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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 67bf37f4be7fe0dc24a4059aeb105de50d73893a / . / 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.
86 llvm devmtg
87 compiler_rt
88 KLEE web page at klee.llvm.org
89 Many new papers added to /pubs/
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]90 Mention gcc plugin.
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]91 -->
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]92
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]93<!-- *********************************************************************** -->
94<div class="doc_section">
95 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]96</div>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]97<!-- *********************************************************************** -->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]98
99<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]100<p>
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]101The LLVM 2.7 distribution currently consists of code from the core LLVM
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]102repository (which roughly includes the LLVM optimizers, code generators
103and supporting tools), the Clang repository and the llvm-gcc repository. In
104addition to this code, the LLVM Project includes other sub-projects that are in
105development. Here we include updates on these subprojects.
Bill Wendlingdde41b82009-03-02 04:28:57 +0000[diff] [blame]106</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]107
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]108</div>
109
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]110
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]111<!--=========================================================================-->
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]112<div class="doc_subsection">
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]113<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]114</div>
115
116<div class="doc_text">
117
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]118<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
119C++, and Objective-C languages. Clang aims to provide a better user experience
120through expressive diagnostics, a high level of conformance to language
121standards, fast compilation, and low memory use. Like LLVM, Clang provides a
122modular, library-based architecture that makes it suitable for creating or
123integrating with other development tools. Clang is considered a
124production-quality compiler for C and Objective-C on x86 (32- and 64-bit).</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]125
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]126<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]127
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]128<ul>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]129
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]130<li>C++ Support: Clang is now capable of self-hosting! While still
131alpha-quality, Clang's C++ support has matured enough to build LLVM and Clang,
132and C++ is now enabled by default. See the <a
133href="http://clang.llvm.org/cxx_compatibility.html">Clang C++ compatibility
134page</a> for common C++ migration issues.</li>
Douglas Gregor3235b4f2010-04-22 20:42:40 +0000[diff] [blame]135
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]136<li>Objective-C: Clang now includes experimental support for an updated
137Objective-C ABI on non-Darwin platforms. This includes support for non-fragile
138instance variables and accelerated proxies, as well as greater potential for
139future optimisations. The new ABI is used when compiling with the
140-fobjc-nonfragile-abi and -fgnu-runtime options. Code compiled with these
141options may be mixed with code compiled with GCC or clang using the old GNU ABI,
142but requires the libobjc2 runtime from the GNUstep project.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]143
Chris Lattnerefdea452010-04-26 17:42:18 +0000[diff] [blame]144<li>New warnings: Clang contains a number of new warnings, including
145control-flow warnings (unreachable code, missing return statements in a
146non-<code>void</code> function, etc.), sign-comparison warnings, and improved
147format-string warnings.</li>
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]148
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]149<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]150CIndex library. Although we may make some changes to the API in the future, it
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]151is intended to be stable and has been designed for use by external projects. See
152the Clang
153doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
Wesley Peck43e93692010-04-22 14:19:00 +0000[diff] [blame]154documentation for more details. The CIndex API also includes a preliminary
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]155set of Python bindings.</li>
156
157<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
158ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
Gabor Greif8abc1962010-04-25 21:27:54 +0000[diff] [blame]159suitable for use as a beta quality ARM compiler.</li>
David Chisnall25635df2010-04-25 19:13:33 +0000[diff] [blame]160
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]161</ul>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]162</div>
163
164<!--=========================================================================-->
165<div class="doc_subsection">
166<a name="clangsa">Clang Static Analyzer</a>
167</div>
168
169<div class="doc_text">
170
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]171<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
172 project is an effort to use static source code analysis techniques to
173 automatically find bugs in C and Objective-C programs (and hopefully <a
174 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
175 future</a>!). The tool is very good at finding bugs that occur on specific
176 paths through code, such as on error conditions.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]177
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]178<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
179 minor improvements, including better support for tracking the fields of
180 structures, initial support (not enabled by default yet) for doing
181 interprocedural (cross-function) analysis, and new checks have been added.
