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Dan Gohmanb44f6c62010-05-03 23:51:05 +00008 <title>LLVM 2.8 Release Notes</title>
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10<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +000011
Dan Gohmanb44f6c62010-05-03 23:51:05 +000012<div class="doc_title">LLVM 2.8 Release Notes</div>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000013
Chris Lattner0e464a92010-03-17 04:02:39 +000014<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greifee2187a2010-04-22 10:21:43 +000015 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattner0e464a92010-03-17 04:02:39 +000016
Chris Lattner79c3fe12003-10-02 04:57:28 +000017<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000018 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +000019 <li><a href="#subproj">Sub-project Status Update</a></li>
Dan Gohmanb44f6c62010-05-03 23:51:05 +000020 <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 +000022 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Dan Gohman44aa9212008-10-14 16:23:02 +000023 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +000024 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000025</ol>
26
Chris Lattner7911ce22004-05-23 21:07:27 +000027<div class="doc_author">
Dan Gohman44aa9212008-10-14 16:23:02 +000028 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman500bc302003-11-22 00:38:41 +000029</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000030
Chris Lattnere07043c2010-09-29 05:30:03 +000031<!--
Chris Lattner7b91eda2010-04-22 05:41:35 +000032<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.8
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000033release.<br>
34You may prefer the
Dan Gohmanb44f6c62010-05-03 23:51:05 +000035<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 +000037-->
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000038
Chris Lattner79c3fe12003-10-02 04:57:28 +000039<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000040<div class="doc_section">
41 <a name="intro">Introduction</a>
42</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000043<!-- *********************************************************************** -->
44
Misha Brukman500bc302003-11-22 00:38:41 +000045<div class="doc_text">
46
Chris Lattnerf6662f92008-10-13 17:57:36 +000047<p>This document contains the release notes for the LLVM Compiler
Dan Gohman7ae3ac82010-05-03 23:52:21 +000048Infrastructure, release 2.8. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +000049major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +000050All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +000051href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +000052
Chris Lattner7506b1d2004-12-07 08:04:13 +000053<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000054release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000055web site</a>. If you have questions or comments, the <a
Chris Lattnerc66bfef2010-03-17 04:41:49 +000056href="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 +000058
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000059<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +000060main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +000061current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +000062<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +000063
64</div>
Chris Lattner61358ab2009-10-13 17:48:04 +000065
Chris Lattner79c3fe12003-10-02 04:57:28 +000066
Chris Lattner61358ab2009-10-13 17:48:04 +000067<!--
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 +000071 GEPSplitterPass
Chris Lattner61358ab2009-10-13 17:48:04 +000072-->
73
74
Chris Lattnere07043c2010-09-29 05:30:03 +000075<!-- Features that need text if they're finished for 2.9:
Chris Lattner914ce462010-04-22 06:28:20 +000076 combiner-aa?
Chris Lattner61358ab2009-10-13 17:48:04 +000077 strong phi elim
Chris Lattner61358ab2009-10-13 17:48:04 +000078 loop dependence analysis
Chris Lattner885b6612010-08-28 16:33:36 +000079 TBAA
Chris Lattnere07043c2010-09-29 05:30:03 +000080 CorrelatedValuePropagation
Chris Lattneracce85d2008-02-10 07:46:44 +000081 -->
Chris Lattnere07043c2010-09-29 05:30:03 +000082
83 <!-- Announcement, lldb, libc++ -->
Chris Lattnerafa41632010-09-29 07:25:03 +000084
Chris Lattneracce85d2008-02-10 07:46:44 +000085
Chris Lattner96a445e2008-10-13 18:01:01 +000086<!-- *********************************************************************** -->
87<div class="doc_section">
88 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +000089</div>
Chris Lattner96a445e2008-10-13 18:01:01 +000090<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +000091
92<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +000093<p>
Dan Gohmanb44f6c62010-05-03 23:51:05 +000094The LLVM 2.8 distribution currently consists of code from the core LLVM
Chris Lattner61358ab2009-10-13 17:48:04 +000095repository (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 +000099</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000100
Chris Lattner8348b472008-06-08 21:58:17 +0000101</div>
102
Chris Lattner96a445e2008-10-13 18:01:01 +0000103
Chris Lattner8348b472008-06-08 21:58:17 +0000104<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +0000105<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000106<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000107</div>
108
109<div class="doc_text">
110
Chris Lattner095539f2010-04-26 17:42:18 +0000111<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 +0000117production-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 +0000119
Chris Lattner922d00f2010-07-21 15:57:40 +0000120<p>In the LLVM 2.8 time-frame, the Clang team has made many improvements:</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000121
Daniel Dunbar13739432008-10-14 23:25:09 +0000122<ul>
Chris Lattnere07043c2010-09-29 05:30:03 +0000123<li>Surely these guys have done something</li>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000124<li>X86-64 abi improvements? Did they make it in?</li>
Bill Wendling6bc15282009-03-02 04:28:18 +0000125</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000126</div>
127
128<!--=========================================================================-->
129<div class="doc_subsection">
130<a name="clangsa">Clang Static Analyzer</a>
131</div>
132
133<div class="doc_text">
134
Chris Lattner8cdd7932010-04-22 06:38:11 +0000135<p>The <a href="http://clang-analyzer.llvm.org/">Clang Static Analyzer</a>
136 project is an effort to use static source code analysis techniques to
137 automatically find bugs in C and Objective-C programs (and hopefully <a
138 href="http://clang-analyzer.llvm.org/dev_cxx.html">C++ in the
139 future</a>!). The tool is very good at finding bugs that occur on specific
140 paths through code, such as on error conditions.</p>
Chris Lattnercc042612008-10-14 00:52:49 +0000141
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000142<p>The LLVM 2.8 release fixes a number of bugs and slightly improves precision
143 over 2.7, but there are no major new features in the release.
