Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 9cbe2bc74aff10a95b2ee6ed6fb4a47dffee4751 / . / docs / ReleaseNotes-2.6.html
blob: 6e51aef70a6de3eb540ad4812569d63647ba02d8 [file] [log] [blame]
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7 <title>LLVM 2.6 Release Notes</title>
8</head>
9<body>
10
11<div class="doc_title">LLVM 2.6 Release Notes</div>
12
13<ol>
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#subproj">Sub-project Status Update</a></li>
16 <li><a href="#externalproj">External Projects Using LLVM 2.6</a></li>
17 <li><a href="#whatsnew">What's New in LLVM 2.6?</a></li>
18 <li><a href="GettingStarted.html">Installation Instructions</a></li>
19 <li><a href="#portability">Portability and Supported Platforms</a></li>
20 <li><a href="#knownproblems">Known Problems</a></li>
21 <li><a href="#additionalinfo">Additional Information</a></li>
22</ol>
23
24<div class="doc_author">
25 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
26</div>
27
28<!-- *********************************************************************** -->
29<div class="doc_section">
30 <a name="intro">Introduction</a>
31</div>
32<!-- *********************************************************************** -->
33
34<div class="doc_text">
35
36<p>This document contains the release notes for the LLVM Compiler
37Infrastructure, release 2.6. Here we describe the status of LLVM, including
38major improvements from the previous release and significant known problems.
39All LLVM releases may be downloaded from the <a
40href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
41
42<p>For more information about LLVM, including information about the latest
43release, please check out the <a href="http://llvm.org/">main LLVM
44web site</a>. If you have questions or comments, the <a
45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
46List</a> is a good place to send them.</p>
47
48<p>Note that if you are reading this file from a Subversion checkout or the
49main LLVM web page, this document applies to the <i>next</i> release, not the
50current one. To see the release notes for a specific release, please see the
51<a href="http://llvm.org/releases/">releases page</a>.</p>
52
53</div>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]54
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]55
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]56<!--
57Almost dead code.
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]58 include/llvm/Analysis/LiveValues.h => Dan
59 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
60 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]61-->
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]62
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]63
64<!-- Unfinished features in 2.6:
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]65 gcc plugin.
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]66 strong phi elim
67 variable debug info for optimized code
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]68 postalloc scheduler: anti dependence breaking, hazard recognizer?
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]69 metadata
70 loop dependence analysis
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]71 ELF Writer? How stable?
72 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]73 2.7 supports the GDB 7.0 jit interfaces for debug info.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]74 -->
75
76 <!-- for announcement email:
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]77 Logo web page.
78 llvm devmtg
79 compiler_rt
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]80 KLEE web page at klee.llvm.org
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]81 Many new papers added to /pubs/
82 Mention gcc plugin.
83
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]84 -->
85
86<!-- *********************************************************************** -->
87<div class="doc_section">
88 <a name="subproj">Sub-project Status Update</a>
89</div>
90<!-- *********************************************************************** -->
91
92<div class="doc_text">
93<p>
94The LLVM 2.6 distribution currently consists of code from the core LLVM
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]95repository (which roughly includes the LLVM optimizers, code generators
96and supporting tools), the Clang repository and the llvm-gcc repository. In
97addition to this code, the LLVM Project includes other sub-projects that are in
98development. Here we include updates on these subprojects.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]99</p>
100
101</div>
102
103
104<!--=========================================================================-->
105<div class="doc_subsection">
106<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
107</div>
108
109<div class="doc_text">
110
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]111<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
112a set of new 'LLVM native' front-end technologies for the C family of languages.
113LLVM 2.6 is the first release to officially include Clang, and it provides a
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]114production quality C and Objective-C compiler. If you are interested in <a
115href="http://clang.llvm.org/performance.html">fast compiles</a> and
116<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
117encourage you to try it out. Clang currently compiles typical Objective-C code
1183x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
119(which is when the most pressure is on the frontend).</p>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]120
121<p>In addition to supporting these languages, C++ support is also <a
122href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
123Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
124If you are interested in Clang C++ support or any other Clang feature, we
125strongly encourage you to get involved on the <a
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]126href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
127list</a>.</p>
128
129<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
130
131<ul>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]132<li>C and Objective-C support are now considered production quality.</li>
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]133<li>AuroraUX, FreeBSD and OpenBSD are now supported.</li>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]134<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]135<li>Many many bugs are fixed and lots of features have been added.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]136</ul>
137</div>
138
139<!--=========================================================================-->
140<div class="doc_subsection">
141<a name="clangsa">Clang Static Analyzer</a>
142</div>
143
144<div class="doc_text">
145
Ted Kremenek0c5465e2009-10-11 03:10:25 +0000[diff] [blame]146<p>Previously announced in the 2.4 and 2.5 LLVM releases, the Clang project also
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]147includes an early stage static source code analysis tool for <a
148href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Duncan Sandsccedda42009-10-10 19:16:25 +0000[diff] [blame]149in C and Objective-C programs. The tool performs checks to find
Ted Kremenek0c5465e2009-10-11 03:10:25 +0000[diff] [blame]150bugs that occur on a specific path within a program.</p>
151
152<p>In the LLVM 2.6 time-frame, the analyzer core has undergone several important
153improvements and cleanups and now includes a new <em>Checker</em> interface that
154is intended to eventually serve as a basis for domain-specific checks. Further,
155in addition to generating HTML files for reporting analysis results, the
156analyzer can now also emit bug reports in a structured XML format that is
157intended to be easily readable by other programs.</p>
158
159<p>The set of checks performed by the static analyzer continues to expand, and
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]160future plans for the tool include full source-level inter-procedural analysis
161and deeper checks such as buffer overrun detection. There are many opportunities
162to extend and enhance the static analyzer, and anyone interested in working on
163this project is encouraged to get involved!</p>
164
165</div>
166
167<!--=========================================================================-->
168<div class="doc_subsection">
169<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
170</div>
171
172<div class="doc_text">
173<p>
174The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]175a JVM and a CLI Virtual Machine (Microsoft .NET is an
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]176implementation of the CLI) using LLVM for static and just-in-time
177compilation.</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]178
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]179<p>
180VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
Duncan Sandsdc5bd2b2009-10-10 19:30:16 +0000[diff] [blame]181<a href="http://vmkit.llvm.org/releases/">web page</a>. The release includes
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]182bug fixes, cleanup and new features. The major changes are:</p>
183
184<ul>
185
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]186<li>A new llcj tool to generate shared libraries or executables of Java
187 files.</li>
Nicolas Geoffray13eff6a2009-10-09 13:17:57 +0000[diff] [blame]188<li>Cooperative garbage collection. </li>
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]189<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
Duncan Sandsdc5bd2b2009-10-10 19:30:16 +0000[diff] [blame]190<li>Implementation of a two-word header for Java objects instead of the original
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]191 three-word header. </li>
192<li>Better Java specification-compliance: division by zero checks, stack
193 overflow checks, finalization and references support. </li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]194
195</ul>
196</div>
197
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]198
199<!--=========================================================================-->
200<div class="doc_subsection">
201<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
202</div>
203
204<div class="doc_text">
205<p>
206The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
207is a simple library that provides an implementation of the low-level
208target-specific hooks required by code generation and other runtime components.
