blob: afa0619f31569b0a463af53abf57387c9059a195 [file] [log] [blame]
Anton Korobeynikov0d176912008-06-08 10:23:46 +00001
Misha Brukman500bc302003-11-22 00:38:41 +00002<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
3 "http://www.w3.org/TR/html4/strict.dtd">
4<html>
5<head>
Reid Spencer6454ed32004-11-18 18:38:58 +00006 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman500bc302003-11-22 00:38:41 +00007 <link rel="stylesheet" href="llvm.css" type="text/css">
Chris Lattner2b659ef2008-02-12 06:29:45 +00008 <title>LLVM 2.3 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +00009</head>
10<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +000011
Chris Lattner2b659ef2008-02-12 06:29:45 +000012<div class="doc_title">LLVM 2.3 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000013
14<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000015 <li><a href="#intro">Introduction</a></li>
16 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +000017 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +000018 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000019 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +000020 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000021</ol>
22
Chris Lattner7911ce22004-05-23 21:07:27 +000023<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +000024 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +000025</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000026
Chris Lattner77d29b12008-06-05 08:02:49 +000027<!-- Done through Week-of-Mon-20080324.txt -->
28
Chris Lattner79c3fe12003-10-02 04:57:28 +000029<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000030<div class="doc_section">
31 <a name="intro">Introduction</a>
32</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000033<!-- *********************************************************************** -->
34
Misha Brukman500bc302003-11-22 00:38:41 +000035<div class="doc_text">
36
37<p>This document contains the release notes for the LLVM compiler
Chris Lattner2b659ef2008-02-12 06:29:45 +000038infrastructure, release 2.3. Here we describe the status of LLVM, including
Chris Lattner57a460e2007-05-23 04:39:32 +000039major improvements from the previous release and any known problems. All LLVM
Chris Lattnercaf06342007-05-09 04:58:11 +000040releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
Chris Lattner57a460e2007-05-23 04:39:32 +000041releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +000042
Chris Lattner7506b1d2004-12-07 08:04:13 +000043<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000044release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000045web site</a>. If you have questions or comments, the <a
46href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +000047list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000048
Reid Spencer669ed452007-07-09 08:04:31 +000049<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +000050main LLVM web page, this document applies to the <i>next</i> release, not the
51current one. To see the release notes for a specific releases, please see the
52<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +000053
54</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000055
56<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000057<div class="doc_section">
58 <a name="whatsnew">What's New?</a>
59</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000060<!-- *********************************************************************** -->
61
Misha Brukman500bc302003-11-22 00:38:41 +000062<div class="doc_text">
63
Chris Lattner2b659ef2008-02-12 06:29:45 +000064<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
Chris Lattner791f77b2008-06-05 06:25:56 +000065It includes a large number of features and refinements from LLVM 2.2.</p>
Chris Lattnera5099962003-12-06 20:22:41 +000066
Chris Lattner80453c92004-05-24 04:50:25 +000067</div>
68
Chris Lattner2b659ef2008-02-12 06:29:45 +000069<!-- Unfinished features in 2.3:
Chris Lattneracce85d2008-02-10 07:46:44 +000070 Machine LICM
71 Machine Sinking
72 LegalizeDAGTypes
73 -->
74
Chris Lattnera5099962003-12-06 20:22:41 +000075<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +000076<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +000077<a name="changes">Major Changes in LLVM 2.3</a>
Chris Lattnerb4c68cd2008-02-10 07:04:35 +000078</div>
79
80<div class="doc_text">
81
Chris Lattnerea34f642008-06-08 21:34:41 +000082<p>LLVM 2.3 no longer supports llvm-gcc 4.0, it has been replaced with
