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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 7c3418ba580ca096963b36ba30c3a1deebb6ca80 / . / docs / ReleaseNotes.html
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4<head>
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Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]7 <title>LLVM 2.6 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]10
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]11<div class="doc_title">LLVM 2.6 Release Notes</div>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]12
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]13<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]14 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]15 <li><a href="#subproj">Sub-project Status Update</a></li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]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>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]18 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#portability">Portability and Supported Platforms</a></li>
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]20 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]21 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]22</ol>
23
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]24<div class="doc_author">
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]25 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]26</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]27
28<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]29<div class="doc_section">
30 <a name="intro">Introduction</a>
31</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]32<!-- *********************************************************************** -->
33
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]34<div class="doc_text">
35
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]36<p>This document contains the release notes for the LLVM Compiler
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]37Infrastructure, release 2.6. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]38major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]39All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]40href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]41
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]42<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]43release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]44web site</a>. If you have questions or comments, the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
46List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]47
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]48<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]49main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +0000[diff] [blame]50current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]51<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]52
53</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]54
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]55
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]56<!--
57Almost dead code.
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 Lattner76ef2982010-01-09 22:30:40 +0000[diff] [blame]61 ABCD, SCCVN, GEPSplitterPass
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]62-->
63
64
65<!-- Unfinished features in 2.6:
66 gcc plugin.
67 strong phi elim
68 variable debug info for optimized code
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]69 postalloc scheduler: anti dependence breaking, hazard recognizer?
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]70 metadata
71 loop dependence analysis
72 ELF Writer? How stable?
73 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
74 2.7 supports the GDB 7.0 jit interfaces for debug info.
75 2.7 eliminates ADT/iterator.h
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]76 -->
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]77
Chris Lattner547a3912008-10-12 19:47:48 +0000[diff] [blame]78 <!-- for announcement email:
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]79 Logo web page.
80 llvm devmtg
81 compiler_rt
82 KLEE web page at klee.llvm.org
83 Many new papers added to /pubs/
84 Mention gcc plugin.
85
Chris Lattner74c80df2009-02-25 06:34:50 +0000[diff] [blame]86 -->
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]87
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]88<!-- *********************************************************************** -->
89<div class="doc_section">
90 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]91</div>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]92<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]93
94<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]95<p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]96The LLVM 2.6 distribution currently consists of code from the core LLVM
97repository (which roughly includes the LLVM optimizers, code generators
98and supporting tools), the Clang repository and the llvm-gcc repository. In
99addition to this code, the LLVM Project includes other sub-projects that are in
100development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +0000[diff] [blame]101</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]102
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]103</div>
104
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]105
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]106<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]107<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]108<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]109</div>
110
111<div class="doc_text">
112
113<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]114a set of new 'LLVM native' front-end technologies for the C family of languages.
115LLVM 2.6 is the first release to officially include Clang, and it provides a
116production quality C and Objective-C compiler. If you are interested in <a
117href="http://clang.llvm.org/performance.html">fast compiles</a> and
118<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
119encourage you to try it out. Clang currently compiles typical Objective-C code
1203x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
121(which is when the most pressure is on the frontend).</p>
122
123<p>In addition to supporting these languages, C++ support is also <a
124href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
125Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
126If you are interested in Clang C++ support or any other Clang feature, we
127strongly encourage you to get involved on the <a
Chris Lattnerf40c40b2009-02-25 05:09:54 +0000[diff] [blame]128href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
129list</a>.</p>
130
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]131<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000[diff] [blame]132
Daniel Dunbar13739432008-10-14 23:25:09 +0000[diff] [blame]133<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]134<li>C and Objective-C support are now considered production quality.</li>
135<li>AuroraUX, FreeBSD and OpenBSD are now supported.</li>
136<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
137<li>Many many bugs are fixed and lots of features have been added.</li>
Bill Wendling6bc15282009-03-02 04:28:18 +0000[diff] [blame]138</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]139</div>
140
141<!--=========================================================================-->
142<div class="doc_subsection">
143<a name="clangsa">Clang Static Analyzer</a>
144</div>
145
146<div class="doc_text">
147
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]148<p>Previously announced in the 2.4 and 2.5 LLVM releases, the Clang project also
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]149includes an early stage static source code analysis tool for <a
150href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]151in C and Objective-C programs. The tool performs checks to find
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]152bugs that occur on a specific path within a program.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]153
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]154<p>In the LLVM 2.6 time-frame, the analyzer core has undergone several important
155improvements and cleanups and now includes a new <em>Checker</em> interface that
156is intended to eventually serve as a basis for domain-specific checks. Further,
157in addition to generating HTML files for reporting analysis results, the
158analyzer can now also emit bug reports in a structured XML format that is
159intended to be easily readable by other programs.</p>
Ted Kremenek3c3ec0c2008-10-14 05:14:21 +0000[diff] [blame]160
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]161<p>The set of checks performed by the static analyzer continues to expand, and
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]162future plans for the tool include full source-level inter-procedural analysis
163and deeper checks such as buffer overrun detection. There are many opportunities
164to extend and enhance the static analyzer, and anyone interested in working on
165this project is encouraged to get involved!</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]166
167</div>
168
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]169<!--=========================================================================-->
170<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]171<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]172</div>
173
174<div class="doc_text">
175<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]176The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]177a JVM and a CLI Virtual Machine (Microsoft .NET is an
178implementation of the CLI) using LLVM for static and just-in-time
179compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]180
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]181<p>
182VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
183<a href="http://vmkit.llvm.org/releases/">web page</a>. The release includes
Nicolas Geoffray56d313d2008-10-15 20:25:04 +0000[diff] [blame]184bug fixes, cleanup and new features. The major changes are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]185
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]186<ul>
187
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]188<li>A new llcj tool to generate shared libraries or executables of Java
189 files.</li>
190<li>Cooperative garbage collection. </li>
191<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
192<li>Implementation of a two-word header for Java objects instead of the original
193 three-word header. </li>
194<li>Better Java specification-compliance: division by zero checks, stack
195 overflow checks, finalization and references support. </li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]196
197</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]198</div>
199
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]200
201<!--=========================================================================-->
202<div class="doc_subsection">
203<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
204</div>
205
206<div class="doc_text">
207<p>
208The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
209is a simple library that provides an implementation of the low-level
210target-specific hooks required by code generation and other runtime components.
