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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>
Gordon Henriksenad095792008-06-05 12:48:32 +0000[diff] [blame^]218<li>The C and Ocaml bindings have received additional improvements. The
219bindings now cover pass managers, several transformation passes, iteration
220over the LLVM IR, target data, and parameter attribute lists.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]221</ul>
222
223</div>
224
225
226<!--=========================================================================-->
227<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]228<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]229</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]230
231<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]232<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]233</p>
234
235<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]236<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
237 area of passing and returning structures by value. llvm-gcc Compiled code
238 now interoperates very well on X86-64 systems with other compilers.</li>
239
240<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
241 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins.</li>
242
243<li>The X86 backend now does a number of optimizations that aim to avoid
244 converting numbers back and forth from SSE registers to the X87 floating
245 point stack.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]246
247<li>The X86 backend supports stack realignment, which is particularly useful for
248 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]249
250<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
251 functions to be tagged as passing floating point values in SSE
252 registers.</li>
253
254<li>Trampolines (taking the address of a nested function) now work on
255 Linux/x86-64.</li>
256
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]257<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
258 instructions instead of being ignored.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]259
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]260</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]261
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]262</div>
263
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]264<!--=========================================================================-->
265<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]266<a name="targetspecific">Other Target Specific Improvements</a>
267</div>
268
269<div class="doc_text">
270<p>New target-specific features include:
271</p>
272
273<ul>
274<li>The LLVM C backend now supports vectors code.</li>
275
276
277</ul>
278
279</div>
280
281
282
283<!--=========================================================================-->
284<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]285<a name="otherimprovements">Other Improvements</a>
286</div>
287
288<div class="doc_text">
289<p>New features include:
290</p>
291
292<ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]293<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]294<li>llvm2cpp tool was moved into llc, use llc -march=cpp</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]295</ul>
296
297</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]298
299<!-- *********************************************************************** -->
300<div class="doc_section">
301 <a name="portability">Portability and Supported Platforms</a>
302</div>
303<!-- *********************************************************************** -->
304
305<div class="doc_text">
306
307<p>LLVM is known to work on the following platforms:</p>
308
309<ul>
310<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
311 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]312<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]313 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]314<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]315<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
316 support is available for native builds with Visual C++).</li>
317<li>Sun UltraSPARC workstations running Solaris 8.</li>
318<li>Alpha-based machines running Debian GNU/Linux.</li>
319<li>Itanium-based machines running Linux and HP-UX.</li>
320</ul>
321
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]322<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]323to the machine and operating system on which it is built. However, minor
324porting may be required to get LLVM to work on new platforms. We welcome your
325portability patches and reports of successful builds or error messages.</p>
326
327</div>
328
329<!-- *********************************************************************** -->
330<div class="doc_section">
331 <a name="knownproblems">Known Problems</a>
332</div>
333<!-- *********************************************************************** -->
334
335<div class="doc_text">
336
337<p>This section contains all known problems with the LLVM system, listed by
338component. As new problems are discovered, they will be added to these
339sections. If you run into a problem, please check the <a
340href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
341there isn't already one.</p>
342
343</div>
344
345<!-- ======================================================================= -->
346<div class="doc_subsection">
347 <a name="experimental">Experimental features included with this release</a>
348</div>
349
350<div class="doc_text">
351
352<p>The following components of this LLVM release are either untested, known to
353be broken or unreliable, or are in early development. These components should
354not be relied on, and bugs should not be filed against them, but they may be
355useful 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]356components, please contact us on the <a
357href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]358
359<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]360<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]361<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
362 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]363</ul>
364
365</div>
366
367<!-- ======================================================================= -->
368<div class="doc_subsection">
369 <a name="x86-be">Known problems with the X86 back-end</a>
370</div>
371
372<div class="doc_text">
373
374<ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]375<li>The X86 backend does not yet support all <a
376 href="http://llvm.org/PR879">inline assembly that uses the X86 floating
377 point stack</a>. It supports the 'f' and 't' constraints, but not 'u'.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]378<li>The X86 backend generates inefficient floating point code when configured to
379 generate code for systems that don't have SSE2.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]380</ul>
381
382</div>
383
384<!-- ======================================================================= -->
385<div class="doc_subsection">
386 <a name="ppc-be">Known problems with the PowerPC back-end</a>
387</div>
388
389<div class="doc_text">
390
391<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]392<li>The Linux PPC32/ABI support needs testing for the interpreter and static
393compilation, and lacks support for debug information.</li>
394</ul>
395
396</div>
397
398<!-- ======================================================================= -->
399<div class="doc_subsection">
400 <a name="arm-be">Known problems with the ARM back-end</a>
401</div>
402
403<div class="doc_text">
404
405<ul>
406<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]407processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]408results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
409<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
410</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]411<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]412programs compiled with LLVM. Please use more recent versions of QEMU.</li>