Chris Lattner8cdd7932010-04-22 06:38:11 +0000144</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000145
146</div>
147
Chris Lattner96a445e2008-10-13 18:01:01 +0000148<!--=========================================================================-->
149<div class="doc_subsection">
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000150<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000151</div>
152
153<div class="doc_text">
154<p>
Nicolas Geoffray99a4d302008-10-14 19:23:04 +0000155The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000156a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
157just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage
158collectors, and can be configured to use MMTk's copy mark-sweep garbage
159collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained.
160</p>
Chris Lattner96a445e2008-10-13 18:01:01 +0000161</div>
162
Chris Lattner61358ab2009-10-13 17:48:04 +0000163
164<!--=========================================================================-->
165<div class="doc_subsection">
166<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
167</div>
168
169<div class="doc_text">
170<p>
171The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
172is a simple library that provides an implementation of the low-level
173target-specific hooks required by code generation and other runtime components.
174For example, when compiling for a 32-bit target, converting a double to a 64-bit
175unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
176function. The compiler-rt library provides highly optimized implementations of
177this and other low-level routines (some are 3x faster than the equivalent
178libgcc routines).</p>
179
180<p>
181All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000182License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports
183soft floating point (for targets that don't have a real floating point unit),
184and includes an extensive testsuite for the "blocks" language feature and the
185blocks runtime included in compiler_rt.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000186
187</div>
188
189<!--=========================================================================-->
190<div class="doc_subsection">
Duncan Sands749fd832010-04-02 09:23:15 +0000191<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattner61358ab2009-10-13 17:48:04 +0000192</div>
193
194<div class="doc_text">
195<p>
Duncan Sands749fd832010-04-02 09:23:15 +0000196<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000197gcc-4.5. Unlike llvm-gcc, dragonegg in theory does not require any gcc-4.5
198modifications whatsoever (currently one small patch is needed) thanks to the
199new <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>.
200DragonEgg is a gcc plugin that makes gcc-4.5 use the LLVM optimizers and code
201generators instead of gcc's, just like with llvm-gcc.
Duncan Sands749fd832010-04-02 09:23:15 +0000202</p>
203
204<p>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000205DragonEgg is still a work in progress, but it is able to compile a lot of code,
206for example all of gcc, LLVM and clang. Currently Ada, C, C++ and Fortran work
207well, while all other languages either don't work at all or only work poorly.
208For the moment only the x86-32 and x86-64 targets are supported, and only on
209linux and darwin (darwin may need additional gcc patches).
Duncan Sands749fd832010-04-02 09:23:15 +0000210</p>
211
212<p>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000213The 2.8 release has the following notable changes:
214<ul>
215<li>The plugin loads faster due to exporting fewer symbols.</li>
216<li>Additional vector operations such as addps256 are now supported.</li>
217<li>Ada global variables with no initial value are no longer zero initialized,
218resulting in better optimization.</li>
219<li>The '-fplugin-arg-dragonegg-enable-gcc-optzns' flag now runs all gcc
220optimizers, rather than just a handful.</li>
221<li>Fortran programs using common variables now link correctly.</li>
222<li>GNU OMP constructs no longer crash the compiler.</li>
223</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000224</p>
225
226</div>
227
228
229<!--=========================================================================-->
230<div class="doc_subsection">
Chris Lattnere07043c2010-09-29 05:30:03 +0000231<a name="lldb">LLDB: Low Level Debugger</a>
232</div>
233
234<div class="doc_text">
235<p>
236<a href="http://lldb.llvm.org/">LLDB</a> is</p>
237
238<p>
239</p>
240
241<p>
2422.8 status here.
243</p>
244
245</div>
246
247<!--=========================================================================-->
248<div class="doc_subsection">
249<a name="libc++">libc++: C++ Standard Library</a>
250</div>
251
252<div class="doc_text">
253<p>
254<a href="http://libc++.llvm.org/">libc++</a> is</p>
255
256<p>
257</p>
258
259<p>
2602.8 status here.
261</p>
262
263</div>
264
Chris Lattner61358ab2009-10-13 17:48:04 +0000265
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000266<!-- *********************************************************************** -->
267<div class="doc_section">
Chris Lattner922d00f2010-07-21 15:57:40 +0000268 <a name="externalproj">External Open Source Projects Using LLVM 2.8</a>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000269</div>
270<!-- *********************************************************************** -->
271
Chris Lattner61358ab2009-10-13 17:48:04 +0000272<div class="doc_text">
273
274<p>An exciting aspect of LLVM is that it is used as an enabling technology for
275 a lot of other language and tools projects. This section lists some of the
Chris Lattner922d00f2010-07-21 15:57:40 +0000276 projects that have already been updated to work with LLVM 2.8.</p>
Chris Lattner7c8e7962010-04-26 17:38:10 +0000277</div>
278
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000279<!--=========================================================================-->
280<div class="doc_subsection">
281<a name="tce">TTA-based Codesign Environment (TCE)</a>
282</div>
283
284<div class="doc_text">
285<p>
286<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
287application-specific processors (ASP) based on the Transport triggered
288architecture (TTA). The toolset provides a complete co-design flow from C/C++
289programs down to synthesizable VHDL and parallel program binaries. Processor
290customization points include the register files, function units, supported
291operations, and the interconnection network.</p>
292
293<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
294independent optimizations and also for parts of code generation. It generates
295new LLVM-based code generators "on the fly" for the designed TTA processors and
296loads them in to the compiler backend as runtime libraries to avoid per-target
297recompilation of larger parts of the compiler chain.</p>
298
299</div>
300
301<!--=========================================================================-->
302<div class="doc_subsection">
303<a name="Horizon">Horizon Bytecode Compiler</a>
304</div>
305
306<div class="doc_text">
307<p>
308<a href="http://www.quokforge.org/projects/horizon">Horizon</a> is a bytecode
309language and compiler written on top of LLVM, intended for producing
310single-address-space managed code operating systems that
311run faster than the equivalent multiple-address-space C systems.
