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Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]8 <title>LLVM 2.3 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]9</head>
10<body>
11
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]12<div class="doc_title">LLVM 2.3 Release Notes</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]13
14<ol>
15 <li><a href="#intro">Introduction</a></li>
16 <li><a href="#whatsnew">What's New?</a></li>
17 <li><a href="GettingStarted.html">Installation Instructions</a></li>
18 <li><a href="#portability">Portability and Supported Platforms</a></li>
19 <li><a href="#knownproblems">Known Problems</a>
20 <li><a href="#additionalinfo">Additional Information</a></li>
21</ol>
22
23<div class="doc_author">
24 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
25</div>
26
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]27<!-- Done through Week-of-Mon-20080324.txt -->
28
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]29<!-- *********************************************************************** -->
30<div class="doc_section">
31 <a name="intro">Introduction</a>
32</div>
33<!-- *********************************************************************** -->
34
35<div class="doc_text">
36
37<p>This document contains the release notes for the LLVM compiler
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]38infrastructure, release 2.3. Here we describe the status of LLVM, including
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]39major improvements from the previous release and any known problems. All LLVM
40releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
41releases web site</a>.</p>
42
43<p>For more information about LLVM, including information about the latest
44release, please check out the <a href="http://llvm.org/">main LLVM
45web site</a>. If you have questions or comments, the <a
46href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
47list</a> is a good place to send them.</p>
48
49<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]50main 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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]53
54</div>
55
56<!-- *********************************************************************** -->
57<div class="doc_section">
58 <a name="whatsnew">What's New?</a>
59</div>
60<!-- *********************************************************************** -->
61
62<div class="doc_text">
63
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]64<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]65It includes a large number of features and refinements from LLVM 2.2.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]66
67</div>
68
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]69<!-- Unfinished features in 2.3:
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]70 Machine LICM
71 Machine Sinking
72 LegalizeDAGTypes
73 -->
74
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]75<!--=========================================================================-->
76<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]77<a name="changes">Major Changes in LLVM 2.3</a>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]78</div>
79
80<div class="doc_text">
81
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]82<p>LLVM 2.2 was the last LLVM release to support llvm-gcc 4.0 and llvm-upgrade.
83llvm-gcc 4.0 has been replaced with llvm-gcc 4.2. llvm-upgrade was useful for
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]84upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a previous
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]85LLVM release to do this. One nice impact of this is that the LLVM regression
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]86test suite no longer depends on llvm-upgrade, which makes it run faster.</p>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]87
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]88<p><tt>llvm2cpp</tt> tool has been folded into llc, use
89 <tt>llc -march=cpp</tt> instead of <tt>llvm2cpp</tt>.</p>
90
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]91<p>LLVM API Changes:</p>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]92
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]93<ul>
94<li>Several core LLVM IR classes have migrated to use 'FOOCLASS::Create(...)'
95 instead of 'new FOOCLASS(...)' (e.g. where FOOCLASS=BasicBlock). We hope to
96 standardize on FOOCLASS::Create for all IR classes in the future, but not
97 all of them have been moved over yet.</li>
98<li>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
99 IRBuilder.</li>
100<li>MRegisterInfo was renamed to TargetRegisterInfo.</li>
101<li>The MappedFile class is gone, please use MemoryBuffer instead.</li>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]102<li>The '-enable-eh' flag to llc has been removed. Now code should encode
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]103 whether it is safe to not generate unwind information for a function by
104 tagging the Function object with the 'nounwind' attribute.</li>
105
106</ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]107</div>
108
109<!--=========================================================================-->
110<div class="doc_subsection">
111<a name="majorfeatures">Major New Features</a>
112</div>
113
114<div class="doc_text">
115
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]116<p>LLVM 2.3 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]117
118<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]119<li>Multiple Return Value Support.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]120
121
122<li><p>LLVM 2.3 includes a complete reimplementation of the "llvmc" tool. It is
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]123designed to overcome several problems with the original llvmc and to provide a
124superset of the features of the 'gcc' driver.</p>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]125
126<p>The main features of llvmc2 is:</p>
127
128<ul>
129<li>Extended handling of command line options and smart rules for
130dispatching them to different tools.</li>
131<li>Flexible (and extensible) rules for defining different tools.</li>
132<li>The different intermediate steps performed by tools are represented
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]133as edges in the abstract graph.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]134<li>The 'language' for driver behavior definition is tablegen and thus
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]135it's relatively easy to add new features.</li>