209For example, when compiling for a 32-bit target, converting a double to a 64-bit
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]210unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]211function. The compiler-rt library provides highly optimized implementations of
212this and other low-level routines (some are 3x faster than the equivalent
213libgcc routines).</p>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]214
215<p>
216All of the code in the compiler-rt project is available under the standard LLVM
217License, a "BSD-style" license.</p>
218
219</div>
220
221<!--=========================================================================-->
222<div class="doc_subsection">
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]223<a name="klee">KLEE: Symbolic Execution and Automatic Test Case Generator</a>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]224</div>
225
226<div class="doc_text">
227<p>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]228The new LLVM <a href="http://klee.llvm.org/">KLEE project</a> is a symbolic
229execution framework for programs in LLVM bitcode form. KLEE tries to
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]230symbolically evaluate "all" paths through the application and records state
231transitions that lead to fault states. This allows it to construct testcases
232that lead to faults and can even be used to verify algorithms. For more
233details, please see the <a
234href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]235KLEE.</p>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]236
237</div>
238
239<!--=========================================================================-->
240<div class="doc_subsection">
Duncan Sands8f506a92009-10-11 09:07:15 +0000[diff] [blame]241<a name="dragonegg">DragonEgg: GCC-4.5 as an LLVM frontend</a>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]242</div>
243
244<div class="doc_text">
245<p>
Duncan Sands8f506a92009-10-11 09:07:15 +0000[diff] [blame]246The goal of <a href="http://dragonegg.llvm.org/">DragonEgg</a> is to make
247gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever.
248DragonEgg is a shared library (llvm.so) that is loaded by gcc at runtime. It
249uses the new gcc plugin architecture to disable the GCC optimizers and code
250generators, and schedule the LLVM optimizers and code generators (or direct
251output of LLVM IR) instead. Currently only Linux and Darwin are supported,
252and only on x86-32 and x86-64. It should be easy to add additional unix-like
253architectures and other processor families. Since gcc-4.5 has not yet been
254released, neither has <a href="http://dragonegg.llvm.org/">DragonEgg</a>.
255To build <a href="http://dragonegg.llvm.org/">DragonEgg</a> you will need to
256check out the development versions of <a href="http://gcc.gnu.org/svn.html/">
257gcc</a>, <a href="http://llvm.org/docs/GettingStarted.html#checkout">llvm</a>
258and <a href="http://dragonegg.llvm.org/">DragonEgg</a> from their respective
259subversion repositories.
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]260</p>
261
262</div>
263
264
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]265<!--=========================================================================-->
266<div class="doc_subsection">
267<a name="mc">llvm-mc: Machine Code Toolkit</a>
268</div>
269
270<div class="doc_text">
271<p>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]272The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
273better tools for dealing with machine code, object file formats, etc. The idea
274is to be able to generate most of the target specific details of assemblers and
275disassemblers from existing LLVM target .td files (with suitable enhancements),
276and to build infrastructure for reading and writing common object file formats.
277One of the first deliverables is to build a full assembler and integrate it into
278the compiler, which is predicted to substantially reduce compile time in some
279scenarios.
280</p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]281
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]282<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
283can reliably parse and pretty print (with some encoding information) a
284darwin/x86 .s file successfully, and has the very early phases of a Mach-O
285assembler in progress. Beyond the MC framework itself, major refactoring of the
286LLVM code generator has started. The idea is to make the code generator reason
287about the code it is producing in a much more semantic way, rather than a
288textual way. For example, the code generator now uses MCSection objects to
289represent section assignments, instead of text strings that print to .section
290directives.</p>
291
292<p>MC is an early and ongoing project that will hopefully continue to lead to
293many improvements in the code generator and build infrastructure useful for many
294other situations.
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]295</p>
296
297</div>
298
299
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]300<!-- *********************************************************************** -->
301<div class="doc_section">
302 <a name="externalproj">External Projects Using LLVM 2.6</a>
303</div>
304<!-- *********************************************************************** -->
305
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]306<div class="doc_text">
307
308<p>An exciting aspect of LLVM is that it is used as an enabling technology for
309 a lot of other language and tools projects. This section lists some of the
310 projects that have already been updated to work with LLVM 2.6.</p>
311</div>
312
313
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]314<!--=========================================================================-->
315<div class="doc_subsection">
316<a name="Rubinius">Rubinius</a>
317</div>
318
319<div class="doc_text">
320<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
321for running Ruby code which strives to write as much of the core class
322implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
323uses LLVM to optimize and compile ruby code down to machine code. Techniques
324such as type feedback, method inlining, and uncommon traps are all used to
325remove dynamism from ruby execution and increase performance.</p>
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]326
327<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]328a counter based JIT, type feedback and speculative method inlining.
