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Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]7 <title>LLVM 2.3 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]11<div class="doc_title">LLVM 2.3 Release Notes</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]12
13<ol>
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
17 <li><a href="#portability">Portability and Supported Platforms</a></li>
18 <li><a href="#knownproblems">Known Problems</a>
19 <li><a href="#additionalinfo">Additional Information</a></li>
20</ol>
21
22<div class="doc_author">
23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
24</div>
25
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]26<!-- Done through Week-of-Mon-20080324.txt -->
27
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]28<!-- *********************************************************************** -->
29<div class="doc_section">
30 <a name="intro">Introduction</a>
31</div>
32<!-- *********************************************************************** -->
33
34<div class="doc_text">
35
36<p>This document contains the release notes for the LLVM compiler
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]37infrastructure, release 2.3. Here we describe the status of LLVM, including
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]38major improvements from the previous release and any known problems. All LLVM
39releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
40releases web site</a>.</p>
41
42<p>For more information about LLVM, including information about the latest
43release, please check out the <a href="http://llvm.org/">main LLVM
44web site</a>. If you have questions or comments, the <a
45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
46list</a> is a good place to send them.</p>
47
48<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]49main LLVM web page, this document applies to the <i>next</i> release, not the
50current one. To see the release notes for a specific releases, please see the
51<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]52
53</div>
54
55<!-- *********************************************************************** -->
56<div class="doc_section">
57 <a name="whatsnew">What's New?</a>
58</div>
59<!-- *********************************************************************** -->
60
61<div class="doc_text">
62
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]63<p>This is the fourteenth public release of the LLVM Compiler Infrastructure.
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]64It includes a large number of features and refinements from LLVM 2.2.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]65
66</div>
67
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]68<!-- Unfinished features in 2.3:
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]69 Machine LICM
70 Machine Sinking
71 LegalizeDAGTypes
72 -->
73
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]74<!--=========================================================================-->
75<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]76<a name="changes">Major Changes in LLVM 2.3</a>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]77</div>
78
79<div class="doc_text">
80
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]81<p>LLVM 2.2 was the last LLVM release to support llvm-gcc 4.0 and llvm-upgrade.
82llvm-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]83upgrading LLVM 1.9 files to LLVM 2.x syntax, but you can always use a previous
84LLVM release to do this. One nice impact of this is that the LLVM regressionn
85test suite no longer depends on llvm-upgrade, which makes it run faster.</p>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]86
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]87<p>LLVM 2.3 renames the LLVMBuilder and LLVMFoldingBuilder classes to
88 IRBuilder.</p>
89
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]90</div>
91
92<!--=========================================================================-->
93<div class="doc_subsection">
94<a name="majorfeatures">Major New Features</a>
95</div>
96
97<div class="doc_text">
98
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]99<p>LLVM 2.3 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]100
101<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]102<li>Multiple Return Value Support</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]103
104
105<li><p>LLVM 2.3 includes a complete reimplementation of the "llvmc" tool. It is
106designed to overcome several problems of the original llvmc and to provide a
107superset of the features as the 'gcc' driver.</p>
108
109<p>The main features of llvmc2 is:</p>
110
111<ul>
112<li>Extended handling of command line options and smart rules for
113dispatching them to different tools.</li>
114<li>Flexible (and extensible) rules for defining different tools.</li>
115<li>The different intermediate steps performed by tools are represented
116as edged in the abstract graph.</li>
117</l>The 'language' for driver behaviour definition is tablegen and thus
118it's relatively easy to add new features.</li>
119<li>The definition of driver is transformed into set of C++ classes, thus
120no runtime interpretation is needed.</li>
121</ul>
122
123</li>
124
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]125<li>Reimplemented <a href="LinkTimeOptimization.html">LTO interface</a> in
126 C.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]127
128
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]129<li>kaleidoscope tutorial in ocaml.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]130
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]131</ul>
132
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]133</div>
134
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]135
136<!--=========================================================================-->
137<div class="doc_subsection">
138<a name="frontends">llvm-gcc 4.2 Improvements and Clang</a>
139</div>
140
141<div class="doc_text">
142
143<p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end.</p>
144
145<p>llvm-gcc 4.2 includes numerous fixes to better support the Objective-C
146front-end. Objective-C now works very well on Mac OS/X.</p>
147
148<p>llvm-gcc 4.2 includes many other fixes which improve conformance with the
149relevant parts of the GCC testsuite.</p>
150
151<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
152a set of new 'llvm native' front-end technologies for the LLVM optimizer
153and code generator. Currently, its C and Objective-C support is maturing
154nicely, and it has advanced source-to-source analysis and transformation
155capabilities. If you are interested in building source-level tools for C and
156Objective-C (and eventually C++), you should take a look. However, note that
157clang is not an official part of the LLVM 2.3 release. If you are interested in
158this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
159
160</div>
161
162
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]163<!--=========================================================================-->
164<div class="doc_subsection">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]165<a name="coreimprovements">LLVM Core Improvements</a>
166</div>
167
168<div class="doc_text">
169<p>New features include:
170</p>
171
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]172
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]173Common linkage?
