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Update the release notes.

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1,247 docs/ReleaseNotes.html
@@ -5,20 +5,20 @@
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta encoding="utf8">
<link rel="stylesheet" href="llvm.css" type="text/css">
- <title>LLVM 2.8 Release Notes</title>
+ <title>LLVM 2.9 Release Notes</title>
</head>
<body>
-<div class="doc_title">LLVM 2.8 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 2.8</a></li>
- <li><a href="#whatsnew">What's New in LLVM 2.8?</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="#knownproblems">Known Problems</a></li>
<li><a href="#additionalinfo">Additional Information</a></li>
@@ -29,23 +29,23 @@
</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/2.7/docs/ReleaseNotes.html">LLVM 2.7
+<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 2.8. 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>
@@ -62,36 +62,25 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
<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.
- GEPSplitterPass
--->
-
-<!-- Features that need text if they're finished for 2.9:
+<!-- Features that need text if they're finished for 3.1:
+ ARM EHABI
combiner-aa?
strong phi elim
loop dependence analysis
- TBAA
CorrelatedValuePropagation
+ lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
-->
- <!-- Announcement, lldb, libc++ -->
-
-
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="subproj">Sub-project Status Update</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
-The LLVM 2.8 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
@@ -102,9 +91,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
-</div>
+</h2>
<div class="doc_text">
@@ -115,110 +104,61 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
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 2.8 time-frame, the Clang team has made many improvements:</p>
-
- <ul>
- <li>Clang C++ is now feature-complete with respect to the ISO C++ 1998 and 2003 standards.</li>
- <li>Added support for Objective-C++.</li>
- <li>Clang now uses LLVM-MC to directly generate object code and to parse inline assembly (on Darwin).</li>
- <li>Introduced many new warnings, including <code>-Wmissing-field-initializers</code>, <code>-Wshadow</code>, <code>-Wno-protocol</code>, <code>-Wtautological-compare</code>, <code>-Wstrict-selector-match</code>, <code>-Wcast-align</code>, <code>-Wunused</code> improvements, and greatly improved format-string checking.</li>
- <li>Introduced the "libclang" library, a C interface to Clang intended to support IDE clients.</li>
- <li>Added support for <code>#pragma GCC visibility</code>, <code>#pragma align</code>, and others.</li>
- <li>Added support for SSE, AVX, ARM NEON, and AltiVec.</li>
- <li>Improved support for many Microsoft extensions.</li>
- <li>Implemented support for blocks in C++.</li>
- <li>Implemented precompiled headers for C++.</li>
- <li>Improved abstract syntax trees to retain more accurate source information.</li>
- <li>Added driver support for handling LLVM IR and bitcode files directly.</li>
- <li>Major improvements to compiler correctness for exception handling.</li>
- <li>Improved generated code quality in some areas:
- <ul>
- <li>Good code generation for X86-32 and X86-64 ABI handling.</li>
- <li>Improved code generation for bit-fields, although important work remains.</li>
- </ul>
- </li>
- </ul>
-</div>
-
-<!--=========================================================================-->
-<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>The LLVM 2.8 release fixes a number of bugs and slightly improves precision
- over 2.7, but there are no major new features in the release.
+(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>
+<ul>
+</ul>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
-</div>
+<h2>
+<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</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, dragonegg in theory does not require any gcc-4.5
-modifications whatsoever (currently one small patch is needed) thanks to the
-new <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>.
-DragonEgg is a gcc plugin that makes gcc-4.5 use the LLVM optimizers and code
-generators instead of gcc's, just like with llvm-gcc.
+<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>
-DragonEgg is still a work in progress, but it is able to compile a lot of code,
-for example all of gcc, LLVM and clang. Currently Ada, C, C++ and Fortran work
-well, while all other languages either don't work at all or only work poorly.
-For the moment only the x86-32 and x86-64 targets are supported, and only on
-linux and darwin (darwin may need additional gcc patches).
-</p>
-
-<p>
-The 2.8 release has the following notable changes:
+The 2.9 release has the following notable changes:
<ul>
-<li>The plugin loads faster due to exporting fewer symbols.</li>
-<li>Additional vector operations such as addps256 are now supported.</li>
-<li>Ada global variables with no initial value are no longer zero initialized,
-resulting in better optimization.</li>
-<li>The '-fplugin-arg-dragonegg-enable-gcc-optzns' flag now runs all gcc
-optimizers, rather than just a handful.</li>
-<li>Fortran programs using common variables now link correctly.</li>
-<li>GNU OMP constructs no longer crash the compiler.</li>
+<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 class="doc_subsection">
-<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
-</div>
-
-<div class="doc_text">
-<p>
-The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
-a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
-just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage
-collectors, and can be configured to use MMTk's copy mark-sweep garbage
-collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained.
