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Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]6 <title>LLVM 1.3 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]7</head>
8<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]9
Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]10<div class="doc_title">LLVM 1.3 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]11
12<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]13 <li><a href="#intro">Introduction</a></li>
14 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]15 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]16 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]17 <li><a href="#knownproblems">Known Problems</a>
18 <ul>
Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]19 <li><a href="#experimental">Experimental features included in this
20 release</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]21 <li><a href="#core">Known problems with the LLVM Core</a>
22 <li><a href="#c-fe">Known problems with the C Front-end</a>
23 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
24 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
25 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
26 <li><a href="#c-be">Known problems with the C back-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]27 </ul></li>
28 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]29</ol>
30
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]31<div class="doc_text">
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]32 <p><b>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM team</a></b><p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]33</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]34
35<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]36<div class="doc_section">
37 <a name="intro">Introduction</a>
38</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]39<!-- *********************************************************************** -->
40
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]41<div class="doc_text">
42
43<p>This document contains the release notes for the LLVM compiler
Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]44infrastructure, release 1.3. Here we describe the status of LLVM, including any
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]45known problems and bug fixes from the previous release. The most up-to-date
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]46version of this document can be found on the <a
Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]47href="http://llvm.cs.uiuc.edu/releases/1.3/">LLVM 1.3 web site</a>. If you are
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]48not reading this on the LLVM web pages, you should probably go there because
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]49this document may be updated after the release.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]50
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]51<p>For more information about LLVM, including information about potentially more
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]52current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
53web site</a>. If you have questions or comments, the <a
54href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]55list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]56
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]57<p>Note that if you are reading this file from CVS, this document applies
58to the <i>next</i> release, not the current one. To see the release notes for
59the current or previous releases, see the <a
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]60href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
61
62</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]63
64<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]65<div class="doc_section">
66 <a name="whatsnew">What's New?</a>
67</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]68<!-- *********************************************************************** -->
69
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]70<div class="doc_text">
71
Chris Lattnera39719f2004-02-25 16:36:51 +0000[diff] [blame]72<p>
Chris Lattnerd4594dc2004-05-04 17:04:09 +0000[diff] [blame]73This is the fourth public release of the LLVM compiler infrastructure. This
74release primarily improves the <a href="#codequality">performance of the
75code</a> produced by all aspects of the LLVM compiler and adds some <a
76href="#newfeatures">new features</a>, though it does <a href="#bugfix">fix a few
77bugs</a> as well.
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]78</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]79
Chris Lattner835104c2004-03-17 03:54:41 +0000[diff] [blame]80<p>
81At this time, LLVM is known to correctly compile and run all C &amp; C++ SPEC
82CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist benchmarks. It has
83also been used to compile <b>many</b> other programs. LLVM now also works with
84a broad variety of C++ programs, though it has still received less testing than
85the C front-end.
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]86</p>
87
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]88<!--=========================================================================-->
89<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000[diff] [blame]90<a name="newfeatures">This release implements the following new features:</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]91</div>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]92
93<ol>
Chris Lattner2974b5b2004-04-01 00:41:31 +0000[diff] [blame]94<li>The LLVM <a href="LangRef.html#i_select"><tt>select</tt></a> instruction is
Chris Lattner6e1ef192004-05-02 04:19:15 +0000[diff] [blame]95now fully implemented and supported by all transformations, native code
96generators, and the interpreter.</li>
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]97<li>Bugpoint can now narrow down code-generation bugs to a loop nest, where
