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| <title>LLVM 2.8 Release Notes</title> |
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| <body> |
| |
| <div class="doc_title">LLVM 2.8 Release Notes</div> |
| |
| <img align=right src="http://llvm.org/img/DragonSmall.png" |
| width="136" height="136" alt="LLVM Dragon Logo"> |
| |
| <ol> |
| <li><a href="#intro">Introduction</a></li> |
| <li><a href="#subproj">Sub-project Status Update</a></li> |
| <li><a href="#externalproj">External Projects Using LLVM 2.8</a></li> |
| <li><a href="#whatsnew">What's New in LLVM 2.8?</a></li> |
| <li><a href="GettingStarted.html">Installation Instructions</a></li> |
| <li><a href="#portability">Portability and Supported Platforms</a></li> |
| <li><a href="#knownproblems">Known Problems</a></li> |
| <li><a href="#additionalinfo">Additional Information</a></li> |
| </ol> |
| |
| <div class="doc_author"> |
| <p>Written by the <a href="http://llvm.org">LLVM Team</a></p> |
| </div> |
| |
| <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8 |
| release.<br> |
| You may prefer the |
| <a href="http://llvm.org/releases/2.7/docs/ReleaseNotes.html">LLVM 2.7 |
| Release Notes</a>.</h1> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="intro">Introduction</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This document contains the release notes for the LLVM Compiler |
| Infrastructure, release 2.8. Here we describe the status of LLVM, including |
| major improvements from the previous release and significant known problems. |
| All LLVM releases may be downloaded from the <a |
| href="http://llvm.org/releases/">LLVM releases web site</a>.</p> |
| |
| <p>For more information about LLVM, including information about the latest |
| release, please check out the <a href="http://llvm.org/">main LLVM |
| web site</a>. If you have questions or comments, the <a |
| href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's |
| Mailing List</a> is a good place to send them.</p> |
| |
| <p>Note that if you are reading this file from a Subversion checkout or the |
| main LLVM web page, this document applies to the <i>next</i> release, not the |
| current one. To see the release notes for a specific release, please see the |
| <a href="http://llvm.org/releases/">releases page</a>.</p> |
| |
| </div> |
| |
| |
| <!-- |
| Almost dead code. |
| include/llvm/Analysis/LiveValues.h => Dan |
| lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8. |
| llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8. |
| ABCD, GEPSplitterPass |
| MSIL backend? |
| lib/Transforms/Utils/SSI.cpp -> ABCD depends on it. |
| --> |
| |
| |
| <!-- Features that need text if they're finished for 2.8: |
| combiner-aa? |
| strong phi elim |
| llvm.dbg.value: variable debug info for optimized code |
| loop dependence analysis |
| --> |
| |
| <!-- for announcement email: |
| Logo web page. |
| Many new papers added to /pubs/ |
| --> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="subproj">Sub-project Status Update</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| <p> |
| The LLVM 2.8 distribution currently consists of code from the core LLVM |
| repository (which roughly includes the LLVM optimizers, code generators |
| and supporting tools), the Clang repository and the llvm-gcc repository. In |
| addition to this code, the LLVM Project includes other sub-projects that are in |
| development. Here we include updates on these subprojects. |
| </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C, |
| C++, and Objective-C languages. Clang aims to provide a better user experience |
| through expressive diagnostics, a high level of conformance to language |
| standards, fast compilation, and low memory use. Like LLVM, Clang provides a |
| modular, library-based architecture that makes it suitable for creating or |
| integrating with other development tools. Clang is considered a |
| production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p> |
| |
| <p>In the LLVM 2.8 time-frame, the Clang team has made many improvements:</p> |
| |
| <ul> |
| |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="clangsa">Clang Static Analyzer</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a> |
| project is an effort to use static source code analysis techniques to |
| automatically find bugs in C and Objective-C programs (and hopefully <a |
| href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the |
| future</a>!). The tool is very good at finding bugs that occur on specific |
| paths through code, such as on error conditions.</p> |
| |
| <p>In the LLVM 2.8 time-frame, |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of |
| a JVM and a CLI Virtual Machine (Microsoft .NET is an |
| implementation of the CLI) using LLVM for static and just-in-time |
| compilation.</p> |
| |
| <p>With the release of LLVM 2.8, ...</p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a> |
| is a simple library that provides an implementation of the low-level |
| target-specific hooks required by code generation and other runtime components. |
| For example, when compiling for a 32-bit target, converting a double to a 64-bit |
| unsigned integer is compiled into a runtime call to the "__fixunsdfdi" |
| function. The compiler-rt library provides highly optimized implementations of |
| this and other low-level routines (some are 3x faster than the equivalent |
| libgcc routines).</p> |
| |
| <p> |
| All of the code in the compiler-rt project is available under the standard LLVM |
| License, a "BSD-style" license. New in LLVM 2.8: |
| |
| Soft float support |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| <a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to |
| gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying |
| gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications |
| whatsoever (currently one small patch is needed). This is thanks to the new |
| <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which |
| makes it possible to modify the behaviour of gcc at runtime by loading a plugin, |
| which is nothing more than a dynamic library which conforms to the gcc plugin |
| interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run |
| instead of the gcc optimizers, and the LLVM code generators instead of the gcc |
| code generators, just like llvm-gcc. To use it, you add |
| "-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically |
| becomes llvm-gcc-4.5! |
| </p> |
| |
| <p> |