83 llvm-gcc 4.2.</p>
Chris Lattner252b83d2008-02-06 18:00:06 +000084
Chris Lattnerea34f642008-06-08 21:34:41 +000085<p>LLVM 2.3 no longer includes the <tt>llvm-upgrade</tt> tool. It was useful
86 for upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a
87 previous LLVM release to do this. One nice impact of this is that the LLVM
88 regression test suite no longer depends on llvm-upgrade, which makes it run
89 faster.</p>
90
91<p>The <tt>llvm2cpp</tt> tool has been folded into llc, use
Chris Lattnere6e1b352008-06-08 21:19:07 +000092 <tt>llc -march=cpp</tt> instead of <tt>llvm2cpp</tt>.</p>
93
Chris Lattner0b832202008-06-08 02:45:07 +000094<p>LLVM API Changes:</p>
Chris Lattner77d29b12008-06-05 08:02:49 +000095
Chris Lattner0b832202008-06-08 02:45:07 +000096<ul>
Chris Lattnerea34f642008-06-08 21:34:41 +000097<li>Several core LLVM IR classes have migrated to use the
98 '<tt>FOOCLASS::Create(...)</tt>' pattern instead of '<tt>new
99 FOOCLASS(...)</tt>' (e.g. where FOOCLASS=<tt>BasicBlock</tt>). We hope to
100 standardize on <tt>FOOCLASS::Create</tt> for all IR classes in the future,
101 but not all of them have been moved over yet.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000102<li>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
103 IRBuilder.</li>
104<li>MRegisterInfo was renamed to TargetRegisterInfo.</li>
105<li>The MappedFile class is gone, please use MemoryBuffer instead.</li>
Chris Lattnerea34f642008-06-08 21:34:41 +0000106<li>The '<tt>-enable-eh</tt>' flag to llc has been removed. Now code should
107 encode whether it is safe to omit unwind information for a function by
108 tagging the Function object with the '<tt>nounwind</tt>' attribute.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000109
110</ul>
Chris Lattner252b83d2008-02-06 18:00:06 +0000111</div>
112
113<!--=========================================================================-->
114<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000115<a name="otherprojects">Other LLVM Sub-Projects</a>
116</div>
117
118<div class="doc_text">
119
120<p>
121<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
122a set of new 'llvm native' front-end technologies for the LLVM optimizer
123and code generator. Currently, its C and Objective-C support is maturing
124nicely, and it has advanced source-to-source analysis and transformation
125capabilities. If you are interested in building source-level tools for C and
126Objective-C (and eventually C++), you should take a look. However, note that
127clang is not an official part of the LLVM 2.3 release. If you are interested in
128this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
129
130
131</p>
132
133</div>
134
135<!--=========================================================================-->
136<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000137<a name="majorfeatures">Major New Features</a>
138</div>
139
140<div class="doc_text">
141
Chris Lattner2b659ef2008-02-12 06:29:45 +0000142<p>LLVM 2.3 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000143
144<ul>
Chris Lattnerea34f642008-06-08 21:34:41 +0000145<li><p>The biggest change in LLVM 2.3 is Multiple Return Value (MRV) support.
146 MRVs allow LLVM IR to directly represent functions that return multiple
147 values without having to pass them "by reference" in the LLVM IR. This
148 allows a front-end to generate more efficient code, as MRVs are generally
149 returned in registers if a target supports them. See the <a
150 href="LangRef.html#i_getresult">LLVM IR Reference</a> for more details.</p>
151
152 <p>MRVs are fully supported in the LLVM IR, but are not yet fully supported in
153 on all targets. However, it is generally safe to return up to 2 values from
154 a function: most targets should be able to handle at least that. MRV
155 support is a critical requirement for X86-64 ABI support, as X86-64 requires
156 the ability to return multiple registers from functions, and we use MRVs to
157 accomplish this in a direct way.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000158
159
Chris Lattnerea34f642008-06-08 21:34:41 +0000160<li><p>LLVM 2.3 includes a complete reimplementation of the "<tt>llvmc</tt>"
161 tool. It is designed to overcome several problems with the original
162 <tt>llvmc</tt> and to provide a superset of the features of the
163 '<tt>gcc</tt>' driver.</p>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000164