136<li>The definition of driver is transformed into set of C++ classes, thus
137no runtime interpretation is needed.</li>
138</ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]139</li>
140
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]141
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]142<li>Reimplemented <a href="LinkTimeOptimization.html">LTO interface</a> in
143 C.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]144
145
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]146<li>Kaleidoscope tutorial in Ocaml.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]147
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]148</ul>
149
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]150</div>
151
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]152
153<!--=========================================================================-->
154<div class="doc_subsection">
155<a name="frontends">llvm-gcc 4.2 Improvements and Clang</a>
156</div>
157
158<div class="doc_text">
159
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]160<p>LLVM 2.3 fully supports the llvm-gcc 4.2 front-end.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]161
162<p>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
163front-end. Objective-C now works very well on Mac OS/X.</p>
164
165<p>llvm-gcc 4.2 includes many other fixes which improve conformance with the
166relevant parts of the GCC testsuite.</p>
167
168<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
169a set of new 'llvm native' front-end technologies for the LLVM optimizer
170and code generator. Currently, its C and Objective-C support is maturing
171nicely, and it has advanced source-to-source analysis and transformation
172capabilities. If you are interested in building source-level tools for C and
173Objective-C (and eventually C++), you should take a look. However, note that
174clang is not an official part of the LLVM 2.3 release. If you are interested in
175this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
176
177</div>
178
179
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]180<!--=========================================================================-->
181<div class="doc_subsection">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]182<a name="coreimprovements">LLVM Core Improvements</a>
183</div>
184
185<div class="doc_text">
186<p>New features include:
187</p>
188
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]189
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]190Common linkage?
191
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]192Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize",
Anton Korobeynikov877b73b2008-06-08 10:23:46 +0000[diff] [blame]193"__sync_val_compare_and_swap", etc
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]194
195<ul>
Gordon Henriksenf9b229b2008-06-05 12:51:50 +0000[diff] [blame]196<li>The C and Ocaml bindings have received additional improvements. The
197bindings now cover pass managers, several transformation passes, iteration
198over the LLVM IR, target data, and parameter attribute lists.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]199</ul>
200
201</div>
202
203<!--=========================================================================-->
204<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]205<a name="optimizer">Optimizer Improvements</a>
206</div>
207
208<div class="doc_text">
209
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]210<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]211LLVM 2.3 optimizers support a few major enhancements:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]212
213<ul>
214
Devang Patel67e46712008-06-05 21:44:00 +0000[diff] [blame]215<li>Loop index set splitting on by default.<p>
216This transformation hoists conditions from loop bodies and reduces loop's
217iteration space to improve performance. For example, <p>
218<pre>
Chris Lattnerabc3b352008-06-08 20:25:30 +0000[diff] [blame]219for (i = LB; i &lt; UB; ++i)
220 if (i &lt;= NV)
Devang Patel67e46712008-06-05 21:44:00 +0000[diff] [blame]221 LOOP_BODY
222</pre>
223is transformed into
224<pre>
225NUB = min(NV+1, UB)
Chris Lattnerabc3b352008-06-08 20:25:30 +0000[diff] [blame]226for (i = LB; i &lt; NUB; ++i)
Devang Patel67e46712008-06-05 21:44:00 +0000[diff] [blame]227 LOOP_BODY
228</pre>
229</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]230
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]231<li>LLVM includes a new <tt>memcpy</tt> optimization pass removes
232dead <tt>memcpy</tt> calls, unneeded copies of aggregates, and performs
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]233return slot optimization. The LLVM optimizer now notices long sequences of
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]234consecutive stores and merges them into <tt>memcpy</tt>'s where profitable.</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]235
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]236<li>Alignment detection for vector memory references and for <tt>memcpy</tt> and
237<tt>memset</tt> is now more aggressive.</li>
Owen Anderson7f8ea062008-06-06 16:23:15 +0000[diff] [blame]238
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]239<li>The aggressive dead code elimination (ADCE) optimization has been rewritten
240to make it both faster and safer in the presence of code containing infinite
241loops. Some of its prior functionality has been factored out into the loop
242deletion pass, which <em>is</em> safe for infinite loops.</li>
243
244<li>Several optimizations have been sped up, leading to faster code generation
245 with the same code quality.</li>
246
247<li>The 'SimplifyLibCalls' pass, which optimizes calls to libc and libm
248 functions for C-based languages, has been rewritten to be a FunctionPass
249 instead a ModulePass. This allows it to be run more often and to be
250 included at -O1 in llvm-gcc. It was also extended to include more
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]251 optimizations and several corner case bugs were fixed.</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]252
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]253<li>LLVM now includes a simple 'Jump Threading' pass, which attempts to simplify
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]254 conditional branches using information about predecessor blocks, simplifying
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]255 the control flow graph. This pass is pretty basic at this point, but
256 catches some important cases and provides a foundation to build on.</li>
257
258<li>Several corner case bugs which could lead to deleting volatile memory
