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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 97b01a82c04abd65f78630f18ad37faf4bdd4303 / . / docs / ReleaseNotes.html
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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4<head>
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Dan Gohmanb44f6c62010-05-03 23:51:05 +0000[diff] [blame]8 <title>LLVM 2.8 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]9</head>
10<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]11
Dan Gohmanb44f6c62010-05-03 23:51:05 +0000[diff] [blame]12<div class="doc_title">LLVM 2.8 Release Notes</div>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]13
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]14<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greifee2187a2010-04-22 10:21:43 +0000[diff] [blame]15 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattner0e464a92010-03-17 04:02:39 +0000[diff] [blame]16
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]17<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]18 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]19 <li><a href="#subproj">Sub-project Status Update</a></li>
Dan Gohmanb44f6c62010-05-03 23:51:05 +0000[diff] [blame]20 <li><a href="#externalproj">External Projects Using LLVM 2.8</a></li>
21 <li><a href="#whatsnew">What's New in LLVM 2.8?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]22 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]23 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]24 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]25</ol>
26
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]27<div class="doc_author">
Dan Gohman44aa9212008-10-14 16:23:02 +0000[diff] [blame]28 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]29</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]30
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]31<!--
Chris Lattner7b91eda2010-04-22 05:41:35 +0000[diff] [blame]32<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]33release.<br>
34You may prefer the
Dan Gohmanb44f6c62010-05-03 23:51:05 +0000[diff] [blame]35<a href="http://llvm.org/releases/2.7/docs/ReleaseNotes.html">LLVM 2.7
36Release Notes</a>.</h1>
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]37-->
Jeffrey Yasskinbec48772010-01-28 01:14:43 +0000[diff] [blame]38
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]39<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]40<div class="doc_section">
41 <a name="intro">Introduction</a>
42</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]43<!-- *********************************************************************** -->
44
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]45<div class="doc_text">
46
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]47<p>This document contains the release notes for the LLVM Compiler
Dan Gohman7ae3ac82010-05-03 23:52:21 +0000[diff] [blame]48Infrastructure, release 2.8. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]49major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]50All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]51href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]52
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]53<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]54release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]55web site</a>. If you have questions or comments, the <a
Chris Lattnerc66bfef2010-03-17 04:41:49 +0000[diff] [blame]56href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
57Mailing List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]58
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]59<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]60main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +0000[diff] [blame]61current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]62<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]63
64</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]65
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]66
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]67<!--
68Almost dead code.
69 include/llvm/Analysis/LiveValues.h => Dan
70 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
Chris Lattner61c70e92010-08-28 04:09:24 +0000[diff] [blame]71 GEPSplitterPass
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]72-->
73
74
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]75<!-- Features that need text if they're finished for 2.9:
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]76 combiner-aa?
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]77 strong phi elim
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]78 loop dependence analysis
Chris Lattner885b6612010-08-28 16:33:36 +0000[diff] [blame]79 TBAA
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]80 CorrelatedValuePropagation
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]81 -->
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]82
83 <!-- Announcement, lldb, libc++ -->
Chris Lattnerafa41632010-09-29 07:25:03 +0000[diff] [blame]84
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]85
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]86<!-- *********************************************************************** -->
87<div class="doc_section">
88 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]89</div>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]90<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]91
92<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]93<p>
Dan Gohmanb44f6c62010-05-03 23:51:05 +0000[diff] [blame]94The LLVM 2.8 distribution currently consists of code from the core LLVM
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]95repository (which roughly includes the LLVM optimizers, code generators
96and supporting tools), the Clang repository and the llvm-gcc repository. In
97addition to this code, the LLVM Project includes other sub-projects that are in
98development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +0000[diff] [blame]99</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]100
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]101</div>
102
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]103
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]104<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]105<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]106<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]107</div>
108
109<div class="doc_text">
110
Chris Lattner095539f2010-04-26 17:42:18 +0000[diff] [blame]111<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
112C++, and Objective-C languages. Clang aims to provide a better user experience
113through expressive diagnostics, a high level of conformance to language
114standards, fast compilation, and low memory use. Like LLVM, Clang provides a
115modular, library-based architecture that makes it suitable for creating or
116integrating with other development tools. Clang is considered a
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]117production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
118(32- and 64-bit), and for darwin-arm targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]119
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]120<p>In the LLVM 2.8 time-frame, the Clang team has made many improvements:</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000[diff] [blame]121
Douglas Gregorf2409d52010-10-04 07:02:35 +0000[diff] [blame]122 <ul>
123 <li>Clang C++ is now feature-complete with respect to the ISO C++ 1998 and 2003 standards.</li>
124 <li>Added support for Objective-C++.</li>
125 <li>Clang now uses LLVM-MC to directly generate object code and to parse inline assembly (on Darwin).</li>
126 <li>Introduced many new warnings, including <code>-Wmissing-field-initializers</code>, <code>-Wshadow</code>, <code>-Wno-protocol</code>, <code>-Wtautological-compare</code>, <code>-Wstrict-selector-match</code>, <code>-Wcast-align</code>, <code>-Wunused</code> improvements, and greatly improved format-string checking.</li>
127 <li>Introduced the "libclang" library, a C interface to Clang intended to support IDE clients.</li>
128 <li>Added support for <code>#pragma GCC visibility</code>, <code>#pragma align</code>, and others.</li>
Duncan Sands051f2ee2010-10-04 09:11:50 +0000[diff] [blame]129 <li>Added support for SSE, ARM NEON, and Altivec.</li>
Daniel Dunbar4a517fc2010-10-04 17:06:49 +0000[diff] [blame]130 <li>Improved support for many Microsoft extensions.</li>
Douglas Gregorf2409d52010-10-04 07:02:35 +0000[diff] [blame]131 <li>Implemented support for blocks in C++.</li>
132 <li>Implemented precompiled headers for C++.</li>
133 <li>Improved abstract syntax trees to retain more accurate source information.</li>
Daniel Dunbar4a517fc2010-10-04 17:06:49 +0000[diff] [blame]134 <li>Added driver support for handling LLVM IR and bitcode files directly.</li>
135 <li>Major improvements to compiler correctness for exception handling.</li>
136 <li>Improved generated code quality in some areas:
137 <ul>
138 <li>Good code generation for X86-32 and X86-64 ABI handling.</li>
139 <li>Improved code generation for bit-fields, although important work remains.</li>
140 </ul>
141 </li>
Douglas Gregorf2409d52010-10-04 07:02:35 +0000[diff] [blame]142 </ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000[diff] [blame]143</div>
144
145<!--=========================================================================-->
146<div class="doc_subsection">
147<a name="clangsa">Clang Static Analyzer</a>
148</div>
149
150<div class="doc_text">
151
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]152<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
153 project is an effort to use static source code analysis techniques to
154 automatically find bugs in C and Objective-C programs (and hopefully <a
155 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
156 future</a>!). The tool is very good at finding bugs that occur on specific
157 paths through code, such as on error conditions.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000[diff] [blame]158
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000[diff] [blame]159<p>The LLVM 2.8 release fixes a number of bugs and slightly improves precision
160 over 2.7, but there are no major new features in the release.