Chris Lattnerea34f642008-06-08 21:34:41 +0000165<p>The main features of <tt>llvmc2</tt> are:
166 <ul>
167 <li>Extended handling of command line options and smart rules for
168 dispatching them to different tools.</li>
169 <li>Flexible (and extensible) rules for defining different tools.</li>
170 <li>The different intermediate steps performed by tools are represented
171 as edges in the abstract graph.</li>
172 <li>The 'language' for driver behavior definition is tablegen and thus
173 it's relatively easy to add new features.</li>
174 <li>The definition of driver is transformed into set of C++ classes, thus
175 no runtime interpretation is needed.</li>
176 </ul></p>
177 </li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000178
Gabor Greif96a89c72008-06-05 18:39:01 +0000179
Chris Lattnerea34f642008-06-08 21:34:41 +0000180<li><p>LLVM 2.3 includes a completely rewritten interface for <a
181 href="LinkTimeOptimization.html">Link Time Optimization</a>. This interface
182 is written in C, which allows for easier integration with C code bases, and
183 incorporates improvements we learned about from the first incarnation of the
184 interface.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000185
Chris Lattnerea34f642008-06-08 21:34:41 +0000186<li><p>The <a href="tutorial/LangImpl1.html">Kaleidoscope tutorial</a> now
187 includes a "port" of the tutorial that <a
188 href="tutorial/OCamlLangImpl1.html">uses the Ocaml bindings</a> to implement
189 the Kaleidoscope language.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000190
Chris Lattner8170c102008-02-10 08:18:42 +0000191</ul>
192
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000193</div>
194
Chris Lattner791f77b2008-06-05 06:25:56 +0000195
196<!--=========================================================================-->
197<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000198<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattner791f77b2008-06-05 06:25:56 +0000199</div>
200
201<div class="doc_text">
202
Duncan Sands27aff872008-06-08 20:18:35 +0000203<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end.</p>
Chris Lattner791f77b2008-06-05 06:25:56 +0000204
205<p>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
206front-end. Objective-C now works very well on Mac OS/X.</p>
207
208<p>llvm-gcc 4.2 includes many other fixes which improve conformance with the
209relevant parts of the GCC testsuite.</p>
210
Chris Lattner791f77b2008-06-05 06:25:56 +0000211</div>
212
213
Chris Lattner84977642007-09-21 03:54:09 +0000214<!--=========================================================================-->
215<div class="doc_subsection">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000216<a name="coreimprovements">LLVM Core Improvements</a>
217</div>
218
219<div class="doc_text">
220<p>New features include:
221</p>
222
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000223
Chris Lattner791f77b2008-06-05 06:25:56 +0000224Common linkage?
225
Chris Lattner0b832202008-06-08 02:45:07 +0000226Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize",
Anton Korobeynikov0d176912008-06-08 10:23:46 +0000227"__sync_val_compare_and_swap", etc
Chris Lattner791f77b2008-06-05 06:25:56 +0000228
229<ul>
Gordon Henriksen1494bcc2008-06-05 12:51:50 +0000230<li>The C and Ocaml bindings have received additional improvements. The
231bindings now cover pass managers, several transformation passes, iteration
232over the LLVM IR, target data, and parameter attribute lists.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000233</ul>
234
235</div>
236
237<!--=========================================================================-->
238<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000239<a name="optimizer">Optimizer Improvements</a>
240</div>
241
242<div class="doc_text">
243
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000244<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner2b659ef2008-02-12 06:29:45 +0000245LLVM 2.3 optimizers support a few major enhancements:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000246
247<ul>
248
Devang Patel83a15d72008-06-05 21:44:00 +0000249<li>Loop index set splitting on by default.<p>
250This transformation hoists conditions from loop bodies and reduces loop's
251iteration space to improve performance. For example, <p>
252<pre>
Chris Lattnerc4e6b372008-06-08 20:25:30 +0000253for (i = LB; i &lt; UB; ++i)
254 if (i &lt;= NV)
Devang Patel83a15d72008-06-05 21:44:00 +0000255 LOOP_BODY
256</pre>
257is transformed into
258<pre>
