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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 914ce46040f7469c6ca40fb8de9217f8d4813f03 / . / 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"
2 "http://www.w3.org/TR/html4/strict.dtd">
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
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]148<p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]149includes an early stage static source code analysis tool for <a
150href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]151in C and Objective-C programs. The tool performs checks to find
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]152bugs that occur on a specific path within a program.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]153
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]154<p>In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]155
156</div>
157
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]158<!--=========================================================================-->
159<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]160<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]161</div>
162
163<div class="doc_text">
164<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]165The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]166a JVM and a CLI Virtual Machine (Microsoft .NET is an
167implementation of the CLI) using LLVM for static and just-in-time
168compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]169
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]170<p>
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]171With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
172virtual machines. VMKit now offers precise and efficient garbage collection with
173multi-threading support, thanks to the MMTk memory management toolkit, as well
174as just in time and ahead of time compilation with LLVM. The major changes in
175VMKit 0.27 are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]176
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]177<ul>
178
Chris Lattnerbf8e5162010-03-29 18:34:13 +0000[diff] [blame]179<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
180 The first collector to be ported is the MarkSweep collector, which is precise,
181 and drastically improves the performance of VMKit.</li>
182<li>Line number information in the JVM: by using the debug metadata of LLVM, the
183 JVM now supports precise line number information, useful when printing a stack
184 trace.</li>
185<li>Interface calls in the JVM: we implemented a variant of the Interface Method
186 Table technique for interface calls in the JVM.
187</li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]188
189</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]190</div>
191
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]192
193<!--=========================================================================-->
194<div class="doc_subsection">
195<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
196</div>
197
198<div class="doc_text">
199<p>
200The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
201is a simple library that provides an implementation of the low-level
202target-specific hooks required by code generation and other runtime components.
203For example, when compiling for a 32-bit target, converting a double to a 64-bit
204unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
205function. The compiler-rt library provides highly optimized implementations of
206this and other low-level routines (some are 3x faster than the equivalent
207libgcc routines).</p>
208
209<p>
210All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]211License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
212supports ARM targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]213
214</div>
215
216<!--=========================================================================-->
217<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]218<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]219</div>
220
221<div class="doc_text">
222<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]223<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
224gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
225gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
226whatsoever (currently one small patch is needed). This is thanks to the new
227<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
228makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
229which is nothing more than a dynamic library which conforms to the gcc plugin
230interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
231instead of the gcc optimizers, and the LLVM code generators instead of the gcc
232code generators, just like llvm-gcc. To use it, you add
233"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
234becomes llvm-gcc-4.5!
235</p>
236
237<p>
238DragonEgg is still a work in progress. Currently C works very well, while C++,
239Ada and Fortran work fairly well. All other languages either don't work at all,
240or 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]241supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]242</p>
243
244<p>
Duncan Sandscb9dda62010-04-21 13:51:48 +0000[diff] [blame]245DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]246</p>
247
248</div>
249
250
251<!--=========================================================================-->
252<div class="doc_subsection">
253<a name="mc">llvm-mc: Machine Code Toolkit</a>
254</div>
255
256<div class="doc_text">
257<p>
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]258The LLVM Machine Code (MC) Toolkit project is ...
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]259</p>
260
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]261<p>
262MC Disassembler (with blog post), MCInstPrinter. Many X86 backend and AsmPrinter simplifications
263Can transcode from GAS to intel syntax with "llvm-mc foo.s -output-asm-variant=1"
264</p>
265
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]266</div>
267
268
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]269<!-- *********************************************************************** -->
270<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]271 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]272</div>
273<!-- *********************************************************************** -->
274
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]275<div class="doc_text">
276
277<p>An exciting aspect of LLVM is that it is used as an enabling technology for
278 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]279 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]280</div>
281
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]282<!--=========================================================================-->
283<div class="doc_subsection">
284<a name="pure">Pure</a>
285</div>
286
287<div class="doc_text">
288<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]289<a href="http://pure-lang.googlecode.com/">Pure</a>
290is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]291Programs are collections of equations which are used to evaluate expressions in
292a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]293lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]294built-in list and matrix support (including list and matrix comprehensions) and
295an easy-to-use C interface. The interpreter uses LLVM as a backend to
296 JIT-compile Pure programs to fast native code.</p>
297
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]298<p>Pure versions 0.43 and later have been tested and are known to work with
299LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
300
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]301</div>
302
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]303<!--=========================================================================-->
304<div class="doc_subsection">
305<a name="RoadsendPHP">Roadsend PHP</a>
306</div>
307
308<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]309<p>
310<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]311source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]312language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]313reimplementation of an earlier project that is now based on LLVM.
