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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / ce91ec285d89867f2048f93f31da198a227bba7a / . / docs / ReleaseNotes.html
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Anton Korobeynikov0d176912008-06-08 10:23:46 +0000[diff] [blame]1
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5<head>
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Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]8 <title>LLVM 2.3 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]9</head>
10<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]11
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]12<div class="doc_title">LLVM 2.3 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]13
14<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]15 <li><a href="#intro">Introduction</a></li>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]16 <li><a href="#changes">Major Changes and Sub-project Status</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]18 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]20 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]21 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]22</ol>
23
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]24<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]25 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]26</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]27
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]28<!-- Done through Week-of-Mon-20080324.txt -->
29
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]30<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]31<div class="doc_section">
32 <a name="intro">Introduction</a>
33</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]34<!-- *********************************************************************** -->
35
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]36<div class="doc_text">
37
38<p>This document contains the release notes for the LLVM compiler
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]39infrastructure, release 2.3. Here we describe the status of LLVM, including
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]40major improvements from the previous release and any known problems. All LLVM
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]41releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]42releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]43
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]44<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]45release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]46web site</a>. If you have questions or comments, the <a
47href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]48list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]49
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]50<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]51main LLVM web page, this document applies to the <i>next</i> release, not the
52current one. To see the release notes for a specific releases, please see the
53<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]54
55</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]56
57<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]58<div class="doc_section">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]59 <a name="changes">Major Changes and Sub-project Status</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]60</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]61<!-- *********************************************************************** -->
62
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]63<div class="doc_text">
64
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]65<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]66It includes a large number of features and refinements from LLVM 2.2.</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]67
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]68</div>
69
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]70<!-- Unfinished features in 2.3:
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]71 Machine LICM
72 Machine Sinking
73 LegalizeDAGTypes
74 -->
75
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]76<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]77<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]78<a name="changes">Major Changes in LLVM 2.3</a>
Chris Lattnerb4c68cd2008-02-10 07:04:35 +0000[diff] [blame]79</div>
80
81<div class="doc_text">
82
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]83<p>LLVM 2.3 no longer supports llvm-gcc 4.0, it has been replaced with
84 llvm-gcc 4.2.</p>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]85
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]86<p>LLVM 2.3 no longer includes the <tt>llvm-upgrade</tt> tool. It was useful
87 for upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a
88 previous LLVM release to do this. One nice impact of this is that the LLVM
89 regression test suite no longer depends on llvm-upgrade, which makes it run
90 faster.</p>
91
92<p>The <tt>llvm2cpp</tt> tool has been folded into llc, use
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]93 <tt>llc -march=cpp</tt> instead of <tt>llvm2cpp</tt>.</p>
94
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]95<p>LLVM API Changes:</p>
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]96
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]97<ul>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]98<li>Several core LLVM IR classes have migrated to use the
99 '<tt>FOOCLASS::Create(...)</tt>' pattern instead of '<tt>new
100 FOOCLASS(...)</tt>' (e.g. where FOOCLASS=<tt>BasicBlock</tt>). We hope to
101 standardize on <tt>FOOCLASS::Create</tt> for all IR classes in the future,
102 but not all of them have been moved over yet.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]103<li>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
Dan Gohmane3280782008-06-08 22:57:59 +0000[diff] [blame]104 <a href="http://llvm.org/doxygen/classllvm_1_1IRBuilder.html">IRBuilder</a>.
