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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / e858204b646b75ed8aee086b3d185c9d8ada9ef8 / . / docs / ReleaseNotes.html
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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>
Gordon Henriksenf9b229b2008-06-05 12:51:50 +0000[diff] [blame]178<li>The C and Ocaml bindings have received additional improvements. The
179bindings now cover pass managers, several transformation passes, iteration
180over the LLVM IR, target data, and parameter attribute lists.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]181</ul>
182
183</div>
184
185<!--=========================================================================-->
186<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]187<a name="codegen">Code Generator Improvements</a>
188</div>
189
190<div class="doc_text">
191
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]192<p>We put a significant amount of work into the code generator infrastructure,
193which allows us to implement more aggressive algorithms and make it run
194faster:</p>
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]195
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]196<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]197<li>MemOperand in the code generator: describe me!.</li>
Dan Gohman7e661062008-06-05 15:43:11 +0000[diff] [blame]198<li>Target-independent codegen infastructure now uses LLVM's APInt class for
199 handling integer values, which allow it to support integer types larger
200 than 64 bits. Note that support for such types is also dependent on
201 target-specific support. Use of APInt is also a step toward support for
202 non-power-of-2 integer sizes.</li>
203<li>Support for 128-bit integers on X86-64.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]204<li>Several compile time speedups for code with large basic blocks.</li>
Dan Gohmane8582042008-06-05 15:46:36 +0000[diff] [blame^]205<li>Several improvements which make llc's <tt>--view-sunit-dags</tt>
206 visualization of scheduling dependency graphs easier to understand.</li>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]207</ul>
208
209</div>
210
211<!--=========================================================================-->
212<div class="doc_subsection">
213<a name="optimizer">Optimizer Improvements</a>
214</div>
215
216<div class="doc_text">
217
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]218<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]219LLVM 2.3 optimizers support a few major enhancements:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]220
221<ul>
222
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]223<li>Loop index set splitting on by default: describe me.</li>
224<li>LLVM includes a new memcpy optimization pass which optimizes out dead
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]225memcpy calls, unneeded copies of aggregates, and handles the return slot
226optimization. The LLVM optimizer now notices long sequences of consequtive
227stores and merges them into memcpy's where profitable.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]228</ul>
229
230</div>
231
232
233<!--=========================================================================-->
234<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]235<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]236</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]237
238<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]239<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]240</p>
241
242<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]243<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
244 area of passing and returning structures by value. llvm-gcc Compiled code
245 now interoperates very well on X86-64 systems with other compilers.</li>
246
247<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
248 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins.</li>
249
250<li>The X86 backend now does a number of optimizations that aim to avoid
251 converting numbers back and forth from SSE registers to the X87 floating
252 point stack.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]253
254<li>The X86 backend supports stack realignment, which is particularly useful for
255 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]256
257<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
258 functions to be tagged as passing floating point values in SSE
259 registers.</li>
260
261<li>Trampolines (taking the address of a nested function) now work on
262 Linux/x86-64.</li>
263
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]264<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
265 instructions instead of being ignored.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]266
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]267</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]268
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]269</div>
270
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]271<!--=========================================================================-->
272<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]273<a name="targetspecific">Other Target Specific Improvements</a>
274</div>
275
276<div class="doc_text">
277<p>New target-specific features include:
278</p>
279
280<ul>
281<li>The LLVM C backend now supports vectors code.</li>
282
283
284</ul>
285
286</div>
287
288
289
290<!--=========================================================================-->
291<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]292<a name="otherimprovements">Other Improvements</a>
293</div>
294
295<div class="doc_text">
296<p>New features include:
297</p>
298
299<ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]300<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]301<li>llvm2cpp tool was moved into llc, use llc -march=cpp</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]302</ul>
303
304</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]305
306<!-- *********************************************************************** -->
307<div class="doc_section">
308 <a name="portability">Portability and Supported Platforms</a>
309</div>
