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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / e2c06b646a84d1e09ee327ecbfb3309a09b7fc5d / . / docs / ReleaseNotes.html
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Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]7 <title>LLVM 2.7 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]11<div class="doc_title">LLVM 2.7 Release Notes</div>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]12
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]13<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]14 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]15
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]16<ol>
17 <li><a href="#intro">Introduction</a></li>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]18 <li><a href="#subproj">Sub-project Status Update</a></li>
Jeffrey Yasskin8ee1b0a2010-01-28 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]21 <li><a href="GettingStarted.html">Installation Instructions</a></li>
22 <li><a href="#portability">Portability and Supported Platforms</a></li>
Dan Gohman0de549c2008-10-14 16:23:02 +0000[diff] [blame]23 <li><a href="#knownproblems">Known Problems</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]24 <li><a href="#additionalinfo">Additional Information</a></li>
25</ol>
26
27<div class="doc_author">
Dan Gohman0de549c2008-10-14 16:23:02 +0000[diff] [blame]28 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]29</div>
30
Chris Lattner6ba1be32010-04-13 06:37:00 +0000[diff] [blame]31<!--
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]32<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]33release.<br>
34You may prefer the
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]35<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.7
Chris Lattner6ba1be32010-04-13 06:37:00 +0000[diff] [blame]36Release Notes</a>.</h1>-->
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]37
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]38<!-- *********************************************************************** -->
39<div class="doc_section">
40 <a name="intro">Introduction</a>
41</div>
42<!-- *********************************************************************** -->
43
44<div class="doc_text">
45
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]46<p>This document contains the release notes for the LLVM Compiler
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]47Infrastructure, release 2.7. Here we describe the status of LLVM, including
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]48major improvements from the previous release and significant known problems.
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]49All LLVM releases may be downloaded from the <a
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]50href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]51
52<p>For more information about LLVM, including information about the latest
53release, please check out the <a href="http://llvm.org/">main LLVM
54web site</a>. If you have questions or comments, the <a
Chris Lattner58b1d0f2010-03-17 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]57
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]58<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]59main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif7c65c4f2008-10-14 11:00:32 +0000[diff] [blame]60current one. To see the release notes for a specific release, please see the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]61<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]62
63</div>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]64
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]65
Chris Lattner0b6ea7a2009-10-13 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 Lattner6ba1be32010-04-13 06:37:00 +0000[diff] [blame]71 ABCD, GEPSplitterPass
Chris Lattner2bd5e652010-01-16 21:25:13 +0000[diff] [blame]72 MSIL backend?
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]73 lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]74-->
75
76
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]77<!-- Features that need text if they're finished for 2.7:
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]78 combiner-aa?
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]79 strong phi elim
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]80 llvm.dbg.value: variable debug info for optimized code
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]81 loop dependence analysis
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]82 -->
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]83
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame]84 <!-- for announcement email:
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]85 Logo web page.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]86 Many new papers added to /pubs/
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]87 -->
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]88
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]89<!-- *********************************************************************** -->
90<div class="doc_section">
91 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]92</div>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]93<!-- *********************************************************************** -->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]94
95<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]96<p>
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]97The LLVM 2.7 distribution currently consists of code from the core LLVM
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]98repository (which roughly includes the LLVM optimizers, code generators
99and supporting tools), the Clang repository and the llvm-gcc repository. In
100addition to this code, the LLVM Project includes other sub-projects that are in
101development. Here we include updates on these subprojects.
Bill Wendlingdde41b82009-03-02 04:28:57 +0000[diff] [blame]102</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]103
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]104</div>
105
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]106
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]107<!--=========================================================================-->
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]108<div class="doc_subsection">
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]109<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]110</div>
111
112<div class="doc_text">
113
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]114<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
115C++, and Objective-C languages. Clang aims to provide a better user experience
116through expressive diagnostics, a high level of conformance to language
117standards, fast compilation, and low memory use. Like LLVM, Clang provides a
118modular, library-based architecture that makes it suitable for creating or
119integrating with other development tools. Clang is considered a
120production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]121
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]122<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]123
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]124<ul>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]125
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]126<li>C++ Support: Clang is now capable of self-hosting! While still
127alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang,
128and C++ is now enabled by default. See the <a
129href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility
130page</a> for common C++ migration issues.</li>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]131
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]132<li>Objective-C: Clang now includes experimental support for an updated
133Objective-C ABI on non-Darwin platforms. This includes support for non-fragile
134instance variables and accelerated proxies, as well as greater potential for
135future optimisations. The new ABI is used when compiling with the
136-fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these
137options may be mixed with code compiled with GCC or clang using the old GNU ABI,
138but requires the libobjc2 runtime from the GNUstep project.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]139
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]140<li>New warnings: Clang contains a number of new warnings, including
141control-flow warnings (unreachable code, missing return statements in a
142non-<code>void</code> function, etc.), sign-comparison warnings, and improved
143format-string warnings.</li>
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]144
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]145<li>CIndex API and Python bindings: Clang now includes a C API as part of the
Gabor Greif8abc1962010-04-25 21:27:54 +0000[diff] [blame]146CIndex library. Although we may make some changes to the API in the future, it
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]147is intended to be stable and has been designed for use by external projects. See
148the Clang
149doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
Wesley Peck43e93692010-04-22 14:19:00 +0000[diff] [blame]150documentation for more details. The CIndex API also includes a preliminary
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]151set of Python bindings.</li>
152
153<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
154ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
Gabor Greif8abc1962010-04-25 21:27:54 +0000[diff] [blame]155suitable for use as a beta quality ARM compiler.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]156
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]157</ul>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]158</div>
159
160<!--=========================================================================-->
161<div class="doc_subsection">
162<a name="clangsa">Clang Static Analyzer</a>
163</div>
164
165<div class="doc_text">
166
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]167<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
168 project is an effort to use static source code analysis techniques to
169 automatically find bugs in C and Objective-C programs (and hopefully <a
170 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
171 future</a>!). The tool is very good at finding bugs that occur on specific
172 paths through code, such as on error conditions.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]173
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]174<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
175 minor improvements, including better support for tracking the fields of
176 structures, initial support (not enabled by default yet) for doing
177 interprocedural (cross-function) analysis, and new checks have been added.