312More in-depth blurb is available on <a
313href="http://www.quokforge.org/projects/horizon/wiki/Wiki">the wiki</a>.</p>
314
315</div>
316
317<!--=========================================================================-->
318<div class="doc_subsection">
319<a name="clamav">Clam AntiVirus</a>
320</div>
321
322<div class="doc_text">
323<p>
324<a href=http://www.clamav.net>Clam AntiVirus</a> is an open source (GPL)
325anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail
326gateways. Since version 0.96 it has <a
327href="http://vrt-sourcefire.blogspot.com/2010/09/introduction-to-clamavs-low-level.html">bytecode
328signatures</a> that allow writing detections for complex malware. It
329uses LLVM's JIT to speed up the execution of bytecode on
330X86,X86-64,PPC32/64, falling back to its own interpreter otherwise.
331The git version was updated to work with LLVM 2.8
332</p>
333
334<p>The <a
335href="http://git.clamav.net/gitweb?p=clamav-bytecode-compiler.git;a=blob_plain;f=docs/user/clambc-user.pdf">
336ClamAV bytecode compiler</a> uses Clang and LLVM to compile a C-like
337language, insert runtime checks, and generate ClamAV bytecode.</p>
338
339</div>
340
341<!--=========================================================================-->
342<div class="doc_subsection">
343<a name="pure">Pure</a>
344</div>
345
346<div class="doc_text">
347<p>
348<a href="http://pure-lang.googlecode.com/">Pure</a>
349is an algebraic/functional
350programming language based on term rewriting. Programs are collections
351of equations which are used to evaluate expressions in a symbolic
352fashion. Pure offers dynamic typing, eager and lazy evaluation, lexical
353closures, a hygienic macro system (also based on term rewriting),
354built-in list and matrix support (including list and matrix
355comprehensions) and an easy-to-use C interface. The interpreter uses
356LLVM as a backend to JIT-compile Pure programs to fast native code.</p>
357
358<p>Pure versions 0.44 and later have been tested and are known to work with
359LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).</p>
360
361</div>
362
363<!--=========================================================================-->
364<div class="doc_subsection">
365<a name="GHC">Glasgow Haskell Compiler (GHC)</a>
366</div>
367
368<div class="doc_text">
369<p>
370<a href="http://www.haskell.org/ghc/">GHC</a> is an open source,
371state-of-the-art programming suite for
372Haskell, a standard lazy functional programming language. It includes
373an optimizing static compiler generating good code for a variety of
374platforms, together with an interactive system for convenient, quick
375development.</p>
376
377<p>In addition to the existing C and native code generators, GHC 7.0 now
378supports an <a
379href="http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/Backends/LLVM">LLVM
380code generator</a>. GHC supports LLVM 2.7 and later.</p>
381
382</div>
383
384<!--=========================================================================-->
385<div class="doc_subsection">
386<a name="Clay">Clay Programming Language</a>
387</div>
388
389<div class="doc_text">
390<p>
Chris Lattner97fe6452010-09-30 01:12:09 +0000391<a href="http://tachyon.in/clay/">Clay</a> is a new systems programming
Chris Lattner2e38c7f2010-09-30 00:34:43 +0000392language that is specifically designed for generic programming. It makes
393generic programming very concise thanks to whole program type propagation. It
394uses LLVM as its backend.</p>
395
396</div>
Chris Lattner3a1d4cf2010-04-22 21:34:16 +0000397
Chris Lattnere0518442010-10-01 06:34:49 +0000398<!--=========================================================================-->
399<div class="doc_subsection">
400<a name="llvm-py">llvm-py Python Bindings for LLVM</a>
401</div>
402
403<div class="doc_text">
404<p>
405<a href="http://www.mdevan.org/llvm-py/">llvm-py</a> has been updated to work
406with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a
407compiler backend or a VM in Python.</p>
408
409</div>
410
411
Chris Lattner2fb6e5c2010-10-03 23:09:03 +0000412<!--=========================================================================-->
413<div class="doc_subsection">
414<a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a>
415</div>
416
417<div class="doc_text">
418<p>
419<a href="http://faust.grame.fr">FAUST</a> is a compiled language for real-time
420audio signal processing. The name FAUST stands for Functional AUdio STream. Its
421programming model combines two approaches: functional programming and block
422diagram composition. In addition with the C, C++, JAVA output formats, the
423Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and
4242.8.</p>
425
426</div>
427
428<!--=========================================================================-->
429<div class="doc_subsection">
430<a name="jade">Jade Just-in-time Adaptive Decoder Engine</a>
431</div>
432
433<div class="doc_text">
434<p><a
435href="http://sourceforge.net/apps/trac/orcc/wiki/JadeDocumentation">Jade</a>
436(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using
437LLVM for just-in-time compilation of video decoder configurations. Those
438configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee.
439MPEG RVC standard is built on a stream-based dataflow representation of
440decoders. It is composed of a standard library of coding tools written in
441RVC-CAL language and a dataflow configuration &emdash; block diagram &emdash;
442of a decoder.</p>
443
444<p>Jade project is hosted as part of the <a href="http://orcc.sf.net">Open
445RVC-CAL Compiler</a> and requires it to translate the RVC-CAL standard library
446of video coding tools into an LLVM assembly code.</p>
447
448</div>
449
450<!--=========================================================================-->
451<div class="doc_subsection">
452<a name="neko_llvm_jit">LLVM JIT for Neko VM</a>
453</div>
454
455<div class="doc_text">
456<p><a href="http://github.com/vava/neko_llvm_jit">Neko LLVM JIT</a>
457replaces the standard Neko JIT with an LLVM-based implementation. While not
458fully complete, it is already providing a 1.5x speedup on 64-bit systems.
