<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.7 Release Notes</title>
+ <title>LLVM 2.9 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.7 Release Notes</div>
+<h1 class="doc_title">LLVM 2.9 Release Notes</h1>
<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 2.7</a></li>
- <li><a href="#whatsnew">What's New in LLVM 2.7?</a></li>
+ <li><a href="#externalproj">External Projects Using LLVM 2.9</a></li>
+ <li><a href="#whatsnew">What's New in LLVM 2.9?</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>
+ <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
+<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.9
release.<br>
You may prefer the
-<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.7
-Release Notes</a>.</h1>-->
+<a href="http://llvm.org/releases/2.8/docs/ReleaseNotes.html">LLVM 2.8
+Release Notes</a>.</h1>
+ -->
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="intro">Introduction</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This document contains the release notes for the LLVM Compiler
-Infrastructure, release 2.7. Here we describe the status of LLVM, including
+Infrastructure, release 2.9. 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>
<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 2.7:
+<!-- Features that need text if they're finished for 3.1:
+ ARM EHABI
combiner-aa?
strong phi elim
- llvm.dbg.value: variable debug info for optimized code
loop dependence analysis
+ CorrelatedValuePropagation
+ lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
-->
-
- <!-- for announcement email:
- Logo web page.
- llvm devmtg
- compiler_rt
- KLEE web page at klee.llvm.org
- Many new papers added to /pubs/
- Mention gcc plugin.
- -->
-
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="subproj">Sub-project Status Update</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
-The LLVM 2.7 distribution currently consists of code from the core LLVM
+The LLVM 2.9 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
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
-</div>
+</h2>
<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><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, Objective-C, C++ and Objective-C++ on x86
+(32- and 64-bit), and for darwin/arm targets.</p>
+
+<p>In the LLVM 2.9 time-frame, the Clang team has made many improvements in C,
+C++ and Objective-C support. C++ support is now generally rock solid, has
+been exercised on a broad variety of code, and has several new <a
+href="http://clang.llvm.org/cxx_status.html#cxx0x">C++'0x features</a>
+implemented (such as rvalue references and variadic templates). LLVM 2.9 has
+also brought in a large range of bug fixes and minor features (e.g. __label__
+support), and is much more compatible with the Linux Kernel.</p>
+
+<p>If Clang rejects your code but another compiler accepts it, please take a
+look at the <a href="http://clang.llvm.org/compatibility.html">language
+compatibility</a> guide to make sure this is not intentional or a known issue.
</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
-</div>
+<h2>
+<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
+</h2>
<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
+<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
+optimizers and code generators with LLVM's.
+Currently it requires a patched version of gcc-4.5.
+The plugin can target the x86-32 and x86-64 processor families and has been
+used successfully on the Darwin, FreeBSD and Linux platforms.
+The Ada, C, C++ and Fortran languages work well.
+The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is
+not known whether the compiled code actually works or not!
+</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>
-
+The 2.9 release has the following notable changes:
<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>
-
+<li>The plugin is much more stable when compiling Fortran.</li>
+<li>Inline assembly where an asm output is tied to an input of a different size
+is now supported in many more cases.</li>
+<li>Basic support for the __float128 type was added. It is now possible to
+generate LLVM IR from programs using __float128 but code generation does not
+work yet.</li>
+<li>Compiling Java programs no longer systematically crashes the plugin.</li>
</ul>
-</div>
+</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
-</div>
+</h2>
<div class="doc_text">
<p>
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>
+<p>In the LLVM 2.9 timeframe, compiler_rt has had several minor changes for
+ better ARM support, and a fairly major license change. All of the code in the
+ compiler-rt project is now <a href="DeveloperPolicy.html#license">dual
+ licensed</a> under MIT and UIUC license, which allows you to use compiler-rt
+ in applications without the binary copyright reproduction clause. If you
+ prefer the LLVM/UIUC license, you are free to continue using it under that
+ license as well.</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
-</div>
+<h2>
+<a name="lldb">LLDB: Low Level Debugger</a>
+</h2>
<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).
