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author | Bill Wendling <isanbard@gmail.com> | 2010-10-04 19:55:17 +0000 |
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committer | Bill Wendling <isanbard@gmail.com> | 2010-10-04 19:55:17 +0000 |
commit | 304d1811007489de43a5408081c1e2dcc76435e0 (patch) | |
tree | f90c35c26fe79165246651f201ce4654e23960d7 | |
parent | b031f70bd1f377291f617ed5d061935e6b7485e5 (diff) | |
download | llvm-304d1811007489de43a5408081c1e2dcc76435e0.zip llvm-304d1811007489de43a5408081c1e2dcc76435e0.tar.gz llvm-304d1811007489de43a5408081c1e2dcc76435e0.tar.bz2 |
Update release notes for 2.8 release.
llvm-svn: 115548
-rw-r--r-- | llvm/docs/ReleaseNotes.html | 982 |
1 files changed, 706 insertions, 276 deletions
diff --git a/llvm/docs/ReleaseNotes.html b/llvm/docs/ReleaseNotes.html index e6249a6..a8c2005 100644 --- a/llvm/docs/ReleaseNotes.html +++ b/llvm/docs/ReleaseNotes.html @@ -3,6 +3,7 @@ <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> + <meta encoding="utf8"> <link rel="stylesheet" href="llvm.css" type="text/css"> <title>LLVM 2.8 Release Notes</title> </head> @@ -19,7 +20,6 @@ <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> @@ -28,11 +28,13 @@ <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"> @@ -66,23 +68,20 @@ current one. To see the release notes for a specific release, please see the 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. GEPSplitterPass --> -<!-- Features that need text if they're finished for 2.8: +<!-- Features that need text if they're finished for 2.9: combiner-aa? strong phi elim - llvm.dbg.value: variable debug info for optimized code loop dependence analysis TBAA + CorrelatedValuePropagation --> - - <!-- for announcement email: - Logo web page. - Many new papers added to /pubs/ - --> + + <!-- Announcement, lldb, libc++ --> + <!-- *********************************************************************** --> <div class="doc_section"> @@ -115,13 +114,32 @@ 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> +production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86 +(32- and 64-bit), and for darwin-arm targets.</p> <p>In the LLVM 2.8 time-frame, the Clang team has made many improvements:</p> -<ul> - -</ul> + <ul> + <li>Clang C++ is now feature-complete with respect to the ISO C++ 1998 and 2003 standards.</li> + <li>Added support for Objective-C++.</li> + <li>Clang now uses LLVM-MC to directly generate object code and to parse inline assembly (on Darwin).</li> + <li>Introduced many new warnings, including <code>-Wmissing-field-initializers</code>, <code>-Wshadow</code>, <code>-Wno-protocol</code>, <code>-Wtautological-compare</code>, <code>-Wstrict-selector-match</code>, <code>-Wcast-align</code>, <code>-Wunused</code> improvements, and greatly improved format-string checking.</li> + <li>Introduced the "libclang" library, a C interface to Clang intended to support IDE clients.</li> + <li>Added support for <code>#pragma GCC visibility</code>, <code>#pragma align</code>, and others.</li> + <li>Added support for SSE, ARM NEON, and Altivec.</li> + <li>Improved support for many Microsoft extensions.</li> + <li>Implemented support for blocks in C++.</li> + <li>Implemented precompiled headers for C++.</li> + <li>Improved abstract syntax trees to retain more accurate source information.</li> + <li>Added driver support for handling LLVM IR and bitcode files directly.</li> + <li>Major improvements to compiler correctness for exception handling.</li> + <li>Improved generated code quality in some areas: + <ul> + <li>Good code generation for X86-32 and X86-64 ABI handling.</li> + <li>Improved code generation for bit-fields, although important work remains.</li> + </ul> + </li> + </ul> </div> <!--=========================================================================--> @@ -138,27 +156,64 @@ production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p> 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>The LLVM 2.8 release fixes a number of bugs and slightly improves precision + over 2.7, but there are no major new features in the release. </p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a> +<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</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> +<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to +gcc-4.5. Unlike llvm-gcc, dragonegg in theory does not require any gcc-4.5 +modifications whatsoever (currently one small patch is needed) thanks to the +new <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>. +DragonEgg is a gcc plugin that makes gcc-4.5 use the LLVM optimizers and code +generators instead of gcc's, just like with llvm-gcc. +</p> + +<p> +DragonEgg is still a work in progress, but it is able to compile a lot of code, +for example all of gcc, LLVM and clang. Currently Ada, C, C++ and Fortran work +well, while 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 may need additional gcc patches). +</p> + +<p> +The 2.8 release has the following notable changes: +<ul> +<li>The plugin loads faster due to exporting fewer symbols.