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Chris Lattner0d364302011-03-10 07:43:44 +00008 <title>LLVM 2.9 Release Notes</title>
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10<body>
Chris Lattner3d482502003-10-02 04:57:28 +000011
Chris Lattner0d364302011-03-10 07:43:44 +000012<div class="doc_title">LLVM 2.9 Release Notes</div>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +000013
Chris Lattnerc871bac2010-03-17 04:02:39 +000014<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greif27b166352010-04-22 10:21:43 +000015 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattnerc871bac2010-03-17 04:02:39 +000016
Chris Lattner3d482502003-10-02 04:57:28 +000017<ol>
Misha Brukman80731b92003-11-22 00:38:41 +000018 <li><a href="#intro">Introduction</a></li>
Chris Lattnerf5cd9862008-10-13 18:01:01 +000019 <li><a href="#subproj">Sub-project Status Update</a></li>
Chris Lattner0d364302011-03-10 07:43:44 +000020 <li><a href="#externalproj">External Projects Using LLVM 2.9</a></li>
21 <li><a href="#whatsnew">What's New in LLVM 2.9?</a></li>
Chris Lattner77a51732004-04-30 22:17:12 +000022 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Dan Gohmanad888912008-10-14 16:23:02 +000023 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +000024 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +000025</ol>
26
Chris Lattner020e1fc2004-05-23 21:07:27 +000027<div class="doc_author">
Dan Gohmanad888912008-10-14 16:23:02 +000028 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman80731b92003-11-22 00:38:41 +000029</div>
Chris Lattner3d482502003-10-02 04:57:28 +000030
Chris Lattner0d364302011-03-10 07:43:44 +000031<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.9
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000032release.<br>
33You may prefer the
Chris Lattner0d364302011-03-10 07:43:44 +000034<a href="http://llvm.org/releases/2.8/docs/ReleaseNotes.html">LLVM 2.8
Dan Gohman62af9d22010-05-03 23:51:05 +000035Release Notes</a>.</h1>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000036
Chris Lattner3d482502003-10-02 04:57:28 +000037<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +000038<div class="doc_section">
39 <a name="intro">Introduction</a>
40</div>
Chris Lattner3d482502003-10-02 04:57:28 +000041<!-- *********************************************************************** -->
42
Misha Brukman80731b92003-11-22 00:38:41 +000043<div class="doc_text">
44
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000045<p>This document contains the release notes for the LLVM Compiler
Chris Lattner0d364302011-03-10 07:43:44 +000046Infrastructure, release 2.9. Here we describe the status of LLVM, including
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000047major improvements from the previous release and significant known problems.
Mikhail Glushenkov25422542009-03-01 18:09:47 +000048All LLVM releases may be downloaded from the <a
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000049href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner62495762003-10-02 16:38:05 +000050
Chris Lattnerb5bb5972004-12-07 08:04:13 +000051<p>For more information about LLVM, including information about the latest
Chris Lattnera69595e2005-10-29 07:07:09 +000052release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattnere7525b52003-10-07 21:38:31 +000053web site</a>. If you have questions or comments, the <a
Chris Lattner0b1c9a52010-03-17 04:41:49 +000054href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
55Mailing List</a> is a good place to send them.</p>
Chris Lattner3d482502003-10-02 04:57:28 +000056
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +000057<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner0a1fd102007-09-21 03:54:09 +000058main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif355f81c2008-10-14 11:00:32 +000059current one. To see the release notes for a specific release, please see the
Chris Lattner0a1fd102007-09-21 03:54:09 +000060<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman80731b92003-11-22 00:38:41 +000061
62</div>
Chris Lattner0d364302011-03-10 07:43:44 +000063
Chris Lattneraa61f412009-10-13 17:48:04 +000064<!--
65Almost dead code.
Chris Lattner0d364302011-03-10 07:43:44 +000066 lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.0.
Chris Lattneraa61f412009-10-13 17:48:04 +000067-->
68
69
Chris Lattner0d364302011-03-10 07:43:44 +000070<!-- Features that need text if they're finished for 3.0:
Chris Lattnera67df2d2010-04-22 06:28:20 +000071 combiner-aa?
