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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / bc647530491705d911c0ea2f35d9f67abdd3e162 / . / docs / ReleaseNotes.html
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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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
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]118<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]119
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]120<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]121
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]122<ul>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]123<li>FIXME: C++! Include a link to cxx_compatibility.html Clang 2.7 can
124bootstrap???</li>
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]125
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]126<li>CIndex API and Python bindings: Clang now includes a C API as part of the
127CIndex library. Although we make make some changes to the API in the future, it
128is intended to be stable and has been designed for use by external projects. See
129the Clang
130doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
Wesley Peck43e93692010-04-22 14:19:00 +0000[diff] [blame]131documentation for more details. The CIndex API also includes a preliminary
Daniel Dunbar29f1e722010-03-25 16:09:18 +0000[diff] [blame]132set of Python bindings.</li>
133
134<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
135ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
136suitable for use as a a beta quality ARM compiler.</li>
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]137</ul>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]138</div>
139
140<!--=========================================================================-->
141<div class="doc_subsection">
142<a name="clangsa">Clang Static Analyzer</a>
143</div>
144
145<div class="doc_text">
146
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]147<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
148 project is an effort to use static source code analysis techniques to
149 automatically find bugs in C and Objective-C programs (and hopefully <a
150 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
151 future</a>!). The tool is very good at finding bugs that occur on specific
152 paths through code, such as on error conditions.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]153
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]154<p>In the LLVM 2.7 time-frame, the analyzer core has made several major and
155 minor improvements, including better support for tracking the fields of
156 structures, initial support (not enabled by default yet) for doing
157 interprocedural (cross-function) analysis, and new checks have been added.
158</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]159
160</div>
161
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]162<!--=========================================================================-->
163<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]164<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]165</div>
166
167<div class="doc_text">
168<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]169The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]170a JVM and a CLI Virtual Machine (Microsoft .NET is an
171implementation of the CLI) using LLVM for static and just-in-time
172compilation.</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]173
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]174<p>
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]175With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
176virtual machines. VMKit now offers precise and efficient garbage collection with
177multi-threading support, thanks to the MMTk memory management toolkit, as well
178as just in time and ahead of time compilation with LLVM. The major changes in
179VMKit 0.27 are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]180
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]181<ul>
182
Chris Lattnerd5b62522010-03-29 18:34:13 +0000[diff] [blame]183<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
184 The first collector to be ported is the MarkSweep collector, which is precise,
185 and drastically improves the performance of VMKit.</li>
186<li>Line number information in the JVM: by using the debug metadata of LLVM, the
187 JVM now supports precise line number information, useful when printing a stack
188 trace.</li>
189<li>Interface calls in the JVM: we implemented a variant of the Interface Method
190 Table technique for interface calls in the JVM.
191</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]192
193</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]194</div>
195
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]196
197<!--=========================================================================-->
198<div class="doc_subsection">
199<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
200</div>
201
202<div class="doc_text">
203<p>
204The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
205is a simple library that provides an implementation of the low-level
206target-specific hooks required by code generation and other runtime components.
207For example, when compiling for a 32-bit target, converting a double to a 64-bit
208unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
209function. The compiler-rt library provides highly optimized implementations of
210this and other low-level routines (some are 3x faster than the equivalent
211libgcc routines).</p>
212
213<p>
214All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]215License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
216supports ARM targets.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]217
218</div>
219
220<!--=========================================================================-->
221<div class="doc_subsection">
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]222<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]223</div>
224
225<div class="doc_text">
226<p>
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]227<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
228gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
229gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
230whatsoever (currently one small patch is needed). This is thanks to the new
231<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
232makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
233which is nothing more than a dynamic library which conforms to the gcc plugin
234interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
235instead of the gcc optimizers, and the LLVM code generators instead of the gcc
236code generators, just like llvm-gcc. To use it, you add
237"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
238becomes llvm-gcc-4.5!
239</p>
240
241<p>
242DragonEgg is still a work in progress. Currently C works very well, while C++,
243Ada and Fortran work fairly well. All other languages either don't work at all,
244or 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]245supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands2d9c3082010-04-02 09:23:15 +0000[diff] [blame]246</p>
247
248<p>
Duncan Sandsa9cc3892010-04-21 13:51:48 +0000[diff] [blame]249DragonEgg is a new project which is seeing its first release with llvm-2.7.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]250</p>
251
252</div>
253
254
255<!--=========================================================================-->
256<div class="doc_subsection">
257<a name="mc">llvm-mc: Machine Code Toolkit</a>
258</div>
259
260<div class="doc_text">
261<p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]262The LLVM Machine Code (aka MC) sub-project of LLVM was created to solve a number
263of problems in the realm of assembly, disassembly, object file format handling,
264and a number of other related areas that CPU instruction-set level tools work
265in. It is a sub-project of LLVM which provides it with a number of advantages
266over other compilers that do not have tightly integrated assembly-level tools.