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]329</p>
330
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]331</div>
Chris Lattner2375deb2009-09-30 06:27:22 +0000[diff] [blame]332
333<!--=========================================================================-->
334<div class="doc_subsection">
335<a name="macruby">MacRuby</a>
336</div>
337
338<div class="doc_text">
339
340<p>
341<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
342core Mac OS X technologies, such as the Objective-C common runtime and garbage
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]343collector and the CoreFoundation framework. It is principally developed by
Chris Lattner2375deb2009-09-30 06:27:22 +0000[diff] [blame]344Apple and aims at enabling the creation of full-fledged Mac OS X applications.
345</p>
346
347<p>
348MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
349expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
350handling.</p>
351
352</div>
353
354
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]355<!--=========================================================================-->
356<div class="doc_subsection">
357<a name="pure">Pure</a>
358</div>
359
360<div class="doc_text">
361<p>
362<a href="http://pure-lang.googlecode.com/">Pure</a>
363is an algebraic/functional programming language based on term rewriting.
364Programs are collections of equations which are used to evaluate expressions in
365a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
366lexical closures, a hygienic macro system (also based on term rewriting),
367built-in list and matrix support (including list and matrix comprehensions) and
368an easy-to-use C interface. The interpreter uses LLVM as a backend to
369 JIT-compile Pure programs to fast native code.</p>
370
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]371<p>Pure versions 0.31 and later have been tested and are known to work with
372LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]373</p>
374</div>
375
376
377<!--=========================================================================-->
378<div class="doc_subsection">
379<a name="ldc">LLVM D Compiler</a>
380</div>
381
382<div class="doc_text">
383<p>
384<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
385the D Programming Language using the LLVM optimizer and code generator.
386The LDC project works great with the LLVM 2.6 release. General improvements in
387this
388cycle have included new inline asm constraint handling, better debug info
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]389support, general bug fixes and better x86-64 support. This has allowed
Chris Lattner8b04a442009-10-10 23:05:42 +0000[diff] [blame]390some major improvements in LDC, getting it much closer to being as
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]391fully featured as the original DMD compiler from DigitalMars.
392</p>
393</div>
394
395<!--=========================================================================-->
396<div class="doc_subsection">
397<a name="RoadsendPHP">Roadsend PHP</a>
398</div>
399
400<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]401<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]402<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]403source implementation of the PHP programming
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]404language that uses LLVM for its optimizer, JIT and static compiler. This is a
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]405reimplementation of an earlier project that is now based on LLVM.</p>
406</div>
407
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]408<!--=========================================================================-->
409<div class="doc_subsection">
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]410<a name="UnladenSwallow">Unladen Swallow</a>
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]411</div>
412
413<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]414<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]415<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]416branch of <a href="http://python.org/">Python</a> intended to be fully
417compatible and significantly faster. It uses LLVM's optimization passes and JIT
418compiler.</p>
419</div>
420
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]421<!--=========================================================================-->
422<div class="doc_subsection">
423<a name="llvm-lua">llvm-lua</a>
424</div>
425
426<div class="doc_text">
427<p>
428<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]429and static compiling support to the Lua VM. Lua bytecode is analyzed to
430remove type checks, then LLVM is used to compile the bytecode down to machine
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]431code.</p>
432</div>
433
Jeffrey Yasskin123b3922009-06-24 21:26:42 +0000[diff] [blame]434
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]435
436<!-- *********************************************************************** -->
437<div class="doc_section">
438 <a name="whatsnew">What's New in LLVM 2.6?</a>
439</div>
440<!-- *********************************************************************** -->
441
442<div class="doc_text">
443
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]444<p>This release includes a huge number of bug fixes, performance tweaks and
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]445minor improvements. Some of the major improvements and new features are listed
446in this section.
447</p>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]448
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]449</div>
450
451<!--=========================================================================-->
452<div class="doc_subsection">
453<a name="majorfeatures">Major New Features</a>
454</div>
455
456<div class="doc_text">
457
458<p>LLVM 2.6 includes several major new capabilities:</p>
459
460<ul>
Gabor Greifc1654ea2009-10-11 11:44:34 +0000[diff] [blame]461<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]462 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
463<li>Debug information now includes line numbers when optimizations are enabled.
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]464 This allows statistical sampling tools like OProfile and Shark to map
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]465 samples back to source lines.</li>
Gabor Greifc1654ea2009-10-11 11:44:34 +0000[diff] [blame]466<li>LLVM now includes new experimental backends to support the MSP430, SystemZ
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]467 and BlackFin architectures.</li>
468<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
469 enables support for <a href="LinkTimeOptimization.html">transparent
470 link-time optimization</a> on ELF targets when used with the Gold binutils
471 linker.</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]472<li>LLVM now supports doing optimization and code generation on multiple
473 threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
474 Programmer's Manual</a> for more information.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]475<li>LLVM now has experimental support for <a
476 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
477 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
478 final and the .bc file format may change in future releases. Debug info
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]479 does not yet use this format in LLVM 2.6.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]480</ul>
481
482</div>
483
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]484<!--=========================================================================-->
485<div class="doc_subsection">
486<a name="coreimprovements">LLVM IR and Core Improvements</a>
487</div>
488
489<div class="doc_text">
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]490<p>LLVM IR has several new features for better support of new targets and that
491expose new optimization opportunities:</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]492
493<ul>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]494<li>The <a href="LangRef.html#i_add">add</a>, <a
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]495 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]496 instructions have been split into integer and floating point versions (like
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]497 divide and remainder), introducing new <a
498 href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
499 and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
500<li>The <a href="LangRef.html#i_add">add</a>, <a