211For example, when compiling for a 32-bit target, converting a double to a 64-bit
212unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
213function. The compiler-rt library provides highly optimized implementations of
214this and other low-level routines (some are 3x faster than the equivalent
215libgcc routines).</p>
216
217<p>
218All of the code in the compiler-rt project is available under the standard LLVM
219License, a "BSD-style" license.</p>
220
221</div>
222
223<!--=========================================================================-->
224<div class="doc_subsection">
225<a name="klee">KLEE: Symbolic Execution and Automatic Test Case Generator</a>
226</div>
227
228<div class="doc_text">
229<p>
230The new LLVM <a href="http://klee.llvm.org/">KLEE project</a> is a symbolic
231execution framework for programs in LLVM bitcode form. KLEE tries to
232symbolically evaluate "all" paths through the application and records state
233transitions that lead to fault states. This allows it to construct testcases
234that lead to faults and can even be used to verify algorithms. For more
235details, please see the <a
236href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
237KLEE.</p>
238
239</div>
240
241<!--=========================================================================-->
242<div class="doc_subsection">
243<a name="dragonegg">DragonEgg: GCC-4.5 as an LLVM frontend</a>
244</div>
245
246<div class="doc_text">
247<p>
248The goal of <a href="http://dragonegg.llvm.org/">DragonEgg</a> is to make
249gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever.
Duncan Sands78a1dcc2009-10-15 08:17:44 +0000[diff] [blame]250<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a shared library (dragonegg.so)
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]251that is loaded by gcc at runtime. It uses the new gcc plugin architecture to
252disable the GCC optimizers and code generators, and schedule the LLVM optimizers
253and code generators (or direct output of LLVM IR) instead. Currently only Linux
254and Darwin are supported, and only on x86-32 and x86-64. It should be easy to
255add additional unix-like architectures and other processor families. In theory
256it should be possible to use <a href="http://dragonegg.llvm.org/">DragonEgg</a>
257with any language supported by gcc, however only C and Fortran work well for the
258moment. Ada and C++ work to some extent, while Java, Obj-C and Obj-C++ are so
259far entirely untested. Since gcc-4.5 has not yet been released, neither has
260<a href="http://dragonegg.llvm.org/">DragonEgg</a>. To build
261<a href="http://dragonegg.llvm.org/">DragonEgg</a> you will need to check out the
262development versions of <a href="http://gcc.gnu.org/svn.html/"> gcc</a>,
263<a href="http://llvm.org/docs/GettingStarted.html#checkout">llvm</a> and
264<a href="http://dragonegg.llvm.org/">DragonEgg</a> from their respective
265subversion repositories, and follow the instructions in the
266<a href="http://dragonegg.llvm.org/">DragonEgg</a> README.
267</p>
268
269</div>
270
271
272<!--=========================================================================-->
273<div class="doc_subsection">
274<a name="mc">llvm-mc: Machine Code Toolkit</a>
275</div>
276
277<div class="doc_text">
278<p>
279The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
280better tools for dealing with machine code, object file formats, etc. The idea
281is to be able to generate most of the target specific details of assemblers and
282disassemblers from existing LLVM target .td files (with suitable enhancements),
283and to build infrastructure for reading and writing common object file formats.
284One of the first deliverables is to build a full assembler and integrate it into
285the compiler, which is predicted to substantially reduce compile time in some
286scenarios.
287</p>
288
289<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
290can reliably parse and pretty print (with some encoding information) a
291darwin/x86 .s file successfully, and has the very early phases of a Mach-O
292assembler in progress. Beyond the MC framework itself, major refactoring of the
293LLVM code generator has started. The idea is to make the code generator reason
294about the code it is producing in a much more semantic way, rather than a
295textual way. For example, the code generator now uses MCSection objects to
296represent section assignments, instead of text strings that print to .section
297directives.</p>
298
299<p>MC is an early and ongoing project that will hopefully continue to lead to
300many improvements in the code generator and build infrastructure useful for many
301other situations.