-</p>
+LLDB is has advanced by leaps and bounds in the 2.9 timeframe. It is
+dramatically more stable and useful, and includes both a new <a
+href="http://lldb.llvm.org/tutorial.html">tutorial</a> and a <a
+href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with
+GDB</a>.</p>
+</div>
+
+<!--=========================================================================-->
+<h2>
+<a name="libc++">libc++: C++ Standard Library</a>
+</h2>
+
+<div class="doc_text">
+<p>
+<a href="http://libcxx.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>
+In the LLVM 2.9 timeframe, libc++ has had numerous bugs fixed, and is now being
+co-developed with Clang's C++'0x mode.</p>
+
<p>
-DragonEgg is a new project which is seeing its first release with llvm-2.7.
+Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
+ licensed</a> under the MIT and UIUC license, allowing it to be used more
+ permissively.
</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="mc">llvm-mc: Machine Code Toolkit</a>
-</div>
+<h2>
+<a name="LLBrowse">LLBrowse: IR Browser</a>
+</h2>
<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://llvm.org/svn/llvm-project/llbrowse/trunk/doc/LLBrowse.html">
+ LLBrowse</a> is an interactive viewer for LLVM modules. It can load any LLVM
+ module and displays its contents as an expandable tree view, facilitating an
+ easy way to inspect types, functions, global variables, or metadata nodes. It
+ is fully cross-platform, being based on the popular wxWidgets GUI toolkit.
</p>
+</div>
-<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 you has
- made substantially more progress on LLVM mainline.</p>
+<!--=========================================================================-->
+<h2>
+<a name="vmkit">VMKit</a>
+</h2>
-<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 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 2.9, VMKit now supports generational
+ garbage collectors. The garbage collectors are provided by the MMTk framework,
+ and VMKit can be configured to use one of the numerous implemented collectors
+ of MMTk.
+</p>
+</div>
+
+
+<!--=========================================================================-->
+<!--
+<h2>
+<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
+</h2>
-</div>
+<div class="doc_text">
+<p>
+<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>UPDATE!</p>
+</div>-->
<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
-</div>
+<h1>
+ <a name="externalproj">External Open Source Projects Using LLVM 2.9</a>
+</h1>
<!-- *********************************************************************** -->
<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>
+ projects that have already been updated to work with LLVM 2.9.</p>
</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>
+<h2>Crack Programming Language</h2>
<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>
+<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.</p>
</div>
-
+
+
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="UnladenSwallow">Unladen Swallow</a>
-</div>
-
+<h2>TTA-based Codesign Environment (TCE)</h2>
+
<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>
+<p>TCE 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 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="tce">TTA-based Codesign Environment (TCE)</a>
-</div>
+
+<!--=========================================================================-->
+<h2>PinaVM</h2>
+
<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>
-
+<p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open
+source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many
+other front-ends, PinaVM actually executes the elaboration of the
+program analyzed using LLVM's JIT infrastructure. It later enriches the
+bitcode with SystemC-specific information.</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="safecode">SAFECode Compiler</a>
-</div>
-
+<h2>Pure</h2>
+
<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>
+<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. The interpreter uses LLVM as a backend to JIT-compile Pure
+ programs to fast native code. 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 interface to C and other
+ programming languages (including the ability to load LLVM bitcode
+ modules, and inline C, C++, Fortran and Faust code in Pure programs if
+ the corresponding LLVM-enabled compilers are installed).</p>
+
+<p>Pure version 0.47 has been tested and is known to work with LLVM 2.9
+ (and continues to work with older LLVM releases >= 2.5).</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
-</div>
+<h2 id="icedtea">IcedTea Java Virtual Machine Implementation</h2>
<div class="doc_text">
<p>
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>
+
+<p> OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested
+and are known to work with LLVM 2.9 (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>
+<h2>Glasgow Haskell Compiler (GHC)</h2>
+
+<div class="doc_text">
+<p>GHC 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 7.0 now
+supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p>
</div>
+<!--=========================================================================-->
+<h2>Polly - Polyhedral optimizations for LLVM</h2>
+
<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>
+<p>Polly is a project that aims to provide advanced memory access optimizations
+to better take advantage of SIMD units, cache hierarchies, multiple cores or
+even vector accelerators for LLVM. Built around an abstract mathematical
+description based on Z-polyhedra, it provides the infrastructure to develop
+advanced optimizations in LLVM and to connect complex external optimizers. In
+its first year of existence Polly already provides an exact value-based
+dependency analysis as well as basic SIMD and OpenMP code generation support.
+Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality
+and parallelism.</p>
+</div>
+
+<!--=========================================================================-->
+<h2>Rubinius</h2>
+
+<div class="doc_text">
+ <p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
+ for running Ruby code which strives to write as much of the implementation in
+ Ruby as possible. Combined with a bytecode interpreting VM, it uses LLVM to
+ optimize and compile ruby code down to machine code. Techniques such as type
+ feedback, method inlining, and deoptimization are all used to remove dynamism
+ from ruby execution and increase performance.</p>
</div>
+
<!--=========================================================================-->
<div class="doc_subsection">
-<a name="MacRuby">MacRuby</a>
+<a name="FAUST">FAUST Real-Time Audio Signal Processing Language</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>
+<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 2.7-2.9.</p>
-
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="whatsnew">What's New in LLVM 2.7?</a>
</div>
+
+<!-- *********************************************************************** -->
+<h1>
+ <a name="whatsnew">What's New in LLVM 2.9?</a>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="orgchanges">LLVM Community Changes</a>
-</div>
+<h2>
+<a name="majorfeatures">Major New Features</a>
+</h2>
<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>
+<p>LLVM 2.9 includes several major new capabilities:</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>
+
+<li>Type Based Alias Analysis (TBAA) is now implemented and turned on by default
+ in Clang. This allows substantially better load/store optimization in some
+ cases. TBAA can be disabled by passing -fno-strict-aliasing.
+</li>
-<div class="doc_text">
+<li>This release has seen a continued focus on quality of debug information.
+ LLVM now generates much higher fidelity debug information, particularly when
+ debugging optimized code.</li>
-<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>
+<li>Inline assembly now supports multiple alternative constraints.</li>
+<li>A new backend for the NVIDIA PTX virtual ISA (used to target its GPUs) is
+ under rapid development. It is not generally useful in 2.9, but is making
+ rapid progress.</li>
+
</ul>
-
+
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="coreimprovements">LLVM IR and Core Improvements</a>
-</div>
+</h2>
<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>
-
+<li>The <a href="LangRef.html#bitwiseops">udiv, ashr, lshr, and shl</a>
+ instructions now have support exact and nuw/nsw bits to indicate that they
+ don't overflow or shift out bits. This is useful for optimization of <a
+ href="http://llvm.org/PR8862">pointer differences</a> and other cases.</li>
+
+<li>LLVM IR now supports the <a href="LangRef.html#globalvars">unnamed_addr</a>
+ attribute to indicate that constant global variables with identical
+ initializers can be merged. This fixed <a href="http://llvm.org/PR8927">an
+ issue</a> where LLVM would incorrectly merge two globals which were supposed
+ to have distinct addresses.</li>
+
+<li>The new <a href="LangRef.html#fnattrs">hotpatch attribute</a> has been added
+ to allow runtime patching of functions.</li>
</ul>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="optimizer">Optimizer Improvements</a>
-</div>
+</h2>
<div class="doc_text">
release includes a few major enhancements and additions to the optimizers:</p>
<ul>
+<li>Link Time Optimization (LTO) has been improved to use MC for parsing inline
+ assembly and now can build large programs like Firefox 4 on both Mac OS X and
+ Linux.</li>
+
+<li>The new -loop-idiom pass recognizes memset/memcpy loops (and memset_pattern
+ on darwin), turning them into library calls, which are typically better
+ optimized than inline code. If you are building a libc and notice that your
+ memcpy and memset functions are compiled into infinite recursion, please build
+ with -ffreestanding or -fno-builtin to disable this pass.</li>
+
+<li>A new -early-cse pass does a fast pass over functions to fold constants,
+ simplify expressions, perform simple dead store elimination, and perform
+ common subexpression elimination. It does a good job at catching some of the
+ trivial redundancies that exist in unoptimized code, making later passes more
+ effective.</li>
+
+<li>A new -loop-instsimplify pass is used to clean up loop bodies in the loop
+ optimizer.</li>
+
+<li>The new TargetLibraryInfo interface allows mid-level optimizations to know
+ whether the current target's runtime library has certain functions. For
+ example, the optimizer can now transform integer-only printf calls to call
+ iprintf, allowing reduced code size for embedded C libraries (e.g. newlib).