</li> +<li>Additional vector operations such as addps256 are now supported.</li> +<li>Ada global variables with no initial value are no longer zero initialized, +resulting in better optimization.</li> +<li>The '-fplugin-arg-dragonegg-enable-gcc-optzns' flag now runs all gcc +optimizers, rather than just a handful.</li> +<li>Fortran programs using common variables now link correctly.</li> +<li>GNU OMP constructs no longer crash the compiler.</li> +</ul> -<p>With the release of LLVM 2.8, ...</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 Java Virtual Machine (Java VM or JVM) that uses LLVM for static and +just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage +collectors, and can be configured to use MMTk's copy mark-sweep garbage +collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained. +</p> +</div> <!--=========================================================================--> <div class="doc_subsection"> @@ -178,67 +233,91 @@ 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> +License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports +soft floating point (for targets that don't have a real floating point unit), +and includes an extensive testsuite for the "blocks" language feature and the +blocks runtime included in compiler_rt.</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a> +<a name="lldb">LLDB: Low Level Debugger</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> +<a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM +umbrella of projects. LLDB is a next generation, high-performance debugger. It +is built as a set of reusable components which highly leverage existing +libraries in the larger LLVM Project, such as the Clang expression parser, the +LLVM disassembler and the LLVM JIT.</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). +LLDB is in early development and not included as part of the LLVM 2.8 release, +but is mature enough to support basic debugging scenarios on Mac OS X in C, +Objective-C and C++. We'd really like help extending and expanding LLDB to +support new platforms, new languages, new architectures, and new features. </p> +</div> + +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="libc++">libc++: C++ Standard Library</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://libc++.llvm.org/">libc++</a> is another new member of the LLVM +family. It is an implementation of the C++ standard library, written from the +ground up to specifically target the forthcoming C++'0X standard and focus on +delivering great performance.</p> + <p> -2.8 status here. +As of the LLVM 2.8 release, libc++ is virtually feature complete, but would +benefit from more testing and better integration with Clang++. It is also +looking forward to the C++ committee finalizing the C++'0x standard. </p> </div> + <!--=========================================================================--> <div class="doc_subsection"> -<a name="mc">llvm-mc: Machine Code Toolkit</a> +<a name="klee">KLEE: A Symbolic Execution Virtual Machine</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>. +<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for +programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths +through the application and records state transitions that lead to fault +states. This allows it to construct testcases that lead to faults and can even +be used to verify some algorithms. </p> -<p>2.8 status here</p> -</div> +<p>Although KLEE does not have any major new features as of 2.8, we have made +various minor improvements, particular to ease development:</p> +<ul> + <li>Added support for LLVM 2.8. KLEE currently maintains compatibility with + LLVM 2.6, 2.7, and 2.8.</li> + <li>Added a buildbot for 2.6, 2.7, and trunk. A 2.8 buildbot will be coming + soon following release.</li> + <li>Fixed many C++ code issues to allow building with Clang++. Mostly + complete, except for the version of MiniSAT which is inside the KLEE STP + version.</li> + <li>Improved support for building with separate source and build + directories.</li> + <li>Added support for "long double" on x86.</li> + <li>Initial work on KLEE support for using 'lit' test runner instead of + DejaGNU.</li> + <li>Added <tt>configure</tt> support for using an external version of + STP.</li> +</ul> + +</div> <!-- *********************************************************************** --> @@ -254,298 +333,699 @@ LLVM MC Project Blog Post</a>. 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 class="doc_subsection"> +<a name="tce">TTA-based Codesign Environment (TCE)</a> </div> -<!-- *********************************************************************** --> <div class="doc_text"> +<p> +<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing +application-specific processors (ASP) based on the Transport triggered +architecture (TTA). The toolset provides a complete co-design flow from C/C++ +programs down to synthesizable VHDL and parallel program binaries. Processor +customization points include the register files, function units, supported +operations, and the interconnection network.