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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 7c8e7965e1726ed3fa5e45fea02d93c8df1920ed / . / docs / ReleaseNotes.html
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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4<head>
Reid Spencer6454ed32004-11-18 18:38:58 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]6 <link rel="stylesheet" href="llvm.css" type="text/css">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]7 <title>LLVM 2.7 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]10
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]11<div class="doc_title">LLVM 2.7 Release Notes</div>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]12
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]13<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greifee2187a2010-04-22 10:21:43 +0000[diff] [blame]14 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]15
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]16<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]18 <li><a href="#subproj">Sub-project Status Update</a></li>
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]19 <li><a href="#externalproj">External Projects Using LLVM 2.7</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 2.7?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]21 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]22 <li><a href="#portability">Portability and Supported Platforms</a></li>
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]23 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]24 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]25</ol>
26
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]27<div class="doc_author">
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]28 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]29</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]30
Chris Lattner00736fc2010-04-13 06:37:00 +0000[diff] [blame]31<!--
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]32<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]33release.<br>
34You may prefer the
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]35<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.7
Chris Lattner00736fc2010-04-13 06:37:00 +0000[diff] [blame]36Release Notes</a>.</h1>-->
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]37
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]38<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]39<div class="doc_section">
40 <a name="intro">Introduction</a>
41</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]42<!-- *********************************************************************** -->
43
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]44<div class="doc_text">
45
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]46<p>This document contains the release notes for the LLVM Compiler
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]47Infrastructure, release 2.7. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]48major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]49All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]50href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]51
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]52<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]53release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]54web site</a>. If you have questions or comments, the <a
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]55href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
56Mailing List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]57
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]58<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]59main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +0000[diff] [blame]60current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]61<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]62
63</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]64
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]65
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]66<!--
67Almost dead code.
68 include/llvm/Analysis/LiveValues.h => Dan
69 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
70 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner00736fc2010-04-13 06:37:00 +0000[diff] [blame]71 ABCD, GEPSplitterPass
Chris Lattner048fe3c2010-01-16 21:25:13 +0000[diff] [blame]72 MSIL backend?
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]73 lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]74-->
75
76
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]77<!-- Features that need text if they're finished for 2.7:
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]78 combiner-aa?
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]79 strong phi elim
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]80 llvm.dbg.value: variable debug info for optimized code
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]81 loop dependence analysis
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]82 -->
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]83
Chris Lattner547a3912008-10-12 19:47:48 +0000[diff] [blame]84 <!-- for announcement email:
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]85 Logo web page.
86 llvm devmtg
87 compiler_rt
88 KLEE web page at klee.llvm.org
89 Many new papers added to /pubs/
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]90 Mention gcc plugin.
Chris Lattner74c80df2009-02-25 06:34:50 +0000[diff] [blame]91 -->
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]92
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]93<!-- *********************************************************************** -->
94<div class="doc_section">
95 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]96</div>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]97<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]98
99<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]100<p>
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]101The LLVM 2.7 distribution currently consists of code from the core LLVM
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]102repository (which roughly includes the LLVM optimizers, code generators
103and supporting tools), the Clang repository and the llvm-gcc repository. In
104addition to this code, the LLVM Project includes other sub-projects that are in
105development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +0000[diff] [blame]106</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]107
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]108</div>
109
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]110
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]111<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]112<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]113<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]114</div>
115
116<div class="doc_text">
117
Douglas Gregorf720a4e2010-04-22 20:42:40 +0000[diff] [blame]118<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C, C++, and Objective-C languages. Clang aims to provide a better user experience through expressive diagnostics, a high level of conformance to language standards, fast compilation, and low memory use. Like LLVM, Clang provides a modular, library-based architecture that makes it suitable for creating or integrating with other development tools. Clang is considered a production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]119
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]120<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000[diff] [blame]121
Daniel Dunbar13739432008-10-14 23:25:09 +0000[diff] [blame]122<ul>
Douglas Gregorf720a4e2010-04-22 20:42:40 +0000[diff] [blame]123
124<li>C++ Support: Clang is now capable of self-hosting! While still alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang, and C++ is now enabled by default. See the <a href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility page</a> for common C++ migration issues.</li>
125
