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Truncate the release notes so they're ready to accumulate notes for the 2.7 release.
llvm-svn: 94720
This commit is contained in:
Jeffrey Yasskin
parent
68736fc18c
commit
b587f073e5
@ -4,17 +4,17 @@
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 2.6 Release Notes</title>
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<title>LLVM 2.7 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">LLVM 2.6 Release Notes</div>
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<div class="doc_title">LLVM 2.7 Release Notes</div>
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<ol>
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<li><a href="#intro">Introduction</a></li>
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<li><a href="#subproj">Sub-project Status Update</a></li>
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<li><a href="#externalproj">External Projects Using LLVM 2.6</a></li>
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<li><a href="#whatsnew">What's New in LLVM 2.6?</a></li>
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<li><a href="#externalproj">External Projects Using LLVM 2.7</a></li>
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<li><a href="#whatsnew">What's New in LLVM 2.7?</a></li>
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<li><a href="GettingStarted.html">Installation Instructions</a></li>
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<li><a href="#portability">Portability and Supported Platforms</a></li>
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<li><a href="#knownproblems">Known Problems</a></li>
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@ -25,6 +25,12 @@
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<p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
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</div>
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<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.7
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release.<br>
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You may prefer the
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<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6
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Release Notes</a>.</h1>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="intro">Introduction</a>
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@ -34,7 +40,7 @@
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<div class="doc_text">
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<p>This document contains the release notes for the LLVM Compiler
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Infrastructure, release 2.6. Here we describe the status of LLVM, including
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Infrastructure, release 2.7. Here we describe the status of LLVM, including
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major improvements from the previous release and significant known problems.
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All LLVM releases may be downloaded from the <a
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href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
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@ -63,7 +69,7 @@ Almost dead code.
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-->
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<!-- Unfinished features in 2.6:
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<!-- Features that need text if they're finished for 2.7:
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gcc plugin.
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strong phi elim
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variable debug info for optimized code
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@ -94,7 +100,7 @@ Almost dead code.
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<div class="doc_text">
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<p>
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The LLVM 2.6 distribution currently consists of code from the core LLVM
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The LLVM 2.7 distribution currently consists of code from the core LLVM
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repository (which roughly includes the LLVM optimizers, code generators
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and supporting tools), the Clang repository and the llvm-gcc repository. In
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addition to this code, the LLVM Project includes other sub-projects that are in
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@ -111,31 +117,12 @@ development. Here we include updates on these subprojects.
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<div class="doc_text">
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<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
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a set of new 'LLVM native' front-end technologies for the C family of languages.
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LLVM 2.6 is the first release to officially include Clang, and it provides a
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production quality C and Objective-C compiler. If you are interested in <a
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href="http://clang.llvm.org/performance.html">fast compiles</a> and
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<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
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encourage you to try it out. Clang currently compiles typical Objective-C code
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3x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
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(which is when the most pressure is on the frontend).</p>
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<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
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<p>In addition to supporting these languages, C++ support is also <a
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href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
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Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
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If you are interested in Clang C++ support or any other Clang feature, we
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strongly encourage you to get involved on the <a
|
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href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
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list</a>.</p>
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|
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<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
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<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
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|
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<ul>
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<li>C and Objective-C support are now considered production quality.</li>
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<li>AuroraUX, FreeBSD and OpenBSD are now supported.</li>
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<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
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<li>Many many bugs are fixed and lots of features have been added.</li>
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<li>...</li>
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</ul>
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</div>
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@ -146,24 +133,13 @@ list</a>.</p>
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<div class="doc_text">
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<p>Previously announced in the 2.4 and 2.5 LLVM releases, the Clang project also
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<p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also
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includes an early stage static source code analysis tool for <a
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href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
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in C and Objective-C programs. The tool performs checks to find
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bugs that occur on a specific path within a program.</p>
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|
