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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / ce4edd647bddec0be61df39962f1a697068891f2 / . / 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.
61-->
62
63
64<!-- Unfinished features in 2.6:
65 gcc plugin.
66 strong phi elim
67 variable debug info for optimized code
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]68 postalloc scheduler: anti dependence breaking, hazard recognizer?
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]69 metadata
70 loop dependence analysis
71 ELF Writer? How stable?
72 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
73 2.7 supports the GDB 7.0 jit interfaces for debug info.
74 2.7 eliminates ADT/iterator.h
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]75 -->
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]76
Chris Lattner547a3912008-10-12 19:47:48 +0000[diff] [blame]77 <!-- for announcement email:
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]78 Logo web page.
79 llvm devmtg
80 compiler_rt
81 KLEE web page at klee.llvm.org
82 Many new papers added to /pubs/
83 Mention gcc plugin.
84
Chris Lattner74c80df2009-02-25 06:34:50 +0000[diff] [blame]85 -->
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]86
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]87<!-- *********************************************************************** -->
88<div class="doc_section">
89 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]90</div>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]91<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]92
93<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]94<p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]95The LLVM 2.6 distribution currently consists of code from the core LLVM
96repository (which roughly includes the LLVM optimizers, code generators
97and supporting tools), the Clang repository and the llvm-gcc repository. In
98addition to this code, the LLVM Project includes other sub-projects that are in
99development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +0000[diff] [blame]100</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]101
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]102</div>
103
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]104
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]105<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]106<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]107<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]108</div>
109
110<div class="doc_text">
111
112<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]113a set of new 'LLVM native' front-end technologies for the C family of languages.
114LLVM 2.6 is the first release to officially include Clang, and it provides a
115production quality C and Objective-C compiler. If you are interested in <a
116href="http://clang.llvm.org/performance.html">fast compiles</a> and
117<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
118encourage you to try it out. Clang currently compiles typical Objective-C code
1193x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
120(which is when the most pressure is on the frontend).</p>
121
122<p>In addition to supporting these languages, C++ support is also <a
123href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
124Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
125If you are interested in Clang C++ support or any other Clang feature, we
126strongly encourage you to get involved on the <a
Chris Lattnerf40c40b2009-02-25 05:09:54 +0000[diff] [blame]127href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
128list</a>.</p>
129
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]130<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]131
Daniel Dunbar13739432008-10-14 23:25:09 +0000[diff] [blame]132<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]133<li>C and Objective-C support are now considered production quality.</li>
134<li>AuroraUX, FreeBSD and OpenBSD are now supported.</li>
135<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
136<li>Many many bugs are fixed and lots of features have been added.</li>
Bill Wendling6bc15282009-03-02 04:28:18 +0000[diff] [blame]137</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]138</div>
139
140<!--=========================================================================-->
141<div class="doc_subsection">
142<a name="clangsa">Clang Static Analyzer</a>
143</div>
144
145<div class="doc_text">
146
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]147<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]148includes an early stage static source code analysis tool for <a
149href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]150in C and Objective-C programs. The tool performs checks to find
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]151bugs that occur on a specific path within a program.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]152
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]153<p>In the LLVM 2.6 time-frame, the analyzer core has undergone several important
154improvements and cleanups and now includes a new <em>Checker</em> interface that
155is intended to eventually serve as a basis for domain-specific checks. Further,
156in addition to generating HTML files for reporting analysis results, the
157analyzer can now also emit bug reports in a structured XML format that is
158intended to be easily readable by other programs.</p>
Ted Kremenek3c3ec0c2008-10-14 05:14:21 +0000[diff] [blame]159
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]160<p>The set of checks performed by the static analyzer continues to expand, and
Ted Kremenek8b3894c2009-02-27 07:01:32 +0000[diff] [blame]161future plans for the tool include full source-level inter-procedural analysis
162and deeper checks such as buffer overrun detection. There are many opportunities
163to extend and enhance the static analyzer, and anyone interested in working on
164this project is encouraged to get involved!</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]165
166</div>
167
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]168<!--=========================================================================-->
169<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]170<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]171</div>
172
173<div class="doc_text">
174<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]175The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]176a JVM and a CLI Virtual Machine (Microsoft .NET is an
177implementation of the CLI) using LLVM for static and just-in-time
178compilation.</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]179
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]180<p>
181VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
182<a href="http://vmkit.llvm.org/releases/">web page</a>. The release includes
Nicolas Geoffray56d313d2008-10-15 20:25:04 +0000[diff] [blame]183bug fixes, cleanup and new features. The major changes are:</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]184
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]185<ul>
186
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]187<li>A new llcj tool to generate shared libraries or executables of Java
188 files.</li>
189<li>Cooperative garbage collection. </li>
190<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
191<li>Implementation of a two-word header for Java objects instead of the original
192 three-word header. </li>
193<li>Better Java specification-compliance: division by zero checks, stack
194 overflow checks, finalization and references support. </li>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000[diff] [blame]195
196</ul>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]197</div>
198
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]199
200<!--=========================================================================-->
201<div class="doc_subsection">
202<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
203</div>
204
205<div class="doc_text">
206<p>
207The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
208is a simple library that provides an implementation of the low-level
209target-specific hooks required by code generation and other runtime components.