182</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]183
184</div>
185
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]186<!--=========================================================================-->
187<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]188<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]189</div>
190
191<div class="doc_text">
192<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]193The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]194a JVM and a CLI Virtual Machine (Microsoft .NET is an
195implementation of the CLI) using LLVM for static and just-in-time
196compilation.</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]197
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]198<p>
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]199With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
200virtual machines. VMKit now offers precise and efficient garbage collection with
201multi-threading support, thanks to the MMTk memory management toolkit, as well
202as just in time and ahead of time compilation with LLVM. The major changes in
203VMKit 0.27 are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]204
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]205<ul>
206
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]207<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
208 The first collector to be ported is the MarkSweep collector, which is precise,
209 and drastically improves the performance of VMKit.</li>
210<li>Line number information in the JVM: by using the debug metadata of LLVM, the
211 JVM now supports precise line number information, useful when printing a stack
212 trace.</li>
213<li>Interface calls in the JVM: we implemented a variant of the Interface Method
214 Table technique for interface calls in the JVM.
215</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]216
217</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]218</div>
219
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]220
221<!--=========================================================================-->
222<div class="doc_subsection">
223<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
224</div>
225
226<div class="doc_text">
227<p>
228The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
229is a simple library that provides an implementation of the low-level
230target-specific hooks required by code generation and other runtime components.
231For example, when compiling for a 32-bit target, converting a double to a 64-bit
232unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
233function. The compiler-rt library provides highly optimized implementations of
234this and other low-level routines (some are 3x faster than the equivalent
235libgcc routines).</p>
236
237<p>
238All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]239License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
240supports ARM targets.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]241
242</div>
243
244<!--=========================================================================-->
245<div class="doc_subsection">
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]246<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]247</div>
248
249<div class="doc_text">
250<p>
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]251<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
252gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
253gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
254whatsoever (currently one small patch is needed). This is thanks to the new
255<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
256makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
257which is nothing more than a dynamic library which conforms to the gcc plugin
258interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
259instead of the gcc optimizers, and the LLVM code generators instead of the gcc
260code generators, just like llvm-gcc. To use it, you add
261"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
262becomes llvm-gcc-4.5!
263</p>
264
265<p>
266DragonEgg is still a work in progress. Currently C works very well, while C++,
267Ada and Fortran work fairly well. All other languages either don't work at all,
268or 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]269supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]270</p>
271
272<p>
Duncan Sandsa9cc3892010-04-21 13:51:48 +0000[diff] [blame]273DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]274</p>
275
276</div>
277
278
279<!--=========================================================================-->
280<div class="doc_subsection">
281<a name="mc">llvm-mc: Machine Code Toolkit</a>
282</div>
283
284<div class="doc_text">
285<p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]286The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
287of problems in the realm of assembly, disassembly, object file format handling,
288and a number of other related areas that CPU instruction-set level tools work
289in. It is a sub-project of LLVM which provides it with a number of advantages
290over other compilers that do not have tightly integrated assembly-level tools.
291For a gentle introduction, please see the <a
292href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
293LLVM MC Project Blog Post</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]294</p>
295
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]296<p>2.7 includes major parts of the work required by the new MC Project. A few
297 targets have been refactored to support it, and work is underway to support a
Gabor Greif9e25ea72010-04-25 21:30:22 +0000[diff] [blame]298 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]299 made substantially more progress on LLVM mainline.</p>
300
301<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]302 X86 .s file into intel syntax. You can do this with something like:</p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]303<pre>
304 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
305</pre>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]306
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]307</div>
308
309
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]310<!-- *********************************************************************** -->
311<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]312 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]313</div>
314<!-- *********************************************************************** -->
315
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]316<div class="doc_text">
317
318<p>An exciting aspect of LLVM is that it is used as an enabling technology for
319 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]320 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]321</div>
322
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]323<!--=========================================================================-->
324<div class="doc_subsection">
325<a name="pure">Pure</a>
326</div>
327
328<div class="doc_text">
329<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]330<a href="http://pure-lang.googlecode.com/">Pure</a>
331is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]332Programs are collections of equations which are used to evaluate expressions in
333a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]334lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]335built-in list and matrix support (including list and matrix comprehensions) and
336an easy-to-use C interface. The interpreter uses LLVM as a backend to
337 JIT-compile Pure programs to fast native code.</p>
338
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]339<p>Pure versions 0.43 and later have been tested and are known to work with
340LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
341
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]342</div>
343
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]344<!--=========================================================================-->
345<div class="doc_subsection">
346<a name="RoadsendPHP">Roadsend PHP</a>
347</div>
348
349<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]350<p>
351<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattner9e08de12009-03-02 19:07:24 +0000[diff] [blame]352source implementation of the PHP programming
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]353language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]354reimplementation of an earlier project that is now based on LLVM.