259 accesses have been fixed.</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]260</ul>
261
262</div>
263
264<!--=========================================================================-->
265<div class="doc_subsection">
266<a name="codegen">Code Generator Improvements</a>
267</div>
268
269<div class="doc_text">
270
271<p>We put a significant amount of work into the code generator infrastructure,
272which allows us to implement more aggressive algorithms and make it run
273faster:</p>
274
275<ul>
276<li>MemOperand in the code generator: describe me!.</li>
277
278<li>The target-independent code generator infrastructure now uses LLVM's APInt
279 class to handle integer values, which allows it to support integer types
280 larger than 64 bits. Note that support for such types is also dependent on
281 target-specific support. Use of APInt is also a step toward support for
282 non-power-of-2 integer sizes.</li>
283
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]284<li>LLVM 2.3 includes several compile time speedups for code with large basic
285 blocks, particular in the instruction selection phase, register allocation,
286 scheduling, and tail merging/jump threading.</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]287
288<li>Several improvements which make llc's <tt>--view-sunit-dags</tt>
289 visualization of scheduling dependency graphs easier to understand.</li>
290
291<li>The code generator allows targets to write patterns that generate subreg
292 references directly in .td files now.</li>
293
294<li><tt>memcpy</tt> lowering in the backend is more aggressive, particularly for
295 <tt>memcpy</tt> calls introduced by the code generator when handling
296 pass-by-value structure argument copies.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]297
298<li>Inline assembly with multiple register results now returns those results
299 directly in the appropriate registers, rather than going through memory.
300 Inline assembly that uses constraints like "ir" with immediates now use the
301 'i' form when possible instead of always loading the value in a register.
302 This saves an instruction and reduces register use.</li>
303
304<li>Added support for PIC/GOT style tail calls on x86/32 and initial support
305 for tail calls on PowerPC 32 (it may also work on ppc64 but not
306 thoroughly tested).</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]307</ul>
308
309</div>
310
311
312<!--=========================================================================-->
313<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]314<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]315</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]316
317<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]318<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319</p>
320
321<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]322<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]323 area of passing and returning structures by value. llvm-gcc compiled code
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]324 now interoperates very well on X86-64 systems with other compilers.</li>
325
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]326<li>Support for Win64 was added. This includes code generation itself, JIT
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]327 support and necessary changes to llvm-gcc.</li>
328
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]329<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]330 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins. Various
331 generic vector operations (insert/extract/shuffle) are much more efficient
332 when SSE 4.1 is enabled. The JIT automatically takes advantage of these
333 instructions, but llvm-gcc must be explicitly told to use them, e.g. with
334 <tt>-march=penryn</tt>.</li>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]335
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]336<li>The X86 backend now does a number of optimizations that aim to avoid
337 converting numbers back and forth from SSE registers to the X87 floating
338 point stack.</li>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]339
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]340<li>The X86 backend supports stack realignment, which is particularly useful for
341 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]342
343<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
344 functions to be tagged as passing floating point values in SSE
345 registers.</li>
346
347<li>Trampolines (taking the address of a nested function) now work on
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]348 Linux/X86-64.</li>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]349
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]350<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
351 instructions instead of being ignored.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]352
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]353<li>128-bit integers are now supported on X86-64 targets.</li>
Dan Gohman74e1ff52008-06-05 16:15:39 +0000[diff] [blame]354
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]355<li>The register allocator can now rematerialize PIC-base computations.</li>
356
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]357<li>The "t" and "f" inline assembly constraints for the X87 floating point stack
358 now work. However, the "u" constraint is still not fully supported.</li>
359
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]360</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]361
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]362</div>
363
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]364<!--=========================================================================-->
365<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]366<a name="targetspecific">Other Target Specific Improvements</a>
367</div>
368
369<div class="doc_text">
370<p>New target-specific features include:
371</p>
372
373<ul>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]374<li>The LLVM C backend now supports vector code.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]375</ul>
376
377</div>
378
379
380
381<!--=========================================================================-->
382<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]383<a name="otherimprovements">Other Improvements</a>
384</div>
385
386<div class="doc_text">
387<p>New features include:
388</p>
389
390<ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]391<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]392<li>Bugpoint now supports running custom scripts (with the <tt>-run-custom</tt>