Chris Lattner8cdd7932010-04-22 06:38:11 +0000[diff] [blame]161</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]162
163</div>
164
Chris Lattner96a445e2008-10-13 18:01:01 +0000[diff] [blame]165<!--=========================================================================-->
166<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]167<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]168</div>
169
170<div class="doc_text">
171<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]172<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000[diff] [blame]173gcc-4.5. Unlike llvm-gcc, dragonegg in theory does not require any gcc-4.5
174modifications whatsoever (currently one small patch is needed) thanks to the
175new <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>.
176DragonEgg is a gcc plugin that makes gcc-4.5 use the LLVM optimizers and code
177generators instead of gcc's, just like with llvm-gcc.
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]178</p>
179
180<p>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000[diff] [blame]181DragonEgg is still a work in progress, but it is able to compile a lot of code,
182for example all of gcc, LLVM and clang. Currently Ada, C, C++ and Fortran work
183well, while all other languages either don't work at all or only work poorly.
184For the moment only the x86-32 and x86-64 targets are supported, and only on
185linux and darwin (darwin may need additional gcc patches).
Duncan Sands749fd832010-04-02 09:23:15 +0000[diff] [blame]186</p>
187
188<p>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000[diff] [blame]189The 2.8 release has the following notable changes:
190<ul>
191<li>The plugin loads faster due to exporting fewer symbols.</li>
192<li>Additional vector operations such as addps256 are now supported.</li>
193<li>Ada global variables with no initial value are no longer zero initialized,
194resulting in better optimization.</li>
195<li>The '-fplugin-arg-dragonegg-enable-gcc-optzns' flag now runs all gcc
196optimizers, rather than just a handful.</li>
197<li>Fortran programs using common variables now link correctly.</li>
198<li>GNU OMP constructs no longer crash the compiler.</li>
199</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]200</p>
201
202</div>
203
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]204<!--=========================================================================-->
205<div class="doc_subsection">
206<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
207</div>
208
209<div class="doc_text">
210<p>
211The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
212a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
213just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage
214collectors, and can be configured to use MMTk's copy mark-sweep garbage
215collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained.
216</p>
217</div>
218
219<!--=========================================================================-->
220<div class="doc_subsection">
221<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
222</div>
223
224<div class="doc_text">
225<p>
226The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
227is a simple library that provides an implementation of the low-level
228target-specific hooks required by code generation and other runtime components.
229For example, when compiling for a 32-bit target, converting a double to a 64-bit
230unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
231function. The compiler-rt library provides highly optimized implementations of
232this and other low-level routines (some are 3x faster than the equivalent
233libgcc routines).</p>
234
235<p>
236All of the code in the compiler-rt project is available under the standard LLVM
237License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports
238soft floating point (for targets that don't have a real floating point unit),
239and includes an extensive testsuite for the "blocks" language feature and the
240blocks runtime included in compiler_rt.</p>
241
242</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]243
244<!--=========================================================================-->
245<div class="doc_subsection">
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]246<a name="lldb">LLDB: Low Level Debugger</a>
247</div>
248
249<div class="doc_text">
250<p>
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]251<a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
252umbrella of projects. LLDB is a next generation, high-performance debugger. It
253is built as a set of reusable components which highly leverage existing
254libraries in the larger LLVM Project, such as the Clang expression parser, the
255LLVM disassembler and the LLVM JIT.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]256
257<p>
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]258LLDB is in early development and not included as part of the LLVM 2.8 release,
259but is mature enough to support basic debugging scenarios on Mac OS X in C,
260Objective-C and C++. We'd really like help extending and expanding LLDB to
261support new platforms, new languages, new architectures, and new features.
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]262</p>
263
264</div>
265
266<!--=========================================================================-->
267<div class="doc_subsection">
268<a name="libc++">libc++: C++ Standard Library</a>
269</div>
270
271<div class="doc_text">
272<p>
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]273<a href="http://libc++.llvm.org/">libc++</a> is another new member of the LLVM
274family. It is an implementation of the C++ standard library, written from the
275ground up to specifically target the forthcoming C++'0X standard and focus on
276delivering great performance.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]277
278<p>
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]279As of the LLVM 2.8 release, libc++ is virtually feature complete, but would
280benefit from more testing and better integration with Clang++. It is also
281looking forward to the C++ committee finalizing the C++'0x standard.
Chris Lattnere07043c2010-09-29 05:30:03 +0000[diff] [blame]282</p>
283
284</div>
285
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]286
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000[diff] [blame^]287
288<!--=========================================================================-->
289<div class="doc_subsection">
290<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
291</div>
292
293<div class="doc_text">
294<p>
295<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
296programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
297through the application and records state transitions that lead to fault
298states. This allows it to construct testcases that lead to faults and can even
299be used to verify some algorithms.
