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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 55202eaf6299c8be2aaa97697c6dfccbbbfcc81c / . / docs / ReleaseNotes.html
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Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]7 <title>LLVM 2.8 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]11<div class="doc_title">LLVM 2.8 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>
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]19 <li><a href="#externalproj">External Projects Using LLVM 2.8</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 2.8?</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 Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]31<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]32release.<br>
33You may prefer the
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]34<a href="http://llvm.org/releases/2.7/docs/ReleaseNotes.html">LLVM 2.7
35Release Notes</a>.</h1>
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]36
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]37<!-- *********************************************************************** -->
38<div class="doc_section">
39 <a name="intro">Introduction</a>
40</div>
41<!-- *********************************************************************** -->
42
43<div class="doc_text">
44
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]45<p>This document contains the release notes for the LLVM Compiler
Dan Gohman7f6a6af2010-05-03 23:52:21 +0000[diff] [blame]46Infrastructure, release 2.8. Here we describe the status of LLVM, including
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]47major improvements from the previous release and significant known problems.
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]48All LLVM releases may be downloaded from the <a
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]49href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]50
51<p>For more information about LLVM, including information about the latest
52release, please check out the <a href="http://llvm.org/">main LLVM
53web site</a>. If you have questions or comments, the <a
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]54href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
55Mailing List</a> is a good place to send them.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]56
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]57<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]58main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif7c65c4f2008-10-14 11:00:32 +0000[diff] [blame]59current one. To see the release notes for a specific release, please see the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]60<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]61
62</div>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]63
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]64
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]65<!--
66Almost dead code.
67 include/llvm/Analysis/LiveValues.h => Dan
68 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
69 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner6ba1be32010-04-13 06:37:00 +0000[diff] [blame]70 ABCD, GEPSplitterPass
Chris Lattner2bd5e652010-01-16 21:25:13 +0000[diff] [blame]71 MSIL backend?
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]72 lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]73-->
74
75
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]76<!-- Features that need text if they're finished for 2.8:
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]77 combiner-aa?
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]78 strong phi elim
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]79 llvm.dbg.value: variable debug info for optimized code
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]80 loop dependence analysis
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]81 -->
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]82
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame]83 <!-- for announcement email:
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]84 Logo web page.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]85 Many new papers added to /pubs/
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]86 -->
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]87
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]88<!-- *********************************************************************** -->
89<div class="doc_section">
90 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]91</div>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]92<!-- *********************************************************************** -->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]93
94<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]95<p>
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]96The LLVM 2.8 distribution currently consists of code from the core LLVM
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]97repository (which roughly includes the LLVM optimizers, code generators
98and supporting tools), the Clang repository and the llvm-gcc repository. In
99addition to this code, the LLVM Project includes other sub-projects that are in
100development. Here we include updates on these subprojects.
Bill Wendlingdde41b82009-03-02 04:28:57 +0000[diff] [blame]101</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]102
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]103</div>
104
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]105
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]106<!--=========================================================================-->
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]107<div class="doc_subsection">
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]108<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]109</div>
110
111<div class="doc_text">
112
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]113<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
114C++, and Objective-C languages. Clang aims to provide a better user experience
115through expressive diagnostics, a high level of conformance to language
116standards, fast compilation, and low memory use. Like LLVM, Clang provides a
117modular, library-based architecture that makes it suitable for creating or
118integrating with other development tools. Clang is considered a
119production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]120
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]121<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]122
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]123<ul>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]124
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]125<li>C++ Support: Clang is now capable of self-hosting! While still
126alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang,
127and C++ is now enabled by default. See the <a
128href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility
129page</a> for common C++ migration issues.</li>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]130
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]131<li>Objective-C: Clang now includes experimental support for an updated
132Objective-C ABI on non-Darwin platforms. This includes support for non-fragile
133instance variables and accelerated proxies, as well as greater potential for
134future optimisations. The new ABI is used when compiling with the
135-fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these
136options may be mixed with code compiled with GCC or clang using the old GNU ABI,
137but requires the libobjc2 runtime from the GNUstep project.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]138
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]139<li>New warnings: Clang contains a number of new warnings, including
140control-flow warnings (unreachable code, missing return statements in a
141non-<code>void</code> function, etc.), sign-comparison warnings, and improved
142format-string warnings.</li>
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]143
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]144<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]145CIndex library. Although we may make some changes to the API in the future, it
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]146is intended to be stable and has been designed for use by external projects. See
147the Clang
148doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
Wesley Peck43e93692010-04-22 14:19:00 +0000[diff] [blame]149documentation for more details. The CIndex API also includes a preliminary
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]150set of Python bindings.</li>
151
152<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
153ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
Gabor Greif8abc1962010-04-25 21:27:54 +0000[diff] [blame]154suitable for use as a beta quality ARM compiler.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]155
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]156</ul>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]157</div>
158
159<!--=========================================================================-->
160<div class="doc_subsection">
161<a name="clangsa">Clang Static Analyzer</a>
162</div>
163
164<div class="doc_text">
165
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]166<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
167 project is an effort to use static source code analysis techniques to
168 automatically find bugs in C and Objective-C programs (and hopefully <a
169 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
170 future</a>!). The tool is very good at finding bugs that occur on specific
171 paths through code, such as on error conditions.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]172
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]173<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
174 minor improvements, including better support for tracking the fields of
175 structures, initial support (not enabled by default yet) for doing
176 interprocedural (cross-function) analysis, and new checks have been added.