105 </li>
106<li>MRegisterInfo was renamed to
107 <a href="http://llvm.org/doxygen/classllvm_1_1TargetRegisterInfo.html">
108 TargetRegisterInfo</a>.</li>
109<li>The MappedFile class is gone, please use
110 <a href="http://llvm.org/doxygen/classllvm_1_1MemoryBuffer.html">
111 MemoryBuffer</a> instead.</li>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]112<li>The '<tt>-enable-eh</tt>' flag to llc has been removed. Now code should
113 encode whether it is safe to omit unwind information for a function by
114 tagging the Function object with the '<tt>nounwind</tt>' attribute.</li>
Dan Gohmanf821ca32008-06-09 04:36:34 +0000[diff] [blame]115<li>The ConstantFP::get method that uses APFloat now takes one argument
116 instead of two. The type argument has been removed, and the type is
117 now inferred from the size of the given APFloat value.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]118
119</ul>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]120</div>
121
122<!--=========================================================================-->
123<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]124<a name="otherprojects">Other LLVM Sub-Projects</a>
125</div>
126
127<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]128<p>
129The core LLVM 2.3 distribution currently consists of code from the core LLVM
130repository (which roughly contains the LLVM optimizer, code generators and
131supporting tools) and the llvm-gcc repository. In addition to this code, the
132LLVM Project includes other sub-projects that are in development. The two which
133are the most actively developed are the new <a href="#vmkit">vmkit Project</a>
134and the <a href="#clang">Clang Project</a>.
135</p>
136</div>
137
138<!--=========================================================================-->
139<div class="doc_subsubsection">
140<a name="vmkit">vmkit</a>
141</div>
142
143<div class="doc_text">
144<p>
145The "vmkit" project is a new addition to the LLVM family. It is an
146implementation of a JVM and a CLI Virtual Machines (Microsoft .NET is an
147implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
148
149<p>The JVM, called JnJVM, executes real-world applications such as Apache
150projects (e.g. Felix and Tomcat) and the SpecJVM98 benchmark. It uses the GNU
151Classpath project for the base classes. The CLI implementation, called N3, is
152its in early stages but can execute simple applications and the "pnetmark"
153benchmark. It uses the pnetlib project as its core library.</p>
154
155<p>The 'vmkit' VMs compare in performance with industrial and top open-source
156VMs on scientific applications. Besides the JIT, the VMs use many features of
157the LLVM framework, including the standard set of optimizations, atomic
158operations, custom function provider and memory manager for JITed methods, and
159specific virtual machine optimizations. vmkit is not an official part of LLVM
1602.3 release. It is publicly available under the LLVM license and can be
161downloaded from:
162</p>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]163
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]164<div class="doc_code">
165<pre>svn co http://llvm.org/svn/llvm-project/vmkit/trunk vmkit</pre>
166</div>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]167
168</div>
169
170<!--=========================================================================-->
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]171<div class="doc_subsubsection">
172<a name="clang">Clang</a>
173</div>
174
175<div class="doc_text">
176
177<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
178a set of new 'LLVM native' front-end technologies for the LLVM optimizer
179and code generator. Clang is continuing to make major strides forward in all
180areas. Its C and Objective-C parsing support is very solid, and the code
181generation support is far enough along to build many C applications. While not
182yet production quality, it is progressing very nicely. In addition, C++
183front-end work has started to make significant progress.</p>
184
185<p>At this point, Clang is most useful if you are interested in source-to-source
186transformations (such as refactoring) and other source-level tools for C and
187Objective-C. Clang now also includes tools for turning C code into pretty HTML,
188and includes a new <a href="http://clang.llvm.org/StaticAnalysis.html">static
Chris Lattnere7bc1362008-06-08 23:40:40 +0000[diff] [blame]189analysis tool</a> in development. This tool focuses on automatically finding
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]190bugs in C and Objective-C code.</p>
191
192</div>
193
194
195<!-- *********************************************************************** -->
196<div class="doc_section">
197 <a name="whatsnew">What's New?</a>
198</div>
199<!-- *********************************************************************** -->
200
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]201<div class="doc_text">
202
203<p>LLVM 2.3 includes a huge number of bug fixes, performance tweaks and minor
204improvements. Some of the major improvements and new features are listed in
205this section.
206</p>
207</div>
208
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]209<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]210<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]211<a name="majorfeatures">Major New Features</a>
212</div>
213
214<div class="doc_text">
215
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]216<p>LLVM 2.3 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]217
218<ul>
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]219<li><p>The biggest change in LLVM 2.3 is Multiple Return Value (MRV) support.