459Neko LLVM JIT requires LLVM 2.8 or later.</p>
460
461</div>
462
463<!--=========================================================================-->
464<div class="doc_subsection">
465<a name="crack">Crack Scripting Language</a>
466</div>
467
468<div class="doc_text">
469<p>
470<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide
471the ease of development of a scripting language with the performance of a
472compiled language. The language derives concepts from C++, Java and Python,
473incorporating object-oriented programming, operator overloading and strong
474typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release
475builds on LLVM 2.8.</p>
476
477</div>
478
479<!--=========================================================================-->
480<div class="doc_subsection">
481<a name="DresdenTM">Dresden TM Compiler (DTMC)</a>
482</div>
483
484<div class="doc_text">
485<p>
486<a href="http://tm.inf.tu-dresden.de">DTMC</a> provides support for
487Transactional Memory, which is an easy-to-use and efficient way to synchronize
488accesses to shared memory. Transactions can contain normal C/C++ code (e.g.,
489__transaction { list.remove(x); x.refCount--; }) and will be executed
490virtually atomically and isolated from other transactions.</p>
491
492</div>
493
494<!--=========================================================================-->
495<div class="doc_subsection">
496<a name="Kai">Kai Interpreter</a>
497</div>
498
499<div class="doc_text">
500<p>
501<a href="http://www.oriontransfer.co.nz/research/kai">Kai</a> (Japanese 会 for
502meeting/gathering) is an experimental interpreter that provides a highly
503extensible runtime environment and explicit control over the compilation
504process. Programs are defined using nested symbolic expressions, which are all
505parsed into first-class values with minimal intrinsic semantics. Kai can
506generate optimised code at run-time (using LLVM) in order to exploit the nature
507of the underlying hardware and to integrate with external software libraries.
508It is a unique exploration into world of dynamic code compilation, and the
509interaction between high level and low level semantics.</p>
510
511</div>
512
Chris Lattnere0518442010-10-01 06:34:49 +0000513
Chris Lattner8348b472008-06-08 21:58:17 +0000514<!-- *********************************************************************** -->
515<div class="doc_section">
Chris Lattner922d00f2010-07-21 15:57:40 +0000516 <a name="whatsnew">What's New in LLVM 2.8?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000517</div>
518<!-- *********************************************************************** -->
519
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000520<div class="doc_text">
521
Chris Lattner61358ab2009-10-13 17:48:04 +0000522<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000523minor improvements. Some of the major improvements and new features are listed
524in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000525</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000526
Chris Lattner914ce462010-04-22 06:28:20 +0000527</div>
528
529<!--=========================================================================-->
530<div class="doc_subsection">
531<a name="orgchanges">LLVM Community Changes</a>
532</div>
533
534<div class="doc_text">
535
Chris Lattner922d00f2010-07-21 15:57:40 +0000536<p>In addition to changes to the code, between LLVM 2.7 and 2.8, a number of
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000537organization changes have happened:
538</p>
539
540<ul>
Chris Lattnere07043c2010-09-29 05:30:03 +0000541<li>libc++ and lldb are new</li>
Chris Lattnerafa41632010-09-29 07:25:03 +0000542<li>Debugging optimized code support.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000543</ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000544</div>
545
Chris Lattner8348b472008-06-08 21:58:17 +0000546<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000547<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000548<a name="majorfeatures">Major New Features</a>
549</div>
550
551<div class="doc_text">
552
Chris Lattner922d00f2010-07-21 15:57:40 +0000553<p>LLVM 2.8 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000554
555<ul>
Chris Lattner702f2d42010-09-06 19:14:40 +0000556<li>llvm-diff</li>
Chris Lattner4eac9242010-10-02 22:44:15 +0000557<li>Direct .o file writing support for darwin/x86[64].</li>
Chris Lattner8170c102008-02-10 08:18:42 +0000558</ul>
Chris Lattnerdc910082010-03-17 06:41:58 +0000559
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000560</div>
561
Chris Lattner84977642007-09-21 03:54:09 +0000562<!--=========================================================================-->
563<div class="doc_subsection">
Chris Lattner917cc712009-03-02 02:37:32 +0000564<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000565</div>
566
567<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000568<p>LLVM IR has several new features for better support of new targets and that
569expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000570
Chris Lattner791f77b2008-06-05 06:25:56 +0000571<ul>
Gabor Greif17b59fe2010-07-21 10:20:08 +0000572
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000573 memcpy, memmove, and memset now take address space qualified pointers + volatile.
574 per-instruction debug info metadata is much faster and uses less space (new DebugLoc class).
575 New "trap values" concept: http://llvm.org/docs/LangRef.html#trapvalues
576 New linker_private_weak and linker_private_weak_def_auto linkage types
577 Triples are now stored in normalized form. Triple::normalize.
578
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000579</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000580
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000581</div>
582
583<!--=========================================================================-->
584<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000585<a name="optimizer">Optimizer Improvements</a>
586</div>
587
588<div class="doc_text">
589
Chris Lattner61358ab2009-10-13 17:48:04 +0000590<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerf3013872008-10-13 21:50:36 +0000591release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000592
593<ul>
594
Chris Lattner922d00f2010-07-21 15:57:40 +0000595<li></li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000596 Preliminary work on TBAA but not usable in 2.8.