David Chisnall8e0bd802010-04-25 19:13:33 +0000[diff] [blame]126<li>Objective-C: Clang now includes experimental support for an updated Objective-C ABI on non-Darwin platforms. This includes support for non-fragile instance variables and accelerated proxies, as well as greater potential for future optimisations. The new ABI is used when compiling with the -fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these options may be mixed with code compiled with GCC or clang using the old GNU ABI, but requires the libobjc2 runtime from the GNUstep project.</li>
127
Douglas Gregorf720a4e2010-04-22 20:42:40 +0000[diff] [blame]128<li>New warnings: Clang contains a number of new warnings, including control-flow warnings (unreachable code, missing return statements in a non-<code>void</code> function, etc.), sign-comparison warnings, and improved format-string warnings.</li>
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]129
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]130<li>CIndex API and Python bindings: Clang now includes a C API as part of the
Gabor Greif1440dbe2010-04-25 21:27:54 +0000[diff] [blame]131CIndex library. Although we may make some changes to the API in the future, it
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]132is intended to be stable and has been designed for use by external projects. See
133the Clang
134doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
Wesley Peck1f433612010-04-22 14:19:00 +0000[diff] [blame]135documentation for more details. The CIndex API also includes a preliminary
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]136set of Python bindings.</li>
137
138<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
139ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
Gabor Greif1440dbe2010-04-25 21:27:54 +0000[diff] [blame]140suitable for use as a beta quality ARM compiler.</li>
David Chisnall8e0bd802010-04-25 19:13:33 +0000[diff] [blame]141
Bill Wendling6bc15282009-03-02 04:28:18 +0000[diff] [blame]142</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]143</div>
144
145<!--=========================================================================-->
146<div class="doc_subsection">
147<a name="clangsa">Clang Static Analyzer</a>
148</div>
149
150<div class="doc_text">
151
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]152<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
153 project is an effort to use static source code analysis techniques to
154 automatically find bugs in C and Objective-C programs (and hopefully <a
155 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
156 future</a>!). The tool is very good at finding bugs that occur on specific
157 paths through code, such as on error conditions.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]158
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]159<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
160 minor improvements, including better support for tracking the fields of
161 structures, initial support (not enabled by default yet) for doing
162 interprocedural (cross-function) analysis, and new checks have been added.
163</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]164
165</div>
166
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]167<!--=========================================================================-->
168<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]169<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]170</div>
171
172<div class="doc_text">
173<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]174The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]175a JVM and a CLI Virtual Machine (Microsoft .NET is an
176implementation of the CLI) using LLVM for static and just-in-time
177compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]178
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]179<p>
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]180With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
181virtual machines. VMKit now offers precise and efficient garbage collection with
182multi-threading support, thanks to the MMTk memory management toolkit, as well
183as just in time and ahead of time compilation with LLVM. The major changes in
184VMKit 0.27 are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]185
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]186<ul>
187
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]188<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
189 The first collector to be ported is the MarkSweep collector, which is precise,
190 and drastically improves the performance of VMKit.</li>
191<li>Line number information in the JVM: by using the debug metadata of LLVM, the
192 JVM now supports precise line number information, useful when printing a stack
193 trace.</li>
194<li>Interface calls in the JVM: we implemented a variant of the Interface Method
195 Table technique for interface calls in the JVM.
196</li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]197
198</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]199</div>
200
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]201
202<!--=========================================================================-->
203<div class="doc_subsection">
204<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
205</div>
206
207<div class="doc_text">
208<p>
209The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
210is a simple library that provides an implementation of the low-level
211target-specific hooks required by code generation and other runtime components.
212For example, when compiling for a 32-bit target, converting a double to a 64-bit
213unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
214function. The compiler-rt library provides highly optimized implementations of
215this and other low-level routines (some are 3x faster than the equivalent
216libgcc routines).</p>
217
218<p>
219All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]220License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
221supports ARM targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]222
223</div>
224
225<!--=========================================================================-->
226<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]227<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]228</div>
229
230<div class="doc_text">
231<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]232<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
233gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
234gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
235whatsoever (currently one small patch is needed). This is thanks to the new
236<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
237makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
238which is nothing more than a dynamic library which conforms to the gcc plugin
239interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
240instead of the gcc optimizers, and the LLVM code generators instead of the gcc
241code generators, just like llvm-gcc. To use it, you add
242"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
243becomes llvm-gcc-4.5!
244</p>
245
246<p>
247DragonEgg is still a work in progress. Currently C works very well, while C++,
248Ada and Fortran work fairly well. All other languages either don't work at all,
249or only work poorly. For the moment only the x86-32 and x86-64 targets are
Duncan Sands51a51742010-04-20 19:40:58 +0000[diff] [blame]250supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]251</p>
252
253<p>
Duncan Sandscb9dda62010-04-21 13:51:48 +0000[diff] [blame]254DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]255</p>
256
257</div>
258
259
260<!--=========================================================================-->
261<div class="doc_subsection">
262<a name="mc">llvm-mc: Machine Code Toolkit</a>
263</div>
264
265<div class="doc_text">
266<p>
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]267The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
268of problems in the realm of assembly, disassembly, object file format handling,
269and a number of other related areas that CPU instruction-set level tools work
270in. It is a sub-project of LLVM which provides it with a number of advantages
271over other compilers that do not have tightly integrated assembly-level tools.