178</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]179
180</div>
181
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]182<!--=========================================================================-->
183<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]184<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]185</div>
186
187<div class="doc_text">
188<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]189The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]190a JVM and a CLI Virtual Machine (Microsoft .NET is an
191implementation of the CLI) using LLVM for static and just-in-time
192compilation.</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]193
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]194<p>
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]195With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
196virtual machines. VMKit now offers precise and efficient garbage collection with
197multi-threading support, thanks to the MMTk memory management toolkit, as well
198as just in time and ahead of time compilation with LLVM. The major changes in
199VMKit 0.27 are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]200
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]201<ul>
202
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]203<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
204 The first collector to be ported is the MarkSweep collector, which is precise,
205 and drastically improves the performance of VMKit.</li>
206<li>Line number information in the JVM: by using the debug metadata of LLVM, the
207 JVM now supports precise line number information, useful when printing a stack
208 trace.</li>
209<li>Interface calls in the JVM: we implemented a variant of the Interface Method
210 Table technique for interface calls in the JVM.
211</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]212
213</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]214</div>
215
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]216
217<!--=========================================================================-->
218<div class="doc_subsection">
219<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
220</div>
221
222<div class="doc_text">
223<p>
224The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
225is a simple library that provides an implementation of the low-level
226target-specific hooks required by code generation and other runtime components.
227For example, when compiling for a 32-bit target, converting a double to a 64-bit
228unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
229function. The compiler-rt library provides highly optimized implementations of
230this and other low-level routines (some are 3x faster than the equivalent
231libgcc routines).</p>
232
233<p>
234All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]235License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
236supports ARM targets.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]237
238</div>
239
240<!--=========================================================================-->
241<div class="doc_subsection">
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]242<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]243</div>
244
245<div class="doc_text">
246<p>
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]247<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
248gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
249gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
250whatsoever (currently one small patch is needed). This is thanks to the new
251<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
252makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
253which is nothing more than a dynamic library which conforms to the gcc plugin
254interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
255instead of the gcc optimizers, and the LLVM code generators instead of the gcc
256code generators, just like llvm-gcc. To use it, you add
257"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
258becomes llvm-gcc-4.5!
259</p>
260
261<p>
262DragonEgg is still a work in progress. Currently C works very well, while C++,
263Ada and Fortran work fairly well. All other languages either don't work at all,
264or only work poorly. For the moment only the x86-32 and x86-64 targets are
Duncan Sands566f40b2010-04-20 19:40:58 +0000[diff] [blame]265supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]266</p>
267
268<p>
Duncan Sandsa9cc3892010-04-21 13:51:48 +0000[diff] [blame]269DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]270</p>
271
272</div>
273
274
275<!--=========================================================================-->
276<div class="doc_subsection">
277<a name="mc">llvm-mc: Machine Code Toolkit</a>
278</div>
279
280<div class="doc_text">
281<p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]282The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
283of problems in the realm of assembly, disassembly, object file format handling,
284and a number of other related areas that CPU instruction-set level tools work
285in. It is a sub-project of LLVM which provides it with a number of advantages
286over other compilers that do not have tightly integrated assembly-level tools.