+</li>
+
+<li>LLVM has a new <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a>
+ infrastructure for region-based optimizations.</li>
+
+<li>Several optimizer passes have been substantially sped up:
+ GVN is much faster on functions with deep dominator trees and lots of basic
+ blocks. The dominator tree and dominance frontier passes are much faster to
+ compute, and preserved by more passes (so they are computed less often). The
+ -scalar-repl pass is also much faster and doesn't use DominanceFrontier.
+</li>
-<li>The inliner reuses 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>
-
+<li>The Dead Store Elimination pass is more aggressive optimizing stores of
+ different types: e.g. a large store following a small one to the same address.
+ The MemCpyOptimizer pass handles several new forms of memcpy elimination.</li>
+
+<li>LLVM now optimizes various idioms for overflow detection into check of the
+ flag register on various CPUs. For example, we now compile:
+
+ <pre>
+ unsigned long t = a+b;
+ if (t < a) ...
+ </pre>
+ into:
+ <pre>
+ addq %rdi, %rbx
+ jno LBB0_2
+ </pre>
+</li>
+
</ul>
</div>
-
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="executionengine">Interpreter and JIT Improvements</a>
-</div>
+<h2>
+<a name="mc">MC Level Improvements</a>
+</h2>
<div class="doc_text">
+<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>
<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>ELF MC support has matured enough for the integrated assembler to be turned
+ on by default in Clang on X86-32 and X86-64 ELF systems.</li>
+
+<li>MC supports and CodeGen uses the <tt>.file</tt> and <tt>.loc</tt> directives
+ for producing line number debug info. This produces more compact line
+ tables and easier to read .s files.</li>
+
+<li>MC supports the <tt>.cfi_*</tt> directives for producing DWARF
+ frame information, but it is still not used by CodeGen by default.</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>
+
+<li>The MC assembler now generates much better diagnostics for common errors,
+ is much faster at matching instructions, is much more bug-compatible with
+ the GAS assembler, and is now generally useful for a broad range of X86
+ assembly.</li>
+
+<li>We now have some basic <a href="CodeGenerator.html#mc">internals
+ documentation</a> for MC.</li>
+
+<li>.td files can now specify assembler aliases directly with the <a
+ href="CodeGenerator.html#na_instparsing">MnemonicAlias and InstAlias</a>
+ tblgen classes.</li>
+
+<li>LLVM now has an experimental format-independent object file manipulation
+ library (lib/Object). It supports both PE/COFF and ELF. The llvm-nm tool has
+ been extended to work with native object files, and the new llvm-objdump tool
+ supports disassembly of object files (but no relocations are displayed yet).
+</li>
+
+<li>Win32 PE-COFF support in the MC assembler has made a lot of progress in the
+ 2.9 timeframe, but is still not generally useful.</li>
</ul>
+<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">
+<h2>
<a name="codegen">Target Independent Code Generator Improvements</a>
-</div>
+</h2>
<div class="doc_text">
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>
+<li>The pre-register-allocation (preRA) instruction scheduler models register
+ pressure much more accurately in some cases. This allows the adoption of more
+ aggressive scheduling heuristics without causing spills to be generated.
+</li>
+
+<li>LiveDebugVariables is a new pass that keeps track of debugging information
+ for user variables that are promoted to registers in optimized builds.</li>
+
+<li>The scheduler now models operand latency and pipeline forwarding.</li>
+
+<li>A major register allocator infrastructure rewrite is underway. It is not on
+ by default for 2.9 and you are not advised to use it, but it has made
+ substantial progress in the 2.9 timeframe:
+ <ul>
+ <li>A new -regalloc=basic "basic" register allocator can be used as a simple
+ fallback when debugging. It uses the new infrastructure.</li>
+ <li>New infrastructure is in place for live range splitting. "SplitKit" can
+ break a live interval into smaller pieces while preserving SSA form, and
+ SpillPlacement can help find the best split points. This is a work in
+ progress so the API is changing quickly.</li>
+ <li>The inline spiller has learned to clean up after live range splitting. It
+ can hoist spills out of loops, and it can eliminate redundant spills.</li>
+ <li>Rematerialization works with live range splitting.</li>
+ <li>The new "greedy" register allocator using live range splitting. This will
+ be the default register allocator in the next LLVM release, but it is not
+ turned on by default in 2.9.</li>
+ </ul>
+</li>
</ul>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="x86">X86-32 and X86-64 Target Improvements</a>
-</div>
+</h2>
<div class="doc_text">
-<p>New features of the X86 target include:
+<p>New features and major changes in 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>
+<li>LLVM 2.9 includes a complete reimplementation of the MMX instruction set.