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]314</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]315</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]316
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]317<!--=========================================================================-->
318<div class="doc_subsection">
319<a name="UnladenSwallow">Unladen Swallow</a>
320</div>
321
322<div class="doc_text">
323<p>
324<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
325branch of <a href="http://python.org/">Python</a> intended to be fully
326compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerb5f6feb2010-03-18 06:52:15 +0000[diff] [blame]327compiler.
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]328</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]329</div>
330
331<!--=========================================================================-->
332<div class="doc_subsection">
Chris Lattner8d4bbbe2010-03-29 17:50:39 +0000[diff] [blame]333<a name="tce">TTA-based Codesign Environment (TCE)</a>
334</div>
335
336<div class="doc_text">
337<p>
338<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
339application-specific processors (ASP) based on the Transport triggered
340architecture (TTA). The toolset provides a complete co-design flow from C/C++
341programs down to synthesizable VHDL and parallel program binaries. Processor
342customization points include the register files, function units, supported
343operations, and the interconnection network.</p>
344
345<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
346independent optimizations and also for parts of code generation. It generates
347new LLVM-based code generators "on the fly" for the designed TTA processors and
348loads them in to the compiler backend as runtime libraries to avoid per-target
349recompilation of larger parts of the compiler chain.</p>
350
351</div>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]352
John Criswellf77cdab2010-04-06 14:52:14 +0000[diff] [blame]353<!--=========================================================================-->
354<div class="doc_subsection">
355<a name="safecode">SAFECode Compiler</a>
356</div>
357
358<div class="doc_text">
359<p>
360<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
361compiler built using LLVM. It takes standard, unannotated C code, analyzes the
362code to ensure that memory accesses and array indexing operations are safe, and
363instruments the code with run-time checks when safety cannot be proven
364statically.
365</p>
366</div>
367
368
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]369<!-- *********************************************************************** -->
370<div class="doc_section">
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]371 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]372</div>
373<!-- *********************************************************************** -->
374
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]375<div class="doc_text">
376
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]377<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]378minor improvements. Some of the major improvements and new features are listed
379in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]380</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]381
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]382</div>
383
384<!--=========================================================================-->
385<div class="doc_subsection">
386<a name="orgchanges">LLVM Community Changes</a>
387</div>
388
389<div class="doc_text">
390
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]391<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
392organization changes have happened:
393</p>
394
395<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]396<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]397
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]398<li>Ted Kremenek and Doug Gregor have stepped forward as <a
399 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]400 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]401
402<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
403 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
404 to learn about new LLVM-related features as they are implemented. Several
405 features in this release are already explained on the blog.</li>
406
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]407<li>The LLVM web pages are now checked into the SVN server, in the "www",
408 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]409 largely inaccessible old CVS server.</li>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]410
411<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
412 faster) server. It is still graciously hosted at the University of Illinois
413 of Urbana Champaign.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]414</ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]415</div>
416
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]417<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]418<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]419<a name="majorfeatures">Major New Features</a>
420</div>
421
422<div class="doc_text">
423
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]424<p>LLVM 2.7 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]425
426<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]427<li>2.7 includes initial support for the <a
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]428 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
429 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]430
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]431<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]432 supports many different use cases, including allowing front-end authors to
433 encode source level information into LLVM IR, which is consumed by later
434 language-specific passes. This is a great way to do high-level optimizations
435 like devirtualization, type-based alias analysis, etc. See the <a
436 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
437 Extensible Metadata Blog Post</a> for more information.</li>
438
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]439<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]440in a completely new way, built on extensible metadata. The new implementation
441is much more memory efficient and paves the way for improvements to optimized
442code debugging experience.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]443
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]444<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]445 indirect branch through a pointer. This is particularly useful for
446 interpreter loops, and is used to implement the GCC "address of label"
447 extension. For more information, see the <a
448href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
449Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
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 is the first release to start supporting APIs for assembling and
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]452 disassembling target machine code. These APIs are useful for a variety of
453 low level clients, and are surfaced in the new "enhanced disassembly" API.