259NUB = min(NV+1, UB)
Chris Lattnerc4e6b372008-06-08 20:25:30 +0000260for (i = LB; i &lt; NUB; ++i)
Devang Patel83a15d72008-06-05 21:44:00 +0000261 LOOP_BODY
262</pre>
263</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000264
Duncan Sands27aff872008-06-08 20:18:35 +0000265<li>LLVM includes a new <tt>memcpy</tt> optimization pass removes
266dead <tt>memcpy</tt> calls, unneeded copies of aggregates, and performs
Chris Lattner0b832202008-06-08 02:45:07 +0000267return slot optimization. The LLVM optimizer now notices long sequences of
Duncan Sands27aff872008-06-08 20:18:35 +0000268consecutive stores and merges them into <tt>memcpy</tt>'s where profitable.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000269
Gabor Greif96a89c72008-06-05 18:39:01 +0000270<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
271<tt>memset</tt> is now more aggressive.</li>
Owen Anderson30073ff2008-06-06 16:23:15 +0000272
Chris Lattner0b832202008-06-08 02:45:07 +0000273<li>The aggressive dead code elimination (ADCE) optimization has been rewritten
274to make it both faster and safer in the presence of code containing infinite
275loops. Some of its prior functionality has been factored out into the loop
276deletion pass, which <em>is</em> safe for infinite loops.</li>
277
278<li>Several optimizations have been sped up, leading to faster code generation
279 with the same code quality.</li>
280
281<li>The 'SimplifyLibCalls' pass, which optimizes calls to libc and libm
282 functions for C-based languages, has been rewritten to be a FunctionPass
283 instead a ModulePass. This allows it to be run more often and to be
284 included at -O1 in llvm-gcc. It was also extended to include more
Duncan Sands27aff872008-06-08 20:18:35 +0000285 optimizations and several corner case bugs were fixed.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000286
Duncan Sands47eff2b2008-06-08 19:38:43 +0000287<li>LLVM now includes a simple 'Jump Threading' pass, which attempts to simplify
Duncan Sands27aff872008-06-08 20:18:35 +0000288 conditional branches using information about predecessor blocks, simplifying
Chris Lattnere6e1b352008-06-08 21:19:07 +0000289 the control flow graph. This pass is pretty basic at this point, but
290 catches some important cases and provides a foundation to build on.</li>
291
292<li>Several corner case bugs which could lead to deleting volatile memory
293 accesses have been fixed.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000294</ul>
295
296</div>
297
298<!--=========================================================================-->
299<div class="doc_subsection">
300<a name="codegen">Code Generator Improvements</a>
301</div>
302
303<div class="doc_text">
304
305<p>We put a significant amount of work into the code generator infrastructure,
306which allows us to implement more aggressive algorithms and make it run
307faster:</p>
308
309<ul>
310<li>MemOperand in the code generator: describe me!.</li>
311
312<li>The target-independent code generator infrastructure now uses LLVM's APInt
313 class to handle integer values, which allows it to support integer types
314 larger than 64 bits. Note that support for such types is also dependent on
315 target-specific support. Use of APInt is also a step toward support for
316 non-power-of-2 integer sizes.</li>
317
Chris Lattnere6e1b352008-06-08 21:19:07 +0000318<li>LLVM 2.3 includes several compile time speedups for code with large basic
319 blocks, particular in the instruction selection phase, register allocation,
320 scheduling, and tail merging/jump threading.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000321
322<li>Several improvements which make llc's <tt>--view-sunit-dags</tt>
323 visualization of scheduling dependency graphs easier to understand.</li>
324
325<li>The code generator allows targets to write patterns that generate subreg
326 references directly in .td files now.</li>
327
328<li><tt>memcpy</tt> lowering in the backend is more aggressive, particularly for
329 <tt>memcpy</tt> calls introduced by the code generator when handling
330 pass-by-value structure argument copies.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000331
332<li>Inline assembly with multiple register results now returns those results
333 directly in the appropriate registers, rather than going through memory.
334 Inline assembly that uses constraints like "ir" with immediates now use the
335 'i' form when possible instead of always loading the value in a register.