210For example, when compiling for a 32-bit target, converting a double to a 64-bit
211unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
212function. The compiler-rt library provides highly optimized implementations of
213this and other low-level routines (some are 3x faster than the equivalent
214libgcc routines).</p>
215
216<p>
217All of the code in the compiler-rt project is available under the standard LLVM
218License, a "BSD-style" license.</p>
219
220</div>
221
222<!--=========================================================================-->
223<div class="doc_subsection">
224<a name="klee">KLEE: Symbolic Execution and Automatic Test Case Generator</a>
225</div>
226
227<div class="doc_text">
228<p>
229The new LLVM <a href="http://klee.llvm.org/">KLEE project</a> is a symbolic
230execution framework for programs in LLVM bitcode form. KLEE tries to
231symbolically evaluate "all" paths through the application and records state
232transitions that lead to fault states. This allows it to construct testcases
233that lead to faults and can even be used to verify algorithms. For more
234details, please see the <a
235href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
236KLEE.</p>
237
238</div>
239
240<!--=========================================================================-->
241<div class="doc_subsection">
242<a name="dragonegg">DragonEgg: GCC-4.5 as an LLVM frontend</a>
243</div>
244
245<div class="doc_text">
246<p>
247The goal of <a href="http://dragonegg.llvm.org/">DragonEgg</a> is to make
248gcc-4.5 act like llvm-gcc without requiring any gcc modifications whatsoever.
Duncan Sands78a1dcc2009-10-15 08:17:44 +0000[diff] [blame]249<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a shared library (dragonegg.so)
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]250that is loaded by gcc at runtime. It uses the new gcc plugin architecture to
251disable the GCC optimizers and code generators, and schedule the LLVM optimizers
252and code generators (or direct output of LLVM IR) instead. Currently only Linux
253and Darwin are supported, and only on x86-32 and x86-64. It should be easy to
254add additional unix-like architectures and other processor families. In theory
255it should be possible to use <a href="http://dragonegg.llvm.org/">DragonEgg</a>
256with any language supported by gcc, however only C and Fortran work well for the
257moment. Ada and C++ work to some extent, while Java, Obj-C and Obj-C++ are so
258far entirely untested. Since gcc-4.5 has not yet been released, neither has
259<a href="http://dragonegg.llvm.org/">DragonEgg</a>. To build
260<a href="http://dragonegg.llvm.org/">DragonEgg</a> you will need to check out the
261development versions of <a href="http://gcc.gnu.org/svn.html/"> gcc</a>,
262<a href="http://llvm.org/docs/GettingStarted.html#checkout">llvm</a> and
263<a href="http://dragonegg.llvm.org/">DragonEgg</a> from their respective
264subversion repositories, and follow the instructions in the
265<a href="http://dragonegg.llvm.org/">DragonEgg</a> README.
266</p>
267
268</div>
269
270
271<!--=========================================================================-->
272<div class="doc_subsection">
273<a name="mc">llvm-mc: Machine Code Toolkit</a>
274</div>
275
276<div class="doc_text">
277<p>
278The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
279better tools for dealing with machine code, object file formats, etc. The idea
280is to be able to generate most of the target specific details of assemblers and
281disassemblers from existing LLVM target .td files (with suitable enhancements),
282and to build infrastructure for reading and writing common object file formats.
283One of the first deliverables is to build a full assembler and integrate it into
284the compiler, which is predicted to substantially reduce compile time in some
285scenarios.
286</p>
287
288<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
289can reliably parse and pretty print (with some encoding information) a
290darwin/x86 .s file successfully, and has the very early phases of a Mach-O
291assembler in progress. Beyond the MC framework itself, major refactoring of the
292LLVM code generator has started. The idea is to make the code generator reason
293about the code it is producing in a much more semantic way, rather than a
294textual way. For example, the code generator now uses MCSection objects to
295represent section assignments, instead of text strings that print to .section
296directives.</p>
297
298<p>MC is an early and ongoing project that will hopefully continue to lead to
299many improvements in the code generator and build infrastructure useful for many
300other situations.
301</p>
302
303</div>
304
305
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]306<!-- *********************************************************************** -->
307<div class="doc_section">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]308 <a name="externalproj">External Open Source Projects Using LLVM 2.6</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]309</div>
310<!-- *********************************************************************** -->
311
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]312<div class="doc_text">
313
314<p>An exciting aspect of LLVM is that it is used as an enabling technology for
315 a lot of other language and tools projects. This section lists some of the
316 projects that have already been updated to work with LLVM 2.6.</p>
317</div>
318
319
320<!--=========================================================================-->
321<div class="doc_subsection">
322<a name="Rubinius">Rubinius</a>
323</div>
324
325<div class="doc_text">
326<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
327for running Ruby code which strives to write as much of the core class
328implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
329uses LLVM to optimize and compile ruby code down to machine code. Techniques
330such as type feedback, method inlining, and uncommon traps are all used to
331remove dynamism from ruby execution and increase performance.</p>
332
333<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
334a counter based JIT, type feedback and speculative method inlining.
335</p>
336
337</div>
338
339<!--=========================================================================-->
340<div class="doc_subsection">
341<a name="macruby">MacRuby</a>
342</div>
343
344<div class="doc_text">
345
346<p>
347<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
348core Mac OS X technologies, such as the Objective-C common runtime and garbage
349collector and the CoreFoundation framework. It is principally developed by
350Apple and aims at enabling the creation of full-fledged Mac OS X applications.