393 option) to determine how to execute the command and whether it is making
394 forward process.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]395</ul>
396
397</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]398
399<!-- *********************************************************************** -->
400<div class="doc_section">
401 <a name="portability">Portability and Supported Platforms</a>
402</div>
403<!-- *********************************************************************** -->
404
405<div class="doc_text">
406
407<p>LLVM is known to work on the following platforms:</p>
408
409<ul>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]410<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]411 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]412<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]413 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]414<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]415<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
416 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]417<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]418<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]419<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]420</ul>
421
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]422<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]423to the machine and operating system on which it is built. However, minor
424porting may be required to get LLVM to work on new platforms. We welcome your
425portability patches and reports of successful builds or error messages.</p>
426
427</div>
428
429<!-- *********************************************************************** -->
430<div class="doc_section">
431 <a name="knownproblems">Known Problems</a>
432</div>
433<!-- *********************************************************************** -->
434
435<div class="doc_text">
436
437<p>This section contains all known problems with the LLVM system, listed by
438component. As new problems are discovered, they will be added to these
439sections. If you run into a problem, please check the <a
440href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
441there isn't already one.</p>
442
443</div>
444
445<!-- ======================================================================= -->
446<div class="doc_subsection">
447 <a name="experimental">Experimental features included with this release</a>
448</div>
449
450<div class="doc_text">
451
452<p>The following components of this LLVM release are either untested, known to
453be broken or unreliable, or are in early development. These components should
454not be relied on, and bugs should not be filed against them, but they may be
455useful to some people. In particular, if you would like to work on one of these
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]456components, please contact us on the <a
457href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]458
459<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]460<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]461<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]462 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]463</ul>
464
465</div>
466
467<!-- ======================================================================= -->
468<div class="doc_subsection">
469 <a name="x86-be">Known problems with the X86 back-end</a>
470</div>
471
472<div class="doc_text">
473
474<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]475 <li>The X86 backend does not yet support
476 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
477 floating point stack</a>. It supports the 'f' and 't' constraints, but not
478 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]479 <li>The X86 backend generates inefficient floating point code when configured
480 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]481 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]482 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
483 currently due
484 to <a href="http://llvm.org/PR2255">several</a>
485 <a href="http://llvm.org/PR2257">bugs</a> in FP stackifier
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]486</ul>
487
488</div>
489
490<!-- ======================================================================= -->
491<div class="doc_subsection">
492 <a name="ppc-be">Known problems with the PowerPC back-end</a>
493</div>
494
495<div class="doc_text">
496
497<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]498<li>The Linux PPC32/ABI support needs testing for the interpreter and static
499compilation, and lacks support for debug information.</li>
500</ul>
501
502</div>
503
504<!-- ======================================================================= -->
505<div class="doc_subsection">
506 <a name="arm-be">Known problems with the ARM back-end</a>
507</div>
508
509<div class="doc_text">
510
511<ul>
512<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]513processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]514results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
515<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
516</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]517<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
518 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]519programs compiled with LLVM. Please use more recent versions of QEMU.</li>
520</ul>
521
522</div>
523
524<!-- ======================================================================= -->
525<div class="doc_subsection">
526 <a name="sparc-be">Known problems with the SPARC back-end</a>
527</div>
528
529<div class="doc_text">
530
531<ul>
532<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
533 support the 64-bit SPARC ABI (-m64).</li>
534</ul>
535
536</div>
537
538<!-- ======================================================================= -->
539<div class="doc_subsection">
540 <a name="alpha-be">Known problems with the Alpha back-end</a>
541</div>
542
543<div class="doc_text">
544
545<ul>
546
547<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
548appropriate nops inserted to ensure restartability.</li>
549
550</ul>
551</div>
552
553<!-- ======================================================================= -->
554<div class="doc_subsection">
555 <a name="ia64-be">Known problems with the IA64 back-end</a>
556</div>
557
558<div class="doc_text">
559
560<ul>
561
562<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
563made where the argument is not 16-byte aligned, as required on IA64. (Strictly
564speaking this is not a bug in the IA64 back-end; it will also be encountered