336 This saves an instruction and reduces register use.</li>
337
338<li>Added support for PIC/GOT style tail calls on x86/32 and initial support
339 for tail calls on PowerPC 32 (it may also work on ppc64 but not
340 thoroughly tested).</li>
Chris Lattner84977642007-09-21 03:54:09 +0000341</ul>
342
343</div>
344
345
346<!--=========================================================================-->
347<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000348<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattner84977642007-09-21 03:54:09 +0000349</div>
Chris Lattner60893e52007-05-18 06:33:02 +0000350
Chris Lattner738bd302006-04-18 06:32:08 +0000351<div class="doc_text">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000352<p>New target-specific features include:
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000353</p>
Chris Lattner26299222006-11-18 07:51:14 +0000354
355<ul>
Chris Lattner791f77b2008-06-05 06:25:56 +0000356<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
Gabor Greif96a89c72008-06-05 18:39:01 +0000357 area of passing and returning structures by value. llvm-gcc compiled code
Chris Lattner791f77b2008-06-05 06:25:56 +0000358 now interoperates very well on X86-64 systems with other compilers.</li>
359
Duncan Sands47eff2b2008-06-08 19:38:43 +0000360<li>Support for Win64 was added. This includes code generation itself, JIT
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000361 support and necessary changes to llvm-gcc.</li>
362
Chris Lattner791f77b2008-06-05 06:25:56 +0000363<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
Chris Lattner0b832202008-06-08 02:45:07 +0000364 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins. Various
365 generic vector operations (insert/extract/shuffle) are much more efficient
366 when SSE 4.1 is enabled. The JIT automatically takes advantage of these
367 instructions, but llvm-gcc must be explicitly told to use them, e.g. with
368 <tt>-march=penryn</tt>.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000369
Chris Lattner791f77b2008-06-05 06:25:56 +0000370<li>The X86 backend now does a number of optimizations that aim to avoid
371 converting numbers back and forth from SSE registers to the X87 floating
372 point stack.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000373
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000374<li>The X86 backend supports stack realignment, which is particularly useful for
375 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattner791f77b2008-06-05 06:25:56 +0000376
377<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
378 functions to be tagged as passing floating point values in SSE
379 registers.</li>
380
381<li>Trampolines (taking the address of a nested function) now work on
Duncan Sands27aff872008-06-08 20:18:35 +0000382 Linux/X86-64.</li>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000383
Chris Lattner77d29b12008-06-05 08:02:49 +0000384<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
385 instructions instead of being ignored.</li>
Chris Lattner791f77b2008-06-05 06:25:56 +0000386
Duncan Sands27aff872008-06-08 20:18:35 +0000387<li>128-bit integers are now supported on X86-64 targets.</li>
Dan Gohman4e16d402008-06-05 16:15:39 +0000388
Chris Lattner0b832202008-06-08 02:45:07 +0000389<li>The register allocator can now rematerialize PIC-base computations.</li>
390
Chris Lattnere6e1b352008-06-08 21:19:07 +0000391<li>The "t" and "f" inline assembly constraints for the X87 floating point stack
392 now work. However, the "u" constraint is still not fully supported.</li>
393
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000394</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000395
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000396</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000397
Chris Lattner84977642007-09-21 03:54:09 +0000398<!--=========================================================================-->
399<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000400<a name="targetspecific">Other Target Specific Improvements</a>
401</div>
402
403<div class="doc_text">
404<p>New target-specific features include:
405</p>
406
407<ul>
Gabor Greif96a89c72008-06-05 18:39:01 +0000408<li>The LLVM C backend now supports vector code.</li>
Chris Lattner77d29b12008-06-05 08:02:49 +0000409</ul>
410
411</div>
412
413
414
415<!--=========================================================================-->
416<div class="doc_subsection">
Chris Lattner84977642007-09-21 03:54:09 +0000417<a name="otherimprovements">Other Improvements</a>
418</div>
419
420<div class="doc_text">
421<p>New features include:
422</p>
423
424<ul>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000425<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000426<li>Bugpoint now supports running custom scripts (with the <tt>-run-custom</tt>
427 option) to determine how to execute the command and whether it is making
428 forward process.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000429</ul>
430
431</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000432
Chris Lattner19092612003-10-02 16:38:05 +0000433<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000434<div class="doc_section">
435 <a name="portability">Portability and Supported Platforms</a>
436</div>
Chris Lattner19092612003-10-02 16:38:05 +0000437<!-- *********************************************************************** -->
438
Misha Brukman500bc302003-11-22 00:38:41 +0000439<div class="doc_text">
440
John Criswell0b5b5e92004-12-08 20:35:47 +0000441<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000442
443<ul>
Gabor Greif96a89c72008-06-05 18:39:01 +0000444<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000445 (and probably other unix-like systems).</li>
Chris Lattner000c73b2008-02-06 06:30:34 +0000446<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 +0000447 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000448<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000449<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
450 support is available for native builds with Visual C++).</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000451<li>Sun UltraSPARC workstations running Solaris 10.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000452<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000453<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000454</ul>
455
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000456<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000457to the machine and operating system on which it is built. However, minor
458porting may be required to get LLVM to work on new platforms. We welcome your
459portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000460
Misha Brukman500bc302003-11-22 00:38:41 +0000461</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000462
463<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000464<div class="doc_section">
465 <a name="knownproblems">Known Problems</a>
466</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000467<!-- *********************************************************************** -->
468
Misha Brukman500bc302003-11-22 00:38:41 +0000469<div class="doc_text">
470
471<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000472component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000473sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000474href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000475there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000476
Misha Brukman500bc302003-11-22 00:38:41 +0000477</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000478
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000479<!-- ======================================================================= -->
480<div class="doc_subsection">
481 <a name="experimental">Experimental features included with this release</a>