267For a gentle introduction, please see the <a
268href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
269LLVM MC Project Blog Post</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]270</p>
271
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]272<p>2.7 includes major parts of the work required by the new MC Project. A few
273 targets have been refactored to support it, and work is underway to support a
274 native assembler in LLVM. This work is not complete in LLVM 2.7, but you has
275 made substantially more progress on LLVM mainline.</p>
276
277<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]278 X86 .s file into intel syntax. You can do this with something like:</p>
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]279<pre>
280 llvm-mc foo.s -output-asm-variant=1 -o foo-intel.s
281</pre>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]282
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]283</div>
284
285
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]286<!-- *********************************************************************** -->
287<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]288 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]289</div>
290<!-- *********************************************************************** -->
291
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]292<div class="doc_text">
293
294<p>An exciting aspect of LLVM is that it is used as an enabling technology for
295 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]296 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]297</div>
298
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]299<!--=========================================================================-->
300<div class="doc_subsection">
301<a name="pure">Pure</a>
302</div>
303
304<div class="doc_text">
305<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]306<a href="http://pure-lang.googlecode.com/">Pure</a>
307is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]308Programs are collections of equations which are used to evaluate expressions in
309a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]310lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]311built-in list and matrix support (including list and matrix comprehensions) and
312an easy-to-use C interface. The interpreter uses LLVM as a backend to
313 JIT-compile Pure programs to fast native code.</p>
314
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]315<p>Pure versions 0.43 and later have been tested and are known to work with
316LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
317
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]318</div>
319
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]320<!--=========================================================================-->
321<div class="doc_subsection">
322<a name="RoadsendPHP">Roadsend PHP</a>
323</div>
324
325<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]326<p>
327<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattner9e08de12009-03-02 19:07:24 +0000[diff] [blame]328source implementation of the PHP programming
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]329language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]330reimplementation of an earlier project that is now based on LLVM.
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]331</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]332</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]333
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]334<!--=========================================================================-->
335<div class="doc_subsection">
336<a name="UnladenSwallow">Unladen Swallow</a>
337</div>
338
339<div class="doc_text">
340<p>
341<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
342branch of <a href="http://python.org/">Python</a> intended to be fully
343compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattnerd7db82c2010-03-18 06:52:15 +0000[diff] [blame]344compiler.
Chris Lattnere5236102010-03-17 04:02:39 +0000[diff] [blame]345</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]346</div>
347
348<!--=========================================================================-->
349<div class="doc_subsection">
Chris Lattner49894862010-03-29 17:50:39 +0000[diff] [blame]350<a name="tce">TTA-based Codesign Environment (TCE)</a>
351</div>
352
353<div class="doc_text">
354<p>
355<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
356application-specific processors (ASP) based on the Transport triggered
357architecture (TTA). The toolset provides a complete co-design flow from C/C++
358programs down to synthesizable VHDL and parallel program binaries. Processor
359customization points include the register files, function units, supported
360operations, and the interconnection network.</p>
361
362<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
363independent optimizations and also for parts of code generation. It generates
364new LLVM-based code generators "on the fly" for the designed TTA processors and
365loads them in to the compiler backend as runtime libraries to avoid per-target
366recompilation of larger parts of the compiler chain.</p>
367
368</div>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]369
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]370<!--=========================================================================-->
371<div class="doc_subsection">
372<a name="safecode">SAFECode Compiler</a>
373</div>
374
375<div class="doc_text">
376<p>
377<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
378compiler built using LLVM. It takes standard, unannotated C code, analyzes the
379code to ensure that memory accesses and array indexing operations are safe, and
380instruments the code with run-time checks when safety cannot be proven
381statically.
382</p>
383</div>
384
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]385<!--=========================================================================-->
386<div class="doc_subsection">
387<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
388</div>
John Criswelle75f04f2010-04-06 14:52:14 +0000[diff] [blame]389
Chris Lattner73372af2010-04-22 17:28:36 +0000[diff] [blame]390<div class="doc_text">
391<p>
392<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
393harness to build OpenJDK using only free software build tools and to provide
394replacements for the not-yet free parts of OpenJDK. One of the extensions that
395IcedTea provides is a new JIT compiler named <a
396href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
397to provide native code generation without introducing processor-dependent
398code.
399</p>
400<p>Icedtea6 1.8 and later have been tested and are known to work with
401LLVM 2.7 (and continue to work with older LLVM releases >= 2.6 as well).
402</p>
403</div>
404
405<!--=========================================================================-->
406<div class="doc_subsection">
407<a name="llvm-lua">LLVM-Lua</a>
408</div>
409
410<div class="doc_text">
411<p>
412<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM
413 to add JIT and static compiling support to the Lua VM. Lua
414bytecode is analyzed to remove type checks, then LLVM is used to compile the
415bytecode down to machine code.