272For a gentle introduction, please see the <a
273href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
274LLVM MC Project Blog Post</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]275</p>
276
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]277<p>2.7 includes major parts of the work required by the new MC Project. A few
278 targets have been refactored to support it, and work is underway to support a
Gabor Greife32adf52010-04-25 21:30:22 +0000[diff] [blame]279 native assembler in LLVM. This work is not complete in LLVM 2.7, but it has
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]280 made substantially more progress on LLVM mainline.</p>
281
282<p>One minor example of what MC can do is to transcode an AT&amp;T syntax
Gabor Greifed387452010-04-22 10:25:23 +0000[diff] [blame]283 X86 .s file into intel syntax. You can do this with something like:</p>
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]284<pre>
285 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
286</pre>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]287
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]288</div>
289
290
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]291<!-- *********************************************************************** -->
292<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]293 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]294</div>
295<!-- *********************************************************************** -->
296
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]297<div class="doc_text">
298
299<p>An exciting aspect of LLVM is that it is used as an enabling technology for
300 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]301 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]302</div>
303
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]304<!--=========================================================================-->
305<div class="doc_subsection">
306<a name="pure">Pure</a>
307</div>
308
309<div class="doc_text">
310<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]311<a href="http://pure-lang.googlecode.com/">Pure</a>
312is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]313Programs are collections of equations which are used to evaluate expressions in
314a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]315lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]316built-in list and matrix support (including list and matrix comprehensions) and
317an easy-to-use C interface. The interpreter uses LLVM as a backend to
318 JIT-compile Pure programs to fast native code.</p>
319
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]320<p>Pure versions 0.43 and later have been tested and are known to work with
321LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
322
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]323</div>
324
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]325<!--=========================================================================-->
326<div class="doc_subsection">
327<a name="RoadsendPHP">Roadsend PHP</a>
328</div>
329
330<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]331<p>
332<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]333source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]334language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]335reimplementation of an earlier project that is now based on LLVM.
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]336</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]337</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]338
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]339<!--=========================================================================-->
340<div class="doc_subsection">
341<a name="UnladenSwallow">Unladen Swallow</a>
342</div>
343
344<div class="doc_text">
345<p>
346<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
347branch of <a href="http://python.org/">Python</a> intended to be fully
348compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerb5f6feb2010-03-18 06:52:15 +0000[diff] [blame]349compiler.
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]350</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]351</div>
352
353<!--=========================================================================-->
354<div class="doc_subsection">
Chris Lattner8d4bbbe2010-03-29 17:50:39 +0000[diff] [blame]355<a name="tce">TTA-based Codesign Environment (TCE)</a>
356</div>
357
358<div class="doc_text">
359<p>
360<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
361application-specific processors (ASP) based on the Transport triggered
362architecture (TTA). The toolset provides a complete co-design flow from C/C++
363programs down to synthesizable VHDL and parallel program binaries. Processor
364customization points include the register files, function units, supported
365operations, and the interconnection network.</p>
366
367<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
368independent optimizations and also for parts of code generation. It generates
369new LLVM-based code generators "on the fly" for the designed TTA processors and
370loads them in to the compiler backend as runtime libraries to avoid per-target
371recompilation of larger parts of the compiler chain.</p>
372
373</div>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]374
John Criswellf77cdab2010-04-06 14:52:14 +0000[diff] [blame]375<!--=========================================================================-->
376<div class="doc_subsection">
377<a name="safecode">SAFECode Compiler</a>
378</div>
379
380<div class="doc_text">
381<p>
382<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
383compiler built using LLVM. It takes standard, unannotated C code, analyzes the
384code to ensure that memory accesses and array indexing operations are safe, and
385instruments the code with run-time checks when safety cannot be proven
386statically.
387</p>
388</div>
389
Chris Lattnerfb1a7392010-04-22 17:28:36 +0000[diff] [blame]390<!--=========================================================================-->
391<div class="doc_subsection">
392<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
393</div>
John Criswellf77cdab2010-04-06 14:52:14 +0000[diff] [blame]394
Chris Lattnerfb1a7392010-04-22 17:28:36 +0000[diff] [blame]395<div class="doc_text">
396<p>
397<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
398harness to build OpenJDK using only free software build tools and to provide
399replacements for the not-yet free parts of OpenJDK. One of the extensions that
400IcedTea provides is a new JIT compiler named <a
401href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
402to provide native code generation without introducing processor-dependent
403code.
404</p>
405<p>Icedtea6 1.8 and later have been tested and are known to work with
406LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
407</p>
408</div>
409
410<!--=========================================================================-->
411<div class="doc_subsection">
412<a name="llvm-lua">LLVM-Lua</a>
413</div>
414
415<div class="doc_text">
416<p>
417<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
418 to add JIT and static compiling support to the Lua VM. Lua
419bytecode is analyzed to remove type checks, then LLVM is used to compile the
420bytecode down to machine code.