220 MRVs allow LLVM IR to directly represent functions that return multiple
221 values without having to pass them "by reference" in the LLVM IR. This
222 allows a front-end to generate more efficient code, as MRVs are generally
223 returned in registers if a target supports them. See the <a
224 href="LangRef.html#i_getresult">LLVM IR Reference</a> for more details.</p>
225
226 <p>MRVs are fully supported in the LLVM IR, but are not yet fully supported in
227 on all targets. However, it is generally safe to return up to 2 values from
228 a function: most targets should be able to handle at least that. MRV
229 support is a critical requirement for X86-64 ABI support, as X86-64 requires
230 the ability to return multiple registers from functions, and we use MRVs to
231 accomplish this in a direct way.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]232
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]233<li><p>LLVM 2.3 includes a complete reimplementation of the "<tt>llvmc</tt>"
234 tool. It is designed to overcome several problems with the original
235 <tt>llvmc</tt> and to provide a superset of the features of the
236 '<tt>gcc</tt>' driver.</p>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]237
Gabor Greifa3bd11d2008-06-09 06:06:18 +0000[diff] [blame]238 <p>The main features of <tt>llvmc2</tt> are:
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]239 <ul>
240 <li>Extended handling of command line options and smart rules for
241 dispatching them to different tools.</li>
242 <li>Flexible (and extensible) rules for defining different tools.</li>
243 <li>The different intermediate steps performed by tools are represented
244 as edges in the abstract graph.</li>
245 <li>The 'language' for driver behavior definition is tablegen and thus
246 it's relatively easy to add new features.</li>
247 <li>The definition of driver is transformed into set of C++ classes, thus
248 no runtime interpretation is needed.</li>
Gabor Greifa3bd11d2008-06-09 06:06:18 +0000[diff] [blame]249 </ul>
250</li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]251
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]252<li><p>LLVM 2.3 includes a completely rewritten interface for <a
253 href="LinkTimeOptimization.html">Link Time Optimization</a>. This interface
254 is written in C, which allows for easier integration with C code bases, and
255 incorporates improvements we learned about from the first incarnation of the
256 interface.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]257
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]258<li><p>The <a href="tutorial/LangImpl1.html">Kaleidoscope tutorial</a> now
259 includes a "port" of the tutorial that <a
260 href="tutorial/OCamlLangImpl1.html">uses the Ocaml bindings</a> to implement
261 the Kaleidoscope language.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]262
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]263</ul>
264
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]265</div>
266
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]267
268<!--=========================================================================-->
269<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000[diff] [blame]270<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]271</div>
272
273<div class="doc_text">
274
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]275<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end, and includes support
276for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]277
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]278<p>
279<ul>
280<li>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
281front-end. Objective-C now works very well on Mac OS/X.</li>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]282
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]283<li>Fortran <tt>EQUIVALENCE</tt>s are now supported by the gfortran
284front-end.</li>
Chris Lattner8348b472008-06-08 21:58:17 +0000[diff] [blame]285
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]286<li>llvm-gcc 4.2 includes many other fixes which improve conformance with the
287relevant parts of the GCC testsuite.</li>
288
Gabor Greifa3bd11d2008-06-09 06:06:18 +0000[diff] [blame]289</ul>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]290
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]291</div>
292
293
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]294<!--=========================================================================-->
295<div class="doc_subsection">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]296<a name="coreimprovements">LLVM Core Improvements</a>
297</div>
298
299<div class="doc_text">
300<p>New features include:
301</p>
302
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]303<ul>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]304<li>LLVM IR now directly represents "common" linkage, instead of representing it
305as a form of weak linkage.</li>
306
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]307<li>LLVM IR now has support for atomic operations, and this functionality can be
308accessed through the llvm-gcc "<tt>__sync_synchronize</tt>",
309"<tt>__sync_val_compare_and_swap</tt>", and related builtins. Support for
310atomics are available in the Alpha, X86, X86-64, and PowerPC backends.</li>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]311
312<li>The C and Ocaml bindings have extended to cover pass managers, several
313transformation passes, iteration over the LLVM IR, target data, and parameter
314attribute lists.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]315</ul>
316
317</div>
318
319<!--=========================================================================-->
320<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]321<a name="optimizer">Optimizer Improvements</a>
322</div>
323
324<div class="doc_text">
325
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]326<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]327LLVM 2.3 optimizers support a few major enhancements:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000[diff] [blame]328
329<ul>
330
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]331<li><p>Loop index set splitting on by default.