Chris Lattneraa61f412009-10-13 17:48:04 +000072 strong phi elim
Chris Lattneraa61f412009-10-13 17:48:04 +000073 loop dependence analysis
Chris Lattner342f9572010-09-29 05:30:03 +000074 CorrelatedValuePropagation
Chris Lattner2b8a52e2008-02-10 07:46:44 +000075 -->
Chris Lattner342f9572010-09-29 05:30:03 +000076
Chris Lattnerf5cd9862008-10-13 18:01:01 +000077<!-- *********************************************************************** -->
78<div class="doc_section">
79 <a name="subproj">Sub-project Status Update</a>
Chris Lattner625a3d82008-06-08 21:34:41 +000080</div>
Chris Lattnerf5cd9862008-10-13 18:01:01 +000081<!-- *********************************************************************** -->
Chris Lattner625a3d82008-06-08 21:34:41 +000082
83<div class="doc_text">
Chris Lattnerc75fd522008-06-08 21:58:17 +000084<p>
Chris Lattner0d364302011-03-10 07:43:44 +000085The LLVM 2.9 distribution currently consists of code from the core LLVM
Chris Lattneraa61f412009-10-13 17:48:04 +000086repository (which roughly includes the LLVM optimizers, code generators
87and supporting tools), the Clang repository and the llvm-gcc repository. In
88addition to this code, the LLVM Project includes other sub-projects that are in
89development. Here we include updates on these subprojects.
Bill Wendlingf170d2e2009-03-02 04:28:57 +000090</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +000091
Chris Lattnerc75fd522008-06-08 21:58:17 +000092</div>
93
Chris Lattnerf5cd9862008-10-13 18:01:01 +000094
Chris Lattnerc75fd522008-06-08 21:58:17 +000095<!--=========================================================================-->
Chris Lattnerf5cd9862008-10-13 18:01:01 +000096<div class="doc_subsection">
Chris Lattner44c09cd2008-10-13 18:11:54 +000097<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +000098</div>
99
100<div class="doc_text">
101
Chris Lattner5de7f6e2010-04-26 17:42:18 +0000102<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
103C++, and Objective-C languages. Clang aims to provide a better user experience
104through expressive diagnostics, a high level of conformance to language
105standards, fast compilation, and low memory use. Like LLVM, Clang provides a
106modular, library-based architecture that makes it suitable for creating or
107integrating with other development tools. Clang is considered a
Chris Lattner342f9572010-09-29 05:30:03 +0000108production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
109(32- and 64-bit), and for darwin-arm targets.</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000110
Chris Lattnerfd97b882011-04-05 07:19:28 +0000111<p>In the LLVM 2.9 time-frame, the Clang team has made many improvements in C,
112C++ and Objective-C support. C++ support is now generally rock solid, has
113been exercised on a broad variety of code, and has several new C++'0x features
114implemented (such as rvalue references and variadic templates). LLVM 2.9 has
115also brought in a large range of bug fixes and minor features (e.g. __label__
116support), and is much more compatible with the Linux Kernel.</p>
117
118<p>If Clang rejects your code that is built with another compiler, please take a
119look at the <a href="http://clang.llvm.org/compatibility.html">language
120compatibility</a> guide to make sure the issue isn't intentional or a known
121issue.
122</p>
Bill Wendlingef362462008-10-27 09:27:33 +0000123
Chris Lattner0d364302011-03-10 07:43:44 +0000124<ul>
125</ul>
Chris Lattner44c09cd2008-10-13 18:11:54 +0000126</div>
127
128<!--=========================================================================-->
129<div class="doc_subsection">
Duncan Sands1cd78982011-04-04 11:09:08 +0000130<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
Chris Lattneraa61f412009-10-13 17:48:04 +0000131</div>
132
133<div class="doc_text">
134<p>
Duncan Sands1cd78982011-04-04 11:09:08 +0000135<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
136<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
137optimizers and code generators with LLVM's.
138Currently it requires a patched version of gcc-4.5.
139The plugin can target the x86-32 and x86-64 processor families and has been
140used successfully on the Darwin, FreeBSD and Linux platforms.
141The Ada, C, C++ and Fortran languages work well.
142The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is
143not known whether the compiled code actually works or not!