| DragonEgg is still a work in progress. Currently C works very well, while C++, |
| Ada and Fortran work fairly well. All other languages either don't work at all, |
| or only work poorly. For the moment only the x86-32 and x86-64 targets are |
| supported, and only on linux and darwin (darwin needs an additional gcc patch). |
| </p> |
| |
| <p> |
| 2.8 status here. |
| </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="mc">llvm-mc: Machine Code Toolkit</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p> |
| The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number |
| of problems in the realm of assembly, disassembly, object file format handling, |
| and a number of other related areas that CPU instruction-set level tools work |
| in. It is a sub-project of LLVM which provides it with a number of advantages |
| over other compilers that do not have tightly integrated assembly-level tools. |
| For a gentle introduction, please see the <a |
| href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the |
| LLVM MC Project Blog Post</a>. |
| </p> |
| |
| <p>2.8 status here</p> |
| </div> |
| |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="externalproj">External Open Source Projects Using LLVM 2.8</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>An exciting aspect of LLVM is that it is used as an enabling technology for |
| a lot of other language and tools projects. This section lists some of the |
| projects that have already been updated to work with LLVM 2.8.</p> |
| </div> |
| |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="whatsnew">What's New in LLVM 2.8?</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This release includes a huge number of bug fixes, performance tweaks and |
| minor improvements. Some of the major improvements and new features are listed |
| in this section. |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="orgchanges">LLVM Community Changes</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>In addition to changes to the code, between LLVM 2.7 and 2.8, a number of |
| organization changes have happened: |
| </p> |
| |
| <ul> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="majorfeatures">Major New Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>LLVM 2.8 includes several major new capabilities:</p> |
| |
| <ul> |
| <li>.</li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="coreimprovements">LLVM IR and Core Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>LLVM IR has several new features for better support of new targets and that |
| expose new optimization opportunities:</p> |
| |
| <ul> |
| |
| <li>LLVM 2.8 changes the internal order of operands in <a |
| href="http://llvm.org/doxygen/classllvm_1_1InvokeInst.html"><tt>InvokeInst</tt></a> |
| and <a href="http://llvm.org/doxygen/classllvm_1_1CallInst.html"><tt>CallInst</tt></a>. |
| To be portable across releases, resort to <tt>CallSite</tt> and the |
| high-level accessors, such as <tt>getCalledValue</tt> and <tt>setUnwindDest</tt>. |
| </li> |
| <li> |
| You can no longer pass use_iterators directly to cast<> (and similar), because |
| these routines tend to perform costly dereference operations more than once. You |
| have to dereference the iterators yourself and pass them in. |
| </li> |
| <li> |
| llvm.memcpy.*, llvm.memset.*, llvm.memmove.* (and possibly other?) intrinsics |
| take an extra parameter now (i1 isVolatile), totaling 5 parameters. |
| If you were creating these intrinsic calls and prototypes yourself (as opposed |
| to using Intrinsic::getDeclaration), you can use UpgradeIntrinsicFunction/UpgradeIntrinsicCall |
| to be portable accross releases. |
| Note that you cannot use Intrinsic::getDeclaration() in a backwards compatible |
| way (needs 2/3 types now, in 2.7 it needed just 1). |
| </li> |
| <li> |
| SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode. |
| Change your code to use |
| SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)). |
| </li> |
| <li> |
| VISIBILITY_HIDDEN is gone. |
| </li> |
| <li> |
| The <tt>RegisterPass</tt> and <tt>RegisterAnalysisGroup</tt> templates are |
| considered deprecated, but continue to function in LLVM 2.8. Clients are |
| strongly advised to use the upcoming <tt>INITIALIZE_PASS()</tt> and |
| <tt>INITIALIZE_AG_PASS()</tt> macros instead. |
| <li> |
| SMDiagnostic takes different parameters now. //FIXME: how to upgrade? |
| </li> |
| <li> |
| Some APIs got renamed: |
| <ul> |
| <li>llvm_report_error -> report_fatal_error</li> |
| <li>llvm_install_error_handler -> install_fatal_error_handler</li> |
| <li>llvm::DwarfExceptionHandling -> llvm::JITExceptionHandling</li> |
| </ul> |
| </li> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="optimizer">Optimizer Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>In addition to a large array of minor performance tweaks and bug fixes, this |
| release includes a few major enhancements and additions to the optimizers:</p> |
| |
| <ul> |
| |
| <li></li> |
| |
| </ul> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="executionengine">Interpreter and JIT Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li></li> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="codegen">Target Independent Code Generator Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>We have put a significant amount of work into the code generator |
| infrastructure, which allows us to implement more aggressive algorithms and make |
| it run faster:</p> |
| |
| <ul> |
| <li>MachO writer works.</li> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="x86">X86-32 and X86-64 Target Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of the X86 target include: |
| </p> |
| |
| <ul> |
| <li>The X86 backend now supports holding X87 floating point stack values |
| in registers across basic blocks, dramatically improving performance of code |
| that uses long double, and when targetting CPUs that don't support SSE.</li> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="ARM">ARM Target Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>New features of the ARM target include: |
| </p> |
| |
| <ul> |
| |
| <li></li> |
| |
| </ul> |
| |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="newapis">New Useful APIs</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>This release includes a number of new APIs that are used internally, which |
| may also be useful for external clients. |
| </p> |
| |
| <ul> |
| <li></li> |
| </ul> |
