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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / f4aed1b492e3f3532da421b49300aba1bdd8b52c / . / 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>
Dan Gohmanf4aed1b2008-06-05 15:49:29 +0000[diff] [blame^]228<li>Alignment detection for vector memory references and for memcpy and
229memset is now more aggressive.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]230</ul>
231
232</div>
233
234
235<!--=========================================================================-->
236<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]237<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]238</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]239
240<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]241<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]242</p>
243
244<ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]245<li>llvm-gcc's X86-64 ABI conformance is far improved, particularly in the
246 area of passing and returning structures by value. llvm-gcc Compiled code
247 now interoperates very well on X86-64 systems with other compilers.</li>
248
249<li>The LLVM X86 backend now supports the support SSE 4.1 instruction set, and
250 the llvm-gcc 4.2 front-end supports the SSE 4.1 compiler builtins.</li>
251
252<li>The X86 backend now does a number of optimizations that aim to avoid
253 converting numbers back and forth from SSE registers to the X87 floating
254 point stack.</li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]255
256<li>The X86 backend supports stack realignment, which is particularly useful for
257 vector code on OS's without 16-byte aligned stacks.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]258
259<li>The X86 backend now supports the "sseregparm" options in GCC, which allow
260 functions to be tagged as passing floating point values in SSE
261 registers.</li>
262
263<li>Trampolines (taking the address of a nested function) now work on
264 Linux/x86-64.</li>
265
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]266<li><tt>__builtin_prefetch</tt> is now compiled into the appropriate prefetch
267 instructions instead of being ignored.</li>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]268
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]269</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]270
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]271</div>
272
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]273<!--=========================================================================-->
274<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]275<a name="targetspecific">Other Target Specific Improvements</a>
276</div>
277
278<div class="doc_text">
279<p>New target-specific features include:
280</p>
281
282<ul>
283<li>The LLVM C backend now supports vectors code.</li>
284
285
286</ul>
287
288</div>
289
290
291
292<!--=========================================================================-->
293<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]294<a name="otherimprovements">Other Improvements</a>
295</div>
296
297<div class="doc_text">
298<p>New features include:
299</p>
300
301<ul>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]302<li>LLVM now builds with GCC 4.3.</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]303<li>llvm2cpp tool was moved into llc, use llc -march=cpp</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]304</ul>
305
306</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]307
308<!-- *********************************************************************** -->
309<div class="doc_section">
310 <a name="portability">Portability and Supported Platforms</a>
311</div>
312<!-- *********************************************************************** -->
313
314<div class="doc_text">
315
316<p>LLVM is known to work on the following platforms:</p>
317
318<ul>
319<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
320 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]321<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]322 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]323<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]324<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
325 support is available for native builds with Visual C++).</li>
326<li>Sun UltraSPARC workstations running Solaris 8.</li>
327<li>Alpha-based machines running Debian GNU/Linux.</li>
328<li>Itanium-based machines running Linux and HP-UX.</li>
329</ul>
330
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]331<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]332to the machine and operating system on which it is built. However, minor
333porting may be required to get LLVM to work on new platforms. We welcome your
334portability patches and reports of successful builds or error messages.</p>
335
336</div>
337
338<!-- *********************************************************************** -->
339<div class="doc_section">
340 <a name="knownproblems">Known Problems</a>
341</div>
342<!-- *********************************************************************** -->
343
344<div class="doc_text">
345
346<p>This section contains all known problems with the LLVM system, listed by
347component. As new problems are discovered, they will be added to these
348sections. If you run into a problem, please check the <a
349href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
350there isn't already one.</p>
351
352</div>
353
354<!-- ======================================================================= -->
355<div class="doc_subsection">
356 <a name="experimental">Experimental features included with this release</a>
357</div>
358
359<div class="doc_text">
360
361<p>The following components of this LLVM release are either untested, known to
362be broken or unreliable, or are in early development. These components should
363not be relied on, and bugs should not be filed against them, but they may be
364useful 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]365components, please contact us on the <a
366href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]367
368<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]369<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]370<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
371 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]372</ul>
373
374</div>
375
376<!-- ======================================================================= -->
377<div class="doc_subsection">
378 <a name="x86-be">Known problems with the X86 back-end</a>
379</div>
380
381<div class="doc_text">
382
383<ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]384<li>The X86 backend does not yet support all <a
385 href="http://llvm.org/PR879">inline assembly that uses the X86 floating
386 point stack</a>. It supports the 'f' and 't' constraints, but not 'u'.</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]387<li>The X86 backend generates inefficient floating point code when configured to
388 generate code for systems that don't have SSE2.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]389</ul>
390
391</div>
392
393<!-- ======================================================================= -->
394<div class="doc_subsection">
395 <a name="ppc-be">Known problems with the PowerPC back-end</a>
396</div>
397
398<div class="doc_text">
399
400<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]401<li>The Linux PPC32/ABI support needs testing for the interpreter and static
402compilation, and lacks support for debug information.</li>
403</ul>
404
405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="arm-be">Known problems with the ARM back-end</a>
410</div>
411
412<div class="doc_text">
413
414<ul>
415<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]416processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]417results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
418<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