421</p>
422<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
423</p>
424</div>
Chris Lattner3a1d4cf2010-04-22 21:34:16 +0000[diff] [blame]425
426<!--=========================================================================-->
427<div class="doc_subsection">
428<a name="MacRuby">MacRuby</a>
429</div>
430
431<div class="doc_text">
432<p>
433<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on
434core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for
435optimization passes, JIT compilation and exception handling. It also allows
436static (ahead-of-time) compilation of Ruby code straight to machine code.
437</p>
438<p>The upcoming MacRuby 0.6 release works with LLVM 2.7.
439</p>
440</div>
441
Chris Lattner7c8e7962010-04-26 17:38:10 +0000[diff] [blame^]442<!--=========================================================================-->
443<div class="doc_subsection">
444<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
445</div>
446
447<div class="doc_text">
448<p>
449<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
450state-of-the-art programming suite for Haskell, a standard lazy
451functional programming language. It includes an optimizing static
452compiler generating good code for a variety of platforms, together
453with an interactive system for convenient, quick development.</p>
454
455<p>In addition to the existing C and native code generators, GHC now
456supports an <a
457href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
458code generator</a>. GHC supports LLVM 2.7.</p>
459
460</div>
461
Chris Lattner3a1d4cf2010-04-22 21:34:16 +0000[diff] [blame]462
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]463<!-- *********************************************************************** -->
464<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]465 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]466</div>
467<!-- *********************************************************************** -->
468
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]469<div class="doc_text">
470
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]471<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]472minor improvements. Some of the major improvements and new features are listed
473in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]474</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]475
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]476</div>
477
478<!--=========================================================================-->
479<div class="doc_subsection">
480<a name="orgchanges">LLVM Community Changes</a>
481</div>
482
483<div class="doc_text">
484
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]485<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
486organization changes have happened:
487</p>
488
489<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]490<li>LLVM has a new <a href="http://llvm.org/Logo.html">official logo</a>!</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]491
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]492<li>Ted Kremenek and Doug Gregor have stepped forward as <a
493 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]494 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]495
496<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
497 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
498 to learn about new LLVM-related features as they are implemented. Several
499 features in this release are already explained on the blog.</li>
500
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]501<li>The LLVM web pages are now checked into the SVN server, in the "www",
502 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]503 largely inaccessible old CVS server.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]504
505<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
506 faster) server. It is still graciously hosted at the University of Illinois
507 of Urbana Champaign.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]508</ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]509</div>
510
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]511<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]512<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]513<a name="majorfeatures">Major New Features</a>
514</div>
515
516<div class="doc_text">
517
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]518<p>LLVM 2.7 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]519
520<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]521<li>2.7 includes initial support for the <a
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]522 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
523 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]524
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]525<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]526 supports many different use cases, including allowing front-end authors to
527 encode source level information into LLVM IR, which is consumed by later
528 language-specific passes. This is a great way to do high-level optimizations
529 like devirtualization, type-based alias analysis, etc. See the <a
530 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
531 Extensible Metadata Blog Post</a> for more information.</li>
532
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]533<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]534in a completely new way, built on extensible metadata. The new implementation
535is much more memory efficient and paves the way for improvements to optimized
536code debugging experience.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]537
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]538<li>2.7 now directly supports taking the address of a label and doing an
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]539 indirect branch through a pointer. This is particularly useful for
540 interpreter loops, and is used to implement the GCC "address of label"
541 extension. For more information, see the <a
542href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
543Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]544
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]545<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]546 disassembling target machine code. These APIs are useful for a variety of
547 low level clients, and are surfaced in the new "enhanced disassembly" API.
