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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 8cdd7939ad29c0424da18e3456797b5c83c1f387 / . / 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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3<html>
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"
14 width="136" height="136">
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
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]118<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</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>
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]123<li>FIXME: C++! Include a link to cxx_compatibility.html</li>
124
125<li>FIXME: Static Analyzer improvements?</li>
126
127<li>CIndex API and Python bindings: Clang now includes a C API as part of the
128CIndex library. Although we make make some changes to the API in the future, it
129is intended to be stable and has been designed for use by external projects. See
130the Clang
131doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
132documentation for more details. The CIndex API also includings an preliminary
133set of Python bindings.</li>
134
135<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
136ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
137suitable for use as a a beta quality ARM compiler.</li>
Bill Wendling6bc15282009-03-02 04:28:18 +0000[diff] [blame]138</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]139</div>
140
141<!--=========================================================================-->
142<div class="doc_subsection">
143<a name="clangsa">Clang Static Analyzer</a>
144</div>
145
146<div class="doc_text">
147
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame^]148<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
149 project is an effort to use static source code analysis techniques to
150 automatically find bugs in C and Objective-C programs (and hopefully <a
151 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
152 future</a>!). The tool is very good at finding bugs that occur on specific
153 paths through code, such as on error conditions.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]154
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame^]155<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
156 minor improvements, including better support for tracking the fields of
157 structures, initial support (not enabled by default yet) for doing
158 interprocedural (cross-function) analysis, and new checks have been added.
159</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]160
161</div>
162
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]163<!--=========================================================================-->
164<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]165<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]166</div>
167
168<div class="doc_text">
169<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]170The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]171a JVM and a CLI Virtual Machine (Microsoft .NET is an
172implementation of the CLI) using LLVM for static and just-in-time
173compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]174
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]175<p>
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]176With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
177virtual machines. VMKit now offers precise and efficient garbage collection with
178multi-threading support, thanks to the MMTk memory management toolkit, as well
179as just in time and ahead of time compilation with LLVM. The major changes in
180VMKit 0.27 are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]181
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]182<ul>
183
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]184<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
185 The first collector to be ported is the MarkSweep collector, which is precise,
186 and drastically improves the performance of VMKit.</li>
187<li>Line number information in the JVM: by using the debug metadata of LLVM, the
188 JVM now supports precise line number information, useful when printing a stack
189 trace.</li>
190<li>Interface calls in the JVM: we implemented a variant of the Interface Method
191 Table technique for interface calls in the JVM.
192</li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]193
194</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]195</div>
196
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]197
198<!--=========================================================================-->
199<div class="doc_subsection">
200<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
201</div>
202
203<div class="doc_text">
204<p>
205The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
206is a simple library that provides an implementation of the low-level
207target-specific hooks required by code generation and other runtime components.
208For example, when compiling for a 32-bit target, converting a double to a 64-bit
209unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
210function. The compiler-rt library provides highly optimized implementations of
211this and other low-level routines (some are 3x faster than the equivalent
212libgcc routines).</p>
213
214<p>
215All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]216License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
217supports ARM targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]218
219</div>
220
221<!--=========================================================================-->
222<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]223<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]224</div>
225
226<div class="doc_text">
227<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]228<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
229gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
230gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
231whatsoever (currently one small patch is needed). This is thanks to the new
232<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
233makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
234which is nothing more than a dynamic library which conforms to the gcc plugin
235interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
236instead of the gcc optimizers, and the LLVM code generators instead of the gcc
237code generators, just like llvm-gcc. To use it, you add
238"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
239becomes llvm-gcc-4.5!
240</p>
241
242<p>
243DragonEgg is still a work in progress. Currently C works very well, while C++,
244Ada and Fortran work fairly well. All other languages either don't work at all,
245or 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]246supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]247</p>
248
249<p>
Duncan Sandscb9dda62010-04-21 13:51:48 +0000[diff] [blame]250DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]251</p>
252
253</div>
254
255
256<!--=========================================================================-->
257<div class="doc_subsection">
258<a name="mc">llvm-mc: Machine Code Toolkit</a>
259</div>
260
261<div class="doc_text">
262<p>
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame^]263The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
264of problems in the realm of assembly, disassembly, object file format handling,
265and a number of other related areas that CPU instruction-set level tools work
266in. It is a sub-project of LLVM which provides it with a number of advantages
267over other compilers that do not have tightly integrated assembly-level tools.