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]355</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]356</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]357
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]358<!--=========================================================================-->
359<div class="doc_subsection">
360<a name="UnladenSwallow">Unladen Swallow</a>
361</div>
362
363<div class="doc_text">
364<p>
365<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
366branch of <a href="http://python.org/">Python</a> intended to be fully
367compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerd7db82c2010-03-18 06:52:15 +0000[diff] [blame]368compiler.
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]369</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]370</div>
371
372<!--=========================================================================-->
373<div class="doc_subsection">
Chris Lattner49894862010-03-29 17:50:39 +0000[diff] [blame]374<a name="tce">TTA-based Codesign Environment (TCE)</a>
375</div>
376
377<div class="doc_text">
378<p>
379<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
380application-specific processors (ASP) based on the Transport triggered
381architecture (TTA). The toolset provides a complete co-design flow from C/C++
382programs down to synthesizable VHDL and parallel program binaries. Processor
383customization points include the register files, function units, supported
384operations, and the interconnection network.</p>
385
386<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
387independent optimizations and also for parts of code generation. It generates
388new LLVM-based code generators "on the fly" for the designed TTA processors and
389loads them in to the compiler backend as runtime libraries to avoid per-target
390recompilation of larger parts of the compiler chain.</p>
391
392</div>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]393
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]394<!--=========================================================================-->
395<div class="doc_subsection">
396<a name="safecode">SAFECode Compiler</a>
397</div>
398
399<div class="doc_text">
400<p>
401<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
402compiler built using LLVM. It takes standard, unannotated C code, analyzes the
403code to ensure that memory accesses and array indexing operations are safe, and
404instruments the code with run-time checks when safety cannot be proven
405statically.
406</p>
407</div>
408
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]409<!--=========================================================================-->
410<div class="doc_subsection">
411<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
412</div>
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]413
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]414<div class="doc_text">
415<p>
416<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
417harness to build OpenJDK using only free software build tools and to provide
418replacements for the not-yet free parts of OpenJDK. One of the extensions that
419IcedTea provides is a new JIT compiler named <a
420href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
421to provide native code generation without introducing processor-dependent
422code.
423</p>
424<p>Icedtea6 1.8 and later have been tested and are known to work with
425LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
426</p>
427</div>
428
429<!--=========================================================================-->
430<div class="doc_subsection">
431<a name="llvm-lua">LLVM-Lua</a>
432</div>
433
434<div class="doc_text">
435<p>
436<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
437 to add JIT and static compiling support to the Lua VM. Lua
438bytecode is analyzed to remove type checks, then LLVM is used to compile the
439bytecode down to machine code.
440</p>
441<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
442</p>
443</div>
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]444
445<!--=========================================================================-->
446<div class="doc_subsection">
447<a name="MacRuby">MacRuby</a>
448</div>
449
450<div class="doc_text">
451<p>
452<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby based on
453core Mac OS technologies, sponsored by Apple Inc. It uses LLVM at runtime for
454optimization passes, JIT compilation and exception handling. It also allows
455static (ahead-of-time) compilation of Ruby code straight to machine code.
456</p>
457<p>The upcoming MacRuby 0.6 release works with LLVM 2.7.
458</p>
459</div>
460
Chris Lattner745cf9f2010-04-26 17:38:10 +0000[diff] [blame]461<!--=========================================================================-->
462<div class="doc_subsection">
463<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
464</div>
465
466<div class="doc_text">
467<p>
468<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
469state-of-the-art programming suite for Haskell, a standard lazy
470functional programming language. It includes an optimizing static
471compiler generating good code for a variety of platforms, together
472with an interactive system for convenient, quick development.</p>
473
474<p>In addition to the existing C and native code generators, GHC now
475supports an <a
476href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
477code generator</a>. GHC supports LLVM 2.7.</p>
478
479</div>
480
Chris Lattner7a12c992010-04-22 21:34:16 +0000[diff] [blame]481
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]482<!-- *********************************************************************** -->
483<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]484 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]485</div>
486<!-- *********************************************************************** -->
487
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]488<div class="doc_text">
489
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]490<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]491minor improvements. Some of the major improvements and new features are listed
492in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]493</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]494
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]495</div>
496
497<!--=========================================================================-->
498<div class="doc_subsection">
499<a name="orgchanges">LLVM Community Changes</a>
500</div>
501
502<div class="doc_text">
503
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]504<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
505organization changes have happened:
506</p>
507
508<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]509<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]510
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]511<li>Ted Kremenek and Doug Gregor have stepped forward as <a
512 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]513 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]514
515<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
516 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
517 to learn about new LLVM-related features as they are implemented. Several
518 features in this release are already explained on the blog.</li>
519
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]520<li>The LLVM web pages are now checked into the SVN server, in the "www",
521 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]522 largely inaccessible old CVS server.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]523
524<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
525 faster) server. It is still graciously hosted at the University of Illinois
526 of Urbana Champaign.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]527</ul>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]528</div>
529
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]530<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]531<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]532<a name="majorfeatures">Major New Features</a>