597 New CorrelatedValuePropagation pass, not on by default in 2.8 yet.
598 JumpThreading much more aggressive about implied value relations.
599 New RegionInfo pass "opt -regions analyze" or "opt -view-regions".
600 Improved trip count analysis for <= and >= loops, and uses sign overflow info.
601 llvm.dbg.value: variable debug info for optimized code
602 Now iterate function passes when a cgsccpassmanager detects a devirtualization
603 Atomic lowering patch: -loweratomic (see Passes.html#loweratomic)
Chris Lattnera54c1f72010-04-21 06:42:24 +0000604
Chris Lattner61358ab2009-10-13 17:48:04 +0000605</ul>
Chris Lattner917cc712009-03-02 02:37:32 +0000606
Chris Lattner61358ab2009-10-13 17:48:04 +0000607</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000608
Chris Lattner917cc712009-03-02 02:37:32 +0000609
Chris Lattner61358ab2009-10-13 17:48:04 +0000610<!--=========================================================================-->
611<div class="doc_subsection">
612<a name="executionengine">Interpreter and JIT Improvements</a>
613</div>
Chris Lattnerf3013872008-10-13 21:50:36 +0000614
Chris Lattner61358ab2009-10-13 17:48:04 +0000615<div class="doc_text">
616
617<ul>
Chris Lattner922d00f2010-07-21 15:57:40 +0000618<li></li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000619
Chris Lattner0b832202008-06-08 02:45:07 +0000620</ul>
621
622</div>
623
624<!--=========================================================================-->
625<div class="doc_subsection">
Chris Lattner4ba2b652010-09-30 16:31:33 +0000626<a name="mc">MC Level Improvements</a>
627</div>
628
629<div class="doc_text">
630<p>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000631The LLVM Machine Code (aka MC) subsystem was created to solve a number
Chris Lattner4ba2b652010-09-30 16:31:33 +0000632of problems in the realm of assembly, disassembly, object file format handling,
633and a number of other related areas that CPU instruction-set level tools work
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000634in.</p>
635
636<p>The MC subproject has made great leaps in LLVM 2.8. For example, support for
637 directly writing .o files from LLC (and clang) now works reliably for
638 darwin/x86[-64] (including inline assembly support) and the integrated
639 assembler is turned on by default in Clang for these targets. This provides
640 improved compile times among other things.</p>
641
642<ul>
643<li>The entire compiler has converted over to using the MCStreamer assembler API
644 instead of writing out a .s file textually.</li>
645<li>The "assembler parser" is far more mature than in 2.7, supporting a full
646 complement of directives, now supports assembler macros, etc.</li>
647<li>The "assembler backend" has been completed, including support for relaxation
648 relocation processing and all the other things that an assembler does.</li>
649<li>The MachO file format support is now fully functional and works.</li>
650<li>The MC disassembler now fully supports ARM and Thumb. ARM assembler support
651 is still in early development though.</li>
652<li>The X86 MC assembler now supports the X86 AES and AVX instruction set.</li>
653<li>Work on ELF and COFF support is well underway, but isn't useful yet in LLVM
654 2.8. Please contact the llvmdev mailing list if you're interested in
655 this.</li>
656</ul>
657
658<p>For more information, please see the <a
Chris Lattner4ba2b652010-09-30 16:31:33 +0000659href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
660LLVM MC Project Blog Post</a>.
661</p>
662
Chris Lattner4ba2b652010-09-30 16:31:33 +0000663</div>
664
665
666
667<!--=========================================================================-->
668<div class="doc_subsection">
Chris Lattner511433e2009-03-02 03:24:11 +0000669<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000670</div>
671
672<div class="doc_text">
673
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000674<p>We have put a significant amount of work into the code generator
675infrastructure, which allows us to implement more aggressive algorithms and make
676it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000677
678<ul>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000679<li></li>
680
681 MachineCSE tuned and on by default.
682
683 Rewrote tblgen's type inference for backends to be more consistent and
684 diagnose more target bugs. This also allows limited support for writing
685 patterns for instructions that return multiple results, e.g. a virtual
686 register and a flag result. Stuff that used 'parallel' before should use
687 this.
688
689 New -regalloc=fast, =local got removed
690 New -regalloc=default option that chooses a register allocator based on the -O optimization level.
691 New SubRegIndex tblgen class for targets -> jakob
692
693 Bottom up fast isel. Simple Load reuse. No more machinedce.
694 IR ABI: <3 x float> is passed as <4 x float> instead of 3 floats.
695
696 New COPY instruction. copyRegToReg -> copyPhysReg, isMoveInstr is gone.
697 RenderMachineFunction: -rendermf
698 SplitKit?
699 Evan: Teach bottom up pre-ra scheduler to track register pressure. Work in progress.
700 Evan: Add an ILP scheduler. On x86_64, this is a win for all tests in CFP2000. It also sped up 256.bzip2 by 16%.
701
702 New OptimizeExts+OptimizeCmps -> PeepholeOptimizer pass
703 New LocalStackSlotAllocation.cpp pass (jimg)
704 Atomics now get legalized when not natively supported (jim g)
705
706 -ffunction-sections and -fdata-sections are supported on ELF targets.
707 -momit-leaf-frame-pointer now supported.
708
Chris Lattner84977642007-09-21 03:54:09 +0000709</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000710</div>
711
Chris Lattner917cc712009-03-02 02:37:32 +0000712<!--=========================================================================-->
713<div class="doc_subsection">
714<a name="x86">X86-32 and X86-64 Target Improvements</a>
715</div>
716
717<div class="doc_text">
718<p>New features of the X86 target include:
719</p>
720
721<ul>
Chris Lattner922d00f2010-07-21 15:57:40 +0000722<li>The X86 backend now supports holding X87 floating point stack values
723 in registers across basic blocks, dramatically improving performance of code
724 that uses long double, and when targetting CPUs that don't support SSE.</li>
Chris Lattner511433e2009-03-02 03:24:11 +0000725
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000726 New SSEDomainFix pass:
727 On Nehalem and newer CPUs there is a 2 cycle latency penalty on using a
728 register in a different domain than where it was defined. Some instructions
729 have equvivalents for different domains, like por/orps/orpd. The
730 SSEDomainFix pass tries to minimize the number of domain crossings by
731 changing between equvivalent opcodes where possible.
