diff options
| author | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
|---|---|---|
| committer | mike-m <mikem.llvm@gmail.com> | 2010-05-06 23:45:43 +0000 |
| commit | 68cb31901c590cabceee6e6356d62c84142114cb (patch) | |
| tree | 6444bddc975b662fbe47d63cd98a7b776a407c1a /docs/ReleaseNotes.html | |
| parent | c26ae5ab7e2d65b67c97524e66f50ce86445dec7 (diff) | |
Overhauled llvm/clang docs builds. Closes PR6613.
NOTE: 2nd part changeset for cfe trunk to follow.
*** PRE-PATCH ISSUES ADDRESSED
- clang api docs fail build from objdir
- clang/llvm api docs collide in install PREFIX/
- clang/llvm main docs collide in install
- clang/llvm main docs have full of hard coded destination
assumptions and make use of absolute root in static html files;
namely CommandGuide tools hard codes a website destination
for cross references and some html cross references assume
website root paths
*** IMPROVEMENTS
- bumped Doxygen from 1.4.x -> 1.6.3
- splits llvm/clang docs into 'main' and 'api' (doxygen) build trees
- provide consistent, reliable doc builds for both main+api docs
- support buid vs. install vs. website intentions
- support objdir builds
- document targets with 'make help'
- correct clean and uninstall operations
- use recursive dir delete only where absolutely necessary
- added call function fn.RMRF which safeguards against botched 'rm -rf';
if any target (or any variable is evaluated) which attempts
to remove any dirs which match a hard-coded 'safelist', a verbose
error will be printed and make will error-stop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103213 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/ReleaseNotes.html')
| -rw-r--r-- | docs/ReleaseNotes.html | 1237 |
1 files changed, 0 insertions, 1237 deletions
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html deleted file mode 100644 index 94e5c7b398..0000000000 --- a/docs/ReleaseNotes.html +++ /dev/null @@ -1,1237 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> -<html> -<head> - <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> - <link rel="stylesheet" href="llvm.css" type="text/css"> - <title>LLVM 2.8 Release Notes</title> -</head> -<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 2.7 time-frame, the Clang team has made many improvements:</p> - -<ul> - -<li>C++ Support: Clang is now capable of self-hosting! While still -alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang, -and C++ is now enabled by default. See the <a -href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility -page</a> for common C++ migration issues.</li> - -<li>Objective-C: Clang now includes experimental support for an updated -Objective-C ABI on non-Darwin platforms. This includes support for non-fragile -instance variables and accelerated proxies, as well as greater potential for -future optimisations. The new ABI is used when compiling with the --fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these -options may be mixed with code compiled with GCC or clang using the old GNU ABI, -but requires the libobjc2 runtime from the GNUstep project.</li> - -<li>New warnings: Clang contains a number of new warnings, including -control-flow warnings (unreachable code, missing return statements in a -non-<code>void</code> function, etc.), sign-comparison warnings, and improved -format-string warnings.</li> - -<li>CIndex API and Python bindings: Clang now includes a C API as part of the -CIndex library. Although we may make some changes to the API in the future, it -is intended to be stable and has been designed for use by external projects. See -the Clang -doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a> -documentation for more details. The CIndex API also includes a preliminary -set of Python bindings.</li> - -<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM -ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now -suitable for use as a beta quality ARM compiler.</li> - -</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 2.7 time-frame, the analyzer core has made several major and - minor improvements, including better support for tracking the fields of - structures, initial support (not enabled by default yet) for doing - interprocedural (cross-function) analysis, and new checks have been added. -</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 2.7, VMKit has shifted to a great framework for writing -virtual machines. VMKit now offers precise and efficient garbage collection with -multi-threading support, thanks to the MMTk memory management toolkit, as well -as just in time and ahead of time compilation with LLVM. The major changes in -VMKit 0.27 are:</p> - -<ul> - -<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors. - The first collector to be ported is the MarkSweep collector, which is precise, - and drastically improves the performance of VMKit.</li> -<li>Line number information in the JVM: by using the debug metadata of LLVM, the - JVM now supports precise line number information, useful when printing a stack - trace.</li> -<li>Interface calls in the JVM: we implemented a variant of the Interface Method - Table technique for interface calls in the JVM. -</li> - -</ul> -</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 2.7: compiler_rt now -supports ARM targets.