177</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]178
179</div>
180
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]181<!--=========================================================================-->
182<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]183<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]184</div>
185
186<div class="doc_text">
187<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]188The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]189a JVM and a CLI Virtual Machine (Microsoft .NET is an
190implementation of the CLI) using LLVM for static and just-in-time
191compilation.</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]192
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]193<p>
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]194With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
195virtual machines. VMKit now offers precise and efficient garbage collection with
196multi-threading support, thanks to the MMTk memory management toolkit, as well
197as just in time and ahead of time compilation with LLVM. The major changes in
198VMKit 0.27 are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]199
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]200<ul>
201
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]202<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
203 The first collector to be ported is the MarkSweep collector, which is precise,
204 and drastically improves the performance of VMKit.</li>
205<li>Line number information in the JVM: by using the debug metadata of LLVM, the
206 JVM now supports precise line number information, useful when printing a stack
207 trace.</li>
208<li>Interface calls in the JVM: we implemented a variant of the Interface Method
209 Table technique for interface calls in the JVM.
210</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]211
212</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]213</div>
214
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]215
216<!--=========================================================================-->
217<div class="doc_subsection">
218<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
219</div>
220
221<div class="doc_text">
222<p>
223The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
224is a simple library that provides an implementation of the low-level
225target-specific hooks required by code generation and other runtime components.
226For example, when compiling for a 32-bit target, converting a double to a 64-bit
227unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
228function. The compiler-rt library provides highly optimized implementations of
229this and other low-level routines (some are 3x faster than the equivalent
230libgcc routines).</p>
231
232<p>
233All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]234License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
235supports ARM targets.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]236
237</div>
238
239<!--=========================================================================-->
240<div class="doc_subsection">
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]241<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]242</div>
243
244<div class="doc_text">
245<p>
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]246<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
247gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
248gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
249whatsoever (currently one small patch is needed). This is thanks to the new
250<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
251makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
252which is nothing more than a dynamic library which conforms to the gcc plugin
253interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
254instead of the gcc optimizers, and the LLVM code generators instead of the gcc
255code generators, just like llvm-gcc. To use it, you add
256"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
257becomes llvm-gcc-4.5!
258</p>
259
260<p>
261DragonEgg is still a work in progress. Currently C works very well, while C++,
262Ada and Fortran work fairly well. All other languages either don't work at all,
263or 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]264supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]265</p>
266
267<p>
Duncan Sandsa9cc3892010-04-21 13:51:48 +0000[diff] [blame]268DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]269</p>
270
271</div>
272
273
274<!--=========================================================================-->
275<div class="doc_subsection">
276<a name="mc">llvm-mc: Machine Code Toolkit</a>
277</div>
278
279<div class="doc_text">
280<p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]281The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
282of problems in the realm of assembly, disassembly, object file format handling,
283and a number of other related areas that CPU instruction-set level tools work
284in. It is a sub-project of LLVM which provides it with a number of advantages
285over other compilers that do not have tightly integrated assembly-level tools.
