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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / c8b3af9f5fea6ba9aa834009fd4e71ae5384f653 / . / 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
Daniel Dunbar60dadb62010-03-25 16:09:18 +0000[diff] [blame]125<li>CIndex API and Python bindings: Clang now includes a C API as part of the
126CIndex library. Although we make make some changes to the API in the future, it
127is intended to be stable and has been designed for use by external projects. See
128the Clang
129doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
130documentation for more details. The CIndex API also includings an preliminary
131set of Python bindings.</li>
132
133<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
134ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
135suitable for use as a a beta quality ARM compiler.</li>
Bill Wendling6bc15282009-03-02 04:28:18 +0000[diff] [blame]136</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]137</div>
138
139<!--=========================================================================-->
140<div class="doc_subsection">
141<a name="clangsa">Clang Static Analyzer</a>
142</div>
143
144<div class="doc_text">
145
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]146<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
147 project is an effort to use static source code analysis techniques to
148 automatically find bugs in C and Objective-C programs (and hopefully <a
149 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
150 future</a>!). The tool is very good at finding bugs that occur on specific
151 paths through code, such as on error conditions.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]152
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]153<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
154 minor improvements, including better support for tracking the fields of
155 structures, initial support (not enabled by default yet) for doing
156 interprocedural (cross-function) analysis, and new checks have been added.
157</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]158
159</div>
160
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]161<!--=========================================================================-->
162<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]163<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]164</div>
165
166<div class="doc_text">
167<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]168The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]169a JVM and a CLI Virtual Machine (Microsoft .NET is an
170implementation of the CLI) using LLVM for static and just-in-time
171compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]172
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]173<p>
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]174With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
175virtual machines. VMKit now offers precise and efficient garbage collection with
176multi-threading support, thanks to the MMTk memory management toolkit, as well
177as just in time and ahead of time compilation with LLVM. The major changes in
178VMKit 0.27 are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]179
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]180<ul>
181
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]182<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
183 The first collector to be ported is the MarkSweep collector, which is precise,
184 and drastically improves the performance of VMKit.</li>
185<li>Line number information in the JVM: by using the debug metadata of LLVM, the
186 JVM now supports precise line number information, useful when printing a stack
187 trace.</li>
188<li>Interface calls in the JVM: we implemented a variant of the Interface Method
189 Table technique for interface calls in the JVM.
190</li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]191
192</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]193</div>
194
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]195
196<!--=========================================================================-->
197<div class="doc_subsection">
198<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
199</div>
200
201<div class="doc_text">
202<p>
203The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
204is a simple library that provides an implementation of the low-level
205target-specific hooks required by code generation and other runtime components.
206For example, when compiling for a 32-bit target, converting a double to a 64-bit
207unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
208function. The compiler-rt library provides highly optimized implementations of
209this and other low-level routines (some are 3x faster than the equivalent
210libgcc routines).</p>
211
212<p>
213All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]214License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
215supports ARM targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]216
217</div>
218
219<!--=========================================================================-->
220<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]221<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]222</div>
223
224<div class="doc_text">
225<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]226<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
227gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
228gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
229whatsoever (currently one small patch is needed). This is thanks to the new
230<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
231makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
232which is nothing more than a dynamic library which conforms to the gcc plugin
233interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
234instead of the gcc optimizers, and the LLVM code generators instead of the gcc
235code generators, just like llvm-gcc. To use it, you add
236"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
237becomes llvm-gcc-4.5!
238</p>
239
240<p>
241DragonEgg is still a work in progress. Currently C works very well, while C++,
242Ada and Fortran work fairly well. All other languages either don't work at all,
243or 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]244supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]245</p>
246
247<p>
Duncan Sandscb9dda62010-04-21 13:51:48 +0000[diff] [blame]248DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]249</p>
250
251</div>
252
253
254<!--=========================================================================-->
255<div class="doc_subsection">
256<a name="mc">llvm-mc: Machine Code Toolkit</a>
257</div>
258
259<div class="doc_text">
260<p>
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]261The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
262of problems in the realm of assembly, disassembly, object file format handling,
263and a number of other related areas that CPU instruction-set level tools work
264in. It is a sub-project of LLVM which provides it with a number of advantages
265over other compilers that do not have tightly integrated assembly-level tools.