174
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]175Atomic operation support, Alpha, X86, X86-64, PowerPC. "__sync_synchronize"
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]176
177<ul>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]178</ul>
179
180</div>
181
182<!--=========================================================================-->
183<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]184<a name="codegen">Code Generator Improvements</a>
185</div>
186
187<div class="doc_text">
188
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]189<p>We put a significant amount of work into the code generator infrastructure,
190which allows us to implement more aggressive algorithms and make it run
191faster:</p>
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]192
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]193<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]194<li>MemOperand in the code generator: describe me!.</li>
195<li>i128 support and APInt through most of codegen.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]196<li>Several compile time speedups for code with large basic blocks.</li>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]197</ul>
198
199</div>
200
201<!--=========================================================================-->
202<div class="doc_subsection">
203<a name="optimizer">Optimizer Improvements</a>
204</div>
205
206<div class="doc_text">
207
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]208<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]209LLVM 2.3 optimizers support a few major enhancements:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]210
211<ul>
212
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]213<li>Loop index set splitting on by default: describe me.</li>
214<li>LLVM includes a new memcpy optimization pass which optimizes out dead
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]215memcpy calls, unneeded copies of aggregates, and handles the return slot
216optimization. The LLVM optimizer now notices long sequences of consequtive
217stores and merges them into memcpy's where profitable.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]218</ul>
219
220</div>
221
222
223<!--=========================================================================-->
224<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]225<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]226</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]227
228<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]229<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]230</p>
231
232<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]233<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
234 area of passing and returning structures by value. llvm-gcc Compiled code
235 now interoperates very well on X86-64 systems with other compilers.</li>
236
237<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
238 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins.</li>
239
240<li>The X86 backend now does a number of optimizations that aim to avoid
241 converting numbers back and forth from SSE registers to the X87 floating
242 point stack.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]243
244<li>The X86 backend supports stack realignment, which is particularly useful for
245 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]246
247<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
248 functions to be tagged as passing floating point values in SSE
249 registers.</li>
250
251<li>Trampolines (taking the address of a nested function) now work on
252 Linux/x86-64.</li>
253
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]254<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
255 instructions instead of being ignored.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]256
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]257</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]258
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]259</div>
260
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]261<!--=========================================================================-->
262<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]263<a name="targetspecific">Other Target Specific Improvements</a>
264</div>
265
266<div class="doc_text">
267<p>New target-specific features include:
268</p>
269
270<ul>
271<li>The LLVM C backend now supports vectors code.</li>
272
273
274</ul>
275
276</div>
277
278
279
280<!--=========================================================================-->
281<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]282<a name="otherimprovements">Other Improvements</a>
283</div>
284
285<div class="doc_text">
286<p>New features include:
287</p>
288
289<ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]290<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]291<li>llvm2cpp tool was moved into llc, use llc -march=cpp</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]292</ul>
293
294</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]295
296<!-- *********************************************************************** -->
297<div class="doc_section">
298 <a name="portability">Portability and Supported Platforms</a>
299</div>
300<!-- *********************************************************************** -->
301
302<div class="doc_text">
303
304<p>LLVM is known to work on the following platforms:</p>
305
306<ul>
307<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
308 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]309<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]310 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]311<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]312<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
313 support is available for native builds with Visual C++).</li>
314<li>Sun UltraSPARC workstations running Solaris 8.</li>