+ The reimplementation uses a new LLVM IR <a
+ href="LangRef.html#t_x86mmx">x86_mmx</a> type to ensure that MMX operations
+ are <em>only</em> generated from source that uses MMX builtin operations. With
+ this, random types like <2 x i32> are not turned into MMX operations
+ (which can be catastrophic without proper "emms" insertion). Because the X86
+ code generator always generates reliable code, the -disable-mmx flag is now
+ removed.
+</li>
+
+<li>X86 support for FS/GS relative loads and stores using <a
+ href="CodeGenerator.html#x86_memory">address space 256/257</a> works reliably
+ now.</li>
+
+<li>LLVM 2.9 generates much better code in several cases by using adc/sbb to
+ avoid generation of conditional move instructions for conditional increment
+ and other idioms.</li>
+<li>The X86 backend has adopted a new preRA scheduling mode, "list-ilp", to
+ shorten the height of instruction schedules without inducing register spills.
+</li>
+
+<li>The MC assembler supports 3dNow! and 3DNowA instructions.</li>
+
+<li>Several bugs have been fixed for Windows x64 code generator.</li>
</ul>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="ARM">ARM Target Improvements</a>
-</div>
+</h2>
<div class="doc_text">
<p>New features of the ARM target include:
</p>
<ul>
+<li>The ARM backend now has a fast instruction selector, which dramatically
+ improves -O0 compile times.</li>
+<li>The ARM backend has new tuning for Cortex-A8 and Cortex-A9 CPUs.</li>
+<li>The __builtin_prefetch builtin (and llvm.prefetch intrinsic) is compiled
+ into prefetch instructions instead of being discarded.</li>
-<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>
+<li> The ARM backend preRA scheduler now models machine resources at cycle
+ granularity. This allows the scheduler to both accurately model
+ instruction latency and avoid overcommitting functional units.</li>
+<li>Countless ARM microoptimizations have landed in LLVM 2.9.</li>
</ul>
-
-
</div>
-
+
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="newapis">New Useful APIs</a>
-</div>
+<h2>
+<a name="OtherTS">Other Target Specific Improvements</a>
+</h2>
<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>
+<li>MicroBlaze: major updates for aggressive delay slot filler, MC-based
+ assembly printing, assembly instruction parsing, ELF .o file emission, and MC
+ instruction disassembler have landed.</li>
+<li>SPARC: Many improvements, including using the Y registers for
+ multiplications and addition of a simple delay slot filler.</li>
-</div>
+<li>PowerPC: The backend has been largely MC'ized and is ready to support
+ directly writing out mach-o object files. No one seems interested in finishing
+ this final step though.</li>
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="otherimprovements">Other Improvements and New Features</a>
-</div>
+<li>Mips: Improved o32 ABI support, including better varags handling.
+More instructions supported in codegen: madd, msub, rotr, rotrv and clo.
+It also now supports lowering block addresses.</li>
-<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">
+<h2>
<a name="changes">Major Changes and Removed Features</a>
-</div>
+</h2>
<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
+on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
from the previous release.</p>
<ul>
+<li><b>This is the last release to support the llvm-gcc frontend.</b></li>
-<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>
+<li>LLVM has a new <a href="CodingStandards.html#ll_naming">naming
+ convention standard</a>, though the codebase hasn't fully adopted it yet.</li>
+
+<li>The new DIBuilder class provides a simpler interface for front ends to
+ encode debug info in LLVM IR, and has replaced DIFactory.</li>
-<p>In addition, many APIs have changed in this release. Some of the major LLVM
-API changes are:</p>
+<li>LLVM IR and other tools always work on normalized target triples (which have
+ been run through <tt>Triple::normalize</tt>).</li>
-<ul>
-<li>Just about everything has been converted to use raw_ostream instead of
- std::ostream.</li>
-<li>llvm/ADT/iterator.h has been removed, just use <iterator>
- instead.</li>
-<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() << ...);"
- instead.</li>
-<li>The TargetAsmInfo interface was renamed to MCAsmInfo.</li>
-<li><tt>ModuleProvider</tt> has been <a
-href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
-and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
-Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
-replace <tt>getBitcodeModuleProvider</tt> with
-<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
-functions that used to accept <tt>ModuleProvider</tt>. Clients who
-wrote their own <tt>ModuleProvider</tt>s will need to derive from
-<tt>GVMaterializer</tt> instead and use
-<tt>Module::setMaterializer</tt> to attach it to a
-<tt>Module</tt>.</li>
-
-<li><tt>GhostLinkage</tt> has given up the ghost.