565when building C++ programs using the C back-end.)</li>
566
567<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
568ABI compliant layout of v-tables</a>. In particular, it just stores function
569pointers instead of function descriptors in the vtable. This bug prevents
570mixing C++ code compiled with LLVM with C++ objects compiled by other C++
571compilers.</li>
572
573<li>There are a few ABI violations which will lead to problems when mixing LLVM
574output with code built with other compilers, particularly for floating-point
575programs.</li>
576
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]577<li>Defining vararg functions is not supported (but calling them is OK).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]578
579<li>The Itanium backend has bitrotted somewhat.</li>
580</ul>
581
582</div>
583
584<!-- ======================================================================= -->
585<div class="doc_subsection">
586 <a name="c-be">Known problems with the C back-end</a>
587</div>
588
589<div class="doc_text">
590
591<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]592<li><a href="http://llvm.org/PR802">The C backend has only basic support for
593 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]594<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
595 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]596 C++ code compiled with llc or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]597<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]598</ul>
599
600</div>
601
602
603<!-- ======================================================================= -->
604<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]605 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]606</div>
607
608<!-- _______________________________________________________________________ -->
609<div class="doc_subsubsection">Bugs</div>
610
611<div class="doc_text">
612
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]613<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
614Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]615llvmdev mailing list if you are interested.</p>
616
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]617<p>The only major language feature of GCC not supported by llvm-gcc is
618 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
619 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]620 supported on some targets (these are used when you take the address of a
621 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]622
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]623<p>If you run into GCC extensions which are not supported, please let us know.
624</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]625
626</div>
627
628<!-- ======================================================================= -->
629<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]630 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]631</div>
632
633<div class="doc_text">
634
635<p>The C++ front-end is considered to be fully
636tested and works for a number of non-trivial programs, including LLVM
637itself, Qt, Mozilla, etc.</p>
638
639<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]640<li>Exception handling works well on the X86 and PowerPC targets, including
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]641X86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
642supported on X86-64 linux, but that is disabled by default in this release.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]643</ul>
644
645</div>
646
647
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]648<!-- ======================================================================= -->
649<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]650 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]651</div>
652
653<div class="doc_text">
654The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
655technology and problems should be expected.
656<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]657<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]658to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]659however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]660which does support trampolines.</li>
661<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
662Workaround: configure with --disable-bootstrap.</li>
663<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]664fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
665<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
666<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
667reports most tests as having failed even though they pass.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]668<li>The -E binder option (exception backtraces)
669<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
670crashing if an exception is raised. Workaround: do not use -E.</li>
671<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
672or finish at a non-byte offset</a> in a record. Workaround: do not pack records
673or use representation clauses that result in a field of a non-discrete type
674starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame^]675<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
676'main' as generated by the Ada binder to be invalid</a>.
677Workaround: hand edit the file to use pointers for <tt>argv</tt> and
678<tt>envp</tt> rather than integers.</li>
679<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
680ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]681</ul>
682</div>
683
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]684<!-- *********************************************************************** -->
685<div class="doc_section">
686 <a name="additionalinfo">Additional Information</a>
687</div>
688<!-- *********************************************************************** -->
689
690<div class="doc_text">
691
692<p>A wide variety of additional information is available on the <a
693href="http://llvm.org">LLVM web page</a>, in particular in the <a
694href="http://llvm.org/docs/">documentation</a> section. The web page also
695contains versions of the API documentation which is up-to-date with the
696Subversion version of the source code.
697You can access versions of these documents specific to this release by going
698into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
699
700<p>If you have any questions or comments about LLVM, please feel free to contact
701us via the <a href="http://llvm.org/docs/#maillist"> mailing
702lists</a>.</p>
703
704</div>
705
706<!-- *********************************************************************** -->
707
708<hr>
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