351</p>
352
353<p>
354MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
355expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
356handling.</p>
357
358</div>
359
360
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]361<!--=========================================================================-->
362<div class="doc_subsection">
363<a name="pure">Pure</a>
364</div>
365
366<div class="doc_text">
367<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]368<a href="http://pure-lang.googlecode.com/">Pure</a>
369is an algebraic/functional programming language based on term rewriting.
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]370Programs are collections of equations which are used to evaluate expressions in
371a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]372lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]373built-in list and matrix support (including list and matrix comprehensions) and
374an easy-to-use C interface. The interpreter uses LLVM as a backend to
375 JIT-compile Pure programs to fast native code.</p>
376
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]377<p>Pure versions 0.31 and later have been tested and are known to work with
378LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]379</p>
380</div>
381
382
383<!--=========================================================================-->
384<div class="doc_subsection">
385<a name="ldc">LLVM D Compiler</a>
386</div>
387
388<div class="doc_text">
389<p>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]390<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
391the D Programming Language using the LLVM optimizer and code generator.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]392The LDC project works great with the LLVM 2.6 release. General improvements in
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]393this
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]394cycle have included new inline asm constraint handling, better debug info
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]395support, general bug fixes and better x86-64 support. This has allowed
396some major improvements in LDC, getting it much closer to being as
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]397fully featured as the original DMD compiler from DigitalMars.
398</p>
399</div>
400
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]401<!--=========================================================================-->
402<div class="doc_subsection">
403<a name="RoadsendPHP">Roadsend PHP</a>
404</div>
405
406<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]407<p>
408<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]409source implementation of the PHP programming
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]410language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnercade8222009-03-02 19:07:24 +0000[diff] [blame]411reimplementation of an earlier project that is now based on LLVM.</p>
Chris Lattnerbc31caf2009-02-28 18:58:01 +0000[diff] [blame]412</div>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]413
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]414<!--=========================================================================-->
415<div class="doc_subsection">
416<a name="UnladenSwallow">Unladen Swallow</a>
417</div>
418
419<div class="doc_text">
420<p>
421<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
422branch of <a href="http://python.org/">Python</a> intended to be fully
423compatible and significantly faster. It uses LLVM's optimization passes and JIT
424compiler.</p>
425</div>
426
427<!--=========================================================================-->
428<div class="doc_subsection">
429<a name="llvm-lua">llvm-lua</a>
430</div>
431
432<div class="doc_text">
433<p>
434<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
435and static compiling support to the Lua VM. Lua bytecode is analyzed to
436remove type checks, then LLVM is used to compile the bytecode down to machine
437code.</p>
438</div>
439
440<!--=========================================================================-->
441<div class="doc_subsection">
442<a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
443</div>
444
445<div class="doc_text">
446<p>
447<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
448harness to build OpenJDK using only free software build tools and to provide
449replacements for the not-yet free parts of OpenJDK. One of the extensions that
450IcedTea provides is a new JIT compiler named <a
451href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
452to provide native code generation without introducing processor-dependent
453code.
454</p>
455</div>
456
457
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]458
459<!-- *********************************************************************** -->
460<div class="doc_section">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]461 <a name="whatsnew">What's New in LLVM 2.6?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]462</div>
463<!-- *********************************************************************** -->
464
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]465<div class="doc_text">
466
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]467<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]468minor improvements. Some of the major improvements and new features are listed
469in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]470</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]471
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]472</div>
473
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]474<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]475<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]476<a name="majorfeatures">Major New Features</a>
477</div>
478
479<div class="doc_text">
480
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]481<p>LLVM 2.6 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]482
483<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]484<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>
485 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
486<li>Debug information now includes line numbers when optimizations are enabled.