</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> -DragonEgg is a new project which is seeing its first release with llvm-2.7. -</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>2.7 includes major parts of the work required by the new MC Project. A few - targets have been refactored to support it, and work is underway to support a - native assembler in LLVM. This work is not complete in LLVM 2.7, but it has - made substantially more progress on LLVM mainline.</p> - -<p>One minor example of what MC can do is to transcode an AT&T syntax - X86 .s file into intel syntax. You can do this with something like:</p> -<pre> - llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s -</pre> - -</div> - - -<!-- *********************************************************************** --> -<div class="doc_section"> - <a name="externalproj">External Open Source Projects Using LLVM 2.7</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 2.7.</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<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>Pure versions 0.43 and later have been tested and are known to work with -LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p> - -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="RoadsendPHP">Roadsend PHP</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open -source implementation of the PHP programming -language that uses LLVM for its optimizer, JIT and static compiler. This is a -reimplementation of an earlier project that is now based on LLVM. -</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="UnladenSwallow">Unladen Swallow</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a -branch of <a href="http://python.org/">Python</a> intended to be fully -compatible and significantly faster. It uses LLVM's optimization passes and JIT -compiler. -</p> -</div> - -<!--=========================================================================--> -<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>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="safecode">SAFECode Compiler</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C -compiler built using LLVM. It takes standard, unannotated C code, analyzes the -code to ensure that memory accesses and array indexing operations are safe, and -instruments the code with run-time checks when safety cannot be proven -statically. -</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="icedtea">IcedTea Java Virtual Machine Implementation</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a -harness to build OpenJDK using only free software build tools and to provide -replacements for the not-yet free parts of OpenJDK. One of the extensions that -IcedTea provides is a new JIT compiler named <a -href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM -to provide native code generation without introducing processor-dependent -code. -</p> -<p>Icedtea6 1.8 and later have been tested and are known to work with -LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well). -</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="llvm-lua">LLVM-Lua</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM - to add JIT and static compiling support to the Lua VM. Lua -bytecode is analyzed to remove type checks, then LLVM is used to compile the -bytecode down to machine code. -</p> -<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7. -</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="MacRuby">MacRuby</a> -</div> - -<div class="doc_text"> -<p> -<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on -core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for -optimization passes, JIT compilation and exception handling. It also allows -static (ahead-of-time) compilation of Ruby code straight to machine code. -</p> -<p>The upcoming MacRuby 0.6 release works with LLVM 2.7. -</p> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="GHC">Glasgow Haskell Compiler (GHC)</a> -</div> - -<div class="doc_text"> -<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> - -<p>In addition to the existing C and native code generators, GHC 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.</p> - -</div> - - -<!-- *********************************************************************** --> -<div class="doc_section"> - <a name="whatsnew">What's New in LLVM 2.7?</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 2.6 and 2.7, a number of -organization changes have happened: -</p> - -<ul> -<li>LLVM has a new <a href="http://llvm.org/Logo.html">official logo</a>!</li> - -<li>Ted Kremenek and Doug Gregor have stepped forward as <a - href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the - Clang static analyzer and the Clang frontend, respectively.</li> - -<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at - <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way - to learn about new LLVM-related features as they are implemented. Several - features in this release are already explained on the blog.</li> - -<li>The LLVM web pages are now checked into the SVN server, in the "www", - "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a - largely inaccessible old CVS server.</li> - -<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much - faster) server. It is still graciously hosted at the University of Illinois - of Urbana Champaign.