266For a gentle introduction, please see the <a
267href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
268LLVM MC Project Blog Post</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]269</p>
270
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]271<p>2.7 includes major parts of the work required by the new MC Project. A few
272 targets have been refactored to support it, and work is underway to support a
273 native assembler in LLVM. This work is not complete in LLVM 2.7, but you has
274 made substantially more progress on LLVM mainline.</p>
275
276<p>One minor example of what MC can do is to transcode an AT&amp;T syntax
277 X86 .s file into intel syntax. You can do this with something like:</p>
278
279<pre>
280 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
281</pre>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]282</p>
283
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]284</div>
285
286
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]287<!-- *********************************************************************** -->
288<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]289 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]290</div>
291<!-- *********************************************************************** -->
292
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]293<div class="doc_text">
294
295<p>An exciting aspect of LLVM is that it is used as an enabling technology for
296 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]297 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]298</div>
299
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]300<!--=========================================================================-->
301<div class="doc_subsection">
302<a name="pure">Pure</a>
303</div>
304
305<div class="doc_text">
306<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]307<a href="http://pure-lang.googlecode.com/">Pure</a>
308is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]309Programs are collections of equations which are used to evaluate expressions in
310a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]311lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]312built-in list and matrix support (including list and matrix comprehensions) and
313an easy-to-use C interface. The interpreter uses LLVM as a backend to
314 JIT-compile Pure programs to fast native code.</p>
315
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]316<p>Pure versions 0.43 and later have been tested and are known to work with
317LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
318
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]319</div>
320
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]321<!--=========================================================================-->
322<div class="doc_subsection">
323<a name="RoadsendPHP">Roadsend PHP</a>
324</div>
325
326<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]327<p>
328<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]329source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]330language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]331reimplementation of an earlier project that is now based on LLVM.
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]332</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]333</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]334
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]335<!--=========================================================================-->
336<div class="doc_subsection">
337<a name="UnladenSwallow">Unladen Swallow</a>
338</div>
339
340<div class="doc_text">
341<p>
342<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
343branch of <a href="http://python.org/">Python</a> intended to be fully
344compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerb5f6feb2010-03-18 06:52:15 +0000[diff] [blame]345compiler.
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]346</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]347</div>
348
349<!--=========================================================================-->
350<div class="doc_subsection">
Chris Lattner8d4bbbe2010-03-29 17:50:39 +0000[diff] [blame]351<a name="tce">TTA-based Codesign Environment (TCE)</a>
352</div>
353
354<div class="doc_text">
355<p>
356<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
357application-specific processors (ASP) based on the Transport triggered
358architecture (TTA). The toolset provides a complete co-design flow from C/C++
359programs down to synthesizable VHDL and parallel program binaries. Processor
360customization points include the register files, function units, supported
361operations, and the interconnection network.</p>
362
363<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
364independent optimizations and also for parts of code generation. It generates
365new LLVM-based code generators "on the fly" for the designed TTA processors and
366loads them in to the compiler backend as runtime libraries to avoid per-target
367recompilation of larger parts of the compiler chain.</p>
368
369</div>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]370
John Criswellf77cdab2010-04-06 14:52:14 +0000[diff] [blame]371<!--=========================================================================-->
372<div class="doc_subsection">
373<a name="safecode">SAFECode Compiler</a>
374</div>
375
376<div class="doc_text">
377<p>
378<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
379compiler built using LLVM. It takes standard, unannotated C code, analyzes the
380code to ensure that memory accesses and array indexing operations are safe, and
381instruments the code with run-time checks when safety cannot be proven
382statically.