302</p>
303
304</div>
305
306
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]307<!-- *********************************************************************** -->
308<div class="doc_section">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]309 <a name="externalproj">External Open Source Projects Using LLVM 2.6</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]310</div>
311<!-- *********************************************************************** -->
312
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]313<div class="doc_text">
314
315<p>An exciting aspect of LLVM is that it is used as an enabling technology for
316 a lot of other language and tools projects. This section lists some of the
317 projects that have already been updated to work with LLVM 2.6.</p>
318</div>
319
320
321<!--=========================================================================-->
322<div class="doc_subsection">
323<a name="Rubinius">Rubinius</a>
324</div>
325
326<div class="doc_text">
327<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
328for running Ruby code which strives to write as much of the core class
329implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
330uses LLVM to optimize and compile ruby code down to machine code. Techniques
331such as type feedback, method inlining, and uncommon traps are all used to
332remove dynamism from ruby execution and increase performance.</p>
333
334<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
335a counter based JIT, type feedback and speculative method inlining.
336</p>
337
338</div>
339
340<!--=========================================================================-->
341<div class="doc_subsection">
342<a name="macruby">MacRuby</a>
343</div>
344
345<div class="doc_text">
346
347<p>
348<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
349core Mac OS X technologies, such as the Objective-C common runtime and garbage
350collector and the CoreFoundation framework. It is principally developed by
351Apple and aims at enabling the creation of full-fledged Mac OS X applications.
352</p>
353
354<p>
355MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
356expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
357handling.</p>
358
359</div>
360
361
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]362<!--=========================================================================-->
363<div class="doc_subsection">
364<a name="pure">Pure</a>
365</div>
366
367<div class="doc_text">
368<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]369<a href="http://pure-lang.googlecode.com/">Pure</a>
370is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]371Programs are collections of equations which are used to evaluate expressions in
372a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]373lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]374built-in list and matrix support (including list and matrix comprehensions) and
375an easy-to-use C interface. The interpreter uses LLVM as a backend to
376 JIT-compile Pure programs to fast native code.</p>
377
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]378<p>Pure versions 0.31 and later have been tested and are known to work with
379LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]380</p>
381</div>
382
383
384<!--=========================================================================-->
385<div class="doc_subsection">
386<a name="ldc">LLVM D Compiler</a>
387</div>
388
389<div class="doc_text">
390<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]391<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
392the D Programming Language using the LLVM optimizer and code generator.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]393The LDC project works great with the LLVM 2.6 release. General improvements in
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]394this
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]395cycle have included new inline asm constraint handling, better debug info
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]396support, general bug fixes and better x86-64 support. This has allowed
397some major improvements in LDC, getting it much closer to being as
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]398fully featured as the original DMD compiler from DigitalMars.
399</p>
400</div>
401
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]402<!--=========================================================================-->
403<div class="doc_subsection">
404<a name="RoadsendPHP">Roadsend PHP</a>
405</div>
406
407<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]408<p>
409<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]410source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]411language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]412reimplementation of an earlier project that is now based on LLVM.</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]413</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]414
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]415<!--=========================================================================-->
416<div class="doc_subsection">
417<a name="UnladenSwallow">Unladen Swallow</a>
418</div>
419
420<div class="doc_text">
421<p>
422<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
423branch of <a href="http://python.org/">Python</a> intended to be fully
424compatible and significantly faster. It uses LLVM's optimization passes and JIT
425compiler.</p>
426</div>
427
428<!--=========================================================================-->
429<div class="doc_subsection">
430<a name="llvm-lua">llvm-lua</a>
431</div>
432
433<div class="doc_text">
434<p>
435<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
436and static compiling support to the Lua VM. Lua bytecode is analyzed to
437remove type checks, then LLVM is used to compile the bytecode down to machine
438code.</p>
439</div>
440
441<!--=========================================================================-->
442<div class="doc_subsection">
443<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
444</div>
445
446<div class="doc_text">
447<p>
448<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
449harness to build OpenJDK using only free software build tools and to provide
450replacements for the not-yet free parts of OpenJDK. One of the extensions that
451IcedTea provides is a new JIT compiler named <a
452href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
453to provide native code generation without introducing processor-dependent
454code.
455</p>
456</div>
457
458
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]459
460<!-- *********************************************************************** -->
461<div class="doc_section">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]462 <a name="whatsnew">What's New in LLVM 2.6?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]463</div>
464<!-- *********************************************************************** -->
465
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]466<div class="doc_text">
467
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]468<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]469minor improvements. Some of the major improvements and new features are listed
470in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]471</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]472
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]473</div>
474
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]475<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]476<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]477<a name="majorfeatures">Major New Features</a>
478</div>
479
480<div class="doc_text">
481
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]482<p>LLVM 2.6 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]483
484<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]485<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>
486 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
487<li>Debug information now includes line numbers when optimizations are enabled.