98before it could only narrow them down to a function being miscompiled.</li>
Brian Gaeke43be3112004-05-04 21:22:57 +0000[diff] [blame^]99<li><a href="http://llvm.cs.uiuc.edu/PR40">Bugpoint can now debug arbitrary
100modes of llc</a> and lli, by passing them command line flags (e.g.,
101<tt>-regalloc=linearscan</tt>, <tt>-enable-correct-eh-support</tt>, etc.) </li>
Chris Lattner6e1ef192004-05-02 04:19:15 +0000[diff] [blame]102<li>The Control Flow Graph in the native code generators is no longer
103constrained to be the same as the CFG for the LLVM input code.</li>
104<li>The LLVM induction variable analysis routines have been rewritten.</li>
105<li>LLVM now has new loop unrolling and loop unswitching passes.</li>
106<li>The induction variable substitution pass performs linear function test
107replacement and exit value replacement optimizations.</li>
Chris Lattner55ee0312003-11-19 22:05:38 +0000[diff] [blame]108</ol>
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]109
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]110
111<!--=========================================================================-->
112<div class="doc_subsubsection">
113In this release, the following missing features were implemented:
114</div>
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]115
116<ol>
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]117<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
118more than 256 elements</a></li>
Misha Brukmancb003362004-04-19 03:01:01 +0000[diff] [blame]119<li><a href="http://llvm.cs.uiuc.edu/PR38">[bugpoint] External functions used in
120non-instruction entities, such as global constant initializer</a></li>
121<li><a href="http://llvm.cs.uiuc.edu/PR290">Bugpoint doesn't support
122uses of external fns by immediate constant exprs</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]123</ol>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]124
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]125
126<!--=========================================================================-->
127<div class="doc_subsubsection">
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]128<a name="qualityofimp">In this release, the following Quality of Implementation
129issues were fixed:</a>
Chris Lattnere29ac162003-12-20 03:42:11 +0000[diff] [blame]130</div>
131
132<ol>
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]133<li><a href="http://llvm.cs.uiuc.edu/PR305">LLVM tools will happily spew
134bytecode onto your terminal</a></li>
Chris Lattnere29ac162003-12-20 03:42:11 +0000[diff] [blame]135</ol>
136
137<!--=========================================================================-->
138<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000[diff] [blame]139In this release, the following build problems were fixed:
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]140</div>
141
142<ol>
Brian Gaeke21a710a2004-04-20 18:18:46 +0000[diff] [blame]143<li><a href="http://llvm.cs.uiuc.edu/PR301">Minor configure bugs with -disable/enable-povray and -disable-spec</a></li>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]144</ol>
145
146<!--=========================================================================-->
147<div class="doc_subsubsection">
Chris Lattner6e1ef192004-05-02 04:19:15 +0000[diff] [blame]148<a name="codequality">This release includes the following Code Quality
149improvements:</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]150</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]151
152<ol>
Chris Lattner6e1ef192004-05-02 04:19:15 +0000[diff] [blame]153<li>Fixed: <a href="http://llvm.cs.uiuc.edu/PR309">[vmcore] Code quality problem
154due to long operand of getelementptr</a></li>
Chris Lattner64913402004-04-13 14:43:35 +0000[diff] [blame]155
156<li>The X86 backend now generates substantially better code for 64-bit integer
157and floating point operations.</li>
158
159<li>The -inline pass no longer inlines mutually recursive functions until it
160hits the inlining threshold.</li>
161
162<li>The -inline pass no longer misses obvious inlining opportunities just
163because the callee eventually calls into an external function.</li>
164
165<li>The -simplifycfg pass can now "if convert" simple statements into the new
166<tt>select</tt> instruction.</li>
167
168<li>The -loopsimplify pass can now break <a
169href="http://llvm.cs.uiuc.edu/PR35">natural loops with multiple backedges</a>
170into multiple nested loops. This enables a variety of subsequent
171optimizations.</li>
172
173<li>The -adce pass can now eliminate calls to functions that do not not write to
174memory.</li>
175
176<li>The link-time optimizer now runs the -prune-eh pass (to remove unused
Chris Lattnerd4594dc2004-05-04 17:04:09 +0000[diff] [blame]177exception handlers).</li>
Chris Lattner64913402004-04-13 14:43:35 +0000[diff] [blame]178
Chris Lattner6e1ef192004-05-02 04:19:15 +0000[diff] [blame]179<li>The -simplifycfg pass can now eliminate simple correlated branches (such as
180"<tt>if (A &lt; B &amp;&amp; A &lt; B)</tt>", and can turn short-circuiting
181operators into the strict versions when useful (such as "<tt>if (A &lt; B || A
182&gt; C)</tt>" into "<tt>if (A &lt; B | A &gt; C)</tt>"</li>
183
Chris Lattnerd4594dc2004-05-04 17:04:09 +0000[diff] [blame]184<li>LLVM now has infrastructure for (simple and sparse conditional) constant
185propagation of function calls. It currently supports a few math library
186functions like sqrt/sin/cos/etc.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]187</ol>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]188
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]189
190<!--=========================================================================-->
191<div class="doc_subsubsection">
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]192<a name="bugfix">In this release, the following bugs in the previous release
193were fixed:</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]194</div>