454 For more information see the <a
455 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
456 Disassembler Blog Post</a> for more information.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]457
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]458<li>2.7 includes major parts of the work required by the new MC Project,
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]459 which aims to rework our handling of low-level machine code. A few targets
460 have been refactored to support it, and work is underway to support a native
461 assembler in LLVM. This work is not complete in LLVM 2.7, but you has made
462 substantially more progress on LLVM mainline. You can read more about this
463 in the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">
464 Intro to the LLVM MC Project Blog Post</a>.
465</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]466
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]467</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]468
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]469</div>
470
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]471<!--=========================================================================-->
472<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]473<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]474</div>
475
476<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]477<p>LLVM IR has several new features for better support of new targets and that
478expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]479
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]480<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]481<li>LLVM IR now supports a 16-bit "half float" data type through <a
482 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
483<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]484 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]485 optimizer that a function was declared 'inline' and thus the inliner should
486 weight it higher when considering inlining it. The later
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]487 indicates to the code generator that the function diverges from the platform
488 ABI on stack alignment.</li>
489<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
490 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]491 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]492 extension.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]493<li>LLVM IR now supports marking load and store instructions with <a
494 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
495 metadata feature). This hint encourages the code
496 generator to generate non-temporal accesses when possible, which are useful
497 for code that is carefully managing cache behavior. Currently, only the
498 X86 backend provides target support for this feature.</li>
499
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]500<li>LLVM 2.7 has pre-alpha support for <a
501 href="http://llvm.org/docs/LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]502 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]503 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]504</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]505</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]506
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]507</div>
508
509<!--=========================================================================-->
510<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]511<a name="optimizer">Optimizer Improvements</a>
512</div>
513
514<div class="doc_text">
515
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]516<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]517release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]518
519<ul>
520
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]521<li>The inliner reuses now merges arrays stack objects in different callees when
522 inlining multiple call sites into one function. This reduces the stack size
523 of the resultant function.</li>
524<li>The -basicaa alias analysis pass (which is the default) has been improved to
525 be less dependent on "type safe" pointers. It can now look through bitcasts
526 and other constructs more aggressively, allowing better load/store
527 optimization.</li>
528<li>The load elimination optimization in the GVN Pass [<a
529href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
530 blog post</a>] has been substantially improved to be more aggressive about
531 partial redundancy elimination and do more aggressive phi translation. Please
532 see the <a
533 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
534 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
535 Blog Post</a> for more details.</li>
536<li>The module <a href="LangRef.html#datalayout">target data string</a> now
537 includes a notion of what the 'native' integer data types a for the target,
538 which allows various optimizations to use. This helps mid-level
539 optimizations avoid promoting complex sequences of operations to data types
540 that are not natively supported (e.g. converting i32 operations to i64 on
541 a 32-bit chip).</li>
542<li>The mid-level optimizer is now conservative when operating on a module with
543 no target data. Previously, it would default to SparcV9 settings, which is
544 not what most people expected.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]545<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]546 conditionals and threading blocks with otherwise complex logic. It has
547 subsumed the old "Conditional Propagation" pass, and -condprop has been
548 removed from LLVM 2.7.</li>
549<li>The -instcombine pass has been refactored from being one huge file to being
550 a library of its own. Internally, it uses a customized IRBuilder to clean
551 it up and simplify it.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]552
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]553<li>The optimal edge profiling pass is reliable and much more complete than in
554 2.6. It can be used with the llvm-prof tool but isn't wired up to the
555 llvm-gcc and clang command line options yet.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]556
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]557<li>A new experimental alias analysis implementation, -scev-aa, has been added.