300</p>
301
302<p>Although KLEE does not have any major new features as of 2.8, we have made
303various minor improvements, particular to ease development:</p>
304<ul>
305 <li>Added support for LLVM 2.8. KLEE currently maintains compatibility with
306 LLVM 2.6, 2.7, and 2.8.</li>
307 <li>Added a buildbot for 2.6, 2.7, and trunk. A 2.8 buildbot will be coming
308 soon following release.</li>
309 <li>Fixed many C++ code issues to allow building with Clang++. Mostly
310 complete, except for the version of MiniSAT which is inside the KLEE STP
311 version.</li>
312 <li>Improved support for building with separate source and build
313 directories.</li>
314 <li>Added support for "long double" on x86.</li>
315 <li>Initial work on KLEE support for using 'lit' test runner instead of
316 DejaGNU.</li>
317 <li>Added <tt>configure</tt> support for using an external version of
318 STP.</li>
319</ul>
320
321</div>
322
323
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]324<!-- *********************************************************************** -->
325<div class="doc_section">
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]326 <a name="externalproj">External Open Source Projects Using LLVM 2.8</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000[diff] [blame]327</div>
328<!-- *********************************************************************** -->
329
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]330<div class="doc_text">
331
332<p>An exciting aspect of LLVM is that it is used as an enabling technology for
333 a lot of other language and tools projects. This section lists some of the
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]334 projects that have already been updated to work with LLVM 2.8.</p>
Chris Lattner7c8e7962010-04-26 17:38:10 +0000[diff] [blame]335</div>
336
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000[diff] [blame]337<!--=========================================================================-->
338<div class="doc_subsection">
339<a name="tce">TTA-based Codesign Environment (TCE)</a>
340</div>
341
342<div class="doc_text">
343<p>
344<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
345application-specific processors (ASP) based on the Transport triggered
346architecture (TTA). The toolset provides a complete co-design flow from C/C++
347programs down to synthesizable VHDL and parallel program binaries. Processor
348customization points include the register files, function units, supported
349operations, and the interconnection network.</p>
350
351<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
352independent optimizations and also for parts of code generation. It generates
353new LLVM-based code generators "on the fly" for the designed TTA processors and
354loads them in to the compiler backend as runtime libraries to avoid per-target
355recompilation of larger parts of the compiler chain.</p>
356
357</div>
358
359<!--=========================================================================-->
360<div class="doc_subsection">
361<a name="Horizon">Horizon Bytecode Compiler</a>
362</div>
363
364<div class="doc_text">
365<p>
366<a href="http://www.quokforge.org/projects/horizon">Horizon</a> is a bytecode
367language and compiler written on top of LLVM, intended for producing
368single-address-space managed code operating systems that
369run faster than the equivalent multiple-address-space C systems.
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]370More in-depth blurb is available on the <a
371href="http://www.quokforge.org/projects/horizon/wiki/Wiki">wiki</a>.</p>
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000[diff] [blame]372
373</div>
374
375<!--=========================================================================-->
376<div class="doc_subsection">
377<a name="clamav">Clam AntiVirus</a>
378</div>
379
380<div class="doc_text">
381<p>
382<a href=http://www.clamav.net>Clam AntiVirus</a> is an open source (GPL)
383anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail
384gateways. Since version 0.96 it has <a
385href="http://vrt-sourcefire.blogspot.com/2010/09/introduction-to-clamavs-low-level.html">bytecode
386signatures</a> that allow writing detections for complex malware. It
387uses LLVM's JIT to speed up the execution of bytecode on
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]388X86, X86-64, PPC32/64, falling back to its own interpreter otherwise.
389The git version was updated to work with LLVM 2.8.
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000[diff] [blame]390</p>
391
392<p>The <a
393href="http://git.clamav.net/gitweb?p=clamav-bytecode-compiler.git;a=blob_plain;f=docs/user/clambc-user.pdf">
394ClamAV bytecode compiler</a> uses Clang and LLVM to compile a C-like
395language, insert runtime checks, and generate ClamAV bytecode.</p>
396
397</div>
398
399<!--=========================================================================-->
400<div class="doc_subsection">
401<a name="pure">Pure</a>
402</div>
403
404<div class="doc_text">
405<p>
406<a href="http://pure-lang.googlecode.com/">Pure</a>
407is an algebraic/functional
408programming language based on term rewriting. Programs are collections
409of equations which are used to evaluate expressions in a symbolic
410fashion. Pure offers dynamic typing, eager and lazy evaluation, lexical
411closures, a hygienic macro system (also based on term rewriting),
412built-in list and matrix support (including list and matrix
413comprehensions) and an easy-to-use C interface. The interpreter uses
414LLVM as a backend to JIT-compile Pure programs to fast native code.</p>
415
416<p>Pure versions 0.44 and later have been tested and are known to work with
417LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).</p>
418
419</div>
420
421<!--=========================================================================-->
422<div class="doc_subsection">
423<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
424</div>
425
426<div class="doc_text">
427<p>
428<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
429state-of-the-art programming suite for
430Haskell, a standard lazy functional programming language. It includes
431an optimizing static compiler generating good code for a variety of
432platforms, together with an interactive system for convenient, quick
433development.</p>
434
435<p>In addition to the existing C and native code generators, GHC 7.0 now
436supports an <a
437href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
438code generator</a>. GHC supports LLVM 2.7 and later.</p>
439
440</div>
441
442<!--=========================================================================-->
443<div class="doc_subsection">
444<a name="Clay">Clay Programming Language</a>
445</div>
446
447<div class="doc_text">
448<p>
Chris Lattner97fe6452010-09-30 01:12:09 +0000[diff] [blame]449<a href="http://tachyon.in/clay/">Clay</a> is a new systems programming
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000[diff] [blame]450language that is specifically designed for generic programming. It makes
451generic programming very concise thanks to whole program type propagation. It
452uses LLVM as its backend.</p>
453
454</div>
Chris Lattner3a1d4cf2010-04-22 21:34:16 +0000[diff] [blame]455
Chris Lattnere0518442010-10-01 06:34:49 +0000[diff] [blame]456<!--=========================================================================-->
457<div class="doc_subsection">
458<a name="llvm-py">llvm-py Python Bindings for LLVM</a>
459</div>
460
461<div class="doc_text">
462<p>
463<a href="http://www.mdevan.org/llvm-py/">llvm-py</a> has been updated to work
464with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a
465compiler backend or a VM in Python.</p>
466
467</div>
468
469
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000[diff] [blame]470<!--=========================================================================-->
471<div class="doc_subsection">
472<a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a>
473</div>
474
475<div class="doc_text">
476<p>
477<a href="http://faust.grame.fr">FAUST</a> is a compiled language for real-time
478audio signal processing. The name FAUST stands for Functional AUdio STream. Its
479programming model combines two approaches: functional programming and block
480diagram composition. In addition with the C, C++, JAVA output formats, the
481Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and
4822.8.</p>
483
484</div>
485
486<!--=========================================================================-->
487<div class="doc_subsection">
488<a name="jade">Jade Just-in-time Adaptive Decoder Engine</a>
489</div>
490
491<div class="doc_text">
492<p><a
493href="http://sourceforge.net/apps/trac/orcc/wiki/JadeDocumentation">Jade</a>
494(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using
495LLVM for just-in-time compilation of video decoder configurations. Those
496configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee.