287For a gentle introduction, please see the <a
288href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
289LLVM MC Project Blog Post</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]290</p>
291
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]292<p>2.7 includes major parts of the work required by the new MC Project. A few
293 targets have been refactored to support it, and work is underway to support a
Gabor Greif9e25ea72010-04-25 21:30:22 +0000[diff] [blame]294 native assembler in LLVM. This work is not complete in LLVM 2.7, but it has
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]295 made substantially more progress on LLVM mainline.</p>
296
297<p>One minor example of what MC can do is to transcode an AT&amp;T syntax
Gabor Greifadba54d2010-04-22 10:25:23 +0000[diff] [blame]298 X86 .s file into intel syntax. You can do this with something like:</p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]299<pre>
300 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
301</pre>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]302
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]303</div>
304
305
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]306<!-- *********************************************************************** -->
307<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]308 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]309</div>
310<!-- *********************************************************************** -->
311
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]312<div class="doc_text">
313
314<p>An exciting aspect of LLVM is that it is used as an enabling technology for
315 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]316 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]317</div>
318
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]319<!--=========================================================================-->
320<div class="doc_subsection">
321<a name="pure">Pure</a>
322</div>
323
324<div class="doc_text">
325<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]326<a href="http://pure-lang.googlecode.com/">Pure</a>
327is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]328Programs are collections of equations which are used to evaluate expressions in
329a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]330lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]331built-in list and matrix support (including list and matrix comprehensions) and
332an easy-to-use C interface. The interpreter uses LLVM as a backend to
333 JIT-compile Pure programs to fast native code.</p>
334
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]335<p>Pure versions 0.43 and later have been tested and are known to work with
336LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
337
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]338</div>
339
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]340<!--=========================================================================-->
341<div class="doc_subsection">
342<a name="RoadsendPHP">Roadsend PHP</a>
343</div>
344
345<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]346<p>
347<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattner9e08de12009-03-02 19:07:24 +0000[diff] [blame]348source implementation of the PHP programming
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]349language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]350reimplementation of an earlier project that is now based on LLVM.
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]351</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]352</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]353
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]354<!--=========================================================================-->
355<div class="doc_subsection">
356<a name="UnladenSwallow">Unladen Swallow</a>
357</div>
358
359<div class="doc_text">
360<p>
361<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
362branch of <a href="http://python.org/">Python</a> intended to be fully
363compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerd7db82c2010-03-18 06:52:15 +0000[diff] [blame]364compiler.
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]365</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]366</div>
367
368<!--=========================================================================-->
369<div class="doc_subsection">
Chris Lattner49894862010-03-29 17:50:39 +0000[diff] [blame]370<a name="tce">TTA-based Codesign Environment (TCE)</a>
371</div>
372
373<div class="doc_text">
374<p>
375<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
376application-specific processors (ASP) based on the Transport triggered
377architecture (TTA). The toolset provides a complete co-design flow from C/C++
378programs down to synthesizable VHDL and parallel program binaries. Processor
379customization points include the register files, function units, supported
380operations, and the interconnection network.</p>
381
382<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
383independent optimizations and also for parts of code generation. It generates
384new LLVM-based code generators "on the fly" for the designed TTA processors and
385loads them in to the compiler backend as runtime libraries to avoid per-target
386recompilation of larger parts of the compiler chain.</p>
387
388</div>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]389
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]390<!--=========================================================================-->
391<div class="doc_subsection">
392<a name="safecode">SAFECode Compiler</a>
393</div>
394
395<div class="doc_text">
396<p>
397<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
398compiler built using LLVM. It takes standard, unannotated C code, analyzes the
399code to ensure that memory accesses and array indexing operations are safe, and
400instruments the code with run-time checks when safety cannot be proven
401statically.
402</p>
403</div>
404
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]405<!--=========================================================================-->
406<div class="doc_subsection">
407<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
408</div>
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]409
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]410<div class="doc_text">
411<p>
412<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
413harness to build OpenJDK using only free software build tools and to provide
414replacements for the not-yet free parts of OpenJDK. One of the extensions that
415IcedTea provides is a new JIT compiler named <a
416href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
417to provide native code generation without introducing processor-dependent
418code.
419</p>
420<p>Icedtea6 1.8 and later have been tested and are known to work with
421LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
422</p>
423</div>
424
425<!--=========================================================================-->
426<div class="doc_subsection">
427<a name="llvm-lua">LLVM-Lua</a>
428</div>
429
430<div class="doc_text">
431<p>
432<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
433 to add JIT and static compiling support to the Lua VM. Lua
434bytecode is analyzed to remove type checks, then LLVM is used to compile the
435bytecode down to machine code.
436</p>
437<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
438</p>
439</div>
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]440
441<!--=========================================================================-->
442<div class="doc_subsection">
443<a name="MacRuby">MacRuby</a>
444</div>
445
446<div class="doc_text">
447<p>
448<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on
449core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for
450optimization passes, JIT compilation and exception handling. It also allows
451static (ahead-of-time) compilation of Ruby code straight to machine code.
452</p>
453<p>The upcoming MacRuby 0.6 release works with LLVM 2.7.