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]501 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]502 instructions now support optional "nsw" and "nuw" bits which indicate that
503 the operation is guaranteed to not overflow (in the signed or
504 unsigned case, respectively). This gives the optimizer more information and
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]505 can be used for things like C signed integer values, which are undefined on
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]506 overflow.</li>
507<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
508 optional "exact" flag which indicates that the result of the division is
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]509 guaranteed to have a remainder of zero. This is useful for optimizing pointer
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]510 subtraction in C.</li>
511<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
512 supports arbitrary integer index values for array/pointer indices. This
Benjamin Kramer08f0add2009-10-10 19:45:13 +0000[diff] [blame]513 allows for better code generation on 16-bit targets like PIC16.</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]514<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
515 supports an "inbounds" optimization hint that tells the optimizer that the
516 pointer is guaranteed to be within its allocated object.</li>
517<li>LLVM now support a series of new linkage types for global values which allow
518 for better optimization and new capabilities:
519 <ul>
520 <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
521 <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
522 semantics as the non-"odr" linkage types. The difference is that these
523 linkage types indicate that all definitions of the specified function
524 are guaranteed to have the same semantics. This allows inlining
525 templates functions in C++ but not inlining weak functions in C,
526 which previously both got the same linkage type.</li>
527 <li><a href="LangRef.html#linkage_available_externally">available_externally
528 </a> is a new linkage type that gives the optimizer visibility into the
529 definition of a function (allowing inlining and side effect analysis)
530 but that does not cause code to be generated. This allows better
531 optimization of "GNU inline" functions, extern templates, etc.</li>
532 <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
533 new linkage type (which is only useful on Mac OS X) that is used for
534 some metadata generation and other obscure things.</li>
535 </ul></li>
536<li>Finally, target-specific intrinsics can now return multiple values, which
537 is useful for modeling target operations with multiple results.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]538</ul>
539
540</div>
541
542<!--=========================================================================-->
543<div class="doc_subsection">
544<a name="optimizer">Optimizer Improvements</a>
545</div>
546
547<div class="doc_text">
548
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]549<p>In addition to a large array of minor performance tweaks and bug fixes, this
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]550release includes a few major enhancements and additions to the optimizers:</p>
551
552<ul>
553
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]554<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
555 pass has many improvements that allow it to better promote vector unions,
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]556 variables which are memset, and much more strange code that can happen to
557 do bitfield accesses to register operations. An interesting change is that
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]558 it now produces "unusual" integer sizes (like i1704) in some cases and lets
559 other optimizers clean things up.</li>
560<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
561 promotes small integer induction variables to 64-bit on 64-bit targets,
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]562 which provides a major performance boost for much numerical code. It also
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]563 promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
564 expressions (e.g. getelementptrs), as well as integers.</li>
565<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
566 redundancies of loads in simple cases.</li>
567<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
Duncan Sandsdc5bd2b2009-10-10 19:30:16 +0000[diff] [blame]568 inlining similar arrays from multiple callees into one caller.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]569<li>LLVM includes a new experimental Static Single Information (SSI)
570 construction pass.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]571</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]572
573</ul>
574
575</div>
576
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]577
578<!--=========================================================================-->
579<div class="doc_subsection">
580<a name="executionengine">Interpreter and JIT Improvements</a>
581</div>
582
583<div class="doc_text">
584
585<ul>
586<li>LLVM has a new "EngineBuilder" class which makes it more obvious how to
587 set up and configure an ExecutionEngine (a JIT or interpreter).</li>
588<li>The JIT now supports generating more than 16M of code.</li>
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]589<li>When configured with --with-oprofile, the JIT can now inform OProfile about
590 JIT'd code, allowing OProfile to get line number and function name
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]591 information for JIT'd functions.</li>
592<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
593 calling almost arbitrary external (natively compiled) functions.</li>
594<li>Clients of the JIT can now register a 'JITEventListener' object to receive
595 callbacks when the JIT emits or frees machine code. The OProfile support
596 uses this mechanism.</li>
597</ul>
598
599</div>
600
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]601<!--=========================================================================-->
602<div class="doc_subsection">
603<a name="codegen">Target Independent Code Generator Improvements</a>
604</div>
605
606<div class="doc_text">
607
608<p>We have put a significant amount of work into the code generator
609infrastructure, which allows us to implement more aggressive algorithms and make
610it run faster:</p>
611
612<ul>
613
Chris Lattner711542c2009-10-11 19:02:54 +0000[diff] [blame]614<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc as (<tt>-dA</tt>)
615 and clang as <tt>-fverbose-asm</tt> or <tt>-dA</tt>) now adds a lot of
616 useful information in comments to
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]617 the generated .s file. This information includes location information (if
618 built with <tt>-g</tt>) and loop nest information.</li>
619<li>The code generator now supports a new MachineVerifier pass which is useful
Duncan Sandsdc5bd2b2009-10-10 19:30:16 +0000[diff] [blame]620 for finding bugs in targets and codegen passes.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]621<li>The Machine LICM is now enabled by default. It hoists instructions out of
Duncan Sandsdc5bd2b2009-10-10 19:30:16 +0000[diff] [blame]622 loops (such as constant pool loads, loads from read-only stubs, vector
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]623 constant synthesization code, etc.) and is currently configured to only do
624 so when the hoisted operation can be rematerialized.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]625<li>The Machine Sinking pass is now enabled by default. This pass moves
626 side-effect free operations down the CFG so that they are executed on fewer
627 paths through a function.</li>
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]628<li>The code generator now performs "stack slot coloring" of register spills,
Chris Lattner10abb752009-10-10 19:26:21 +0000[diff] [blame]629 which allows spill slots to be reused. This leads to smaller stack frames
630 in cases where there are lots of register spills.</li>
631<li>The register allocator has many improvements to take better advantage of
632 commutable operations, various spiller peephole optimizations, and can now
633 coalesce cross-register-class copies.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]634<li>Tblgen now supports multiclass inheritance and a number of new string and
635 list operations like !(subst), !(foreach), !car, !cdr, !null, !if, !cast.