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<p>In the LLVM 2.6 time-frame, the analyzer core has undergone several important
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improvements and cleanups and now includes a new <em>Checker</em> interface that
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is intended to eventually serve as a basis for domain-specific checks. Further,
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in addition to generating HTML files for reporting analysis results, the
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analyzer can now also emit bug reports in a structured XML format that is
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intended to be easily readable by other programs.</p>
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<p>The set of checks performed by the static analyzer continues to expand, and
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future plans for the tool include full source-level inter-procedural analysis
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and deeper checks such as buffer overrun detection. There are many opportunities
|
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to extend and enhance the static analyzer, and anyone interested in working on
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this project is encouraged to get involved!</p>
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<p>In the LLVM 2.7 time-frame, the analyzer core has ...</p>
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</div>
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@ -180,20 +156,13 @@ implementation of the CLI) using LLVM for static and just-in-time
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compilation.</p>
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<p>
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VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
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VMKit version ?? builds with LLVM 2.7 and you can find it on its
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<a href="http://vmkit.llvm.org/releases/">web page</a>. The release includes
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bug fixes, cleanup and new features. The major changes are:</p>
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<ul>
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<li>A new llcj tool to generate shared libraries or executables of Java
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files.</li>
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<li>Cooperative garbage collection. </li>
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<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
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<li>Implementation of a two-word header for Java objects instead of the original
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three-word header. </li>
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<li>Better Java specification-compliance: division by zero checks, stack
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overflow checks, finalization and references support. </li>
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<li>...</li>
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</ul>
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</div>
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@ -249,22 +218,7 @@ KLEE.</p>
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The goal of <a href="http://dragonegg.llvm.org/">DragonEgg</a> is to make
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gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever.
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<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a shared library (dragonegg.so)
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that is loaded by gcc at runtime. It uses the new gcc plugin architecture to
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disable the GCC optimizers and code generators, and schedule the LLVM optimizers
|
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and code generators (or direct output of LLVM IR) instead. Currently only Linux
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and Darwin are supported, and only on x86-32 and x86-64. It should be easy to
|
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add additional unix-like architectures and other processor families. In theory
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it should be possible to use <a href="http://dragonegg.llvm.org/">DragonEgg</a>
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with any language supported by gcc, however only C and Fortran work well for the
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moment. Ada and C++ work to some extent, while Java, Obj-C and Obj-C++ are so
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far entirely untested. Since gcc-4.5 has not yet been released, neither has
|
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<a href="http://dragonegg.llvm.org/">DragonEgg</a>. To build
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<a href="http://dragonegg.llvm.org/">DragonEgg</a> you will need to check out the
|
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development versions of <a href="http://gcc.gnu.org/svn.html/"> gcc</a>,
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<a href="http://llvm.org/docs/GettingStarted.html#checkout">llvm</a> and
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<a href="http://dragonegg.llvm.org/">DragonEgg</a> from their respective
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subversion repositories, and follow the instructions in the
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<a href="http://dragonegg.llvm.org/">DragonEgg</a> README.
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that is loaded by gcc at runtime. It ...
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</p>
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</div>
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@ -277,29 +231,7 @@ subversion repositories, and follow the instructions in the
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<div class="doc_text">
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<p>
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The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
|
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better tools for dealing with machine code, object file formats, etc. The idea
|
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is to be able to generate most of the target specific details of assemblers and
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disassemblers from existing LLVM target .td files (with suitable enhancements),
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and to build infrastructure for reading and writing common object file formats.
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One of the first deliverables is to build a full assembler and integrate it into
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the compiler, which is predicted to substantially reduce compile time in some
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scenarios.
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</p>
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<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
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can reliably parse and pretty print (with some encoding information) a
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darwin/x86 .s file successfully, and has the very early phases of a Mach-O
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assembler in progress. Beyond the MC framework itself, major refactoring of the
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LLVM code generator has started. The idea is to make the code generator reason
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about the code it is producing in a much more semantic way, rather than a
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textual way. For example, the code generator now uses MCSection objects to
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represent section assignments, instead of text strings that print to .section
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directives.</p>
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<p>MC is an early and ongoing project that will hopefully continue to lead to
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many improvements in the code generator and build infrastructure useful for many
|
||||
other situations.