286For a gentle introduction, please see the <a
287href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
288LLVM MC Project Blog Post</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]289</p>
290
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]291<p>2.7 includes major parts of the work required by the new MC Project. A few
292 targets have been refactored to support it, and work is underway to support a
Gabor Greif9e25ea72010-04-25 21:30:22 +0000[diff] [blame]293 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]294 made substantially more progress on LLVM mainline.</p>
295
296<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]297 X86 .s file into intel syntax. You can do this with something like:</p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]298<pre>
299 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
300</pre>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]301
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]302</div>
303
304
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]305<!-- *********************************************************************** -->
306<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]307 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]308</div>
309<!-- *********************************************************************** -->
310
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]311<div class="doc_text">
312
313<p>An exciting aspect of LLVM is that it is used as an enabling technology for
314 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]315 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]316</div>
317
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]318<!--=========================================================================-->
319<div class="doc_subsection">
320<a name="pure">Pure</a>
321</div>
322
323<div class="doc_text">
324<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]325<a href="http://pure-lang.googlecode.com/">Pure</a>
326is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]327Programs are collections of equations which are used to evaluate expressions in
328a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]329lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]330built-in list and matrix support (including list and matrix comprehensions) and
331an easy-to-use C interface. The interpreter uses LLVM as a backend to
332 JIT-compile Pure programs to fast native code.</p>
333
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]334<p>Pure versions 0.43 and later have been tested and are known to work with
335LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
336
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]337</div>
338
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]339<!--=========================================================================-->
340<div class="doc_subsection">
341<a name="RoadsendPHP">Roadsend PHP</a>
342</div>
343
344<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]345<p>
346<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattner9e08de12009-03-02 19:07:24 +0000[diff] [blame]347source implementation of the PHP programming
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]348language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]349reimplementation of an earlier project that is now based on LLVM.
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]350</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]351</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]352
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]353<!--=========================================================================-->
354<div class="doc_subsection">
355<a name="UnladenSwallow">Unladen Swallow</a>
356</div>
357
358<div class="doc_text">
359<p>
360<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
361branch of <a href="http://python.org/">Python</a> intended to be fully
362compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerd7db82c2010-03-18 06:52:15 +0000[diff] [blame]363compiler.
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]364</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]365</div>
366
367<!--=========================================================================-->
368<div class="doc_subsection">
Chris Lattner49894862010-03-29 17:50:39 +0000[diff] [blame]369<a name="tce">TTA-based Codesign Environment (TCE)</a>
370</div>
371
372<div class="doc_text">
373<p>
374<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
375application-specific processors (ASP) based on the Transport triggered
376architecture (TTA). The toolset provides a complete co-design flow from C/C++
377programs down to synthesizable VHDL and parallel program binaries. Processor
378customization points include the register files, function units, supported
379operations, and the interconnection network.</p>
380
381<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
382independent optimizations and also for parts of code generation. It generates
383new LLVM-based code generators "on the fly" for the designed TTA processors and
384loads them in to the compiler backend as runtime libraries to avoid per-target
385recompilation of larger parts of the compiler chain.</p>
386
387</div>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]388
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]389<!--=========================================================================-->
390<div class="doc_subsection">
391<a name="safecode">SAFECode Compiler</a>
392</div>
393
394<div class="doc_text">
395<p>
396<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
397compiler built using LLVM. It takes standard, unannotated C code, analyzes the
398code to ensure that memory accesses and array indexing operations are safe, and
399instruments the code with run-time checks when safety cannot be proven
400statically.
401</p>
402</div>
403
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]404<!--=========================================================================-->
405<div class="doc_subsection">
406<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
407</div>
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]408
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]409<div class="doc_text">
410<p>
411<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
412harness to build OpenJDK using only free software build tools and to provide
413replacements for the not-yet free parts of OpenJDK. One of the extensions that
414IcedTea provides is a new JIT compiler named <a
415href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
416to provide native code generation without introducing processor-dependent
417code.
418</p>
419<p>Icedtea6 1.8 and later have been tested and are known to work with
420LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
421</p>
422</div>
423
424<!--=========================================================================-->
425<div class="doc_subsection">
426<a name="llvm-lua">LLVM-Lua</a>
427</div>
428
429<div class="doc_text">
430<p>
431<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
432 to add JIT and static compiling support to the Lua VM. Lua
433bytecode is analyzed to remove type checks, then LLVM is used to compile the
434bytecode down to machine code.
435</p>
436<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
437</p>
438</div>
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]439
440<!--=========================================================================-->
441<div class="doc_subsection">
442<a name="MacRuby">MacRuby</a>
443</div>
444
445<div class="doc_text">
446<p>
447<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on
448core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for
449optimization passes, JIT compilation and exception handling. It also allows
450static (ahead-of-time) compilation of Ruby code straight to machine code.
451</p>
452<p>The upcoming MacRuby 0.6 release works with LLVM 2.7.