-</p>
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
-</div>
+</h2>
<div class="doc_text">
<p>
@@ -231,19 +171,20 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
this and other low-level routines (some are 3x faster than the equivalent
libgcc routines).</p>
-<p>
-All of the code in the compiler-rt project is available under the standard LLVM
-License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports
-soft floating point (for targets that don't have a real floating point unit),
-and includes an extensive testsuite for the "blocks" language feature and the
-blocks runtime included in compiler_rt.</p>
+<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">
+<h2>
<a name="lldb">LLDB: Low Level Debugger</a>
-</div>
+</h2>
<div class="doc_text">
<p>
@@ -254,18 +195,18 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
LLVM disassembler and the LLVM JIT.</p>
<p>
-LLDB is in early development and not included as part of the LLVM 2.8 release,
-but is mature enough to support basic debugging scenarios on Mac OS X in C,
-Objective-C and C++. We'd really like help extending and expanding LLDB to
-support new platforms, new languages, new architectures, and new features.
-</p>
+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>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="libc++">libc++: C++ Standard Library</a>
-</div>
+</h2>
<div class="doc_text">
<p>
@@ -275,19 +216,54 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
delivering great performance.</p>
<p>
-As of the LLVM 2.8 release, libc++ is virtually feature complete, but would
-benefit from more testing and better integration with Clang++. It is also
-looking forward to the C++ committee finalizing the C++'0x standard.
+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>
+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>
+<!--=========================================================================-->
+<h2>
+<a name="LLBrowse">LLBrowse: IR Browser</a>
+</h2>
+
+<div class="doc_text">
+<p>
+<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>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
+<h2>
+<a name="vmkit">VMKit</a>
+</h2>
+
+<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 class="doc_text">
<p>
@@ -298,171 +274,145 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
be used to verify some algorithms.
</p>
-<p>Although KLEE does not have any major new features as of 2.8, we have made
-various minor improvements, particular to ease development:</p>
-<ul>
- <li>Added support for LLVM 2.8. KLEE currently maintains compatibility with
- LLVM 2.6, 2.7, and 2.8.</li>
- <li>Added a buildbot for 2.6, 2.7, and trunk. A 2.8 buildbot will be coming
- soon following release.</li>
- <li>Fixed many C++ code issues to allow building with Clang++. Mostly
- complete, except for the version of MiniSAT which is inside the KLEE STP
- version.</li>
- <li>Improved support for building with separate source and build
- directories.</li>
- <li>Added support for "long double" on x86.</li>
- <li>Initial work on KLEE support for using 'lit' test runner instead of
- DejaGNU.</li>
- <li>Added <tt>configure</tt> support for using an external version of
- STP.</li>
-</ul>
-
-</div>
+<p>UPDATE!</p>
+</div>-->
<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="externalproj">External Open Source Projects Using LLVM 2.8</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 2.8.</p>
+ projects that have already been updated to work with LLVM 2.9.</p>
</div>
+
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="tce">TTA-based Codesign Environment (TCE)</a>
-</div>
+<h2>Crack Programming Language</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>
-
+<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="Horizon">Horizon Bytecode Compiler</a>
-</div>
-
+<h2>TTA-based Codesign Environment (TCE)</h2>
+
<div class="doc_text">
-<p>
-<a href="http://www.quokforge.org/projects/horizon">Horizon</a> is a bytecode
-language and compiler written on top of LLVM, intended for producing
-single-address-space managed code operating systems that
-run faster than the equivalent multiple-address-space C systems.
-More in-depth blurb is available on the <a
-href="http://www.quokforge.org/projects/horizon/wiki/Wiki">wiki</a>.</p>
-
+<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="clamav">Clam AntiVirus</a>
+<h2>PinaVM</h2>
+
+<div class="doc_text">
+<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>
+<!--=========================================================================-->
+<h2>Pure</h2>
+
<div class="doc_text">
-<p>
-<a href="http://www.clamav.net">Clam AntiVirus</a> is an open source (GPL)
-anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail
-gateways. Since version 0.96 it has <a
-href="http://vrt-sourcefire.blogspot.com/2010/09/introduction-to-clamavs-low-level.html">bytecode
-signatures</a> that allow writing detections for complex malware. It
-uses LLVM's JIT to speed up the execution of bytecode on
-X86, X86-64, PPC32/64, falling back to its own interpreter otherwise.