548 For more information see the <a
549 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
550 Disassembler Blog Post</a> for more information.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]551
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]552<li>2.7 includes major parts of the work required by the new MC Project,
553 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]554
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]555</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]556
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]557</div>
558
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]559<!--=========================================================================-->
560<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]561<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]562</div>
563
564<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]565<p>LLVM IR has several new features for better support of new targets and that
566expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]567
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]568<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]569<li>LLVM IR now supports a 16-bit "half float" data type through <a
570 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
571<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]572 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]573 optimizer that a function was declared 'inline' and thus the inliner should
574 weight it higher when considering inlining it. The later
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]575 indicates to the code generator that the function diverges from the platform
576 ABI on stack alignment.</li>
577<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
578 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]579 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]580 extension.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]581<li>LLVM IR now supports marking load and store instructions with <a
582 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
583 metadata feature). This hint encourages the code
584 generator to generate non-temporal accesses when possible, which are useful
585 for code that is carefully managing cache behavior. Currently, only the
586 X86 backend provides target support for this feature.</li>
587
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]588<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifc8b3af92010-04-22 10:11:24 +0000[diff] [blame]589 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]590 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]591 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Gabor Greifee2187a2010-04-22 10:21:43 +0000[diff] [blame]592
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]593</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]594
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]595</div>
596
597<!--=========================================================================-->
598<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]599<a name="optimizer">Optimizer Improvements</a>
600</div>
601
602<div class="doc_text">
603
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]604<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]605release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]606
607<ul>
608
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]609<li>The inliner reuses now merges arrays stack objects in different callees when
610 inlining multiple call sites into one function. This reduces the stack size
611 of the resultant function.</li>
612<li>The -basicaa alias analysis pass (which is the default) has been improved to
613 be less dependent on "type safe" pointers. It can now look through bitcasts
614 and other constructs more aggressively, allowing better load/store
615 optimization.</li>
616<li>The load elimination optimization in the GVN Pass [<a
617href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
618 blog post</a>] has been substantially improved to be more aggressive about
619 partial redundancy elimination and do more aggressive phi translation. Please
620 see the <a
621 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
622 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
623 Blog Post</a> for more details.</li>
624<li>The module <a href="LangRef.html#datalayout">target data string</a> now
Wesley Peck68d1fe92010-04-22 13:28:34 +0000[diff] [blame]625 includes a notion of 'native' integer data types for the target. This
626 helps mid-level optimizations avoid promoting complex sequences of
627 operations to data types that are not natively supported (e.g. converting
628 i32 operations to i64 on 32-bit chips).</li>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]629<li>The mid-level optimizer is now conservative when operating on a module with
630 no target data. Previously, it would default to SparcV9 settings, which is
631 not what most people expected.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]632<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]633 conditionals and threading blocks with otherwise complex logic. It has
634 subsumed the old "Conditional Propagation" pass, and -condprop has been
635 removed from LLVM 2.7.</li>
636<li>The -instcombine pass has been refactored from being one huge file to being
637 a library of its own. Internally, it uses a customized IRBuilder to clean
638 it up and simplify it.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]639
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]640<li>The optimal edge profiling pass is reliable and much more complete than in
641 2.6. It can be used with the llvm-prof tool but isn't wired up to the
642 llvm-gcc and clang command line options yet.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]643
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]644<li>A new experimental alias analysis implementation, -scev-aa, has been added.
645 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
646 pointer offset expressions to disambiguate pointers. It can catch a few
647 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]648
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]649<li>The default pass ordering has been tweaked for improved optimization
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]650 effectiveness.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]651
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]652</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]653
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]654</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]655
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]656
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]657<!--=========================================================================-->
658<div class="doc_subsection">
659<a name="executionengine">Interpreter and JIT Improvements</a>
660</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]661
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]662<div class="doc_text">
663
664<ul>
Wesley Peck640604a2010-04-22 13:36:27 +0000[diff] [blame]665<li>The JIT now supports generating debug information and is compatible with
666the new GDB 7.0 (and later) interfaces for registering dynamically generated
667debug info.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]668
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]669<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin01eba392010-01-29 19:10:38 +0000[diff] [blame]670to compiling eagerly</a> to avoid a race condition in the lazy JIT.
671Clients that still want the lazy JIT can switch it on by calling
672<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]673
Jeffrey Yasskin40966a72010-02-11 01:07:39 +0000[diff] [blame]674<li>It is now possible to create more than one JIT instance in the same process.
675These JITs can generate machine code in parallel,
676although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
677still have to obey the other threading restrictions</a>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]678
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]679</ul>
680
681</div>
682
683<!--=========================================================================-->
684<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]685<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]686</div>
687
688<div class="doc_text">
689
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]690<p>We have put a significant amount of work into the code generator
691infrastructure, which allows us to implement more aggressive algorithms and make
692it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]693
694<ul>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]695<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
696 to emit many useful comments to .s files indicating information about spill
697 slots and loop nest structure. This should make it much easier to read and
698 understand assembly files. This is wired up in llvm-gcc and clang to
699 the <tt>-fverbose-asm</tt> option.</li>
700
Dan Gohman9c675f12010-04-22 20:50:43 +0000[diff] [blame]701<li>New LSR with "full strength reduction" mode, which can reduce address
702 register pressure in loops where address generation is important.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]703
704<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
705 is available and enabled by default. It catches redundancies exposed by