268For a gentle introduction, please see the <a
269href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
270LLVM MC Project Blog Post</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]271</p>
272
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame^]273<p>2.7 includes major parts of the work required by the new MC Project. A few
274 targets have been refactored to support it, and work is underway to support a
275 native assembler in LLVM. This work is not complete in LLVM 2.7, but you has
276 made substantially more progress on LLVM mainline.</p>
277
278<p>One minor example of what MC can do is to transcode an AT&amp;T syntax
279 X86 .s file into intel syntax. You can do this with something like:</p>
280
281<pre>
282 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
283</pre>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]284</p>
285
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]286</div>
287
288
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]289<!-- *********************************************************************** -->
290<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]291 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]292</div>
293<!-- *********************************************************************** -->
294
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]295<div class="doc_text">
296
297<p>An exciting aspect of LLVM is that it is used as an enabling technology for
298 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]299 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]300</div>
301
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]302<!--=========================================================================-->
303<div class="doc_subsection">
304<a name="pure">Pure</a>
305</div>
306
307<div class="doc_text">
308<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]309<a href="http://pure-lang.googlecode.com/">Pure</a>
310is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]311Programs are collections of equations which are used to evaluate expressions in
312a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]313lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]314built-in list and matrix support (including list and matrix comprehensions) and
315an easy-to-use C interface. The interpreter uses LLVM as a backend to
316 JIT-compile Pure programs to fast native code.</p>
317
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]318<p>Pure versions 0.43 and later have been tested and are known to work with
319LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
320
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]321</div>
322
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]323<!--=========================================================================-->
324<div class="doc_subsection">
325<a name="RoadsendPHP">Roadsend PHP</a>
326</div>
327
328<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]329<p>
330<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]331source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]332language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]333reimplementation of an earlier project that is now based on LLVM.
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]334</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]335</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]336
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]337<!--=========================================================================-->
338<div class="doc_subsection">
339<a name="UnladenSwallow">Unladen Swallow</a>
340</div>
341
342<div class="doc_text">
343<p>
344<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
345branch of <a href="http://python.org/">Python</a> intended to be fully
346compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerb5f6feb2010-03-18 06:52:15 +0000[diff] [blame]347compiler.
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]348</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]349</div>
350
351<!--=========================================================================-->
352<div class="doc_subsection">
Chris Lattner8d4bbbe2010-03-29 17:50:39 +0000[diff] [blame]353<a name="tce">TTA-based Codesign Environment (TCE)</a>
354</div>
355
356<div class="doc_text">
357<p>
358<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
359application-specific processors (ASP) based on the Transport triggered
360architecture (TTA). The toolset provides a complete co-design flow from C/C++
361programs down to synthesizable VHDL and parallel program binaries. Processor
362customization points include the register files, function units, supported
363operations, and the interconnection network.</p>
364
365<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
366independent optimizations and also for parts of code generation. It generates
367new LLVM-based code generators "on the fly" for the designed TTA processors and
368loads them in to the compiler backend as runtime libraries to avoid per-target
369recompilation of larger parts of the compiler chain.</p>
370
371</div>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]372
John Criswellf77cdab2010-04-06 14:52:14 +0000[diff] [blame]373<!--=========================================================================-->
374<div class="doc_subsection">
375<a name="safecode">SAFECode Compiler</a>
376</div>
377
378<div class="doc_text">
379<p>
380<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
381compiler built using LLVM. It takes standard, unannotated C code, analyzes the
382code to ensure that memory accesses and array indexing operations are safe, and
383instruments the code with run-time checks when safety cannot be proven
384statically.
