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764 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 2.2 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">LLVM 2.2 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 2.2. Here we describe the status of LLVM, including
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major improvements from the previous release and any known problems. All LLVM
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releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
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releases web site</a>.</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 a Subversion checkout or the
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main LLVM web page, this document applies to the <i>next</i> release, not the
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current one. To see the release notes for a specific releases, please see the
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<a 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 thirteenth public release of the LLVM Compiler Infrastructure.
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It includes many features and refinements from LLVM 2.1.</p>
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</div>
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<!-- Unfinished features in 2.2:
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Index Set Splitting not enabled by default
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Machine LICM
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Machine Sinking
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LegalizeDAGTypes
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-->
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="deprecation">Deprecated features in LLVM 2.2</a>
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</div>
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<div class="doc_text">
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<p>This is the last LLVM release to support llvm-gcc 4.0, llvm-upgrade, and
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llvmc in its current form. llvm-gcc 4.0 has been replaced with llvm-gcc 4.2.
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llvm-upgrade is useful for upgrading llvm 1.9 files to llvm 2.x syntax, but you
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can always use an old release to do this. llvmc is currently mostly useless in
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llvm 2.2, and will be redesigned or removed in llvm 2.3.</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
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</div>
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<div class="doc_text">
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<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
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LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
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has made leaps and bounds and is now at least as good as 4.0 in virtually every
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area, and is better in several areas (for example, exception handling
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correctness, support for Ada and Fortran, better ABI compatibility, etc). We
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strongly recommend that you
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migrate from llvm-gcc 4.0 to llvm-gcc 4.2 in this release cycle because
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<b>LLVM 2.2 is the last release that will support llvm-gcc 4.0</b>: LLVM 2.3
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will only support the llvm-gcc 4.2 front-end.</p>
|
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<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
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a set of new 'llvm native' front-end technologies for the LLVM optimizer
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and code generator. Currently, its C and Objective-C support is maturing
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nicely, and it has advanced source-to-source analysis and transformation
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capabilities. If you are interested in building source-level tools for C and
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Objective-C (and eventually C++), you should take a look. However, note that
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clang is not an official part of the LLVM 2.2 release. If you are interested in
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this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="majorfeatures">Major New Features</a>
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</div>
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<div class="doc_text">
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<p>LLVM 2.2 includes several major new capabilities:</p>
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<ul>
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<li>A research team led by Scott Michel in the Computer Systems Research
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Department at The Aerospace Corporation contributed the CellSPU backend, which
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generates code for the vector coprocessors on the Sony/Toshiba/IBM Cell BE
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processor. llvm-gcc 4.2 supports CellSPU as a 'configure' target and progress
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is being made so that libgcc.a compiles cleanly. Notable pieces still in
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development include full 64-bit integer and full double precision floating
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point support.</li>
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<li>Anton and Duncan significantly improved llvm-gcc 4.2 support for the GCC Ada
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(GNAT) and Fortran (gfortran) front-ends. These front-ends should still be considered
|
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experimental however: see the <a href="#knownproblems">list of known problems</a>.
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The release binaries do not contain either front-end: they need to be built from
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source (the Ada front-end only builds on x86-32 linux).</li>
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<li>Dale contributed full support for long double on x86/x86-64 (where it is 80
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bits) and on Darwin PPC/PPC64 (where it is 128 bits). In previous LLVM
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releases, llvm-gcc silently mapped long double to double.</li>
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<li>Gordon Henriksen rewrote most of the <a href="GarbageCollection.html"
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>Accurate Garbage Collection</a> code in the code generator, making the
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generated code more efficient and adding support for the OCaml garbage collector
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metadata format.</li>
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<li>Christopher Lamb contributed support for multiple address spaces in LLVM
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IR. This is useful for supporting targets that have 'near' vs 'far' pointers,
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'RAM' vs 'ROM' pointers, or that have non-local memory that can be accessed with
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special instructions.</li>
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<li>LLVM now includes a new set of detailed <a
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href="tutorial/index.html">tutorials</a>, which explain how to implement a
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language with LLVM and shows how to use several important APIs.</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="coreimprovements">LLVM Core Improvements</a>
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</div>
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<div class="doc_text">
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<p>New features include:
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</p>
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<ul>
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<li>Gordon contributed support for C and OCaml Bindings for the basic LLVM IR
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construction routines as well as several other auxiliary APIs.</li>
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<li>Anton added readnone/readonly attributes for modeling function side effects.