487 This allows statistical sampling tools like OProfile and Shark to map
488 samples back to source lines.</li>
489<li>LLVM now includes new experimental backends to support the MSP430, SystemZ
490 and BlackFin architectures.</li>
491<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
492 enables support for <a href="LinkTimeOptimization.html">transparent
493 link-time optimization</a> on ELF targets when used with the Gold binutils
494 linker.</li>
495<li>LLVM now supports doing optimization and code generation on multiple
496 threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
497 Programmer's Manual</a> for more information.</li>
498<li>LLVM now has experimental support for <a
499 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
500 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
501 final and the .bc file format may change in future releases. Debug info
502 does not yet use this format in LLVM 2.6.</li>
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]503</ul>
504
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]505</div>
506
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]507<!--=========================================================================-->
508<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]509<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]510</div>
511
512<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]513<p>LLVM IR has several new features for better support of new targets and that
514expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]515
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]516<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]517<li>The <a href="LangRef.html#i_add">add</a>, <a
518 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
519 instructions have been split into integer and floating point versions (like
520 divide and remainder), introducing new <a
521 href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
522 and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
523<li>The <a href="LangRef.html#i_add">add</a>, <a
524 href="LangRef.html#i_sub">sub</a> and <a href="LangRef.html#i_mul">mul</a>
525 instructions now support optional "nsw" and "nuw" bits which indicate that
526 the operation is guaranteed to not overflow (in the signed or
527 unsigned case, respectively). This gives the optimizer more information and
528 can be used for things like C signed integer values, which are undefined on
529 overflow.</li>
530<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
531 optional "exact" flag which indicates that the result of the division is
532 guaranteed to have a remainder of zero. This is useful for optimizing pointer
533 subtraction in C.</li>
534<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
535 supports arbitrary integer index values for array/pointer indices. This
536 allows for better code generation on 16-bit pointer targets like PIC16.</li>
537<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
538 supports an "inbounds" optimization hint that tells the optimizer that the
539 pointer is guaranteed to be within its allocated object.</li>
540<li>LLVM now support a series of new linkage types for global values which allow
541 for better optimization and new capabilities:
542 <ul>
543 <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
544 <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
545 semantics as the non-"odr" linkage types. The difference is that these
546 linkage types indicate that all definitions of the specified function
547 are guaranteed to have the same semantics. This allows inlining
548 templates functions in C++ but not inlining weak functions in C,
549 which previously both got the same linkage type.</li>
550 <li><a href="LangRef.html#linkage_available_externally">available_externally
551 </a> is a new linkage type that gives the optimizer visibility into the
552 definition of a function (allowing inlining and side effect analysis)
553 but that does not cause code to be generated. This allows better
554 optimization of "GNU inline" functions, extern templates, etc.</li>
555 <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
556 new linkage type (which is only useful on Mac OS X) that is used for
557 some metadata generation and other obscure things.</li>
558 </ul></li>
559<li>Finally, target-specific intrinsics can now return multiple values, which
560 is useful for modeling target operations with multiple results.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]561</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]562
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]563</div>
564
565<!--=========================================================================-->
566<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]567<a name="optimizer">Optimizer Improvements</a>
568</div>
569
570<div class="doc_text">
571
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]572<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]573release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]574
575<ul>
576
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]577<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
578 pass has many improvements that allow it to better promote vector unions,
579 variables which are memset, and much more strange code that can happen to
580 do bitfield accesses to register operations. An interesting change is that
581 it now produces "unusual" integer sizes (like i1704) in some cases and lets
582 other optimizers clean things up.</li>
583<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
584 promotes small integer induction variables to 64-bit on 64-bit targets,
585 which provides a major performance boost for much numerical code. It also
586 promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
587 expressions (e.g. getelementptrs), as well as integers.</li>
588<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
589 redundancies of loads in simple cases.</li>
590<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
591 inlining similar arrays from multiple callees into one caller.</li>
592<li>LLVM includes a new experimental Static Single Information (SSI)
593 construction pass.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]594
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]595</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]596
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]597</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]598
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]599
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]600<!--=========================================================================-->
601<div class="doc_subsection">
602<a name="executionengine">Interpreter and JIT Improvements</a>
603</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000[diff] [blame]604
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]605<div class="doc_text">
606
607<ul>
608<li>LLVM has a new "EngineBuilder" class which makes it more obvious how to
609 set up and configure an ExecutionEngine (a JIT or interpreter).</li>
610<li>The JIT now supports generating more than 16M of code.</li>
611<li>When configured with <tt>--with-oprofile</tt>, the JIT can now inform
612 OProfile about JIT'd code, allowing OProfile to get line number and function
613 name information for JIT'd functions.</li>
614<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
615 calling almost arbitrary external (natively compiled) functions.</li>
616<li>Clients of the JIT can now register a 'JITEventListener' object to receive
617 callbacks when the JIT emits or frees machine code. The OProfile support
618 uses this mechanism.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]619</ul>
620
621</div>
622
623<!--=========================================================================-->
624<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]625<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]626</div>
627
628<div class="doc_text">
629
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]630<p>We have put a significant amount of work into the code generator
631infrastructure, which allows us to implement more aggressive algorithms and make
632it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]633
634<ul>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]635
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]636<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc as <tt>-dA</tt>
637 and clang as <tt>-fverbose-asm</tt> or <tt>-dA</tt>) now adds a lot of
638 useful information in comments to
639 the generated .s file. This information includes location information (if
640 built with <tt>-g</tt>) and loop nest information.</li>
641<li>The code generator now supports a new MachineVerifier pass which is useful
642 for finding bugs in targets and codegen passes.</li>
643<li>The Machine LICM is now enabled by default. It hoists instructions out of
644 loops (such as constant pool loads, loads from read-only stubs, vector
645 constant synthesization code, etc.) and is currently configured to only do
646 so when the hoisted operation can be rematerialized.</li>
647<li>The Machine Sinking pass is now enabled by default. This pass moves
648 side-effect free operations down the CFG so that they are executed on fewer
649 paths through a function.</li>
650<li>The code generator now performs "stack slot coloring" of register spills,
651 which allows spill slots to be reused. This leads to smaller stack frames
652 in cases where there are lots of register spills.</li>
653<li>The register allocator has many improvements to take better advantage of
654 commutable operations, various spiller peephole optimizations, and can now
655 coalesce cross-register-class copies.</li>
656<li>Tblgen now supports multiclass inheritance and a number of new string and
657 list operations like <tt>!(subst)</tt>, <tt>!(foreach)</tt>, <tt>!car</tt>,
658 <tt>!cdr</tt>, <tt>!null</tt>, <tt>!if</tt>, <tt>!cast</tt>.