453</p>
454</div>
455
Chris Lattner745cf9f2010-04-26 17:38:10 +0000[diff] [blame]456<!--=========================================================================-->
457<div class="doc_subsection">
458<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
459</div>
460
461<div class="doc_text">
462<p>
463<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
464state-of-the-art programming suite for Haskell, a standard lazy
465functional programming language. It includes an optimizing static
466compiler generating good code for a variety of platforms, together
467with an interactive system for convenient, quick development.</p>
468
469<p>In addition to the existing C and native code generators, GHC now
470supports an <a
471href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
472code generator</a>. GHC supports LLVM 2.7.</p>
473
474</div>
475
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]476
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]477<!-- *********************************************************************** -->
478<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]479 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]480</div>
481<!-- *********************************************************************** -->
482
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]483<div class="doc_text">
484
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]485<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]486minor improvements. Some of the major improvements and new features are listed
487in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]488</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]489
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]490</div>
491
492<!--=========================================================================-->
493<div class="doc_subsection">
494<a name="orgchanges">LLVM Community Changes</a>
495</div>
496
497<div class="doc_text">
498
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]499<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
500organization changes have happened:
501</p>
502
503<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]504<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]505
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]506<li>Ted Kremenek and Doug Gregor have stepped forward as <a
507 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]508 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]509
510<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
511 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
512 to learn about new LLVM-related features as they are implemented. Several
513 features in this release are already explained on the blog.</li>
514
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]515<li>The LLVM web pages are now checked into the SVN server, in the "www",
516 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]517 largely inaccessible old CVS server.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]518
519<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
520 faster) server. It is still graciously hosted at the University of Illinois
521 of Urbana Champaign.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]522</ul>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]523</div>
524
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]525<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]526<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]527<a name="majorfeatures">Major New Features</a>
528</div>
529
530<div class="doc_text">
531
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]532<p>LLVM 2.7 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]533
534<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]535<li>2.7 includes initial support for the <a
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]536 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
537 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]538
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]539<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]540 supports many different use cases, including allowing front-end authors to
541 encode source level information into LLVM IR, which is consumed by later
542 language-specific passes. This is a great way to do high-level optimizations
543 like devirtualization, type-based alias analysis, etc. See the <a
544 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
545 Extensible Metadata Blog Post</a> for more information.</li>
546
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]547<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]548in a completely new way, built on extensible metadata. The new implementation
549is much more memory efficient and paves the way for improvements to optimized
550code debugging experience.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]551
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]552<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]553 indirect branch through a pointer. This is particularly useful for
554 interpreter loops, and is used to implement the GCC "address of label"
555 extension. For more information, see the <a
556href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
557Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]558
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]559<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]560 disassembling target machine code. These APIs are useful for a variety of
561 low level clients, and are surfaced in the new "enhanced disassembly" API.
562 For more information see the <a
563 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
564 Disassembler Blog Post</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]565
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]566<li>2.7 includes major parts of the work required by the new MC Project,
567 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]568
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]569</ul>
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]570
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]571</div>
572
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]573<!--=========================================================================-->
574<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]575<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]576</div>
577
578<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]579<p>LLVM IR has several new features for better support of new targets and that
580expose new optimization opportunities:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]581
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]582<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]583<li>LLVM IR now supports a 16-bit "half float" data type through <a
584 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
585<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]586 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]587 optimizer that a function was declared 'inline' and thus the inliner should
588 weight it higher when considering inlining it. The later
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]589 indicates to the code generator that the function diverges from the platform
590 ABI on stack alignment.</li>
591<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
592 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]593 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]594 extension.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]595<li>LLVM IR now supports marking load and store instructions with <a
596 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
597 metadata feature). This hint encourages the code
598 generator to generate non-temporal accesses when possible, which are useful
599 for code that is carefully managing cache behavior. Currently, only the