Duncan Sands92452b92010-04-02 09:23:15 +0000144</p>
145
146<p>
Chris Lattner0d364302011-03-10 07:43:44 +0000147The 2.9 release has the following notable changes:
Duncan Sands7f9a0dc2010-09-30 17:37:34 +0000148<ul>
Duncan Sands1cd78982011-04-04 11:09:08 +0000149<li>The plugin is much more stable when compiling Fortran.</li>
150<li>Inline asm where an asm output is tied to an input of a different size is
151now supported in many more cases.</li>
152<li>Basic support for the __float128 type was added. It is now possible to
153generate LLVM IR from programs using __float128 but code generation does not
154work yet.</li>
155<li>Compiling Java programs no longer systematically crashes the plugin.</li>
Duncan Sands7f9a0dc2010-09-30 17:37:34 +0000156</ul>
Chris Lattneraa61f412009-10-13 17:48:04 +0000157
158</div>
159
Chris Lattner120804a2010-10-03 23:49:06 +0000160<!--=========================================================================-->
161<div class="doc_subsection">
Chris Lattner120804a2010-10-03 23:49:06 +0000162<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
163</div>
164
165<div class="doc_text">
166<p>
167The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
168is a simple library that provides an implementation of the low-level
169target-specific hooks required by code generation and other runtime components.
170For example, when compiling for a 32-bit target, converting a double to a 64-bit
171unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
172function. The compiler-rt library provides highly optimized implementations of
173this and other low-level routines (some are 3x faster than the equivalent
174libgcc routines).</p>
175
176<p>
177All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner0d364302011-03-10 07:43:44 +0000178License, a "BSD-style" license.
179
Chris Lattnerfd97b882011-04-05 07:19:28 +0000180compiler_rt is now dual licensed under MIT and UIUC license
181
182Several minor changes for better ARM support.
Chris Lattner0d364302011-03-10 07:43:44 +0000183
184New in LLVM 2.9, UPDATE</p>
Chris Lattner120804a2010-10-03 23:49:06 +0000185
186</div>
Chris Lattneraa61f412009-10-13 17:48:04 +0000187
188<!--=========================================================================-->
189<div class="doc_subsection">
Chris Lattner342f9572010-09-29 05:30:03 +0000190<a name="lldb">LLDB: Low Level Debugger</a>
191</div>
192
193<div class="doc_text">
194<p>
Chris Lattner120804a2010-10-03 23:49:06 +0000195<a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
196umbrella of projects. LLDB is a next generation, high-performance debugger. It
197is built as a set of reusable components which highly leverage existing
198libraries in the larger LLVM Project, such as the Clang expression parser, the
199LLVM disassembler and the LLVM JIT.</p>
Chris Lattner342f9572010-09-29 05:30:03 +0000200
201<p>
Chris Lattner0d364302011-03-10 07:43:44 +0000202LLDB is in early development and not included as part of the LLVM 2.9 release,
Chris Lattner0d364302011-03-10 07:43:44 +0000203
Chris Lattnerfd97b882011-04-05 07:19:28 +0000204
205
Chris Lattner0d364302011-03-10 07:43:44 +0000206<!--
Chris Lattner120804a2010-10-03 23:49:06 +0000207but is mature enough to support basic debugging scenarios on Mac OS X in C,
208Objective-C and C++. We'd really like help extending and expanding LLDB to
Chris Lattner0d364302011-03-10 07:43:44 +0000209support new platforms, new languages, new architectures, and new features.-->
Chris Lattner342f9572010-09-29 05:30:03 +0000210</p>
211
212</div>
213
214<!--=========================================================================-->
215<div class="doc_subsection">
216<a name="libc++">libc++: C++ Standard Library</a>
217</div>
218
219<div class="doc_text">
220<p>
Tobias Grosser436bc5f2010-10-06 21:07:30 +0000221<a href="http://libcxx.llvm.org/">libc++</a> is another new member of the LLVM
Chris Lattner120804a2010-10-03 23:49:06 +0000222family. It is an implementation of the C++ standard library, written from the
223ground up to specifically target the forthcoming C++'0X standard and focus on
224delivering great performance.</p>
Chris Lattner342f9572010-09-29 05:30:03 +0000225
226<p>
Chris Lattner0d364302011-03-10 07:43:44 +0000227As of the LLVM 2.9 release, UPDATE!