497MPEG RVC standard is built on a stream-based dataflow representation of
498decoders. It is composed of a standard library of coding tools written in
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]499RVC-CAL language and a dataflow configuration &#8212; block diagram &#8212;
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000[diff] [blame]500of a decoder.</p>
501
502<p>Jade project is hosted as part of the <a href="http://orcc.sf.net">Open
503RVC-CAL Compiler</a> and requires it to translate the RVC-CAL standard library
504of video coding tools into an LLVM assembly code.</p>
505
506</div>
507
508<!--=========================================================================-->
509<div class="doc_subsection">
510<a name="neko_llvm_jit">LLVM JIT for Neko VM</a>
511</div>
512
513<div class="doc_text">
514<p><a href="http://github.com/vava/neko_llvm_jit">Neko LLVM JIT</a>
515replaces the standard Neko JIT with an LLVM-based implementation. While not
516fully complete, it is already providing a 1.5x speedup on 64-bit systems.
517Neko LLVM JIT requires LLVM 2.8 or later.</p>
518
519</div>
520
521<!--=========================================================================-->
522<div class="doc_subsection">
523<a name="crack">Crack Scripting Language</a>
524</div>
525
526<div class="doc_text">
527<p>
528<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide
529the ease of development of a scripting language with the performance of a
530compiled language. The language derives concepts from C++, Java and Python,
531incorporating object-oriented programming, operator overloading and strong
532typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release
533builds on LLVM 2.8.</p>
534
535</div>
536
537<!--=========================================================================-->
538<div class="doc_subsection">
539<a name="DresdenTM">Dresden TM Compiler (DTMC)</a>
540</div>
541
542<div class="doc_text">
543<p>
544<a href="http://tm.inf.tu-dresden.de">DTMC</a> provides support for
545Transactional Memory, which is an easy-to-use and efficient way to synchronize
546accesses to shared memory. Transactions can contain normal C/C++ code (e.g.,
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]547<code>__transaction { list.remove(x); x.refCount--; }</code>) and will be executed
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000[diff] [blame]548virtually atomically and isolated from other transactions.</p>
549
550</div>
551
552<!--=========================================================================-->
553<div class="doc_subsection">
Chris Lattnerc5fd1562010-10-04 16:06:37 +0000[diff] [blame]554<a name="Kai">Kai Programming Language</a>
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000[diff] [blame]555</div>
556
557<div class="doc_text">
558<p>
559<a href="http://www.oriontransfer.co.nz/research/kai">Kai</a> (Japanese 会 for
560meeting/gathering) is an experimental interpreter that provides a highly
561extensible runtime environment and explicit control over the compilation
562process. Programs are defined using nested symbolic expressions, which are all
563parsed into first-class values with minimal intrinsic semantics. Kai can
564generate optimised code at run-time (using LLVM) in order to exploit the nature
565of the underlying hardware and to integrate with external software libraries.
566It is a unique exploration into world of dynamic code compilation, and the
567interaction between high level and low level semantics.</p>
568
569</div>
570
Chris Lattner75547712010-10-03 23:49:06 +0000[diff] [blame]571<!--=========================================================================-->
572<div class="doc_subsection">
573<a name="OSL">OSL: Open Shading Language</a>
574</div>
575
576<div class="doc_text">
577<p>
578<a href="http://code.google.com/p/openshadinglanguage/">OSL</a> is a shading
579language designed for use in physically based renderers and in particular
580production rendering. By using LLVM instead of the interpreter, it was able to
581meet its performance goals (&gt;= C-code) while retaining the benefits of
582runtime specialization and a portable high-level language.
583</p>
584
585</div>
586
587
Chris Lattnere0518442010-10-01 06:34:49 +0000[diff] [blame]588
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]589<!-- *********************************************************************** -->
590<div class="doc_section">
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]591 <a name="whatsnew">What's New in LLVM 2.8?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]592</div>
593<!-- *********************************************************************** -->
594
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]595<div class="doc_text">
596
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]597<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]598minor improvements. Some of the major improvements and new features are listed
599in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]600</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]601
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]602</div>
603
604<!--=========================================================================-->
605<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]606<a name="majorfeatures">Major New Features</a>
607</div>
608
609<div class="doc_text">
610
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]611<p>LLVM 2.8 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]612
613<ul>
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]614<li>As mentioned above, <a href="#libc++">libc++</a> and <a
615 href="#lldb">LLDB</a> are major new additions to the LLVM collective.</li>
616<li>LLVM 2.8 now has pretty decent support for debugging optimized code. You
617 should be able to reliably get debug info for function arguments, assuming
618 that the value is actually available where you have stopped.</li>
619</ul>
620<li>A new 'llvm-diff' tool is available that does a semantic diff of .ll
621 files.</li>
622<li>The <a href="#mc">MC subproject</a> has made major progress in this release.
623 Direct .o file writing support for darwin/x86[-64] is now reliable and
624 support for other targets and object file formats are in progress.</li>
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]625</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000[diff] [blame]626
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]627</div>
628
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]629<!--=========================================================================-->
630<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]631<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]632</div>
633
634<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]635<p>LLVM IR has several new features for better support of new targets and that
636expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]637
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]638<ul>
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]639<li>The <a href="LangRef.html#int_libc">memcpy, memmove, and memset</a>
640 intrinsics now take address space qualified pointers and a bit to indicate
641 whether the transfer is "<a href="LangRef.html#volatile">volatile</a>" or not.