600 X86 backend provides target support for this feature.</li>
601
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]602<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifdd39cd12010-04-22 10:11:24 +0000[diff] [blame]603 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]604 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]605 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]606
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]607</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]608
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]609</div>
610
611<!--=========================================================================-->
612<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]613<a name="optimizer">Optimizer Improvements</a>
614</div>
615
616<div class="doc_text">
617
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]618<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]619release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]620
621<ul>
622
Chris Lattnerbf1bb302010-04-27 07:28:11 +0000[diff] [blame]623<li>The inliner now merges arrays stack objects in different callees when
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]624 inlining multiple call sites into one function. This reduces the stack size
625 of the resultant function.</li>
626<li>The -basicaa alias analysis pass (which is the default) has been improved to
627 be less dependent on "type safe" pointers. It can now look through bitcasts
628 and other constructs more aggressively, allowing better load/store
629 optimization.</li>
630<li>The load elimination optimization in the GVN Pass [<a
631href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
632 blog post</a>] has been substantially improved to be more aggressive about
633 partial redundancy elimination and do more aggressive phi translation. Please
634 see the <a
635 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
636 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
637 Blog Post</a> for more details.</li>
638<li>The module <a href="LangRef.html#datalayout">target data string</a> now
Wesley Peck63c86992010-04-22 13:28:34 +0000[diff] [blame]639 includes a notion of 'native' integer data types for the target. This
640 helps mid-level optimizations avoid promoting complex sequences of
641 operations to data types that are not natively supported (e.g. converting
642 i32 operations to i64 on 32-bit chips).</li>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]643<li>The mid-level optimizer is now conservative when operating on a module with
644 no target data. Previously, it would default to SparcV9 settings, which is
645 not what most people expected.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]646<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]647 conditionals and threading blocks with otherwise complex logic. It has
648 subsumed the old "Conditional Propagation" pass, and -condprop has been
649 removed from LLVM 2.7.</li>
650<li>The -instcombine pass has been refactored from being one huge file to being
651 a library of its own. Internally, it uses a customized IRBuilder to clean
652 it up and simplify it.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]653
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]654<li>The optimal edge profiling pass is reliable and much more complete than in
655 2.6. It can be used with the llvm-prof tool but isn't wired up to the
656 llvm-gcc and clang command line options yet.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]657
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]658<li>A new experimental alias analysis implementation, -scev-aa, has been added.
659 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
660 pointer offset expressions to disambiguate pointers. It can catch a few
661 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]662
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]663<li>The default pass ordering has been tweaked for improved optimization
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]664 effectiveness.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]665
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]666</ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]667
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]668</div>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]669
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]670
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]671<!--=========================================================================-->
672<div class="doc_subsection">
673<a name="executionengine">Interpreter and JIT Improvements</a>
674</div>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]675
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]676<div class="doc_text">
677
678<ul>
Wesley Peck0d7f61e2010-04-22 13:36:27 +0000[diff] [blame]679<li>The JIT now supports generating debug information and is compatible with
680the new GDB 7.0 (and later) interfaces for registering dynamically generated
681debug info.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]682
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]683<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin40715142010-01-29 19:10:38 +0000[diff] [blame]684to compiling eagerly</a> to avoid a race condition in the lazy JIT.
685Clients that still want the lazy JIT can switch it on by calling
686<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]687
Jeffrey Yasskinc0577082010-02-11 01:07:39 +0000[diff] [blame]688<li>It is now possible to create more than one JIT instance in the same process.
689These JITs can generate machine code in parallel,
690although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
691still have to obey the other threading restrictions</a>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]692
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]693</ul>
694
695</div>
696
697<!--=========================================================================-->
698<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]699<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]700</div>
701
702<div class="doc_text">
703
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]704<p>We have put a significant amount of work into the code generator
705infrastructure, which allows us to implement more aggressive algorithms and make
706it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]707
708<ul>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]709<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
710 to emit many useful comments to .s files indicating information about spill
711 slots and loop nest structure. This should make it much easier to read and
712 understand assembly files. This is wired up in llvm-gcc and clang to
713 the <tt>-fverbose-asm</tt> option.</li>
714
Dan Gohman93087ff2010-04-22 20:50:43 +0000[diff] [blame]715<li>New LSR with "full strength reduction" mode, which can reduce address
716 register pressure in loops where address generation is important.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]717
718<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
719 is available and enabled by default. It catches redundancies exposed by
720 lowering.</li>
721<li>A new pre-register-allocation tail duplication pass is available and enabled
722 by default, it can substantially improve branch prediction quality in some
723 cases.</li>
724<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
725 is available and enabled by default. This pass can takes advantage
726 architecture features like x86-64 implicit zero extension behavior and
727 sub-registers.</li>
728<li>The code generator now supports a mode where it attempts to preserve the
729 order of instructions in the input code. This is important for source that
730 is hand scheduled and extremely sensitive to scheduling. It is compatible
731 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