-The git version was updated to work with LLVM 2.8.
-</p>
-
-<p>The <a
-href="http://git.clamav.net/gitweb?p=clamav-bytecode-compiler.git;a=blob_plain;f=docs/user/clambc-user.pdf">
-ClamAV bytecode compiler</a> uses Clang and LLVM to compile a C-like
-language, insert runtime checks, and generate ClamAV bytecode.</p>
-
+<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 &gt;= 2.5).</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="pure">Pure</a>
-</div>
+<h2 id="icedtea">IcedTea Java Virtual Machine Implementation</h2>
<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 0.44 and later have been tested and are known to work with
-LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).</p>
+<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> 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 &gt;= 2.6 as well).</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
-</div>
-
+<h2>Glasgow Haskell Compiler (GHC)</h2>
+
<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
+<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 <a
-href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
-code generator</a>. GHC supports LLVM 2.7 and later.</p>
-
+supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="Clay">Clay Programming Language</a>
-</div>
-
+<h2>Polly - Polyhedral optimizations for LLVM</h2>
+
<div class="doc_text">
-<p>
-<a href="http://tachyon.in/clay/">Clay</a> is a new systems programming
-language that is specifically designed for generic programming. It makes
-generic programming very concise thanks to whole program type propagation. It
-uses LLVM as its backend.</p>
-
+<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>
<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="llvm-py">llvm-py Python Bindings for LLVM</a>
-</div>
+<h2>Rubinius</h2>
<div class="doc_text">
-<p>
-<a href="http://www.mdevan.org/llvm-py/">llvm-py</a> has been updated to work
-with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a
-compiler backend or a VM in Python.</p>
-
+ <p><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>
@@ -477,118 +427,14 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
audio signal processing. The name FAUST stands for Functional AUdio STream. Its
programming model combines two approaches: functional programming and block
diagram composition. In addition with the C, C++, JAVA output formats, the
-Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and
-2.8.</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="jade">Jade Just-in-time Adaptive Decoder Engine</a>
-</div>
-
-<div class="doc_text">
-<p><a
-href="http://sourceforge.net/apps/trac/orcc/wiki/JadeDocumentation">Jade</a>
-(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using
-LLVM for just-in-time compilation of video decoder configurations. Those
-configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee.
-MPEG RVC standard is built on a stream-based dataflow representation of
-decoders. It is composed of a standard library of coding tools written in
-RVC-CAL language and a dataflow configuration &#8212; block diagram &#8212;
-of a decoder.</p>
-
-<p>Jade project is hosted as part of the <a href="http://orcc.sf.net">Open
-RVC-CAL Compiler</a> and requires it to translate the RVC-CAL standard library
-of video coding tools into an LLVM assembly code.</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="neko_llvm_jit">LLVM JIT for Neko VM</a>
-</div>
-
-<div class="doc_text">
-<p><a href="http://github.com/vava/neko_llvm_jit">Neko LLVM JIT</a>
-replaces the standard Neko JIT with an LLVM-based implementation. While not
-fully complete, it is already providing a 1.5x speedup on 64-bit systems.
-Neko LLVM JIT requires LLVM 2.8 or later.</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="crack">Crack Scripting Language</a>
-</div>
-
-<div class="doc_text">
-<p>
-<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide
-the ease of development of a scripting language with the performance of a
-compiled language. The language derives concepts from C++, Java and Python,
-incorporating object-oriented programming, operator overloading and strong
-typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release
-builds on LLVM 2.8.</p>
+Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7-2.9.</p>
</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="DresdenTM">Dresden TM Compiler (DTMC)</a>
-</div>
-
-<div class="doc_text">
-<p>
-<a href="http://tm.inf.tu-dresden.de">DTMC</a> provides support for
-Transactional Memory, which is an easy-to-use and efficient way to synchronize
-accesses to shared memory. Transactions can contain normal C/C++ code (e.g.,
-<code>__transaction { list.remove(x); x.refCount--; }</code>) and will be executed
-virtually atomically and isolated from other transactions.</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="Kai">Kai Programming Language</a>
-</div>
-
-<div class="doc_text">
-<p>
-<a href="http://www.oriontransfer.co.nz/research/kai">Kai</a> (Japanese 会 for
-meeting/gathering) is an experimental interpreter that provides a highly
-extensible runtime environment and explicit control over the compilation
-process. Programs are defined using nested symbolic expressions, which are all
-parsed into first-class values with minimal intrinsic semantics. Kai can
-generate optimised code at run-time (using LLVM) in order to exploit the nature
-of the underlying hardware and to integrate with external software libraries.