558 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
559 pointer offset expressions to disambiguate pointers. It can catch a few
560 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]561
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]562<li>The default pass ordering has been tweaked for improved optimization
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]563 effectiveness.</li>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]564
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]565</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]566
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]567</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]568
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]569
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]570<!--=========================================================================-->
571<div class="doc_subsection">
572<a name="executionengine">Interpreter and JIT Improvements</a>
573</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]574
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]575<div class="doc_text">
576
577<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]578<li>The JIT now supports generating debug information, which is compatible with
579the new GDB 7.0 (and later) interfaces for registering debug info for
580dynamically generated code.</li>
581
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]582<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin01eba392010-01-29 19:10:38 +0000[diff] [blame]583to compiling eagerly</a> to avoid a race condition in the lazy JIT.
584Clients that still want the lazy JIT can switch it on by calling
585<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]586
Jeffrey Yasskin40966a72010-02-11 01:07:39 +0000[diff] [blame]587<li>It is now possible to create more than one JIT instance in the same process.
588These JITs can generate machine code in parallel,
589although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
590still have to obey the other threading restrictions</a>.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]591
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]592</ul>
593
594</div>
595
596<!--=========================================================================-->
597<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]598<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]599</div>
600
601<div class="doc_text">
602
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]603<p>We have put a significant amount of work into the code generator
604infrastructure, which allows us to implement more aggressive algorithms and make
605it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]606
607<ul>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]608<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
609 to emit many useful comments to .s files indicating information about spill
610 slots and loop nest structure. This should make it much easier to read and
611 understand assembly files. This is wired up in llvm-gcc and clang to
612 the <tt>-fverbose-asm</tt> option.</li>
613
614<li>New LSR with "full strength reduction" mode. FIXME: Description?</li>
615
616<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
617 is available and enabled by default. It catches redundancies exposed by
618 lowering.</li>
619<li>A new pre-register-allocation tail duplication pass is available and enabled
620 by default, it can substantially improve branch prediction quality in some
621 cases.</li>
622<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
623 is available and enabled by default. This pass can takes advantage
624 architecture features like x86-64 implicit zero extension behavior and
625 sub-registers.</li>
626<li>The code generator now supports a mode where it attempts to preserve the
627 order of instructions in the input code. This is important for source that
628 is hand scheduled and extremely sensitive to scheduling. It is compatible
629 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
630<li>The target-independent code generator now supports generating code with
631 arbitrary numbers of result values. Returning more values than was
632 previously supported is handled by returning through a hidden pointer. In
633 2.7, only the X86 and XCore targets have adopted support for this
634 though.</li>
635<li>The code generator now supports generating code that follows the
636 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
637 Convention</a> and ABI.</li>
638<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
639 selection</a>" phase of the code generator has been largely rewritten for
640 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
641 linked into the target to do the pattern matching, now it emits a much
642 smaller table which is read by the target-independent code. The primary
643 advantages of this approach is that the size and compile time of various
644 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
645 for example.</li>
646<li>Almost the entire code generator has switched to emitting code through the
647 MC interfaces instead of printing textually to the .s file. This led to a
648 number of cleanups and speedups. In 2.7, debug an exception handling
649 information does not go through MC yet.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]650</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]651</div>
652
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]653<!--=========================================================================-->
654<div class="doc_subsection">
655<a name="x86">X86-32 and X86-64 Target Improvements</a>
656</div>
657
658<div class="doc_text">
659<p>New features of the X86 target include:
660</p>
661
662<ul>
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]663<li>The X86 backend now optimizes tails calls much more aggressively for
664 functions that use the standard C calling convention.</li>
665<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
666 registers, making the code generator more aggressive in cases where scalars
667 and vector types are mixed.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]668
Chris Lattnera54c1f72010-04-21 06:42:24 +0000[diff] [blame]669<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]670
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]671</ul>
672
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]673</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]674
675<!--=========================================================================-->
676<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]677<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]678</div>
679
680<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]681<p>New features of the ARM target include:
682</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]683
684<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]685
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]686<li>The ARM backend now generates instructions in unified assembly syntax.</li>
687
688<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
689 support differs slightly from the GCC implementation. Please see the
690 <a
691href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
692 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
693 helpful information if migrating code from GCC to LLVM-GCC.</li>
694
695<li>The ARM and Thumb code generators now using register scavenging for stack
696 object address materialization.(FIXME: WHAT BENEFIT DOES THIS PROVIDE?)</li>