454</p>
455</div>
456
Chris Lattner745cf9f2010-04-26 17:38:10 +0000[diff] [blame]457<!--=========================================================================-->
458<div class="doc_subsection">
459<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
460</div>
461
462<div class="doc_text">
463<p>
464<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
465state-of-the-art programming suite for Haskell, a standard lazy
466functional programming language. It includes an optimizing static
467compiler generating good code for a variety of platforms, together
468with an interactive system for convenient, quick development.</p>
469
470<p>In addition to the existing C and native code generators, GHC now
471supports an <a
472href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
473code generator</a>. GHC supports LLVM 2.7.</p>
474
475</div>
476
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]477
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]478<!-- *********************************************************************** -->
479<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]480 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]481</div>
482<!-- *********************************************************************** -->
483
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]484<div class="doc_text">
485
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]486<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]487minor improvements. Some of the major improvements and new features are listed
488in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]489</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]490
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]491</div>
492
493<!--=========================================================================-->
494<div class="doc_subsection">
495<a name="orgchanges">LLVM Community Changes</a>
496</div>
497
498<div class="doc_text">
499
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]500<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
501organization changes have happened:
502</p>
503
504<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]505<li>LLVM has a new <a href="http://llvm.org/Logo.html">official logo</a>!</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]506
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]507<li>Ted Kremenek and Doug Gregor have stepped forward as <a
508 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]509 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]510
511<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
512 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
513 to learn about new LLVM-related features as they are implemented. Several
514 features in this release are already explained on the blog.</li>
515
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]516<li>The LLVM web pages are now checked into the SVN server, in the "www",
517 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]518 largely inaccessible old CVS server.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]519
520<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
521 faster) server. It is still graciously hosted at the University of Illinois
522 of Urbana Champaign.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]523</ul>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]524</div>
525
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]526<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]527<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]528<a name="majorfeatures">Major New Features</a>
529</div>
530
531<div class="doc_text">
532
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]533<p>LLVM 2.7 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]534
535<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]536<li>2.7 includes initial support for the <a
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]537 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
538 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]539
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]540<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]541 supports many different use cases, including allowing front-end authors to
542 encode source level information into LLVM IR, which is consumed by later
543 language-specific passes. This is a great way to do high-level optimizations
544 like devirtualization, type-based alias analysis, etc. See the <a
545 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
546 Extensible Metadata Blog Post</a> for more information.</li>
547
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]548<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]549in a completely new way, built on extensible metadata. The new implementation
550is much more memory efficient and paves the way for improvements to optimized
551code debugging experience.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]552
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]553<li>2.7 now directly supports taking the address of a label and doing an
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]554 indirect branch through a pointer. This is particularly useful for
555 interpreter loops, and is used to implement the GCC "address of label"
556 extension. For more information, see the <a
557href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
558Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]559
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]560<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]561 disassembling target machine code. These APIs are useful for a variety of
562 low level clients, and are surfaced in the new "enhanced disassembly" API.
563 For more information see the <a
564 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
565 Disassembler Blog Post</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]566
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]567<li>2.7 includes major parts of the work required by the new MC Project,
568 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]569
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]570</ul>
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]571
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]572</div>
573
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]574<!--=========================================================================-->
575<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]576<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]577</div>
578
579<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]580<p>LLVM IR has several new features for better support of new targets and that
581expose new optimization opportunities:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]582
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]583<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]584<li>LLVM IR now supports a 16-bit "half float" data type through <a
585 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
586<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]587 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]588 optimizer that a function was declared 'inline' and thus the inliner should
589 weight it higher when considering inlining it. The later
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]590 indicates to the code generator that the function diverges from the platform
591 ABI on stack alignment.</li>
592<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
593 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]594 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]595 extension.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]596<li>LLVM IR now supports marking load and store instructions with <a
597 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
598 metadata feature). This hint encourages the code
599 generator to generate non-temporal accesses when possible, which are useful
600 for code that is carefully managing cache behavior. Currently, only the
601 X86 backend provides target support for this feature.</li>
602
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]603<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifdd39cd12010-04-22 10:11:24 +0000[diff] [blame]604 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]605 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]606 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]607
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]608</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]609
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]610</div>
611
612<!--=========================================================================-->
613<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]614<a name="optimizer">Optimizer Improvements</a>
615</div>
616
617<div class="doc_text">
618
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]619<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]620release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]621
622<ul>
623
Chris Lattnerbf1bb302010-04-27 07:28:11 +0000[diff] [blame]624<li>The inliner now merges arrays stack objects in different callees when
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]625 inlining multiple call sites into one function. This reduces the stack size
626 of the resultant function.</li>
627<li>The -basicaa alias analysis pass (which is the default) has been improved to
628 be less dependent on "type safe" pointers. It can now look through bitcasts
629 and other constructs more aggressively, allowing better load/store
630 optimization.</li>
631<li>The load elimination optimization in the GVN Pass [<a
632href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
633 blog post</a>] has been substantially improved to be more aggressive about
634 partial redundancy elimination and do more aggressive phi translation. Please
635 see the <a
636 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
637 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
638 Blog Post</a> for more details.</li>
639<li>The module <a href="LangRef.html#datalayout">target data string</a> now
Wesley Peck63c86992010-04-22 13:28:34 +0000[diff] [blame]640 includes a notion of 'native' integer data types for the target. This
641 helps mid-level optimizations avoid promoting complex sequences of
642 operations to data types that are not natively supported (e.g. converting
643 i32 operations to i64 on 32-bit chips).</li>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]644<li>The mid-level optimizer is now conservative when operating on a module with
645 no target data. Previously, it would default to SparcV9 settings, which is
646 not what most people expected.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]647<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]648 conditionals and threading blocks with otherwise complex logic. It has
649 subsumed the old "Conditional Propagation" pass, and -condprop has been
650 removed from LLVM 2.7.</li>
651<li>The -instcombine pass has been refactored from being one huge file to being
652 a library of its own. Internally, it uses a customized IRBuilder to clean
653 it up and simplify it.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]654
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]655<li>The optimal edge profiling pass is reliable and much more complete than in
656 2.6. It can be used with the llvm-prof tool but isn't wired up to the
657 llvm-gcc and clang command line options yet.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]658
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]659<li>A new experimental alias analysis implementation, -scev-aa, has been added.