-It is a unique exploration into world of dynamic code compilation, and the
-interaction between high level and low level semantics.</p>
-
-</div>
-
-<!--=========================================================================-->
-<div class="doc_subsection">
-<a name="OSL">OSL: Open Shading Language</a>
-</div>
-
-<div class="doc_text">
-<p>
-<a href="http://code.google.com/p/openshadinglanguage/">OSL</a> is a shading
-language designed for use in physically based renderers and in particular
-production rendering. By using LLVM instead of the interpreter, it was able to
-meet its performance goals (&gt;= C-code) while retaining the benefits of
-runtime specialization and a portable high-level language.
-</p>
-
-</div>
-
-
-
+
<!-- *********************************************************************** -->
-<div class="doc_section">
- <a name="whatsnew">What's New in LLVM 2.8?</a>
-</div>
+<h1>
+ <a name="whatsnew">What's New in LLVM 2.9?</a>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">
@@ -601,106 +447,134 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="majorfeatures">Major New Features</a>
-</div>
+</h2>
<div class="doc_text">
-<p>LLVM 2.8 includes several major new capabilities:</p>
+<p>LLVM 2.9 includes several major new capabilities:</p>
<ul>
-<li>As mentioned above, <a href="#libc++">libc++</a> and <a
- href="#lldb">LLDB</a> are major new additions to the LLVM collective.</li>
-<li>LLVM 2.8 now has pretty decent support for debugging optimized code. You
- should be able to reliably get debug info for function arguments, assuming
- that the value is actually available where you have stopped.</li>
-<li>A new 'llvm-diff' tool is available that does a semantic diff of .ll
- files.</li>
-<li>The <a href="#mc">MC subproject</a> has made major progress in this release.
- Direct .o file writing support for darwin/x86[-64] is now reliable and
- support for other targets and object file formats are in progress.</li>
-</ul>
+
+<li>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>
+
+<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>
+
+<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>The <a href="LangRef.html#int_libc">memcpy, memmove, and memset</a>
- intrinsics now take address space qualified pointers and a bit to indicate
- whether the transfer is "<a href="LangRef.html#volatile">volatile</a>" or not.
-</li>
-<li>Per-instruction debug info metadata is much faster and uses less memory by
- using the new DebugLoc class.</li>
-<li>LLVM IR now has a more formalized concept of "<a
- href="LangRef.html#trapvalues">trap values</a>", which allow the optimizer
- to optimize more aggressively in the presence of undefined behavior, while
- still producing predictable results.</li>
-<li>LLVM IR now supports two new <a href="LangRef.html#linkage">linkage
- types</a> (linker_private_weak and linker_private_weak_def_auto) which map
- onto some obscure MachO concepts.</li>
+<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">
<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>As mentioned above, the optimizer now has support for updating debug
- information as it goes. A key aspect of this is the new <a
- href="SourceLevelDebugging.html#format_common_value">llvm.dbg.value</a>
- intrinsic. This intrinsic represents debug info for variables that are
- promoted to SSA values (typically by mem2reg or the -scalarrepl passes).</li>
-
-<li>The JumpThreading pass is now much more aggressive about implied value
- relations, allowing it to thread conditions like "a == 4" when a is known to
- be 13 in one of the predecessors of a block. It does this in conjunction
- with the new LazyValueInfo analysis pass.</li>
-<li>The new RegionInfo analysis pass identifies single-entry single-exit regions
- in the CFG. You can play with it with the "opt -regions -analyze" or
- "opt -view-regions" commands.</li>
-<li>The loop optimizer has significantly improved strength reduction and analysis
- capabilities. Notably it is able to build on the trap value and signed
- integer overflow information to optimize &lt;= and &gt;= loops.</li>
-<li>The CallGraphSCCPassManager now has some basic support for iterating within
- an SCC when a optimizer devirtualizes a function call. This allows inlining
- through indirect call sites that are devirtualized by store-load forwarding
- and other optimizations.</li>
-<li>The new <A href="Passes.html#loweratomic">-loweratomic</a> pass is available
- to lower atomic instructions into their non-atomic form. This can be useful
- to optimize generic code that expects to run in a single-threaded
- environment.</li>
-</ul>
+<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>
-<!--
-<p>In addition to these features that are done in 2.8, there is preliminary
- support in the release for Type Based Alias Analysis
- Preliminary work on TBAA but not usable in 2.8.