332This transformation hoists conditions from loop bodies and reduces a loop's
333iteration space to improve performance. For example,</p>
334
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]335<div class="doc_code">
Devang Patel83a15d72008-06-05 21:44:00 +0000[diff] [blame]336<pre>
Chris Lattnerc4e6b372008-06-08 20:25:30 +0000[diff] [blame]337for (i = LB; i &lt; UB; ++i)
338 if (i &lt;= NV)
Devang Patel83a15d72008-06-05 21:44:00 +0000[diff] [blame]339 LOOP_BODY
340</pre>
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]341</div>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]342
343<p>is transformed into:</p>
344
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]345<p><div class="doc_code">
Devang Patel83a15d72008-06-05 21:44:00 +0000[diff] [blame]346<pre>
347NUB = min(NV+1, UB)
Chris Lattnerc4e6b372008-06-08 20:25:30 +0000[diff] [blame]348for (i = LB; i &lt; NUB; ++i)
Devang Patel83a15d72008-06-05 21:44:00 +0000[diff] [blame]349 LOOP_BODY
350</pre>
Bill Wendling93ee81e2008-06-09 07:51:45 +0000[diff] [blame]351</div>
352</p>
Devang Patel83a15d72008-06-05 21:44:00 +0000[diff] [blame]353</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]354
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]355<li>LLVM now includes a new <tt>memcpy</tt> optimization pass which removes
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]356dead <tt>memcpy</tt> calls, unneeded copies of aggregates, and performs
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]357return slot optimization. The LLVM optimizer now notices long sequences of
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]358consecutive stores and merges them into <tt>memcpy</tt>'s where profitable.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]359
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]360<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
361<tt>memset</tt> is now more aggressive.</li>
Owen Anderson30073ff2008-06-06 16:23:15 +0000[diff] [blame]362
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]363<li>The Aggressive Dead Code Elimination (ADCE) optimization has been rewritten
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]364to make it both faster and safer in the presence of code containing infinite
365loops. Some of its prior functionality has been factored out into the loop
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]366deletion pass, which <em>is</em> safe for infinite loops. The new ADCE pass is
367no longer based on control dependence, making it run faster.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]368
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]369<li>The 'SimplifyLibCalls' pass, which optimizes calls to libc and libm
370 functions for C-based languages, has been rewritten to be a FunctionPass
371 instead a ModulePass. This allows it to be run more often and to be
372 included at -O1 in llvm-gcc. It was also extended to include more
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]373 optimizations and several corner case bugs were fixed.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]374
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]375<li>LLVM now includes a simple 'Jump Threading' pass, which attempts to simplify
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]376 conditional branches using information about predecessor blocks, simplifying
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]377 the control flow graph. This pass is pretty basic at this point, but
378 catches some important cases and provides a foundation to build on.</li>
379
380<li>Several corner case bugs which could lead to deleting volatile memory
381 accesses have been fixed.</li>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000[diff] [blame]382
383<li>Several optimizations have been sped up, leading to faster code generation
384 with the same code quality.</li>
385
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]386</ul>
387
388</div>
389
390<!--=========================================================================-->
391<div class="doc_subsection">
392<a name="codegen">Code Generator Improvements</a>
393</div>
394
395<div class="doc_text">
396
397<p>We put a significant amount of work into the code generator infrastructure,
398which allows us to implement more aggressive algorithms and make it run
399faster:</p>
400
401<ul>
Dan Gohmanfd0d22e2008-06-08 22:49:27 +0000[diff] [blame]402<li>The code generator now has support for carrying information about memory
403 references throughout the entire code generation process, via the
404 <a href="http://llvm.org/doxygen/classllvm_1_1MachineMemOperand.html">
405 MachineMemOperand</a> class. In the future this will be used to improve
406 both pre-pass and post-pass scheduling, and to improve compiler-debugging
407 output.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]408
Dan Gohmane3280782008-06-08 22:57:59 +0000[diff] [blame]409<li>The target-independent code generator infrastructure now uses LLVM's
410 <a href="http://llvm.org/doxygen/classllvm_1_1APInt.html">APInt</a>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]411 class to handle integer values, which allows it to support integer types
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]412 larger than 64 bits (for example i128). Note that support for such types is
413 also dependent on target-specific support. Use of APInt is also a step
414 toward support for non-power-of-2 integer sizes.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]415
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]416<li>LLVM 2.3 includes several compile time speedups for code with large basic
Dan Gohmaneedf6fe2008-06-08 22:44:43 +0000[diff] [blame]417 blocks, particularly in the instruction selection phase, register
418 allocation, scheduling, and tail merging/jump threading.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]419
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]420<li>LLVM 2.3 includes several improvements which make llc's
421 <tt>--view-sunit-dags</tt> visualization of scheduling dependency graphs
422 easier to understand.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]423
424<li>The code generator allows targets to write patterns that generate subreg
425 references directly in .td files now.</li>
426
427<li><tt>memcpy</tt> lowering in the backend is more aggressive, particularly for
428 <tt>memcpy</tt> calls introduced by the code generator when handling
429 pass-by-value structure argument copies.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]430
431<li>Inline assembly with multiple register results now returns those results
432 directly in the appropriate registers, rather than going through memory.
433 Inline assembly that uses constraints like "ir" with immediates now use the
434 'i' form when possible instead of always loading the value in a register.
435 This saves an instruction and reduces register use.</li>
436
Chris Lattnerf3a4fea2008-06-09 04:00:08 +0000[diff] [blame]437<li>Added support for PIC/GOT style <a
438 href="CodeGenerator.html#tailcallopt">tail calls</a> on X86/32 and initial
439 support for tail calls on PowerPC 32 (it may also work on PowerPC 64 but is