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The LLVM Machine Code (MC) Toolkit project is ...
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</p>
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</div>
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@ -307,7 +239,7 @@ other situations.
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<!-- *********************************************************************** -->
|
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<div class="doc_section">
|
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<a name="externalproj">External Open Source Projects Using LLVM 2.6</a>
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<a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
|
||||
</div>
|
||||
<!-- *********************************************************************** -->
|
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@ -315,7 +247,7 @@ other situations.
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||||
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<p>An exciting aspect of LLVM is that it is used as an enabling technology for
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a lot of other language and tools projects. This section lists some of the
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projects that have already been updated to work with LLVM 2.6.</p>
|
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projects that have already been updated to work with LLVM 2.7.</p>
|
||||
</div>
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||||
|
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|
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@ -376,8 +308,8 @@ built-in list and matrix support (including list and matrix comprehensions) and
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an easy-to-use C interface. The interpreter uses LLVM as a backend to
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JIT-compile Pure programs to fast native code.</p>
|
||||
|
||||
<p>Pure versions 0.31 and later have been tested and are known to work with
|
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LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
|
||||
<p>Pure versions ??? and later have been tested and are known to work with
|
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LLVM 2.7 (and continue to work with older LLVM releases >= 2.3 as well).
|
||||
</p>
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</div>
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@ -460,7 +392,7 @@ code.
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="whatsnew">What's New in LLVM 2.6?</a>
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<a name="whatsnew">What's New in LLVM 2.7?</a>
|
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</div>
|
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<!-- *********************************************************************** -->
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@ -480,28 +412,10 @@ in this section.
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|
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<div class="doc_text">
|
||||
|
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<p>LLVM 2.6 includes several major new capabilities:</p>
|
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<p>LLVM 2.7 includes several major new capabilities:</p>
|
||||
|
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<ul>
|
||||
<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>
|
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and <a href="#mc">machine code toolkit</a> sub-projects.</li>
|
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<li>Debug information now includes line numbers when optimizations are enabled.
|
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This allows statistical sampling tools like OProfile and Shark to map
|
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samples back to source lines.</li>
|
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<li>LLVM now includes new experimental backends to support the MSP430, SystemZ
|
||||
and BlackFin architectures.</li>
|
||||
<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
|
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enables support for <a href="LinkTimeOptimization.html">transparent
|
||||
link-time optimization</a> on ELF targets when used with the Gold binutils
|
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linker.</li>
|
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<li>LLVM now supports doing optimization and code generation on multiple
|
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threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
|
||||
Programmer's Manual</a> for more information.</li>
|
||||
<li>LLVM now has experimental support for <a
|
||||
href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
|
||||
metadata</a> in LLVM IR, though the implementation is not guaranteed to be
|
||||
final and the .bc file format may change in future releases. Debug info
|
||||
does not yet use this format in LLVM 2.6.</li>
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<li>...</li>
|
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</ul>
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</div>
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@ -516,50 +430,7 @@ in this section.