- New CorrelatedValuePropagation pass, not on by default in 2.8 yet.
--->
+<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 &lt; a) ...
+ </pre>
+ into:
+ <pre>
+ addq %rdi, %rbx
+ jno LBB0_2
+ </pre>
+</li>
+
+</ul>
</div>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="mc">MC Level Improvements</a>
-</div>
+</h2>
<div class="doc_text">
<p>
@@ -709,40 +583,52 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
and a number of other related areas that CPU instruction-set level tools work
in.</p>
-<p>The MC subproject has made great leaps in LLVM 2.8. For example, support for
- directly writing .o files from LLC (and clang) now works reliably for
- darwin/x86[-64] (including inline assembly support) and the integrated
- assembler is turned on by default in Clang for these targets. This provides
- improved compile times among other things.</p>
-
<ul>
-<li>The entire compiler has converted over to using the MCStreamer assembler API
- instead of writing out a .s file textually.</li>
-<li>The "assembler parser" is far more mature than in 2.7, supporting a full
- complement of directives, now supports assembler macros, etc.</li>
-<li>The "assembler backend" has been completed, including support for relaxation
- relocation processing and all the other things that an assembler does.</li>
-<li>The MachO file format support is now fully functional and works.</li>
-<li>The MC disassembler now fully supports ARM and Thumb. ARM assembler support
- is still in early development though.</li>
-<li>The X86 MC assembler now supports the X86 AES and AVX instruction set.</li>
-<li>Work on ELF and COFF object files and ARM target support is well underway,
- but isn't useful yet in LLVM 2.8. Please contact the llvmdev mailing list
- if you're interested in this.</li>
+<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>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>
<!--=========================================================================-->
-<div class="doc_subsection">
+<h2>
<a name="codegen">Target Independent Code Generator Improvements</a>
-</div>
+</h2>
<div class="doc_text">
@@ -751,343 +637,187 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
it run faster:</p>
<ul>
-<li>The clang/gcc -momit-leaf-frame-pointer argument is now supported.</li>
-<li>The clang/gcc -ffunction-sections and -fdata-sections arguments are now
- supported on ELF targets (like GCC).</li>
-<li>The MachineCSE pass is now tuned and on by default. It eliminates common
- subexpressions that are exposed when lowering to machine instructions.</li>
-<li>The "local" register allocator was replaced by a new "fast" register
- allocator. This new allocator (which is often used at -O0) is substantially
- faster and produces better code than the old local register allocator.</li>
-<li>A new LLC "-regalloc=default" option is available, which automatically
- chooses a register allocator based on the -O optimization level.</li>
-<li>The common code generator code was modified to promote illegal argument and
- return value vectors to wider ones when possible instead of scalarizing
- them. For example, &lt;3 x float&gt; will now pass in one SSE register
- instead of 3 on X86. This generates substantially better code since the
- rest of the code generator was already expecting this.</li>
-<li>The code generator uses a new "COPY" machine instruction. This speeds up
- the code generator and eliminates the need for targets to implement the
- isMoveInstr hook. Also, the copyRegToReg hook was renamed to copyPhysReg
- and simplified.</li>
-<li>The code generator now has a "LocalStackSlotPass", which optimizes stack
- slot access for targets (like ARM) that have limited stack displacement
- addressing.</li>
-<li>A new "PeepholeOptimizer" is available, which eliminates sign and zero
- extends, and optimizes away compare instructions when the condition result
- is available from a previous instruction.</li>
-<li>Atomic operations now get legalized into simpler atomic operations if not
- natively supported, easing the implementation burden on targets.</li>
-<li>We have added two new bottom-up pre-allocation register pressure aware schedulers:
-<ol>
-<li>The hybrid scheduler schedules aggressively to minimize schedule length when registers are available and avoid overscheduling in high pressure situations.</li>
-<li>The instruction-level-parallelism scheduler schedules for maximum ILP when registers are available and avoid overscheduling in high pressure situations.</li>
-</ol></li>
-<li>The tblgen type inference algorithm was rewritten to be more consistent and
- diagnose more target bugs. If you have an out-of-tree backend, you may
- find that it finds bugs in your target description. This support also
- allows limited support for writing patterns for instructions that return
- multiple results (e.g. a virtual register and a flag result). The
- 'parallel' modifier in tblgen was removed, you should use the new support
- for multiple results instead.</li>