533</div>
534
535<div class="doc_text">
536
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]537<p>LLVM 2.7 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]538
539<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]540<li>2.7 includes initial support for the <a
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]541 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
542 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]543
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]544<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]545 supports many different use cases, including allowing front-end authors to
546 encode source level information into LLVM IR, which is consumed by later
547 language-specific passes. This is a great way to do high-level optimizations
548 like devirtualization, type-based alias analysis, etc. See the <a
549 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
550 Extensible Metadata Blog Post</a> for more information.</li>
551
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]552<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]553in a completely new way, built on extensible metadata. The new implementation
554is much more memory efficient and paves the way for improvements to optimized
555code debugging experience.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]556
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]557<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]558 indirect branch through a pointer. This is particularly useful for
559 interpreter loops, and is used to implement the GCC "address of label"
560 extension. For more information, see the <a
561href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
562Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]563
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]564<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]565 disassembling target machine code. These APIs are useful for a variety of
566 low level clients, and are surfaced in the new "enhanced disassembly" API.
567 For more information see the <a
568 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
569 Disassembler Blog Post</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]570
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]571<li>2.7 includes major parts of the work required by the new MC Project,
572 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]573
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]574</ul>
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]575
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]576</div>
577
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]578<!--=========================================================================-->
579<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]580<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]581</div>
582
583<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]584<p>LLVM IR has several new features for better support of new targets and that
585expose new optimization opportunities:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]586
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]587<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]588<li>LLVM IR now supports a 16-bit "half float" data type through <a
589 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
590<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]591 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]592 optimizer that a function was declared 'inline' and thus the inliner should
593 weight it higher when considering inlining it. The later
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]594 indicates to the code generator that the function diverges from the platform
595 ABI on stack alignment.</li>
596<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
597 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]598 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]599 extension.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]600<li>LLVM IR now supports marking load and store instructions with <a
601 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
602 metadata feature). This hint encourages the code
603 generator to generate non-temporal accesses when possible, which are useful
604 for code that is carefully managing cache behavior. Currently, only the
605 X86 backend provides target support for this feature.</li>
606
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]607<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifdd39cd12010-04-22 10:11:24 +0000[diff] [blame]608 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]609 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]610 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]611
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]612</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]613
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]614</div>
615
616<!--=========================================================================-->
617<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]618<a name="optimizer">Optimizer Improvements</a>
619</div>
620
621<div class="doc_text">
622
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]623<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]624release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]625
626<ul>
627
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]628<li>The inliner reuses now merges arrays stack objects in different callees when
629 inlining multiple call sites into one function. This reduces the stack size
630 of the resultant function.</li>
631<li>The -basicaa alias analysis pass (which is the default) has been improved to
632 be less dependent on "type safe" pointers. It can now look through bitcasts
633 and other constructs more aggressively, allowing better load/store
634 optimization.</li>
635<li>The load elimination optimization in the GVN Pass [<a
636href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
637 blog post</a>] has been substantially improved to be more aggressive about
638 partial redundancy elimination and do more aggressive phi translation. Please
639 see the <a
640 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
641 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
642 Blog Post</a> for more details.</li>
643<li>The module <a href="LangRef.html#datalayout">target data string</a> now
Wesley Peck63c86992010-04-22 13:28:34 +0000[diff] [blame]644 includes a notion of 'native' integer data types for the target. This
645 helps mid-level optimizations avoid promoting complex sequences of
646 operations to data types that are not natively supported (e.g. converting
647 i32 operations to i64 on 32-bit chips).</li>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]648<li>The mid-level optimizer is now conservative when operating on a module with
649 no target data. Previously, it would default to SparcV9 settings, which is
650 not what most people expected.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]651<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]652 conditionals and threading blocks with otherwise complex logic. It has
653 subsumed the old "Conditional Propagation" pass, and -condprop has been
654 removed from LLVM 2.7.</li>
655<li>The -instcombine pass has been refactored from being one huge file to being
656 a library of its own. Internally, it uses a customized IRBuilder to clean
657 it up and simplify it.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]658
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]659<li>The optimal edge profiling pass is reliable and much more complete than in
660 2.6. It can be used with the llvm-prof tool but isn't wired up to the
661 llvm-gcc and clang command line options yet.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]662
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]663<li>A new experimental alias analysis implementation, -scev-aa, has been added.