| |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="otherimprovements">Other Improvements and New Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| <p>Other miscellaneous features include:</p> |
| |
| <ul> |
| <li></li> |
| </ul> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <div class="doc_subsection"> |
| <a name="changes">Major Changes and Removed Features</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>If you're already an LLVM user or developer with out-of-tree changes based |
| on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading |
| from the previous release.</p> |
| |
| <ul> |
| |
| <li>.</li> |
| </ul> |
| |
| <p>In addition, many APIs have changed in this release. Some of the major LLVM |
| API changes are:</p> |
| |
| <ul> |
| </ul> |
| |
| </div> |
| |
| |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="portability">Portability and Supported Platforms</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>LLVM is known to work on the following platforms:</p> |
| |
| <ul> |
| <li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat |
| Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like |
| systems).</li> |
| <li>PowerPC and X86-based Mac OS X systems, running 10.4 and above in 32-bit |
| and 64-bit modes.</li> |
| <li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li> |
| <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited |
| support is available for native builds with Visual C++).</li> |
| <li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li> |
| <li>Alpha-based machines running Debian GNU/Linux.</li> |
| </ul> |
| |
| <p>The core LLVM infrastructure uses GNU autoconf to adapt itself |
| 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 |
| portability patches and reports of successful builds or error messages.</p> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="knownproblems">Known Problems</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This section contains significant known problems with the LLVM system, |
| listed by component. 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> |
| |
| <ul> |
| <li>LLVM will not correctly compile on Solaris and/or OpenSolaris |
| using the stock GCC 3.x.x series 'out the box', |
| See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>. |
| However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a> |
| for x86/x86-64 has been made available from the third party AuroraUX Project |
| that has been meticulously tested for bootstrapping LLVM & Clang.</li> |
| <li>There have been reports of Solaris and/or OpenSolaris build failures due |
| to an incompatibility in the nm program as well. The nm from binutils does seem |
| to work.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <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> |
| <li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze |
| backends are experimental.</li> |
| <li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only |
| supported value for this option. XXX Update me</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 backend does not yet support |
| all <a href="http://llvm.org/PR879">inline assembly that uses the X86 |
| floating point stack</a>. It supports the 'f' and 't' constraints, but not |
| 'u'.</li> |
| <li>Win64 code generation wasn't widely tested. Everything should work, but we |
| expect small issues to happen. Also, llvm-gcc cannot build the mingw64 |
| runtime currently due to lack of support for the 'u' inline assembly |
| constraint and for X87 floating point inline assembly.</li> |
| <li>The X86-64 backend does not yet support the LLVM IR instruction |
| <tt>va_arg</tt>. Currently, front-ends support variadic |
| argument constructs on X86-64 by lowering them manually.</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> |
| <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> |
| </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="mips-be">Known problems with the MIPS back-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ul> |
| <li>64-bit MIPS targets are not supported yet.</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="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 has only basic support for |
| inline assembly code</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 <tt>llc</tt> or native compilers.</li> |
| <li>The C backend does not support all exception handling constructs.</li> |
| <li>The C backend does not support arbitrary precision integers.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>The only major language feature of GCC not supported by llvm-gcc is |
| the <tt>__builtin_apply</tt> family of builtins. However, some extensions |
| are only supported on some targets. For example, trampolines are only |
| supported on some targets (these are used when you take the address of a |
| nested function).</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a> |
| </div> |
| |
| <div class="doc_text"> |
| <ul> |
| <li>Fortran support generally works, but there are still several unresolved bugs |
| in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the |
| tools/gfortran component for details.</li> |
| </ul> |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="ada-fe">Known problems with the llvm-gcc 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>. |
| This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style |
| exception handling, which is used internally by the compiler. |
| Workaround: configure with <tt>--disable-bootstrap</tt>.</li> |
| <li>The c380004, <a href="http://llvm.org/PR2010">c393010</a> |
| and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail |
| (c380004 also fails with gcc-4.2 mainline). |
| If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a> |
| causes the compiler to go into an infinite loop, using up all system memory.</li> |
| <li>Some GCC specific Ada tests continue to crash the compiler.</li> |
| <li>The <tt>-E</tt> 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 <tt>-E</tt>.</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 <tt>lli</tt> 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 <tt>argv</tt> and |
| <tt>envp</tt> rather than integers.</li> |
| <li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is |
| ignored</a>.</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> |
| |
| <!-- *********************************************************************** --> |
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