659 These make the .td files more expressive and allow more aggressive factoring
660 of duplication across instruction patterns.</li>
661<li>Target-specific intrinsics can now be added without having to hack VMCore to
662 add them. This makes it easier to maintain out-of-tree targets.</li>
663<li>The instruction selector is better at propagating information about values
664 (such as whether they are sign/zero extended etc.) across basic block
665 boundaries.</li>
666<li>The SelectionDAG datastructure has new nodes for representing buildvector
667 and <a href="http://llvm.org/PR2957">vector shuffle</a> operations. This
668 makes operations and pattern matching more efficient and easier to get
669 right.</li>
670<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
671 the "shrink wrapping" optimization, which moves spills and reloads around in
672 the CFG to avoid doing saves on paths that don't need them.</li>
673<li>LLVM includes new experimental support for writing ELF .o files directly
674 from the compiler. It works well for many simple C testcases, but doesn't
675 support exception handling, debug info, inline assembly, etc.</li>
676<li>Targets can now specify register allocation hints through
677 <tt>MachineRegisterInfo::setRegAllocationHint</tt>. A regalloc hint consists
678 of hint type and physical register number. A hint type of zero specifies a
679 register allocation preference. Other hint type values are target specific
680 which are resolved by <tt>TargetRegisterInfo::ResolveRegAllocHint</tt>. An
681 example is the ARM target which uses register hints to request that the
682 register allocator provide an even / odd register pair to two virtual
683 registers.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]684</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]685</div>
686
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]687<!--=========================================================================-->
688<div class="doc_subsection">
689<a name="x86">X86-32 and X86-64 Target Improvements</a>
690</div>
691
692<div class="doc_text">
693<p>New features of the X86 target include:
694</p>
695
696<ul>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]697
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]698<li>SSE 4.2 builtins are now supported.</li>
699<li>GCC-compatible soft float modes are now supported, which are typically used
700 by OS kernels.</li>
701<li>X86-64 now models implicit zero extensions better, which allows the code
702 generator to remove a lot of redundant zexts. It also models the 8-bit "H"
703 registers as subregs, which allows them to be used in some tricky
704 situations.</li>
705<li>X86-64 now supports the "local exec" and "initial exec" thread local storage
706 model.</li>
707<li>The vector forms of the <a href="LangRef.html#i_icmp">icmp</a> and <a
708 href="LangRef.html#i_fcmp">fcmp</a> instructions now select to efficient
709 SSE operations.</li>
710<li>Support for the win64 calling conventions have improved. The primary
711 missing feature is support for varargs function definitions. It seems to
712 work well for many win64 JIT purposes.</li>
713<li>The X86 backend has preliminary support for <a
714 href="CodeGenerator.html#x86_memory">mapping address spaces to segment
715 register references</a>. This allows you to write GS or FS relative memory
716 accesses directly in LLVM IR for cases where you know exactly what you're
717 doing (such as in an OS kernel). There are some known problems with this
718 support, but it works in simple cases.</li>
719<li>The X86 code generator has been refactored to move all global variable
720 reference logic to one place
721 (<tt>X86Subtarget::ClassifyGlobalReference</tt>) which
722 makes it easier to reason about.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]723
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]724</ul>
725
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]726</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]727
728<!--=========================================================================-->
729<div class="doc_subsection">
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]730<a name="pic16">PIC16 Target Improvements</a>
731</div>
732
733<div class="doc_text">
734<p>New features of the PIC16 target include:
735</p>
736
737<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]738<li>Support for floating-point, indirect function calls, and
739 passing/returning aggregate types to functions.
740<li>The code generator is able to generate debug info into output COFF files.
741<li>Support for placing an object into a specific section or at a specific
742 address in memory.</li>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]743</ul>
744
745<p>Things not yet supported:</p>
746
747<ul>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]748<li>Variable arguments.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]749<li>Interrupts/programs.</li>
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]750</ul>
751
752</div>
753
Chris Lattner11398992009-02-26 07:32:11 +0000[diff] [blame]754<!--=========================================================================-->
755<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]756<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]757</div>
758
759<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]760<p>New features of the ARM target include:
761</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]762
763<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]764
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]765<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
766that implement version v7-A of the ARM architecture. The ARM backend now
767supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]768
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]769<li>The AAPCS-VFP "hard float" calling conventions are also supported with the
770<tt>-float-abi=hard</tt> flag.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]771
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]772<li>The ARM calling convention code is now tblgen generated instead of resorting
773 to C++ code.</li>
774</ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]775
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]776<p>These features are still somewhat experimental
777and subject to change. The Neon intrinsics, in particular, may change in future
778releases of LLVM. ARMv7 support has progressed a lot on top of tree since 2.6
779branched.</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]780
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]781
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]782</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]783
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]784<!--=========================================================================-->
785<div class="doc_subsection">
786<a name="OtherTarget">Other Target Specific Improvements</a>
787</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]788
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]789<div class="doc_text">
790<p>New features of other targets include:
791</p>
792
793<ul>
794<li>Mips now supports O32 Calling Convention.</li>
795<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
796 support, lots of bugs fixed.</li>
797<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
798 Needs more testing.</li>
799</ul>
800
801</div>
802
803<!--=========================================================================-->
804<div class="doc_subsection">
805<a name="newapis">New Useful APIs</a>
806</div>
807
808<div class="doc_text">
809
810<p>This release includes a number of new APIs that are used internally, which
811 may also be useful for external clients.