440 not thoroughly tested).</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]441</ul>
442
443</div>
444
445
446<!--=========================================================================-->
447<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]448<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]449</div>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]450
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]451<div class="doc_text">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000[diff] [blame]452<p>New target-specific features include:
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]453</p>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]454
455<ul>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]456<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]457 area of passing and returning structures by value. llvm-gcc compiled code
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]458 now interoperates very well on X86-64 systems with other compilers.</li>
459
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]460<li>Support for Win64 was added. This includes code generation itself, JIT
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]461 support, and necessary changes to llvm-gcc.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]462
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]463<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]464 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins. Various
465 generic vector operations (insert/extract/shuffle) are much more efficient
466 when SSE 4.1 is enabled. The JIT automatically takes advantage of these
467 instructions, but llvm-gcc must be explicitly told to use them, e.g. with
468 <tt>-march=penryn</tt>.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]469
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]470<li>The X86 backend now does a number of optimizations that aim to avoid
471 converting numbers back and forth from SSE registers to the X87 floating
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]472 point stack. This is important because most X86 ABIs require return values
473 to be on the X87 Floating Point stack, but most CPUs prefer computation in
474 the SSE units.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]475
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]476<li>The X86 backend supports stack realignment, which is particularly useful for
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]477 vector code on OS's without 16-byte aligned stacks, such as Linux and
478 Windows.</li>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]479
480<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
481 functions to be tagged as passing floating point values in SSE
482 registers.</li>
483
484<li>Trampolines (taking the address of a nested function) now work on
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]485 Linux/X86-64.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]486
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]487<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
488 instructions instead of being ignored.</li>
Chris Lattner791f77b2008-06-05 06:25:56 +0000[diff] [blame]489
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]490<li>128-bit integers are now supported on X86-64 targets. This can be used
491 through <tt>__attribute__((TImode))</tt> in llvm-gcc.</li>
Dan Gohman4e16d402008-06-05 16:15:39 +0000[diff] [blame]492
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]493<li>The register allocator can now rematerialize PIC-base computations, which is
494 an important optimization for register use.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000[diff] [blame]495
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]496<li>The "t" and "f" inline assembly constraints for the X87 floating point stack
497 now work. However, the "u" constraint is still not fully supported.</li>
498
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]499</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]500
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]501</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]502
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]503<!--=========================================================================-->
504<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]505<a name="targetspecific">Other Target Specific Improvements</a>
506</div>
507
508<div class="doc_text">
509<p>New target-specific features include:
510</p>
511
512<ul>
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]513<li>The LLVM C backend now supports vector code.</li>
Chris Lattner43b65e92008-06-08 23:06:47 +0000[diff] [blame]514<li>The Cell SPU backend includes a number of improvements. It generates better
515 code and its stability/completeness is improving.</li>
Chris Lattner77d29b12008-06-05 08:02:49 +0000[diff] [blame]516</ul>
517
518</div>
519
520
521
522<!--=========================================================================-->
523<div class="doc_subsection">
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]524<a name="otherimprovements">Other Improvements</a>
525</div>
526
527<div class="doc_text">
528<p>New features include:
529</p>
530
531<ul>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]532<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]533<li>Bugpoint now supports running custom scripts (with the <tt>-run-custom</tt>
534 option) to determine how to execute the command and whether it is making
535 forward process.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]536</ul>
537
538</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]539
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]540<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]541<div class="doc_section">
542 <a name="portability">Portability and Supported Platforms</a>
543</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]544<!-- *********************************************************************** -->
545
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]546<div class="doc_text">
547
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]548<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]549
550<ul>
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]551<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000[diff] [blame]552 (and probably other unix-like systems).</li>
Chris Lattner000c73b2008-02-06 06:30:34 +0000[diff] [blame]553<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]554 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]555<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]556<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
557 support is available for native builds with Visual C++).</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]558<li>Sun UltraSPARC workstations running Solaris 10.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]559<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000[diff] [blame]560<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]561</ul>
562