416</p>
417<p>LLVM-Lua 1.2.0 have been tested and is known to work with LLVM 2.7.
418</p>
419</div>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]420<!-- *********************************************************************** -->
421<div class="doc_section">
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]422 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]423</div>
424<!-- *********************************************************************** -->
425
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]426<div class="doc_text">
427
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]428<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]429minor improvements. Some of the major improvements and new features are listed
430in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]431</p>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]432
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]433</div>
434
435<!--=========================================================================-->
436<div class="doc_subsection">
437<a name="orgchanges">LLVM Community Changes</a>
438</div>
439
440<div class="doc_text">
441
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]442<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
443organization changes have happened:
444</p>
445
446<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]447<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]448
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]449<li>Ted Kremenek and Doug Gregor have stepped forward as <a
450 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]451 Clang static analyzer and the Clang frontend, respectively.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]452
453<li>LLVM now has an <a href="http://blog.llvm.org">official Blog</a> at
454 <a href="http://blog.llvm.org">http://blog.llvm.org</a>. This is a great way
455 to learn about new LLVM-related features as they are implemented. Several
456 features in this release are already explained on the blog.</li>
457
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]458<li>The LLVM web pages are now checked into the SVN server, in the "www",
459 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]460 largely inaccessible old CVS server.</li>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]461
462<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
463 faster) server. It is still graciously hosted at the University of Illinois
464 of Urbana Champaign.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]465</ul>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]466</div>
467
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]468<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]469<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]470<a name="majorfeatures">Major New Features</a>
471</div>
472
473<div class="doc_text">
474
Jeffrey Yasskin8ee1b0a2010-01-28 01:14:43 +0000[diff] [blame]475<p>LLVM 2.7 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]476
477<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]478<li>2.7 includes initial support for the <a
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]479 href="http://en.wikipedia.org/wiki/MicroBlaze">MicroBlaze</a> target.
480 MicroBlaze is a soft processor core designed for Xilinx FPGAs.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]481
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]482<li>2.7 includes a new LLVM IR "extensible metadata" feature. This feature
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]483 supports many different use cases, including allowing front-end authors to
484 encode source level information into LLVM IR, which is consumed by later
485 language-specific passes. This is a great way to do high-level optimizations
486 like devirtualization, type-based alias analysis, etc. See the <a
487 href="http://blog.llvm.org/2010/04/extensible-metadata-in-llvm-ir.html">
488 Extensible Metadata Blog Post</a> for more information.</li>
489
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]490<li>2.7 encodes <a href="SourceLevelDebugging.html">debug information</a>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]491in a completely new way, built on extensible metadata. The new implementation
492is much more memory efficient and paves the way for improvements to optimized
493code debugging experience.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]494
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]495<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]496 indirect branch through a pointer. This is particularly useful for
497 interpreter loops, and is used to implement the GCC "address of label"
498 extension. For more information, see the <a
499href="http://blog.llvm.org/2010/01/address-of-label-and-indirect-branches.html">
500Address of Label and Indirect Branches in LLVM IR Blog Post</a>.
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]501
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]502<li>2.7 is the first release to start supporting APIs for assembling and
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]503 disassembling target machine code. These APIs are useful for a variety of
504 low level clients, and are surfaced in the new "enhanced disassembly" API.
505 For more information see the <a
506 href="http://blog.llvm.org/2010/01/x86-disassembler.html">The X86
507 Disassembler Blog Post</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]508
Chris Lattnerfa63e262010-04-22 06:38:11 +0000[diff] [blame]509<li>2.7 includes major parts of the work required by the new MC Project,
510 see the <a href="#mc">MC update above</a> for more information.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]511
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]512</ul>
Chris Lattner2b656342010-03-17 06:41:58 +0000[diff] [blame]513
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]514</div>
515
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]516<!--=========================================================================-->
517<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]518<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]519</div>
520
521<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]522<p>LLVM IR has several new features for better support of new targets and that
523expose new optimization opportunities:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]524
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]525<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]526<li>LLVM IR now supports a 16-bit "half float" data type through <a
527 href="LangRef.html#int_fp16">two new intrinsics</a> and APFloat support.</li>
528<li>LLVM IR supports two new <a href="LangRef.html#fnattrs">function
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]529 attributes</a>: inlinehint and alignstack(n). The former is a hint to the
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]530 optimizer that a function was declared 'inline' and thus the inliner should
531 weight it higher when considering inlining it. The later
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]532 indicates to the code generator that the function diverges from the platform
533 ABI on stack alignment.</li>
534<li>The new <a href="LangRef.html#int_objectsize">llvm.objectsize</a> intrinsic
535 allows the optimizer to infer the sizes of memory objects in some cases.