</p> -<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> +<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target +independent optimizations and also for parts of code generation. It generates +new LLVM-based code generators "on the fly" for the designed TTA processors and +loads them in to the compiler backend as runtime libraries to avoid per-target +recompilation of larger parts of the compiler chain.</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="orgchanges">LLVM Community Changes</a> +<a name="Horizon">Horizon Bytecode Compiler</a> </div> <div class="doc_text"> +<p> +<a href="http://www.quokforge.org/projects/horizon">Horizon</a> is a bytecode +language and compiler written on top of LLVM, intended for producing +single-address-space managed code operating systems that +run faster than the equivalent multiple-address-space C systems. +More in-depth blurb is available on the <a +href="http://www.quokforge.org/projects/horizon/wiki/Wiki">wiki</a>.</p> + +</div> -<p>In addition to changes to the code, between LLVM 2.7 and 2.8, a number of -organization changes have happened: +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="clamav">Clam AntiVirus</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://www.clamav.net">Clam AntiVirus</a> is an open source (GPL) +anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail +gateways. Since version 0.96 it has <a +href="http://vrt-sourcefire.blogspot.com/2010/09/introduction-to-clamavs-low-level.html">bytecode +signatures</a> that allow writing detections for complex malware. It +uses LLVM's JIT to speed up the execution of bytecode on +X86, X86-64, PPC32/64, falling back to its own interpreter otherwise. +The git version was updated to work with LLVM 2.8. </p> -<ul> -</ul> +<p>The <a +href="http://git.clamav.net/gitweb?p=clamav-bytecode-compiler.git;a=blob_plain;f=docs/user/clambc-user.pdf"> +ClamAV bytecode compiler</a> uses Clang and LLVM to compile a C-like +language, insert runtime checks, and generate ClamAV bytecode.</p> + </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="majorfeatures">Major New Features</a> +<a name="pure">Pure</a> </div> <div class="doc_text"> +<p> +<a href="http://pure-lang.googlecode.com/">Pure</a> +is an algebraic/functional +programming language based on term rewriting. Programs are collections +of equations which are used to evaluate expressions in a symbolic +fashion. Pure offers dynamic typing, eager and lazy evaluation, lexical +closures, a hygienic macro system (also based on term rewriting), +built-in list and matrix support (including list and matrix +comprehensions) and an easy-to-use C interface. The interpreter uses +LLVM as a backend to JIT-compile Pure programs to fast native code.</p> -<p>LLVM 2.8 includes several major new capabilities:</p> - -<ul> -<li>.</li> -</ul> +<p>Pure versions 0.44 and later have been tested and are known to work with +LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="coreimprovements">LLVM IR and Core Improvements</a> +<a name="GHC">Glasgow Haskell Compiler (GHC)</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> +<p> +<a href="http://www.haskell.org/ghc/">GHC</a> is an open source, +state-of-the-art programming suite for +Haskell, a standard lazy functional programming language. It includes +an optimizing static compiler generating good code for a variety of +platforms, together with an interactive system for convenient, quick +development.</p> -<ul> +<p>In addition to the existing C and native code generators, GHC 7.0 now +supports an <a +href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM +code generator</a>. GHC supports LLVM 2.7 and later.</p> -<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> -The <tt>Pass(intptr_t)</tt> and <tt>Pass(const void*)</tt> got replaced with a -<tt>Pass(char&)</tt> constructor. This means you have to use ifdefs if you -want your pass to work with both LLVM 2.7 and 2.8 -</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> - The constructor for the Triple class no longer tries to understand odd triple - specifications. Frontends should ensure that they only pass valid triples to - LLVM. The Triple::normalize utility method has been added to help front-ends - deal with funky triples. -<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="Clay">Clay Programming Language</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://tachyon.in/clay/">Clay</a> is a new systems programming +language that is specifically designed for generic programming. It makes +generic programming very concise thanks to whole program type propagation. It +uses LLVM as its backend.