664 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
665 pointer offset expressions to disambiguate pointers. It can catch a few
666 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]667
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]668<li>The default pass ordering has been tweaked for improved optimization
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]669 effectiveness.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]670
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]671</ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]672
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]673</div>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]674
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]675
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]676<!--=========================================================================-->
677<div class="doc_subsection">
678<a name="executionengine">Interpreter and JIT Improvements</a>
679</div>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]680
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]681<div class="doc_text">
682
683<ul>
Wesley Peck0d7f61e2010-04-22 13:36:27 +0000[diff] [blame]684<li>The JIT now supports generating debug information and is compatible with
685the new GDB 7.0 (and later) interfaces for registering dynamically generated
686debug info.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]687
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]688<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin40715142010-01-29 19:10:38 +0000[diff] [blame]689to compiling eagerly</a> to avoid a race condition in the lazy JIT.
690Clients that still want the lazy JIT can switch it on by calling
691<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]692
Jeffrey Yasskinc0577082010-02-11 01:07:39 +0000[diff] [blame]693<li>It is now possible to create more than one JIT instance in the same process.
694These JITs can generate machine code in parallel,
695although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
696still have to obey the other threading restrictions</a>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]697
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]698</ul>
699
700</div>
701
702<!--=========================================================================-->
703<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]704<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]705</div>
706
707<div class="doc_text">
708
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]709<p>We have put a significant amount of work into the code generator
710infrastructure, which allows us to implement more aggressive algorithms and make
711it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]712
713<ul>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]714<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
715 to emit many useful comments to .s files indicating information about spill
716 slots and loop nest structure. This should make it much easier to read and
717 understand assembly files. This is wired up in llvm-gcc and clang to
718 the <tt>-fverbose-asm</tt> option.</li>
719
Dan Gohman93087ff2010-04-22 20:50:43 +0000[diff] [blame]720<li>New LSR with "full strength reduction" mode, which can reduce address
721 register pressure in loops where address generation is important.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]722
723<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
724 is available and enabled by default. It catches redundancies exposed by
725 lowering.</li>
726<li>A new pre-register-allocation tail duplication pass is available and enabled
727 by default, it can substantially improve branch prediction quality in some
728 cases.</li>
729<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
730 is available and enabled by default. This pass can takes advantage
731 architecture features like x86-64 implicit zero extension behavior and
732 sub-registers.</li>
733<li>The code generator now supports a mode where it attempts to preserve the
734 order of instructions in the input code. This is important for source that
735 is hand scheduled and extremely sensitive to scheduling. It is compatible
736 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
737<li>The target-independent code generator now supports generating code with
738 arbitrary numbers of result values. Returning more values than was
739 previously supported is handled by returning through a hidden pointer. In
740 2.7, only the X86 and XCore targets have adopted support for this
741 though.</li>
742<li>The code generator now supports generating code that follows the
743 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
744 Convention</a> and ABI.</li>
745<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
746 selection</a>" phase of the code generator has been largely rewritten for
747 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
748 linked into the target to do the pattern matching, now it emits a much
749 smaller table which is read by the target-independent code. The primary
750 advantages of this approach is that the size and compile time of various
751 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
752 for example.</li>
753<li>Almost the entire code generator has switched to emitting code through the
754 MC interfaces instead of printing textually to the .s file. This led to a
755 number of cleanups and speedups. In 2.7, debug an exception handling
756 information does not go through MC yet.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]757</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]758</div>
759
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]760<!--=========================================================================-->
761<div class="doc_subsection">
762<a name="x86">X86-32 and X86-64 Target Improvements</a>
763</div>
764
765<div class="doc_text">
766<p>New features of the X86 target include:
767</p>
768
769<ul>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]770<li>The X86 backend now optimizes tails calls much more aggressively for
771 functions that use the standard C calling convention.</li>
772<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
773 registers, making the code generator more aggressive in cases where scalars
774 and vector types are mixed.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]775
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]776</ul>
777
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]778</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]779
780<!--=========================================================================-->
781<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]782<a name="ARM">ARM Target Improvements</a>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]783</div>
784
785<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]786<p>New features of the ARM target include:
787</p>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]788
789<ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]790
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]791<li>The ARM backend now generates instructions in unified assembly syntax.</li>
792
793<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
794 support differs slightly from the GCC implementation. Please see the
795 <a
796href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
797 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
798 helpful information if migrating code from GCC to LLVM-GCC.</li>
799
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]800<li>The ARM and Thumb code generators now use register scavenging for stack
Jim Grosbachc5595772010-04-22 18:28:43 +0000[diff] [blame]801 object address materialization. This allows the use of R3 as a general
802 purpose register in Thumb1 code, as it was previous reserved for use in
803 stack address materialization. Secondly, sequential uses of the same
804 value will now re-use the materialized constant.</li>
805
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]806<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]807 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
808 newer chips.</li>
Jim Grosbach95254a42010-04-22 18:33:31 +0000[diff] [blame]809
810<li>Atomic builtins are now supported for ARMv6 and ARMv7 (__sync_synchronize,
811 __sync_fetch_and_add, etc.).</li>
812
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]813</ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]814
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]815
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]816</div>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]817
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]818<!--=========================================================================-->
819<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]820<a name="newapis">New Useful APIs</a>
821</div>
822
823<div class="doc_text">
824
825<p>This release includes a number of new APIs that are used internally, which
826 may also be useful for external clients.