385</p>
386</div>
387
388
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]389<!-- *********************************************************************** -->
390<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]391 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]392</div>
393<!-- *********************************************************************** -->
394
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]395<div class="doc_text">
396
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]397<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]398minor improvements. Some of the major improvements and new features are listed
399in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]400</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]401
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]402</div>
403
404<!--=========================================================================-->
405<div class="doc_subsection">
406<a name="orgchanges">LLVM Community Changes</a>
407</div>
408
409<div class="doc_text">
410
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]411<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
412organization changes have happened:
413</p>
414
415<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]416<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]417
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]418<li>Ted Kremenek and Doug Gregor have stepped forward as <a
419 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]420 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]421
422<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
423 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
424 to learn about new LLVM-related features as they are implemented. Several
425 features in this release are already explained on the blog.</li>
426
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]427<li>The LLVM web pages are now checked into the SVN server, in the "www",
428 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]429 largely inaccessible old CVS server.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]430
431<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
432 faster) server. It is still graciously hosted at the University of Illinois
433 of Urbana Champaign.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]434</ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]435</div>
436
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]437<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]438<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]439<a name="majorfeatures">Major New Features</a>
440</div>
441
442<div class="doc_text">
443
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]444<p>LLVM 2.7 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]445
446<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]447<li>2.7 includes initial support for the <a
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]448 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
449 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]450
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]451<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]452 supports many different use cases, including allowing front-end authors to
453 encode source level information into LLVM IR, which is consumed by later
454 language-specific passes. This is a great way to do high-level optimizations
455 like devirtualization, type-based alias analysis, etc. See the <a
456 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
457 Extensible Metadata Blog Post</a> for more information.</li>
458
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]459<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]460in a completely new way, built on extensible metadata. The new implementation
461is much more memory efficient and paves the way for improvements to optimized
462code debugging experience.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]463
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]464<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]465 indirect branch through a pointer. This is particularly useful for
466 interpreter loops, and is used to implement the GCC "address of label"
467 extension. For more information, see the <a
468href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
469Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]470
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]471<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]472 disassembling target machine code. These APIs are useful for a variety of
473 low level clients, and are surfaced in the new "enhanced disassembly" API.
474 For more information see the <a
475 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
476 Disassembler Blog Post</a> for more information.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]477
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame^]478<li>2.7 includes major parts of the work required by the new MC Project,
479 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]480</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]481
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]482</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]483
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]484</div>
485
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]486<!--=========================================================================-->
487<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]488<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]489</div>
490
491<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]492<p>LLVM IR has several new features for better support of new targets and that
493expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]494
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]495<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]496<li>LLVM IR now supports a 16-bit "half float" data type through <a
497 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
498<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]499 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]500 optimizer that a function was declared 'inline' and thus the inliner should
501 weight it higher when considering inlining it. The later
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]502 indicates to the code generator that the function diverges from the platform
503 ABI on stack alignment.</li>
504<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
505 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]506 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]507 extension.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]508<li>LLVM IR now supports marking load and store instructions with <a
509 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
510 metadata feature). This hint encourages the code
511 generator to generate non-temporal accesses when possible, which are useful
512 for code that is carefully managing cache behavior. Currently, only the
513 X86 backend provides target support for this feature.</li>
514
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]515<li>LLVM 2.7 has pre-alpha support for <a
516 href="http://llvm.org/docs/LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]517 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]518 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]519</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]520</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]521
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]522</div>
523
524<!--=========================================================================-->
525<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]526<a name="optimizer">Optimizer Improvements</a>
527</div>
528
529<div class="doc_text">
530
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]531<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]532release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]533
534<ul>
535
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]536<li>The inliner reuses now merges arrays stack objects in different callees when
537 inlining multiple call sites into one function. This reduces the stack size
538 of the resultant function.</li>
539<li>The -basicaa alias analysis pass (which is the default) has been improved to
540 be less dependent on "type safe" pointers. It can now look through bitcasts
541 and other constructs more aggressively, allowing better load/store
542 optimization.</li>
543<li>The load elimination optimization in the GVN Pass [<a
544href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
545 blog post</a>] has been substantially improved to be more aggressive about
546 partial redundancy elimination and do more aggressive phi translation. Please
547 see the <a
548 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
549 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
550 Blog Post</a> for more details.</li>
551<li>The module <a href="LangRef.html#datalayout">target data string</a> now
552 includes a notion of what the 'native' integer data types a for the target,
553 which allows various optimizations to use. This helps mid-level
554 optimizations avoid promoting complex sequences of operations to data types
555 that are not natively supported (e.g. converting i32 operations to i64 on
556 a 32-bit chip).</li>
557<li>The mid-level optimizer is now conservative when operating on a module with
558 no target data. Previously, it would default to SparcV9 settings, which is
559 not what most people expected.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]560<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]561 conditionals and threading blocks with otherwise complex logic. It has
562 subsumed the old "Conditional Propagation" pass, and -condprop has been
563 removed from LLVM 2.7.</li>
564<li>The -instcombine pass has been refactored from being one huge file to being
565 a library of its own. Internally, it uses a customized IRBuilder to clean
566 it up and simplify it.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]567
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]568<li>The optimal edge profiling pass is reliable and much more complete than in
569 2.6. It can be used with the llvm-prof tool but isn't wired up to the
570 llvm-gcc and clang command line options yet.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]571
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]572<li>A new experimental alias analysis implementation, -scev-aa, has been added.