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expose new optimization opportunities:</p>
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|
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<ul>
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<li>The <a href="LangRef.html#i_add">add</a>, <a
|
||||
href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
|
||||
instructions have been split into integer and floating point versions (like
|
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divide and remainder), introducing new <a
|
||||
href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
|
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and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
|
||||
<li>The <a href="LangRef.html#i_add">add</a>, <a
|
||||
href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
|
||||
instructions now support optional "nsw" and "nuw" bits which indicate that
|
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the operation is guaranteed to not overflow (in the signed or
|
||||
unsigned case, respectively). This gives the optimizer more information and
|
||||
can be used for things like C signed integer values, which are undefined on
|
||||
overflow.</li>
|
||||
<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
|
||||
optional "exact" flag which indicates that the result of the division is
|
||||
guaranteed to have a remainder of zero. This is useful for optimizing pointer
|
||||
subtraction in C.</li>
|
||||
<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
|
||||
supports arbitrary integer index values for array/pointer indices. This
|
||||
allows for better code generation on 16-bit pointer targets like PIC16.</li>
|
||||
<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
|
||||
supports an "inbounds" optimization hint that tells the optimizer that the
|
||||
pointer is guaranteed to be within its allocated object.</li>
|
||||
<li>LLVM now support a series of new linkage types for global values which allow
|
||||
for better optimization and new capabilities:
|
||||
<ul>
|
||||
<li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
|
||||
<a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
|
||||
semantics as the non-"odr" linkage types. The difference is that these
|
||||
linkage types indicate that all definitions of the specified function
|
||||
are guaranteed to have the same semantics. This allows inlining
|
||||
templates functions in C++ but not inlining weak functions in C,
|
||||
which previously both got the same linkage type.</li>
|
||||
<li><a href="LangRef.html#linkage_available_externally">available_externally
|
||||
</a> is a new linkage type that gives the optimizer visibility into the
|
||||
definition of a function (allowing inlining and side effect analysis)
|
||||
but that does not cause code to be generated. This allows better
|
||||
optimization of "GNU inline" functions, extern templates, etc.</li>
|
||||
<li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
|
||||
new linkage type (which is only useful on Mac OS X) that is used for
|
||||
some metadata generation and other obscure things.</li>
|
||||
</ul></li>
|
||||
<li>Finally, target-specific intrinsics can now return multiple values, which
|
||||
is useful for modeling target operations with multiple results.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -576,23 +447,7 @@ release includes a few major enhancements and additions to the optimizers:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
|
||||
pass has many improvements that allow it to better promote vector unions,
|
||||
variables which are memset, and much more strange code that can happen to
|
||||
do bitfield accesses to register operations. An interesting change is that
|
||||
it now produces "unusual" integer sizes (like i1704) in some cases and lets
|
||||
other optimizers clean things up.</li>
|
||||
<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
|
||||
promotes small integer induction variables to 64-bit on 64-bit targets,
|
||||
which provides a major performance boost for much numerical code. It also
|
||||
promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
|
||||
expressions (e.g. getelementptrs), as well as integers.</li>
|
||||
<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
|
||||
redundancies of loads in simple cases.</li>
|
||||
<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
|
||||
inlining similar arrays from multiple callees into one caller.</li>
|
||||
<li>LLVM includes a new experimental Static Single Information (SSI)
|
||||
construction pass.</li>
|
||||
<li>...</li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -607,17 +462,7 @@ release includes a few major enhancements and additions to the optimizers:</p>
|
||||
<div class="doc_text">
|
||||
|
||||
<ul>
|
||||
<li>LLVM has a new "EngineBuilder" class which makes it more obvious how to
|
||||
set up and configure an ExecutionEngine (a JIT or interpreter).</li>
|
||||
<li>The JIT now supports generating more than 16M of code.</li>
|
||||
<li>When configured with <tt>--with-oprofile</tt>, the JIT can now inform
|
||||
OProfile about JIT'd code, allowing OProfile to get line number and function
|
||||
name information for JIT'd functions.</li>
|
||||
<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
|
||||
calling almost arbitrary external (natively compiled) functions.</li>
|
||||
<li>Clients of the JIT can now register a 'JITEventListener' object to receive
|
||||
callbacks when the JIT emits or frees machine code. The OProfile support
|
||||
uses this mechanism.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -635,54 +480,7 @@ it run faster:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc as <tt>-dA</tt>
|
||||
and clang as <tt>-fverbose-asm</tt> or <tt>-dA</tt>) now adds a lot of
|
||||
useful information in comments to
|
||||
the generated .s file. This information includes location information (if
|
||||
built with <tt>-g</tt>) and loop nest information.</li>
|
||||
<li>The code generator now supports a new MachineVerifier pass which is useful
|
||||
for finding bugs in targets and codegen passes.</li>
|
||||
<li>The Machine LICM is now enabled by default. It hoists instructions out of
|
||||
loops (such as constant pool loads, loads from read-only stubs, vector
|
||||
constant synthesization code, etc.) and is currently configured to only do
|
||||
so when the hoisted operation can be rematerialized.</li>
|
||||
<li>The Machine Sinking pass is now enabled by default. This pass moves
|
||||
side-effect free operations down the CFG so that they are executed on fewer
|
||||
paths through a function.</li>
|
||||
<li>The code generator now performs "stack slot coloring" of register spills,
|
||||
which allows spill slots to be reused. This leads to smaller stack frames
|
||||
in cases where there are lots of register spills.</li>
|
||||
<li>The register allocator has many improvements to take better advantage of
|
||||
commutable operations, various spiller peephole optimizations, and can now
|
||||
coalesce cross-register-class copies.</li>
|
||||
<li>Tblgen now supports multiclass inheritance and a number of new string and
|
||||
list operations like <tt>!(subst)</tt>, <tt>!(foreach)</tt>, <tt>!car</tt>,
|
||||
<tt>!cdr</tt>, <tt>!null</tt>, <tt>!if</tt>, <tt>!cast</tt>.