697
698<li>The ARM backend now has good support for ARMv4 targets, and has been tested
699 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
700 newer chips.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]701</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]702
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]703
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]704</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]705
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]706<!--=========================================================================-->
707<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]708<a name="newapis">New Useful APIs</a>
709</div>
710
711<div class="doc_text">
712
713<p>This release includes a number of new APIs that are used internally, which
714 may also be useful for external clients.
715</p>
716
717<ul>
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]718<li>The optimizer uses the new CodeMetrics class to measure the size of code.
719 Various passes that use thing (like the inliner, loop unswitcher, etc) all
720 use this to make more accurate estimates of the code size impact of various
721 optimizations.</li>
722<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
723 llvm/Analysis/InstructionSimplify.h</a> interface available for doing
724 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
725 without requiring the instruction to exist. This centralizes a lot of
726 ad-hoc symbolic manipulation code scattered in various passes.</li>
727<li>The optimizer now uses a new <a
728 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
729 class which efficiently supports
730 doing unstructured SSA update operations. This centralized a bunch of code
731 scattered through various passes (e.g. jump threading, lcssa, loop rotate,
732 etc) for doing this sort of thing. The code generator has an similar
733 <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
734 MachineSSAUpdater</a> class.</li>
735<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
736 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]737 expression API. Building on this, the <a
738 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
739 regular exressions.</li>
740<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
741 By default, this stream works the same way as "errs()", but if you pass
742 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
743 fixed sized circular buffer and the output is printed at the end of the
744 program's execution. This is helpful if you have a long lived compiler
745 process and you're interested in seeing snapshots in time.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]746</ul>
747
748
749</div>
750
751<!--=========================================================================-->
752<div class="doc_subsection">
753<a name="otherimprovements">Other Improvements and New Features</a>
754</div>
755
756<div class="doc_text">
757<p>Other miscellaneous features include:</p>
758
759<ul>
Chris Lattner450a31e2010-04-21 06:23:40 +0000[diff] [blame]760<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
761 get this, configure LLVM with the --enable-shared option.</li>
762
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]763<li>LLVM command line tools now overwrite their output by default, before they
764 would only do this with -f. This makes them more convenient to use, and
765 behave more like standard unix tools.</li>
766
767<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
768 file, and automatically do the right thing. This means you don't need to
769 explicitly use the llvm-as tool for most things.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]770</ul>
771
772</div>
773
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]774
775<!--=========================================================================-->
776<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]777<a name="changes">Major Changes and Removed Features</a>
778</div>
779
780<div class="doc_text">
781
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]782<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]783on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]784from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]785
786<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]787
788<li>
789The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
790("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
791profiling ("rsprofiling") passes have all been removed. They were not being
792actively maintained and had substantial problems. If you are interested in
793these components, you are welcome to ressurect them from SVN, fix the
794correctness problems, and resubmit them to mainline.</li>
795
796<li>LLVM now defaults to building most libraries with RTTI turned off, providing
797a code size reduction. Packagers who are interested in building LLVM to support
798plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
799and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
800document.</li>
801
Jeffrey Yasskinbc83d062010-02-09 23:03:44 +0000[diff] [blame]802<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
803if you have it installed. This makes it more likely that an LLVM built on one
804system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]805configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]806
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]807<li>Debug information uses a completely different representation, an LLVM 2.6
808.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
809
810<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
811 along with LowerAllocations pass. Now you should just use a call to the
812 malloc and free functions in libc. These calls are optimized as well as
813 the old instructions were.</li>
814</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]815
816<p>In addition, many APIs have changed in this release. Some of the major LLVM
817API changes are:</p>
818
819<ul>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]820<li>Just about everything has been converted to use raw_ostream instead of
821 std::ostream.</li>
822<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
823 instead.</li>
824<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
825 instead.</li>
Jeffrey Yasskin4fcd6072010-01-28 01:41:20 +0000[diff] [blame]826<li><tt>ModuleProvider</tt> has been <a
827href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
828and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
829Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
830replace <tt>getBitcodeModuleProvider</tt> with
831<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
832functions that used to accept <tt>ModuleProvider</tt>. Clients who
833wrote their own <tt>ModuleProvider</tt>s will need to derive from
834<tt>GVMaterializer</tt> instead and use
835<tt>Module::setMaterializer</tt> to attach it to a
836<tt>Module</tt>.</li>
837
838<li><tt>GhostLinkage</tt> has given up the ghost.
839<tt>GlobalValue</tt>s that have not yet been read from their backing
840storage have the same linkage they will have after being read in.
841Clients must replace calls to
842<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
843<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar4acdede2010-02-10 04:09:52 +0000[diff] [blame]844
Daniel Dunbarca1c8162010-02-14 01:47:19 +0000[diff] [blame]845<li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
846to <tt>llvm/System/DataTypes.h</tt>.</li>