732
733 X86 backend attempts to promote 16-bit integer operations to 32-bits to avoid
734 0x66 prefixes, which are slow on some microarchitectures and bloat the code
735 on others.
736
737 New support for X86 "thiscall" calling convention (x86_thiscallcc in IR) for windows.
738
739 New llvm.x86.int intrinsic (for int $42 and int3)
740
741 Verbose assembly decodes X86 shuffle instructions, e.g.:
742 insertps $113, %xmm3, %xmm0 ## xmm0 = zero,xmm0[1,2],xmm3[1]
743 unpcklps %xmm1, %xmm0 ## xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]
744 pshufd $1, %xmm1, %xmm1 ## xmm1 = xmm1[1,0,0,0]
745
746 X86 ABI: <2 x float> in IR no longer maps onto MMX, it turns into <4 x float>
747
748 new GHC calling convention
749
Chris Lattner917cc712009-03-02 02:37:32 +0000750</ul>
751
Chris Lattner917cc712009-03-02 02:37:32 +0000752</div>
Chris Lattner84977642007-09-21 03:54:09 +0000753
754<!--=========================================================================-->
755<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000756<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000757</div>
758
759<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000760<p>New features of the ARM target include:
761</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000762
763<ul>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000764
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000765 NEON: Better performance for QQQQ (4-consecutive Q register) instructions. New reg sequence abstraction?
766 ARM: Better scheduling (list-hybrid, hybrid?)
767 ARM: Tail call support.
768 ARM: General performance work and tuning.
769
770 ARM: Half float support through intrinsics LangRef.html#int_fp16
771<li>ARMGlobalMerge: <!-- Anton --> </li>
772
Chris Lattner4eac9242010-10-02 22:44:15 +0000773<li>The ARM NEON intrinsics have been substantially reworked to reduce
774 redundancy and improve code generation. Some of the major changes are:
775 <ol>
776 <li>
777 All of the NEON load and store intrinsics (llvm.arm.neon.vld* and
778 llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes
779 of the memory being accessed.
780 </li>
781 <li>
782 The llvm.arm.neon.vaba intrinsic (vector absolute difference and
783 accumulate) has been removed. This operation is now represented using
784 the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a
785 vector add.
786 </li>
787 <li>
788 The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening
789 vector absolute difference with and without accumlation) have been removed.
790 They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute
791 difference) followed by a vector zero-extend operation, and for vabal,
792 a vector add.
793 </li>
794 <li>
795 The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic
796 are now replaced by vector truncate operations.
797 </li>
798 <li>
799 The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been
800 removed. They are now represented as vector sign-extend (vmovls) and
801 zero-extend (vmovlu) operations.
802 </li>
803 <li>
804 The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and
805 llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have
806 been removed. They are replaced by vector add and vector subtract operations
807 where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either
808 sign-extended or zero-extended.
809 </li>
810 <li>
811 The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and
812 llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without
813 accumulation and subtraction) have been removed. These operations are now
814 represented as vector multiplications where the operands are either
815 sign-extended or zero-extended, followed by a vector add for vmlal or a
816 vector subtract for vmlsl. Note that the polynomial vector multiply
817 intrinsic, llvm.arm.neon.vmullp, remains unchanged.
818 </li>
819 </ol>
Bob Wilson5b2fb952010-09-13 17:37:55 +0000820</li>
Bob Wilsone8472772010-09-13 17:39:35 +0000821</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000822</div>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000823
Chris Lattner61358ab2009-10-13 17:48:04 +0000824<!--=========================================================================-->
825<div class="doc_subsection">
Chris Lattner61358ab2009-10-13 17:48:04 +0000826<a name="newapis">New Useful APIs</a>
827</div>
828
829<div class="doc_text">
830
831<p>This release includes a number of new APIs that are used internally, which
832 may also be useful for external clients.
833</p>
834
835<ul>
Chris Lattner922d00f2010-07-21 15:57:40 +0000836<li></li>
Chris Lattner61358ab2009-10-13 17:48:04 +0000837</ul>
838
839
840</div>
841
842<!--=========================================================================-->
843<div class="doc_subsection">
844<a name="otherimprovements">Other Improvements and New Features</a>
845</div>
846
847<div class="doc_text">
848<p>Other miscellaneous features include:</p>
849
850<ul>
Chris Lattner922d00f2010-07-21 15:57:40 +0000851<li></li>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000852</ul>
853
854</div>
855
Chris Lattner77d29b12008-06-05 08:02:49 +0000856
857<!--=========================================================================-->
858<div class="doc_subsection">
Chris Lattnerf6662f92008-10-13 17:57:36 +0000859<a name="changes">Major Changes and Removed Features</a>
860</div>
861
862<div class="doc_text">
863
Chris Lattnereeb4da02008-10-13 22:06:31 +0000864<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattner922d00f2010-07-21 15:57:40 +0000865on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000866from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000867
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000868
869 renamed "Release" -> "Release+Asserts"; "Release-Asserts" -> "Release etc.