706 lowering.</li>
707<li>A new pre-register-allocation tail duplication pass is available and enabled
708 by default, it can substantially improve branch prediction quality in some
709 cases.</li>
710<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
711 is available and enabled by default. This pass can takes advantage
712 architecture features like x86-64 implicit zero extension behavior and
713 sub-registers.</li>
714<li>The code generator now supports a mode where it attempts to preserve the
715 order of instructions in the input code. This is important for source that
716 is hand scheduled and extremely sensitive to scheduling. It is compatible
717 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
718<li>The target-independent code generator now supports generating code with
719 arbitrary numbers of result values. Returning more values than was
720 previously supported is handled by returning through a hidden pointer. In
721 2.7, only the X86 and XCore targets have adopted support for this
722 though.</li>
723<li>The code generator now supports generating code that follows the
724 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
725 Convention</a> and ABI.</li>
726<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
727 selection</a>" phase of the code generator has been largely rewritten for
728 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
729 linked into the target to do the pattern matching, now it emits a much
730 smaller table which is read by the target-independent code. The primary
731 advantages of this approach is that the size and compile time of various
732 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
733 for example.</li>
734<li>Almost the entire code generator has switched to emitting code through the
735 MC interfaces instead of printing textually to the .s file. This led to a
736 number of cleanups and speedups. In 2.7, debug an exception handling
737 information does not go through MC yet.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]738</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]739</div>
740
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]741<!--=========================================================================-->
742<div class="doc_subsection">
743<a name="x86">X86-32 and X86-64 Target Improvements</a>
744</div>
745
746<div class="doc_text">
747<p>New features of the X86 target include:
748</p>
749
750<ul>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]751<li>The X86 backend now optimizes tails calls much more aggressively for
752 functions that use the standard C calling convention.</li>
753<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
754 registers, making the code generator more aggressive in cases where scalars
755 and vector types are mixed.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]756
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]757</ul>
758
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]759</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]760
761<!--=========================================================================-->
762<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]763<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]764</div>
765
766<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]767<p>New features of the ARM target include:
768</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]769
770<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]771
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]772<li>The ARM backend now generates instructions in unified assembly syntax.</li>
773
774<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
775 support differs slightly from the GCC implementation. Please see the
776 <a
777href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
778 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
779 helpful information if migrating code from GCC to LLVM-GCC.</li>
780
Wesley Peck9e385b12010-04-22 13:43:14 +0000[diff] [blame]781<li>The ARM and Thumb code generators now use register scavenging for stack
Jim Grosbach269e0fe2010-04-22 18:28:43 +0000[diff] [blame]782 object address materialization. This allows the use of R3 as a general
783 purpose register in Thumb1 code, as it was previous reserved for use in
784 stack address materialization. Secondly, sequential uses of the same
785 value will now re-use the materialized constant.</li>
786
Wesley Peck9e385b12010-04-22 13:43:14 +0000[diff] [blame]787<li>The ARM backend now has good support for ARMv4 targets and has been tested
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]788 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
789 newer chips.</li>
Jim Grosbach41a77662010-04-22 18:33:31 +0000[diff] [blame]790
791<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize,
792 __sync_fetch_and_add, etc.).</li>
793
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]794</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]795
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]796
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]797</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]798
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]799<!--=========================================================================-->
800<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]801<a name="newapis">New Useful APIs</a>
802</div>
803
804<div class="doc_text">
805
806<p>This release includes a number of new APIs that are used internally, which
807 may also be useful for external clients.
808</p>
809
810<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]811<li>The optimizer uses the new CodeMetrics class to measure the size of code.
Chris Lattner83cd35a2010-04-22 17:39:38 +0000[diff] [blame]812 Various passes (like the inliner, loop unswitcher, etc) all use this to make
813 more accurate estimates of the code size impact of various
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]814 optimizations.</li>
815<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
Wesley Peckc0287ba2010-04-22 13:50:46 +0000[diff] [blame]816 llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]817 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
818 without requiring the instruction to exist. This centralizes a lot of
819 ad-hoc symbolic manipulation code scattered in various passes.</li>
820<li>The optimizer now uses a new <a
821 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
822 class which efficiently supports
823 doing unstructured SSA update operations. This centralized a bunch of code
Wesley Peckc0287ba2010-04-22 13:50:46 +0000[diff] [blame]824 scattered throughout various passes (e.g. jump threading, lcssa,
825 loop rotate, etc) for doing this sort of thing. The code generator has a
826 similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]827 MachineSSAUpdater</a> class.</li>
828<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
829 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]830 expression API. Building on this, the <a
831 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
832 regular exressions.</li>
833<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
834 By default, this stream works the same way as "errs()", but if you pass
835 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
836 fixed sized circular buffer and the output is printed at the end of the
837 program's execution. This is helpful if you have a long lived compiler
838 process and you're interested in seeing snapshots in time.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]839</ul>
840
841
842</div>
843
844<!--=========================================================================-->
845<div class="doc_subsection">
846<a name="otherimprovements">Other Improvements and New Features</a>
847</div>
848
849<div class="doc_text">
850<p>Other miscellaneous features include:</p>
851
852<ul>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]853<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
854 get this, configure LLVM with the --enable-shared option.</li>
855
Wesley Pecka0c44842010-04-22 13:53:54 +0000[diff] [blame]856<li>LLVM command line tools now overwrite their output by default. Previously,
857 they would only do this with -f. This makes them more convenient to use, and
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]858 behave more like standard unix tools.</li>
859
860<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
861 file, and automatically do the right thing. This means you don't need to
862 explicitly use the llvm-as tool for most things.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]863</ul>
864
865</div>
866
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]867
868<!--=========================================================================-->
869<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]870<a name="changes">Major Changes and Removed Features</a>
871</div>
872
873<div class="doc_text">
874
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]875<p>If you're already an LLVM user or developer with out-of-tree changes based
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]876on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]877from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]878
879<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]880
881<li>
882The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
883("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