847
Duncan Sands411432d2010-02-17 17:20:17 +0000[diff] [blame]848<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
849<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
850<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
851<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]852</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]853
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]854</div>
855
856
857
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]858<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]859<div class="doc_section">
860 <a name="portability">Portability and Supported Platforms</a>
861</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]862<!-- *********************************************************************** -->
863
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]864<div class="doc_text">
865
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]866<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]867
868<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]869<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]870 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
871 systems).</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]872<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]873 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]874<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]875<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
876 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]877<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]878<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]879</ul>
880
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]881<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]882to the machine and operating system on which it is built. However, minor
883porting may be required to get LLVM to work on new platforms. We welcome your
884portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]885
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]886</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]887
888<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]889<div class="doc_section">
890 <a name="knownproblems">Known Problems</a>
891</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]892<!-- *********************************************************************** -->
893
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]894<div class="doc_text">
895
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]896<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]897listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]898href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]899there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]900
Chris Lattner477a1fd2010-03-17 17:25:49 +0000[diff] [blame]901<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]902<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
903using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]904See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]905However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
906for x86/x86-64 has been made available from the third party AuroraUX Project
907that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
908</ul>
909
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]910</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]911
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]912<!-- ======================================================================= -->
913<div class="doc_subsection">
914 <a name="experimental">Experimental features included with this release</a>
915</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]916
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]917<div class="doc_text">
918
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]919<p>The following components of this LLVM release are either untested, known to
920be broken or unreliable, or are in early development. These components should
921not be relied on, and bugs should not be filed against them, but they may be
922useful 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]923components, please contact us on the <a
924href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]925
926<ul>
Wesley Peck7c4a1212010-03-18 14:31:30 +0000[diff] [blame]927<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
928 backends are experimental.</li>
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]929<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]930 supported value for this option. The MachO writer is experimental, and
931 works much better in mainline SVN.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]932</ul>
933
934</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]935
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]936<!-- ======================================================================= -->
937<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]938 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]939</div>
940
941<div class="doc_text">
942
943<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]944 <li>The X86 backend does not yet support
945 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
946 floating point stack</a>. It supports the 'f' and 't' constraints, but not
947 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]948 <li>The X86 backend generates inefficient floating point code when configured
949 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]950 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]951 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]952 runtime currently due to lack of support for the 'u' inline assembly
953 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]954 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame^]955 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]956 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]957</ul>
958
959</div>
960
961<!-- ======================================================================= -->
962<div class="doc_subsection">
963 <a name="ppc-be">Known problems with the PowerPC back-end</a>
964</div>
965
966<div class="doc_text">
967
968<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]969<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]970compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]971</ul>
972
973</div>
974
975<!-- ======================================================================= -->
976<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]977 <a name="arm-be">Known problems with the ARM back-end</a>
978</div>
979
980<div class="doc_text">
981
982<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]983<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]984processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]985results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]986<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]987</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]988</ul>
989
990</div>
991
992<!-- ======================================================================= -->
993<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]994 <a name="sparc-be">Known problems with the SPARC back-end</a>
995</div>
996
997<div class="doc_text">
998
999<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1000<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]1001 support the 64-bit SPARC ABI (-m64).</li>
1002</ul>
1003
1004</div>
1005
1006<!-- ======================================================================= -->