812</p>
813
814<ul>
815<li>New <a href="http://llvm.org/doxygen/PrettyStackTrace_8h-source.html">
816 <tt>PrettyStackTrace</tt> class</a> allows crashes of llvm tools (and applications
817 that integrate them) to provide more detailed indication of what the
818 compiler was doing at the time of the crash (e.g. running a pass).
819 At the top level for each LLVM tool, it includes the command line arguments.
820 </li>
821<li>New <a href="http://llvm.org/doxygen/StringRef_8h-source.html">StringRef</a>
822 and <a href="http://llvm.org/doxygen/Twine_8h-source.html">Twine</a> classes
823 make operations on character ranges and
824 string concatenation to be more efficient. <tt>StringRef</tt> is just a <tt>const
825 char*</tt> with a length, <tt>Twine</tt> is a light-weight rope.</li>
826<li>LLVM has new <tt>WeakVH</tt>, <tt>AssertingVH</tt> and <tt>CallbackVH</tt>
827 classes, which make it easier to write LLVM IR transformations. <tt>WeakVH</tt>
828 is automatically drops to null when the referenced <tt>Value</tt> is deleted,
829 and is updated across a <tt>replaceAllUsesWith</tt> operation.
830 <tt>AssertingVH</tt> aborts the program if the
831 referenced value is destroyed while it is being referenced. <tt>CallbackVH</tt>
832 is a customizable class for handling value references. See <a
833 href="http://llvm.org/doxygen/ValueHandle_8h-source.html">ValueHandle.h</a>
834 for more information.</li>
835<li>The new '<a href="http://llvm.org/doxygen/Triple_8h-source.html">Triple
836 </a>' class centralizes a lot of logic that reasons about target
837 triples.</li>
838<li>The new '<a href="http://llvm.org/doxygen/ErrorHandling_8h-source.html">
839 llvm_report_error()</a>' set of APIs allows tools to embed the LLVM
840 optimizer and backend and recover from previously unrecoverable errors.</li>
841<li>LLVM has new abstractions for <a
842 href="http://llvm.org/doxygen/Atomic_8h-source.html">atomic operations</a>
843 and <a href="http://llvm.org/doxygen/RWMutex_8h-source.html">reader/writer
844 locks</a>.</li>
845<li>LLVM has new <a href="http://llvm.org/doxygen/SourceMgr_8h-source.html">
846 <tt>SourceMgr</tt> and <tt>SMLoc</tt> classes</a> which implement caret
847 diagnostics and basic include stack processing for simple parsers. It is
848 used by tablegen, llvm-mc, the .ll parser and FileCheck.</li>
849</ul>
850
851
852</div>
853
854<!--=========================================================================-->
855<div class="doc_subsection">
856<a name="otherimprovements">Other Improvements and New Features</a>
857</div>
858
859<div class="doc_text">
860<p>Other miscellaneous features include:</p>
861
862<ul>
863<li>LLVM now includes a new internal '<a
864 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
865 writing much more accurate regression tests that run faster. Please see the
866 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
867 Guide</a> for more information.</li>
868<li>LLVM profile information support has been significantly improved to produce
869correct use counts, and has support for edge profiling with reduced runtime
870overhead. Combined, the generated profile information is both more correct and
871imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
872CPU2000).</li>
873<li>The C bindings (in the llvm/include/llvm-c directory) include many newly
874 supported APIs.</li>
875<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
876 programming language.</li>
877
878<li>The LLVMC driver has several new features:
879 <ul>
880 <li>Dynamic plugins now work on Windows.</li>
881 <li>New option property: init. Makes possible to provide default values for
882 options defined in plugins (interface to <tt>cl::init</tt>).</li>
883 <li>New example: Skeleton, shows how to create a standalone LLVMC-based
884 driver.</li>
885 <li>New example: mcc16, a driver for the PIC16 toolchain.</li>
886 </ul>
887</li>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]888
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]889</ul>
890
891</div>
892
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]893
894<!--=========================================================================-->
895<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]896<a name="changes">Major Changes and Removed Features</a>
897</div>
898
899<div class="doc_text">
900
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]901<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]902on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]903from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]904
905<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]906<li>The Itanium (IA64) backend has been removed. It was not actively supported
907 and had bitrotted.</li>
908<li>The BigBlock register allocator has been removed, it had also bitrotted.</li>
909<li>The C Backend (<tt>-march=c</tt>) is no longer considered part of the LLVM release
910criteria. We still want it to work, but no one is maintaining it and it lacks
911support for arbitrary precision integers and other important IR features.</li>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]912
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]913<li>All LLVM tools now default to overwriting their output file, behaving more
914 like standard unix tools. Previously, this only happened with the '<tt>-f</tt>'
915 option.</li>
916<li>LLVM build now builds all libraries as .a files instead of some
917 libraries as relinked .o files. This requires some APIs like
918 InitializeAllTargets.h.
919 </li>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]920</ul>
921
922
923<p>In addition, many APIs have changed in this release. Some of the major LLVM
924API changes are:</p>
925
926<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]927<li>All uses of <tt>hash_set</tt> and <tt>hash_map</tt> have been removed from
928 the LLVM tree and the wrapper headers have been removed.</li>
929<li>The llvm/Streams.h and <tt>DOUT</tt> member of Debug.h have been removed. The
930 <tt>llvm::Ostream</tt> class has been completely removed and replaced with
931 uses of <tt>raw_ostream</tt>.</li>
932<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
933 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
934 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
935 for clients that will only ever use a single context, the new
936 <tt>getGlobalContext()</tt> API can be used to access a default global
937 context which can be passed in any and all cases where a context is
938 required.
