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Chris Lattnercaf06342007-05-09 04:58:11 +00007 <title>LLVM 2.0 Release Notes</title>
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9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +000010
Chris Lattnercaf06342007-05-09 04:58:11 +000011<div class="doc_title">LLVM 2.0 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000012
13<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000014 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +000016 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +000017 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000018 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +000019 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000020</ol>
21
Chris Lattner7911ce22004-05-23 21:07:27 +000022<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +000023 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +000024</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000025
26<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000027<div class="doc_section">
28 <a name="intro">Introduction</a>
29</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000030<!-- *********************************************************************** -->
31
Misha Brukman500bc302003-11-22 00:38:41 +000032<div class="doc_text">
33
34<p>This document contains the release notes for the LLVM compiler
Chris Lattnercaf06342007-05-09 04:58:11 +000035infrastructure, release 2.0. Here we describe the status of LLVM, including any
36known problems and major improvements from the previous release. All LLVM
37releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
38releases web site</a>.
Chris Lattner19092612003-10-02 16:38:05 +000039
Chris Lattner7506b1d2004-12-07 08:04:13 +000040<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000041release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000042web site</a>. If you have questions or comments, the <a
43href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +000044list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000045
Chris Lattner78bf32b2004-12-09 22:22:58 +000046<p>Note that if you are reading this file from CVS or the main LLVM web page,
47this document applies to the <i>next</i> release, not the current one. To see
48the release notes for the current or previous releases, see the <a
Chris Lattnerc463b272005-10-29 07:07:09 +000049href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +000050
51</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000052
53<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000054<div class="doc_section">
55 <a name="whatsnew">What's New?</a>
56</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000057<!-- *********************************************************************** -->
58
Misha Brukman500bc302003-11-22 00:38:41 +000059<div class="doc_text">
60
Chris Lattnercaf06342007-05-09 04:58:11 +000061<p>This is the eleventh public release of the LLVM Compiler Infrastructure.
Chris Lattnerf01b0b52007-05-09 05:27:05 +000062Being the first major release since 1.0, this release is different in several
63ways from our previous releases:</p>
64
65<ol>
66<li>We took this as an opportunity to
Chris Lattnercaf06342007-05-09 04:58:11 +000067break backwards compatibility with the LLVM 1.x bytecode and .ll file format.
68If you have LLVM 1.9 .ll files that you would like to upgrade to LLVM 2.x, we
Lauro Ramos Venanciobe1b1b12007-05-12 02:36:41 +000069recommend the use of the stand alone <a href="#llvm-upgrade">llvm-upgrade</a>
Chris Lattnercaf06342007-05-09 04:58:11 +000070tool. We intend to keep compatibility with .ll and .bc formats within the 2.x
Chris Lattnerf01b0b52007-05-09 05:27:05 +000071release series, like we did within the 1.x series.</li>
72<li>There are several significant change to the LLVM IR and internal APIs, such
73 as a major overhaul of the type system, the completely new bitcode file
74 format, etc.</li>
75<li>We designed the release around a 6 month release cycle instead of the usual
76 3-month cycle. This gave us extra time to develop and test some of the
77 more invasive features in this release.</li>
78<li>LLVM 2.0 no longer supports the llvm-gcc3 front-end.</li>
79</ol>
Chris Lattnercaf06342007-05-09 04:58:11 +000080
Chris Lattnerf01b0b52007-05-09 05:27:05 +000081<p>Note that while this is a major version bump, this release has been
82 extensively tested on a wide range of software. It is easy to say that this
83 is our best release yet, in terms of both features and correctness.</p>
Chris Lattnera5099962003-12-06 20:22:41 +000084
Chris Lattner80453c92004-05-24 04:50:25 +000085</div>
86
Chris Lattnera5099962003-12-06 20:22:41 +000087<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +000088<div class="doc_subsection">
Chris Lattnercaf06342007-05-09 04:58:11 +000089<a name="newfeatures">New Features in LLVM 2.0</a>
Chris Lattner44c933e2006-04-18 06:18:36 +000090</div>
91
Chris Lattner738bd302006-04-18 06:32:08 +000092<!--_________________________________________________________________________-->
Chris Lattner26299222006-11-18 07:51:14 +000093<div class="doc_subsubsection"><a name="optimizer">Optimizer
94Improvements</a></div>
Chris Lattner738bd302006-04-18 06:32:08 +000095<div class="doc_text">
Chris Lattner26299222006-11-18 07:51:14 +000096<p>The mid-level optimizer is now faster and produces better code in many cases.