</li> -</ul> -</div> - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="majorfeatures">Major New Features</a> -</div> - -<div class="doc_text"> - -<p>LLVM 2.7 includes several major new capabilities:</p> - -<ul> -<li>2.7 includes initial support for the <a - href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target. - MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li> - -<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature - supports many different use cases, including allowing front-end authors to - encode source level information into LLVM IR, which is consumed by later - language-specific passes. This is a great way to do high-level optimizations - like devirtualization, type-based alias analysis, etc. See the <a - href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html"> - Extensible Metadata Blog Post</a> for more information.</li> - -<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a> -in a completely new way, built on extensible metadata. The new implementation -is much more memory efficient and paves the way for improvements to optimized -code debugging experience.</li> - -<li>2.7 now directly supports taking the address of a label and doing an - indirect branch through a pointer. This is particularly useful for - interpreter loops, and is used to implement the GCC "address of label" - extension. For more information, see the <a -href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html"> -Address of Label and Indirect Branches in LLVM IR Blog Post</a>. - -<li>2.7 is the first release to start supporting APIs for assembling and - disassembling target machine code. These APIs are useful for a variety of - low level clients, and are surfaced in the new "enhanced disassembly" API. - For more information see the <a - href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86 - Disassembler Blog Post</a> for more information.</li> - -<li>2.7 includes major parts of the work required by the new MC Project, - see the <a href="#mc">MC update above</a> for more information.</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 IR now supports a 16-bit "half float" data type through <a - href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li> -<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function - attributes</a>: inlinehint and alignstack(n). The former is a hint to the - optimizer that a function was declared 'inline' and thus the inliner should - weight it higher when considering inlining it. The later - indicates to the code generator that the function diverges from the platform - ABI on stack alignment.</li> -<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic - allows the optimizer to infer the sizes of memory objects in some cases. - This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt> - extension.</li> -<li>LLVM IR now supports marking load and store instructions with <a - href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new - metadata feature). This hint encourages the code - generator to generate non-temporal accesses when possible, which are useful - for code that is carefully managing cache behavior. Currently, only the - X86 backend provides target support for this feature.</li> - -<li>LLVM 2.7 has pre-alpha support for <a - href="LangRef.html#t_union">unions in LLVM IR</a>. - Unfortunately, this support is not really usable in 2.7, so if you're - interested in pushing it forward, please help contribute to LLVM mainline.</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>The inliner now merges arrays stack objects in different callees when - inlining multiple call sites into one function. This reduces the stack size - of the resultant function.</li> -<li>The -basicaa alias analysis pass (which is the default) has been improved to - be less dependent on "type safe" pointers. It can now look through bitcasts - and other constructs more aggressively, allowing better load/store - optimization.</li> -<li>The load elimination optimization in the GVN Pass [<a -href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro - blog post</a>] has been substantially improved to be more aggressive about - partial redundancy elimination and do more aggressive phi translation. Please - see the <a - href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html"> - Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation - Blog Post</a> for more details.</li> -<li>The module <a href="LangRef.html#datalayout">target data string</a> now - includes a notion of 'native' integer data types for the target. This - helps mid-level optimizations avoid promoting complex sequences of - operations to data types that are not natively supported (e.g. converting - i32 operations to i64 on 32-bit chips).</li> -<li>The mid-level optimizer is now conservative when operating on a module with - no target data. Previously, it would default to SparcV9 settings, which is - not what most people expected.</li> -<li>Jump threading is now much more aggressive at simplifying correlated - conditionals and threading blocks with otherwise complex logic. It has - subsumed the old "Conditional Propagation" pass, and -condprop has been - removed from LLVM 2.7.</li> -<li>The -instcombine pass has been refactored from being one huge file to being - a library of its own. Internally, it uses a customized IRBuilder to clean - it up and simplify it.