315<li>Alpha-based machines running Debian GNU/Linux.</li>
316<li>Itanium-based machines running Linux and HP-UX.</li>
317</ul>
318
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]319<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]320to the machine and operating system on which it is built. However, minor
321porting may be required to get LLVM to work on new platforms. We welcome your
322portability patches and reports of successful builds or error messages.</p>
323
324</div>
325
326<!-- *********************************************************************** -->
327<div class="doc_section">
328 <a name="knownproblems">Known Problems</a>
329</div>
330<!-- *********************************************************************** -->
331
332<div class="doc_text">
333
334<p>This section contains all known problems with the LLVM system, listed by
335component. As new problems are discovered, they will be added to these
336sections. If you run into a problem, please check the <a
337href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
338there isn't already one.</p>
339
340</div>
341
342<!-- ======================================================================= -->
343<div class="doc_subsection">
344 <a name="experimental">Experimental features included with this release</a>
345</div>
346
347<div class="doc_text">
348
349<p>The following components of this LLVM release are either untested, known to
350be broken or unreliable, or are in early development. These components should
351not be relied on, and bugs should not be filed against them, but they may be
352useful 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]353components, please contact us on the <a
354href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]355
356<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]357<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]358<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
359 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]360</ul>
361
362</div>
363
364<!-- ======================================================================= -->
365<div class="doc_subsection">
366 <a name="x86-be">Known problems with the X86 back-end</a>
367</div>
368
369<div class="doc_text">
370
371<ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame^]372<li>The X86 backend does not yet support all <a
373 href="http://llvm.org/PR879">inline assembly that uses the X86 floating
374 point stack</a>. It supports the 'f' and 't' constraints, but not 'u'.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]375<li>The X86 backend generates inefficient floating point code when configured to
376 generate code for systems that don't have SSE2.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]377</ul>
378
379</div>
380
381<!-- ======================================================================= -->
382<div class="doc_subsection">
383 <a name="ppc-be">Known problems with the PowerPC back-end</a>
384</div>
385
386<div class="doc_text">
387
388<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]389<li>The Linux PPC32/ABI support needs testing for the interpreter and static
390compilation, and lacks support for debug information.</li>
391</ul>
392
393</div>
394
395<!-- ======================================================================= -->
396<div class="doc_subsection">
397 <a name="arm-be">Known problems with the ARM back-end</a>
398</div>
399
400<div class="doc_text">
401
402<ul>
403<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]404processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]405results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
406<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
407</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]408<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]409programs compiled with LLVM. Please use more recent versions of QEMU.</li>
410</ul>
411
412</div>
413
414<!-- ======================================================================= -->
415<div class="doc_subsection">
416 <a name="sparc-be">Known problems with the SPARC back-end</a>
417</div>
418
419<div class="doc_text">
420
421<ul>
422<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
423 support the 64-bit SPARC ABI (-m64).</li>
424</ul>
425
426</div>
427
428<!-- ======================================================================= -->
429<div class="doc_subsection">
430 <a name="alpha-be">Known problems with the Alpha back-end</a>
431</div>
432
433<div class="doc_text">
434
435<ul>
436
437<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
438appropriate nops inserted to ensure restartability.</li>
439
440</ul>
441</div>
442
443<!-- ======================================================================= -->
444<div class="doc_subsection">
445 <a name="ia64-be">Known problems with the IA64 back-end</a>
446</div>
447
448<div class="doc_text">
449
450<ul>
451
452<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
453made where the argument is not 16-byte aligned, as required on IA64. (Strictly
454speaking this is not a bug in the IA64 back-end; it will also be encountered
455when building C++ programs using the C back-end.)</li>
456
457<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
458ABI compliant layout of v-tables</a>. In particular, it just stores function
459pointers instead of function descriptors in the vtable. This bug prevents
460mixing C++ code compiled with LLVM with C++ objects compiled by other C++
461compilers.</li>
462
463<li>There are a few ABI violations which will lead to problems when mixing LLVM
464output with code built with other compilers, particularly for floating-point
465programs.</li>
466
467<li>Defining vararg functions is not supported (but calling them is ok).</li>
468
469<li>The Itanium backend has bitrotted somewhat.</li>
470</ul>
471
472</div>
473
474<!-- ======================================================================= -->