488 This allows statistical sampling tools like OProfile and Shark to map
489 samples back to source lines.</li>
490<li>LLVM now includes new experimental backends to support the MSP430, SystemZ
491 and BlackFin architectures.</li>
492<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
493 enables support for <a href="LinkTimeOptimization.html">transparent
494 link-time optimization</a> on ELF targets when used with the Gold binutils
495 linker.</li>
496<li>LLVM now supports doing optimization and code generation on multiple
497 threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
498 Programmer's Manual</a> for more information.</li>
499<li>LLVM now has experimental support for <a
500 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
501 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
502 final and the .bc file format may change in future releases. Debug info
503 does not yet use this format in LLVM 2.6.</li>
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]504</ul>
505
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]506</div>
507
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]508<!--=========================================================================-->
509<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]510<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]511</div>
512
513<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]514<p>LLVM IR has several new features for better support of new targets and that
515expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]516
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]517<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]518<li>The <a href="LangRef.html#i_add">add</a>, <a
519 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
520 instructions have been split into integer and floating point versions (like
521 divide and remainder), introducing new <a
522 href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
523 and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
524<li>The <a href="LangRef.html#i_add">add</a>, <a
525 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
526 instructions now support optional "nsw" and "nuw" bits which indicate that
527 the operation is guaranteed to not overflow (in the signed or
528 unsigned case, respectively). This gives the optimizer more information and
529 can be used for things like C signed integer values, which are undefined on
530 overflow.</li>
531<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
532 optional "exact" flag which indicates that the result of the division is
533 guaranteed to have a remainder of zero. This is useful for optimizing pointer
534 subtraction in C.</li>
535<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
536 supports arbitrary integer index values for array/pointer indices. This
537 allows for better code generation on 16-bit pointer targets like PIC16.</li>
538<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
539 supports an "inbounds" optimization hint that tells the optimizer that the
540 pointer is guaranteed to be within its allocated object.</li>
541<li>LLVM now support a series of new linkage types for global values which allow
542 for better optimization and new capabilities:
543 <ul>
544 <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
545 <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
546 semantics as the non-"odr" linkage types. The difference is that these
547 linkage types indicate that all definitions of the specified function
548 are guaranteed to have the same semantics. This allows inlining
549 templates functions in C++ but not inlining weak functions in C,
550 which previously both got the same linkage type.</li>
551 <li><a href="LangRef.html#linkage_available_externally">available_externally
552 </a> is a new linkage type that gives the optimizer visibility into the
553 definition of a function (allowing inlining and side effect analysis)
554 but that does not cause code to be generated. This allows better
555 optimization of "GNU inline" functions, extern templates, etc.</li>
556 <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
557 new linkage type (which is only useful on Mac OS X) that is used for
558 some metadata generation and other obscure things.</li>
559 </ul></li>
560<li>Finally, target-specific intrinsics can now return multiple values, which
561 is useful for modeling target operations with multiple results.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]562</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]563
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]564</div>
565
566<!--=========================================================================-->
567<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]568<a name="optimizer">Optimizer Improvements</a>
569</div>
570
571<div class="doc_text">
572
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]573<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]574release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]575
576<ul>
577
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]578<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
579 pass has many improvements that allow it to better promote vector unions,
580 variables which are memset, and much more strange code that can happen to
581 do bitfield accesses to register operations. An interesting change is that
582 it now produces "unusual" integer sizes (like i1704) in some cases and lets
583 other optimizers clean things up.</li>
584<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
585 promotes small integer induction variables to 64-bit on 64-bit targets,
586 which provides a major performance boost for much numerical code. It also
587 promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
588 expressions (e.g. getelementptrs), as well as integers.</li>
589<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
590 redundancies of loads in simple cases.</li>
591<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
592 inlining similar arrays from multiple callees into one caller.</li>
593<li>LLVM includes a new experimental Static Single Information (SSI)
594 construction pass.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]595
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]596</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]597
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]598</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]599
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]600
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]601<!--=========================================================================-->
602<div class="doc_subsection">
603<a name="executionengine">Interpreter and JIT Improvements</a>
604</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]605
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]606<div class="doc_text">
607
608<ul>
609<li>LLVM has a new "EngineBuilder" class which makes it more obvious how to
610 set up and configure an ExecutionEngine (a JIT or interpreter).</li>
611<li>The JIT now supports generating more than 16M of code.</li>
612<li>When configured with <tt>--with-oprofile</tt>, the JIT can now inform
613 OProfile about JIT'd code, allowing OProfile to get line number and function
614 name information for JIT'd functions.</li>
615<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
616 calling almost arbitrary external (natively compiled) functions.</li>
617<li>Clients of the JIT can now register a 'JITEventListener' object to receive
618 callbacks when the JIT emits or frees machine code. The OProfile support
619 uses this mechanism.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]620</ul>
621
622</div>
623
624<!--=========================================================================-->
625<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]626<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]627</div>
628
629<div class="doc_text">
630
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]631<p>We have put a significant amount of work into the code generator
632infrastructure, which allows us to implement more aggressive algorithms and make
633it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]634
635<ul>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]636
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]637<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc as <tt>-dA</tt>
638 and clang as <tt>-fverbose-asm</tt> or <tt>-dA</tt>) now adds a lot of
639 useful information in comments to
640 the generated .s file. This information includes location information (if
641 built with <tt>-g</tt>) and loop nest information.</li>
642<li>The code generator now supports a new MachineVerifier pass which is useful
643 for finding bugs in targets and codegen passes.</li>
644<li>The Machine LICM is now enabled by default. It hoists instructions out of
645 loops (such as constant pool loads, loads from read-only stubs, vector
646 constant synthesization code, etc.) and is currently configured to only do
647 so when the hoisted operation can be rematerialized.</li>
648<li>The Machine Sinking pass is now enabled by default. This pass moves
649 side-effect free operations down the CFG so that they are executed on fewer
650 paths through a function.</li>
651<li>The code generator now performs "stack slot coloring" of register spills,
652 which allows spill slots to be reused. This leads to smaller stack frames
653 in cases where there are lots of register spills.</li>
654<li>The register allocator has many improvements to take better advantage of
655 commutable operations, various spiller peephole optimizations, and can now
656 coalesce cross-register-class copies.</li>
657<li>Tblgen now supports multiclass inheritance and a number of new string and
658 list operations like <tt>!(subst)</tt>, <tt>!(foreach)</tt>, <tt>!car</tt>,
659 <tt>!cdr</tt>, <tt>!null</tt>, <tt>!if</tt>, <tt>!cast</tt>.