</li> - -<li>The optimal edge profiling pass is reliable and much more complete than in - 2.6. It can be used with the llvm-prof tool but isn't wired up to the - llvm-gcc and clang command line options yet.</li> - -<li>A new experimental alias analysis implementation, -scev-aa, has been added. - It uses LLVM's Scalar Evolution implementation to do symbolic analysis of - pointer offset expressions to disambiguate pointers. It can catch a few - cases that basicaa cannot, particularly in complex loop nests.</li> - -<li>The default pass ordering has been tweaked for improved optimization - effectiveness.</li> - -</ul> - -</div> - - -<!--=========================================================================--> -<div class="doc_subsection"> -<a name="executionengine">Interpreter and JIT Improvements</a> -</div> - -<div class="doc_text"> - -<ul> -<li>The JIT now supports generating debug information and is compatible with -the new GDB 7.0 (and later) interfaces for registering dynamically generated -debug info.</li> - -<li>The JIT now <a href="http://llvm.org/PR5184">defaults -to compiling eagerly</a> to avoid a race condition in the lazy JIT. -Clients that still want the lazy JIT can switch it on by calling -<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li> - -<li>It is now possible to create more than one JIT instance in the same process. -These JITs can generate machine code in parallel, -although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you -still have to obey the other threading restrictions</a>.</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>The 'llc -asm-verbose' option (which is now the default) has been enhanced - to emit many useful comments to .s files indicating information about spill - slots and loop nest structure. This should make it much easier to read and - understand assembly files. This is wired up in llvm-gcc and clang to - the <tt>-fverbose-asm</tt> option.</li> - -<li>New LSR with "full strength reduction" mode, which can reduce address - register pressure in loops where address generation is important.</li> - -<li>A new codegen level Common Subexpression Elimination pass (MachineCSE) - is available and enabled by default. It catches redundancies exposed by - lowering.</li> -<li>A new pre-register-allocation tail duplication pass is available and enabled - by default, it can substantially improve branch prediction quality in some - cases.</li> -<li>A new sign and zero extension optimization pass (OptimizeExtsPass) - is available and enabled by default. This pass can takes advantage - architecture features like x86-64 implicit zero extension behavior and - sub-registers.</li> -<li>The code generator now supports a mode where it attempts to preserve the - order of instructions in the input code. This is important for source that - is hand scheduled and extremely sensitive to scheduling. It is compatible - with the GCC <tt>-fno-schedule-insns</tt> option.</li> -<li>The target-independent code generator now supports generating code with - arbitrary numbers of result values. Returning more values than was - previously supported is handled by returning through a hidden pointer. In - 2.7, only the X86 and XCore targets have adopted support for this - though.</li> -<li>The code generator now supports generating code that follows the - <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling - Convention</a> and ABI.</li> -<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction - selection</a>" phase of the code generator has been largely rewritten for - 2.7. Previously, tblgen spit out tons of C++ code which was compiled and - linked into the target to do the pattern matching, now it emits a much - smaller table which is read by the target-independent code. The primary - advantages of this approach is that the size and compile time of various - targets is much improved. The X86 code generator shrunk by 1.5MB of code, - for example.</li> -<li>Almost the entire code generator has switched to emitting code through the - MC interfaces instead of printing textually to the .s file. This led to a - number of cleanups and speedups. In 2.7, debug an exception handling - information does not go through MC yet.</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 optimizes tails calls much more aggressively for - functions that use the standard C calling convention.</li> -<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector - registers, making the code generator more aggressive in cases where scalars - and vector types are mixed.</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 generates instructions in unified assembly syntax.</li> - -<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This - support differs slightly from the GCC implementation. Please see the - <a -href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html"> - ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for - helpful information if migrating code from GCC to LLVM-GCC.</li> - -<li>The ARM and Thumb code generators now use register scavenging for stack - object address materialization. This allows the use of R3 as a general - purpose register in Thumb1 code, as it was previous reserved for use in - stack address materialization. Secondly, sequential uses of the same - value will now re-use the materialized constant.