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000870
871
Chris Lattnerf6662f92008-10-13 17:57:36 +0000872<ul>
Chris Lattner2295b5a2010-09-02 23:22:50 +0000873<li>.ll file doesn't produce #uses comments anymore, to get them, run a .bc file
874 through "llvm-dis --show-annotations".</li>
Chris Lattner885b6612010-08-28 16:33:36 +0000875<li>MSIL Backend removed.</li>
876<li>ABCD and SSI passes removed.</li>
877<li>'Union' LLVM IR feature removed.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000878<li>SCCVN pass removed.</li>
Chris Lattnerb7c85b42010-04-21 05:17:40 +0000879</ul>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000880
881<p>In addition, many APIs have changed in this release. Some of the major LLVM
882API changes are:</p>
Chris Lattnereeb4da02008-10-13 22:06:31 +0000883<ul>
Chris Lattner4eac9242010-10-02 22:44:15 +0000884
885 RegisterPass<> -> INTIALIZE_PASS()
886
887
888
889<li>LLVM 2.8 changes the internal order of operands in <a
890 href="http://llvm.org/doxygen/classllvm_1_1InvokeInst.html"><tt>InvokeInst</tt></a>
891 and <a href="http://llvm.org/doxygen/classllvm_1_1CallInst.html"><tt>CallInst</tt></a>.
892 To be portable across releases, resort to <tt>CallSite</tt> and the
893 high-level accessors, such as <tt>getCalledValue</tt> and <tt>setUnwindDest</tt>.
894</li>
895<li>
896 You can no longer pass use_iterators directly to cast<> (and similar), because
897 these routines tend to perform costly dereference operations more than once. You
898 have to dereference the iterators yourself and pass them in.
899</li>
900<li>
901 llvm.memcpy.*, llvm.memset.*, llvm.memmove.* (and possibly other?) intrinsics
902 take an extra parameter now (i1 isVolatile), totaling 5 parameters.
903 If you were creating these intrinsic calls and prototypes yourself (as opposed
904 to using Intrinsic::getDeclaration), you can use UpgradeIntrinsicFunction/UpgradeIntrinsicCall
905 to be portable accross releases.
906 Note that you cannot use Intrinsic::getDeclaration() in a backwards compatible
907 way (needs 2/3 types now, in 2.7 it needed just 1).
908</li>
909<li>
910 SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode.
911 Change your code to use
912 SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)).
913</li>
914<li>
915 VISIBILITY_HIDDEN is gone.
916</li>
917<li>
918 The <tt>RegisterPass</tt> and <tt>RegisterAnalysisGroup</tt> templates are
919 considered deprecated, but continue to function in LLVM 2.8. Clients are
920 strongly advised to use the upcoming <tt>INITIALIZE_PASS()</tt> and
921 <tt>INITIALIZE_AG_PASS()</tt> macros instead.
922<li>
923 SMDiagnostic takes different parameters now. //FIXME: how to upgrade?
924</li>
925<li>
926 The constructor for the Triple class no longer tries to understand odd triple
927 specifications. Frontends should ensure that they only pass valid triples to
928 LLVM. The Triple::normalize utility method has been added to help front-ends
929 deal with funky triples.
930<li>
931 Some APIs got renamed:
932 <ul>
933 <li>llvm_report_error -&gt; report_fatal_error</li>
934 <li>llvm_install_error_handler -&gt; install_fatal_error_handler</li>
935 <li>llvm::DwarfExceptionHandling -&gt; llvm::JITExceptionHandling</li>
936 </ul>
937</li>
938
Devang Patelb34dd132008-10-14 20:03:43 +0000939</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000940
Chris Lattnerf6662f92008-10-13 17:57:36 +0000941</div>
942
943
Chris Lattner79c3fe12003-10-02 04:57:28 +0000944<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000945<div class="doc_section">
946 <a name="knownproblems">Known Problems</a>
947</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000948<!-- *********************************************************************** -->
949
Misha Brukman500bc302003-11-22 00:38:41 +0000950<div class="doc_text">
951
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000952<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000953listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000954href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000955there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000956
Misha Brukman500bc302003-11-22 00:38:41 +0000957</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000958
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000959<!-- ======================================================================= -->
960<div class="doc_subsection">
961 <a name="experimental">Experimental features included with this release</a>
962</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000963
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000964<div class="doc_text">
965
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000966<p>The following components of this LLVM release are either untested, known to
967be broken or unreliable, or are in early development. These components should
968not be relied on, and bugs should not be filed against them, but they may be
969useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000970components, please contact us on the <a
971href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000972
973<ul>
Chris Lattner885b6612010-08-28 16:33:36 +0000974<li>The Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
Wesley Peck7c4a1212010-03-18 14:31:30 +0000975 backends are experimental.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000976<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
977 other than darwin-i386 and darwin-x86_64.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000978</ul>
979
980</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000981
Misha Brukman500bc302003-11-22 00:38:41 +0000982<!-- ======================================================================= -->
983<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000984 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000985</div>
986
987<div class="doc_text">
988
989<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000990 <li>The X86 backend does not yet support
991 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
992 floating point stack</a>. It supports the 'f' and 't' constraints, but not
993 'u'.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000994 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswell524a5dd2009-03-02 15:28:15 +0000995 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
Chris Lattner914ce462010-04-22 06:28:20 +0000996 runtime currently due to lack of support for the 'u' inline assembly
997 constraint and for X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000998 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000999 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +00001000 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +00001001</ul>
1002
1003</div>
1004
1005<!-- ======================================================================= -->
1006<div class="doc_subsection">
1007 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1008</div>
1009
1010<div class="doc_text">
1011
1012<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +00001013<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +00001014compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +00001015</ul>
1016
1017</div>
1018
1019<!-- ======================================================================= -->
1020<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +00001021 <a name="arm-be">Known problems with the ARM back-end</a>
1022</div>
1023
1024<div class="doc_text">
1025
1026<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +00001027<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +00001028processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +00001029results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +00001030<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +00001031</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +00001032</ul>
1033
1034</div>
1035
1036<!-- ======================================================================= -->
1037<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +00001038 <a name="sparc-be">Known problems with the SPARC back-end</a>
1039</div>
1040
1041<div class="doc_text">
1042
1043<ul>
John Criswell524a5dd2009-03-02 15:28:15 +00001044<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattner26299222006-11-18 07:51:14 +00001045 support the 64-bit SPARC ABI (-m64).</li>
1046</ul>
1047
1048</div>
1049
1050<!-- ======================================================================= -->
1051<div class="doc_subsection">
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +00001052 <a name="mips-be">Known problems with the MIPS back-end</a>
1053</div>
1054
1055<div class="doc_text">
1056
1057<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +00001058<li>64-bit MIPS targets are not supported yet.</li>
1059</ul>
1060
1061</div>
1062
1063<!-- ======================================================================= -->
1064<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +00001065 <a name="alpha-be">Known problems with the Alpha back-end</a>
1066</div>
1067
1068<div class="doc_text">
1069
1070<ul>
1071
1072<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1073appropriate nops inserted to ensure restartability.</li>
1074
John Criswellc0c186d2005-11-08 21:11:33 +00001075</ul>
1076</div>
1077
Chris Lattner26299222006-11-18 07:51:14 +00001078<!-- ======================================================================= -->
1079<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +00001080 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +00001081</div>
1082
1083<div class="doc_text">
1084
Chris Lattner3016ee92010-09-29 05:34:42 +00001085<p>The C backend has numerous problems and is not being actively maintained.