</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="optimizer">Optimizer Improvements</a> +<a name="llvm-py">llvm-py Python Bindings for LLVM</a> </div> <div class="doc_text"> +<p> +<a href="http://www.mdevan.org/llvm-py/">llvm-py</a> has been updated to work +with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a +compiler backend or a VM in Python.</p> -<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> +</div> -<ul> -<li></li> +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://faust.grame.fr">FAUST</a> is a compiled language for real-time +audio signal processing. The name FAUST stands for Functional AUdio STream. Its +programming model combines two approaches: functional programming and block +diagram composition. In addition with the C, C++, JAVA output formats, the +Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and +2.8.</p> -</ul> +</div> +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="jade">Jade Just-in-time Adaptive Decoder Engine</a> </div> +<div class="doc_text"> +<p><a +href="http://sourceforge.net/apps/trac/orcc/wiki/JadeDocumentation">Jade</a> +(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using +LLVM for just-in-time compilation of video decoder configurations. Those +configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee. +MPEG RVC standard is built on a stream-based dataflow representation of +decoders. It is composed of a standard library of coding tools written in +RVC-CAL language and a dataflow configuration — block diagram — +of a decoder.</p> + +<p>Jade project is hosted as part of the <a href="http://orcc.sf.net">Open +RVC-CAL Compiler</a> and requires it to translate the RVC-CAL standard library +of video coding tools into an LLVM assembly code.</p> + +</div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="executionengine">Interpreter and JIT Improvements</a> +<a name="neko_llvm_jit">LLVM JIT for Neko VM</a> </div> <div class="doc_text"> +<p><a href="http://github.com/vava/neko_llvm_jit">Neko LLVM JIT</a> +replaces the standard Neko JIT with an LLVM-based implementation. While not +fully complete, it is already providing a 1.5x speedup on 64-bit systems. +Neko LLVM JIT requires LLVM 2.8 or later.</p> -<ul> -<li></li> +</div> -</ul> +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="crack">Crack Scripting Language</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide +the ease of development of a scripting language with the performance of a +compiled language. The language derives concepts from C++, Java and Python, +incorporating object-oriented programming, operator overloading and strong +typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release +builds on LLVM 2.8.</p> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="codegen">Target Independent Code Generator Improvements</a> +<a name="DresdenTM">Dresden TM Compiler (DTMC)</a> </div> <div class="doc_text"> +<p> +<a href="http://tm.inf.tu-dresden.de">DTMC</a> provides support for +Transactional Memory, which is an easy-to-use and efficient way to synchronize +accesses to shared memory. Transactions can contain normal C/C++ code (e.g., +<code>__transaction { list.remove(x); x.refCount--; }</code>) and will be executed +virtually atomically and isolated from other transactions.</p> -<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> +</div> + +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="Kai">Kai Programming Language</a> +</div> + +<div class="doc_text"> +<p> +<a href="http://www.oriontransfer.co.nz/research/kai">Kai</a> (Japanese 会 for +meeting/gathering) is an experimental interpreter that provides a highly +extensible runtime environment and explicit control over the compilation +process. Programs are defined using nested symbolic expressions, which are all +parsed into first-class values with minimal intrinsic semantics. Kai can +generate optimised code at run-time (using LLVM) in order to exploit the nature +of the underlying hardware and to integrate with external software libraries. +It is a unique exploration into world of dynamic code compilation, and the +interaction between high level and low level semantics.</p> -<ul> -<li>MachO writer works.</li> -</ul> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="x86">X86-32 and X86-64 Target Improvements</a> +<a name="OSL">OSL: Open Shading Language</a> </div> <div class="doc_text"> -<p>New features of the X86 target include: +<p> +<a href="http://code.google.com/p/openshadinglanguage/">OSL</a> is a shading +language designed for use in physically based renderers and in particular +production rendering. By using LLVM instead of the interpreter, it was able to +meet its performance goals (>= C-code) while retaining the benefits of +runtime specialization and a portable high-level language. </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> +</div> -</ul> + + +<!