228
Chris Lattnerfd97b882011-04-05 07:19:28 +0000229libc++ is now dual licensed under MIT and UIUC license
230
Chris Lattner0d364302011-03-10 07:43:44 +0000231<!--libc++ is virtually feature complete, but would
Chris Lattner120804a2010-10-03 23:49:06 +0000232benefit from more testing and better integration with Clang++. It is also
Chris Lattner0d364302011-03-10 07:43:44 +0000233looking forward to the C++ committee finalizing the C++'0x standard.-->
Chris Lattner342f9572010-09-29 05:30:03 +0000234</p>
235
236</div>
237
Chris Lattneraa61f412009-10-13 17:48:04 +0000238
Daniel Dunbar8fbd8aa2010-10-04 17:39:47 +0000239
240<!--=========================================================================-->
241<div class="doc_subsection">
242<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
243</div>
244
245<div class="doc_text">
246<p>
247<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
248programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
249through the application and records state transitions that lead to fault
250states. This allows it to construct testcases that lead to faults and can even
251be used to verify some algorithms.
252</p>
253
Chris Lattner0d364302011-03-10 07:43:44 +0000254<p>UPDATE!</p>
Daniel Dunbar8fbd8aa2010-10-04 17:39:47 +0000255
256</div>
257
258
Chris Lattner53e06f92009-02-26 22:33:38 +0000259<!-- *********************************************************************** -->
260<div class="doc_section">
Chris Lattner0d364302011-03-10 07:43:44 +0000261 <a name="externalproj">External Open Source Projects Using LLVM 2.9</a>
Chris Lattner53e06f92009-02-26 22:33:38 +0000262</div>
263<!-- *********************************************************************** -->
264
Chris Lattneraa61f412009-10-13 17:48:04 +0000265<div class="doc_text">
266
267<p>An exciting aspect of LLVM is that it is used as an enabling technology for
268 a lot of other language and tools projects. This section lists some of the
Chris Lattner0d364302011-03-10 07:43:44 +0000269 projects that have already been updated to work with LLVM 2.9.</p>
Chris Lattnerdf85c892010-04-26 17:38:10 +0000270</div>
271
Chris Lattner120804a2010-10-03 23:49:06 +0000272
273
Chris Lattnerca7c8962010-10-01 06:34:49 +0000274
Chris Lattnerc75fd522008-06-08 21:58:17 +0000275<!-- *********************************************************************** -->
276<div class="doc_section">
Chris Lattner0d364302011-03-10 07:43:44 +0000277 <a name="whatsnew">What's New in LLVM 2.9?</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000278</div>
279<!-- *********************************************************************** -->
280
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000281<div class="doc_text">
282
Chris Lattneraa61f412009-10-13 17:48:04 +0000283<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000284minor improvements. Some of the major improvements and new features are listed
285in this section.
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000286</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000287
Chris Lattnera67df2d2010-04-22 06:28:20 +0000288</div>
289
290<!--=========================================================================-->
291<div class="doc_subsection">
Chris Lattnercdc44ed2008-02-06 18:00:06 +0000292<a name="majorfeatures">Major New Features</a>
293</div>
294
295<div class="doc_text">
296
Chris Lattner0d364302011-03-10 07:43:44 +0000297<p>LLVM 2.9 includes several major new capabilities:</p>
Chris Lattner97beb512007-05-14 06:56:09 +0000298
299<ul>
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000300<li><pre>
Chris Lattnerfd97b882011-04-05 07:19:28 +0000301 last release for llvm-gcc
302TBAA
303Triple::normalize is new, llvm triples are always stored in normalized form internally.
304
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000305Triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32 instead.
306
Chris Lattnerfd97b882011-04-05 07:19:28 +0000307MC Assembler: X86 now generates much better diagnostics for common errors,
308 is much faster at matching instructions, is much more bug-compatible with
309 the GAS assembler, and is now generally useful for a broad range of X86
310 assembly.
311
312New Nvidia PTX backend, not generally useful in 2.9 though.
313
314Much better debug info generated, particularly in optimized code situations.
315
316ARM Fast ISel
317
318ELF MC support
319
320X86: Reimplemented all of MMX to introduce a new LLVM IR x86_mmx type. Now
321 random types like &lt;2 x i32&gt; are not iseld to mmx without emms.
322
323Some basic <a href="CodeGenerator.html#mc">internals documentation</a> for MC.
324
325MC Assembler support for .file and .loc.
326
327
328inline asm multiple alternative constraint support.
329
330LoopIdiom: memset/memcpy formation
331
332
333X86 support for FS/GS relative loads and stores using address space 256/257 are
334 reliable now.