383</p>
384</div>
385
386
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]387<!-- *********************************************************************** -->
388<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]389 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]390</div>
391<!-- *********************************************************************** -->
392
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]393<div class="doc_text">
394
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]395<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]396minor improvements. Some of the major improvements and new features are listed
397in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]398</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]399
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]400</div>
401
402<!--=========================================================================-->
403<div class="doc_subsection">
404<a name="orgchanges">LLVM Community Changes</a>
405</div>
406
407<div class="doc_text">
408
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]409<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
410organization changes have happened:
411</p>
412
413<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]414<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]415
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]416<li>Ted Kremenek and Doug Gregor have stepped forward as <a
417 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]418 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]419
420<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
421 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
422 to learn about new LLVM-related features as they are implemented. Several
423 features in this release are already explained on the blog.</li>
424
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]425<li>The LLVM web pages are now checked into the SVN server, in the "www",
426 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]427 largely inaccessible old CVS server.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]428
429<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
430 faster) server. It is still graciously hosted at the University of Illinois
431 of Urbana Champaign.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]432</ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]433</div>
434
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]435<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]436<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]437<a name="majorfeatures">Major New Features</a>
438</div>
439
440<div class="doc_text">
441
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]442<p>LLVM 2.7 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]443
444<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]445<li>2.7 includes initial support for the <a
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]446 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
447 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]448
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]449<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]450 supports many different use cases, including allowing front-end authors to
451 encode source level information into LLVM IR, which is consumed by later
452 language-specific passes. This is a great way to do high-level optimizations
453 like devirtualization, type-based alias analysis, etc. See the <a
454 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
455 Extensible Metadata Blog Post</a> for more information.</li>
456
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]457<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]458in a completely new way, built on extensible metadata. The new implementation
459is much more memory efficient and paves the way for improvements to optimized
460code debugging experience.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]461
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]462<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]463 indirect branch through a pointer. This is particularly useful for
464 interpreter loops, and is used to implement the GCC "address of label"
465 extension. For more information, see the <a
466href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
467Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]468
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]469<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]470 disassembling target machine code. These APIs are useful for a variety of
471 low level clients, and are surfaced in the new "enhanced disassembly" API.
472 For more information see the <a
473 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
474 Disassembler Blog Post</a> for more information.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]475
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]476<li>2.7 includes major parts of the work required by the new MC Project,
477 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]478</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]479
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]480</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]481
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]482</div>
483
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]484<!--=========================================================================-->
485<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]486<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]487</div>
488
489<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]490<p>LLVM IR has several new features for better support of new targets and that
491expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]492
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]493<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]494<li>LLVM IR now supports a 16-bit "half float" data type through <a
495 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
496<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]497 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]498 optimizer that a function was declared 'inline' and thus the inliner should
499 weight it higher when considering inlining it. The later
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]500 indicates to the code generator that the function diverges from the platform
501 ABI on stack alignment.</li>
502<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
503 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]504 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]505 extension.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]506<li>LLVM IR now supports marking load and store instructions with <a
507 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
508 metadata feature). This hint encourages the code
509 generator to generate non-temporal accesses when possible, which are useful
510 for code that is carefully managing cache behavior. Currently, only the
511 X86 backend provides target support for this feature.</li>
512
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]513<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifc8b3af92010-04-22 10:11:24 +0000[diff] [blame^]514 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]515 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]516 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]517</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]518</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]519
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]520</div>
521
522<!--=========================================================================-->
523<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]524<a name="optimizer">Optimizer Improvements</a>
525</div>
526
527<div class="doc_text">
528
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]529<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]530release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]531
532<ul>
533
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]534<li>The inliner reuses now merges arrays stack objects in different callees when
535 inlining multiple call sites into one function. This reduces the stack size
536 of the resultant function.</li>
537<li>The -basicaa alias analysis pass (which is the default) has been improved to
538 be less dependent on "type safe" pointers. It can now look through bitcasts
539 and other constructs more aggressively, allowing better load/store
540 optimization.</li>
541<li>The load elimination optimization in the GVN Pass [<a
542href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
543 blog post</a>] has been substantially improved to be more aggressive about
544 partial redundancy elimination and do more aggressive phi translation. Please
545 see the <a
546 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
547 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
548 Blog Post</a> for more details.</li>
549<li>The module <a href="LangRef.html#datalayout">target data string</a> now
550 includes a notion of what the 'native' integer data types a for the target,
551 which allows various optimizations to use. This helps mid-level
552 optimizations avoid promoting complex sequences of operations to data types
553 that are not natively supported (e.g. converting i32 operations to i64 on
554 a 32-bit chip).</li>
555<li>The mid-level optimizer is now conservative when operating on a module with
556 no target data. Previously, it would default to SparcV9 settings, which is
557 not what most people expected.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]558<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]559 conditionals and threading blocks with otherwise complex logic. It has
560 subsumed the old "Conditional Propagation" pass, and -condprop has been
561 removed from LLVM 2.7.</li>
562<li>The -instcombine pass has been refactored from being one huge file to being
563 a library of its own. Internally, it uses a customized IRBuilder to clean
564 it up and simplify it.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]565
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]566<li>The optimal edge profiling pass is reliable and much more complete than in
567 2.6. It can be used with the llvm-prof tool but isn't wired up to the
568 llvm-gcc and clang command line options yet.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]569
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]570<li>A new experimental alias analysis implementation, -scev-aa, has been added.