939<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
940<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
941 overloaded for floating-point types. Floating-point addition, subtraction
942 and multiplication are now represented with new operators <tt>FAdd</tt>,
943 <tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
944 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
945 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
946 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
947 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
948<li>The <tt>DynamicLibrary</tt> class can no longer be constructed, its functionality has
949 moved to static member functions.</li>
950<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
951 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
952 <tt>false</tt>, an error will be reported if a file with the given name
953 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
954 be silently truncated (which is the behavior before this flag was
955 added).</li>
956<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
957 longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt>
958 should be used.</li>
959
960<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
961and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
962or <tt>std::string</tt>, as described in
963the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
964clients should be unaffected by this transition, unless they are used to
965<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
9662.6:
967 <ul>
968 <li><tt>getNameStr()</tt> is still available, and matches the old
969 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
970 although more efficient alternatives are now possible.</li>
971
972 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
973 a <tt>std::ostream</tt>, consider migrating
974 to <tt>llvm::raw_ostream</tt>.</li>
975
976 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
977 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
978 Note that this string (as before), may not be the entire name if the
979 name contains embedded null characters.</li>
980
981 <li>If you were using <tt>operator +</tt> on the result of <tt>getName()</tt> and
982 treating the result as an <tt>std::string</tt>, you can either
983 use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
984 could move to a <tt>Twine</tt> based design.</li>
985
986 <li><tt>isName()</tt> should be replaced with comparison
987 against <tt>getName()</tt> (this is now efficient).
988 </ul>
989</li>
990
991<li>The registration interfaces for backend Targets has changed (what was
992previously <tt>TargetMachineRegistry</tt>). For backend authors, see the <a
993href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
994guide. For clients, the notable API changes are:
995 <ul>
996 <li><tt>TargetMachineRegistry</tt> has been renamed
997 to <tt>TargetRegistry</tt>.</li>
998
999 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
1000 function to find targets.</li>
1001 </ul>
1002</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]1003</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1004
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1005</div>
1006
1007
1008
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]1009<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1010<div class="doc_section">
1011 <a name="portability">Portability and Supported Platforms</a>
1012</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]1013<!-- *********************************************************************** -->
1014
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1015<div class="doc_text">
1016
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]1017<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]1018
1019<ul>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1020<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1021 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
1022 systems).</li>
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1023<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]1024 and 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]1025<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1026<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
1027 support is available for native builds with Visual C++).</li>
Chris Lattner7e23d6e2009-10-16 16:30:58 +0000[diff] [blame]1028<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]1029<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]1030</ul>
1031
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]1032<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]1033to the machine and operating system on which it is built. However, minor
1034porting may be required to get LLVM to work on new platforms. We welcome your
1035portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1036
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1037</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1038
1039<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1040<div class="doc_section">
1041 <a name="knownproblems">Known Problems</a>
1042</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1043<!-- *********************************************************************** -->
1044
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1045<div class="doc_text">
1046
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1047<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1048listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1049href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1050there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1051
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1052<ul>
1053<li>The llvm-gcc bootstrap will fail with some versions of binutils (e.g. 2.15)
1054 with a message of "<tt><a href="http://llvm.org/PR5004">Error: can not do 8
1055 byte pc-relative relocation</a></tt>" when building C++ code. We intend to
1056 fix this on mainline, but a workaround for 2.6 is to upgrade to binutils
1057 2.17 or later.</li>
1058
1059<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
1060using the stock GCC 3.x.x series 'out the box',
Chris Lattner554ee4a2009-11-03 21:50:09 +0000[diff] [blame]1061See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1062However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
1063for x86/x86-64 has been made available from the third party AuroraUX Project
1064that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
1065</ul>
1066
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1067</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1068
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1069<!-- ======================================================================= -->
1070<div class="doc_subsection">
1071 <a name="experimental">Experimental features included with this release</a>
1072</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1073
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1074<div class="doc_text">
1075
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]1076<p>The following components of this LLVM release are either untested, known to
1077be broken or unreliable, or are in early development. These components should
1078not be relied on, and bugs should not be filed against them, but they may be
1079useful 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]1080components, please contact us on the <a
1081href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1082
1083<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1084<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430 and SystemZ backends are
1085 experimental.</li>
Bill Wendling99dac472009-03-02 07:54:14 +0000[diff] [blame]1086<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1087 supported value for this option. The ELF writer is experimental.</li>
1088<li>The implementation of Andersen's Alias Analysis has many known bugs.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1089</ul>
1090
1091</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1092
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1093<!-- ======================================================================= -->
1094<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1095 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1096</div>
1097
1098<div class="doc_text">
1099
1100<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1101 <li>The X86 backend does not yet support
1102 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1103 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1104 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1105 <li>The X86 backend generates inefficient floating point code when configured
1106 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]1107 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1108 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
1109 runtime currently due
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1110 to <a href="http://llvm.org/PR2255">several</a>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1111 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
1112 the
1113 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1114 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]1115 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1116 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1117</ul>
1118
1119</div>
1120
1121<!-- ======================================================================= -->
1122<div class="doc_subsection">
1123 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1124</div>
1125
1126<div class="doc_text">
1127
1128<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]1129<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1130compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1131</ul>
1132
1133</div>
1134
1135<!-- ======================================================================= -->
1136<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1137 <a name="arm-be">Known problems with the ARM back-end</a>
1138</div>
1139
1140<div class="doc_text">
1141
1142<ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1143<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
1144and not well tested. Some features may not work at all, and the code quality