-<li>A new (experimental) "-rendermf" pass is available which renders a
- MachineFunction into HTML, showing live ranges and other useful
- details.</li>
-<li>The new SubRegIndex tablegen class allows subregisters to be indexed
- symbolically instead of numerically. If your target uses subregisters you
- will need to adapt to use SubRegIndex when you upgrade to 2.8.</li>
-<!-- SplitKit -->
-
-<li>The -fast-isel instruction selection path (used at -O0 on X86) was rewritten
- to work bottom-up on basic blocks instead of top down. This makes it
- slightly faster (because the MachineDCE pass is not needed any longer) and
- allows it to generate better code in some cases.</li>
+<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 and major changes in the X86 target include:
</p>
<ul>
-<li>The X86 backend now supports holding X87 floating point stack values
- in registers across basic blocks, dramatically improving performance of code
- that uses long double, and when targeting CPUs that don't support SSE.</li>
-
-<li>The X86 backend now uses a SSEDomainFix pass to optimize SSE operations. On
- Nehalem ("Core i7") and newer CPUs there is a 2 cycle latency penalty on
- using a register in a different domain than where it was defined. This pass
- optimizes away these stalls.</li>
-
-<li>The X86 backend now promotes 16-bit integer operations to 32-bits when
- possible. This avoids 0x66 prefixes, which are slow on some
- microarchitectures and bloat the code on all of them.</li>
-
-<li>The X86 backend now supports the Microsoft "thiscall" calling convention,
- and a <a href="LangRef.html#callingconv">calling convention</a> to support
- <a href="#GHC">ghc</a>.</li>
-
-<li>The X86 backend supports a new "llvm.x86.int" intrinsic, which maps onto
- the X86 "int $42" and "int3" instructions.</li>
-
-<li>At the IR level, the &lt;2 x float&gt; datatype is now promoted and passed
- around as a &lt;4 x float&gt; instead of being passed and returned as an MMX
- vector. If you have a frontend that uses this, please pass and return a
- &lt;2 x i32&gt; instead (using bitcasts).</li>
-
-<li>When printing .s files in verbose assembly mode (the default for clang -S),
- the X86 backend now decodes X86 shuffle instructions and prints human
- readable comments after the most inscrutable of them, e.g.:
-
-<pre>
- insertps $113, %xmm3, %xmm0 <i># xmm0 = zero,xmm0[1,2],xmm3[1]</i>
- unpcklps %xmm1, %xmm0 <i># xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]</i>
- pshufd $1, %xmm1, %xmm1 <i># xmm1 = xmm1[1,0,0,0]</i>
-</pre>
+<li>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 &lt;2 x i32&gt; 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 optimizes tail calls into jumps.</li>
-<li>Scheduling is improved through the new list-hybrid scheduler as well
- as through better modeling of structural hazards.</li>
-<li><a href="LangRef.html#int_fp16">Half float</a> instructions are now
- supported.</li>
-<li>NEON support has been improved to model instructions which operate onto
- multiple consecutive registers more aggressively. This avoids lots of
- extraneous register copies.</li>
-<li>The ARM backend now uses a new "ARMGlobalMerge" pass, which merges several
- global variables into one, saving extra address computation (all the global
- variables can be accessed via same base address) and potentially reducing
- register pressure.</li>
-
-<li>The ARM backend has received many minor improvements and tweaks which lead
- to substantially better performance in a wide range of different scenarios.
-</li>
+<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 NEON intrinsics have been substantially reworked to reduce
- redundancy and improve code generation. Some of the major changes are:
- <ol>
- <li>
- All of the NEON load and store intrinsics (llvm.arm.neon.vld* and
- llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes
- of the memory being accessed.
- </li>
- <li>
- The llvm.arm.neon.vaba intrinsic (vector absolute difference and
- accumulate) has been removed. This operation is now represented using
- the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a
- vector add.
- </li>
- <li>
- The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening
- vector absolute difference with and without accumulation) have been removed.
- They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute
- difference) followed by a vector zero-extend operation, and for vabal,
- a vector add.
- </li>
- <li>
- The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic
- are now replaced by vector truncate operations.
- </li>
- <li>
- The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been
- removed. They are now represented as vector sign-extend (vmovls) and
- zero-extend (vmovlu) operations.
- </li>
- <li>
- The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and
- llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have
- been removed. They are replaced by vector add and vector subtract operations
- where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either
- sign-extended or zero-extended.