660 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
661 pointer offset expressions to disambiguate pointers. It can catch a few
662 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]663
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]664<li>The default pass ordering has been tweaked for improved optimization
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]665 effectiveness.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]666
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]667</ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]668
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]669</div>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]670
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]671
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]672<!--=========================================================================-->
673<div class="doc_subsection">
674<a name="executionengine">Interpreter and JIT Improvements</a>
675</div>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]676
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]677<div class="doc_text">
678
679<ul>
Wesley Peck0d7f61e2010-04-22 13:36:27 +0000[diff] [blame]680<li>The JIT now supports generating debug information and is compatible with
681the new GDB 7.0 (and later) interfaces for registering dynamically generated
682debug info.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]683
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]684<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin40715142010-01-29 19:10:38 +0000[diff] [blame]685to compiling eagerly</a> to avoid a race condition in the lazy JIT.
686Clients that still want the lazy JIT can switch it on by calling
687<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]688
Jeffrey Yasskinc0577082010-02-11 01:07:39 +0000[diff] [blame]689<li>It is now possible to create more than one JIT instance in the same process.
690These JITs can generate machine code in parallel,
691although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
692still have to obey the other threading restrictions</a>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]693
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]694</ul>
695
696</div>
697
698<!--=========================================================================-->
699<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]700<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]701</div>
702
703<div class="doc_text">
704
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]705<p>We have put a significant amount of work into the code generator
706infrastructure, which allows us to implement more aggressive algorithms and make
707it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]708
709<ul>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]710<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
711 to emit many useful comments to .s files indicating information about spill
712 slots and loop nest structure. This should make it much easier to read and
713 understand assembly files. This is wired up in llvm-gcc and clang to
714 the <tt>-fverbose-asm</tt> option.</li>
715
Dan Gohman93087ff2010-04-22 20:50:43 +0000[diff] [blame]716<li>New LSR with "full strength reduction" mode, which can reduce address
717 register pressure in loops where address generation is important.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]718
719<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
720 is available and enabled by default. It catches redundancies exposed by
721 lowering.</li>
722<li>A new pre-register-allocation tail duplication pass is available and enabled
723 by default, it can substantially improve branch prediction quality in some
724 cases.</li>
725<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
726 is available and enabled by default. This pass can takes advantage
727 architecture features like x86-64 implicit zero extension behavior and
728 sub-registers.</li>
729<li>The code generator now supports a mode where it attempts to preserve the
730 order of instructions in the input code. This is important for source that
731 is hand scheduled and extremely sensitive to scheduling. It is compatible
732 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
733<li>The target-independent code generator now supports generating code with
734 arbitrary numbers of result values. Returning more values than was
735 previously supported is handled by returning through a hidden pointer. In
736 2.7, only the X86 and XCore targets have adopted support for this
737 though.</li>
738<li>The code generator now supports generating code that follows the
739 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
740 Convention</a> and ABI.</li>
741<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
742 selection</a>" phase of the code generator has been largely rewritten for
743 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
744 linked into the target to do the pattern matching, now it emits a much
745 smaller table which is read by the target-independent code. The primary
746 advantages of this approach is that the size and compile time of various
747 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
748 for example.</li>
749<li>Almost the entire code generator has switched to emitting code through the
750 MC interfaces instead of printing textually to the .s file. This led to a
751 number of cleanups and speedups. In 2.7, debug an exception handling
752 information does not go through MC yet.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]753</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]754</div>
755
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]756<!--=========================================================================-->
757<div class="doc_subsection">
758<a name="x86">X86-32 and X86-64 Target Improvements</a>
759</div>
760
761<div class="doc_text">
762<p>New features of the X86 target include:
763</p>
764
765<ul>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]766<li>The X86 backend now optimizes tails calls much more aggressively for
767 functions that use the standard C calling convention.</li>
768<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
769 registers, making the code generator more aggressive in cases where scalars
770 and vector types are mixed.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]771
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]772</ul>
773
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]774</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]775
776<!--=========================================================================-->
777<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]778<a name="ARM">ARM Target Improvements</a>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]779</div>
780
781<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]782<p>New features of the ARM target include:
783</p>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]784
785<ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]786
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]787<li>The ARM backend now generates instructions in unified assembly syntax.</li>
788
789<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
790 support differs slightly from the GCC implementation. Please see the
791 <a
792href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
793 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
794 helpful information if migrating code from GCC to LLVM-GCC.</li>
795
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]796<li>The ARM and Thumb code generators now use register scavenging for stack
Jim Grosbachc5595772010-04-22 18:28:43 +0000[diff] [blame]797 object address materialization. This allows the use of R3 as a general