335
336ARM: New code placement pass.
337
338
339PointerTracking has been removed from mainline, moved to ClamAV.
340
341EarlyCSE pass.
342
343
344ARM: Improved code generation for Cortex-A8 and Cortex-A9 CPUs.
345
346Scheduler now models operand latency and pipeline forwarding.
347
348Major regalloc rewrite, not on by default for 2.9.
349MC assembler support for 3dNow! and 3DNowA instructions.
350
351LoopIndexSplit pass was removed, unmaintained.
352
353
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000354Win32 PE-COFF support in the MC assembler has made a lot of progress in the 2.9
Chris Lattnerfd97b882011-04-05 07:19:28 +0000355 timeframe, but is still not generally useful. Please see
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000356 "http://llvm.org/bugs/showdependencytree.cgi?id=9100&amp;hide_resolved=1" for open bugs?
Chris Lattnerfd97b882011-04-05 07:19:28 +0000357
358New <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a> infrastructure
359 for region-based optimizations.
360
361MicroBlaze: major updates for aggressive delay slot filler, MC-based assembly
362 printing, assembly instruction parsing, ELF .o file emission, and MC
363 instruction disassembler.
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000364</pre></li>
Chris Lattner458e79f2008-02-10 08:18:42 +0000365</ul>
Chris Lattnerfd97b882011-04-05 07:19:28 +0000366
367Still todo: [101025-110228]
Chris Lattner10a3cc42010-03-17 06:41:58 +0000368
Chris Lattner97beb512007-05-14 06:56:09 +0000369</div>
370
Chris Lattner0a1fd102007-09-21 03:54:09 +0000371<!--=========================================================================-->
372<div class="doc_subsection">
Chris Lattnerd1094e02009-03-02 02:37:32 +0000373<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000374</div>
375
376<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000377<p>LLVM IR has several new features for better support of new targets and that
378expose new optimization opportunities:</p>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000379
Chris Lattnerb7112222008-06-05 06:25:56 +0000380<ul>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000381</ul>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +0000382
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000383</div>
384
385<!--=========================================================================-->
386<div class="doc_subsection">
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000387<a name="optimizer">Optimizer Improvements</a>
388</div>
389
390<div class="doc_text">
391
Chris Lattneraa61f412009-10-13 17:48:04 +0000392<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattner25879d72008-10-13 21:50:36 +0000393release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000394
395<ul>
Rafael Espindola01fb4b02011-03-18 04:07:44 +0000396 <li>TBAA.</li>
397 <li>LTO has been improved to use MC for parsing inline asm and now
398 can build large programs like Firefox 4 on both OS X and Linux.</li>
Chris Lattnerfcc65a72010-10-04 02:42:39 +0000399</ul>
400
401<!--
402<p>In addition to these features that are done in 2.8, there is preliminary
403 support in the release for Type Based Alias Analysis
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000404 Preliminary work on TBAA but not usable in 2.8.
405 New CorrelatedValuePropagation pass, not on by default in 2.8 yet.
Chris Lattnerfcc65a72010-10-04 02:42:39 +0000406-->
Chris Lattnerd1094e02009-03-02 02:37:32 +0000407
Chris Lattneraa61f412009-10-13 17:48:04 +0000408</div>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000409
Chris Lattner7795ea92008-06-08 02:45:07 +0000410<!--=========================================================================-->
411<div class="doc_subsection">
Chris Lattnerf25bc192010-09-30 16:31:33 +0000412<a name="mc">MC Level Improvements</a>
413</div>
414
415<div class="doc_text">
416<p>
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000417The LLVM Machine Code (aka MC) subsystem was created to solve a number
Chris Lattnerf25bc192010-09-30 16:31:33 +0000418of problems in the realm of assembly, disassembly, object file format handling,
419and a number of other related areas that CPU instruction-set level tools work
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000420in.</p>
421
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000422<ul>
Rafael Espindola01fb4b02011-03-18 04:07:44 +0000423 <li>MC is now used by default for ELF systems on x86 and
424 x86-64.</li>
425 <li>MC supports and CodeGen uses the <tt>.loc</tt> directives for
426 producing line number debug info. This produces more compact line
427 tables.</li>
428 <li>MC supports the <tt>.cfi_*</tt> directives for producing DWARF
429 frame information, but it is still not used by CodeGen by default.</li>
430 <li>COFF support?</li>
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000431</ul>
432
433<p>For more information, please see the <a
Chris Lattnerf25bc192010-09-30 16:31:33 +0000434href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
435LLVM MC Project Blog Post</a>.