636 These make the .td files more expressive and allow more aggressive factoring
637 of duplication across instruction patterns.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]638<li>Target-specific intrinsics can now be added without having to hack VMCore to
639 add them. This makes it easier to maintain out-of-tree targets.</li>
Chris Lattner10abb752009-10-10 19:26:21 +0000[diff] [blame]640<li>The instruction selector is better at propagating information about values
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]641 (such as whether they are sign/zero extended etc.) across basic block
Chris Lattner10abb752009-10-10 19:26:21 +0000[diff] [blame]642 boundaries.</li>
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]643<li>The SelectionDAG datastructure has new nodes for representing buildvector
644 and <a href="http://llvm.org/PR2957">vector shuffle</a> operations. This
645 makes operations and pattern matching more efficient and easier to get
646 right.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]647<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
648 the "shrink wrapping" optimization, which moves spills and reloads around in
649 the CFG to avoid doing saves on paths that don't need them.</li>
650<li>LLVM includes new experimental support for writing ELF .o files directly
651 from the compiler. It works well for many simple C testcases, but doesn't
652 support exception handling, debug info, inline assembly, etc.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]653<li>Targets can now specify register allocation hints through
Gabor Greif669766d2009-10-11 10:27:57 +0000[diff] [blame]654 MachineRegisterInfo::setRegAllocationHint. A regalloc hint consists of hint
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]655 type and physical register number. A hint type of zero specifies a register
656 allocation preference. Other hint type values are target specific which are
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]657 resolved by TargetRegisterInfo::ResolveRegAllocHint. An example is the ARM
658 target which uses register hints to request that the register allocator
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]659 provide an even / odd register pair to two virtual registers.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]660</ul>
661</div>
662
663<!--=========================================================================-->
664<div class="doc_subsection">
665<a name="x86">X86-32 and X86-64 Target Improvements</a>
666</div>
667
668<div class="doc_text">
669<p>New features of the X86 target include:
670</p>
671
672<ul>
673
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]674<li>SSE 4.2 builtins are now supported.</li>
675<li>GCC-compatible soft float modes are now supported, which are typically used
676 by OS kernels.</li>
677<li>X86-64 now models implicit zero extensions better, which allows the code
678 generator to remove a lot of redundant zexts. It also models the 8-bit "H"
Duncan Sands64869652009-10-11 11:20:26 +0000[diff] [blame]679 registers as subregs, which allows them to be used in some tricky
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]680 situations.</li>
681<li>X86-64 now supports the "local exec" and "initial exec" thread local storage
682 model.</li>
683<li>The vector forms of the <a href="LangRef.html#i_icmp">icmp</a> and <a
684 href="LangRef.html#i_fcmp">fcmp</a> instructions now select to efficient
685 SSE operations.</li>
Chris Lattner2c50edb2009-10-11 18:21:32 +0000[diff] [blame]686<li>Support for the win64 calling conventions have improved. The primary
687 missing feature is support for varargs function definitions. It seems to
688 work well for many win64 JIT purposes.</li>
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]689<li>The X86 backend has preliminary support for <a
690 href="CodeGenerator.html#x86_memory">mapping address spaces to segment
691 register references</a>. This allows you to write GS or FS relative memory
692 accesses directly in LLVM IR for cases where you know exactly what you're
693 doing (such as in an OS kernel). There are some known problems with this
694 support, but it works in simple cases.</li>
695<li>The X86 code generator has been refactored to move all global variable
696 reference logic to one place
697 (<tt>X86Subtarget::ClassifyGlobalReference</tt>) which
698 makes it easier to reason about.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]699</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]700</ul>
701
702</div>
703
704<!--=========================================================================-->
705<div class="doc_subsection">
706<a name="pic16">PIC16 Target Improvements</a>
707</div>
708
709<div class="doc_text">
710<p>New features of the PIC16 target include:
711</p>
712
713<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]714<li>Support for floating-point, indirect function calls, and
715 passing/returning aggregate types to functions.
716<li>The code generator is able to generate debug info into output COFF files.
717<li>Support for placing an object into a specific section or at a specific
718 address in memory.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]719</ul>
720
721<p>Things not yet supported:</p>
722
723<ul>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]724<li>Variable arguments.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]725<li>Interrupts/programs.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]726</ul>
727
728</div>
729
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]730<!--=========================================================================-->
731<div class="doc_subsection">
732<a name="ARM">ARM Target Improvements</a>
733</div>
734
735<div class="doc_text">
736<p>New features of the ARM target include:
737</p>
738
739<ul>
740
741<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel16eac042009-08-20 15:01:16 +0000[diff] [blame]742that implement version v7-A of the ARM architecture. The ARM backend now
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]743supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.</li>
744
745<li>The AAPCS-VFP "hard float" calling conventions are also supported with the
746<tt>-float-abi=hard</tt> flag.</li>
747
Gabor Greif669766d2009-10-11 10:27:57 +0000[diff] [blame]748<li>The ARM calling convention code is now tblgen generated instead of resorting
749 to C++ code.</li>
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]750</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]751
Chris Lattnerfdf24e72009-10-10 21:40:13 +0000[diff] [blame]752
753<p>These features are still somewhat experimental
754and subject to change. The Neon intrinsics, in particular, may change in future
Chris Lattner2c50edb2009-10-11 18:21:32 +0000[diff] [blame]755releases of LLVM. ARMv7 support has progressed a lot on top of tree since 2.6
756branched.</p>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]757
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]758</ul>
759
760</div>
761
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]762<!--=========================================================================-->
763<div class="doc_subsection">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]764<a name="OtherTarget">Other Target Specific Improvements</a>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]765</div>
766
767<div class="doc_text">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]768<p>New features of other targets include:
769</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]770
771<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]772<li>Mips now supports O32 Calling Convention.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]773<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
774 support, lots of bugs fixed.</li>
775<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
776 Needs more testing.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]777</ul>
778
779</div>
780
781<!--=========================================================================-->
782<div class="doc_subsection">
783<a name="newapis">New Useful APIs</a>
784</div>
785
786<div class="doc_text">
787
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]788<p>This release includes a number of new APIs that are used internally, which
789 may also be useful for external clients.
790</p>
791
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]792<ul>
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]793<li>New <a href="http://llvm.org/doxygen/PrettyStackTrace_8h-source.html">
794 PrettyStackTrace classes</a> allows crashes of llvm tools (and applications
795 that integrate them) to provide more detailed indication of what the
796 compiler was doing at the time of the crash (e.g. running a pass).