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]536 This intrinsic is used to implement the GCC <tt>__builtin_object_size</tt>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]537 extension.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]538<li>LLVM IR now supports marking load and store instructions with <a
539 href="LangRef.html#i_load">"non-temporal" hints</a> (building on the new
540 metadata feature). This hint encourages the code
541 generator to generate non-temporal accesses when possible, which are useful
542 for code that is carefully managing cache behavior. Currently, only the
543 X86 backend provides target support for this feature.</li>
544
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]545<li>LLVM 2.7 has pre-alpha support for <a
Gabor Greifdd39cd12010-04-22 10:11:24 +0000[diff] [blame]546 href="LangRef.html#t_union">unions in LLVM IR</a>.
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]547 Unfortunately, this support is not really usable in 2.7, so if you're
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]548 interested in pushing it forward, please help contribute to LLVM mainline.</li>
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]549
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]550</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]551
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]552</div>
553
554<!--=========================================================================-->
555<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]556<a name="optimizer">Optimizer Improvements</a>
557</div>
558
559<div class="doc_text">
560
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]561<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]562release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]563
564<ul>
565
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]566<li>The inliner reuses now merges arrays stack objects in different callees when
567 inlining multiple call sites into one function. This reduces the stack size
568 of the resultant function.</li>
569<li>The -basicaa alias analysis pass (which is the default) has been improved to
570 be less dependent on "type safe" pointers. It can now look through bitcasts
571 and other constructs more aggressively, allowing better load/store
572 optimization.</li>
573<li>The load elimination optimization in the GVN Pass [<a
574href="http://blog.llvm.org/2009/12/introduction-to-load-elimination-in-gvn.html">intro
575 blog post</a>] has been substantially improved to be more aggressive about
576 partial redundancy elimination and do more aggressive phi translation. Please
577 see the <a
578 href="http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html">
579 Advanced Topics in Redundant Load Elimination with a Focus on PHI Translation
580 Blog Post</a> for more details.</li>
581<li>The module <a href="LangRef.html#datalayout">target data string</a> now
Wesley Peck63c86992010-04-22 13:28:34 +0000[diff] [blame]582 includes a notion of 'native' integer data types for the target. This
583 helps mid-level optimizations avoid promoting complex sequences of
584 operations to data types that are not natively supported (e.g. converting
585 i32 operations to i64 on 32-bit chips).</li>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]586<li>The mid-level optimizer is now conservative when operating on a module with
587 no target data. Previously, it would default to SparcV9 settings, which is
588 not what most people expected.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]589<li>Jump threading is now much more aggressive at simplifying correlated
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]590 conditionals and threading blocks with otherwise complex logic. It has
591 subsumed the old "Conditional Propagation" pass, and -condprop has been
592 removed from LLVM 2.7.</li>
593<li>The -instcombine pass has been refactored from being one huge file to being
594 a library of its own. Internally, it uses a customized IRBuilder to clean
595 it up and simplify it.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]596
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]597<li>The optimal edge profiling pass is reliable and much more complete than in
598 2.6. It can be used with the llvm-prof tool but isn't wired up to the
599 llvm-gcc and clang command line options yet.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]600
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]601<li>A new experimental alias analysis implementation, -scev-aa, has been added.
602 It uses LLVM's Scalar Evolution implementation to do symbolic analysis of
603 pointer offset expressions to disambiguate pointers. It can catch a few
604 cases that basicaa cannot, particularly in complex loop nests.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]605
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]606<li>The default pass ordering has been tweaked for improved optimization
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]607 effectiveness.</li>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]608
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]609</ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]610
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]611</div>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]612
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]613
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]614<!--=========================================================================-->
615<div class="doc_subsection">
616<a name="executionengine">Interpreter and JIT Improvements</a>
617</div>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]618
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]619<div class="doc_text">
620
621<ul>
Wesley Peck0d7f61e2010-04-22 13:36:27 +0000[diff] [blame]622<li>The JIT now supports generating debug information and is compatible with
623the new GDB 7.0 (and later) interfaces for registering dynamically generated
624debug info.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]625
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]626<li>The JIT now <a href="http://llvm.org/PR5184">defaults
Jeffrey Yasskin40715142010-01-29 19:10:38 +0000[diff] [blame]627to compiling eagerly</a> to avoid a race condition in the lazy JIT.
628Clients that still want the lazy JIT can switch it on by calling
629<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]630
Jeffrey Yasskinc0577082010-02-11 01:07:39 +0000[diff] [blame]631<li>It is now possible to create more than one JIT instance in the same process.