310<!-- *********************************************************************** -->
311
312<div class="doc_text">
313
314<p>LLVM is known to work on the following platforms:</p>
315
316<ul>
317<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
318 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]319<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]320 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]321<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]322<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
323 support is available for native builds with Visual C++).</li>
324<li>Sun UltraSPARC workstations running Solaris 8.</li>
325<li>Alpha-based machines running Debian GNU/Linux.</li>
326<li>Itanium-based machines running Linux and HP-UX.</li>
327</ul>
328
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]329<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]330to the machine and operating system on which it is built. However, minor
331porting may be required to get LLVM to work on new platforms. We welcome your
332portability patches and reports of successful builds or error messages.</p>
333
334</div>
335
336<!-- *********************************************************************** -->
337<div class="doc_section">
338 <a name="knownproblems">Known Problems</a>
339</div>
340<!-- *********************************************************************** -->
341
342<div class="doc_text">
343
344<p>This section contains all known problems with the LLVM system, listed by
345component. As new problems are discovered, they will be added to these
346sections. If you run into a problem, please check the <a
347href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
348there isn't already one.</p>
349
350</div>
351
352<!-- ======================================================================= -->
353<div class="doc_subsection">
354 <a name="experimental">Experimental features included with this release</a>
355</div>
356
357<div class="doc_text">
358
359<p>The following components of this LLVM release are either untested, known to
360be broken or unreliable, or are in early development. These components should
361not be relied on, and bugs should not be filed against them, but they may be
362useful 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]363components, please contact us on the <a
364href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]365
366<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]367<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]368<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
369 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]370</ul>
371
372</div>
373
374<!-- ======================================================================= -->
375<div class="doc_subsection">
376 <a name="x86-be">Known problems with the X86 back-end</a>
377</div>
378
379<div class="doc_text">
380
381<ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]382<li>The X86 backend does not yet support all <a
383 href="http://llvm.org/PR879">inline assembly that uses the X86 floating
384 point stack</a>. It supports the 'f' and 't' constraints, but not 'u'.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]385<li>The X86 backend generates inefficient floating point code when configured to
386 generate code for systems that don't have SSE2.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]387</ul>
388
389</div>
390
391<!-- ======================================================================= -->
392<div class="doc_subsection">
393 <a name="ppc-be">Known problems with the PowerPC back-end</a>
394</div>
395
396<div class="doc_text">
397
398<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]399<li>The Linux PPC32/ABI support needs testing for the interpreter and static
400compilation, and lacks support for debug information.</li>
401</ul>
402
403</div>
404
405<!-- ======================================================================= -->
406<div class="doc_subsection">
407 <a name="arm-be">Known problems with the ARM back-end</a>
408</div>
409
410<div class="doc_text">
411
412<ul>
413<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]414processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]415results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
416<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
417</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]418<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]419programs compiled with LLVM. Please use more recent versions of QEMU.</li>
420</ul>
421
422</div>
423
424<!-- ======================================================================= -->
425<div class="doc_subsection">
426 <a name="sparc-be">Known problems with the SPARC back-end</a>
427</div>
428
429<div class="doc_text">
430
431<ul>
432<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
433 support the 64-bit SPARC ABI (-m64).</li>
434</ul>
435
436</div>
437
438<!-- ======================================================================= -->
439<div class="doc_subsection">
440 <a name="alpha-be">Known problems with the Alpha back-end</a>
441</div>
442
443<div class="doc_text">
444
445<ul>
446
447<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
448appropriate nops inserted to ensure restartability.</li>
449
450</ul>
451</div>
452
453<!-- ======================================================================= -->
454<div class="doc_subsection">
455 <a name="ia64-be">Known problems with the IA64 back-end</a>
456</div>
457
458<div class="doc_text">
459
460<ul>
461
462<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
463made where the argument is not 16-byte aligned, as required on IA64. (Strictly
464speaking this is not a bug in the IA64 back-end; it will also be encountered
465when building C++ programs using the C back-end.)</li>
466
467<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
468ABI compliant layout of v-tables</a>. In particular, it just stores function
469pointers instead of function descriptors in the vtable. This bug prevents
470mixing C++ code compiled with LLVM with C++ objects compiled by other C++
471compilers.</li>
472
473<li>There are a few ABI violations which will lead to problems when mixing LLVM