798 purpose register in Thumb1 code, as it was previous reserved for use in
799 stack address materialization. Secondly, sequential uses of the same
800 value will now re-use the materialized constant.</li>
801
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]802<li>The ARM backend now has good support for ARMv4 targets and has been tested
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]803 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
804 newer chips.</li>
Jim Grosbach95254a42010-04-22 18:33:31 +0000[diff] [blame]805
806<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize,
807 __sync_fetch_and_add, etc.).</li>
808
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]809</ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]810
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]811
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]812</div>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]813
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]814<!--=========================================================================-->
815<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]816<a name="newapis">New Useful APIs</a>
817</div>
818
819<div class="doc_text">
820
821<p>This release includes a number of new APIs that are used internally, which
822 may also be useful for external clients.
823</p>
824
825<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]826<li>The optimizer uses the new CodeMetrics class to measure the size of code.
Chris Lattner9d966ed2010-04-22 17:39:38 +0000[diff] [blame]827 Various passes (like the inliner, loop unswitcher, etc) all use this to make
828 more accurate estimates of the code size impact of various
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]829 optimizations.</li>
830<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]831 llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]832 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
833 without requiring the instruction to exist. This centralizes a lot of
834 ad-hoc symbolic manipulation code scattered in various passes.</li>
835<li>The optimizer now uses a new <a
836 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
837 class which efficiently supports
838 doing unstructured SSA update operations. This centralized a bunch of code
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]839 scattered throughout various passes (e.g. jump threading, lcssa,
840 loop rotate, etc) for doing this sort of thing. The code generator has a
841 similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]842 MachineSSAUpdater</a> class.</li>
843<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
844 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]845 expression API. Building on this, the <a
846 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
847 regular exressions.</li>
848<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
849 By default, this stream works the same way as "errs()", but if you pass
850 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
851 fixed sized circular buffer and the output is printed at the end of the
852 program's execution. This is helpful if you have a long lived compiler
853 process and you're interested in seeing snapshots in time.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]854</ul>
855
856
857</div>
858
859<!--=========================================================================-->
860<div class="doc_subsection">
861<a name="otherimprovements">Other Improvements and New Features</a>
862</div>
863
864<div class="doc_text">
865<p>Other miscellaneous features include:</p>
866
867<ul>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]868<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
869 get this, configure LLVM with the --enable-shared option.</li>
870
Wesley Pecka85292d2010-04-22 13:53:54 +0000[diff] [blame]871<li>LLVM command line tools now overwrite their output by default. Previously,
872 they would only do this with -f. This makes them more convenient to use, and
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]873 behave more like standard unix tools.</li>
874
875<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
876 file, and automatically do the right thing. This means you don't need to
877 explicitly use the llvm-as tool for most things.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]878</ul>
879
880</div>
881
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]882
883<!--=========================================================================-->
884<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]885<a name="changes">Major Changes and Removed Features</a>
886</div>
887
888<div class="doc_text">
889
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]890<p>If you're already an LLVM user or developer with out-of-tree changes based
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]891on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]892from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]893
894<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]895
896<li>
897The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
898("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
899profiling ("rsprofiling") passes have all been removed. They were not being
900actively maintained and had substantial problems. If you are interested in
901these components, you are welcome to ressurect them from SVN, fix the
902correctness problems, and resubmit them to mainline.</li>
903
904<li>LLVM now defaults to building most libraries with RTTI turned off, providing
905a code size reduction. Packagers who are interested in building LLVM to support
906plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
907and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
908document.</li>
909
Jeffrey Yasskin260af332010-02-09 23:03:44 +0000[diff] [blame]910<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
911if you have it installed. This makes it more likely that an LLVM built on one
912system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]913configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]914
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]915<li>Debug information uses a completely different representation, an LLVM 2.6
916.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
917
918<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
919 along with LowerAllocations pass. Now you should just use a call to the
920 malloc and free functions in libc. These calls are optimized as well as
921 the old instructions were.</li>
922</ul>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]923
924<p>In addition, many APIs have changed in this release. Some of the major LLVM
925API changes are:</p>
926
927<ul>
Gabor Greif3f98acb2010-04-26 20:46:03 +0000[diff] [blame]928<li>Just about everything has been converted to use <tt>raw_ostream</tt> instead of
929 <tt>std::ostream</tt>.</li>
930<li><tt>llvm/ADT/iterator.h</tt> has been removed, just use <tt>&lt;iterator&gt;</tt>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]931 instead.</li>
Gabor Greif3f98acb2010-04-26 20:46:03 +0000[diff] [blame]932<li>The <tt>Streams.h</tt> file and <tt>DOUT</tt> got removed, use <tt>DEBUG(errs() &lt;&lt; ...);</tt>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]933 instead.</li>
Gabor Greif3f98acb2010-04-26 20:46:03 +0000[diff] [blame]934<li>The <tt>TargetAsmInfo</tt> interface was renamed to <tt>MCAsmInfo</tt>.</li>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]935<li><tt>ModuleProvider</tt> has been <a