642</li>
643<li>Per-instruction debug info metadata is much faster and uses less memory by
644 using the new DebugLoc class.</li>
645<li>LLVM IR now has a more formalized concept of "<a
646 href="LangRef.html#trapvalues">trap values</a>", which allow the optimizer
647 to optimize more aggressively in the presence of undefined behavior, while
648 still producing predictable results.</li>
649<li>LLVM IR now supports two new <a href="LangRef.html#linkage">linkage
650 types</a> (linker_private_weak and linker_private_weak_def_auto) which map
651 onto some obscure MachO concepts.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]652</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000[diff] [blame]653
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]654</div>
655
656<!--=========================================================================-->
657<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]658<a name="optimizer">Optimizer Improvements</a>
659</div>
660
661<div class="doc_text">
662
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]663<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]664release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]665
666<ul>
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]667<li>As mentioned above, the optimizer now has support for updating debug
668 information as it goes. A key aspect of this is the new <a
669 href="SourceLevelDebugging.html#format_common_value">llvm.dbg.value</a>
670 intrinsic. This intrinsic represents debug info for variables that are
671 promoted to SSA values (typically by mem2reg or the -scalarrepl passes).</li>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]672
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]673<li>The JumpThreading pass is now much more aggressive about implied value
674 relations, allowing it to thread conditions like "a == 4" when a is known to
675 be 13 in one of the predecessors of a block. It does this in conjunction
676 with the new LazyValueInfo analysis pass.</li>
677<li>The new RegionInfo analysis pass identifies single-entry single-exit regions
678 in the CFG. You can play with it with the "opt -regions analyze" or
679 "opt -view-regions" commands.</li>
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]680<li>The loop optimizer has significantly improved strength reduction and analysis
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]681 capabilities. Notably it is able to build on the trap value and signed
682 integer overflow information to optimize &lt;= and &gt;= loops.</li>
683<li>The CallGraphSCCPassManager now has some basic support for iterating within
684 an SCC when a optimizer devirtualizes a function call. This allows inlining
685 through indirect call sites that are devirtualized by store-load forwarding
686 and other optimizations.</li>
687<li>The new <A href="Passes.html#loweratomic">-loweratomic</a> pass is available
688 to lower atomic instructions into their non-atomic form. This can be useful
689 to optimize generic code that expects to run in a single-threaded
690 environment.</li>
691</ul>
692
693<!--
694<p>In addition to these features that are done in 2.8, there is preliminary
695 support in the release for Type Based Alias Analysis
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]696 Preliminary work on TBAA but not usable in 2.8.
697 New CorrelatedValuePropagation pass, not on by default in 2.8 yet.
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]698-->
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]699
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]700</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]701
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]702<!--=========================================================================-->
703<div class="doc_subsection">
Chris Lattner4ba2b652010-09-30 16:31:33 +0000[diff] [blame]704<a name="mc">MC Level Improvements</a>
705</div>
706
707<div class="doc_text">
708<p>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]709The LLVM Machine Code (aka MC) subsystem was created to solve a number
Chris Lattner4ba2b652010-09-30 16:31:33 +0000[diff] [blame]710of problems in the realm of assembly, disassembly, object file format handling,
711and a number of other related areas that CPU instruction-set level tools work
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]712in.</p>
713
714<p>The MC subproject has made great leaps in LLVM 2.8. For example, support for
715 directly writing .o files from LLC (and clang) now works reliably for
716 darwin/x86[-64] (including inline assembly support) and the integrated
717 assembler is turned on by default in Clang for these targets. This provides
718 improved compile times among other things.</p>
719
720<ul>
721<li>The entire compiler has converted over to using the MCStreamer assembler API
722 instead of writing out a .s file textually.</li>
723<li>The "assembler parser" is far more mature than in 2.7, supporting a full
724 complement of directives, now supports assembler macros, etc.</li>
725<li>The "assembler backend" has been completed, including support for relaxation
726 relocation processing and all the other things that an assembler does.</li>
727<li>The MachO file format support is now fully functional and works.</li>
728<li>The MC disassembler now fully supports ARM and Thumb. ARM assembler support
729 is still in early development though.</li>
730<li>The X86 MC assembler now supports the X86 AES and AVX instruction set.</li>
Chris Lattner3bdcda12010-10-04 03:58:12 +0000[diff] [blame]731<li>Work on ELF and COFF object files and ARM target support is well underway,
732 but isn't useful yet in LLVM 2.8. Please contact the llvmdev mailing list
733 if you're interested in this.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]734</ul>
735
736<p>For more information, please see the <a
Chris Lattner4ba2b652010-09-30 16:31:33 +0000[diff] [blame]737href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
738LLVM MC Project Blog Post</a>.