632These JITs can generate machine code in parallel,
633although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
634still have to obey the other threading restrictions</a>.</li>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]635
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]636</ul>
637
638</div>
639
640<!--=========================================================================-->
641<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]642<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]643</div>
644
645<div class="doc_text">
646
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]647<p>We have put a significant amount of work into the code generator
648infrastructure, which allows us to implement more aggressive algorithms and make
649it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]650
651<ul>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]652<li>The 'llc -asm-verbose' option (which is now the default) has been enhanced
653 to emit many useful comments to .s files indicating information about spill
654 slots and loop nest structure. This should make it much easier to read and
655 understand assembly files. This is wired up in llvm-gcc and clang to
656 the <tt>-fverbose-asm</tt> option.</li>
657
658<li>New LSR with "full strength reduction" mode. FIXME: Description?</li>
659
660<li>A new codegen level Common Subexpression Elimination pass (MachineCSE)
661 is available and enabled by default. It catches redundancies exposed by
662 lowering.</li>
663<li>A new pre-register-allocation tail duplication pass is available and enabled
664 by default, it can substantially improve branch prediction quality in some
665 cases.</li>
666<li>A new sign and zero extension optimization pass (OptimizeExtsPass)
667 is available and enabled by default. This pass can takes advantage
668 architecture features like x86-64 implicit zero extension behavior and
669 sub-registers.</li>
670<li>The code generator now supports a mode where it attempts to preserve the
671 order of instructions in the input code. This is important for source that
672 is hand scheduled and extremely sensitive to scheduling. It is compatible
673 with the GCC <tt>-fno-schedule-insns</tt> option.</li>
674<li>The target-independent code generator now supports generating code with
675 arbitrary numbers of result values. Returning more values than was
676 previously supported is handled by returning through a hidden pointer. In
677 2.7, only the X86 and XCore targets have adopted support for this
678 though.</li>
679<li>The code generator now supports generating code that follows the
680 <a href="LangRef.html#callingconv">Glasgow Haskell Compiler Calling
681 Convention</a> and ABI.</li>
682<li>The "<a href="CodeGenerator.html#selectiondag_select">DAG instruction
683 selection</a>" phase of the code generator has been largely rewritten for
684 2.7. Previously, tblgen spit out tons of C++ code which was compiled and
685 linked into the target to do the pattern matching, now it emits a much
686 smaller table which is read by the target-independent code. The primary
687 advantages of this approach is that the size and compile time of various
688 targets is much improved. The X86 code generator shrunk by 1.5MB of code,
689 for example.</li>
690<li>Almost the entire code generator has switched to emitting code through the
691 MC interfaces instead of printing textually to the .s file. This led to a
692 number of cleanups and speedups. In 2.7, debug an exception handling
693 information does not go through MC yet.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]694</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]695</div>
696
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]697<!--=========================================================================-->
698<div class="doc_subsection">
699<a name="x86">X86-32 and X86-64 Target Improvements</a>
700</div>
701
702<div class="doc_text">
703<p>New features of the X86 target include:
704</p>
705
706<ul>
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]707<li>The X86 backend now optimizes tails calls much more aggressively for
708 functions that use the standard C calling convention.</li>
709<li>The X86 backend now models scalar SSE registers as subregs of the SSE vector
710 registers, making the code generator more aggressive in cases where scalars
711 and vector types are mixed.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]712
Chris Lattner556aac32010-04-21 06:42:24 +0000[diff] [blame]713<li>PostRA scheduler for X86? FIXME: is this on by default in 2.7?</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]714
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]715</ul>
716
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]717</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]718
719<!--=========================================================================-->
720<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]721<a name="ARM">ARM Target Improvements</a>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]722</div>
723
724<div class="doc_text">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]725<p>New features of the ARM target include:
726</p>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]727
728<ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]729
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]730<li>The ARM backend now generates instructions in unified assembly syntax.</li>
731
732<li>llvm-gcc now has complete support for the ARM v7 NEON instruction set. This
733 support differs slightly from the GCC implementation. Please see the
734 <a
735href="http://blog.llvm.org/2010/04/arm-advanced-simd-neon-intrinsics-and.html">
736 ARM Advanced SIMD (NEON) Intrinsics and Types in LLVM Blog Post</a> for
737 helpful information if migrating code from GCC to LLVM-GCC.</li>
738
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]739<li>The ARM and Thumb code generators now use register scavenging for stack
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]740 object address materialization.(FIXME: WHAT BENEFIT DOES THIS PROVIDE?)</li>
741
Wesley Peck0e9beac2010-04-22 13:43:14 +0000[diff] [blame]742<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]743 on StrongARM hardware. Previously, LLVM only supported ARMv4T and
744 newer chips.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]745</ul>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]746
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]747
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]748</div>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]749
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]750<!--=========================================================================-->
751<div class="doc_subsection">
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]752<a name="newapis">New Useful APIs</a>
753</div>
754
755<div class="doc_text">
756
757<p>This release includes a number of new APIs that are used internally, which
758 may also be useful for external clients.