660 These make the .td files more expressive and allow more aggressive factoring
661 of duplication across instruction patterns.</li>
662<li>Target-specific intrinsics can now be added without having to hack VMCore to
663 add them. This makes it easier to maintain out-of-tree targets.</li>
664<li>The instruction selector is better at propagating information about values
665 (such as whether they are sign/zero extended etc.) across basic block
666 boundaries.</li>
667<li>The SelectionDAG datastructure has new nodes for representing buildvector
668 and <a href="http://llvm.org/PR2957">vector shuffle</a> operations. This
669 makes operations and pattern matching more efficient and easier to get
670 right.</li>
671<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
672 the "shrink wrapping" optimization, which moves spills and reloads around in
673 the CFG to avoid doing saves on paths that don't need them.</li>
674<li>LLVM includes new experimental support for writing ELF .o files directly
675 from the compiler. It works well for many simple C testcases, but doesn't
676 support exception handling, debug info, inline assembly, etc.</li>
677<li>Targets can now specify register allocation hints through
678 <tt>MachineRegisterInfo::setRegAllocationHint</tt>. A regalloc hint consists
679 of hint type and physical register number. A hint type of zero specifies a
680 register allocation preference. Other hint type values are target specific
681 which are resolved by <tt>TargetRegisterInfo::ResolveRegAllocHint</tt>. An
682 example is the ARM target which uses register hints to request that the
683 register allocator provide an even / odd register pair to two virtual
684 registers.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]685</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]686</div>
687
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]688<!--=========================================================================-->
689<div class="doc_subsection">
690<a name="x86">X86-32 and X86-64 Target Improvements</a>
691</div>
692
693<div class="doc_text">
694<p>New features of the X86 target include:
695</p>
696
697<ul>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]698
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]699<li>SSE 4.2 builtins are now supported.</li>
700<li>GCC-compatible soft float modes are now supported, which are typically used
701 by OS kernels.</li>
702<li>X86-64 now models implicit zero extensions better, which allows the code
703 generator to remove a lot of redundant zexts. It also models the 8-bit "H"
704 registers as subregs, which allows them to be used in some tricky
705 situations.</li>
706<li>X86-64 now supports the "local exec" and "initial exec" thread local storage
707 model.</li>
708<li>The vector forms of the <a href="LangRef.html#i_icmp">icmp</a> and <a
709 href="LangRef.html#i_fcmp">fcmp</a> instructions now select to efficient
710 SSE operations.</li>
711<li>Support for the win64 calling conventions have improved. The primary
712 missing feature is support for varargs function definitions. It seems to
713 work well for many win64 JIT purposes.</li>
714<li>The X86 backend has preliminary support for <a
715 href="CodeGenerator.html#x86_memory">mapping address spaces to segment
716 register references</a>. This allows you to write GS or FS relative memory
717 accesses directly in LLVM IR for cases where you know exactly what you're
718 doing (such as in an OS kernel). There are some known problems with this
719 support, but it works in simple cases.</li>
720<li>The X86 code generator has been refactored to move all global variable
721 reference logic to one place
722 (<tt>X86Subtarget::ClassifyGlobalReference</tt>) which
723 makes it easier to reason about.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]724
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]725</ul>
726
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]727</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]728
729<!--=========================================================================-->
730<div class="doc_subsection">
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]731<a name="pic16">PIC16 Target Improvements</a>
732</div>
733
734<div class="doc_text">
735<p>New features of the PIC16 target include:
736</p>
737
738<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]739<li>Support for floating-point, indirect function calls, and
740 passing/returning aggregate types to functions.
741<li>The code generator is able to generate debug info into output COFF files.
742<li>Support for placing an object into a specific section or at a specific
743 address in memory.</li>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]744</ul>
745
746<p>Things not yet supported:</p>
747
748<ul>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]749<li>Variable arguments.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]750<li>Interrupts/programs.</li>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]751</ul>
752
753</div>
754
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]755<!--=========================================================================-->
756<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]757<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]758</div>
759
760<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]761<p>New features of the ARM target include:
762</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]763
764<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]765
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]766<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
767that implement version v7-A of the ARM architecture. The ARM backend now
768supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]769
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]770<li>The AAPCS-VFP "hard float" calling conventions are also supported with the
771<tt>-float-abi=hard</tt> flag.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]772
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]773<li>The ARM calling convention code is now tblgen generated instead of resorting
774 to C++ code.</li>
775</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]776
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]777<p>These features are still somewhat experimental
778and subject to change. The Neon intrinsics, in particular, may change in future
779releases of LLVM. ARMv7 support has progressed a lot on top of tree since 2.6
780branched.</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]781
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]782
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]783</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]784
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]785<!--=========================================================================-->
786<div class="doc_subsection">
787<a name="OtherTarget">Other Target Specific Improvements</a>
788</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]789
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]790<div class="doc_text">
791<p>New features of other targets include:
792</p>
793
794<ul>
795<li>Mips now supports O32 Calling Convention.</li>
796<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
797 support, lots of bugs fixed.</li>
798<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
799 Needs more testing.</li>
800</ul>
801
802</div>
803
804<!--=========================================================================-->
805<div class="doc_subsection">
806<a name="newapis">New Useful APIs</a>
807</div>
808
809<div class="doc_text">
810
811<p>This release includes a number of new APIs that are used internally, which
812 may also be useful for external clients.