797 At the top level for each LLVM tool, it includes the command line arguments.
798 </li>
799<li>New <a href="http://llvm.org/doxygen/StringRef_8h-source.html">StringRef</a>
800 and <a href="http://llvm.org/doxygen/Twine_8h-source.html">Twine</a> classes
801 make operations on character ranges and
802 string concatenation to be more efficient. StringRef is just a <tt>const
803 char*</tt> with a length, Twine is a light-weight rope.</li>
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]804<li>LLVM has new WeakVH, AssertingVH and CallbackVH classes, which make it
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]805 easier to write LLVM IR transformations. WeakVH is automatically drops to
806 null when the referenced Value is deleted, and is updated across a
807 replaceAllUsesWith operation. AssertingVH aborts the program if the
808 referenced value is destroyed while it is being referenced. CallbackVH is
809 a customizable class for handling value references. See <a
810 href="http://llvm.org/doxygen/ValueHandle_8h-source.html">ValueHandle.h</a>
811 for more information.</li>
812<li>The new '<a href="http://llvm.org/doxygen/Triple_8h-source.html">Triple
813 </a>' class centralizes a lot of logic that reasons about target
814 triples.</li>
Chris Lattnerb9a51552009-10-10 22:15:25 +0000[diff] [blame]815<li>The new '<a href="http://llvm.org/doxygen/ErrorHandling_8h-source.html">
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]816 llvm_report_error()</a>' set of APIs allows tools to embed the LLVM
817 optimizer and backend and recover from previously unrecoverable errors.</li>
818<li>LLVM has new abstractions for <a
819 href="http://llvm.org/doxygen/Atomic_8h-source.html">atomic operations</a>
820 and <a href="http://llvm.org/doxygen/RWMutex_8h-source.html">reader/writer
821 locks</a>.</li>
822<li>LLVM has new <a href="http://llvm.org/doxygen/SourceMgr_8h-source.html">
823 SourceMgr and SMLoc classes</a> which implement caret diagnostics and basic
824 include stack processing for simple parsers. It is used by tablegen,
825 llvm-mc, the .ll parser and FileCheck.</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]826</ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]827
828
829</div>
830
831<!--=========================================================================-->
832<div class="doc_subsection">
833<a name="otherimprovements">Other Improvements and New Features</a>
834</div>
835
836<div class="doc_text">
837<p>Other miscellaneous features include:</p>
838
839<ul>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]840<li>LLVM now includes a new internal '<a
841 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
842 writing much more accurate regression tests that run faster. Please see the
843 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
844 Guide</a> for more information.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]845<li>LLVM profile information support has been significantly improved to produce
846correct use counts, and has support for edge profiling with reduced runtime
847overhead. Combined, the generated profile information is both more correct and
848imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
849CPU2000).</li>
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]850<li>The C bindings (in the llvm/include/llvm-c directory) include many newly
851 supported APIs.</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]852<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]853 programming language.</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]854
Chris Lattner835f2532009-10-10 22:02:58 +0000[diff] [blame]855<li>The LLVMC driver has several new features:
856 <ul>
857 <li>Dynamic plugins now work on Windows.</li>
858 <li>New option property: init. Makes possible to provide default values for
859 options defined in plugins (interface to cl::init).</li>
860 <li>New example: Skeleton, shows how to create a standalone LLVMC-based
861 driver.</li>
862 <li>New example: mcc16, a driver for the PIC16 toolchain.</li>
863 </ul>
864</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]865
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]866</ul>
867
868</div>
869
870
871<!--=========================================================================-->
872<div class="doc_subsection">
873<a name="changes">Major Changes and Removed Features</a>
874</div>
875
876<div class="doc_text">
877
878<p>If you're already an LLVM user or developer with out-of-tree changes based
Owen Andersonbe3fe4e2009-07-02 16:48:38 +0000[diff] [blame]879on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]880from the previous release.</p>
881
882<ul>
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]883<li>The Itanium (IA64) backend has been removed. It was not actively supported
884 and had bitrotted.</li>
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]885<li>The BigBlock register allocator has been removed, it had also bitrotted.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]886<li>The C Backend (-march=c) is no longer considered part of the LLVM release
887criteria. We still want it to work, but no one is maintaining it and it lacks
888support for arbitrary precision integers and other important IR features.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]889
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]890<li>All LLVM tools now default to overwriting their output file, behaving more
891 like standard unix tools. Previously, this only happened with the '-f'
892 option.</li>
893<li>LLVM build now builds all libraries as .a files instead of some
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]894 libraries as relinked .o files. This requires some APIs like
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]895 InitializeAllTargets.h.
896 </li>
897</ul>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]898
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]899
900<p>In addition, many APIs have changed in this release. Some of the major LLVM
901API changes are:</p>
902
903<ul>
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]904<li>All uses of hash_set and hash_map have been removed from the LLVM tree and
905 the wrapper headers have been removed.</li>
906<li>The llvm/Streams.h and DOUT member of Debug.h have been removed. The
907 llvm::Ostream class has been completely removed and replaced with uses of
908 raw_ostream.</li>
Owen Andersonbe3fe4e2009-07-02 16:48:38 +0000[diff] [blame]909<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
910 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
911 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
912 for clients that will only ever use a single context, the new
913 <tt>getGlobalContext()</tt> API can be used to access a default global
914 context which can be passed in any and all cases where a context is
915 required.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]916<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]917<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
Gabor Greifc1654ea2009-10-11 11:44:34 +0000[diff] [blame]918 overloaded for floating-point types. Floating-point addition, subtraction
Dan Gohman79537c92009-07-07 20:05:15 +0000[diff] [blame]919 and multiplication are now represented with new operators <tt>FAdd</tt>,
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]920 <tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
921 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
Dan Gohman79537c92009-07-07 20:05:15 +0000[diff] [blame]922 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
Gabor Greif00ade922009-10-11 11:23:40 +0000[diff] [blame]923 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
Dan Gohman79537c92009-07-07 20:05:15 +0000[diff] [blame]924 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbara7d9e052009-07-12 20:41:27 +0000[diff] [blame]925<li>The DynamicLibrary class can no longer be constructed, its functionality has
926 moved to static member functions.</li>
Dan Gohmanb6b11702009-07-15 19:59:19 +0000[diff] [blame]927<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
928 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
929 <tt>false</tt>, an error will be reported if a file with the given name
930 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
931 be silently truncated (which is the behavior before this flag was
932 added).</li>
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]933<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
934longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
935used.</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]936
Daniel Dunbare3572ba2009-07-25 04:41:11 +0000[diff] [blame]937<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
938and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
939or <tt>std::string</tt>, as described in
940the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]941clients should be unaffected by this transition, unless they are used to
942<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
9432.6:
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]944 <ul>
945 <li><tt>getNameStr()</tt> is still available, and matches the old
946 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
947 although more efficient alternatives are now possible.</li>
948
949 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
950 a <tt>std::ostream</tt>, consider migrating
951 to <tt>llvm::raw_ostream</tt>.</li>
952
953 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
954 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
955 Note that this string (as before), may not be the entire name if the
Benjamin Kramer08f0add2009-10-10 19:45:13 +0000[diff] [blame]956 name contains embedded null characters.</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]957
958 <li>If you were using operator plus on the result of <tt>getName()</tt> and
959 treating the result as an <tt>std::string</tt>, you can either
Duncan Sandsd4f53352009-10-10 20:06:04 +0000[diff] [blame]960 use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]961 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbare03513b2009-07-25 23:55:21 +0000[diff] [blame]962
963 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramer7b2136d2009-08-05 15:42:44 +0000[diff] [blame]964 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]965 </ul>
966</li>
967
Daniel Dunbar48224ee2009-07-26 02:12:58 +0000[diff] [blame]968<li>The registration interfaces for backend Targets has changed (what was
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]969previously TargetMachineRegistry). For backend authors, see the <a
970href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
971guide. For clients, the notable API changes are:
Daniel Dunbarc9a70092009-07-26 05:41:39 +0000[diff] [blame]972 <ul>
973 <li><tt>TargetMachineRegistry</tt> has been renamed
974 to <tt>TargetRegistry</tt>.</li>
975
976 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
977 function to find targets.</li>
978 </ul>
979</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]980</ul>
981
982</div>
983
984
985
986<!-- *********************************************************************** -->
987<div class="doc_section">
988 <a name="portability">Portability and Supported Platforms</a>
989</div>
990<!-- *********************************************************************** -->
991
992<div class="doc_text">
993
994<p>LLVM is known to work on the following platforms:</p>
995
996<ul>
997<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]998 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
999 systems).</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1000<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]1001 and 64-bit modes.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1002<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
1003<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
1004 support is available for native builds with Visual C++).</li>
1005<li>Sun UltraSPARC workstations running Solaris 10.</li>
1006<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1007</ul>
1008
1009<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
1010to the machine and operating system on which it is built. However, minor
1011porting may be required to get LLVM to work on new platforms. We welcome your
1012portability patches and reports of successful builds or error messages.</p>
1013
1014</div>
1015
1016<!-- *********************************************************************** -->
1017<div class="doc_section">
1018 <a name="knownproblems">Known Problems</a>
1019</div>
1020<!-- *********************************************************************** -->
1021
1022<div class="doc_text">
1023
1024<p>This section contains significant known problems with the LLVM system,
1025listed by component. If you run into a problem, please check the <a
1026href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
1027there isn't already one.</p>
1028
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]1029<ul>
Chris Lattnerc8ab34d2009-10-11 19:07:23 +0000[diff] [blame]1030<li>The llvm-gcc bootstrap will fail with some versions of binutils (e.g. 2.15)
1031 with a message of "<tt><a href="http://llvm.org/PR5004">Error: can not do 8
1032 byte pc-relative relocation</a></tt>" when building C++ code. We intend to
1033 fix this on mainline, but a workaround for 2.6 is to upgrade to binutils
1034 2.17 or later.</li>
1035
Chris Lattner4050d252009-07-21 23:17:26 +0000[diff] [blame]1036<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]1037using the stock GCC 3.x.x series 'out the box',
1038See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
1039However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]1040for x86/x86-64 has been made available from the third party AuroraUX Project
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]1041that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]1042</ul>
1043
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1044</div>
1045
1046<!-- ======================================================================= -->
1047<div class="doc_subsection">
1048 <a name="experimental">Experimental features included with this release</a>
1049</div>
1050
1051<div class="doc_text">
1052
1053<p>The following components of this LLVM release are either untested, known to
1054be broken or unreliable, or are in early development. These components should
1055not be relied on, and bugs should not be filed against them, but they may be
1056useful to some people. In particular, if you would like to work on one of these
1057components, please contact us on the <a
1058href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
1059
1060<ul>
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]1061<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430 and SystemZ backends are
1062 experimental.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1063<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner8767bdc2009-10-10 22:13:38 +0000[diff] [blame]1064 supported value for this option. The ELF writer is experimental.</li>
1065<li>The implementation of Andersen's Alias Analysis has many known bugs.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1066</ul>
1067
1068</div>
1069
1070<!-- ======================================================================= -->
1071<div class="doc_subsection">
1072 <a name="x86-be">Known problems with the X86 back-end</a>
1073</div>
1074
1075<div class="doc_text">
1076
1077<ul>
1078 <li>The X86 backend does not yet support
1079 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1080 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1081 'u'.</li>
1082 <li>The X86 backend generates inefficient floating point code when configured
1083 to generate code for systems that don't have SSE2.</li>
1084 <li>Win64 code generation wasn't widely tested. Everything should work, but we
1085 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
1086 runtime currently due
1087 to <a href="http://llvm.org/PR2255">several</a>
1088 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
1089 the
1090 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
1091 <li>The X86-64 backend does not yet support the LLVM IR instruction
1092 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
1093 argument constructs on X86-64 by lowering them manually.</li>
1094</ul>
1095
1096</div>
1097
1098<!-- ======================================================================= -->
1099<div class="doc_subsection">
1100 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1101</div>
1102
1103<div class="doc_text">
1104
1105<ul>
1106<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1107compilation, and lacks support for debug information.</li>
1108</ul>
1109
1110</div>
1111
1112<!-- ======================================================================= -->
1113<div class="doc_subsection">
1114 <a name="arm-be">Known problems with the ARM back-end</a>
1115</div>
1116
1117<div class="doc_text">