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000[diff] [blame]563<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]564to the machine and operating system on which it is built. However, minor
565porting may be required to get LLVM to work on new platforms. We welcome your
566portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]567
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]568</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]569
570<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]571<div class="doc_section">
572 <a name="knownproblems">Known Problems</a>
573</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]574<!-- *********************************************************************** -->
575
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]576<div class="doc_text">
577
578<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]579component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]580sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]581href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]582there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]583
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]584</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]585
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]586<!-- ======================================================================= -->
587<div class="doc_subsection">
588 <a name="experimental">Experimental features included with this release</a>
589</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]590
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]591<div class="doc_text">
592
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]593<p>The following components of this LLVM release are either untested, known to
594be broken or unreliable, or are in early development. These components should
595not be relied on, and bugs should not be filed against them, but they may be
596useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]597components, please contact us on the <a
598href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]599
600<ul>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]601<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]602<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattner000c73b2008-02-06 06:30:34 +0000[diff] [blame]603 value for this option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]604</ul>
605
606</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]607
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]608<!-- ======================================================================= -->
609<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]610 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]611</div>
612
613<div class="doc_text">
614
615<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]616 <li>The X86 backend does not yet support
617 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
618 floating point stack</a>. It supports the 'f' and 't' constraints, but not
619 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]620 <li>The X86 backend generates inefficient floating point code when configured
621 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000[diff] [blame]622 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000[diff] [blame]623 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
624 currently due
625 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000[diff] [blame]626 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
627 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000[diff] [blame]628 <li>The X86-64 backend does not yet support position-independent code (PIC)
629 generation on Linux targets.</li>
630 <li>The X86-64 backend does not yet support the LLVM IR instruction
631 <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
632 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]633</ul>
634
635</div>
636
637<!-- ======================================================================= -->
638<div class="doc_subsection">
639 <a name="ppc-be">Known problems with the PowerPC back-end</a>
640</div>
641
642<div class="doc_text">
643
644<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]645<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]646compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]647</ul>
648
649</div>
650
651<!-- ======================================================================= -->
652<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]653 <a name="arm-be">Known problems with the ARM back-end</a>
654</div>
655
656<div class="doc_text">
657
658<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]659<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]660processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]661results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]662<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
663</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]664<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
665 execute
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]666programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]667</ul>
668
669</div>
670
671<!-- ======================================================================= -->
672<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]673 <a name="sparc-be">Known problems with the SPARC back-end</a>
674</div>
675
676<div class="doc_text">
677
678<ul>
679<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
680 support the 64-bit SPARC ABI (-m64).</li>
681</ul>
682
683</div>
684
685<!-- ======================================================================= -->
686<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]687 <a name="alpha-be">Known problems with the Alpha back-end</a>
688</div>
689
690<div class="doc_text">
691
692<ul>
693
694<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
695appropriate nops inserted to ensure restartability.</li>
696
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]697</ul>
698</div>
699
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]700<!-- ======================================================================= -->
701<div class="doc_subsection">
702 <a name="ia64-be">Known problems with the IA64 back-end</a>
703</div>
704
705<div class="doc_text">
706
707<ul>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000[diff] [blame]708<li>The Itanium backend is highly experimental, and has a number of known
709 issues. We are looking for a maintainer for the Itanium backend. If you
710 are interested, please contact the llvmdev mailing list.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]711</ul>
712
713</div>
714
715<!-- ======================================================================= -->
716<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]717 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]718</div>
719
720<div class="doc_text">
721
722<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]723<li><a href="http://llvm.org/PR802">The C backend has only basic support for
724 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]725<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