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]936href="http://llvm.org/viewvc/llvm-project?view=rev&amp;revision=94686">removed</a>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]937and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
938Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
939replace <tt>getBitcodeModuleProvider</tt> with
940<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
941functions that used to accept <tt>ModuleProvider</tt>. Clients who
942wrote their own <tt>ModuleProvider</tt>s will need to derive from
943<tt>GVMaterializer</tt> instead and use
944<tt>Module::setMaterializer</tt> to attach it to a
945<tt>Module</tt>.</li>
946
947<li><tt>GhostLinkage</tt> has given up the ghost.
948<tt>GlobalValue</tt>s that have not yet been read from their backing
949storage have the same linkage they will have after being read in.
950Clients must replace calls to
951<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
952<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar61f41422010-02-10 04:09:52 +0000[diff] [blame]953
Duncan Sandsdd29fc82010-02-17 17:20:17 +0000[diff] [blame]954<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
955<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
956<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
957<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]958
959<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
960<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
961 booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
962<li>Some header files have been renamed:
963<ul>
964 <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
965 <tt>llvm/System/AIXDataTypesFix.h</tt></li>
966 <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
967 <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
968 <tt>llvm/Analysis/InlineCost.h</tt></li>
969 <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
970 <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
971</ul></li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]972</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]973
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]974</div>
975
976
977
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]978<!-- *********************************************************************** -->
979<div class="doc_section">
980 <a name="portability">Portability and Supported Platforms</a>
981</div>
982<!-- *********************************************************************** -->
983
984<div class="doc_text">
985
986<p>LLVM is known to work on the following platforms:</p>
987
988<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]989<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]990 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
991 systems).</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]992<li>PowerPC and X86-based Mac OS X systems, running 10.4 and above in 32-bit
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]993 and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]994<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]995<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
996 support is available for native builds with Visual C++).</li>
Chris Lattner9235ce52009-10-16 16:30:58 +0000[diff] [blame]997<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]998<li>Alpha-based machines running Debian GNU/Linux.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]999</ul>
1000
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]1001<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1002to the machine and operating system on which it is built. However, minor
1003porting may be required to get LLVM to work on new platforms. We welcome your
1004portability patches and reports of successful builds or error messages.</p>
1005
1006</div>
1007
1008<!-- *********************************************************************** -->
1009<div class="doc_section">
1010 <a name="knownproblems">Known Problems</a>
1011</div>
1012<!-- *********************************************************************** -->
1013
1014<div class="doc_text">
1015
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]1016<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]1017listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1018href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
1019there isn't already one.</p>
1020
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]1021<ul>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1022<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
1023using the stock GCC 3.x.x series 'out the box',
Chris Lattnerc09ffd22009-11-03 21:50:09 +0000[diff] [blame]1024See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1025However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
1026for x86/x86-64 has been made available from the third party AuroraUX Project
1027that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
1028</ul>
1029
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1030</div>
1031
1032<!-- ======================================================================= -->
1033<div class="doc_subsection">
1034 <a name="experimental">Experimental features included with this release</a>
1035</div>
1036
1037<div class="doc_text">
1038
1039<p>The following components of this LLVM release are either untested, known to
1040be broken or unreliable, or are in early development. These components should
1041not be relied on, and bugs should not be filed against them, but they may be
1042useful to some people. In particular, if you would like to work on one of these
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1043components, please contact us on the <a
1044href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1045
1046<ul>
Wesley Peckbe6dc822010-03-18 14:31:30 +0000[diff] [blame]1047<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
1048 backends are experimental.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1049<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1050 supported value for this option. The MachO writer is experimental, and
1051 works much better in mainline SVN.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1052</ul>
1053
1054</div>
1055
1056<!-- ======================================================================= -->
1057<div class="doc_subsection">
1058 <a name="x86-be">Known problems with the X86 back-end</a>
1059</div>
1060
1061<div class="doc_text">
1062
1063<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]1064 <li>The X86 backend does not yet support
1065 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1066 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1067 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1068 <li>The X86 backend generates inefficient floating point code when configured
1069 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]1070 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1071 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1072 runtime currently due to lack of support for the 'u' inline assembly
1073 constraint and for X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1074 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1075 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1076 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1077</ul>
1078
1079</div>
1080
1081<!-- ======================================================================= -->
1082<div class="doc_subsection">
1083 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1084</div>
1085
1086<div class="doc_text">
1087
1088<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1089<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1090compilation, and lacks support for debug information.</li>
1091</ul>
1092
1093</div>
1094
1095<!-- ======================================================================= -->