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Duncan hooked up GCC's pure/const attributes to them and enhanced mod/ref
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analysis to use them.</li>
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<li>Devang added LLVMFoldingBuilder, a version of LLVMBuilder that implicitly
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simplifies the code as it is constructed.</li>
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<li>Ted Kremenek added a framework for generic object serialization to bitcode
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files. This support is only used by clang right now for ASTs but is extensible
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and could be used for serializing arbitrary other data into bitcode files.</li>
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<li>Duncan improved TargetData to distinguish between the size/alignment of a
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type in a register, in memory according to the platform ABI, and in memory when
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we have a choice.</li>
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<li>Reid moved parameter attributes off of FunctionType and onto functions
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and calls. This makes it much easier to add attributes to a function in a
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transformation pass.</li>
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<li>Dan Gohman added support for vector sin, cos, and pow intrinsics.</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="codegen">Code Generator Improvements</a>
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</div>
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<div class="doc_text">
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<p>We put a significant amount of work into the code generator infrastructure,
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which allows us to implement more aggressive algorithms and make it run
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faster:</p>
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<ul>
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<li>Owen refactored the existing LLVM dominator and loop information code to
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allow it work on the machine code representation. He contributed support for
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dominator and loop information on machine code and merged the code for forward
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and backward dominator computation.</li>
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<li>Dan added support for emitting debug information with .file and .loc
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directives on platforms that support it, instead of emitting large tables in the .s
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file.</li>
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<li>Evan extended the DAG scheduler to model physical register dependencies
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explicitly and have the BURR scheduler pick a correct schedule based on the
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dependencies. This reduces our use of the 'flag' operand hack.</li>
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<li>Evan added initial support for register coalescing of subregister
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references.</li>
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<li>Rafael Espindola implemented initial support for a new 'byval' attribute,
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which allows more efficient by-value argument passing in the LLVM IR. Evan
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finished support for it and enabled it in the X86 (32- and 64-bit) and C
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backends.</li>
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<li>The LLVM TargetInstrInfo class can now answer queries about the mod/ref and
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side-effect behavior of MachineInstr's. This information is inferred
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automatically by TableGen from .td files for all instructions with
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patterns.</li>
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<li>Evan implemented simple live interval splitting on basic block boundaries.
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This allows the register allocator to be more successful at keeping values in
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registers in some parts of a value's live range, even if they need to be spilled
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in some other block.</li>
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<li>The new MachineRegisterInfo.h class provides support for efficiently
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iterating over all defs/uses of a register, and this information is
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automatically kept up-to-date. This support is similar to the use_iterator in
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the LLVM IR level.</li>
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<li>The MachineInstr, MachineOperand and TargetInstrDesc classes are simpler,
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more consistent, and better documented.</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="optimizer">Optimizer Improvements</a>
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</div>
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<div class="doc_text">
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<p>In addition to a huge array of bug fixes and minor performance tweaks, the
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LLVM 2.2 optimizers support a few major enhancements:</p>
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<ul>
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<li>Daniel Berlin and Curtis Dunham rewrote Andersen's alias analysis to be
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several orders of magnitude faster, and implemented Offline Variable
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Substitution and Lazy Cycle Detection. Note that Andersen's is not enabled in
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llvm-gcc by default, but can be accessed through 'opt'.</li>
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<li>Dan Gohman contributed several enhancements to Loop Strength Reduction (LSR)
|
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to make it more aggressive with SSE intrinsics and when induction variables are
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used by non-memory instructions.</li>
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<li>Evan added support for simple exit value substitution to LSR.</li>
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|
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<li>Evan enhanced LSR to support induction variable reuse when the induction
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variables have different widths.</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="targetspecific">Target Specific Improvements</a>
|
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</div>
|
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|
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<div class="doc_text">
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<p>New target-specific features include:
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</p>
|
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<ul>
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<li>Evan contributed support to the X86 backend to model the mod/ref behavior
|
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of the EFLAGS register explicitly in all instructions. This gives more freedom
|
|
to the scheduler, and is a more explicit way to model the instructions.</li>
|
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<li>Dale contributed support for exception handling on Darwin/PPC and he and
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Anton got x86-64 working.</li>
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<li>Evan turned on if-conversion by default for ARM, allowing LLVM to take
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advantage of its predication features.</li>
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<li>Bruno added PIC support to the MIPS backend, fixed many bugs and improved
|
|
support for architecture variants.</li>
|
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<li>Arnold Schwaighofer added support for X86 tail calls (limitations?