732<li>The target-independent code generator now supports generating code with
733 arbitrary numbers of result values. Returning more values than was
734 previously supported is handled by returning through a hidden pointer. In
735 2.7, only the X86 and XCore targets have adopted support for this
736 though.</li>
737<li>The code generator now supports generating code that follows the
738 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
739 Convention</a> and ABI.</li>
740<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
741 selection</a>" phase of the code generator has been largely rewritten for
742 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
743 linked into the target to do the pattern matching, now it emits a much
744 smaller table which is read by the target-independent code. The primary
745 advantages of this approach is that the size and compile time of various
746 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
747 for example.</li>
748<li>Almost the entire code generator has switched to emitting code through the
749 MC interfaces instead of printing textually to the .s file. This led to a
750 number of cleanups and speedups. In 2.7, debug an exception handling
751 information does not go through MC yet.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]752</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]753</div>
754
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]755<!--=========================================================================-->
756<div class="doc_subsection">
757<a name="x86">X86-32 and X86-64 Target Improvements</a>
758</div>
759
760<div class="doc_text">
761<p>New features of the X86 target include:
762</p>
763
764<ul>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]765<li>The X86 backend now optimizes tails calls much more aggressively for
766 functions that use the standard C calling convention.</li>
767<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
768 registers, making the code generator more aggressive in cases where scalars
769 and vector types are mixed.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]770
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]771</ul>
772
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]773</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]774
775<!--=========================================================================-->
776<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]777<a name="ARM">ARM Target Improvements</a>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]778</div>
779
780<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]781<p>New features of the ARM target include:
782</p>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]783
784<ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]785
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]786<li>The ARM backend now generates instructions in unified assembly syntax.</li>
787
788<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
789 support differs slightly from the GCC implementation. Please see the
790 <a
791href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
792 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
793 helpful information if migrating code from GCC to LLVM-GCC.</li>
794
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]795<li>The ARM and Thumb code generators now use register scavenging for stack
Jim Grosbachc5595772010-04-22 18:28:43 +0000[diff] [blame]796 object address materialization. This allows the use of R3 as a general
797 purpose register in Thumb1 code, as it was previous reserved for use in
798 stack address materialization. Secondly, sequential uses of the same
799 value will now re-use the materialized constant.</li>
800
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]801<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]802 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
803 newer chips.</li>
Jim Grosbach95254a42010-04-22 18:33:31 +0000[diff] [blame]804
805<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize,
806 __sync_fetch_and_add, etc.).</li>
807
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]808</ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]809
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]810
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]811</div>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]812
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]813<!--=========================================================================-->
814<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]815<a name="newapis">New Useful APIs</a>
816</div>
817
818<div class="doc_text">
819
820<p>This release includes a number of new APIs that are used internally, which
821 may also be useful for external clients.
822</p>
823
824<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]825<li>The optimizer uses the new CodeMetrics class to measure the size of code.
Chris Lattner9d966ed2010-04-22 17:39:38 +0000[diff] [blame]826 Various passes (like the inliner, loop unswitcher, etc) all use this to make
827 more accurate estimates of the code size impact of various
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]828 optimizations.</li>
829<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]830 llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]831 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
832 without requiring the instruction to exist. This centralizes a lot of
833 ad-hoc symbolic manipulation code scattered in various passes.</li>
834<li>The optimizer now uses a new <a
835 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
836 class which efficiently supports
837 doing unstructured SSA update operations. This centralized a bunch of code
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]838 scattered throughout various passes (e.g. jump threading, lcssa,
839 loop rotate, etc) for doing this sort of thing. The code generator has a
840 similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]841 MachineSSAUpdater</a> class.</li>
842<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
843 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]844 expression API. Building on this, the <a
845 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
846 regular exressions.</li>
847<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
848 By default, this stream works the same way as "errs()", but if you pass
849 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
850 fixed sized circular buffer and the output is printed at the end of the
851 program's execution. This is helpful if you have a long lived compiler
852 process and you're interested in seeing snapshots in time.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]853</ul>
854
855
856</div>
857
858<!--=========================================================================-->
859<div class="doc_subsection">
860<a name="otherimprovements">Other Improvements and New Features</a>
861</div>
862
863<div class="doc_text">
864<p>Other miscellaneous features include:</p>
865
866<ul>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]867<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
868 get this, configure LLVM with the --enable-shared option.</li>
869
Wesley Pecka85292d2010-04-22 13:53:54 +0000[diff] [blame]870<li>LLVM command line tools now overwrite their output by default. Previously,
871 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]872 behave more like standard unix tools.</li>
873
874<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
875 file, and automatically do the right thing. This means you don't need to
876 explicitly use the llvm-as tool for most things.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]877</ul>
878
879</div>
880
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]881
882<!--=========================================================================-->