1118
1119<ul>
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]1120<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
1121and not well tested. Some features may not work at all, and the code quality
1122may be poor in some cases.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1123<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
1124processors, thumb programs can crash or produce wrong
1125results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
1126<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
1127</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1128</ul>
1129
1130</div>
1131
1132<!-- ======================================================================= -->
1133<div class="doc_subsection">
1134 <a name="sparc-be">Known problems with the SPARC back-end</a>
1135</div>
1136
1137<div class="doc_text">
1138
1139<ul>
1140<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
1141 support the 64-bit SPARC ABI (-m64).</li>
1142</ul>
1143
1144</div>
1145
1146<!-- ======================================================================= -->
1147<div class="doc_subsection">
1148 <a name="mips-be">Known problems with the MIPS back-end</a>
1149</div>
1150
1151<div class="doc_text">
1152
1153<ul>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1154<li>64-bit MIPS targets are not supported yet.</li>
1155</ul>
1156
1157</div>
1158
1159<!-- ======================================================================= -->
1160<div class="doc_subsection">
1161 <a name="alpha-be">Known problems with the Alpha back-end</a>
1162</div>
1163
1164<div class="doc_text">
1165
1166<ul>
1167
1168<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1169appropriate nops inserted to ensure restartability.</li>
1170
1171</ul>
1172</div>
1173
1174<!-- ======================================================================= -->
1175<div class="doc_subsection">
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1176 <a name="c-be">Known problems with the C back-end</a>
1177</div>
1178
1179<div class="doc_text">
1180
1181<ul>
1182<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1183 inline assembly code</a>.</li>
1184<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1185 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1186 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1187<li>The C backend does not support all exception handling constructs.</li>
1188<li>The C backend does not support arbitrary precision integers.</li>
1189</ul>
1190
1191</div>
1192
1193
1194<!-- ======================================================================= -->
1195<div class="doc_subsection">
1196 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
1197</div>
1198
1199<div class="doc_text">
1200
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1201<p>The only major language feature of GCC not supported by llvm-gcc is
1202 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1203 are only supported on some targets. For example, trampolines are only
1204 supported on some targets (these are used when you take the address of a
1205 nested function).</p>
1206
1207<p>If you run into GCC extensions which are not supported, please let us know.
1208</p>
1209
1210</div>
1211
1212<!-- ======================================================================= -->
1213<div class="doc_subsection">
1214 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
1215</div>
1216
1217<div class="doc_text">
1218
1219<p>The C++ front-end is considered to be fully
1220tested and works for a number of non-trivial programs, including LLVM
1221itself, Qt, Mozilla, etc.</p>
1222
1223<ul>
1224<li>Exception handling works well on the X86 and PowerPC targets. Currently
1225 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
1226</ul>
1227
1228</div>
1229
1230<!-- ======================================================================= -->
1231<div class="doc_subsection">
1232 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1233</div>
1234
1235<div class="doc_text">
1236<ul>
1237<li>Fortran support generally works, but there are still several unresolved bugs
Gabor Greif25d75362009-10-11 10:44:44 +0000[diff] [blame]1238 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1239 tools/gfortran component for details.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1240</ul>
1241</div>
1242
1243<!-- ======================================================================= -->
1244<div class="doc_subsection">
1245 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1246</div>
1247
1248<div class="doc_text">
1249The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1250technology, and problems should be expected.
1251<ul>
1252<li>The Ada front-end currently only builds on X86-32. This is mainly due
1253to lack of trampoline support (pointers to nested functions) on other platforms.
1254However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1255which does support trampolines.</li>
1256<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1257This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1258exception handling, which is used internally by the compiler.
1259Workaround: configure with --disable-bootstrap.</li>
1260<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1261and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1262(c380004 also fails with gcc-4.2 mainline).
1263If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1264causes the compiler to go into an infinite loop, using up all system memory.</li>
1265<li>Some GCC specific Ada tests continue to crash the compiler.</li>
1266<li>The -E binder option (exception backtraces)
1267<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1268crashing if an exception is raised. Workaround: do not use -E.</li>
1269<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1270or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1271or use representation clauses that result in a field of a non-discrete type
1272starting or finishing in the middle of a byte.</li>
1273<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1274'main' as generated by the Ada binder to be invalid</a>.
1275Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1276<tt>envp</tt> rather than integers.</li>
1277<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1278ignored</a>.</li>
1279</ul>
1280</div>
1281
Erick Tryzelaarb4cf9752009-09-28 04:42:55 +0000[diff] [blame]1282<!-- ======================================================================= -->
1283<div class="doc_subsection">
1284 <a name="ocaml-bindingse">Known problems with the O'Caml bindings</a>
1285</div>
1286
1287<div class="doc_text">
1288
1289<p>The Llvm.Linkage module is broken, and has incorrect values. Only
1290Llvm.Linkage.External, Llvm.Linkage.Available_externally, and
1291Llvm.Linkage.Link_once will be correct. If you need any of the other linkage
1292modes, you'll have to write an external C library in order to expose the
1293functionality. This has been fixed in the trunk.</p>
1294</div>
1295
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1296<!-- *********************************************************************** -->
1297<div class="doc_section">
1298 <a name="additionalinfo">Additional Information</a>
1299</div>
1300<!-- *********************************************************************** -->
1301
1302<div class="doc_text">
1303
1304<p>A wide variety of additional information is available on the <a
1305href="http://llvm.org">LLVM web page</a>, in particular in the <a
1306href="http://llvm.org/docs/">documentation</a> section. The web page also
1307contains versions of the API documentation which is up-to-date with the
1308Subversion version of the source code.
1309You can access versions of these documents specific to this release by going
1310into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1311
1312<p>If you have any questions or comments about LLVM, please feel free to contact
1313us via the <a href="http://llvm.org/docs/#maillist"> mailing
1314lists</a>.</p>
1315
1316</div>
1317
1318<!-- *********************************************************************** -->
1319
1320<hr>
1321<address>
1322 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1323 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
1324 <a href="http://validator.w3.org/check/referer"><img
1325 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
1326
1327 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
1328 Last modified: $Date$
1329</address>
1330
1331</body>
1332</html>