-- *********************************************************************** --> +<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="ARM">ARM Target Improvements</a> +<a name="majorfeatures">Major New Features</a> </div> <div class="doc_text"> -<p>New features of the ARM target include: -</p> + +<p>LLVM 2.8 includes several major new capabilities:</p> <ul> +<li>As mentioned above, <a href="#libc++">libc++</a> and <a + href="#lldb">LLDB</a> are major new additions to the LLVM collective.</li> +<li>LLVM 2.8 now has pretty decent support for debugging optimized code. You + should be able to reliably get debug info for function arguments, assuming + that the value is actually available where you have stopped.</li> +<li>A new 'llvm-diff' tool is available that does a semantic diff of .ll + files.</li> +<li>The <a href="#mc">MC subproject</a> has made major progress in this release. + Direct .o file writing support for darwin/x86[-64] is now reliable and + support for other targets and object file formats are in progress.</li> +</ul> -<li></li> +</div> -</ul> +<!--=========================================================================--> +<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>The <a href="LangRef.html#int_libc">memcpy, memmove, and memset</a> + intrinsics now take address space qualified pointers and a bit to indicate + whether the transfer is "<a href="LangRef.html#volatile">volatile</a>" or not. +</li> +<li>Per-instruction debug info metadata is much faster and uses less memory by + using the new DebugLoc class.</li> +<li>LLVM IR now has a more formalized concept of "<a + href="LangRef.html#trapvalues">trap values</a>", which allow the optimizer + to optimize more aggressively in the presence of undefined behavior, while + still producing predictable results.</li> +<li>LLVM IR now supports two new <a href="LangRef.html#linkage">linkage + types</a> (linker_private_weak and linker_private_weak_def_auto) which map + onto some obscure MachO concepts.</li> +</ul> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="newapis">New Useful APIs</a> +<a name="optimizer">Optimizer Improvements</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> +<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> +<li>As mentioned above, the optimizer now has support for updating debug + information as it goes. A key aspect of this is the new <a + href="SourceLevelDebugging.html#format_common_value">llvm.dbg.value</a> + intrinsic. This intrinsic represents debug info for variables that are + promoted to SSA values (typically by mem2reg or the -scalarrepl passes).</li> + +<li>The JumpThreading pass is now much more aggressive about implied value + relations, allowing it to thread conditions like "a == 4" when a is known to + be 13 in one of the predecessors of a block. It does this in conjunction + with the new LazyValueInfo analysis pass.</li> +<li>The new RegionInfo analysis pass identifies single-entry single-exit regions + in the CFG. You can play with it with the "opt -regions analyze" or + "opt -view-regions" commands.</li> +<li>The loop optimizer has significantly improved strength reduction and analysis + capabilities. Notably it is able to build on the trap value and signed + integer overflow information to optimize <= and >= loops.</li> +<li>The CallGraphSCCPassManager now has some basic support for iterating within + an SCC when a optimizer devirtualizes a function call. This allows inlining + through indirect call sites that are devirtualized by store-load forwarding + and other optimizations.</li> +<li>The new <A href="Passes.html#loweratomic">-loweratomic</a> pass is available + to lower atomic instructions into their non-atomic form. This can be useful + to optimize generic code that expects to run in a single-threaded + environment.</li> </ul> +<!-- +<p>In addition to these features that are done in 2.8, there is preliminary + support in the release for Type Based Alias Analysis + Preliminary work on TBAA but not usable in 2.8. + New CorrelatedValuePropagation pass, not on by default in 2.8 yet. +--> </div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="otherimprovements">Other Improvements and New Features</a> +<a name="mc">MC Level Improvements</a> </div> <div class="doc_text"> -<p>Other miscellaneous features include:</p> +<p> +The LLVM Machine Code (aka MC) subsystem 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.</p> + +<p>The MC subproject has made great leaps in LLVM 2.8. For example, support for + directly writing .o files from LLC (and clang) now works reliably for + darwin/x86[-64] (including inline assembly support) and the integrated + assembler is turned on by default in Clang for these targets. This provides + improved compile times among other things.</p> <ul> -<li></li> +<li>The entire compiler has converted over to using the MCStreamer assembler API + instead of writing out a .s file textually.</li> +<li>The "assembler parser" is far more mature than in 2.7, supporting a full + complement of directives, now supports assembler macros, etc.