883<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]884<a name="changes">Major Changes and Removed Features</a>
885</div>
886
887<div class="doc_text">
888
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]889<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]890on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]891from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]892
893<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]894
895<li>
896The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
897("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
898profiling ("rsprofiling") passes have all been removed. They were not being
899actively maintained and had substantial problems. If you are interested in
900these components, you are welcome to ressurect them from SVN, fix the
901correctness problems, and resubmit them to mainline.</li>
902
903<li>LLVM now defaults to building most libraries with RTTI turned off, providing
904a code size reduction. Packagers who are interested in building LLVM to support
905plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
906and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
907document.</li>
908
Jeffrey Yasskin260af332010-02-09 23:03:44 +0000[diff] [blame]909<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
910if you have it installed. This makes it more likely that an LLVM built on one
911system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]912configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]913
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]914<li>Debug information uses a completely different representation, an LLVM 2.6
915.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
916
917<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
918 along with LowerAllocations pass. Now you should just use a call to the
919 malloc and free functions in libc. These calls are optimized as well as
920 the old instructions were.</li>
921</ul>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]922
923<p>In addition, many APIs have changed in this release. Some of the major LLVM
924API changes are:</p>
925
926<ul>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]927
Dan Gohman5577c602010-05-03 23:51:05 +0000[diff] [blame]928<li>The <tt>add</tt>, <tt>sub</tt>, and <tt>mul</tt> instructions no longer
929support floating-point operands. The <tt>fadd</tt>, <tt>fsub</tt>, and
930<tt>fmul</tt> instructions should be used for this purpose instead.</li>
Daniel Dunbar61f41422010-02-10 04:09:52 +0000[diff] [blame]931
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]932</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]933
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]934</div>
935
936
937
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]938<!-- *********************************************************************** -->
939<div class="doc_section">
940 <a name="portability">Portability and Supported Platforms</a>
941</div>
942<!-- *********************************************************************** -->
943
944<div class="doc_text">
945
946<p>LLVM is known to work on the following platforms:</p>
947
948<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]949<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]950 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
951 systems).</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]952<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]953 and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]954<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]955<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
956 support is available for native builds with Visual C++).</li>
Chris Lattner9235ce52009-10-16 16:30:58 +0000[diff] [blame]957<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]958<li>Alpha-based machines running Debian GNU/Linux.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]959</ul>
960
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]961<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]962to the machine and operating system on which it is built. However, minor
963porting may be required to get LLVM to work on new platforms. We welcome your
964portability patches and reports of successful builds or error messages.</p>
965
966</div>
967
968<!-- *********************************************************************** -->
969<div class="doc_section">
970 <a name="knownproblems">Known Problems</a>
971</div>
972<!-- *********************************************************************** -->
973
974<div class="doc_text">
975
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]976<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]977listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]978href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
979there isn't already one.</p>
980
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]981<ul>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]982<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
983using the stock GCC 3.x.x series 'out the box',
Chris Lattnerc09ffd22009-11-03 21:50:09 +0000[diff] [blame]984See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]985However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
986for x86/x86-64 has been made available from the third party AuroraUX Project
987that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
988</ul>
989
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]990</div>
991
992<!-- ======================================================================= -->
993<div class="doc_subsection">
994 <a name="experimental">Experimental features included with this release</a>
995</div>
996
997<div class="doc_text">
998
999<p>The following components of this LLVM release are either untested, known to
1000be broken or unreliable, or are in early development. These components should
1001not be relied on, and bugs should not be filed against them, but they may be
1002useful 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]1003components, please contact us on the <a
1004href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1005
1006<ul>
Wesley Peckbe6dc822010-03-18 14:31:30 +0000[diff] [blame]1007<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
1008 backends are experimental.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1009<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1010 supported value for this option. The MachO writer is experimental, and
1011 works much better in mainline SVN.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1012</ul>
1013
1014</div>
1015
1016<!-- ======================================================================= -->
1017<div class="doc_subsection">
1018 <a name="x86-be">Known problems with the X86 back-end</a>
1019</div>
1020
1021<div class="doc_text">
1022
1023<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]1024 <li>The X86 backend does not yet support
1025 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1026 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1027 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1028 <li>The X86 backend generates inefficient floating point code when configured
1029 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]1030 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1031 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1032 runtime currently due to lack of support for the 'u' inline assembly
1033 constraint and for X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1034 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1035 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1036 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1037</ul>
1038
1039</div>
1040
1041<!-- ======================================================================= -->
1042<div class="doc_subsection">