739</p>
740
Chris Lattner4ba2b652010-09-30 16:31:33 +0000[diff] [blame]741</div>
742
743
Chris Lattner4ba2b652010-09-30 16:31:33 +0000[diff] [blame]744<!--=========================================================================-->
745<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]746<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]747</div>
748
749<div class="doc_text">
750
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]751<p>We have put a significant amount of work into the code generator
752infrastructure, which allows us to implement more aggressive algorithms and make
753it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]754
755<ul>
Chris Lattner3bdcda12010-10-04 03:58:12 +0000[diff] [blame]756<li>The clang/gcc -momit-leaf-frame-pointer argument is now supported.</li>
757<li>The clang/gcc -ffunction-sections and -fdata-sections arguments are now
758 supported on ELF targets (like GCC).</li>
759<li>The MachineCSE pass is now tuned and on by default. It eliminates common
760 subexpressions that are exposed when lowering to machine instructions.</li>
761<li>The "local" register allocator was replaced by a new "fast" register
762 allocator. This new allocator (which is often used at -O0) is substantially
763 faster and produces better code than the old local register allocator.</li>
764<li>A new LLC "-regalloc=default" option is available, which automatically
765 chooses a register allocator based on the -O optimization level.</li>
766<li>The common code generator code was modified to promote illegal argument and
767 return value vectors to wider ones when possible instead of scalarizing
768 them. For example, &lt;3 x float&gt; will now pass in one SSE register
769 instead of 3 on X86. This generates substantially better code since the
770 rest of the code generator was already expecting this.</li>
771<li>The code generator uses a new "COPY" machine instruction. This speeds up
772 the code generator and eliminates the need for targets to implement the
773 isMoveInstr hook. Also, the copyRegToReg hook was renamed to copyPhysReg
774 and simplified.</li>
775<li>The code generator now has a "LocalStackSlotPass", which optimizes stack
776 slot access for targets (like ARM) that have limited stack displacement
777 addressing.</li>
778<li>A new "PeepholeOptimizer" is available, which eliminates sign and zero
779 extends, and optimizes away compare instructions when the condition result
780 is available from a previous instruction.</li>
781<li>Atomic operations now get legalized into simpler atomic operations if not
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]782 natively supported, easing the implementation burden on targets.</li>
Chris Lattnerb822f652010-10-04 16:46:07 +0000[diff] [blame]783<li>We have added two new bottom-up pre-allocation register pressure aware schedulers:
784<ol>
785<li>The hybrid scheduler schedules aggressively to minimize schedule length when registers are available and avoid overscheduling in high pressure situations.</li>
786<li>The instruction-level-parallelism scheduler schedules for maximum ILP when registers are available and avoid overscheduling in high pressure situations.</li>
787</ol></li>
Chris Lattner3bdcda12010-10-04 03:58:12 +0000[diff] [blame]788<li>The tblgen type inference algorithm was rewritten to be more consistent and
789 diagnose more target bugs. If you have an out-of-tree backend, you may
790 find that it finds bugs in your target description. This support also
791 allows limited support for writing patterns for instructions that return
792 multiple results (e.g. a virtual register and a flag result). The
793 'parallel' modifier in tblgen was removed, you should use the new support
794 for multiple results instead.</li>
795<li>A new (experimental) "-rendermf" pass is available which renders a
796 MachineFunction into HTML, showing live ranges and other useful
797 details.</li>
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]798<li>The new SubRegIndex tablegen class allows subregisters to be indexed
799 symbolically instead of numerically. If your target uses subregisters you
800 will need to adapt to use SubRegIndex when you upgrade to 2.8.</li>
Chris Lattner3bdcda12010-10-04 03:58:12 +0000[diff] [blame]801<!-- SplitKit -->
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]802
Chris Lattner3bdcda12010-10-04 03:58:12 +0000[diff] [blame]803<li>The -fast-isel instruction selection path (used at -O0 on X86) was rewritten
804 to work bottom-up on basic blocks instead of top down. This makes it
805 slightly faster (because the MachineDCE pass is not needed any longer) and
806 allows it to generate better code in some cases.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]807
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]808</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]809</div>
810
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]811<!--=========================================================================-->
812<div class="doc_subsection">
813<a name="x86">X86-32 and X86-64 Target Improvements</a>
814</div>
815
816<div class="doc_text">
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]817<p>New features and major changes in the X86 target include:
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]818</p>
819
820<ul>
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]821<li>The X86 backend now supports holding X87 floating point stack values
822 in registers across basic blocks, dramatically improving performance of code
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]823 that uses long double, and when targeting CPUs that don't support SSE.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000[diff] [blame]824
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]825<li>The X86 backend now uses a SSEDomainFix pass to optimize SSE operations. On
826 Nehalem ("Core i7") and newer CPUs there is a 2 cycle latency penalty on
827 using a register in a different domain than where it was defined. This pass
828 optimizes away these stalls.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]829
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]830<li>The X86 backend now promotes 16-bit integer operations to 32-bits when
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]831 possible. This avoids 0x66 prefixes, which are slow on some
832 microarchitectures and bloat the code on all of them.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]833
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]834<li>The X86 backend now supports the Microsoft "thiscall" calling convention,
835 and a <a href="LangRef.html#callingconv">calling convention</a> to support
836 <a href="#GHC">ghc</a>.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]837
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]838<li>The X86 backend supports a new "llvm.x86.int" intrinsic, which maps onto
839 the X86 "int $42" and "int3" instructions.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]840
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]841<li>At the IR level, the &lt;2 x float&gt; datatype is now promoted and passed
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]842 around as a &lt;4 x float&gt; instead of being passed and returned as an MMX
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]843 vector. If you have a frontend that uses this, please pass and return a
844 &lt;2 x i32&gt; instead (using bitcasts).</li>
845
846<li>When printing .s files in verbose assembly mode (the default for clang -S),
847 the X86 backend now decodes X86 shuffle instructions and prints human
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]848 readable comments after the most inscrutable of them, e.g.:
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]849
850<pre>
851 insertps $113, %xmm3, %xmm0 <i># xmm0 = zero,xmm0[1,2],xmm3[1]</i>
852 unpcklps %xmm1, %xmm0 <i># xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]</i>
853 pshufd $1, %xmm1, %xmm1 <i># xmm1 = xmm1[1,0,0,0]</i>
854</pre>
855</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]856
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]857</ul>
858
Chris Lattner917cc712009-03-02 02:37:32 +0000[diff] [blame]859</div>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]860
861<!--=========================================================================-->
862<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]863<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]864</div>
865
866<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]867<p>New features of the ARM target include:
868</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]869
870<ul>
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]871<li>The ARM backend now optimizes tail calls into jumps.</li>
872<li>Scheduling is improved through the new list-hybrid scheduler as well
873 as through better modeling of structural hazards.</li>
874<li><a href="LangRef.html#int_fp16">Half float</a> instructions are now
875 supported.</li>
876<li>NEON support has been improved to model instructions which operate onto
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]877 multiple consecutive registers more aggressively. This avoids lots of
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]878 extraneous register copies.</li>
879<li>The ARM backend now uses a new "ARMGlobalMerge" pass, which merges several
880 global variables into one, saving extra address computation (all the global
881 variables can be accessed via same base address) and potentially reducing
882 register pressure.</li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]883
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]884<li>The ARM has received many minor improvements and tweaks which lead to
885substantially better performance in a wide range of different scenarios.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]886
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]887<li>The ARM NEON intrinsics have been substantially reworked to reduce
888 redundancy and improve code generation. Some of the major changes are:
889 <ol>
890 <li>
891 All of the NEON load and store intrinsics (llvm.arm.neon.vld* and
892 llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes
893 of the memory being accessed.