413</ul>
414
415</div>
416
417<!-- ======================================================================= -->
418<div class="doc_subsection">
419 <a name="sparc-be">Known problems with the SPARC back-end</a>
420</div>
421
422<div class="doc_text">
423
424<ul>
425<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
426 support the 64-bit SPARC ABI (-m64).</li>
427</ul>
428
429</div>
430
431<!-- ======================================================================= -->
432<div class="doc_subsection">
433 <a name="alpha-be">Known problems with the Alpha back-end</a>
434</div>
435
436<div class="doc_text">
437
438<ul>
439
440<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
441appropriate nops inserted to ensure restartability.</li>
442
443</ul>
444</div>
445
446<!-- ======================================================================= -->
447<div class="doc_subsection">
448 <a name="ia64-be">Known problems with the IA64 back-end</a>
449</div>
450
451<div class="doc_text">
452
453<ul>
454
455<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
456made where the argument is not 16-byte aligned, as required on IA64. (Strictly
457speaking this is not a bug in the IA64 back-end; it will also be encountered
458when building C++ programs using the C back-end.)</li>
459
460<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
461ABI compliant layout of v-tables</a>. In particular, it just stores function
462pointers instead of function descriptors in the vtable. This bug prevents
463mixing C++ code compiled with LLVM with C++ objects compiled by other C++
464compilers.</li>
465
466<li>There are a few ABI violations which will lead to problems when mixing LLVM
467output with code built with other compilers, particularly for floating-point
468programs.</li>
469
470<li>Defining vararg functions is not supported (but calling them is ok).</li>
471
472<li>The Itanium backend has bitrotted somewhat.</li>
473</ul>
474
475</div>
476
477<!-- ======================================================================= -->
478<div class="doc_subsection">
479 <a name="c-be">Known problems with the C back-end</a>
480</div>
481
482<div class="doc_text">
483
484<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]485<li><a href="http://llvm.org/PR802">The C backend has only basic support for
486 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]487<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
488 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
489 C++ code compiled with LLC or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]490<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]491</ul>
492
493</div>
494
495
496<!-- ======================================================================= -->
497<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]498 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]499</div>
500
501<!-- _______________________________________________________________________ -->
502<div class="doc_subsubsection">Bugs</div>
503
504<div class="doc_text">
505
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]506<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
507Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]508llvmdev mailing list if you are interested.</p>
509
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]510<p>The only major language feature of GCC not supported by llvm-gcc is
511 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
512 are only supported on some targets. For example, trampolines are only
513 supported on some targets, which are used when you take the address of a
514 nested function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]515
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]516<p>If you run into GCC extensions which are not supported, please let us know.
517</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]518
519</div>
520
521<!-- ======================================================================= -->
522<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]523 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]524</div>
525
526<div class="doc_text">
527
528<p>The C++ front-end is considered to be fully
529tested and works for a number of non-trivial programs, including LLVM
530itself, Qt, Mozilla, etc.</p>
531
532<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]533<li>Exception handling works well on the X86 and PowerPC targets, including
534x86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
535supported on x86-64 linux, but that is disabled by default in this release.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]536</ul>
537
538</div>
539
540
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]541<!-- ======================================================================= -->
542<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]543 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]544</div>
545
546<div class="doc_text">
547The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
548technology and problems should be expected.
549<ul>
550<li>The Ada front-end currently only builds on x86-32. This is mainly due
551to lack of trampoline support (pointers to nested functions) on other platforms,
552however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
553which does support trampolines.</li>
554<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
555Workaround: configure with --disable-bootstrap.</li>
556<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
557fail (c380004 also fails with gcc-4.2 mainline).</li>
558<li>Many gcc specific Ada tests continue to crash the compiler.</li>
559<li>The -E binder option (exception backtraces)
560<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
561crashing if an exception is raised. Workaround: do not use -E.</li>
562<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
563or finish at a non-byte offset</a> in a record. Workaround: do not pack records
564or use representation clauses that result in a field of a non-discrete type
565starting or finishing in the middle of a byte.</li>
566<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
567as generated by the Ada binder to be invalid</a>.
568Workaround: hand edit the file to use pointers for argv and envp rather than
569integers.</li>
570<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
571</ul>
572</div>
573
574<!-- ======================================================================= -->
575<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]576 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]577</div>
578
579<div class="doc_text">
580
581<ul>
582<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
583<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
584</ul>
585</div>
586
587
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]588
589<!-- *********************************************************************** -->
590<div class="doc_section">
591 <a name="additionalinfo">Additional Information</a>
592</div>
593<!-- *********************************************************************** -->
594
595<div class="doc_text">
596
597<p>A wide variety of additional information is available on the <a
598href="http://llvm.org">LLVM web page</a>, in particular in the <a
599href="http://llvm.org/docs/">documentation</a> section. The web page also
600contains versions of the API documentation which is up-to-date with the
601Subversion version of the source code.
602You can access versions of these documents specific to this release by going
603into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
604
605<p>If you have any questions or comments about LLVM, please feel free to contact
606us via the <a href="http://llvm.org/docs/#maillist"> mailing
607lists</a>.</p>
608
609</div>
610
611<!-- *********************************************************************** -->
612
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