726 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]727 C++ code compiled with llc or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000[diff] [blame]728<li>The C backend does not support all exception handling constructs.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]729</ul>
730
731</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]732
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]733
734<!-- ======================================================================= -->
735<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]736 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]737</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]738
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]739<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]740
Chris Lattner252b83d2008-02-06 18:00:06 +0000[diff] [blame]741<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
742Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]743llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000[diff] [blame]744
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]745<p>The only major language feature of GCC not supported by llvm-gcc is
746 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
747 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]748 supported on some targets (these are used when you take the address of a
749 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]750
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]751<p>If you run into GCC extensions which are not supported, please let us know.
752</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]753
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]754</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]755
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]756<!-- ======================================================================= -->
757<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]758 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]759</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]760
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]761<div class="doc_text">
762
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]763<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]764tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]765itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]766
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]767<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]768<li>Exception handling works well on the X86 and PowerPC targets, including
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]769X86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
770supported on X86-64 linux, but that is disabled by default in this release.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]771</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]772
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]773</div>
774
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]775
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]776<!-- ======================================================================= -->
777<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000[diff] [blame]778 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]779</div>
780
781<div class="doc_text">
782The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
783technology and problems should be expected.
784<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]785<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]786to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]787however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]788which does support trampolines.</li>
789<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
790Workaround: configure with --disable-bootstrap.</li>
791<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
Duncan Sands27aff872008-06-08 20:18:35 +0000[diff] [blame]792fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
793<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
794<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
795reports most tests as having failed even though they pass.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]796<li>The -E binder option (exception backtraces)
797<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
798crashing if an exception is raised. Workaround: do not use -E.</li>
799<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
800or finish at a non-byte offset</a> in a record. Workaround: do not pack records
801or use representation clauses that result in a field of a non-discrete type
802starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000[diff] [blame]803<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
804'main' as generated by the Ada binder to be invalid</a>.
805Workaround: hand edit the file to use pointers for <tt>argv</tt> and
806<tt>envp</tt> rather than integers.</li>
807<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
808ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000[diff] [blame]809</ul>
810</div>
811
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]812<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]813<div class="doc_section">
814 <a name="additionalinfo">Additional Information</a>
815</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]816<!-- *********************************************************************** -->
817
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]818<div class="doc_text">
819
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]820<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]821href="http://llvm.org">LLVM web page</a>, in particular in the <a
822href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]823contains versions of the API documentation which is up-to-date with the
824Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]825You can access versions of these documents specific to this release by going
826into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]827
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]828<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]829us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]830lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]831
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]832</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]833
834<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]835
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]836<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]837<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]838 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]839 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
840 <a href="http://validator.w3.org/check/referer"><img
Chris Lattner8170c102008-02-10 08:18:42 +0000[diff] [blame]841 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]842
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]843 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]844 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]845</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]846
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]847</body>
848</html>