|
||||
These make the .td files more expressive and allow more aggressive factoring
|
||||
of duplication across instruction patterns.</li>
|
||||
<li>Target-specific intrinsics can now be added without having to hack VMCore to
|
||||
add them. This makes it easier to maintain out-of-tree targets.</li>
|
||||
<li>The instruction selector is better at propagating information about values
|
||||
(such as whether they are sign/zero extended etc.) across basic block
|
||||
boundaries.</li>
|
||||
<li>The SelectionDAG datastructure has new nodes for representing buildvector
|
||||
and <a href="http://llvm.org/PR2957">vector shuffle</a> operations. This
|
||||
makes operations and pattern matching more efficient and easier to get
|
||||
right.</li>
|
||||
<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
|
||||
the "shrink wrapping" optimization, which moves spills and reloads around in
|
||||
the CFG to avoid doing saves on paths that don't need them.</li>
|
||||
<li>LLVM includes new experimental support for writing ELF .o files directly
|
||||
from the compiler. It works well for many simple C testcases, but doesn't
|
||||
support exception handling, debug info, inline assembly, etc.</li>
|
||||
<li>Targets can now specify register allocation hints through
|
||||
<tt>MachineRegisterInfo::setRegAllocationHint</tt>. A regalloc hint consists
|
||||
of hint type and physical register number. A hint type of zero specifies a
|
||||
register allocation preference. Other hint type values are target specific
|
||||
which are resolved by <tt>TargetRegisterInfo::ResolveRegAllocHint</tt>. An
|
||||
example is the ARM target which uses register hints to request that the
|
||||
register allocator provide an even / odd register pair to two virtual
|
||||
registers.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
</div>
|
||||
|
||||
@ -697,31 +495,7 @@ it run faster:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li>SSE 4.2 builtins are now supported.</li>
|
||||
<li>GCC-compatible soft float modes are now supported, which are typically used
|
||||
by OS kernels.</li>
|
||||
<li>X86-64 now models implicit zero extensions better, which allows the code
|
||||
generator to remove a lot of redundant zexts. It also models the 8-bit "H"
|
||||
registers as subregs, which allows them to be used in some tricky
|
||||
situations.</li>
|
||||
<li>X86-64 now supports the "local exec" and "initial exec" thread local storage
|
||||
model.</li>
|
||||
<li>The vector forms of the <a href="LangRef.html#i_icmp">icmp</a> and <a
|
||||
href="LangRef.html#i_fcmp">fcmp</a> instructions now select to efficient
|
||||
SSE operations.</li>
|
||||
<li>Support for the win64 calling conventions have improved. The primary
|
||||
missing feature is support for varargs function definitions. It seems to
|
||||
work well for many win64 JIT purposes.</li>
|
||||
<li>The X86 backend has preliminary support for <a
|
||||
href="CodeGenerator.html#x86_memory">mapping address spaces to segment
|
||||
register references</a>. This allows you to write GS or FS relative memory
|
||||
accesses directly in LLVM IR for cases where you know exactly what you're
|
||||
doing (such as in an OS kernel). There are some known problems with this
|
||||
support, but it works in simple cases.</li>
|
||||
<li>The X86 code generator has been refactored to move all global variable
|
||||
reference logic to one place
|
||||
(<tt>X86Subtarget::ClassifyGlobalReference</tt>) which
|
||||
makes it easier to reason about.</li>
|
||||
<li>...</li>
|
||||
|
||||
</ul>
|
||||
|
||||
@ -737,11 +511,7 @@ it run faster:</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>Support for floating-point, indirect function calls, and
|
||||
passing/returning aggregate types to functions.