571 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
572 pointer offset expressions to disambiguate pointers. It can catch a few
573 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]574
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]575<li>The default pass ordering has been tweaked for improved optimization
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]576 effectiveness.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]577
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]578</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]579
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]580</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]581
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]582
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]583<!--=========================================================================-->
584<div class="doc_subsection">
585<a name="executionengine">Interpreter and JIT Improvements</a>
586</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]587
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]588<div class="doc_text">
589
590<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]591<li>The JIT now supports generating debug information, which is compatible with
592the new GDB 7.0 (and later) interfaces for registering debug info for
593dynamically generated code.</li>
594
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]595<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin01eba392010-01-29 19:10:38 +0000[diff] [blame]596to compiling eagerly</a> to avoid a race condition in the lazy JIT.
597Clients that still want the lazy JIT can switch it on by calling
598<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]599
Jeffrey Yasskin40966a72010-02-11 01:07:39 +0000[diff] [blame]600<li>It is now possible to create more than one JIT instance in the same process.
601These JITs can generate machine code in parallel,
602although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
603still have to obey the other threading restrictions</a>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]604
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]605</ul>
606
607</div>
608
609<!--=========================================================================-->
610<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]611<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]612</div>
613
614<div class="doc_text">
615
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]616<p>We have put a significant amount of work into the code generator
617infrastructure, which allows us to implement more aggressive algorithms and make
618it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]619
620<ul>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]621<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
622 to emit many useful comments to .s files indicating information about spill
623 slots and loop nest structure. This should make it much easier to read and
624 understand assembly files. This is wired up in llvm-gcc and clang to
625 the <tt>-fverbose-asm</tt> option.</li>
626
627<li>New LSR with "full strength reduction" mode. FIXME: Description?</li>
628
629<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
630 is available and enabled by default. It catches redundancies exposed by
631 lowering.</li>
632<li>A new pre-register-allocation tail duplication pass is available and enabled
633 by default, it can substantially improve branch prediction quality in some
634 cases.</li>
635<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
636 is available and enabled by default. This pass can takes advantage
637 architecture features like x86-64 implicit zero extension behavior and
638 sub-registers.</li>
639<li>The code generator now supports a mode where it attempts to preserve the
640 order of instructions in the input code. This is important for source that
641 is hand scheduled and extremely sensitive to scheduling. It is compatible
642 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
643<li>The target-independent code generator now supports generating code with
644 arbitrary numbers of result values. Returning more values than was
645 previously supported is handled by returning through a hidden pointer. In
646 2.7, only the X86 and XCore targets have adopted support for this
647 though.</li>
648<li>The code generator now supports generating code that follows the
649 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
650 Convention</a> and ABI.</li>
651<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
652 selection</a>" phase of the code generator has been largely rewritten for
653 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
654 linked into the target to do the pattern matching, now it emits a much
655 smaller table which is read by the target-independent code. The primary
656 advantages of this approach is that the size and compile time of various
657 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
658 for example.</li>
659<li>Almost the entire code generator has switched to emitting code through the
660 MC interfaces instead of printing textually to the .s file. This led to a
661 number of cleanups and speedups. In 2.7, debug an exception handling
662 information does not go through MC yet.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]663</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]664</div>
665
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]666<!--=========================================================================-->
667<div class="doc_subsection">
668<a name="x86">X86-32 and X86-64 Target Improvements</a>
669</div>
670
671<div class="doc_text">
672<p>New features of the X86 target include:
673</p>
674
675<ul>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]676<li>The X86 backend now optimizes tails calls much more aggressively for
677 functions that use the standard C calling convention.</li>
678<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
679 registers, making the code generator more aggressive in cases where scalars
680 and vector types are mixed.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]681
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]682<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]683
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]684</ul>
685
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]686</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]687
688<!--=========================================================================-->
689<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]690<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]691</div>
692
693<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]694<p>New features of the ARM target include:
695</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]696
697<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]698
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]699<li>The ARM backend now generates instructions in unified assembly syntax.</li>
700
701<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
702 support differs slightly from the GCC implementation. Please see the
703 <a
704href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
705 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
706 helpful information if migrating code from GCC to LLVM-GCC.</li>
707
708<li>The ARM and Thumb code generators now using register scavenging for stack
709 object address materialization.(FIXME: WHAT BENEFIT DOES THIS PROVIDE?)</li>