436</p>
437
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000438</div>
Chris Lattnerf25bc192010-09-30 16:31:33 +0000439
Chris Lattnerf25bc192010-09-30 16:31:33 +0000440<!--=========================================================================-->
441<div class="doc_subsection">
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000442<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner7795ea92008-06-08 02:45:07 +0000443</div>
444
445<div class="doc_text">
446
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000447<p>We have put a significant amount of work into the code generator
448infrastructure, which allows us to implement more aggressive algorithms and make
449it run faster:</p>
Chris Lattner7795ea92008-06-08 02:45:07 +0000450
451<ul>
Chris Lattner9fd1e922010-10-04 03:58:12 +0000452<!-- SplitKit -->
Chris Lattner0d364302011-03-10 07:43:44 +0000453FastISel for ARM.
Chris Lattner0a1fd102007-09-21 03:54:09 +0000454</ul>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000455</div>
456
Chris Lattnerd1094e02009-03-02 02:37:32 +0000457<!--=========================================================================-->
458<div class="doc_subsection">
459<a name="x86">X86-32 and X86-64 Target Improvements</a>
460</div>
461
462<div class="doc_text">
Chris Lattnerd3f45c82010-10-04 04:39:25 +0000463<p>New features and major changes in the X86 target include:
Chris Lattnerd1094e02009-03-02 02:37:32 +0000464</p>
465
466<ul>
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000467 <li>Several bugs have been fixed for Windows x64 code generator.</li>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000468</ul>
469
Chris Lattnerd1094e02009-03-02 02:37:32 +0000470</div>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000471
472<!--=========================================================================-->
473<div class="doc_subsection">
Chris Lattneraa61f412009-10-13 17:48:04 +0000474<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000475</div>
476
477<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000478<p>New features of the ARM target include:
479</p>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000480
481<ul>
Bob Wilsone44f2982010-09-13 17:39:35 +0000482</ul>
Chris Lattneraa61f412009-10-13 17:48:04 +0000483</div>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000484
Chris Lattner6cb64032008-06-05 08:02:49 +0000485
486<!--=========================================================================-->
487<div class="doc_subsection">
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000488<a name="changes">Major Changes and Removed Features</a>
489</div>
490
491<div class="doc_text">
492
Chris Lattner934e2d42008-10-13 22:06:31 +0000493<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattner0d364302011-03-10 07:43:44 +0000494on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
Chris Lattner934e2d42008-10-13 22:06:31 +0000495from the previous release.</p>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000496
497<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000498</ul>
Chris Lattner934e2d42008-10-13 22:06:31 +0000499
Chris Lattnera7f45cf2010-10-04 01:29:06 +0000500
501
Chris Lattner934e2d42008-10-13 22:06:31 +0000502<p>In addition, many APIs have changed in this release. Some of the major LLVM
503API changes are:</p>
Chris Lattner934e2d42008-10-13 22:06:31 +0000504<ul>
Devang Pateldbf83832008-10-14 20:03:43 +0000505</ul>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000506
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000507</div>
508
Daniel Dunbarf70898a2010-10-04 20:11:41 +0000509<!--=========================================================================-->
510<div class="doc_subsection">
511<a name="devtree_changes">Development Infrastructure Changes</a>
512</div>
513
514<div class="doc_text">
515
516<p>This section lists changes to the LLVM development infrastructure. This
517mostly impacts users who actively work on LLVM or follow development on
518mainline, but may also impact users who leverage the LLVM build infrastructure
519or are interested in LLVM qualification.</p>
520
521<ul>
Daniel Dunbarf70898a2010-10-04 20:11:41 +0000522</ul>
523</div>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000524
Chris Lattner3d482502003-10-02 04:57:28 +0000525<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000526<div class="doc_section">
527 <a name="knownproblems">Known Problems</a>
528</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000529<!-- *********************************************************************** -->
530
Misha Brukman80731b92003-11-22 00:38:41 +0000531<div class="doc_text">
532
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000533<p>This section contains significant known problems with the LLVM system,
Chris Lattner2a092392008-11-10 05:40:34 +0000534listed by component. If you run into a problem, please check the <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000535href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000536there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000537
Misha Brukman80731b92003-11-22 00:38:41 +0000538</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000539
Chris Lattnerb911de42004-03-14 02:03:02 +0000540<!-- ======================================================================= -->
541<div class="doc_subsection">
542 <a name="experimental">Experimental features included with this release</a>
543</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000544
Chris Lattnerb911de42004-03-14 02:03:02 +0000545<div class="doc_text">
546
Misha Brukmanfa50a222004-05-12 21:46:05 +0000547<p>The following components of this LLVM release are either untested, known to