|
||||
<li>The code generator is able to generate debug info into output COFF files.
|
||||
<li>Support for placing an object into a specific section or at a specific
|
||||
address in memory.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
<p>Things not yet supported:</p>
|
||||
@ -764,22 +534,9 @@ it run faster:</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
|
||||
that implement version v7-A of the ARM architecture. The ARM backend now
|
||||
supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.</li>
|
||||
|
||||
<li>The AAPCS-VFP "hard float" calling conventions are also supported with the
|
||||
<tt>-float-abi=hard</tt> flag.</li>
|
||||
|
||||
<li>The ARM calling convention code is now tblgen generated instead of resorting
|
||||
to C++ code.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
<p>These features are still somewhat experimental
|
||||
and subject to change. The Neon intrinsics, in particular, may change in future
|
||||
releases of LLVM. ARMv7 support has progressed a lot on top of tree since 2.6
|
||||
branched.</p>
|
||||
|
||||
|
||||
</div>
|
||||
|
||||
@ -793,11 +550,7 @@ branched.</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>Mips now supports O32 Calling Convention.</li>
|
||||
<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
|
||||
support, lots of bugs fixed.</li>
|
||||
<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
|
||||
Needs more testing.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -814,40 +567,7 @@ branched.</p>
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li>New <a href="http://llvm.org/doxygen/PrettyStackTrace_8h-source.html">
|
||||
<tt>PrettyStackTrace</tt> class</a> allows crashes of llvm tools (and applications
|
||||
that integrate them) to provide more detailed indication of what the
|
||||
compiler was doing at the time of the crash (e.g. running a pass).
|
||||
At the top level for each LLVM tool, it includes the command line arguments.
|
||||
</li>
|
||||
<li>New <a href="http://llvm.org/doxygen/StringRef_8h-source.html">StringRef</a>
|
||||
and <a href="http://llvm.org/doxygen/Twine_8h-source.html">Twine</a> classes
|
||||
make operations on character ranges and
|
||||
string concatenation to be more efficient. <tt>StringRef</tt> is just a <tt>const
|
||||
char*</tt> with a length, <tt>Twine</tt> is a light-weight rope.</li>
|
||||
<li>LLVM has new <tt>WeakVH</tt>, <tt>AssertingVH</tt> and <tt>CallbackVH</tt>
|
||||
classes, which make it easier to write LLVM IR transformations. <tt>WeakVH</tt>
|
||||
is automatically drops to null when the referenced <tt>Value</tt> is deleted,
|
||||
and is updated across a <tt>replaceAllUsesWith</tt> operation.