710
711<li>The ARM backend now has good support for ARMv4 targets, and has been tested
712 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
713 newer chips.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]714</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]715
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]716
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]717</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]718
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]719<!--=========================================================================-->
720<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]721<a name="newapis">New Useful APIs</a>
722</div>
723
724<div class="doc_text">
725
726<p>This release includes a number of new APIs that are used internally, which
727 may also be useful for external clients.
728</p>
729
730<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]731<li>The optimizer uses the new CodeMetrics class to measure the size of code.
732 Various passes that use thing (like the inliner, loop unswitcher, etc) all
733 use this to make more accurate estimates of the code size impact of various
734 optimizations.</li>
735<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
736 llvm/Analysis/InstructionSimplify.h</a> interface available for doing
737 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
738 without requiring the instruction to exist. This centralizes a lot of
739 ad-hoc symbolic manipulation code scattered in various passes.</li>
740<li>The optimizer now uses a new <a
741 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
742 class which efficiently supports
743 doing unstructured SSA update operations. This centralized a bunch of code
744 scattered through various passes (e.g. jump threading, lcssa, loop rotate,
745 etc) for doing this sort of thing. The code generator has an similar
746 <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
747 MachineSSAUpdater</a> class.</li>
748<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
749 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]750 expression API. Building on this, the <a
751 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
752 regular exressions.</li>
753<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
754 By default, this stream works the same way as "errs()", but if you pass
755 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
756 fixed sized circular buffer and the output is printed at the end of the
757 program's execution. This is helpful if you have a long lived compiler
758 process and you're interested in seeing snapshots in time.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]759</ul>
760
761
762</div>
763
764<!--=========================================================================-->
765<div class="doc_subsection">
766<a name="otherimprovements">Other Improvements and New Features</a>
767</div>
768
769<div class="doc_text">
770<p>Other miscellaneous features include:</p>
771
772<ul>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]773<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
774 get this, configure LLVM with the --enable-shared option.</li>
775
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]776<li>LLVM command line tools now overwrite their output by default, before they
777 would only do this with -f. This makes them more convenient to use, and
778 behave more like standard unix tools.</li>
779
780<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
781 file, and automatically do the right thing. This means you don't need to
782 explicitly use the llvm-as tool for most things.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]783</ul>
784
785</div>
786
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]787
788<!--=========================================================================-->
789<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]790<a name="changes">Major Changes and Removed Features</a>
791</div>
792
793<div class="doc_text">
794
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]795<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]796on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]797from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]798
799<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]800
801<li>
802The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
803("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
804profiling ("rsprofiling") passes have all been removed. They were not being
805actively maintained and had substantial problems. If you are interested in
806these components, you are welcome to ressurect them from SVN, fix the
807correctness problems, and resubmit them to mainline.</li>
808
809<li>LLVM now defaults to building most libraries with RTTI turned off, providing
810a code size reduction. Packagers who are interested in building LLVM to support
811plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
812and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
813document.</li>
814
Jeffrey Yasskinbc83d062010-02-09 23:03:44 +0000[diff] [blame]815<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
816if you have it installed. This makes it more likely that an LLVM built on one
817system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]818configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]819
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]820<li>Debug information uses a completely different representation, an LLVM 2.6
821.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
822
823<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
824 along with LowerAllocations pass. Now you should just use a call to the
825 malloc and free functions in libc. These calls are optimized as well as
826 the old instructions were.</li>
827</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]828
829<p>In addition, many APIs have changed in this release. Some of the major LLVM
830API changes are:</p>
831
832<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]833<li>Just about everything has been converted to use raw_ostream instead of
834 std::ostream.</li>
835<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
836 instead.</li>
837<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
838 instead.</li>
Jeffrey Yasskin4fcd6072010-01-28 01:41:20 +0000[diff] [blame]839<li><tt>ModuleProvider</tt> has been <a
840href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
841and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
842Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
843replace <tt>getBitcodeModuleProvider</tt> with
844<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
845functions that used to accept <tt>ModuleProvider</tt>. Clients who
846wrote their own <tt>ModuleProvider</tt>s will need to derive from
847<tt>GVMaterializer</tt> instead and use
848<tt>Module::setMaterializer</tt> to attach it to a
849<tt>Module</tt>.</li>
850
851<li><tt>GhostLinkage</tt> has given up the ghost.
852<tt>GlobalValue</tt>s that have not yet been read from their backing
853storage have the same linkage they will have after being read in.
854Clients must replace calls to
855<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
856<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar4acdede2010-02-10 04:09:52 +0000[diff] [blame]857
Daniel Dunbarca1c8162010-02-14 01:47:19 +0000[diff] [blame]858<li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
859to <tt>llvm/System/DataTypes.h</tt>.</li>
