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 has been extensively tested on Intel and AMD machines running Red
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Hat Linux, and Sun UltraSPARC workstations running Solaris 8. Additionally,
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LLVM works on Mac OS/X 10.3 and above, but only with the C back-end (no native
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backend for the PowerPC is available yet).
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The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
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work on more platforms than that. However, it is likely that we
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missed something, and that minor porting is required to get LLVM to work on
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new platforms. We welcome portability patches and 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.</p>
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</div>
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<!-- _______________________________________________________________________ -->
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<!--
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</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
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-->
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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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<li>The JIT does not use mutexes to protect its internal data structures. As
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such, execution of a threaded program could cause these data structures to be
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corrupted.</li>
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<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
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<li>Linking in static archive files (.a files) is very slow (there is no symbol
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table in the archive).</li>
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<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
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more than 256 elements</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="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">
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Bugs
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</div>
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<div class="doc_text">
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<ul>
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<li>C99 Variable sized arrays do not release stack memory when they go out of
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scope. Thus, the following program may run out of stack space:
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<pre>
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for (i = 0; i != 1000000; ++i) {
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int X[n];
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foo(X);
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}
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</pre></li>
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</ul>
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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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<li>Inline assembly is not yet supported.</li>
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<li>"long double" is transformed by the front-end into "double". There is no
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support for floating point data types of any size other than 32 and 64
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bits.</li>
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<li>The following Unix system functionality has not been tested and may not
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work:
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<ol>
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<li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
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appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
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<tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
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<li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
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- These functions have not been tested.
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</ol></li>
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<li>Although many GCC extensions are supported, some are not. In particular,
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the following extensions are known to <b>not be</b> supported:
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<ol>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
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<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>
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<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>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
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<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>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands</li>
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<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>
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<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>
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<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>
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<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>
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<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>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
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</ol>
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<p>The following GCC extensions are <b>partially</b> supported. An ignored
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attribute means that the LLVM compiler ignores the presence of the attribute,
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but the code should still work. An unsupported attribute is one which is
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ignored by the LLVM compiler, which will cause a different interpretation of
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the program.</p>
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<ol>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
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Arrays whose length is computed at run time.<br>
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Supported, but allocated stack space is not freed until the function returns (noted above).</li>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
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Declaring that functions have no side effects, or that they can never
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return.<br>
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<b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
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<tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
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<tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
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<b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
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<tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
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<tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
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<b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
|
|
<tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
|
|
<tt>fastcall</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>transparent_union</tt>,
|
|
<tt>unused</tt>, <tt>weak</tt><br>
|
|
|
|
<b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
|
|
<tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
|
|
<tt>vector_size</tt>, <tt>dllimport</tt>,
|
|
<tt>dllexport</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.
|
|
<b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
|
|
<tt>deprecated</tt>, <tt>may_alias</tt>
|
|
|
|
<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> (ignored).</li>
|
|
|
|
</ol>
|
|
|
|
<p>The following extensions <b>are</b> known to be supported:</p>
|
|
|
|
<ol>
|
|
<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/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/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---Comments.html#C++%20Comments">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/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 functional but
|
|
of <b>beta</b> quality. It has been tested and works for a number of simple
|
|
programs that collectively exercise most of the language. Nevertheless, it has
|
|
not been in use as long as the C front-end. Please report any bugs or
|
|
problems.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
Bugs
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
|
|
front-end</a></li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
Notes
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
|
|
parser is significantly more standards compliant (and picky) than prior GCC
|
|
versions. For more information, see the C++ section of the <a
|
|
href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
|
|
|
|
<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 is very
|
|
different from the model used in the Itanium ABI, so <b>exceptions will not
|
|
interact correctly</b>. </li>
|
|
|
|
<li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing destructors when
|
|
unwinding is not shared</a> (this is a quality of implementation problem,
|
|
which does not effect functionality).</li>
|
|
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="x86-be">Known problems with the X86 back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>The X86 code generator <a
|
|
href="http://llvm.cs.uiuc.edu/PR16">does not currently
|
|
support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
|
|
or calls the C <tt>longjmp</tt> function will abort.</li>
|
|
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="sparc-be">Known problems with the Sparc back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>The Sparc code generator <a
|
|
href="http://llvm.cs.uiuc.edu/PR15">does not currently
|
|
support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
|
|
or calls the C <tt>longjmp</tt> function will abort.</li>
|
|
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c-be">Known problems with the C back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>The C back-end produces code that violates the ANSI C Type-Based Alias
|
|
Analysis rules. As such, special options may be necessary to compile the code
|
|
(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
|
|
problem probably cannot be fixed.</li>
|
|
|
|
<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
|
|
cannot include special floating point numbers like Not-A-Number or
|
|
Infinity.</li>
|
|
|
|
<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
|
|
supported</a>. This should not affect LLVM produced by the C or C++
|
|
frontends.</li>
|
|
|
|
<li>The code produces by the C back-end has only been tested with the Sun CC,
|
|
GCC, and Intel compilers. It is possible that it will have to be adjusted to
|
|
support other C compilers.</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 LLVM web page,
|
|
including mailing lists publications describing algorithms and components
|
|
implemented in LLVM. 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 mailing lists.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
<hr>
|
|
<address>
|
|
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src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
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<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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