884profiling ("rsprofiling") passes have all been removed. They were not being
885actively maintained and had substantial problems. If you are interested in
886these components, you are welcome to ressurect them from SVN, fix the
887correctness problems, and resubmit them to mainline.</li>
888
889<li>LLVM now defaults to building most libraries with RTTI turned off, providing
890a code size reduction. Packagers who are interested in building LLVM to support
891plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
892and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
893document.</li>
894
Jeffrey Yasskinbc83d062010-02-09 23:03:44 +0000[diff] [blame]895<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
896if you have it installed. This makes it more likely that an LLVM built on one
897system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]898configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]899
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]900<li>Debug information uses a completely different representation, an LLVM 2.6
901.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
902
903<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
904 along with LowerAllocations pass. Now you should just use a call to the
905 malloc and free functions in libc. These calls are optimized as well as
906 the old instructions were.</li>
907</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]908
909<p>In addition, many APIs have changed in this release. Some of the major LLVM
910API changes are:</p>
911
912<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]913<li>Just about everything has been converted to use raw_ostream instead of
914 std::ostream.</li>
915<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
916 instead.</li>
917<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
918 instead.</li>
Chris Lattnercd062cd2010-04-22 17:25:00 +0000[diff] [blame]919<li>The TargetAsmInfo interface was renamed to MCAsmInfo.</li>
Jeffrey Yasskin4fcd6072010-01-28 01:41:20 +0000[diff] [blame]920<li><tt>ModuleProvider</tt> has been <a
Gabor Greifee2187a2010-04-22 10:21:43 +0000[diff] [blame]921href="http://llvm.org/viewvc/llvm-project?view=rev&amp;revision=94686">removed</a>
Jeffrey Yasskin4fcd6072010-01-28 01:41:20 +0000[diff] [blame]922and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
923Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
924replace <tt>getBitcodeModuleProvider</tt> with
925<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
926functions that used to accept <tt>ModuleProvider</tt>. Clients who
927wrote their own <tt>ModuleProvider</tt>s will need to derive from
928<tt>GVMaterializer</tt> instead and use
929<tt>Module::setMaterializer</tt> to attach it to a
930<tt>Module</tt>.</li>
931
932<li><tt>GhostLinkage</tt> has given up the ghost.
933<tt>GlobalValue</tt>s that have not yet been read from their backing
934storage have the same linkage they will have after being read in.
935Clients must replace calls to
936<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
937<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar4acdede2010-02-10 04:09:52 +0000[diff] [blame]938
Duncan Sands411432d2010-02-17 17:20:17 +0000[diff] [blame]939<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
940<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
941<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
942<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Chris Lattnercd062cd2010-04-22 17:25:00 +0000[diff] [blame]943
944<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
945<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
946 booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
947<li>Some header files have been renamed:
948<ul>
949 <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
950 <tt>llvm/System/AIXDataTypesFix.h</tt></li>
951 <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
952 <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
953 <tt>llvm/Analysis/InlineCost.h</tt></li>
954 <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
955 <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
956</ul></li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]957</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]958
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]959</div>
960
961
962
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]963<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]964<div class="doc_section">
965 <a name="portability">Portability and Supported Platforms</a>
966</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]967<!-- *********************************************************************** -->
968
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]969<div class="doc_text">
970
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]971<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]972
973<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]974<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]975 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
976 systems).</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]977<li>PowerPC and X86-based Mac OS X systems, running 10.4 and above in 32-bit
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]978 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]979<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]980<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
981 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]982<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]983<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]984</ul>
985
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]986<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]987to the machine and operating system on which it is built. However, minor
988porting may be required to get LLVM to work on new platforms. We welcome your
989portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]990
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]991</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]992
993<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]994<div class="doc_section">
995 <a name="knownproblems">Known Problems</a>
996</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]997<!-- *********************************************************************** -->
998
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]999<div class="doc_text">
1000
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1001<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1002listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1003href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1004there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1005
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]1006<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1007<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
1008using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]1009See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1010However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
1011for x86/x86-64 has been made available from the third party AuroraUX Project
1012that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
1013</ul>
1014
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1015</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1016
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1017<!-- ======================================================================= -->
1018<div class="doc_subsection">
1019 <a name="experimental">Experimental features included with this release</a>
1020</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1021
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1022<div class="doc_text">
1023
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]1024<p>The following components of this LLVM release are either untested, known to
1025be broken or unreliable, or are in early development. These components should
1026not be relied on, and bugs should not be filed against them, but they may be
1027useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1028components, please contact us on the <a
1029href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1030
1031<ul>
Wesley Peck7c4a1212010-03-18 14:31:30 +0000[diff] [blame]1032<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
1033 backends are experimental.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]1034<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]1035 supported value for this option. The MachO writer is experimental, and
1036 works much better in mainline SVN.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1037</ul>
1038
1039</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1040
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1041<!-- ======================================================================= -->
1042<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1043 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1044</div>
1045
1046<div class="doc_text">
1047
1048<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1049 <li>The X86 backend does not yet support
1050 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1051 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1052 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1053 <li>The X86 backend generates inefficient floating point code when configured