860
Duncan Sands411432d2010-02-17 17:20:17 +0000[diff] [blame]861<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
862<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
863<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
864<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]865</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]866
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]867</div>
868
869
870
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]871<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]872<div class="doc_section">
873 <a name="portability">Portability and Supported Platforms</a>
874</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]875<!-- *********************************************************************** -->
876
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]877<div class="doc_text">
878
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]879<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]880
881<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]882<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]883 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
884 systems).</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]885<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]886 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]887<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]888<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
889 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]890<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]891<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]892</ul>
893
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]894<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]895to the machine and operating system on which it is built. However, minor
896porting may be required to get LLVM to work on new platforms. We welcome your
897portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]898
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]899</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]900
901<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]902<div class="doc_section">
903 <a name="knownproblems">Known Problems</a>
904</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]905<!-- *********************************************************************** -->
906
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]907<div class="doc_text">
908
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]909<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]910listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]911href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]912there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]913
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]914<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]915<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
916using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]917See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]918However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
919for x86/x86-64 has been made available from the third party AuroraUX Project
920that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
921</ul>
922
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]923</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]924
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]925<!-- ======================================================================= -->
926<div class="doc_subsection">
927 <a name="experimental">Experimental features included with this release</a>
928</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]929
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]930<div class="doc_text">
931
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]932<p>The following components of this LLVM release are either untested, known to
933be broken or unreliable, or are in early development. These components should
934not be relied on, and bugs should not be filed against them, but they may be
935useful 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]936components, please contact us on the <a
937href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]938
939<ul>
Wesley Peck7c4a1212010-03-18 14:31:30 +0000[diff] [blame]940<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
941 backends are experimental.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]942<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]943 supported value for this option. The MachO writer is experimental, and
944 works much better in mainline SVN.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]945</ul>
946
947</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]948
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]949<!-- ======================================================================= -->
950<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]951 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]952</div>
953
954<div class="doc_text">
955
956<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]957 <li>The X86 backend does not yet support
958 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
959 floating point stack</a>. It supports the 'f' and 't' constraints, but not
960 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]961 <li>The X86 backend generates inefficient floating point code when configured
962 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]963 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]964 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]965 runtime currently due to lack of support for the 'u' inline assembly
966 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]967 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]968 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]969 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]970</ul>
971
972</div>
973
974<!-- ======================================================================= -->
975<div class="doc_subsection">
976 <a name="ppc-be">Known problems with the PowerPC back-end</a>
977</div>
978
979<div class="doc_text">
980
981<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]982<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]983compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]984</ul>
985
986</div>
987
988<!-- ======================================================================= -->
989<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]990 <a name="arm-be">Known problems with the ARM back-end</a>
991</div>
992
993<div class="doc_text">
994
995<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]996<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]997processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]998results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]999<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1000</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1001</ul>
1002
1003</div>
1004
1005<!-- ======================================================================= -->
1006<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1007 <a name="sparc-be">Known problems with the SPARC back-end</a>
1008</div>
1009
1010<div class="doc_text">
1011
1012<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1013<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]1014 support the 64-bit SPARC ABI (-m64).</li>
1015</ul>
1016
1017</div>
1018
1019<!-- ======================================================================= -->