419</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]420<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]421programs compiled with LLVM. Please use more recent versions of QEMU.</li>
422</ul>
423
424</div>
425
426<!-- ======================================================================= -->
427<div class="doc_subsection">
428 <a name="sparc-be">Known problems with the SPARC back-end</a>
429</div>
430
431<div class="doc_text">
432
433<ul>
434<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
435 support the 64-bit SPARC ABI (-m64).</li>
436</ul>
437
438</div>
439
440<!-- ======================================================================= -->
441<div class="doc_subsection">
442 <a name="alpha-be">Known problems with the Alpha back-end</a>
443</div>
444
445<div class="doc_text">
446
447<ul>
448
449<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
450appropriate nops inserted to ensure restartability.</li>
451
452</ul>
453</div>
454
455<!-- ======================================================================= -->
456<div class="doc_subsection">
457 <a name="ia64-be">Known problems with the IA64 back-end</a>
458</div>
459
460<div class="doc_text">
461
462<ul>
463
464<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
465made where the argument is not 16-byte aligned, as required on IA64. (Strictly
466speaking this is not a bug in the IA64 back-end; it will also be encountered
467when building C++ programs using the C back-end.)</li>
468
469<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
470ABI compliant layout of v-tables</a>. In particular, it just stores function
471pointers instead of function descriptors in the vtable. This bug prevents
472mixing C++ code compiled with LLVM with C++ objects compiled by other C++
473compilers.</li>
474
475<li>There are a few ABI violations which will lead to problems when mixing LLVM
476output with code built with other compilers, particularly for floating-point
477programs.</li>
478
479<li>Defining vararg functions is not supported (but calling them is ok).</li>
480
481<li>The Itanium backend has bitrotted somewhat.</li>
482</ul>
483
484</div>
485
486<!-- ======================================================================= -->
487<div class="doc_subsection">
488 <a name="c-be">Known problems with the C back-end</a>
489</div>
490
491<div class="doc_text">
492
493<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]494<li><a href="http://llvm.org/PR802">The C backend has only basic support for
495 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]496<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
497 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
498 C++ code compiled with LLC or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]499<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]500</ul>
501
502</div>
503
504
505<!-- ======================================================================= -->
506<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]507 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]508</div>
509
510<!-- _______________________________________________________________________ -->
511<div class="doc_subsubsection">Bugs</div>
512
513<div class="doc_text">
514
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]515<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
516Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]517llvmdev mailing list if you are interested.</p>
518
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]519<p>The only major language feature of GCC not supported by llvm-gcc is
520 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
521 are only supported on some targets. For example, trampolines are only
522 supported on some targets, which are used when you take the address of a
523 nested function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]524
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]525<p>If you run into GCC extensions which are not supported, please let us know.
526</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]527
528</div>
529
530<!-- ======================================================================= -->
531<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]532 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]533</div>
534
535<div class="doc_text">
536
537<p>The C++ front-end is considered to be fully
538tested and works for a number of non-trivial programs, including LLVM
539itself, Qt, Mozilla, etc.</p>
540
541<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]542<li>Exception handling works well on the X86 and PowerPC targets, including
543x86-64 darwin. This works when linking to a libstdc++ compiled by GCC. It is
544supported on x86-64 linux, but that is disabled by default in this release.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]545</ul>
546
547</div>
548
549
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]550<!-- ======================================================================= -->
551<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]552 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]553</div>
554
555<div class="doc_text">
556The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
557technology and problems should be expected.
558<ul>
559<li>The Ada front-end currently only builds on x86-32. This is mainly due
560to lack of trampoline support (pointers to nested functions) on other platforms,
561however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
562which does support trampolines.</li>
563<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
564Workaround: configure with --disable-bootstrap.</li>
565<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
566fail (c380004 also fails with gcc-4.2 mainline).</li>
567<li>Many gcc specific Ada tests continue to crash the compiler.</li>
568<li>The -E binder option (exception backtraces)
569<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
570crashing if an exception is raised. Workaround: do not use -E.</li>
571<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
572or finish at a non-byte offset</a> in a record. Workaround: do not pack records
573or use representation clauses that result in a field of a non-discrete type
574starting or finishing in the middle of a byte.</li>
575<li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
576as generated by the Ada binder to be invalid</a>.
577Workaround: hand edit the file to use pointers for argv and envp rather than
578integers.</li>
579<li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
580</ul>
581</div>
582
583<!-- ======================================================================= -->
584<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]585 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]586</div>
587
588<div class="doc_text">
589
590<ul>
591<li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
592<a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
593</ul>
594</div>
595
596
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]597
598<!-- *********************************************************************** -->
599<div class="doc_section">
600 <a name="additionalinfo">Additional Information</a>
601</div>
602<!-- *********************************************************************** -->
603
604<div class="doc_text">
605
606<p>A wide variety of additional information is available on the <a
607href="http://llvm.org">LLVM web page</a>, in particular in the <a
608href="http://llvm.org/docs/">documentation</a> section. The web page also
609contains versions of the API documentation which is up-to-date with the
610Subversion version of the source code.
611You can access versions of these documents specific to this release by going
612into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
613
614<p>If you have any questions or comments about LLVM, please feel free to contact
615us via the <a href="http://llvm.org/docs/#maillist"> mailing
616lists</a>.</p>
617
618</div>
619
620<!-- *********************************************************************** -->
621
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