-<tt>GlobalValue</tt>s that have not yet been read from their backing
-storage have the same linkage they will have after being read in.
-Clients must replace calls to
-<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
-<tt>GlobalValue::isMaterializable</tt>.</li>
-
-<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
-<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
-<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
-<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
-
-<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
-<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
- booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
-<li>Some header files have been renamed:
-<ul>
- <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
- <tt>llvm/System/AIXDataTypesFix.h</tt></li>
- <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
- <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
- <tt>llvm/Analysis/InlineCost.h</tt></li>
- <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
- <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
-</ul></li>
+<li>The target triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32
+ instead.</li>
+
+<li>The PointerTracking pass has been removed from mainline, and moved to The
+ ClamAV project (its only client).</li>
+
+<li>The LoopIndexSplit, LiveValues, SimplifyHalfPowrLibCalls, GEPSplitter, and
+ PartialSpecialization passes were removed. They were unmaintained,
+ buggy, or deemed to be a bad idea.</li>
</ul>
</div>
-
-
-<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="portability">Portability and Supported Platforms</a>
-</div>
-<!-- *********************************************************************** -->
+<!--=========================================================================-->
+<h2>
+<a name="api_changes">Internal API Changes</a>
+</h2>
<div class="doc_text">
-<p>LLVM is known to work on the following platforms:</p>
+<p>In addition, many APIs have changed in this release. Some of the major
+ LLVM API changes are:</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>
+<li>include/llvm/System merged into include/llvm/Support.</li>
+<li>The <a href="http://llvm.org/PR5207">llvm::APInt API</a> was significantly
+ cleaned up.</li>
-<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>
+<li>In the code generator, MVT::Flag was renamed to MVT::Glue to more accurately
+ describe its behavior.</li>
+<li>The system_error header from C++0x was added, and is now pervasively used to
+ capture and handle i/o and other errors in LLVM.</li>
+
+<li>The old sys::Path API has been deprecated in favor of the new PathV2 API,
+ which is more efficient and flexible.</li>
+</ul>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="knownproblems">Known Problems</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
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">
+<h2>
<a name="experimental">Experimental features included with this release</a>
-</div>
+</h2>
<div class="doc_text">
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>
+<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ
+ and XCore backends are experimental.</li>
+<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
+ other than darwin and ELF X86 systems.</li>
+
</ul>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="x86-be">Known problems with the X86 back-end</a>
-</div>
+</h2>
<div class="doc_text">
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>
+ <li>Windows x64 (aka Win64) code generator has a few issues.
+ <ul>
+ <li>llvm-gcc cannot build the mingw-w64 runtime currently
+ due to lack of support for the 'u' inline assembly
+ constraint and for X87 floating point inline assembly.</li>
+ <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt>
+ due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
+ It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
+ <li>Miss-aligned MOVDQA might crash your program. It is due to
+ <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>,
+ lack of handling aligned internal globals.</li>
+ </ul>
+ </li>
+
</ul>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="ppc-be">Known problems with the PowerPC back-end</a>
-</div>
+</h2>
<div class="doc_text">
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="arm-be">Known problems with the ARM back-end</a>
-</div>
+</h2>
<div class="doc_text">
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="sparc-be">Known problems with the SPARC back-end</a>
-</div>
+</h2>
<div class="doc_text">
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="mips-be">Known problems with the MIPS back-end</a>
-</div>
+</h2>
<div class="doc_text">
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="alpha-be">Known problems with the Alpha back-end</a>
-</div>
+</h2>
<div class="doc_text">
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="c-be">Known problems with the C back-end</a>
-</div>
+</h2>
<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>
<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
-</div>
+<h2>
+ <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
+</h2>
<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>
+<p><b>LLVM 2.9 will be the last release of llvm-gcc.</b></p>
-<!-- ======================================================================= -->
-<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>
+<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>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
-</div>
+<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>
-<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>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>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="additionalinfo">Additional Information</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<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
/">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.
projects / oota-llvm.git / blobdiff