97 Significant changes include:</p>
98
99<ul>
Chris Lattnercaf06342007-05-09 04:58:11 +0000100<li></li>
Chris Lattner26299222006-11-18 07:51:14 +0000101</ul>
102
Chris Lattner738bd302006-04-18 06:32:08 +0000103</div>
104
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000105<!--_________________________________________________________________________-->
Chris Lattner26299222006-11-18 07:51:14 +0000106<div class="doc_subsubsection"><a name="codegen">Code
107Generator Enhancements</a></div>
108
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000109<div class="doc_text">
Chris Lattner26299222006-11-18 07:51:14 +0000110<p>
111The LLVM Target-Independent code generator now supports more target features and
112optimizes many cases more aggressively. New features include:
113</p>
114
115<ul>
Chris Lattnercaf06342007-05-09 04:58:11 +0000116<li></li>
Chris Lattner26299222006-11-18 07:51:14 +0000117</ul>
118
119<p>In addition, the LLVM target description format has itself been extended in
120 several ways:</p>
121
122<ul>
Chris Lattnercaf06342007-05-09 04:58:11 +0000123<li></li>
Chris Lattner26299222006-11-18 07:51:14 +0000124</ul>
125
126<p>Further, several significant target-specific enhancements are included in
Chris Lattnercaf06342007-05-09 04:58:11 +0000127LLVM 2.0:</p>
Chris Lattner26299222006-11-18 07:51:14 +0000128
129<ul>
Chris Lattnercaf06342007-05-09 04:58:11 +0000130<li></li>
Chris Lattner26299222006-11-18 07:51:14 +0000131</ul>
132
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000133</div>
Chris Lattner44c933e2006-04-18 06:18:36 +0000134
135<!--_________________________________________________________________________-->
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000136<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
Chris Lattner58504a62006-02-05 06:39:36 +0000137<div class="doc_text">
Chris Lattnercaf06342007-05-09 04:58:11 +0000138<p></p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000139
140<p>More specific changes include:</p>
141
Chris Lattner58504a62006-02-05 06:39:36 +0000142<ul>
Chris Lattnercaf06342007-05-09 04:58:11 +0000143<li></li>
Chris Lattner58504a62006-02-05 06:39:36 +0000144</ul>
145</div>
John Criswelle531ec52005-06-29 16:22:34 +0000146
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000147
148
Chris Lattner19092612003-10-02 16:38:05 +0000149<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000150<div class="doc_section">
151 <a name="portability">Portability and Supported Platforms</a>
152</div>
Chris Lattner19092612003-10-02 16:38:05 +0000153<!-- *********************************************************************** -->
154
Misha Brukman500bc302003-11-22 00:38:41 +0000155<div class="doc_text">
156
John Criswell0b5b5e92004-12-08 20:35:47 +0000157<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000158
159<ul>
Reid Spencer00812e22005-05-17 02:47:27 +0000160 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
161 (and probably other unix-like systems).</li>
Chris Lattner7ea41e32006-08-09 04:10:32 +0000162<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000163<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000164<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
165 support is available for native builds with Visual C++).</li>
Chris Lattner26299222006-11-18 07:51:14 +0000166<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
167 64-bit modes.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000168<li>Alpha-based machines running Debian GNU/Linux.</li>
169<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000170</ul>
171
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000172<p>The core LLVM infrastructure uses
173<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
174to the machine and operating system on which it is built. However, minor
175porting may be required to get LLVM to work on new platforms. We welcome your
176portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000177
Misha Brukman500bc302003-11-22 00:38:41 +0000178</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000179
180<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000181<div class="doc_section">
182 <a name="knownproblems">Known Problems</a>
183</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000184<!-- *********************************************************************** -->
185
Misha Brukman500bc302003-11-22 00:38:41 +0000186<div class="doc_text">
187
188<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000189component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000190sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000191href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000192there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000193
Misha Brukman500bc302003-11-22 00:38:41 +0000194</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000195
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000196<!-- ======================================================================= -->
197<div class="doc_subsection">
198 <a name="experimental">Experimental features included with this release</a>
199</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000200
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000201<div class="doc_text">
202
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000203<p>The following components of this LLVM release are either untested, known to
204be broken or unreliable, or are in early development. These components should
205not be relied on, and bugs should not be filed against them, but they may be
206useful to some people. In particular, if you would like to work on one of these