|
||||
<tt>AssertingVH</tt> aborts the program if the
|
||||
referenced value is destroyed while it is being referenced. <tt>CallbackVH</tt>
|
||||
is a customizable class for handling value references. See <a
|
||||
href="http://llvm.org/doxygen/ValueHandle_8h-source.html">ValueHandle.h</a>
|
||||
for more information.</li>
|
||||
<li>The new '<a href="http://llvm.org/doxygen/Triple_8h-source.html">Triple
|
||||
</a>' class centralizes a lot of logic that reasons about target
|
||||
triples.</li>
|
||||
<li>The new '<a href="http://llvm.org/doxygen/ErrorHandling_8h-source.html">
|
||||
llvm_report_error()</a>' set of APIs allows tools to embed the LLVM
|
||||
optimizer and backend and recover from previously unrecoverable errors.</li>
|
||||
<li>LLVM has new abstractions for <a
|
||||
href="http://llvm.org/doxygen/Atomic_8h-source.html">atomic operations</a>
|
||||
and <a href="http://llvm.org/doxygen/RWMutex_8h-source.html">reader/writer
|
||||
locks</a>.</li>
|
||||
<li>LLVM has new <a href="http://llvm.org/doxygen/SourceMgr_8h-source.html">
|
||||
<tt>SourceMgr</tt> and <tt>SMLoc</tt> classes</a> which implement caret
|
||||
diagnostics and basic include stack processing for simple parsers. It is
|
||||
used by tablegen, llvm-mc, the .ll parser and FileCheck.</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
|
||||
@ -862,32 +582,7 @@ branched.</p>
|
||||
<p>Other miscellaneous features include:</p>
|
||||
|
||||
<ul>
|
||||
<li>LLVM now includes a new internal '<a
|
||||
href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
|
||||
writing much more accurate regression tests that run faster. Please see the
|
||||
<a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
|
||||
Guide</a> for more information.</li>
|
||||
<li>LLVM profile information support has been significantly improved to produce
|
||||
correct use counts, and has support for edge profiling with reduced runtime
|
||||
overhead. Combined, the generated profile information is both more correct and
|
||||
imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
|
||||
CPU2000).</li>
|
||||
<li>The C bindings (in the llvm/include/llvm-c directory) include many newly
|
||||
supported APIs.</li>
|
||||
<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
|
||||
programming language.</li>
|
||||
|
||||
<li>The LLVMC driver has several new features:
|
||||
<ul>
|
||||
<li>Dynamic plugins now work on Windows.</li>
|
||||
<li>New option property: init. Makes possible to provide default values for
|
||||
options defined in plugins (interface to <tt>cl::init</tt>).</li>
|
||||
<li>New example: Skeleton, shows how to create a standalone LLVMC-based
|
||||
driver.</li>
|
||||
<li>New example: mcc16, a driver for the PIC16 toolchain.</li>
|
||||
</ul>
|
||||
</li>
|
||||
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -901,24 +596,11 @@ CPU2000).</li>
|
||||
<div class="doc_text">
|
||||
|
||||
<p>If you're already an LLVM user or developer with out-of-tree changes based
|
||||
on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
|
||||
on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
|
||||
from the previous release.</p>
|
||||
|
||||
<ul>
|
||||
<li>The Itanium (IA64) backend has been removed. It was not actively supported
|
||||
and had bitrotted.</li>
|
||||
<li>The BigBlock register allocator has been removed, it had also bitrotted.</li>
|
||||
<li>The C Backend (<tt>-march=c</tt>) is no longer considered part of the LLVM release
|
||||
criteria. We still want it to work, but no one is maintaining it and it lacks
|
||||
support for arbitrary precision integers and other important IR features.</li>
|
||||
|
||||
<li>All LLVM tools now default to overwriting their output file, behaving more
|
||||
like standard unix tools. Previously, this only happened with the '<tt>-f</tt>'
|
||||
option.</li>
|
||||
<li>LLVM build now builds all libraries as .a files instead of some
|
||||
libraries as relinked .o files. This requires some APIs like
|
||||
InitializeAllTargets.h.
|
||||
</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
|
||||
@ -926,82 +608,7 @@ support for arbitrary precision integers and other important IR features.</li>
|
||||
API changes are:</p>
|
||||
|
||||
<ul>
|
||||
<li>All uses of <tt>hash_set</tt> and <tt>hash_map</tt> have been removed from
|
||||
the LLVM tree and the wrapper headers have been removed.</li>
|
||||
<li>The llvm/Streams.h and <tt>DOUT</tt> member of Debug.h have been removed. The
|
||||
<tt>llvm::Ostream</tt> class has been completely removed and replaced with
|
||||
uses of <tt>raw_ostream</tt>.</li>
|
||||
<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
|
||||
been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
|
||||
now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
|
||||
for clients that will only ever use a single context, the new
|
||||
<tt>getGlobalContext()</tt> API can be used to access a default global
|
||||
context which can be passed in any and all cases where a context is
|
||||
required.