1007<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1008 <a name="mips-be">Known problems with the MIPS back-end</a>
1009</div>
1010
1011<div class="doc_text">
1012
1013<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1014<li>64-bit MIPS targets are not supported yet.</li>
1015</ul>
1016
1017</div>
1018
1019<!-- ======================================================================= -->
1020<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1021 <a name="alpha-be">Known problems with the Alpha back-end</a>
1022</div>
1023
1024<div class="doc_text">
1025
1026<ul>
1027
1028<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1029appropriate nops inserted to ensure restartability.</li>
1030
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1031</ul>
1032</div>
1033
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1034<!-- ======================================================================= -->
1035<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1036 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1037</div>
1038
1039<div class="doc_text">
1040
1041<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1042<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1043 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1044<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1045 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1046 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1047<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1048<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1049</ul>
1050
1051</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1052
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1053
1054<!-- ======================================================================= -->
1055<div class="doc_subsection">
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]1056 <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]1057</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1058
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1059<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1060
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1061<p>The only major language feature of GCC not supported by llvm-gcc is
1062 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1063 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1064 supported on some targets (these are used when you take the address of a
1065 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1066
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1067</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1068
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1069<!-- ======================================================================= -->
1070<div class="doc_subsection">
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1071 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1072</div>
1073
1074<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1075<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1076<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1077 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1078 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1079</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1080</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1081
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1082<!-- ======================================================================= -->
1083<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1084 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1085</div>
1086
1087<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1088The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1089technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1090<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1091<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]1092to lack of trampoline support (pointers to nested functions) on other platforms.
1093However, 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]1094which does support trampolines.</li>
1095<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]1096This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1097exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1098Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1099<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1100and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1101(c380004 also fails with gcc-4.2 mainline).
1102If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1103causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1104<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1105<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1106<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]1107crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1108<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1109or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1110or use representation clauses that result in a field of a non-discrete type
1111starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1112<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1113'main' as generated by the Ada binder to be invalid</a>.
1114Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1115<tt>envp</tt> rather than integers.</li>
1116<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1117ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1118</ul>
1119</div>
1120
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1121<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1122<div class="doc_section">
1123 <a name="additionalinfo">Additional Information</a>
1124</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1125<!-- *********************************************************************** -->
1126
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1127<div class="doc_text">
1128
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1129<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1130href="http://llvm.org">LLVM web page</a>, in particular in the <a
1131href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1132contains versions of the API documentation which is up-to-date with the
1133Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1134You can access versions of these documents specific to this release by going
1135into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1136
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1137<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]1138us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1139lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1140
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1141</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1142
1143<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1144
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1145<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1146<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1147 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1148 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1149 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1150 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]1151
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1152 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1153 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1154</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1155
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1156</body>
1157</html>