759</p>
760
761<ul>
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]762<li>The optimizer uses the new CodeMetrics class to measure the size of code.
Chris Lattner9d966ed2010-04-22 17:39:38 +0000[diff] [blame]763 Various passes (like the inliner, loop unswitcher, etc) all use this to make
764 more accurate estimates of the code size impact of various
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]765 optimizations.</li>
766<li>A new <a href="http://llvm.org/doxygen/InstructionSimplify_8h-source.html">
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]767 llvm/Analysis/InstructionSimplify.h</a> interface is available for doing
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]768 symbolic simplification of instructions (e.g. <tt>a+0</tt> -&gt; <tt>a</tt>)
769 without requiring the instruction to exist. This centralizes a lot of
770 ad-hoc symbolic manipulation code scattered in various passes.</li>
771<li>The optimizer now uses a new <a
772 href="http://llvm.org/doxygen/SSAUpdater_8h-source.html">SSAUpdater</a>
773 class which efficiently supports
774 doing unstructured SSA update operations. This centralized a bunch of code
Wesley Peck7b6a2ec2010-04-22 13:50:46 +0000[diff] [blame]775 scattered throughout various passes (e.g. jump threading, lcssa,
776 loop rotate, etc) for doing this sort of thing. The code generator has a
777 similar <a href="http://llvm.org/doxygen/MachineSSAUpdater_8h-source.html">
Chris Lattnerabfaf732010-04-22 05:41:35 +0000[diff] [blame]778 MachineSSAUpdater</a> class.</li>
779<li>The <a href="http://llvm.org/doxygen/Regex_8h-source.html">
780 llvm/Support/Regex.h</a> header exposes a platform independent regular
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]781 expression API. Building on this, the <a
782 href="TestingGuide.html#FileCheck">FileCheck</a> utility now supports
783 regular exressions.</li>
784<li>raw_ostream now supports a circular "debug stream" accessed with "dbgs()".
785 By default, this stream works the same way as "errs()", but if you pass
786 <tt>-debug-buffer-size=1000</tt> to opt, the debug stream is capped to a
787 fixed sized circular buffer and the output is printed at the end of the
788 program's execution. This is helpful if you have a long lived compiler
789 process and you're interested in seeing snapshots in time.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]790</ul>
791
792
793</div>
794
795<!--=========================================================================-->
796<div class="doc_subsection">
797<a name="otherimprovements">Other Improvements and New Features</a>
798</div>
799
800<div class="doc_text">
801<p>Other miscellaneous features include:</p>
802
803<ul>
Chris Lattner8a57e892010-04-21 06:23:40 +0000[diff] [blame]804<li>You can now build LLVM as a big dynamic library (e.g. "libllvm2.7.so"). To
805 get this, configure LLVM with the --enable-shared option.</li>
806
Wesley Pecka85292d2010-04-22 13:53:54 +0000[diff] [blame]807<li>LLVM command line tools now overwrite their output by default. Previously,
808 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]809 behave more like standard unix tools.</li>
810
811<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
812 file, and automatically do the right thing. This means you don't need to
813 explicitly use the llvm-as tool for most things.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]814</ul>
815
816</div>
817
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]818
819<!--=========================================================================-->
820<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]821<a name="changes">Major Changes and Removed Features</a>
822</div>
823
824<div class="doc_text">
825
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]826<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]827on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]828from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]829
830<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]831
832<li>
833The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
834("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
835profiling ("rsprofiling") passes have all been removed. They were not being
836actively maintained and had substantial problems. If you are interested in
837these components, you are welcome to ressurect them from SVN, fix the
838correctness problems, and resubmit them to mainline.</li>
839
840<li>LLVM now defaults to building most libraries with RTTI turned off, providing
841a code size reduction. Packagers who are interested in building LLVM to support
842plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
843and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
844document.</li>
845
Jeffrey Yasskin260af332010-02-09 23:03:44 +0000[diff] [blame]846<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
847if you have it installed. This makes it more likely that an LLVM built on one
848system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]849configure with <tt>--enable-libffi</tt>.</li>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]850
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]851<li>Debug information uses a completely different representation, an LLVM 2.6
852.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
853
854<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
855 along with LowerAllocations pass. Now you should just use a call to the
856 malloc and free functions in libc. These calls are optimized as well as
857 the old instructions were.</li>
858</ul>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]859
860<p>In addition, many APIs have changed in this release. Some of the major LLVM
861API changes are:</p>
862
863<ul>
Chris Lattner6fd928d2010-04-21 05:17:40 +0000[diff] [blame]864<li>Just about everything has been converted to use raw_ostream instead of
865 std::ostream.</li>
866<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
867 instead.</li>
868<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
869 instead.</li>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]870<li>The TargetAsmInfo interface was renamed to MCAsmInfo.</li>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]871<li><tt>ModuleProvider</tt> has been <a
Gabor Greif92d28ea2010-04-22 10:21:43 +0000[diff] [blame]872href="http://llvm.org/viewvc/llvm-project?view=rev&amp;revision=94686">removed</a>
Jeffrey Yasskin2ca16212010-01-28 01:41:20 +0000[diff] [blame]873and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
874Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
875replace <tt>getBitcodeModuleProvider</tt> with
876<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
877functions that used to accept <tt>ModuleProvider</tt>. Clients who
878wrote their own <tt>ModuleProvider</tt>s will need to derive from
879<tt>GVMaterializer</tt> instead and use
880<tt>Module::setMaterializer</tt> to attach it to a
881<tt>Module</tt>.</li>
882
883<li><tt>GhostLinkage</tt> has given up the ghost.