813</p>
814
815<ul>
816<li>New <a href="http://llvm.org/doxygen/PrettyStackTrace_8h-source.html">
817 <tt>PrettyStackTrace</tt> class</a> allows crashes of llvm tools (and applications
818 that integrate them) to provide more detailed indication of what the
819 compiler was doing at the time of the crash (e.g. running a pass).
820 At the top level for each LLVM tool, it includes the command line arguments.
821 </li>
822<li>New <a href="http://llvm.org/doxygen/StringRef_8h-source.html">StringRef</a>
823 and <a href="http://llvm.org/doxygen/Twine_8h-source.html">Twine</a> classes
824 make operations on character ranges and
825 string concatenation to be more efficient. <tt>StringRef</tt> is just a <tt>const
826 char*</tt> with a length, <tt>Twine</tt> is a light-weight rope.</li>
827<li>LLVM has new <tt>WeakVH</tt>, <tt>AssertingVH</tt> and <tt>CallbackVH</tt>
828 classes, which make it easier to write LLVM IR transformations. <tt>WeakVH</tt>
829 is automatically drops to null when the referenced <tt>Value</tt> is deleted,
830 and is updated across a <tt>replaceAllUsesWith</tt> operation.
831 <tt>AssertingVH</tt> aborts the program if the
832 referenced value is destroyed while it is being referenced. <tt>CallbackVH</tt>
833 is a customizable class for handling value references. See <a
834 href="http://llvm.org/doxygen/ValueHandle_8h-source.html">ValueHandle.h</a>
835 for more information.</li>
836<li>The new '<a href="http://llvm.org/doxygen/Triple_8h-source.html">Triple
837 </a>' class centralizes a lot of logic that reasons about target
838 triples.</li>
839<li>The new '<a href="http://llvm.org/doxygen/ErrorHandling_8h-source.html">
840 llvm_report_error()</a>' set of APIs allows tools to embed the LLVM
841 optimizer and backend and recover from previously unrecoverable errors.</li>
842<li>LLVM has new abstractions for <a
843 href="http://llvm.org/doxygen/Atomic_8h-source.html">atomic operations</a>
844 and <a href="http://llvm.org/doxygen/RWMutex_8h-source.html">reader/writer
845 locks</a>.</li>
846<li>LLVM has new <a href="http://llvm.org/doxygen/SourceMgr_8h-source.html">
847 <tt>SourceMgr</tt> and <tt>SMLoc</tt> classes</a> which implement caret
848 diagnostics and basic include stack processing for simple parsers. It is
849 used by tablegen, llvm-mc, the .ll parser and FileCheck.</li>
850</ul>
851
852
853</div>
854
855<!--=========================================================================-->
856<div class="doc_subsection">
857<a name="otherimprovements">Other Improvements and New Features</a>
858</div>
859
860<div class="doc_text">
861<p>Other miscellaneous features include:</p>
862
863<ul>
864<li>LLVM now includes a new internal '<a
865 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
866 writing much more accurate regression tests that run faster. Please see the
867 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
868 Guide</a> for more information.</li>
869<li>LLVM profile information support has been significantly improved to produce
870correct use counts, and has support for edge profiling with reduced runtime
871overhead. Combined, the generated profile information is both more correct and
872imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
873CPU2000).</li>
874<li>The C bindings (in the llvm/include/llvm-c directory) include many newly
875 supported APIs.</li>
876<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
877 programming language.</li>
878
879<li>The LLVMC driver has several new features:
880 <ul>
881 <li>Dynamic plugins now work on Windows.</li>
882 <li>New option property: init. Makes possible to provide default values for
883 options defined in plugins (interface to <tt>cl::init</tt>).</li>
884 <li>New example: Skeleton, shows how to create a standalone LLVMC-based
885 driver.</li>
886 <li>New example: mcc16, a driver for the PIC16 toolchain.</li>
887 </ul>
888</li>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]889
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]890</ul>
891
892</div>
893
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]894
895<!--=========================================================================-->
896<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]897<a name="changes">Major Changes and Removed Features</a>
898</div>
899
900<div class="doc_text">
901
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]902<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]903on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]904from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]905
906<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]907<li>The Itanium (IA64) backend has been removed. It was not actively supported
908 and had bitrotted.</li>
909<li>The BigBlock register allocator has been removed, it had also bitrotted.</li>
910<li>The C Backend (<tt>-march=c</tt>) is no longer considered part of the LLVM release
911criteria. We still want it to work, but no one is maintaining it and it lacks
912support for arbitrary precision integers and other important IR features.</li>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]913
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]914<li>All LLVM tools now default to overwriting their output file, behaving more
915 like standard unix tools. Previously, this only happened with the '<tt>-f</tt>'