573 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
574 pointer offset expressions to disambiguate pointers. It can catch a few
575 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]576
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]577<li>The default pass ordering has been tweaked for improved optimization
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]578 effectiveness.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]579
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]580</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]581
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]582</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]583
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]584
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]585<!--=========================================================================-->
586<div class="doc_subsection">
587<a name="executionengine">Interpreter and JIT Improvements</a>
588</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]589
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]590<div class="doc_text">
591
592<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]593<li>The JIT now supports generating debug information, which is compatible with
594the new GDB 7.0 (and later) interfaces for registering debug info for
595dynamically generated code.</li>
596
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]597<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin01eba392010-01-29 19:10:38 +0000[diff] [blame]598to compiling eagerly</a> to avoid a race condition in the lazy JIT.
599Clients that still want the lazy JIT can switch it on by calling
600<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]601
Jeffrey Yasskin40966a72010-02-11 01:07:39 +0000[diff] [blame]602<li>It is now possible to create more than one JIT instance in the same process.
603These JITs can generate machine code in parallel,
604although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
605still have to obey the other threading restrictions</a>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]606
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]607</ul>
608
609</div>
610
611<!--=========================================================================-->
612<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]613<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]614</div>
615
616<div class="doc_text">
617
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]618<p>We have put a significant amount of work into the code generator
619infrastructure, which allows us to implement more aggressive algorithms and make
620it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]621
622<ul>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]623<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
624 to emit many useful comments to .s files indicating information about spill
625 slots and loop nest structure. This should make it much easier to read and
626 understand assembly files. This is wired up in llvm-gcc and clang to
627 the <tt>-fverbose-asm</tt> option.</li>
628
629<li>New LSR with "full strength reduction" mode. FIXME: Description?</li>
630
631<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
632 is available and enabled by default. It catches redundancies exposed by
633 lowering.</li>
634<li>A new pre-register-allocation tail duplication pass is available and enabled
635 by default, it can substantially improve branch prediction quality in some
636 cases.</li>
637<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
638 is available and enabled by default. This pass can takes advantage
639 architecture features like x86-64 implicit zero extension behavior and
640 sub-registers.</li>
641<li>The code generator now supports a mode where it attempts to preserve the
642 order of instructions in the input code. This is important for source that
643 is hand scheduled and extremely sensitive to scheduling. It is compatible
644 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
645<li>The target-independent code generator now supports generating code with
646 arbitrary numbers of result values. Returning more values than was
647 previously supported is handled by returning through a hidden pointer. In
648 2.7, only the X86 and XCore targets have adopted support for this
649 though.</li>
650<li>The code generator now supports generating code that follows the
651 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
652 Convention</a> and ABI.</li>
653<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
654 selection</a>" phase of the code generator has been largely rewritten for
655 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
656 linked into the target to do the pattern matching, now it emits a much
657 smaller table which is read by the target-independent code. The primary
658 advantages of this approach is that the size and compile time of various
659 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
660 for example.</li>
661<li>Almost the entire code generator has switched to emitting code through the
662 MC interfaces instead of printing textually to the .s file. This led to a
663 number of cleanups and speedups. In 2.7, debug an exception handling
664 information does not go through MC yet.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]665</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]666</div>
667
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]668<!--=========================================================================-->
669<div class="doc_subsection">
670<a name="x86">X86-32 and X86-64 Target Improvements</a>
671</div>
672
673<div class="doc_text">
674<p>New features of the X86 target include:
675</p>
676
677<ul>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]678<li>The X86 backend now optimizes tails calls much more aggressively for
679 functions that use the standard C calling convention.</li>
680<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
681 registers, making the code generator more aggressive in cases where scalars
682 and vector types are mixed.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]683
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]684<li>PostRA scheduler for X86? FIXME: is this on by default in 2.7?</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]685
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]686</ul>
687
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]688</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]689
690<!--=========================================================================-->
691<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]692<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]693</div>
694
695<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]696<p>New features of the ARM target include:
697</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]698
699<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]700
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]701<li>The ARM backend now generates instructions in unified assembly syntax.</li>
702
703<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
704 support differs slightly from the GCC implementation. Please see the
705 <a
706href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
707 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
708 helpful information if migrating code from GCC to LLVM-GCC.</li>
709
710<li>The ARM and Thumb code generators now using register scavenging for stack