1043 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1044</div>
1045
1046<div class="doc_text">
1047
1048<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1049<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1050compilation, and lacks support for debug information.</li>
1051</ul>
1052
1053</div>
1054
1055<!-- ======================================================================= -->
1056<div class="doc_subsection">
1057 <a name="arm-be">Known problems with the ARM back-end</a>
1058</div>
1059
1060<div class="doc_text">
1061
1062<ul>
1063<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]1064processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1065results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1066<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1067</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1068</ul>
1069
1070</div>
1071
1072<!-- ======================================================================= -->
1073<div class="doc_subsection">
1074 <a name="sparc-be">Known problems with the SPARC back-end</a>
1075</div>
1076
1077<div class="doc_text">
1078
1079<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1080<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]1081 support the 64-bit SPARC ABI (-m64).</li>
1082</ul>
1083
1084</div>
1085
1086<!-- ======================================================================= -->
1087<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1088 <a name="mips-be">Known problems with the MIPS back-end</a>
1089</div>
1090
1091<div class="doc_text">
1092
1093<ul>
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1094<li>64-bit MIPS targets are not supported yet.</li>
1095</ul>
1096
1097</div>
1098
1099<!-- ======================================================================= -->
1100<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1101 <a name="alpha-be">Known problems with the Alpha back-end</a>
1102</div>
1103
1104<div class="doc_text">
1105
1106<ul>
1107
1108<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1109appropriate nops inserted to ensure restartability.</li>
1110
1111</ul>
1112</div>
1113
1114<!-- ======================================================================= -->
1115<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1116 <a name="c-be">Known problems with the C back-end</a>
1117</div>
1118
1119<div class="doc_text">
1120
1121<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1122<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1123 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]1124<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1125 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]1126 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]1127<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]1128<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1129</ul>
1130
1131</div>
1132
1133
1134<!-- ======================================================================= -->
1135<div class="doc_subsection">
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1136 <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]1137</div>
1138
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1139<div class="doc_text">
1140
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1141<p>The only major language feature of GCC not supported by llvm-gcc is
1142 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1143 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1144 supported on some targets (these are used when you take the address of a
1145 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1146
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1147</div>
1148
1149<!-- ======================================================================= -->
1150<div class="doc_subsection">
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1151 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1152</div>
1153
1154<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1155<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1156<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1157 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1158 tools/gfortran component for details.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1159</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1160</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1161
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1162<!-- ======================================================================= -->
1163<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1164 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1165</div>
1166
1167<div class="doc_text">
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1168The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1169technology, and problems should be expected.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1170<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1171<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]1172to lack of trampoline support (pointers to nested functions) on other platforms.
1173However, 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]1174which does support trampolines.</li>
1175<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]1176This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1177exception handling, which is used internally by the compiler.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1178Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]1179<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1180and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]1181(c380004 also fails with gcc-4.2 mainline).
1182If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1183causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsc2a29a02009-03-02 16:35:57 +0000[diff] [blame]1184<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1185<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1186<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]1187crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1188<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1189or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1190or use representation clauses that result in a field of a non-discrete type
1191starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1192<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1193'main' as generated by the Ada binder to be invalid</a>.
1194Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1195<tt>envp</tt> rather than integers.</li>
1196<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1197ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1198</ul>
1199</div>
1200
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1201<!-- *********************************************************************** -->
1202<div class="doc_section">
1203 <a name="additionalinfo">Additional Information</a>
1204</div>
1205<!-- *********************************************************************** -->
1206
1207<div class="doc_text">
1208
1209<p>A wide variety of additional information is available on the <a
1210href="http://llvm.org">LLVM web page</a>, in particular in the <a
1211href="http://llvm.org/docs/">documentation</a> section. The web page also
1212contains versions of the API documentation which is up-to-date with the
1213Subversion version of the source code.
1214You can access versions of these documents specific to this release by going
1215into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1216
1217<p>If you have any questions or comments about LLVM, please feel free to contact
1218us via the <a href="http://llvm.org/docs/#maillist"> mailing
1219lists</a>.</p>
1220
1221</div>
1222
1223<!-- *********************************************************************** -->
1224
1225<hr>
1226<address>
1227 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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