</li> +<li>The "assembler backend" has been completed, including support for relaxation + relocation processing and all the other things that an assembler does.</li> +<li>The MachO file format support is now fully functional and works.</li> +<li>The MC disassembler now fully supports ARM and Thumb. ARM assembler support + is still in early development though.</li> +<li>The X86 MC assembler now supports the X86 AES and AVX instruction set.</li> +<li>Work on ELF and COFF object files and ARM target support is well underway, + but isn't useful yet in LLVM 2.8. Please contact the llvmdev mailing list + if you're interested in this.</li> </ul> -</div> +<p>For more information, 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> + +</div> <!--=========================================================================--> <div class="doc_subsection"> -<a name="changes">Major Changes and Removed Features</a> +<a name="codegen">Target Independent Code Generator Improvements</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> +<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>.ll file doesn't produce #uses comments anymore, to get them, run a .bc file - through "llvm-dis --show-annotations".</li> -<li>MSIL Backend removed.</li> -<li>ABCD and SSI passes removed.</li> -<li>'Union' LLVM IR feature removed.</li> +<li>The clang/gcc -momit-leaf-frame-pointer argument is now supported.</li> +<li>The clang/gcc -ffunction-sections and -fdata-sections arguments are now + supported on ELF targets (like GCC).</li> +<li>The MachineCSE pass is now tuned and on by default. It eliminates common + subexpressions that are exposed when lowering to machine instructions.</li> +<li>The "local" register allocator was replaced by a new "fast" register + allocator. This new allocator (which is often used at -O0) is substantially + faster and produces better code than the old local register allocator.</li> +<li>A new LLC "-regalloc=default" option is available, which automatically + chooses a register allocator based on the -O optimization level.</li> +<li>The common code generator code was modified to promote illegal argument and + return value vectors to wider ones when possible instead of scalarizing + them. For example, <3 x float> will now pass in one SSE register + instead of 3 on X86. This generates substantially better code since the + rest of the code generator was already expecting this.</li> +<li>The code generator uses a new "COPY" machine instruction. This speeds up + the code generator and eliminates the need for targets to implement the + isMoveInstr hook. Also, the copyRegToReg hook was renamed to copyPhysReg + and simplified.</li> +<li>The code generator now has a "LocalStackSlotPass", which optimizes stack + slot access for targets (like ARM) that have limited stack displacement + addressing.</li> +<li>A new "PeepholeOptimizer" is available, which eliminates sign and zero + extends, and optimizes away compare instructions when the condition result + is available from a previous instruction.</li> +<li>Atomic operations now get legalized into simpler atomic operations if not + natively supported, easing the implementation burden on targets.</li> +<li>We have added two new bottom-up pre-allocation register pressure aware schedulers: +<ol> +<li>The hybrid scheduler schedules aggressively to minimize schedule length when registers are available and avoid overscheduling in high pressure situations.</li> +<li>The instruction-level-parallelism scheduler schedules for maximum ILP when registers are available and avoid overscheduling in high pressure situations.</li> +</ol></li> +<li>The tblgen type inference algorithm was rewritten to be more consistent and + diagnose more target bugs. If you have an out-of-tree backend, you may + find that it finds bugs in your target description. This support also + allows limited support for writing patterns for instructions that return + multiple results (e.g. a virtual register and a flag result). The + 'parallel' modifier in tblgen was removed, you should use the new support + for multiple results instead.</li> +<li>A new (experimental) "-rendermf" pass is available which renders a + MachineFunction into HTML, showing live ranges and other useful + details.</li> +<li>The new SubRegIndex tablegen class allows subregisters to be indexed + symbolically instead of numerically. If your target uses subregisters you + will need to adapt to use SubRegIndex when you upgrade to 2.8.</li> +<!-- SplitKit --> + +<li>The -fast-isel instruction selection path (used at -O0 on X86) was rewritten + to work bottom-up on basic blocks instead of top down. This makes it + slightly faster (because the MachineDCE pass is not needed any longer) and + allows it to generate better code in some cases.</li> + </ul> +</div> -<p>In addition, many APIs have changed in this release. Some of the major LLVM -API changes are:</p> +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="x86">X86-32 and X86-64 Target Improvements</a> +</div> + +<div class="doc_text"> +<p>New features and major changes in 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 targeting CPUs that don't support SSE.