1054 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]1055 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1056 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]1057 runtime currently due to lack of support for the 'u' inline assembly
1058 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1059 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]1060 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1061 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1062</ul>
1063
1064</div>
1065
1066<!-- ======================================================================= -->
1067<div class="doc_subsection">
1068 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1069</div>
1070
1071<div class="doc_text">
1072
1073<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]1074<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1075compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1076</ul>
1077
1078</div>
1079
1080<!-- ======================================================================= -->
1081<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1082 <a name="arm-be">Known problems with the ARM back-end</a>
1083</div>
1084
1085<div class="doc_text">
1086
1087<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1088<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]1089processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1090results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1091<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1092</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1093</ul>
1094
1095</div>
1096
1097<!-- ======================================================================= -->
1098<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1099 <a name="sparc-be">Known problems with the SPARC back-end</a>
1100</div>
1101
1102<div class="doc_text">
1103
1104<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1105<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1106 support the 64-bit SPARC ABI (-m64).</li>
1107</ul>
1108
1109</div>
1110
1111<!-- ======================================================================= -->
1112<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1113 <a name="mips-be">Known problems with the MIPS back-end</a>
1114</div>
1115
1116<div class="doc_text">
1117
1118<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1119<li>64-bit MIPS targets are not supported yet.</li>
1120</ul>
1121
1122</div>
1123
1124<!-- ======================================================================= -->
1125<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1126 <a name="alpha-be">Known problems with the Alpha back-end</a>
1127</div>
1128
1129<div class="doc_text">
1130
1131<ul>
1132
1133<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1134appropriate nops inserted to ensure restartability.</li>
1135
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1136</ul>
1137</div>
1138
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1139<!-- ======================================================================= -->
1140<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1141 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1142</div>
1143
1144<div class="doc_text">
1145
1146<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1147<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1148 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1149<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1150 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1151 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1152<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1153<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1154</ul>
1155
1156</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1157
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1158
1159<!-- ======================================================================= -->
1160<div class="doc_subsection">
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]1161 <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1162</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1163
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1164<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1165
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1166<p>The only major language feature of GCC not supported by llvm-gcc is
1167 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1168 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1169 supported on some targets (these are used when you take the address of a
1170 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1171
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1172</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1173
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1174<!-- ======================================================================= -->
1175<div class="doc_subsection">
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1176 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1177</div>
1178
1179<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1180<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1181<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1182 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1183 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1184</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1185</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1186
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1187<!-- ======================================================================= -->
1188<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1189 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1190</div>
1191
1192<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1193The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1194technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1195<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1196<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1197to lack of trampoline support (pointers to nested functions) on other platforms.
1198However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1199which does support trampolines.</li>
1200<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1201This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1202exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1203Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1204<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1205and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1206(c380004 also fails with gcc-4.2 mainline).
1207If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1208causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1209<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1210<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1211<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1212crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1213<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1214or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1215or use representation clauses that result in a field of a non-discrete type
1216starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1217<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1218'main' as generated by the Ada binder to be invalid</a>.
1219Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1220<tt>envp</tt> rather than integers.</li>
1221<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1222ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1223</ul>
1224</div>
1225
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1226<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1227<div class="doc_section">
1228 <a name="additionalinfo">Additional Information</a>
1229</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1230<!-- *********************************************************************** -->
1231
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1232<div class="doc_text">
1233
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1234<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1235href="http://llvm.org">LLVM web page</a>, in particular in the <a
1236href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1237contains versions of the API documentation which is up-to-date with the
1238Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1239You can access versions of these documents specific to this release by going
1240into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1241
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1242<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1243us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1244lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1245
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1246</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1247
1248<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1249
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1250<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1251<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1252 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1253 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1254 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1255 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1256
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1257 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1258 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1259</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1260
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1261</body>
1262</html>