894 </li>
895 <li>
896 The llvm.arm.neon.vaba intrinsic (vector absolute difference and
897 accumulate) has been removed. This operation is now represented using
898 the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a
899 vector add.
900 </li>
901 <li>
902 The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]903 vector absolute difference with and without accumulation) have been removed.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]904 They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute
905 difference) followed by a vector zero-extend operation, and for vabal,
906 a vector add.
907 </li>
908 <li>
909 The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic
910 are now replaced by vector truncate operations.
911 </li>
912 <li>
913 The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been
914 removed. They are now represented as vector sign-extend (vmovls) and
915 zero-extend (vmovlu) operations.
916 </li>
917 <li>
918 The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and
919 llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have
920 been removed. They are replaced by vector add and vector subtract operations
921 where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either
922 sign-extended or zero-extended.
923 </li>
924 <li>
925 The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and
926 llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without
927 accumulation and subtraction) have been removed. These operations are now
928 represented as vector multiplications where the operands are either
929 sign-extended or zero-extended, followed by a vector add for vmlal or a
930 vector subtract for vmlsl. Note that the polynomial vector multiply
931 intrinsic, llvm.arm.neon.vmullp, remains unchanged.
932 </li>
933 </ol>
Bob Wilson5b2fb952010-09-13 17:37:55 +0000[diff] [blame]934</li>
Chris Lattner7714c912010-10-04 04:39:25 +0000[diff] [blame]935
Bob Wilsone8472772010-09-13 17:39:35 +0000[diff] [blame]936</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000[diff] [blame]937</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000[diff] [blame]938
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]939
940<!--=========================================================================-->
941<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]942<a name="changes">Major Changes and Removed Features</a>
943</div>
944
945<div class="doc_text">
946
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]947<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattner922d00f2010-07-21 15:57:40 +0000[diff] [blame]948on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]949from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]950
951<ul>
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]952<li>The build configuration machinery changed the output directory names. It
Duncan Sands30be9e42010-10-04 10:04:14 +0000[diff] [blame]953 wasn't clear to many people that a "Release-Asserts" build was a release build
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]954 without asserts. To make this more clear, "Release" does not include
955 assertions and "Release+Asserts" does (likewise, "Debug" and
956 "Debug+Asserts").</li>
957<li>The MSIL Backend was removed, it was unsupported and broken.</li>
958<li>The ABCD, SSI, and SCCVN passes were removed. These were not fully
959 functional and their behavior has been or will be subsumed by the
960 LazyValueInfo pass.</li>
961<li>The LLVM IR 'Union' feature was removed. While this is a desirable feature
962 for LLVM IR to support, the existing implementation was half baked and
963 barely useful. We'd really like anyone interested to resurrect the work and
964 finish it for a future release.</li>
965<li>If you're used to reading .ll files, you'll probably notice that .ll file
966 dumps don't produce #uses comments anymore. To get them, run a .bc file
967 through "llvm-dis --show-annotations".</li>
Chris Lattner11b66112010-10-04 02:42:39 +0000[diff] [blame]968<li>Target triples are now stored in a normalized form, and all inputs from
969 humans are expected to be normalized by Triple::normalize before being
970 stored in a module triple or passed to another library.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000[diff] [blame]971</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]972
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]973
974
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]975<p>In addition, many APIs have changed in this release. Some of the major LLVM
976API changes are:</p>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000[diff] [blame]977<ul>
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]978<li>LLVM 2.8 changes the internal order of operands in <a
979 href="http://llvm.org/doxygen/classllvm_1_1InvokeInst.html"><tt>InvokeInst</tt></a>
980 and <a href="http://llvm.org/doxygen/classllvm_1_1CallInst.html"><tt>CallInst</tt></a>.
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]981 To be portable across releases, please use the <tt>CallSite</tt> class and the
982 high-level accessors, such as <tt>getCalledValue</tt> and
983 <tt>setUnwindDest</tt>.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]984</li>
985<li>
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]986 You can no longer pass use_iterators directly to cast&lt;&gt; (and similar),
987 because these routines tend to perform costly dereference operations more
988 than once. You have to dereference the iterators yourself and pass them in.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]989</li>
990<li>
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]991 llvm.memcpy.*, llvm.memset.*, llvm.memmove.* intrinsics take an extra
992 parameter now ("i1 isVolatile"), totaling 5 parameters, and the pointer
993 operands are now address-space qualified.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]994 If you were creating these intrinsic calls and prototypes yourself (as opposed
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]995 to using Intrinsic::getDeclaration), you can use
Gabor Greif9f459132010-10-04 17:03:49 +0000[diff] [blame]996 UpgradeIntrinsicFunction/UpgradeIntrinsicCall to be portable across releases.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]997</li>
998<li>
999 SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode.
1000 Change your code to use
1001 SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)).
1002</li>
1003<li>
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]1004 The <tt>RegisterPass</tt> and <tt>RegisterAnalysisGroup</tt> templates are
1005 considered deprecated, but continue to function in LLVM 2.8. Clients are
1006 strongly advised to use the upcoming <tt>INITIALIZE_PASS()</tt> and
1007 <tt>INITIALIZE_AG_PASS()</tt> macros instead.
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]1008</li>
1009<li>
1010 The constructor for the Triple class no longer tries to understand odd triple
1011 specifications. Frontends should ensure that they only pass valid triples to
1012 LLVM. The Triple::normalize utility method has been added to help front-ends
1013 deal with funky triples.