|
|
details?).</li>
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<li>Evan contributed several enhancements to Darwin/x86 debug information,
|
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and improvements at -O0 (details?).</li>
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<li>Duncan added x86-64 support for trampolines (pointers to nested functions).</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="otherimprovements">Other Improvements</a>
|
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</div>
|
|
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<div class="doc_text">
|
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<p>New features include:
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</p>
|
|
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<ul>
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<li>Gordon expanded and updated the <a href="Passes.html">LLVM Analysis and
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|
Transformation Passes</a> reference to include descriptions for each pass.</li>
|
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<li>We rewrote the lexer and parser used by TableGen to make them simpler
|
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and cleaner. This gives tblgen support for 'caret diagnostics'. The .ll file
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lexer was also rewritten to support caret diagnostics but doesn't use this
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support yet.</li>
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<li>Dale has been grinding through the GCC testsuite, and marked many
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LLVM-incompatible tests as not-to-be-run (for example, if they are grepping
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through some GCC dump file that LLVM doesn't produce), he also found and fixed
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many LLVM bugs exposed by the testsuite.</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>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
|
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64-bit modes.</li>
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<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</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>Sun UltraSPARC workstations running Solaris 8.</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
|
|
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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|
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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>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
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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
|
|
component. As new problems are discovered, they will be added to these
|
|
sections. If you run into a problem, please check the <a
|
|
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
|
|
there isn't already one.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
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<div class="doc_subsection">
|
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<a name="experimental">Experimental features included with this release</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The following components of this LLVM release are either untested, known to
|
|
be broken or unreliable, or are in early development. These components should
|
|
not be relied on, and bugs should not be filed against them, but they may be
|
|
useful to some people. In particular, if you would like to work on one of these
|
|
components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
|
|
|
|
<ul>
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<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
|
|
LLVM 2.3.</li>
|
|
<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
|
|
<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
|
|
value for this option.</li>
|
|
<li>The llvmc tool is not supported.</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>
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|
<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
|
|
assembly that uses the X86 floating point stack</a>.</li>
|
|
<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
|
|
problems</a> on operating systems that don't require 16-byte stack alignment
|
|
(including most non-darwin OS's like linux).</li>
|
|
<li>The X86 backend generates inefficient floating point code when configured to
|
|
generate code for systems that don't have SSE2.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ppc-be">Known problems with the PowerPC back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The Linux PPC32/ABI support needs testing for the interpreter and static
|
|
compilation, and lacks support for debug information.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="arm-be">Known problems with the ARM back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
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|
<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
|
|
processors, thumb programs can crash or produce wrong
|
|
results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
|
|
<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
|
|
</li>
|
|
<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
|
|
programs compiled with LLVM. Please use more recent versions of QEMU.</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 backend only supports the 32-bit SPARC ABI (-m32), it does not
|
|
support the 64-bit SPARC ABI (-m64).</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="alpha-be">Known problems with the Alpha back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
|
|
appropriate nops inserted to ensure restartability.</li>
|
|
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ia64-be">Known problems with the IA64 back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
|
|
<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
|
|
made where the argument is not 16-byte aligned, as required on IA64. (Strictly
|
|
speaking this is not a bug in the IA64 back-end; it will also be encountered
|
|
when building C++ programs using the C back-end.)</li>
|
|
|
|
<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
|
|
ABI compliant layout of v-tables</a>. In particular, it just stores function
|
|
pointers instead of function descriptors in the vtable. This bug prevents
|
|
mixing C++ code compiled with LLVM with C++ objects compiled by other C++
|
|
compilers.</li>
|
|
|
|
<li>There are a few ABI violations which will lead to problems when mixing LLVM
|
|
output with code built with other compilers, particularly for floating-point
|
|
programs.</li>
|
|
|
|
<li>Defining vararg functions is not supported (but calling them is ok).</li>
|
|
|
|
<li>The Itanium backend has bitrotted somewhat.</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><a href="http://llvm.org/PR802">The C backend does not support inline
|
|
assembly code</a>.</li>
|
|
<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
|
|
yet</a>.</li>
|
|
<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
|
|
C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
|
|
C++ code compiled with LLC or native compilers.</li>
|
|
<li>The C backend does not support all exception handling constructs.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c-fe">Known problems with the C front-end</a>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ada-fe">Known problems with the Ada front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
|
|
technology and problems should be expected.
