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625 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 1.2 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 1.2 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="#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 the <a href="http://llvm.cs.uiuc.edu">LLVM team</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 1.2. 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/1.2/">LLVM 1.2 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, this document applies
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to the <i>next</i> release, not the current one. To see the release notes for
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the current or previous releases, 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 third public release of the LLVM compiler infrastructure.
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</p>
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<p>At this time, LLVM is known to correctly compile and run all non-unwinding C
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& C++ SPEC CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist
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benchmarks. It has also been used to compile <b>many</b> other programs. LLVM
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now also works with a broad variety of C++ programs, though it has still
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received much less testing than the C front-end.
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</p>
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<p>
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The LLVM native code generators are very stable but do not currently support
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unwinding (exception throwing or <tt>longjmp</tt>ing), which prevent them from
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working with programs like the <tt>253.perlbmk</tt> in SPEC CPU2000. The C
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backend and the rest of LLVM supports these programs, so you can
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still use LLVM with them. Support for unwinding will be added in a future
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release.
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</p>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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This release implements the following new features:
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</div>
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<ol>
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<li></li>
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<li></li>
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</ol>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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In this release, the following missing features were implemented:
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</div>
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<ol>
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<li></li>
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<li></li>
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</ol>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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In this release, the following Quality of Implementation issues were fixed:
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</div>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR135">JIT should lazily initialize global variables</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR192">[X86] X86 Backend never releases memory for machine code structures</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR196">[vmcore] OpaqueType objects memory leak</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR182">[llvmgcc] C front-end does not compile "extern inline" into linkonce</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR73">Bytecode format inconsistent</a></li>
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</ol>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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In this release, the following build problems were fixed:
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</div>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR210">[build] Makefiles break if C frontend target string has unexpected value</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR214">[build] hard-wired assumption that shared-library extension is ".so"</a></li>
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<li><A href="http://llvm.cs.uiuc.edu/PR222">make tools-only doesn't make lib/Support</a></li>
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</ol>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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In this release, the following Code Quality issues were fixed:
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</div>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR187">[loopsimplify] Many pointless phi nodes are created</a></li>
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<li>The X86 backend didn't generate <tt>fchs</tt> to negate floating point numbers</li>
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</ol>
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<!--=========================================================================-->
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<div class="doc_subsubsection">
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In this release, the following bugs in the previous release were fixed:
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</div>
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<p>Bugs in the LLVM Core:</p>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR179">[licm] LICM promotes volatile memory
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locations to registers</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR191">[licm] Memory read after free causes
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infrequent crash</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR194">[indvars] Induction variable
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canonicalization always makes 32-bit indvars</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR193">[constantmerge] Merging globals can
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cause use of invalid pointers!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR212">[bcreader] Bytecode reader misreads 'long -9223372036854775808'!</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR218">VMCore mishandles double -0.0</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR219">[X86] X86 backend code generates -0.0 as +0.0</a></li>
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</ol>
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<p>Bugs in the C/C++ front-end:</p>
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<ol>
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<li><a href="http://llvm.cs.uiuc.edu/PR186">Need weak linkage on memory
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management functions in libc runtime to allow them to be overriden</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR202">[llvm-gcc] asserts when an extern inline function is redefined</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR204">[llvmg++] Dynamically initialized constants cannot be marked 'constant'</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR216">[llvmgcc] floating-point unary minus is incorrect for +0.0</a></li>
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<li><a href="http://llvm.cs.uiuc.edu/PR221">[llvm-gcc] miscompilation of 'X = Y = Z' with aggregate values</a></li>
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</ol>
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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 FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
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Additionally,
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LLVM works on Mac OS X 10.3 and above, but only with the C backend or
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interpreter (no native 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. If you run into a problem, please check the <a
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href="http://llvm.cs.uiuc.edu/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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<!--
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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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<li>
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The gccld program
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<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=139">
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does not link objects/archives in the order specified on the command line.
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</a>
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</li>
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<li>
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<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=174">
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Tail duplication does not update SSA form correctly.
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</a>
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</li>
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<li><a href="http://llvm.cs.uiuc.edu/PR16">[lowerinvoke] The -lowerinvoke pass
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does not insert calls to setjmp/longjmp</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">Bugs</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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<li>
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Initialization of global union variables can only be done
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<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
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union member</a>.
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</li>
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<li>
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<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=182">
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Functions marked "extern inline" are not compiled into LLVM with linkonce
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linkage.
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</a>
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</li>
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<li>
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The memory management functions in the libc runtime
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<a href="http://llvm.cs.uiuc.edu/PR186">need weak linkage so that they can be
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overridden.
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</a>
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</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 and 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>,
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<tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
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<tt>fastcall</tt>, all other target specific attributes</li>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
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Specifying attributes of variables.<br>
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<b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
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<tt>deprecated</tt>, <tt>transparent_union</tt>,
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<tt>unused</tt>, <tt>weak</tt><br>
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<b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
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<tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
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<tt>vector_size</tt>, <tt>dllimport</tt>,
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<tt>dllexport</tt>, all target specific attributes.</li>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
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<b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
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<tt>deprecated</tt>, <tt>may_alias</tt><br>
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<b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
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all target specific attributes.</li>
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<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
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Other built-in functions.<br>
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We support all builtins which have a C language equivalent (e.g.,
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<tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
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<tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
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<tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
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</ol>
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<p>The following extensions <b>are</b> known to be supported:</p>
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<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
|
|
has not been tested as thoroughly as the C front-end. It has been tested and
|
|
works for a number of non-trivial programs, but there may be lurking bugs.
|
|
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>
|
|
|
|
<li>
|
|
<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=137">
|
|
Code is generated for empty classes.
|
|
</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>.</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 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_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/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>
|
|
|
|
<li>
|
|
<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=167">
|
|
The llc program can crash on legal code.
|
|
</a>
|
|
</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>
|
|
|
|
</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 and 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 <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
|
|
lists</a>.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
<hr>
|
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<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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