711 object address materialization.(FIXME: WHAT BENEFIT DOES THIS PROVIDE?)</li>
712
713<li>The ARM backend now has good support for ARMv4 targets, and has been tested
714 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
715 newer chips.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]716</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]717
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]718
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]719</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]720
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]721<!--=========================================================================-->
722<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]723<a name="newapis">New Useful APIs</a>
724</div>
725
726<div class="doc_text">
727
728<p>This release includes a number of new APIs that are used internally, which
729 may also be useful for external clients.
730</p>
731
732<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]733<li>The optimizer uses the new CodeMetrics class to measure the size of code.
734 Various passes that use thing (like the inliner, loop unswitcher, etc) all
735 use this to make more accurate estimates of the code size impact of various
736 optimizations.</li>
737<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
738 llvm/Analysis/InstructionSimplify.h</a> interface available for doing
739 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
740 without requiring the instruction to exist. This centralizes a lot of
741 ad-hoc symbolic manipulation code scattered in various passes.</li>
742<li>The optimizer now uses a new <a
743 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
744 class which efficiently supports
745 doing unstructured SSA update operations. This centralized a bunch of code
746 scattered through various passes (e.g. jump threading, lcssa, loop rotate,
747 etc) for doing this sort of thing. The code generator has an similar
748 <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
749 MachineSSAUpdater</a> class.</li>
750<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
751 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]752 expression API. Building on this, the <a
753 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
754 regular exressions.</li>
755<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
756 By default, this stream works the same way as "errs()", but if you pass
757 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
758 fixed sized circular buffer and the output is printed at the end of the
759 program's execution. This is helpful if you have a long lived compiler
760 process and you're interested in seeing snapshots in time.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]761</ul>
762
763
764</div>
765
766<!--=========================================================================-->
767<div class="doc_subsection">
768<a name="otherimprovements">Other Improvements and New Features</a>
769</div>
770
771<div class="doc_text">
772<p>Other miscellaneous features include:</p>
773
774<ul>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]775<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
776 get this, configure LLVM with the --enable-shared option.</li>
777
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]778<li>LLVM command line tools now overwrite their output by default, before they
779 would only do this with -f. This makes them more convenient to use, and
780 behave more like standard unix tools.</li>
781
782<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
783 file, and automatically do the right thing. This means you don't need to
784 explicitly use the llvm-as tool for most things.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]785</ul>
786
787</div>
788
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]789
790<!--=========================================================================-->
791<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]792<a name="changes">Major Changes and Removed Features</a>
793</div>
794
795<div class="doc_text">
796
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]797<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]798on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]799from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]800
801<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]802
803<li>
804The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
805("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
806profiling ("rsprofiling") passes have all been removed. They were not being
807actively maintained and had substantial problems. If you are interested in
808these components, you are welcome to ressurect them from SVN, fix the
809correctness problems, and resubmit them to mainline.</li>
810
811<li>LLVM now defaults to building most libraries with RTTI turned off, providing
812a code size reduction. Packagers who are interested in building LLVM to support
813plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
814and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
815document.</li>
816
Jeffrey Yasskinbc83d062010-02-09 23:03:44 +0000[diff] [blame]817<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
818if you have it installed. This makes it more likely that an LLVM built on one
819system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]820configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]821
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]822<li>Debug information uses a completely different representation, an LLVM 2.6
823.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
824
825<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
826 along with LowerAllocations pass. Now you should just use a call to the
827 malloc and free functions in libc. These calls are optimized as well as
828 the old instructions were.</li>
829</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]830
831<p>In addition, many APIs have changed in this release. Some of the major LLVM
832API changes are:</p>
833
834<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]835<li>Just about everything has been converted to use raw_ostream instead of
836 std::ostream.</li>
837<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
838 instead.</li>
839<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
840 instead.</li>
Jeffrey Yasskin4fcd6072010-01-28 01:41:20 +0000[diff] [blame]841<li><tt>ModuleProvider</tt> has been <a
842href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
843and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
844Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
845replace <tt>getBitcodeModuleProvider</tt> with
846<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
847functions that used to accept <tt>ModuleProvider</tt>. Clients who
848wrote their own <tt>ModuleProvider</tt>s will need to derive from
849<tt>GVMaterializer</tt> instead and use
850<tt>Module::setMaterializer</tt> to attach it to a
851<tt>Module</tt>.</li>
852
853<li><tt>GhostLinkage</tt> has given up the ghost.
854<tt>GlobalValue</tt>s that have not yet been read from their backing
855storage have the same linkage they will have after being read in.
856Clients must replace calls to
857<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
858<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar4acdede2010-02-10 04:09:52 +0000[diff] [blame]859
Daniel Dunbarca1c8162010-02-14 01:47:19 +0000[diff] [blame]860<li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