884<tt>GlobalValue</tt>s that have not yet been read from their backing
885storage have the same linkage they will have after being read in.
886Clients must replace calls to
887<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
888<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar61f41422010-02-10 04:09:52 +0000[diff] [blame]889
Duncan Sandsdd29fc82010-02-17 17:20:17 +0000[diff] [blame]890<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
891<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
892<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
893<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Chris Lattner43f7a1d2010-04-22 17:25:00 +0000[diff] [blame]894
895<li><tt>llvm::Instruction::clone()</tt> no longer takes argument.</li>
896<li><tt>raw_fd_ostream</tt>'s constructor now takes a flag argument, not individual
897 booleans (see <tt>include/llvm/Support/raw_ostream.h</tt> for details).</li>
898<li>Some header files have been renamed:
899<ul>
900 <li><tt>llvm/Support/AIXDataTypesFix.h</tt> to
901 <tt>llvm/System/AIXDataTypesFix.h</tt></li>
902 <li><tt>llvm/Support/DataTypes.h</tt> to <tt>llvm/System/DataTypes.h</tt></li>
903 <li><tt>llvm/Transforms/Utils/InlineCost.h</tt> to
904 <tt>llvm/Analysis/InlineCost.h</tt></li>
905 <li><tt>llvm/Support/Mangler.h</tt> to <tt>llvm/Target/Mangler.h</tt></li>
906 <li><tt>llvm/Analysis/Passes.h</tt> to <tt>llvm/CodeGen/Passes.h</tt></li>
907</ul></li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]908</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]909
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]910</div>
911
912
913
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]914<!-- *********************************************************************** -->
915<div class="doc_section">
916 <a name="portability">Portability and Supported Platforms</a>
917</div>
918<!-- *********************************************************************** -->
919
920<div class="doc_text">
921
922<p>LLVM is known to work on the following platforms:</p>
923
924<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]925<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]926 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
927 systems).</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]928<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]929 and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]930<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]931<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
932 support is available for native builds with Visual C++).</li>
Chris Lattner9235ce52009-10-16 16:30:58 +0000[diff] [blame]933<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]934<li>Alpha-based machines running Debian GNU/Linux.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]935</ul>
936
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]937<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]938to the machine and operating system on which it is built. However, minor
939porting may be required to get LLVM to work on new platforms. We welcome your
940portability patches and reports of successful builds or error messages.</p>
941
942</div>
943
944<!-- *********************************************************************** -->
945<div class="doc_section">
946 <a name="knownproblems">Known Problems</a>
947</div>
948<!-- *********************************************************************** -->
949
950<div class="doc_text">
951
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]952<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]953listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]954href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
955there isn't already one.</p>
956
Chris Lattner1f8dc512010-03-17 17:25:49 +0000[diff] [blame]957<ul>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]958<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
959using the stock GCC 3.x.x series 'out the box',
Chris Lattnerc09ffd22009-11-03 21:50:09 +0000[diff] [blame]960See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]961However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
962for x86/x86-64 has been made available from the third party AuroraUX Project
963that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
964</ul>
965
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]966</div>
967
968<!-- ======================================================================= -->
969<div class="doc_subsection">
970 <a name="experimental">Experimental features included with this release</a>
971</div>
972
973<div class="doc_text">
974
975<p>The following components of this LLVM release are either untested, known to
976be broken or unreliable, or are in early development. These components should
977not be relied on, and bugs should not be filed against them, but they may be
978useful 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]979components, please contact us on the <a
980href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]981
982<ul>
Wesley Peckbe6dc822010-03-18 14:31:30 +0000[diff] [blame]983<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
984 backends are experimental.</li>
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]985<li><tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]986 supported value for this option. The MachO writer is experimental, and
987 works much better in mainline SVN.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]988</ul>
989
990</div>
991
992<!-- ======================================================================= -->
993<div class="doc_subsection">
994 <a name="x86-be">Known problems with the X86 back-end</a>
995</div>
996
997<div class="doc_text">
998
999<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]1000 <li>The X86 backend does not yet support
1001 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1002 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1003 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1004 <li>The X86 backend generates inefficient floating point code when configured
1005 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]1006 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1007 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1008 runtime currently due to lack of support for the 'u' inline assembly
1009 constraint and for X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1010 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner8f33c262010-04-22 06:28:20 +0000[diff] [blame]1011 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]1012 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1013</ul>
1014
1015</div>
1016
1017<!-- ======================================================================= -->
1018<div class="doc_subsection">
1019 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1020</div>
1021
1022<div class="doc_text">
1023
1024<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1025<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1026compilation, and lacks support for debug information.</li>
1027</ul>
1028
1029</div>
1030
1031<!-- ======================================================================= -->
1032<div class="doc_subsection">
1033 <a name="arm-be">Known problems with the ARM back-end</a>
1034</div>
1035
1036<div class="doc_text">
1037
1038<ul>