- </li>
- <li>
- The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and
- llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without
- accumulation and subtraction) have been removed. These operations are now
- represented as vector multiplications where the operands are either
- sign-extended or zero-extended, followed by a vector add for vmlal or a
- vector subtract for vmlsl. Note that the polynomial vector multiply
- intrinsic, llvm.arm.neon.vmullp, remains unchanged.
- </li>
- </ol>
-</li>
+<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>
+
+<!--=========================================================================-->
+<h2>
+<a name="OtherTS">Other Target Specific Improvements</a>
+</h2>
+
+<div class="doc_text">
+<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>
+
+<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>
+
+</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 2.7, 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>The build configuration machinery changed the output directory names. It
- wasn't clear to many people that a "Release-Asserts" build was a release build
- without asserts. To make this more clear, "Release" does not include
- assertions and "Release+Asserts" does (likewise, "Debug" and
- "Debug+Asserts").</li>
-<li>The MSIL Backend was removed, it was unsupported and broken.</li>
-<li>The ABCD, SSI, and SCCVN passes were removed. These were not fully
- functional and their behavior has been or will be subsumed by the
- LazyValueInfo pass.</li>
-<li>The LLVM IR 'Union' feature was removed. While this is a desirable feature
- for LLVM IR to support, the existing implementation was half baked and
- barely useful. We'd really like anyone interested to resurrect the work and
- finish it for a future release.</li>
-<li>If you're used to reading .ll files, you'll probably notice that .ll file
- dumps don't produce #uses comments anymore. To get them, run a .bc file
- through "llvm-dis --show-annotations".</li>
-<li>Target triples are now stored in a normalized form, and all inputs from
- humans are expected to be normalized by Triple::normalize before being
- stored in a module triple or passed to another library.</li>
-</ul>
+<li><b>This is the last release to support the llvm-gcc frontend.</b></li>
+<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>
+<li>LLVM IR and other tools always work on normalized target triples (which have
+ been run through <tt>Triple::normalize</tt>).</li>
-<p>In addition, many APIs have changed in this release. Some of the major LLVM
-API changes are:</p>
-<ul>
-<li>LLVM 2.8 changes the internal order of operands in <a
- href="http://llvm.org/doxygen/classllvm_1_1InvokeInst.html"><tt>InvokeInst</tt></a>
- and <a href="http://llvm.org/doxygen/classllvm_1_1CallInst.html"><tt>CallInst</tt></a>.
- To be portable across releases, please use the <tt>CallSite</tt> class and the
- high-level accessors, such as <tt>getCalledValue</tt> and
- <tt>setUnwindDest</tt>.
-</li>
-<li>
- You can no longer pass use_iterators directly to cast&lt;&gt; (and similar),
- because these routines tend to perform costly dereference operations more
- than once. You have to dereference the iterators yourself and pass them in.
-</li>
-<li>
- llvm.memcpy.*, llvm.memset.*, llvm.memmove.* intrinsics take an extra
- parameter now ("i1 isVolatile"), totaling 5 parameters, and the pointer
- operands are now address-space qualified.
- If you were creating these intrinsic calls and prototypes yourself (as opposed
- to using Intrinsic::getDeclaration), you can use
- UpgradeIntrinsicFunction/UpgradeIntrinsicCall to be portable across releases.
-</li>
-<li>
- SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode.
- Change your code to use
- SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)).
-</li>
-<li>
- The <tt>RegisterPass</tt> and <tt>RegisterAnalysisGroup</tt> templates are
- considered deprecated, but continue to function in LLVM 2.8. Clients are
- strongly advised to use the upcoming <tt>INITIALIZE_PASS()</tt> and
- <tt>INITIALIZE_AG_PASS()</tt> macros instead.
-</li>
-<li>
- The constructor for the Triple class no longer tries to understand odd triple
- specifications. Frontends should ensure that they only pass valid triples to
- LLVM. The Triple::normalize utility method has been added to help front-ends
- deal with funky triples.
-</li>
-<li>
- The signature of the <tt>GCMetadataPrinter::finishAssembly</tt> virtual
- function changed: the <tt>raw_ostream</tt> and <tt>MCAsmInfo</tt> arguments
- were dropped. GC plugins which compute stack maps must be updated to avoid
- having the old definition overload the new signature.
-</li>
-<li>
- The signature of <tt>MemoryBuffer::getMemBuffer</tt> changed. Unfortunately
- calls intended for the old version still compile, but will not work correctly,
- leading to a confusing error about an invalid header in the bitcode.