Chris Lattner49e693e2006-08-09 04:08:52 +0000207components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000208
209<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000210<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
211 future release.</li>
Chris Lattner0d77e052007-05-09 06:23:58 +0000212<li>C++ EH support</li>
Chris Lattner58504a62006-02-05 06:39:36 +0000213<li>The IA64 code generator is experimental.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000214<li>The Alpha JIT is experimental.</li>
Chris Lattner44c933e2006-04-18 06:18:36 +0000215<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
216 <tt>-filetype</tt> llc option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000217</ul>
218
219</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000220
Misha Brukman500bc302003-11-22 00:38:41 +0000221<!-- ======================================================================= -->
222<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000223 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000224</div>
225
226<div class="doc_text">
227
228<ul>
Chris Lattner26299222006-11-18 07:51:14 +0000229<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
Chris Lattnercaf06342007-05-09 04:58:11 +0000230 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000231</ul>
232
233</div>
234
235<!-- ======================================================================= -->
236<div class="doc_subsection">
237 <a name="ppc-be">Known problems with the PowerPC back-end</a>
238</div>
239
240<div class="doc_text">
241
242<ul>
243<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
244implement ordered FP comparisons</a>.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000245</ul>
246
247</div>
248
249<!-- ======================================================================= -->
250<div class="doc_subsection">
251 <a name="sparc-be">Known problems with the SPARC back-end</a>
252</div>
253
254<div class="doc_text">
255
256<ul>
257<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
258 support the 64-bit SPARC ABI (-m64).</li>
259</ul>
260
261</div>
262
263<!-- ======================================================================= -->
264<div class="doc_subsection">
265 <a name="c-be">Known problems with the C back-end</a>
266</div>
267
268<div class="doc_text">
269
270<ul>
271
272<li>The C back-end produces code that violates the ANSI C Type-Based Alias
273Analysis rules. As such, special options may be necessary to compile the code
274(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
275problem probably cannot be fixed.</li>
276
277<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
278supported</a>. This should not affect LLVM produced by the C or C++
279frontends.</li>
280
281<li>The C backend does not correctly implement the <a
Reid Spencer62ea8b62007-04-04 04:14:31 +0000282href="LangRef.html#int_stacksave"><tt>llvm.stacksave</tt></a> or
283<a href="LangRef.html#int_stackrestore"><tt>llvm.stackrestore</tt></a>
Chris Lattner26299222006-11-18 07:51:14 +0000284intrinsics. This means that some code compiled by it can run out of stack
285space if they depend on these (e.g. C99 varargs).</li>
286
287<li><a href="http://llvm.org/PR802">The C backend does not support inline
288 assembly code</a>.</li>
289</ul>
290
291</div>
292
293<!-- ======================================================================= -->
294<div class="doc_subsection">
295 <a name="alpha-be">Known problems with the Alpha back-end</a>
296</div>
297
298<div class="doc_text">
299
300<ul>
301
302<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
303appropriate nops inserted to ensure restartability.</li>
304
John Criswellc0c186d2005-11-08 21:11:33 +0000305</ul>
306</div>
307
Chris Lattner26299222006-11-18 07:51:14 +0000308<!-- ======================================================================= -->
309<div class="doc_subsection">
310 <a name="ia64-be">Known problems with the IA64 back-end</a>
311</div>
312
313<div class="doc_text">
314
315<ul>
316
317<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
318made where the argument is not 16-byte aligned, as required on IA64. (Strictly
319speaking this is not a bug in the IA64 back-end; it will also be encountered
320when building C++ programs using the C back-end.)</li>
321
322<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
323ABI compliant layout of v-tables</a>. In particular, it just stores function
324pointers instead of function descriptors in the vtable. This bug prevents
325mixing C++ code compiled with LLVM with C++ objects compiled by other C++
326compilers.</li>
327
328<li>There are a few ABI violations which will lead to problems when mixing LLVM
329output with code built with other compilers, particularly for floating-point
330programs.</li>
331
332<li>Defining vararg functions is not supported (but calling them is ok).</li>
333
Chris Lattnercaf06342007-05-09 04:58:11 +0000334<li>The Itanium backend has bitrotted somewhat.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000335</ul>
336
337</div>
338
339<!-- ======================================================================= -->
340<div class="doc_subsection">
341 <a name="arm-be">Known problems with the ARM back-end</a>
342</div>
343
344<div class="doc_text">
345
346<ul>
Lauro Ramos Venancioab5063b2007-05-09 19:31:58 +0000347<li>The Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
348processors, any thumb program compiled with LLVM crashes or produces wrong
349results. (<a href="http://llvm.org/PR1388">PR1388</a>)</li>
350<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
351</li>