|
||||
<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
|
||||
<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
|
||||
overloaded for floating-point types. Floating-point addition, subtraction
|
||||
and multiplication are now represented with new operators <tt>FAdd</tt>,
|
||||
<tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
|
||||
<tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
|
||||
<tt>CreateNeg</tt> should only be used for integer arithmetic now;
|
||||
<tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
|
||||
<tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
|
||||
<li>The <tt>DynamicLibrary</tt> class can no longer be constructed, its functionality has
|
||||
moved to static member functions.</li>
|
||||
<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
|
||||
takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
|
||||
<tt>false</tt>, an error will be reported if a file with the given name
|
||||
already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
|
||||
be silently truncated (which is the behavior before this flag was
|
||||
added).</li>
|
||||
<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
|
||||
longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt>
|
||||
should be used.</li>
|
||||
|
||||
<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
|
||||
and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
|
||||
or <tt>std::string</tt>, as described in
|
||||
the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
|
||||
clients should be unaffected by this transition, unless they are used to
|
||||
<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
|
||||
2.6:
|
||||
<ul>
|
||||
<li><tt>getNameStr()</tt> is still available, and matches the old
|
||||
behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
|
||||
although more efficient alternatives are now possible.</li>
|
||||
|
||||
<li>If you were just relying on <tt>getName()</tt> being able to be sent to
|
||||
a <tt>std::ostream</tt>, consider migrating
|
||||
to <tt>llvm::raw_ostream</tt>.</li>
|
||||
|
||||
<li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
|
||||
char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
|
||||
Note that this string (as before), may not be the entire name if the
|
||||
name contains embedded null characters.</li>
|
||||
|
||||
<li>If you were using <tt>operator +</tt> on the result of <tt>getName()</tt> and
|
||||
treating the result as an <tt>std::string</tt>, you can either
|
||||
use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
|
||||
could move to a <tt>Twine</tt> based design.</li>
|
||||
|
||||
<li><tt>isName()</tt> should be replaced with comparison
|
||||
against <tt>getName()</tt> (this is now efficient).
|
||||
</ul>
|
||||
</li>
|
||||
|
||||
<li>The registration interfaces for backend Targets has changed (what was
|
||||
previously <tt>TargetMachineRegistry</tt>). For backend authors, see the <a
|
||||
href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
|
||||
guide. For clients, the notable API changes are:
|
||||
<ul>
|
||||
<li><tt>TargetMachineRegistry</tt> has been renamed
|
||||
to <tt>TargetRegistry</tt>.</li>
|
||||
|
||||
<li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
|
||||
function to find targets.</li>
|
||||
</ul>
|
||||
</li>
|
||||
<li>...</li>
|
||||
</ul>
|
||||
|
||||
</div>
|
||||
@ -1055,8 +662,8 @@ there isn't already one.</p>
|
||||
<li>The llvm-gcc bootstrap will fail with some versions of binutils (e.g. 2.15)
|
||||
with a message of "<tt><a href="http://llvm.org/PR5004">Error: can not do 8
|
||||
byte pc-relative relocation</a></tt>" when building C++ code. We intend to
|
||||
fix this on mainline, but a workaround for 2.6 is to upgrade to binutils
|
||||
2.17 or later.</li>
|
||||
fix this on mainline, but a workaround is to upgrade to binutils 2.17 or
|
||||
later.</li>
|
||||
|
||||
<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
|
||||
using the stock GCC 3.x.x series 'out the box',
|
||||
|
||||
Loading…
Reference in New Issue
Block a user