</li> - -<li>The ARM backend now has good support for ARMv4 targets and has been tested - on StrongARM hardware. Previously, LLVM only supported ARMv4T and - newer chips.</li> - -<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize, - __sync_fetch_and_add, etc.).</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>The optimizer uses the new CodeMetrics class to measure the size of code. - Various passes (like the inliner, loop unswitcher, etc) all use this to make - more accurate estimates of the code size impact of various - optimizations.</li> -<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html"> - llvm/Analysis/InstructionSimplify.h</a> interface is available for doing - symbolic simplification of instructions (e.g. <tt>a+0</tt> -> <tt>a</tt>) - without requiring the instruction to exist. This centralizes a lot of - ad-hoc symbolic manipulation code scattered in various passes.</li> -<li>The optimizer now uses a new <a - href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a> - class which efficiently supports - doing unstructured SSA update operations. This centralized a bunch of code - scattered throughout various passes (e.g. jump threading, lcssa, - loop rotate, etc) for doing this sort of thing. The code generator has a - similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html"> - MachineSSAUpdater</a> class.</li> -<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html"> - llvm/Support/Regex.h</a> header exposes a platform independent regular - expression API. Building on this, the <a - href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports - regular exressions.</li> -<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()". - By default, this stream works the same way as "errs()", but if you pass - <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a - fixed sized circular buffer and the output is printed at the end of the - program's execution. This is helpful if you have a long lived compiler - process and you're interested in seeing snapshots in time.</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>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To - get this, configure LLVM with the --enable-shared option.</li> - -<li>LLVM command line tools now overwrite their output by default. Previously, - they would only do this with -f. This makes them more convenient to use, and - behave more like standard unix tools.</li> - -<li>The opt and llc tools now autodetect whether their input is a .ll or .bc - file, and automatically do the right thing. This means you don't need to - explicitly use the llvm-as tool for most things.</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 2.6, this section lists some "gotchas" that you may run into upgrading -from the previous release.</p> - -<ul> - -<li> -The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier -("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling -profiling ("rsprofiling") passes have all been removed. They were not being -actively maintained and had substantial problems. If you are interested in -these components, you are welcome to ressurect them from SVN, fix the -correctness problems, and resubmit them to mainline.</li> - -<li>LLVM now defaults to building most libraries with RTTI turned off, providing -a code size reduction. Packagers who are interested in building LLVM to support -plugins that require RTTI information should build with "make REQUIRE_RTTI=1" -and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a> -document.</li> - -<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even -if you have it installed. This makes it more likely that an LLVM built on one -system will work when copied to a similar system. To use <tt>libffi</tt>, -configure with <tt>--enable-libffi</tt>.</li> - -<li>Debug information uses a completely different representation, an LLVM 2.6 -.bc file should work with LLVM 2.7, but debug info won't come forward.</li> - -<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed, - along with LowerAllocations pass. Now you should just use a call to the - malloc and free functions in libc. These calls are optimized as well as - the old instructions were.</li> -</ul> - -<p>In addition, many APIs have changed in this release. Some of the major LLVM -API changes are:</p> - -<ul> - -<li>The <tt>add</tt>, <tt>sub</tt>, and <tt>mul</tt> instructions no longer -support floating-point operands. The <tt>fadd</tt>, <tt>fsub</tt>, and -<tt>fmul</tt> instructions should be used for this purpose instead.</li> - -</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> -</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. The MachO writer is experimental, and - works much better in mainline SVN.</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>The X86 backend generates inefficient floating point code when configured - to generate code for systems that don't have SSE2.</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> - -<!-- *********************************************************************** --> - -<hr> -<address> - <a href="http://jigsaw.w3.org/css-validator/check/referer"><img - src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> - <a href="http://validator.w3.org/check/referer"><img - src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> - - <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br> - Last modified: $Date$ -</address> - -</body> -</html> |