1096<div class="doc_subsection">
1097 <a name="arm-be">Known problems with the ARM back-end</a>
1098</div>
1099
1100<div class="doc_text">
1101
1102<ul>
1103<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]1104processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1105results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1106<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1107</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1108</ul>
1109
1110</div>
1111
1112<!-- ======================================================================= -->
1113<div class="doc_subsection">
1114 <a name="sparc-be">Known problems with the SPARC back-end</a>
1115</div>
1116
1117<div class="doc_text">
1118
1119<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1120<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1121 support the 64-bit SPARC ABI (-m64).</li>
1122</ul>
1123
1124</div>
1125
1126<!-- ======================================================================= -->
1127<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1128 <a name="mips-be">Known problems with the MIPS back-end</a>
1129</div>
1130
1131<div class="doc_text">
1132
1133<ul>
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1134<li>64-bit MIPS targets are not supported yet.</li>
1135</ul>
1136
1137</div>
1138
1139<!-- ======================================================================= -->
1140<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1141 <a name="alpha-be">Known problems with the Alpha back-end</a>
1142</div>
1143
1144<div class="doc_text">
1145
1146<ul>
1147
1148<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1149appropriate nops inserted to ensure restartability.</li>
1150
1151</ul>
1152</div>
1153
1154<!-- ======================================================================= -->
1155<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1156 <a name="c-be">Known problems with the C back-end</a>
1157</div>
1158
1159<div class="doc_text">
1160
1161<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1162<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1163 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]1164<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1165 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]1166 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]1167<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]1168<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1169</ul>
1170
1171</div>
1172
1173
1174<!-- ======================================================================= -->
1175<div class="doc_subsection">
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1176 <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1177</div>
1178
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1179<div class="doc_text">
1180
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1181<p>The only major language feature of GCC not supported by llvm-gcc is
1182 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1183 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1184 supported on some targets (these are used when you take the address of a
1185 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1186
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1187</div>
1188
1189<!-- ======================================================================= -->
1190<div class="doc_subsection">
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1191 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1192</div>
1193
1194<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1195<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1196<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1197 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1198 tools/gfortran component for details.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1199</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1200</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1201
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1202<!-- ======================================================================= -->
1203<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1204 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1205</div>
1206
1207<div class="doc_text">
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1208The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1209technology, and problems should be expected.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1210<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1211<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1212to lack of trampoline support (pointers to nested functions) on other platforms.
1213However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1214which does support trampolines.</li>
1215<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]1216This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1217exception handling, which is used internally by the compiler.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1218Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]1219<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1220and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]1221(c380004 also fails with gcc-4.2 mainline).
1222If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1223causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsc2a29a02009-03-02 16:35:57 +0000[diff] [blame]1224<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1225<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1226<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1227crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1228<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1229or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1230or use representation clauses that result in a field of a non-discrete type
1231starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1232<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1233'main' as generated by the Ada binder to be invalid</a>.
1234Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1235<tt>envp</tt> rather than integers.</li>
1236<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1237ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1238</ul>
1239</div>
1240
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1241<!-- *********************************************************************** -->
1242<div class="doc_section">
1243 <a name="additionalinfo">Additional Information</a>
1244</div>
1245<!-- *********************************************************************** -->
1246
1247<div class="doc_text">
1248
1249<p>A wide variety of additional information is available on the <a
1250href="http://llvm.org">LLVM web page</a>, in particular in the <a
1251href="http://llvm.org/docs/">documentation</a> section. The web page also
1252contains versions of the API documentation which is up-to-date with the
1253Subversion version of the source code.
1254You can access versions of these documents specific to this release by going
1255into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1256
1257<p>If you have any questions or comments about LLVM, please feel free to contact
1258us via the <a href="http://llvm.org/docs/#maillist"> mailing
1259lists</a>.</p>
1260
1261</div>
1262
1263<!-- *********************************************************************** -->
1264
1265<hr>
1266<address>
1267 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1269 <a href="http://validator.w3.org/check/referer"><img
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1271
1272 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
1273 Last modified: $Date$
1274</address>
1275
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