482</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000483
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000484<div class="doc_text">
485
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000486<p>The following components of this LLVM release are either untested, known to
487be broken or unreliable, or are in early development. These components should
488not be relied on, and bugs should not be filed against them, but they may be
489useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000490components, please contact us on the <a
491href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000492
493<ul>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000494<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sands27aff872008-06-08 20:18:35 +0000495<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattner000c73b2008-02-06 06:30:34 +0000496 value for this option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000497</ul>
498
499</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000500
Misha Brukman500bc302003-11-22 00:38:41 +0000501<!-- ======================================================================= -->
502<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000503 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000504</div>
505
506<div class="doc_text">
507
508<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000509 <li>The X86 backend does not yet support
510 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
511 floating point stack</a>. It supports the 'f' and 't' constraints, but not
512 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000513 <li>The X86 backend generates inefficient floating point code when configured
514 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000515 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000516 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
517 currently due
518 to <a href="http://llvm.org/PR2255">several</a>
519 <a href="http://llvm.org/PR2257">bugs</a> in FP stackifier
Chris Lattner26299222006-11-18 07:51:14 +0000520</ul>
521
522</div>
523
524<!-- ======================================================================= -->
525<div class="doc_subsection">
526 <a name="ppc-be">Known problems with the PowerPC back-end</a>
527</div>
528
529<div class="doc_text">
530
531<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000532<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000533compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000534</ul>
535
536</div>
537
538<!-- ======================================================================= -->
539<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000540 <a name="arm-be">Known problems with the ARM back-end</a>
541</div>
542
543<div class="doc_text">
544
545<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000546<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000547processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000548results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000549<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
550</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000551<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
552 execute
Chris Lattner57a460e2007-05-23 04:39:32 +0000553programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000554</ul>
555
556</div>
557
558<!-- ======================================================================= -->
559<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000560 <a name="sparc-be">Known problems with the SPARC back-end</a>
561</div>
562
563<div class="doc_text">
564
565<ul>
566<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
567 support the 64-bit SPARC ABI (-m64).</li>
568</ul>
569
570</div>
571
572<!-- ======================================================================= -->
573<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000574 <a name="alpha-be">Known problems with the Alpha back-end</a>
575</div>
576
577<div class="doc_text">
578
579<ul>
580
581<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
582appropriate nops inserted to ensure restartability.</li>
583
John Criswellc0c186d2005-11-08 21:11:33 +0000584</ul>
585</div>
586
Chris Lattner26299222006-11-18 07:51:14 +0000587<!-- ======================================================================= -->
588<div class="doc_subsection">
589 <a name="ia64-be">Known problems with the IA64 back-end</a>
590</div>
591
592<div class="doc_text">
593
594<ul>
595
596<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
597made where the argument is not 16-byte aligned, as required on IA64. (Strictly
598speaking this is not a bug in the IA64 back-end; it will also be encountered
599when building C++ programs using the C back-end.)</li>
600
601<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
602ABI compliant layout of v-tables</a>. In particular, it just stores function
603pointers instead of function descriptors in the vtable. This bug prevents
604mixing C++ code compiled with LLVM with C++ objects compiled by other C++
605compilers.</li>
606
607<li>There are a few ABI violations which will lead to problems when mixing LLVM
608output with code built with other compilers, particularly for floating-point
609programs.</li>
610
Duncan Sands47eff2b2008-06-08 19:38:43 +0000611<li>Defining vararg functions is not supported (but calling them is OK).</li>
Chris Lattner26299222006-11-18 07:51:14 +0000612
Chris Lattnercaf06342007-05-09 04:58:11 +0000613<li>The Itanium backend has bitrotted somewhat.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000614</ul>
615
616</div>
617
618<!-- ======================================================================= -->
619<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000620 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000621</div>
622
623<div class="doc_text">
624
625<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000626<li><a href="http://llvm.org/PR802">The C backend has only basic support for
627 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000628<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
629 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sands27aff872008-06-08 20:18:35 +0000630 C++ code compiled with llc or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000631<li>The C backend does not support all exception handling constructs.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000632</ul>
633
634</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000635
Misha Brukman500bc302003-11-22 00:38:41 +0000636
637<!-- ======================================================================= -->
638<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000639 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000640</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000641
Chris Lattner79c3fe12003-10-02 04:57:28 +0000642<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000643<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000644
Misha Brukman500bc302003-11-22 00:38:41 +0000645<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000646
Chris Lattner252b83d2008-02-06 18:00:06 +0000647<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
648Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000649llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000650
Chris Lattner5733b272008-06-05 06:35:40 +0000651<p>The only major language feature of GCC not supported by llvm-gcc is
652 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
653 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000654 supported on some targets (these are used when you take the address of a
655 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000656
Chris Lattner5733b272008-06-05 06:35:40 +0000657<p>If you run into GCC extensions which are not supported, please let us know.