861to <tt>llvm/System/DataTypes.h</tt>.</li>
862
Duncan Sands411432d2010-02-17 17:20:17 +0000[diff] [blame]863<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
864<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
865<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
866<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]867</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]868
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]869</div>
870
871
872
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]873<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]874<div class="doc_section">
875 <a name="portability">Portability and Supported Platforms</a>
876</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]877<!-- *********************************************************************** -->
878
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]879<div class="doc_text">
880
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]881<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]882
883<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]884<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]885 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
886 systems).</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]887<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]888 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]889<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]890<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
891 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]892<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]893<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]894</ul>
895
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]896<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]897to the machine and operating system on which it is built. However, minor
898porting may be required to get LLVM to work on new platforms. We welcome your
899portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]900
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]901</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]902
903<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]904<div class="doc_section">
905 <a name="knownproblems">Known Problems</a>
906</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]907<!-- *********************************************************************** -->
908
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]909<div class="doc_text">
910
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]911<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]912listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]913href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]914there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]915
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]916<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]917<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
918using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]919See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]920However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
921for x86/x86-64 has been made available from the third party AuroraUX Project
922that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
923</ul>
924
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]925</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]926
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]927<!-- ======================================================================= -->
928<div class="doc_subsection">
929 <a name="experimental">Experimental features included with this release</a>
930</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]931
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]932<div class="doc_text">
933
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]934<p>The following components of this LLVM release are either untested, known to
935be broken or unreliable, or are in early development. These components should
936not be relied on, and bugs should not be filed against them, but they may be
937useful 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]938components, please contact us on the <a
939href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]940
941<ul>
Wesley Peck7c4a1212010-03-18 14:31:30 +0000[diff] [blame]942<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
943 backends are experimental.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]944<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]945 supported value for this option. The MachO writer is experimental, and
946 works much better in mainline SVN.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]947</ul>
948
949</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]950
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]951<!-- ======================================================================= -->
952<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]953 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]954</div>
955
956<div class="doc_text">
957
958<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]959 <li>The X86 backend does not yet support
960 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
961 floating point stack</a>. It supports the 'f' and 't' constraints, but not
962 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]963 <li>The X86 backend generates inefficient floating point code when configured
964 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]965 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]966 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]967 runtime currently due to lack of support for the 'u' inline assembly
968 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]969 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]970 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]971 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]972</ul>
973
974</div>
975
976<!-- ======================================================================= -->
977<div class="doc_subsection">
978 <a name="ppc-be">Known problems with the PowerPC back-end</a>
979</div>
980
981<div class="doc_text">
982
983<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]984<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]985compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]986</ul>
987
988</div>
989
990<!-- ======================================================================= -->
991<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]992 <a name="arm-be">Known problems with the ARM back-end</a>
993</div>
994
995<div class="doc_text">
996
997<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]998<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]999processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1000results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1001<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1002</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1003</ul>
1004
1005</div>
1006
1007<!-- ======================================================================= -->
1008<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1009 <a name="sparc-be">Known problems with the SPARC back-end</a>
1010</div>
1011
1012<div class="doc_text">
1013
1014<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1015<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]1016 support the 64-bit SPARC ABI (-m64).</li>
1017</ul>
1018
1019</div>
1020
1021<!-- ======================================================================= -->