Lauro Ramos Venanciobe1b1b12007-05-12 02:36:41 +0000352<li>QEMU-ARM (<= 0.9.0) wrongly executes programs compiled with LLVM. A non-affected QEMU version must be used or this
353<a href="http://cvs.savannah.nongnu.org/viewcvs/qemu/target-arm/translate.c?root=qemu&r1=1.46&r2=1.47&makepatch=1&diff_format=h">
354patch</a> must be applied on QEMU.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000355</ul>
356
357</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000358
359<!-- ======================================================================= -->
360<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000361 <a name="core">Known problems with the LLVM Core</a>
362</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000363
Misha Brukman500bc302003-11-22 00:38:41 +0000364<div class="doc_text">
365
366<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000367 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
368 work.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000369</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000370</div>
371
372<!-- ======================================================================= -->
373<div class="doc_subsection">
374 <a name="c-fe">Known problems with the C front-end</a>
375</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000376
Chris Lattner79c3fe12003-10-02 04:57:28 +0000377<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000378<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000379
Misha Brukman500bc302003-11-22 00:38:41 +0000380<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000381
Chris Lattner44c933e2006-04-18 06:18:36 +0000382<p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000383
384<p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
Chris Lattner26299222006-11-18 07:51:14 +0000385does not currently support <a href="http://llvm.org/PR869">Link-Time
386Optimization</a> or <a href="http://llvm.org/PR870">C++ Exception Handling</a>,
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000387which llvm-gcc3 does.</p>
388
Chris Lattner26299222006-11-18 07:51:14 +0000389<p>llvm-gcc4 does not support the <a href="http://llvm.org/PR947">GCC indirect
390goto extension</a>, but llvm-gcc3 does.</p>
391
Misha Brukman500bc302003-11-22 00:38:41 +0000392</div>
393
394<!-- _______________________________________________________________________ -->
395<div class="doc_subsubsection">
396 Notes
397</div>
398
399<div class="doc_text">
400
401<ul>
402
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000403<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000404support for floating point data types of any size other than 32 and 64
405bits.</li>
406
Chris Lattner79c3fe12003-10-02 04:57:28 +0000407<li>Although many GCC extensions are supported, some are not. In particular,
408 the following extensions are known to <b>not be</b> supported:
409 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000410 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000411 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.</li>
412 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
Tanya Lattner014e5f52004-12-08 18:25:34 +0000413 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000414 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000415 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000416
Misha Brukman500bc302003-11-22 00:38:41 +0000417 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000418 attribute means that the LLVM compiler ignores the presence of the attribute,
419 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000420 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000421 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000422
423 <ol>
424 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
425 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000426 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000427
428 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000429
John Criswelld000e1d2003-12-18 16:43:17 +0000430 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000431 return.<br>
432
Anton Korobeynikov9ec81372007-05-10 08:26:24 +0000433 <b>Supported:</b> <tt>alias</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Anton Korobeynikov9413de32006-11-18 08:04:48 +0000434 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikov9ec81372007-05-10 08:26:24 +0000435 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noreturn</tt>, <tt>regparm</tt>
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000436 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
437 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000438
John Criswell0b5b5e92004-12-08 20:35:47 +0000439 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000440 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
441 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
442
Anton Korobeynikov9ec81372007-05-10 08:26:24 +0000443 <b>Unsupported:</b> All other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000444
445 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
446 Specifying attributes of variables.<br>
Anton Korobeynikov9ec81372007-05-10 08:26:24 +0000447 <b>Supported:</b> <tt>alias</tt>, <tt>cleanup</tt>, <tt>common</tt>,
448 <tt>nocommon</tt>, <tt>deprecated</tt>, <tt>dllimport</tt>,
449 <tt>dllexport</tt>, <tt>section</tt>, <tt>transparent_union</tt>,
450 <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000451
Chris Lattner79c3fe12003-10-02 04:57:28 +0000452 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000453 <tt>shared</tt>, <tt>tls_model</tt>,
454 <tt>vector_size</tt>, all target specific attributes.