827</p>
828
829<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]830<li>The optimizer uses the new CodeMetrics class to measure the size of code.
Chris Lattner9d966ed2010-04-22 17:39:38 +0000[diff] [blame]831 Various passes (like the inliner, loop unswitcher, etc) all use this to make
832 more accurate estimates of the code size impact of various
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]833 optimizations.</li>
834<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]835 llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]836 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
837 without requiring the instruction to exist. This centralizes a lot of
838 ad-hoc symbolic manipulation code scattered in various passes.</li>
839<li>The optimizer now uses a new <a
840 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
841 class which efficiently supports
842 doing unstructured SSA update operations. This centralized a bunch of code
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]843 scattered throughout various passes (e.g. jump threading, lcssa,
844 loop rotate, etc) for doing this sort of thing. The code generator has a
845 similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]846 MachineSSAUpdater</a> class.</li>
847<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
848 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]849 expression API. Building on this, the <a
850 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
851 regular exressions.</li>
852<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
853 By default, this stream works the same way as "errs()", but if you pass
854 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
855 fixed sized circular buffer and the output is printed at the end of the
856 program's execution. This is helpful if you have a long lived compiler
857 process and you're interested in seeing snapshots in time.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]858</ul>
859
860
861</div>
862
863<!--=========================================================================-->
864<div class="doc_subsection">
865<a name="otherimprovements">Other Improvements and New Features</a>
866</div>
867
868<div class="doc_text">
869<p>Other miscellaneous features include:</p>
870
871<ul>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]872<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
873 get this, configure LLVM with the --enable-shared option.</li>
874
Wesley Pecka85292d2010-04-22 13:53:54 +0000[diff] [blame]875<li>LLVM command line tools now overwrite their output by default. Previously,
876 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]877 behave more like standard unix tools.</li>
878
879<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
880 file, and automatically do the right thing. This means you don't need to
881 explicitly use the llvm-as tool for most things.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]882</ul>
883
884</div>
885
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]886
887<!--=========================================================================-->
888<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]889<a name="changes">Major Changes and Removed Features</a>
890</div>
891
892<div class="doc_text">
893
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]894<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]895on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]896from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]897
898<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]899
900<li>
901The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
902("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
903profiling ("rsprofiling") passes have all been removed. They were not being
904actively maintained and had substantial problems. If you are interested in
905these components, you are welcome to ressurect them from SVN, fix the
906correctness problems, and resubmit them to mainline.</li>
907
908<li>LLVM now defaults to building most libraries with RTTI turned off, providing
909a code size reduction. Packagers who are interested in building LLVM to support
910plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
911and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
912document.</li>
913
Jeffrey Yasskin260af332010-02-09 23:03:44 +0000[diff] [blame]914<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
915if you have it installed. This makes it more likely that an LLVM built on one
916system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]917configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]918
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]919<li>Debug information uses a completely different representation, an LLVM 2.6
920.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
921
922<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
923 along with LowerAllocations pass. Now you should just use a call to the
924 malloc and free functions in libc. These calls are optimized as well as
925 the old instructions were.</li>
926</ul>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]927
928<p>In addition, many APIs have changed in this release. Some of the major LLVM
929API changes are:</p>
930
931<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]932<li>Just about everything has been converted to use raw_ostream instead of
933 std::ostream.</li>
934<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
935 instead.</li>
936<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
937 instead.</li>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]938<li>The TargetAsmInfo interface was renamed to MCAsmInfo.</li>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]939<li><tt>ModuleProvider</tt> has been <a
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]940href="http://llvm.org/viewvc/llvm-project?view=rev&amp;revision=94686">removed</a>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]941and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
942Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
943replace <tt>getBitcodeModuleProvider</tt> with
944<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
945functions that used to accept <tt>ModuleProvider</tt>. Clients who
946wrote their own <tt>ModuleProvider</tt>s will need to derive from
947<tt>GVMaterializer</tt> instead and use
948<tt>Module::setMaterializer</tt> to attach it to a
949<tt>Module</tt>.</li>
950
951<li><tt>GhostLinkage</tt> has given up the ghost.