</li> + +<li>The X86 backend now uses a SSEDomainFix pass to optimize SSE operations. On + Nehalem ("Core i7") and newer CPUs there is a 2 cycle latency penalty on + using a register in a different domain than where it was defined. This pass + optimizes away these stalls.</li> + +<li>The X86 backend now promotes 16-bit integer operations to 32-bits when + possible. This avoids 0x66 prefixes, which are slow on some + microarchitectures and bloat the code on all of them.</li> + +<li>The X86 backend now supports the Microsoft "thiscall" calling convention, + and a <a href="LangRef.html#callingconv">calling convention</a> to support + <a href="#GHC">ghc</a>.</li> + +<li>The X86 backend supports a new "llvm.x86.int" intrinsic, which maps onto + the X86 "int $42" and "int3" instructions.</li> + +<li>At the IR level, the <2 x float> datatype is now promoted and passed + around as a <4 x float> instead of being passed and returned as an MMX + vector. If you have a frontend that uses this, please pass and return a + <2 x i32> instead (using bitcasts).</li> + +<li>When printing .s files in verbose assembly mode (the default for clang -S), + the X86 backend now decodes X86 shuffle instructions and prints human + readable comments after the most inscrutable of them, e.g.: + +<pre> + insertps $113, %xmm3, %xmm0 <i># xmm0 = zero,xmm0[1,2],xmm3[1]</i> + unpcklps %xmm1, %xmm0 <i># xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]</i> + pshufd $1, %xmm1, %xmm1 <i># xmm1 = xmm1[1,0,0,0]</i> +</pre> +</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>The ARM backend now optimizes tail calls into jumps.</li> +<li>Scheduling is improved through the new list-hybrid scheduler as well + as through better modeling of structural hazards.</li> +<li><a href="LangRef.html#int_fp16">Half float</a> instructions are now + supported.</li> +<li>NEON support has been improved to model instructions which operate onto + multiple consecutive registers more aggressively. This avoids lots of + extraneous register copies.</li> +<li>The ARM backend now uses a new "ARMGlobalMerge" pass, which merges several + global variables into one, saving extra address computation (all the global + variables can be accessed via same base address) and potentially reducing + register pressure.</li> + +<li>The ARM has received many minor improvements and tweaks which lead to +substantially better performance in a wide range of different scenarios.</li> + +<li>The ARM NEON intrinsics have been substantially reworked to reduce + redundancy and improve code generation. Some of the major changes are: + <ol> + <li> + All of the NEON load and store intrinsics (llvm.arm.neon.vld* and + llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes + of the memory being accessed. + </li> + <li> + The llvm.arm.neon.vaba intrinsic (vector absolute difference and + accumulate) has been removed. This operation is now represented using + the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a + vector add. + </li> + <li> + The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening + vector absolute difference with and without accumulation) have been removed. + They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute + difference) followed by a vector zero-extend operation, and for vabal, + a vector add. + </li> + <li> + The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic + are now replaced by vector truncate operations. + </li> + <li> + The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been + removed. They are now represented as vector sign-extend (vmovls) and + zero-extend (vmovlu) operations. + </li> + <li> + The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and + llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have + been removed. They are replaced by vector add and vector subtract operations + where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either + sign-extended or zero-extended. + </li> + <li> + The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and + llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without + accumulation and subtraction) have been removed. These operations are now + represented as vector multiplications where the operands are either + sign-extended or zero-extended, followed by a vector add for vmlal or a + vector subtract for vmlsl. Note that the polynomial vector multiply + intrinsic, llvm.arm.neon.vmullp, remains unchanged. + </li> + </ol> +</li> -<!-- *********************************************************************** --> -<div class="doc_section"> - <a name="portability">Portability and Supported Platforms</a> +</ul> +</div> + + +<!--=========================================================================--> +<div class="doc_subsection"> +<a name="changes">Major Changes and Removed Features</a> </div> -<!