Anton Korobeynikov9413de32006-11-18 08:04:48 +0000455 </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000456
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000458 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000459 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000460
461 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
462 all target specific attributes.</li>
463
Chris Lattner79c3fe12003-10-02 04:57:28 +0000464 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
465 Other built-in functions.<br>
466 We support all builtins which have a C language equivalent (e.g.,
467 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
468 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000469 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
470 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000471 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
472 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
473 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000474 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000475
Misha Brukman500bc302003-11-22 00:38:41 +0000476 <p>The following extensions <b>are</b> known to be supported:</p>
477
Chris Lattner79c3fe12003-10-02 04:57:28 +0000478 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000479 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000480 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
481 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
Tanya Lattnerca26c3e2004-06-22 03:48:17 +0000482 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000483 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
484 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
485 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
486 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
487 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
488 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
490 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000491 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
492 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
494 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
496 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000497 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000500 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
501or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000502 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000503 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000504 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
505 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
506 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
Tanya Lattner78537e42004-12-08 18:29:38 +0000507 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000508 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character &lt;ESC&gt;.</li>
510 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
511 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
512 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
514 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
Chris Lattner25795bc2004-02-14 04:08:29 +0000515 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000516 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
517 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000518 </ol></li>
519
520</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000521
Misha Brukman500bc302003-11-22 00:38:41 +0000522<p>If you run into GCC extensions which have not been included in any of these
523lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000524
Misha Brukman500bc302003-11-22 00:38:41 +0000525</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000526
Misha Brukman500bc302003-11-22 00:38:41 +0000527<!-- ======================================================================= -->
528<div class="doc_subsection">
529 <a name="c++-fe">Known problems with the C++ front-end</a>
530</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000531
Misha Brukman500bc302003-11-22 00:38:41 +0000532<div class="doc_text">
533
Reid Spencere09ca642004-12-07 08:39:08 +0000534<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000535tested and works for a number of non-trivial programs, including LLVM
536itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000537
538</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000539
540<!-- _______________________________________________________________________ -->
Misha Brukman500bc302003-11-22 00:38:41 +0000541<div class="doc_subsubsection">
542 Notes
543</div>
544
545<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000546<ul>
Chris Lattner26299222006-11-18 07:51:14 +0000547<li>llvm-gcc4 does not support C++ exception handling at all yet.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000548
Chris Lattner79c3fe12003-10-02 04:57:28 +0000549<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000550 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000551 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000552 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000553 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000554
Chris Lattner19092612003-10-02 16:38:05 +0000555<li>The LLVM C++ front-end follows the <a
556 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
557 This document, which is not Itanium specific, specifies a standard for name
558 mangling, class layout, v-table layout, RTTI formats, and other C++
559 representation issues. Because we use this API, code generated by the LLVM
560 compilers should be binary compatible with machine code generated by other
561 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
Chris Lattner26299222006-11-18 07:51:14 +0000562 <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
Chris Lattner19092612003-10-02 16:38:05 +0000563 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000564 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000565
Misha Brukman500bc302003-11-22 00:38:41 +0000566</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000567
Misha Brukman500bc302003-11-22 00:38:41 +0000568</div>
569
Misha Brukman500bc302003-11-22 00:38:41 +0000570
Chris Lattner98a493c2005-05-15 16:01:20 +0000571
Chris Lattner79c3fe12003-10-02 04:57:28 +0000572<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000573<div class="doc_section">
574 <a name="additionalinfo">Additional Information</a>
575</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000576<!-- *********************************************************************** -->
577
Misha Brukman500bc302003-11-22 00:38:41 +0000578<div class="doc_text">
579
Chris Lattner416db102005-05-16 17:13:10 +0000580<p>A wide variety of additional information is available on the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000581href="http://llvm.org">LLVM web page</a>, including <a
582href="http://llvm.org/docs/">documentation</a> and <a
583href="http://llvm.org/pubs/">publications describing algorithms and
Misha Brukman109d9e82005-03-30 19:14:24 +0000584components implemented in LLVM</a>. The web page also contains versions of the
585API documentation which is up-to-date with the CVS version of the source code.
586You can access versions of these documents specific to this release by going
587into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000588
Misha Brukman500bc302003-11-22 00:38:41 +0000589<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000590us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000591lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000592
Misha Brukman500bc302003-11-22 00:38:41 +0000593</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000594
595<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000596
Misha Brukman500bc302003-11-22 00:38:41 +0000597<hr>
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Chris Lattnerc463b272005-10-29 07:07:09 +0000604 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
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