1022<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1023 <a name="mips-be">Known problems with the MIPS back-end</a>
1024</div>
1025
1026<div class="doc_text">
1027
1028<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1029<li>64-bit MIPS targets are not supported yet.</li>
1030</ul>
1031
1032</div>
1033
1034<!-- ======================================================================= -->
1035<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1036 <a name="alpha-be">Known problems with the Alpha back-end</a>
1037</div>
1038
1039<div class="doc_text">
1040
1041<ul>
1042
1043<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1044appropriate nops inserted to ensure restartability.</li>
1045
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1046</ul>
1047</div>
1048
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1049<!-- ======================================================================= -->
1050<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1051 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1052</div>
1053
1054<div class="doc_text">
1055
1056<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1057<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1058 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1059<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1060 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1061 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1062<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1063<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1064</ul>
1065
1066</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1067
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1068
1069<!-- ======================================================================= -->
1070<div class="doc_subsection">
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]1071 <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]1072</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1073
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1074<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1075
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1076<p>The only major language feature of GCC not supported by llvm-gcc is
1077 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1078 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1079 supported on some targets (these are used when you take the address of a
1080 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1081
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1082</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1083
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1084<!-- ======================================================================= -->
1085<div class="doc_subsection">
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1086 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1087</div>
1088
1089<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1090<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1091<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1092 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1093 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1094</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1095</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1096
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1097<!-- ======================================================================= -->
1098<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1099 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1100</div>
1101
1102<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1103The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1104technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1105<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1106<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]1107to lack of trampoline support (pointers to nested functions) on other platforms.
1108However, 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]1109which does support trampolines.</li>
1110<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]1111This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1112exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1113Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1114<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1115and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1116(c380004 also fails with gcc-4.2 mainline).
1117If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1118causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1119<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1120<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1121<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]1122crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1123<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1124or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1125or use representation clauses that result in a field of a non-discrete type
1126starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1127<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1128'main' as generated by the Ada binder to be invalid</a>.
1129Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1130<tt>envp</tt> rather than integers.</li>
1131<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1132ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1133</ul>
1134</div>
1135
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1136<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1137<div class="doc_section">
1138 <a name="additionalinfo">Additional Information</a>
1139</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1140<!-- *********************************************************************** -->
1141
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1142<div class="doc_text">
1143
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1144<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1145href="http://llvm.org">LLVM web page</a>, in particular in the <a
1146href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1147contains versions of the API documentation which is up-to-date with the
1148Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1149You can access versions of these documents specific to this release by going
1150into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1151
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1152<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]1153us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1154lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1155
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1156</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1157
1158<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1159
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1160<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1161<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1162 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1163 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1164 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1165 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]1166
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1167 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1168 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1169</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1170
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1171</body>
1172</html>