916 option.</li>
917<li>LLVM build now builds all libraries as .a files instead of some
918 libraries as relinked .o files. This requires some APIs like
919 InitializeAllTargets.h.
920 </li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]921</ul>
922
923
924<p>In addition, many APIs have changed in this release. Some of the major LLVM
925API changes are:</p>
926
927<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]928<li>All uses of <tt>hash_set</tt> and <tt>hash_map</tt> have been removed from
929 the LLVM tree and the wrapper headers have been removed.</li>
930<li>The llvm/Streams.h and <tt>DOUT</tt> member of Debug.h have been removed. The
931 <tt>llvm::Ostream</tt> class has been completely removed and replaced with
932 uses of <tt>raw_ostream</tt>.</li>
933<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
934 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
935 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
936 for clients that will only ever use a single context, the new
937 <tt>getGlobalContext()</tt> API can be used to access a default global
938 context which can be passed in any and all cases where a context is
939 required.
940<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
941<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
942 overloaded for floating-point types. Floating-point addition, subtraction
943 and multiplication are now represented with new operators <tt>FAdd</tt>,
944 <tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
945 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
946 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
947 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
948 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
949<li>The <tt>DynamicLibrary</tt> class can no longer be constructed, its functionality has
950 moved to static member functions.</li>
951<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
952 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
953 <tt>false</tt>, an error will be reported if a file with the given name
954 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
955 be silently truncated (which is the behavior before this flag was
956 added).</li>
957<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
958 longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt>
959 should be used.</li>
960
961<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
962and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
963or <tt>std::string</tt>, as described in
964the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
965clients should be unaffected by this transition, unless they are used to
966<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
9672.6:
968 <ul>
969 <li><tt>getNameStr()</tt> is still available, and matches the old
970 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
971 although more efficient alternatives are now possible.</li>
972
973 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
974 a <tt>std::ostream</tt>, consider migrating
975 to <tt>llvm::raw_ostream</tt>.</li>
976
977 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
978 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
979 Note that this string (as before), may not be the entire name if the
980 name contains embedded null characters.</li>
981
982 <li>If you were using <tt>operator +</tt> on the result of <tt>getName()</tt> and
983 treating the result as an <tt>std::string</tt>, you can either
984 use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
985 could move to a <tt>Twine</tt> based design.</li>
986
987 <li><tt>isName()</tt> should be replaced with comparison
988 against <tt>getName()</tt> (this is now efficient).
989 </ul>
990</li>
991
992<li>The registration interfaces for backend Targets has changed (what was
993previously <tt>TargetMachineRegistry</tt>). For backend authors, see the <a
994href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
995guide. For clients, the notable API changes are:
996 <ul>
997 <li><tt>TargetMachineRegistry</tt> has been renamed
998 to <tt>TargetRegistry</tt>.</li>
999
1000 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
1001 function to find targets.</li>
1002 </ul>
1003</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]1004</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1005
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1006</div>
1007
1008
1009
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]1010<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1011<div class="doc_section">
1012 <a name="portability">Portability and Supported Platforms</a>
1013</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]1014<!-- *********************************************************************** -->
1015
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1016<div class="doc_text">
1017
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]1018<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]1019
1020<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1021<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1022 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
1023 systems).</li>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1024<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1025 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]1026<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1027<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
1028 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]1029<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]1030<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]1031</ul>
1032
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]1033<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]1034to the machine and operating system on which it is built. However, minor
1035porting may be required to get LLVM to work on new platforms. We welcome your
1036portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1037
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1038</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1039
1040<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1041<div class="doc_section">
1042 <a name="knownproblems">Known Problems</a>
1043</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1044<!-- *********************************************************************** -->
1045
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1046<div class="doc_text">
1047
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1048<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1049listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1050href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1051there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1052
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1053<ul>
1054<li>The llvm-gcc bootstrap will fail with some versions of binutils (e.g. 2.15)
1055 with a message of "<tt><a href="http://llvm.org/PR5004">Error: can not do 8
1056 byte pc-relative relocation</a></tt>" when building C++ code. We intend to
1057 fix this on mainline, but a workaround for 2.6 is to upgrade to binutils
1058 2.17 or later.</li>
1059
1060<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
1061using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]1062See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1063However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
1064for x86/x86-64 has been made available from the third party AuroraUX Project
1065that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
1066</ul>
1067
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1068</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1069
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1070<!-- ======================================================================= -->
1071<div class="doc_subsection">
1072 <a name="experimental">Experimental features included with this release</a>
1073</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1074
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1075<div class="doc_text">
1076
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]1077<p>The following components of this LLVM release are either untested, known to
1078be broken or unreliable, or are in early development. These components should
1079not be relied on, and bugs should not be filed against them, but they may be
1080useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1081components, please contact us on the <a
1082href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1083
1084<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1085<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430 and SystemZ backends are
1086 experimental.</li>
Bill Wendling99dac472009-03-02 07:54:14 +0000[diff] [blame]1087<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1088 supported value for this option. The ELF writer is experimental.</li>
1089<li>The implementation of Andersen's Alias Analysis has many known bugs.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1090</ul>
1091
1092</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1093
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1094<!-- ======================================================================= -->
1095<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1096 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1097</div>
1098
1099<div class="doc_text">
1100
1101<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1102 <li>The X86 backend does not yet support
1103 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1104 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1105 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1106 <li>The X86 backend generates inefficient floating point code when configured
1107 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]1108 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1109 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
1110 runtime currently due
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1111 to <a href="http://llvm.org/PR2255">several</a>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1112 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
1113 the
1114 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1115 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]1116 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1117 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1118</ul>
1119
1120</div>
1121
1122<!-- ======================================================================= -->
1123<div class="doc_subsection">
1124 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1125</div>
1126
1127<div class="doc_text">
1128
1129<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]1130<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1131compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1132</ul>