1020<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1021 <a name="mips-be">Known problems with the MIPS back-end</a>
1022</div>
1023
1024<div class="doc_text">
1025
1026<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1027<li>64-bit MIPS targets are not supported yet.</li>
1028</ul>
1029
1030</div>
1031
1032<!-- ======================================================================= -->
1033<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1034 <a name="alpha-be">Known problems with the Alpha back-end</a>
1035</div>
1036
1037<div class="doc_text">
1038
1039<ul>
1040
1041<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1042appropriate nops inserted to ensure restartability.</li>
1043
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1044</ul>
1045</div>
1046
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1047<!-- ======================================================================= -->
1048<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1049 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1050</div>
1051
1052<div class="doc_text">
1053
1054<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1055<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1056 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1057<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1058 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1059 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1060<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1061<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1062</ul>
1063
1064</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1065
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1066
1067<!-- ======================================================================= -->
1068<div class="doc_subsection">
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]1069 <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]1070</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1071
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1072<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1073
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1074<p>The only major language feature of GCC not supported by llvm-gcc is
1075 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1076 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1077 supported on some targets (these are used when you take the address of a
1078 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1079
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1080</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1081
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1082<!-- ======================================================================= -->
1083<div class="doc_subsection">
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1084 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1085</div>
1086
1087<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1088<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1089<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1090 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1091 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1092</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1093</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1094
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1095<!-- ======================================================================= -->
1096<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1097 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1098</div>
1099
1100<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1101The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1102technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1103<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1104<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]1105to lack of trampoline support (pointers to nested functions) on other platforms.
1106However, 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]1107which does support trampolines.</li>
1108<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]1109This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1110exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1111Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1112<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1113and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1114(c380004 also fails with gcc-4.2 mainline).
1115If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1116causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1117<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1118<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1119<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]1120crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1121<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1122or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1123or use representation clauses that result in a field of a non-discrete type
1124starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1125<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1126'main' as generated by the Ada binder to be invalid</a>.
1127Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1128<tt>envp</tt> rather than integers.</li>
1129<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1130ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1131</ul>
1132</div>
1133
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1134<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1135<div class="doc_section">
1136 <a name="additionalinfo">Additional Information</a>
1137</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1138<!-- *********************************************************************** -->
1139
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1140<div class="doc_text">
1141
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1142<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1143href="http://llvm.org">LLVM web page</a>, in particular in the <a
1144href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1145contains versions of the API documentation which is up-to-date with the
1146Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1147You can access versions of these documents specific to this release by going
1148into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1149
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1150<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]1151us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1152lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1153
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1154</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1155
1156<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1157
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1158<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1159<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1160 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1161 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1162 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1163 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]1164
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1165 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1166 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1167</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1168
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1169</body>
1170</html>