658</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000659
Misha Brukman500bc302003-11-22 00:38:41 +0000660</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000661
Misha Brukman500bc302003-11-22 00:38:41 +0000662<!-- ======================================================================= -->
663<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000664 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000665</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000666
Misha Brukman500bc302003-11-22 00:38:41 +0000667<div class="doc_text">
668
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000669<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000670tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000671itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000672
Misha Brukman500bc302003-11-22 00:38:41 +0000673<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000674<li>Exception handling works well on the X86 and PowerPC targets, including
Duncan Sands27aff872008-06-08 20:18:35 +0000675X86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
676supported on X86-64 linux, but that is disabled by default in this release.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000677</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000678
Misha Brukman500bc302003-11-22 00:38:41 +0000679</div>
680
Misha Brukman500bc302003-11-22 00:38:41 +0000681
Chris Lattner2b659ef2008-02-12 06:29:45 +0000682<!-- ======================================================================= -->
683<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000684 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000685</div>
686
687<div class="doc_text">
688The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
689technology and problems should be expected.
690<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000691<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattner2b659ef2008-02-12 06:29:45 +0000692to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sands27aff872008-06-08 20:18:35 +0000693however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000694which does support trampolines.</li>
695<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
696Workaround: configure with --disable-bootstrap.</li>
697<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
Duncan Sands27aff872008-06-08 20:18:35 +0000698fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
699<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
700<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
701reports most tests as having failed even though they pass.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000702<li>The -E binder option (exception backtraces)
703<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
704crashing if an exception is raised. Workaround: do not use -E.</li>
705<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
706or finish at a non-byte offset</a> in a record. Workaround: do not pack records
707or use representation clauses that result in a field of a non-discrete type
708starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000709<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
710'main' as generated by the Ada binder to be invalid</a>.
711Workaround: hand edit the file to use pointers for <tt>argv</tt> and
712<tt>envp</tt> rather than integers.</li>
713<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
714ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000715</ul>
716</div>
717
Chris Lattner79c3fe12003-10-02 04:57:28 +0000718<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000719<div class="doc_section">
720 <a name="additionalinfo">Additional Information</a>
721</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000722<!-- *********************************************************************** -->
723
Misha Brukman500bc302003-11-22 00:38:41 +0000724<div class="doc_text">
725
Chris Lattner416db102005-05-16 17:13:10 +0000726<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000727href="http://llvm.org">LLVM web page</a>, in particular in the <a
728href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000729contains versions of the API documentation which is up-to-date with the
730Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000731You can access versions of these documents specific to this release by going
732into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000733
Misha Brukman500bc302003-11-22 00:38:41 +0000734<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000735us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000736lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000737
Misha Brukman500bc302003-11-22 00:38:41 +0000738</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000739
740<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000741
Misha Brukman500bc302003-11-22 00:38:41 +0000742<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000743<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000744 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000745 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
746 <a href="http://validator.w3.org/check/referer"><img
Chris Lattner8170c102008-02-10 08:18:42 +0000747 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Misha Brukman2061e892003-11-22 01:23:39 +0000748
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000749 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000750 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000751</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000752
Misha Brukman500bc302003-11-22 00:38:41 +0000753</body>
754</html>