1133
1134</div>
1135
1136<!-- ======================================================================= -->
1137<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1138 <a name="arm-be">Known problems with the ARM back-end</a>
1139</div>
1140
1141<div class="doc_text">
1142
1143<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1144<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
1145and not well tested. Some features may not work at all, and the code quality
1146may be poor in some cases.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1147<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]1148processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1149results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1150<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1151</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1152</ul>
1153
1154</div>
1155
1156<!-- ======================================================================= -->
1157<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1158 <a name="sparc-be">Known problems with the SPARC back-end</a>
1159</div>
1160
1161<div class="doc_text">
1162
1163<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1164<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1165 support the 64-bit SPARC ABI (-m64).</li>
1166</ul>
1167
1168</div>
1169
1170<!-- ======================================================================= -->
1171<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1172 <a name="mips-be">Known problems with the MIPS back-end</a>
1173</div>
1174
1175<div class="doc_text">
1176
1177<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1178<li>64-bit MIPS targets are not supported yet.</li>
1179</ul>
1180
1181</div>
1182
1183<!-- ======================================================================= -->
1184<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1185 <a name="alpha-be">Known problems with the Alpha back-end</a>
1186</div>
1187
1188<div class="doc_text">
1189
1190<ul>
1191
1192<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1193appropriate nops inserted to ensure restartability.</li>
1194
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1195</ul>
1196</div>
1197
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1198<!-- ======================================================================= -->
1199<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1200 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1201</div>
1202
1203<div class="doc_text">
1204
1205<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1206<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1207 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1208<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1209 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1210 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1211<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1212<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1213</ul>
1214
1215</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1216
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1217
1218<!-- ======================================================================= -->
1219<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1220 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1221</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1222
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1223<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1224
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1225<p>The only major language feature of GCC not supported by llvm-gcc is
1226 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1227 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1228 supported on some targets (these are used when you take the address of a
1229 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1230
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1231<p>If you run into GCC extensions which are not supported, please let us know.
1232</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1233
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1234</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1235
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1236<!-- ======================================================================= -->
1237<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1238 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1239</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1240
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1241<div class="doc_text">
1242
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1243<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]1244tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1245itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1246
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1247<ul>
Anton Korobeynikov0021fc12008-10-11 18:27:16 +0000[diff] [blame]1248<li>Exception handling works well on the X86 and PowerPC targets. Currently
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1249 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1250</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]1251
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1252</div>
1253
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1254<!-- ======================================================================= -->
1255<div class="doc_subsection">
1256 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1257</div>
1258
1259<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1260<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1261<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1262 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1263 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1264</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1265</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1266
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1267<!-- ======================================================================= -->
1268<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1269 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1270</div>
1271
1272<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1273The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1274technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1275<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1276<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1277to lack of trampoline support (pointers to nested functions) on other platforms.
1278However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1279which does support trampolines.</li>
1280<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1281This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1282exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1283Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1284<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1285and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1286(c380004 also fails with gcc-4.2 mainline).
1287If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1288causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1289<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1290<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1291<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1292crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1293<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1294or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1295or use representation clauses that result in a field of a non-discrete type
1296starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1297<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1298'main' as generated by the Ada binder to be invalid</a>.
1299Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1300<tt>envp</tt> rather than integers.</li>
1301<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1302ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1303</ul>
1304</div>
1305
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1306<!-- ======================================================================= -->
1307<div class="doc_subsection">
1308 <a name="ocaml-bindings">Known problems with the O'Caml bindings</a>
1309</div>
1310
1311<div class="doc_text">
1312
1313<p>The <tt>Llvm.Linkage</tt> module is broken, and has incorrect values. Only
1314<tt>Llvm.Linkage.External</tt>, <tt>Llvm.Linkage.Available_externally</tt>, and
1315<tt>Llvm.Linkage.Link_once</tt> will be correct. If you need any of the other linkage
1316modes, you'll have to write an external C library in order to expose the
1317functionality. This has been fixed in the trunk.</p>
1318</div>
1319
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1320<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1321<div class="doc_section">
1322 <a name="additionalinfo">Additional Information</a>
1323</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1324<!-- *********************************************************************** -->
1325
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1326<div class="doc_text">
1327
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1328<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1329href="http://llvm.org">LLVM web page</a>, in particular in the <a
1330href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1331contains versions of the API documentation which is up-to-date with the
1332Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1333You can access versions of these documents specific to this release by going
1334into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1335
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1336<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1337us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1338lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1339
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1340</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1341
1342<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1343
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1344<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1345<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1346 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1347 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1348 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1349 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1350
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1351 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1352 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1353</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1354
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1355</body>
1356</html>