1145may be poor in some cases.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1146<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]1147processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1148results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1149<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1150</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1151</ul>
1152
1153</div>
1154
1155<!-- ======================================================================= -->
1156<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1157 <a name="sparc-be">Known problems with the SPARC back-end</a>
1158</div>
1159
1160<div class="doc_text">
1161
1162<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1163<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]1164 support the 64-bit SPARC ABI (-m64).</li>
1165</ul>
1166
1167</div>
1168
1169<!-- ======================================================================= -->
1170<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1171 <a name="mips-be">Known problems with the MIPS back-end</a>
1172</div>
1173
1174<div class="doc_text">
1175
1176<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1177<li>64-bit MIPS targets are not supported yet.</li>
1178</ul>
1179
1180</div>
1181
1182<!-- ======================================================================= -->
1183<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1184 <a name="alpha-be">Known problems with the Alpha back-end</a>
1185</div>
1186
1187<div class="doc_text">
1188
1189<ul>
1190
1191<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1192appropriate nops inserted to ensure restartability.</li>
1193
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1194</ul>
1195</div>
1196
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1197<!-- ======================================================================= -->
1198<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1199 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1200</div>
1201
1202<div class="doc_text">
1203
1204<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1205<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1206 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1207<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1208 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1209 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1210<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1211<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1212</ul>
1213
1214</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1215
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1216
1217<!-- ======================================================================= -->
1218<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1219 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1220</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1221
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1222<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1223
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1224<p>The only major language feature of GCC not supported by llvm-gcc is
1225 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1226 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1227 supported on some targets (these are used when you take the address of a
1228 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1229
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1230<p>If you run into GCC extensions which are not supported, please let us know.
1231</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1232
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1233</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1234
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1235<!-- ======================================================================= -->
1236<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1237 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1238</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1239
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1240<div class="doc_text">
1241
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1242<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]1243tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1244itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1245
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1246<ul>
Anton Korobeynikov0021fc12008-10-11 18:27:16 +0000[diff] [blame]1247<li>Exception handling works well on the X86 and PowerPC targets. Currently
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1248 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1249</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]1250
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1251</div>
1252
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1253<!-- ======================================================================= -->
1254<div class="doc_subsection">
1255 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1256</div>
1257
1258<div class="doc_text">
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1259<ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1260<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1261 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1262 tools/gfortran component for details.</li>
Gabor Greifba10fe02008-11-04 21:50:59 +0000[diff] [blame]1263</ul>
Chris Lattner1eb4df62008-10-30 03:58:13 +0000[diff] [blame]1264</div>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1265
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1266<!-- ======================================================================= -->
1267<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1268 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1269</div>
1270
1271<div class="doc_text">
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1272The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1273technology, and problems should be expected.
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1274<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]1275<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]1276to lack of trampoline support (pointers to nested functions) on other platforms.
1277However, 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]1278which does support trampolines.</li>
1279<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]1280This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1281exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1282Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000[diff] [blame]1283<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1284and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +0000[diff] [blame]1285(c380004 also fails with gcc-4.2 mainline).
1286If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1287causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +0000[diff] [blame]1288<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1289<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1290<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]1291crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1292<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1293or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1294or use representation clauses that result in a field of a non-discrete type
1295starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]1296<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1297'main' as generated by the Ada binder to be invalid</a>.
1298Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1299<tt>envp</tt> rather than integers.</li>
1300<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1301ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1302</ul>
1303</div>
1304
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]1305<!-- ======================================================================= -->
1306<div class="doc_subsection">
1307 <a name="ocaml-bindings">Known problems with the O'Caml bindings</a>
1308</div>
1309
1310<div class="doc_text">
1311
1312<p>The <tt>Llvm.Linkage</tt> module is broken, and has incorrect values. Only
1313<tt>Llvm.Linkage.External</tt>, <tt>Llvm.Linkage.Available_externally</tt>, and
1314<tt>Llvm.Linkage.Link_once</tt> will be correct. If you need any of the other linkage
1315modes, you'll have to write an external C library in order to expose the
1316functionality. This has been fixed in the trunk.</p>
1317</div>
1318
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1319<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1320<div class="doc_section">
1321 <a name="additionalinfo">Additional Information</a>
1322</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1323<!-- *********************************************************************** -->
1324
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1325<div class="doc_text">
1326
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1327<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1328href="http://llvm.org">LLVM web page</a>, in particular in the <a
1329href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1330contains versions of the API documentation which is up-to-date with the
1331Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1332You can access versions of these documents specific to this release by going
1333into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1334
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1335<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]1336us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1337lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1338
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1339</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1340
1341<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1342
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1343<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1344<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1345 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1346 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1347 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1348 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]1349
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1350 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1351 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1352</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1353
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1354</body>
1355</html>