-</li>
-
-<li>
- Some APIs were renamed:
- <ul>
- <li>llvm_report_error -&gt; report_fatal_error</li>
- <li>llvm_install_error_handler -&gt; install_fatal_error_handler</li>
- <li>llvm::DwarfExceptionHandling -&gt; llvm::JITExceptionHandling</li>
- <li>VISIBILITY_HIDDEN -&gt; LLVM_LIBRARY_VISIBILITY</li>
- </ul>
-</li>
+<li>The target triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32
+ instead.</li>
-<li>
- Some public headers were renamed:
- <ul>
- <li><tt>llvm/Assembly/AsmAnnotationWriter.h</tt> was renamed
- to <tt>llvm/Assembly/AssemblyAnnotationWriter.h</tt>
- </li>
- </ul>
+<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_subsection">
-<a name="devtree_changes">Development Infrastructure Changes</a>
-</div>
+<h2>
+<a name="api_changes">Internal API Changes</a>
+</h2>
<div class="doc_text">
-<p>This section lists changes to the LLVM development infrastructure. This
-mostly impacts users who actively work on LLVM or follow development on
-mainline, but may also impact users who leverage the LLVM build infrastructure
-or are interested in LLVM qualification.</p>
+<p>In addition, many APIs have changed in this release. Some of the major
+ LLVM API changes are:</p>
<ul>
- <li>The default for <tt>make check</tt> is now to use
- the <a href="http://llvm.org/cmds/lit.html">lit</a> testing tool, which is
- part of LLVM itself. You can use <tt>lit</tt> directly as well, or use
- the <tt>llvm-lit</tt> tool which is created as part of a Makefile or CMake
- build (and knows how to find the appropriate tools). See the <tt>lit</tt>
- documentation and the <a href="http://blog.llvm.org/2009/12/lit-it.html">blog
- post</a>, and <a href="http://llvm.org/bugs/show_bug.cgi?id=5217">PR5217</a>
- for more information.</li>
-
- <li>The LLVM <tt>test-suite</tt> infrastructure has a new "simple" test format
- (<tt>make TEST=simple</tt>). The new format is intended to require only a
- compiler and not a full set of LLVM tools. This makes it useful for testing
- released compilers, for running the test suite with other compilers (for
- performance comparisons), and makes sure that we are testing the compiler as
- users would see it. The new format is also designed to work using reference
- outputs instead of comparison to a baseline compiler, which makes it run much
- faster and makes it less system dependent.</li>
-
- <li>Significant progress has been made on a new interface to running the
- LLVM <tt>test-suite</tt> (aka the LLVM "nightly tests") using
- the <a href="http://llvm.org/docs/lnt">LNT</a> infrastructure. The LNT
- interface to the <tt>test-suite</tt> brings significantly improved reporting
- capabilities for monitoring the correctness and generated code quality
- produced by LLVM over time.</li>
+<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>
+
+<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">
@@ -1100,9 +830,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="experimental">Experimental features included with this release</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1114,18 +844,19 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
<ul>
-<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, SystemZ
+<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-i386 and darwin-x86_64.</li>
+ 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">
@@ -1134,21 +865,31 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
all <a href="http://llvm.org/PR879">inline assembly that uses the X86
floating point stack</a>. It supports the 'f' and 't' constraints, but not
'u'.</li>
- <li>Win64 code generation wasn't widely tested. Everything should work, but we
- expect small issues to happen. Also, llvm-gcc cannot build the mingw64
- runtime currently due to lack of support for the 'u' inline assembly
- constraint and for X87 floating point inline assembly.</li>
<li>The X86-64 backend does not yet support the LLVM IR instruction
<tt>va_arg</tt>. Currently, front-ends support variadic
argument constructs on X86-64 by lowering them manually.</li>
+ <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">
@@ -1160,9 +901,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="arm-be">Known problems with the ARM back-end</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1177,9 +918,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="sparc-be">Known problems with the SPARC back-end</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1191,9 +932,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="mips-be">Known problems with the MIPS back-end</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1204,9 +945,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="alpha-be">Known problems with the Alpha back-end</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1219,9 +960,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="c-be">Known problems with the C back-end</a>
-</div>
+</h2>
<div class="doc_text">
@@ -1242,12 +983,14 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h2>
<a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
-</div>
+</h2>
<div class="doc_text">
+<p><b>LLVM 2.9 will be the last release of llvm-gcc.</b></p>
+
<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
@@ -1268,9 +1011,9 @@ <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h1>
<a name="additionalinfo">Additional Information</a>
-</div>
+</h1>
<!-- *********************************************************************** -->
<div class="doc_text">

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