548be broken or unreliable, or are in early development. These components should
549not be relied on, and bugs should not be filed against them, but they may be
550useful to some people. In particular, if you would like to work on one of these
Chris Lattnere38ac152008-02-12 06:29:45 +0000551components, please contact us on the <a
552href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerb911de42004-03-14 02:03:02 +0000553
554<ul>
Chris Lattner0d364302011-03-10 07:43:44 +0000555<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ
Chris Lattnera7f45cf2010-10-04 01:29:06 +0000556 and XCore backends are experimental.</li>
Chris Lattnerbf1cf672010-10-02 21:59:30 +0000557<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
Chris Lattner0d364302011-03-10 07:43:44 +0000558 other than darwin-i386 and darwin-x86_64. FIXME: Not true on ELF anymore?</li>
559
Chris Lattnerb911de42004-03-14 02:03:02 +0000560</ul>
561
562</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000563
Misha Brukman80731b92003-11-22 00:38:41 +0000564<!-- ======================================================================= -->
565<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000566 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswell3bdbd302005-11-08 21:11:33 +0000567</div>
568
569<div class="doc_text">
570
571<ul>
Anton Korobeynikov486c7d32008-06-08 10:24:13 +0000572 <li>The X86 backend does not yet support
573 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
574 floating point stack</a>. It supports the 'f' and 't' constraints, but not
575 'u'.</li>
Dan Gohman721b3722008-06-08 23:05:11 +0000576 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattnera67df2d2010-04-22 06:28:20 +0000577 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman721b3722008-06-08 23:05:11 +0000578 argument constructs on X86-64 by lowering them manually.</li>
NAKAMURA Takumi8d89b8e2011-04-05 08:24:22 +0000579 <li>Windows x64 (aka Win64) code generator has a few issues.
580 <ul>
581 <li>llvm-gcc cannot build the mingw-w64 runtime currently
582 due to lack of support for the 'u' inline assembly
583 constraint and for X87 floating point inline assembly.</li>
584 <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt>
585 due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
586 It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
587 <li>Miss-aligned MOVDQA might crash your program. It is due to
588 <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>,
589 lack of handling aligned internal globals.</li>
590 </ul>
591 </li>
592
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000593</ul>
594
595</div>
596
597<!-- ======================================================================= -->
598<div class="doc_subsection">
599 <a name="ppc-be">Known problems with the PowerPC back-end</a>
600</div>
601
602<div class="doc_text">
603
604<ul>
Nicolas Geoffray77d99502007-05-15 09:21:28 +0000605<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattnerbee7b322007-05-23 04:39:32 +0000606compilation, and lacks support for debug information.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000607</ul>
608
609</div>
610
611<!-- ======================================================================= -->
612<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000613 <a name="arm-be">Known problems with the ARM back-end</a>
614</div>
615
616<div class="doc_text">
617
618<ul>
Chris Lattnerbee7b322007-05-23 04:39:32 +0000619<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands47fc0a22007-09-26 15:59:54 +0000620processors, thumb programs can crash or produce wrong
Chris Lattnerbee7b322007-05-23 04:39:32 +0000621results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellea03c9d2009-03-02 15:28:15 +0000622<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattner97beb512007-05-14 06:56:09 +0000623</li>
Chris Lattner97beb512007-05-14 06:56:09 +0000624</ul>
625
626</div>
627
628<!-- ======================================================================= -->
629<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000630 <a name="sparc-be">Known problems with the SPARC back-end</a>
631</div>
632
633<div class="doc_text">
634
635<ul>
John Criswellea03c9d2009-03-02 15:28:15 +0000636<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000637 support the 64-bit SPARC ABI (-m64).</li>
638</ul>
639
640</div>
641
642<!-- ======================================================================= -->
643<div class="doc_subsection">
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000644 <a name="mips-be">Known problems with the MIPS back-end</a>
645</div>
646
647<div class="doc_text">
648
649<ul>
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000650<li>64-bit MIPS targets are not supported yet.</li>
651</ul>
652
653</div>
654
655<!-- ======================================================================= -->
656<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000657 <a name="alpha-be">Known problems with the Alpha back-end</a>
658</div>
659
660<div class="doc_text">
661
662<ul>
663
664<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
665appropriate nops inserted to ensure restartability.</li>
666
John Criswell3bdbd302005-11-08 21:11:33 +0000667</ul>
668</div>
669
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000670<!-- ======================================================================= -->
671<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000672 <a name="c-be">Known problems with the C back-end</a>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000673</div>
674
675<div class="doc_text">
676
Chris Lattner086d2692010-09-29 05:34:42 +0000677<p>The C backend has numerous problems and is not being actively maintained.