1039<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]1040processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1041results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1042<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1043</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1044</ul>
1045
1046</div>
1047
1048<!-- ======================================================================= -->
1049<div class="doc_subsection">
1050 <a name="sparc-be">Known problems with the SPARC back-end</a>
1051</div>
1052
1053<div class="doc_text">
1054
1055<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1056<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]1057 support the 64-bit SPARC ABI (-m64).</li>
1058</ul>
1059
1060</div>
1061
1062<!-- ======================================================================= -->
1063<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1064 <a name="mips-be">Known problems with the MIPS back-end</a>
1065</div>
1066
1067<div class="doc_text">
1068
1069<ul>
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]1070<li>64-bit MIPS targets are not supported yet.</li>
1071</ul>
1072
1073</div>
1074
1075<!-- ======================================================================= -->
1076<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1077 <a name="alpha-be">Known problems with the Alpha back-end</a>
1078</div>
1079
1080<div class="doc_text">
1081
1082<ul>
1083
1084<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1085appropriate nops inserted to ensure restartability.</li>
1086
1087</ul>
1088</div>
1089
1090<!-- ======================================================================= -->
1091<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1092 <a name="c-be">Known problems with the C back-end</a>
1093</div>
1094
1095<div class="doc_text">
1096
1097<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1098<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1099 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]1100<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1101 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]1102 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]1103<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]1104<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1105</ul>
1106
1107</div>
1108
1109
1110<!-- ======================================================================= -->
1111<div class="doc_subsection">
Chris Lattner58b1d0f2010-03-17 04:41:49 +0000[diff] [blame]1112 <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]1113</div>
1114
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1115<div class="doc_text">
1116
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1117<p>The only major language feature of GCC not supported by llvm-gcc is
1118 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1119 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1120 supported on some targets (these are used when you take the address of a
1121 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1122
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1123</div>
1124
1125<!-- ======================================================================= -->
1126<div class="doc_subsection">
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1127 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1128</div>
1129
1130<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1131<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1132<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1133 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1134 tools/gfortran component for details.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]1135</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]1136</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1137
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1138<!-- ======================================================================= -->
1139<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]1140 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1141</div>
1142
1143<div class="doc_text">
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame]1144The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1145technology, and problems should be expected.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1146<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]1147<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]1148to lack of trampoline support (pointers to nested functions) on other platforms.
1149However, 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]1150which does support trampolines.</li>
1151<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]1152This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1153exception handling, which is used internally by the compiler.
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1154Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]1155<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1156and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]1157(c380004 also fails with gcc-4.2 mainline).
1158If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1159causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsc2a29a02009-03-02 16:35:57 +0000[diff] [blame]1160<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner0b6ea7a2009-10-13 17:48:04 +0000[diff] [blame]1161<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1162<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]1163crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1164<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1165or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1166or use representation clauses that result in a field of a non-discrete type
1167starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]1168<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1169'main' as generated by the Ada binder to be invalid</a>.
1170Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1171<tt>envp</tt> rather than integers.</li>
1172<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1173ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]1174</ul>
1175</div>
1176
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1177<!-- *********************************************************************** -->
1178<div class="doc_section">
1179 <a name="additionalinfo">Additional Information</a>
1180</div>
1181<!-- *********************************************************************** -->
1182
1183<div class="doc_text">
1184
1185<p>A wide variety of additional information is available on the <a
1186href="http://llvm.org">LLVM web page</a>, in particular in the <a
1187href="http://llvm.org/docs/">documentation</a> section. The web page also
1188contains versions of the API documentation which is up-to-date with the
1189Subversion version of the source code.
1190You can access versions of these documents specific to this release by going
1191into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1192
1193<p>If you have any questions or comments about LLVM, please feel free to contact
1194us via the <a href="http://llvm.org/docs/#maillist"> mailing
1195lists</a>.</p>
1196
1197</div>
1198
1199<!-- *********************************************************************** -->
1200
1201<hr>
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1207
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