952<tt>GlobalValue</tt>s that have not yet been read from their backing
953storage have the same linkage they will have after being read in.
954Clients must replace calls to
955<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
956<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar61f41422010-02-10 04:09:52 +0000[diff] [blame]957
Duncan Sandsdd29fc82010-02-17 17:20:17 +0000[diff] [blame]958<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
959<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
960<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
961<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]962
963<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
964<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
965 booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
966<li>Some header files have been renamed:
967<ul>
968 <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
969 <tt>llvm/System/AIXDataTypesFix.h</tt></li>
970 <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
971 <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
972 <tt>llvm/Analysis/InlineCost.h</tt></li>
973 <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
974 <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
975</ul></li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]976</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]977
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]978</div>
979
980
981
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]982<!-- *********************************************************************** -->
983<div class="doc_section">
984 <a name="portability">Portability and Supported Platforms</a>
985</div>
986<!-- *********************************************************************** -->
987
988<div class="doc_text">
989
990<p>LLVM is known to work on the following platforms:</p>
991
992<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]993<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]994 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
995 systems).</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]996<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]997 and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]998<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]999<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
1000 support is available for native builds with Visual C++).</li>
Chris Lattner9235ce52009-10-16 16:30:58 +0000[diff] [blame]1001<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1002<li>Alpha-based machines running Debian GNU/Linux.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1003</ul>
1004
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]1005<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1006to the machine and operating system on which it is built. However, minor
1007porting may be required to get LLVM to work on new platforms. We welcome your
1008portability patches and reports of successful builds or error messages.</p>
1009
1010</div>
1011
1012<!-- *********************************************************************** -->
1013<div class="doc_section">
1014 <a name="knownproblems">Known Problems</a>
1015</div>
1016<!-- *********************************************************************** -->
1017
1018<div class="doc_text">
1019
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]1020<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]1021listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1022href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
1023there isn't already one.</p>
1024
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]1025<ul>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1026<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
1027using the stock GCC 3.x.x series 'out the box',
Chris Lattnerc09ffd22009-11-03 21:50:09 +0000[diff] [blame]1028See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1029However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
1030for x86/x86-64 has been made available from the third party AuroraUX Project
1031that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
1032</ul>
1033
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1034</div>
1035
1036<!-- ======================================================================= -->
1037<div class="doc_subsection">
1038 <a name="experimental">Experimental features included with this release</a>
1039</div>
1040
1041<div class="doc_text">
1042
1043<p>The following components of this LLVM release are either untested, known to
1044be broken or unreliable, or are in early development. These components should
1045not be relied on, and bugs should not be filed against them, but they may be
1046useful 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]1047components, please contact us on the <a
1048href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1049
1050<ul>
Wesley Peckbe6dc822010-03-18 14:31:30 +0000[diff] [blame]1051<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
1052 backends are experimental.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1053<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1054 supported value for this option. The MachO writer is experimental, and
1055 works much better in mainline SVN.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1056</ul>
1057
1058</div>
1059
1060<!-- ======================================================================= -->
1061<div class="doc_subsection">
1062 <a name="x86-be">Known problems with the X86 back-end</a>
1063</div>
1064
1065<div class="doc_text">
1066
1067<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]1068 <li>The X86 backend does not yet support
1069 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1070 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1071 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1072 <li>The X86 backend generates inefficient floating point code when configured
1073 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]1074 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1075 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1076 runtime currently due to lack of support for the 'u' inline assembly
1077 constraint and for X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1078 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1079 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1080 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1081</ul>
1082
1083</div>
1084
1085<!-- ======================================================================= -->
1086<div class="doc_subsection">
1087 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1088</div>
1089
1090<div class="doc_text">
1091
1092<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1093<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1094compilation, and lacks support for debug information.</li>
1095</ul>
1096
1097</div>
1098
1099<!-- ======================================================================= -->
1100<div class="doc_subsection">
1101 <a name="arm-be">Known problems with the ARM back-end</a>
1102</div>
1103
1104<div class="doc_text">
1105
1106<ul>
1107<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]1108processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1109results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1110<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1111</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1112</ul>