|
|
<ul>
|
|
<li>The Ada front-end currently only builds on x86-32. This is mainly due
|
|
to lack of trampoline support (pointers to nested functions) on other platforms,
|
|
however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
|
|
which does support trampolines.</li>
|
|
<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
|
|
Workaround: configure with --disable-bootstrap.</li>
|
|
<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
|
|
fail (c380004 also fails with gcc-4.2 mainline).</li>
|
|
<li>Many gcc specific Ada tests continue to crash the compiler.</li>
|
|
<li>The -E binder option (exception backtraces)
|
|
<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
|
|
crashing if an exception is raised. Workaround: do not use -E.</li>
|
|
<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
|
|
or finish at a non-byte offset</a> in a record. Workaround: do not pack records
|
|
or use representation clauses that result in a field of a non-discrete type
|
|
starting or finishing in the middle of a byte.</li>
|
|
<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
|
|
as generated by the Ada binder to be invalid</a>.
|
|
Workaround: hand edit the file to use pointers for argv and envp rather than
|
|
integers.</li>
|
|
<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="fortran-fe">Known problems with the Fortran front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
|
|
<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">Bugs</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
|
|
Optimization</a> on most platforms "out-of-the-box". Please inquire on the
|
|
llvmdev mailing list if you are interested.</p>
|
|
|
|
</div>
|
|
|
|
<!-- _______________________________________________________________________ -->
|
|
<div class="doc_subsubsection">
|
|
Notes
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<ul>
|
|
|
|
<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
|
|
See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
|
|
</li>
|
|
|
|
<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
|
|
<ol>
|
|
<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.
|
|
Nested functions are supported, but llvm-gcc does not support
|
|
taking the address of a nested function (except on X86 targets)
|
|
or non-local gotos.</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>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
|
|
<tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
|
|
<tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
|
|
<tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
|
|
<tt>noreturn</tt>, <tt>nothrow</tt>, <tt>pure</tt>, <tt>regparm</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>malloc</tt>,
|
|
<tt>no_instrument_function</tt></li>
|
|
</ol>
|
|
</li>
|
|
|
|
<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
|
|
|
|
<ol>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
|
|
<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/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
|
|
Other built-in functions.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
|
|
Specifying attributes of variables.</li>
|
|
<li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</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/Variable-Length.html#Variable%20Length">Variable Length</a>:
|
|
Arrays whose length is computed at run time.</li>
|
|
<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>The C++ front-end is considered to be fully
|
|
tested and works for a number of non-trivial programs, including LLVM
|
|
itself, Qt, Mozilla, etc.</p>
|
|
|
|
<ul>
|
|
<li>Exception handling only works well on the X86 and PowerPC targets.
|
|
It works well for x86-64 darwin but not x86-64 linux.</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>, in particular in the <a
|
|
href="http://llvm.org/docs/">documentation</a> section. The web page also
|
|
contains versions of the API documentation which is up-to-date with the
|
|
Subversion 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>
|
|
<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.org/">LLVM Compiler Infrastructure</a><br>
|
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Last modified: $Date$
|
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