-- *********************************************************************** --> <div class="doc_text"> -<p>LLVM is known to work on the following platforms:</p> +<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>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> +<li>The build configuration machinery changed the output directory names. It + wasn't clear to many people that a "Release-Asserts" build was a release build + without asserts. To make this more clear, "Release" does not include + assertions and "Release+Asserts" does (likewise, "Debug" and + "Debug+Asserts").</li> +<li>The MSIL Backend was removed, it was unsupported and broken.</li> +<li>The ABCD, SSI, and SCCVN passes were removed. These were not fully + functional and their behavior has been or will be subsumed by the + LazyValueInfo pass.</li> +<li>The LLVM IR 'Union' feature was removed. While this is a desirable feature + for LLVM IR to support, the existing implementation was half baked and + barely useful. We'd really like anyone interested to resurrect the work and + finish it for a future release.</li> +<li>If you're used to reading .ll files, you'll probably notice that .ll file + dumps don't produce #uses comments anymore. To get them, run a .bc file + through "llvm-dis --show-annotations".</li> +<li>Target triples are now stored in a normalized form, and all inputs from + humans are expected to be normalized by Triple::normalize before being + stored in a module triple or passed to another library.</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> + + +<p>In addition, many APIs have changed in this release. Some of the major LLVM +API changes are:</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, please use the <tt>CallSite</tt> class 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.* intrinsics take an extra + parameter now ("i1 isVolatile"), totaling 5 parameters, and the pointer + operands are now address-space qualified. + If you were creating these intrinsic calls and prototypes yourself (as opposed + to using Intrinsic::getDeclaration), you can use + UpgradeIntrinsicFunction/UpgradeIntrinsicCall to be portable across releases. +</li> +<li> + SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode. + Change your code to use + SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)). +</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> +<li> + The constructor for the Triple class no longer tries to understand odd triple + specifications. Frontends should ensure that they only pass valid triples to + LLVM. The Triple::normalize utility method has been added to help front-ends + deal with funky triples. +</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> + <li>VISIBILITY_HIDDEN -> LLVM_LIBRARY_VISIBILITY</li> + </ul> +</li> + +</ul> </div> + <!-- *********************************************************************** --> <div class="doc_section"> <a name="knownproblems">Known Problems</a> @@ -559,18 +1039,6 @@ 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> <!-- ======================================================================= --> @@ -588,10 +1056,10 @@ components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p> <ul> -<li>The 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> +<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PIC16, SystemZ + and XCore backends are experimental.</li> +<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets + other than darwin-i386 and darwin-x86_64.</li> </ul> </div> @@ -699,6 +1167,9 @@ appropriate nops inserted to ensure restartability.</li> <div class="doc_text"> +<p>The C backend has numerous problems and is not being actively maintained. +Depending on it for anything serious is not advised.</p> + <ul> <li><a href="http://llvm.org/PR802">The C backend has only basic support for inline assembly code</a>.</li> @@ -714,69 +1185,28 @@ appropriate nops inserted to ensure restartability.</li> <!-- ======================================================================= --> <div class="doc_subsection"> - <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a> + <a name="llvm-gcc">Known problems with the llvm-gcc 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> +<p>llvm-gcc is generally very stable for the C family of languages. 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> + +<p>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. Note that llvm-gcc is missing major + Fortran performance work in the frontend and library that went into GCC after + 4.2. If you are interested in Fortran, we recommend that you consider using + <a href="#dragonegg">dragonegg</a> instead.</p> + +<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being +actively maintained. If you are interested in Ada, we recommend that you +consider using <a href="#dragonegg">dragonegg</a> instead.</p> </div> <!-- *********************************************************************** --> |