475<div class="doc_subsection">
476 <a name="c-be">Known problems with the C back-end</a>
477</div>
478
479<div class="doc_text">
480
481<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]482<li><a href="http://llvm.org/PR802">The C backend has only basic support for
483 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]484<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
485 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
486 C++ code compiled with LLC or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]487<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]488</ul>
489
490</div>
491
492
493<!-- ======================================================================= -->
494<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]495 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]496</div>
497
498<!-- _______________________________________________________________________ -->
499<div class="doc_subsubsection">Bugs</div>
500
501<div class="doc_text">
502
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]503<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
504Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]505llvmdev mailing list if you are interested.</p>
506
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]507<p>The only major language feature of GCC not supported by llvm-gcc is
508 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
509 are only supported on some targets. For example, trampolines are only
510 supported on some targets, which are used when you take the address of a
511 nested function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]512
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]513<p>If you run into GCC extensions which are not supported, please let us know.
514</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]515
516</div>
517
518<!-- ======================================================================= -->
519<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]520 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]521</div>
522
523<div class="doc_text">
524
525<p>The C++ front-end is considered to be fully
526tested and works for a number of non-trivial programs, including LLVM
527itself, Qt, Mozilla, etc.</p>
528
529<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]530<li>Exception handling works well on the X86 and PowerPC targets, including
531x86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
532supported on x86-64 linux, but that is disabled by default in this release.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]533</ul>
534
535</div>
536
537
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]538<!-- ======================================================================= -->
539<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]540 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]541</div>
542
543<div class="doc_text">
544The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
545technology and problems should be expected.
546<ul>
547<li>The Ada front-end currently only builds on x86-32. This is mainly due
548to lack of trampoline support (pointers to nested functions) on other platforms,
549however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
550which does support trampolines.</li>
551<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
552Workaround: configure with --disable-bootstrap.</li>
553<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
554fail (c380004 also fails with gcc-4.2 mainline).</li>
555<li>Many gcc specific Ada tests continue to crash the compiler.</li>
556<li>The -E binder option (exception backtraces)
557<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
558crashing if an exception is raised. Workaround: do not use -E.</li>
559<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
560or finish at a non-byte offset</a> in a record. Workaround: do not pack records
561or use representation clauses that result in a field of a non-discrete type
562starting or finishing in the middle of a byte.</li>
563<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
564as generated by the Ada binder to be invalid</a>.
565Workaround: hand edit the file to use pointers for argv and envp rather than
566integers.</li>
567<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
568</ul>
569</div>
570
571<!-- ======================================================================= -->
572<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]573 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]574</div>
575
576<div class="doc_text">
577
578<ul>
579<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
580<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
581</ul>
582</div>
583
584
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]585
586<!-- *********************************************************************** -->
587<div class="doc_section">
588 <a name="additionalinfo">Additional Information</a>
589</div>
590<!-- *********************************************************************** -->
591
592<div class="doc_text">
593
594<p>A wide variety of additional information is available on the <a
595href="http://llvm.org">LLVM web page</a>, in particular in the <a
596href="http://llvm.org/docs/">documentation</a> section. The web page also
597contains versions of the API documentation which is up-to-date with the
598Subversion version of the source code.
599You can access versions of these documents specific to this release by going
600into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
601
602<p>If you have any questions or comments about LLVM, please feel free to contact
603us via the <a href="http://llvm.org/docs/#maillist"> mailing
604lists</a>.</p>
605
606</div>
607
608<!-- *********************************************************************** -->
609
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