678Depending on it for anything serious is not advised.</p>
679
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000680<ul>
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000681<li><a href="http://llvm.org/PR802">The C backend has only basic support for
682 inline assembly code</a>.</li>
Chris Lattner8e061162007-09-26 06:01:35 +0000683<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
684 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif75b2f762009-03-02 12:02:51 +0000685 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandse09506a2008-02-10 13:40:55 +0000686<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands3aa36732009-02-25 11:51:54 +0000687<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000688</ul>
689
690</div>
John Criswell3bdbd302005-11-08 21:11:33 +0000691
Misha Brukman80731b92003-11-22 00:38:41 +0000692
693<!-- ======================================================================= -->
694<div class="doc_subsection">
Chris Lattner086d2692010-09-29 05:34:42 +0000695 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000696</div>
Chris Lattner178f3db2003-10-02 05:07:23 +0000697
Misha Brukman80731b92003-11-22 00:38:41 +0000698<div class="doc_text">
Chris Lattner72a269f2006-03-03 00:34:26 +0000699
Chris Lattner086d2692010-09-29 05:34:42 +0000700<p>llvm-gcc is generally very stable for the C family of languages. The only
701 major language feature of GCC not supported by llvm-gcc is the
702 <tt>__builtin_apply</tt> family of builtins. However, some extensions
703 are only supported on some targets. For example, trampolines are only
704 supported on some targets (these are used when you take the address of a
705 nested function).</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000706
Chris Lattner086d2692010-09-29 05:34:42 +0000707<p>Fortran support generally works, but there are still several unresolved bugs
708 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
709 tools/gfortran component for details. Note that llvm-gcc is missing major
710 Fortran performance work in the frontend and library that went into GCC after
711 4.2. If you are interested in Fortran, we recommend that you consider using
712 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000713
Duncan Sandsd63e1c82010-10-04 10:06:56 +0000714<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
715actively maintained. If you are interested in Ada, we recommend that you
716consider using <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattnere38ac152008-02-12 06:29:45 +0000717</div>
718
Chris Lattner3d482502003-10-02 04:57:28 +0000719<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000720<div class="doc_section">
721 <a name="additionalinfo">Additional Information</a>
722</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000723<!-- *********************************************************************** -->
724
Misha Brukman80731b92003-11-22 00:38:41 +0000725<div class="doc_text">
726
Chris Lattnercb5596d2005-05-16 17:13:10 +0000727<p>A wide variety of additional information is available on the <a
Chris Lattnere0c1df42007-05-18 00:44:29 +0000728href="http://llvm.org">LLVM web page</a>, in particular in the <a
729href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencerc7f87f22007-07-09 08:04:31 +0000730contains versions of the API documentation which is up-to-date with the
731Subversion version of the source code.
Misha Brukman96158092005-03-30 19:14:24 +0000732You can access versions of these documents specific to this release by going
733into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000734
Misha Brukman80731b92003-11-22 00:38:41 +0000735<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnera69595e2005-10-29 07:07:09 +0000736us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattnerb84f3322003-12-12 21:22:16 +0000737lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000738
Misha Brukman80731b92003-11-22 00:38:41 +0000739</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000740
741<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000742
Misha Brukman80731b92003-11-22 00:38:41 +0000743<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000744<address>
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Misha Brukman68aab3b2003-11-22 01:23:39 +0000749
Chris Lattnere0c1df42007-05-18 00:44:29 +0000750 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000751 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000752</address>
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