1113
1114</div>
1115
1116<!-- ======================================================================= -->
1117<div class="doc_subsection">
1118 <a name="sparc-be">Known problems with the SPARC back-end</a>
1119</div>
1120
1121<div class="doc_text">
1122
1123<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1124<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]1125 support the 64-bit SPARC ABI (-m64).</li>
1126</ul>
1127
1128</div>
1129
1130<!-- ======================================================================= -->
1131<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1132 <a name="mips-be">Known problems with the MIPS back-end</a>
1133</div>
1134
1135<div class="doc_text">
1136
1137<ul>
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1138<li>64-bit MIPS targets are not supported yet.</li>
1139</ul>
1140
1141</div>
1142
1143<!-- ======================================================================= -->
1144<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1145 <a name="alpha-be">Known problems with the Alpha back-end</a>
1146</div>
1147
1148<div class="doc_text">
1149
1150<ul>
1151
1152<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1153appropriate nops inserted to ensure restartability.</li>
1154
1155</ul>
1156</div>
1157
1158<!-- ======================================================================= -->
1159<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1160 <a name="c-be">Known problems with the C back-end</a>
1161</div>
1162
1163<div class="doc_text">
1164
1165<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1166<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1167 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]1168<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1169 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]1170 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]1171<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]1172<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1173</ul>
1174
1175</div>
1176
1177
1178<!-- ======================================================================= -->
1179<div class="doc_subsection">
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1180 <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]1181</div>
1182
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1183<div class="doc_text">
1184
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1185<p>The only major language feature of GCC not supported by llvm-gcc is
1186 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1187 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1188 supported on some targets (these are used when you take the address of a
1189 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1190
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1191</div>
1192
1193<!-- ======================================================================= -->
1194<div class="doc_subsection">
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1195 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1196</div>
1197
1198<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1199<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1200<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1201 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1202 tools/gfortran component for details.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1203</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1204</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1205
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1206<!-- ======================================================================= -->
1207<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1208 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1209</div>
1210
1211<div class="doc_text">
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1212The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1213technology, and problems should be expected.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1214<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1215<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]1216to lack of trampoline support (pointers to nested functions) on other platforms.
1217However, 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]1218which does support trampolines.</li>
1219<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]1220This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1221exception handling, which is used internally by the compiler.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1222Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]1223<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1224and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]1225(c380004 also fails with gcc-4.2 mainline).
1226If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1227causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsc2a29a02009-03-02 16:35:57 +0000[diff] [blame]1228<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1229<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1230<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]1231crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1232<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1233or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1234or use representation clauses that result in a field of a non-discrete type
1235starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1236<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1237'main' as generated by the Ada binder to be invalid</a>.
1238Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1239<tt>envp</tt> rather than integers.</li>
1240<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1241ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1242</ul>
1243</div>
1244
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1245<!-- *********************************************************************** -->
1246<div class="doc_section">
1247 <a name="additionalinfo">Additional Information</a>
1248</div>
1249<!-- *********************************************************************** -->
1250
1251<div class="doc_text">
1252
1253<p>A wide variety of additional information is available on the <a
1254href="http://llvm.org">LLVM web page</a>, in particular in the <a
1255href="http://llvm.org/docs/">documentation</a> section. The web page also
1256contains versions of the API documentation which is up-to-date with the
1257Subversion version of the source code.
1258You can access versions of these documents specific to this release by going
1259into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1260
1261<p>If you have any questions or comments about LLVM, please feel free to contact
1262us via the <a href="http://llvm.org/docs/#maillist"> mailing
1263lists</a>.</p>
1264
1265</div>
1266
1267<!-- *********************************************************************** -->
1268
1269<hr>
1270<address>
1271 <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]1273 <a href="http://validator.w3.org/check/referer"><img
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1275
1276 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
1277 Last modified: $Date$
1278</address>
1279
1280</body>
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