1086Depending on it for anything serious is not advised.</p>
1087
Chris Lattner26299222006-11-18 07:51:14 +00001088<ul>
Chris Lattner5733b272008-06-05 06:35:40 +00001089<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1090 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +00001091<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1092 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +00001093 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +00001094<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +00001095<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +00001096</ul>
1097
1098</div>
John Criswellc0c186d2005-11-08 21:11:33 +00001099
Misha Brukman500bc302003-11-22 00:38:41 +00001100
1101<!-- ======================================================================= -->
1102<div class="doc_subsection">
Chris Lattner3016ee92010-09-29 05:34:42 +00001103 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +00001104</div>
Chris Lattner47588f92003-10-02 05:07:23 +00001105
Misha Brukman500bc302003-11-22 00:38:41 +00001106<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +00001107
Chris Lattner3016ee92010-09-29 05:34:42 +00001108<p>llvm-gcc is generally very stable for the C family of languages. The only
1109 major language feature of GCC not supported by llvm-gcc is the
1110 <tt>__builtin_apply</tt> family of builtins. However, some extensions
1111 are only supported on some targets. For example, trampolines are only
1112 supported on some targets (these are used when you take the address of a
1113 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +00001114
Chris Lattner3016ee92010-09-29 05:34:42 +00001115<p>Fortran support generally works, but there are still several unresolved bugs
1116 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1117 tools/gfortran component for details. Note that llvm-gcc is missing major
1118 Fortran performance work in the frontend and library that went into GCC after
1119 4.2. If you are interested in Fortran, we recommend that you consider using
1120 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +00001121
Chris Lattner3016ee92010-09-29 05:34:42 +00001122<p>The llvm-gcc 4.2 Ada compiler has basic functionality. However, this is not a
1123mature technology, and problems should be expected. For example:</p>
Chris Lattner2b659ef2008-02-12 06:29:45 +00001124<ul>
Duncan Sands27aff872008-06-08 20:18:35 +00001125<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswell524a5dd2009-03-02 15:28:15 +00001126to lack of trampoline support (pointers to nested functions) on other platforms.
1127However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +00001128which does support trampolines.</li>
1129<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sands326a4982009-02-25 11:59:06 +00001130This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1131exception handling, which is used internally by the compiler.
Chris Lattner61358ab2009-10-13 17:48:04 +00001132Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +00001133<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1134and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sands326a4982009-02-25 11:59:06 +00001135(c380004 also fails with gcc-4.2 mainline).
1136If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1137causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sandsdd3e6722009-03-02 16:35:57 +00001138<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattner61358ab2009-10-13 17:48:04 +00001139<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattner2b659ef2008-02-12 06:29:45 +00001140<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattner61358ab2009-10-13 17:48:04 +00001141crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +00001142<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1143or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1144or use representation clauses that result in a field of a non-discrete type
1145starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +00001146<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1147'main' as generated by the Ada binder to be invalid</a>.
1148Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1149<tt>envp</tt> rather than integers.</li>
1150<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1151ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +00001152</ul>
1153</div>
1154
Chris Lattner79c3fe12003-10-02 04:57:28 +00001155<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +00001156<div class="doc_section">
1157 <a name="additionalinfo">Additional Information</a>
1158</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +00001159<!-- *********************************************************************** -->
1160
Misha Brukman500bc302003-11-22 00:38:41 +00001161<div class="doc_text">
1162
Chris Lattner416db102005-05-16 17:13:10 +00001163<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +00001164href="http://llvm.org">LLVM web page</a>, in particular in the <a
1165href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +00001166contains versions of the API documentation which is up-to-date with the
1167Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +00001168You can access versions of these documents specific to this release by going
1169into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +00001170
Misha Brukman500bc302003-11-22 00:38:41 +00001171<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +00001172us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +00001173lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +00001174
Misha Brukman500bc302003-11-22 00:38:41 +00001175</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +00001176
1177<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +00001178
Misha Brukman500bc302003-11-22 00:38:41 +00001179<hr>
Misha Brukman2061e892003-11-22 01:23:39 +00001180<address>
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Misha Brukman2061e892003-11-22 01:23:39 +00001185
Chris Lattnerb4b0ce72007-05-18 00:44:29 +00001186 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +00001187 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +00001188</address>
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1191</html>