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]1014</li>
1015
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]1016<li>
1017 Some APIs got renamed:
1018 <ul>
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]1019 <li>llvm_report_error -&gt; report_fatal_error</li>
1020 <li>llvm_install_error_handler -&gt; install_fatal_error_handler</li>
1021 <li>llvm::DwarfExceptionHandling -&gt; llvm::JITExceptionHandling</li>
1022 <li>VISIBILITY_HIDDEN -&gt; LLVM_LIBRARY_VISIBILITY</li>
Chris Lattner4eac9242010-10-02 22:44:15 +0000[diff] [blame]1023 </ul>
1024</li>
1025
Devang Patelb34dd132008-10-14 20:03:43 +0000[diff] [blame]1026</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1027
Chris Lattnerf6662f92008-10-13 17:57:36 +0000[diff] [blame]1028</div>
1029
1030
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1031<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1032<div class="doc_section">
1033 <a name="knownproblems">Known Problems</a>
1034</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1035<!-- *********************************************************************** -->
1036
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1037<div class="doc_text">
1038
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000[diff] [blame]1039<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000[diff] [blame]1040listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]1041href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1042there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1043
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1044</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1045
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1046<!-- ======================================================================= -->
1047<div class="doc_subsection">
1048 <a name="experimental">Experimental features included with this release</a>
1049</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1050
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1051<div class="doc_text">
1052
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]1053<p>The following components of this LLVM release are either untested, known to
1054be broken or unreliable, or are in early development. These components should
1055not be relied on, and bugs should not be filed against them, but they may be
1056useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1057components, please contact us on the <a
1058href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1059
1060<ul>
Chris Lattnerbb117712010-10-04 01:29:06 +0000[diff] [blame]1061<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PIC16, SystemZ
1062 and XCore backends are experimental.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000[diff] [blame]1063<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
1064 other than darwin-i386 and darwin-x86_64.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]1065</ul>
1066
1067</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1068
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1069<!-- ======================================================================= -->
1070<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1071 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1072</div>
1073
1074<div class="doc_text">
1075
1076<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]1077 <li>The X86 backend does not yet support
1078 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
1079 floating point stack</a>. It supports the 'f' and 't' constraints, but not
1080 'u'.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]1081 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1082 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]1083 runtime currently due to lack of support for the 'u' inline assembly
1084 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1085 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000[diff] [blame]1086 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]1087 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1088</ul>
1089
1090</div>
1091
1092<!-- ======================================================================= -->
1093<div class="doc_subsection">
1094 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1095</div>
1096
1097<div class="doc_text">
1098
1099<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]1100<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1101compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1102</ul>
1103
1104</div>
1105
1106<!-- ======================================================================= -->
1107<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1108 <a name="arm-be">Known problems with the ARM back-end</a>
1109</div>
1110
1111<div class="doc_text">
1112
1113<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1114<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]1115processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]1116results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1117<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1118</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1119</ul>
1120
1121</div>
1122
1123<!-- ======================================================================= -->
1124<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1125 <a name="sparc-be">Known problems with the SPARC back-end</a>
1126</div>
1127
1128<div class="doc_text">
1129
1130<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000[diff] [blame]1131<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]1132 support the 64-bit SPARC ABI (-m64).</li>
1133</ul>
1134
1135</div>
1136
1137<!-- ======================================================================= -->
1138<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1139 <a name="mips-be">Known problems with the MIPS back-end</a>
1140</div>
1141
1142<div class="doc_text">
1143
1144<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000[diff] [blame]1145<li>64-bit MIPS targets are not supported yet.</li>
1146</ul>
1147
1148</div>
1149
1150<!-- ======================================================================= -->
1151<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1152 <a name="alpha-be">Known problems with the Alpha back-end</a>
1153</div>
1154
1155<div class="doc_text">
1156
1157<ul>
1158
1159<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1160appropriate nops inserted to ensure restartability.</li>
1161
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1162</ul>
1163</div>
1164
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1165<!-- ======================================================================= -->
1166<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]1167 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1168</div>
1169
1170<div class="doc_text">
1171
Chris Lattner3016ee92010-09-29 05:34:42 +0000[diff] [blame]1172<p>The C backend has numerous problems and is not being actively maintained.
1173Depending on it for anything serious is not advised.</p>
1174
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1175<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]1176<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1177 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]1178<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1179 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000[diff] [blame]1180 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]1181<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000[diff] [blame]1182<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]1183</ul>
1184
1185</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]1186
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1187
1188<!-- ======================================================================= -->
1189<div class="doc_subsection">
Chris Lattner3016ee92010-09-29 05:34:42 +0000[diff] [blame]1190 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1191</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]1192
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1193<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]1194
Chris Lattner3016ee92010-09-29 05:34:42 +0000[diff] [blame]1195<p>llvm-gcc is generally very stable for the C family of languages. The only
1196 major language feature of GCC not supported by llvm-gcc is the
1197 <tt>__builtin_apply</tt> family of builtins. However, some extensions
1198 are only supported on some targets. For example, trampolines are only
1199 supported on some targets (these are used when you take the address of a
1200 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1201
Chris Lattner3016ee92010-09-29 05:34:42 +0000[diff] [blame]1202<p>Fortran support generally works, but there are still several unresolved bugs
1203 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1204 tools/gfortran component for details. Note that llvm-gcc is missing major
1205 Fortran performance work in the frontend and library that went into GCC after
1206 4.2. If you are interested in Fortran, we recommend that you consider using
1207 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1208
Duncan Sands3af96332010-10-04 10:06:56 +0000[diff] [blame]1209<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
1210actively maintained. If you are interested in Ada, we recommend that you
1211consider using <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]1212</div>
1213
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1214<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1215<div class="doc_section">
1216 <a name="additionalinfo">Additional Information</a>
1217</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1218<!-- *********************************************************************** -->
1219
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1220<div class="doc_text">
1221
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]1222<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1223href="http://llvm.org">LLVM web page</a>, in particular in the <a
1224href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]1225contains versions of the API documentation which is up-to-date with the
1226Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]1227You can access versions of these documents specific to this release by going
1228into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1229
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1230<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]1231us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]1232lists</a>.</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
1236<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1237
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1238<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1239<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]1240 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1241 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1242 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1243 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]1244
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]1245 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1246 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]1247</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]1248
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1249</body>
1250</html>