474output with code built with other compilers, particularly for floating-point
475programs.</li>
476
477<li>Defining vararg functions is not supported (but calling them is ok).</li>
478
479<li>The Itanium backend has bitrotted somewhat.</li>
480</ul>
481
482</div>
483
484<!-- ======================================================================= -->
485<div class="doc_subsection">
486 <a name="c-be">Known problems with the C back-end</a>
487</div>
488
489<div class="doc_text">
490
491<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]492<li><a href="http://llvm.org/PR802">The C backend has only basic support for
493 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]494<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
495 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
496 C++ code compiled with LLC or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]497<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]498</ul>
499
500</div>
501
502
503<!-- ======================================================================= -->
504<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]505 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]506</div>
507
508<!-- _______________________________________________________________________ -->
509<div class="doc_subsubsection">Bugs</div>
510
511<div class="doc_text">
512
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]513<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
514Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]515llvmdev mailing list if you are interested.</p>
516
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]517<p>The only major language feature of GCC not supported by llvm-gcc is
518 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
519 are only supported on some targets. For example, trampolines are only
520 supported on some targets, which are used when you take the address of a
521 nested function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]522
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]523<p>If you run into GCC extensions which are not supported, please let us know.
524</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]525
526</div>
527
528<!-- ======================================================================= -->
529<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]530 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]531</div>
532
533<div class="doc_text">
534
535<p>The C++ front-end is considered to be fully
536tested and works for a number of non-trivial programs, including LLVM
537itself, Qt, Mozilla, etc.</p>
538
539<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]540<li>Exception handling works well on the X86 and PowerPC targets, including
541x86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
542supported on x86-64 linux, but that is disabled by default in this release.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]543</ul>
544
545</div>
546
547
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]548<!-- ======================================================================= -->
549<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]550 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]551</div>
552
553<div class="doc_text">
554The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
555technology and problems should be expected.
556<ul>
557<li>The Ada front-end currently only builds on x86-32. This is mainly due
558to lack of trampoline support (pointers to nested functions) on other platforms,
559however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
560which does support trampolines.</li>
561<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
562Workaround: configure with --disable-bootstrap.</li>
563<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
564fail (c380004 also fails with gcc-4.2 mainline).</li>
565<li>Many gcc specific Ada tests continue to crash the compiler.</li>
566<li>The -E binder option (exception backtraces)
567<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
568crashing if an exception is raised. Workaround: do not use -E.</li>
569<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
570or finish at a non-byte offset</a> in a record. Workaround: do not pack records
571or use representation clauses that result in a field of a non-discrete type
572starting or finishing in the middle of a byte.</li>
573<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
574as generated by the Ada binder to be invalid</a>.
575Workaround: hand edit the file to use pointers for argv and envp rather than
576integers.</li>
577<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
578</ul>
579</div>
580
581<!-- ======================================================================= -->
582<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]583 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]584</div>
585
586<div class="doc_text">
587
588<ul>
589<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
590<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
591</ul>
592</div>
593
594
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]595
596<!-- *********************************************************************** -->
597<div class="doc_section">
598 <a name="additionalinfo">Additional Information</a>
599</div>
600<!-- *********************************************************************** -->
601
602<div class="doc_text">
603
604<p>A wide variety of additional information is available on the <a
605href="http://llvm.org">LLVM web page</a>, in particular in the <a
606href="http://llvm.org/docs/">documentation</a> section. The web page also
607contains versions of the API documentation which is up-to-date with the
608Subversion version of the source code.
609You can access versions of these documents specific to this release by going
610into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
611
612<p>If you have any questions or comments about LLVM, please feel free to contact
613us via the <a href="http://llvm.org/docs/#maillist"> mailing
614lists</a>.</p>
615
616</div>
617
618<!-- *********************************************************************** -->
619
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