195
196<p>Bugs in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]197
198<ol>
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]199<li><a href="http://llvm.cs.uiuc.edu/PR306">[loopsimplify] Loop simplify
200incorrectly updates dominator information</a></li>
201<li><a href="http://llvm.cs.uiuc.edu/PR310">[tailduplicate] DemoteRegToStack
202breaks SSA form</a></li>
203<li><a href="http://llvm.cs.uiuc.edu/PR313">[X86] JIT miscompiles unsigned short
204to floating point cast</a></li>
Chris Lattnerd4594dc2004-05-04 17:04:09 +0000[diff] [blame]205<li><a href="http://llvm.cs.uiuc.edu/PR332">[adce] Crash handling unreachable code that unwinds</a></li>
Brian Gaeke43be3112004-05-04 21:22:57 +0000[diff] [blame^]206<li><a href="http://llvm.cs.uiuc.edu/PR333">[sparc] LLC can't emit 2 functions of
207the same name, both having constant pools</a></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]208</ol>
209
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]210<p>Bugs in the C/C++ front-end:</p>
211
212<ol>
Chris Lattner6df29c62004-04-21 18:52:06 +0000[diff] [blame]213<li><a href="http://llvm.cs.uiuc.edu/PR326">[llvmgcc] Crash on use of undeclared enum type</a></li></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]214</ol>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]215
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]216</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]217
218<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]219<div class="doc_section">
220 <a name="portability">Portability and Supported Platforms</a>
221</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]222<!-- *********************************************************************** -->
223
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]224<div class="doc_text">
225
226<p>LLVM has been extensively tested on Intel and AMD machines running Red
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]227Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations
228running Solaris 8. Additionally, LLVM works on Mac OS X 10.3 and above, but
229only with the C backend or interpreter (no native backend for the PowerPC is
230available yet). The core LLVM infrastructure uses "autoconf" for portability,
231so hopefully we work on more platforms than that. However, it is likely that we
232missed something and that minor porting is required to get LLVM to work on new
233platforms. We welcome portability patches and error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]234
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]235</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]236
Brian Gaeke21a710a2004-04-20 18:18:46 +0000[diff] [blame]237<!--=========================================================================-->
238<div class="doc_subsection">
239In this release, the following portability problems were fixed:
240</div>
241
242<ol>
243<li><a href="http://llvm.cs.uiuc.edu/PR304">warnings compiling Stacker compiler on Mac OS X</a></li>
Chris Lattnerd4594dc2004-05-04 17:04:09 +0000[diff] [blame]244<li><a href="http://llvm.cs.uiuc.edu/PR308">Archive file reader doesn't understand abbreviated names in headers</a></li>
Brian Gaeke21a710a2004-04-20 18:18:46 +0000[diff] [blame]245</ol>
246
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]247<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]248<div class="doc_section">
249 <a name="knownproblems">Known Problems</a>
250</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]251<!-- *********************************************************************** -->
252
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]253<div class="doc_text">
254
255<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]256component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]257sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]258href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]259there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]260
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]261</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]262
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]263<!-- ======================================================================= -->
264<div class="doc_subsection">
265 <a name="experimental">Experimental features included with this release</a>
266</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]267
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]268<div class="doc_text">
269
270<p>
271The following components of this LLVM release are either untested, known to be
272broken or unreliable, or are in early development. These components should not
273be relied on, and bugs should not be filed against them, but they may be useful
274to some people. In particular, if you would like to work on one of these
275components, please contact us on the llvmdev list.
276</p>
277
278<ul>
279<li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
280 -ipmodref, -sortstructs, -swapstructs, -cee</tt></li>
281
282<li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
283 it should) and not thoroughly tested.</li>
284<li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
285<li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
286</ul>
287
288</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]289
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]290<!-- ======================================================================= -->
291<div class="doc_subsection">
292 <a name="core">Known problems with the LLVM Core</a>
293</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]294
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]295<div class="doc_text">
296
297<ul>
298
299<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
300work.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]301
302<li>The JIT does not use mutexes to protect its internal data structures. As
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]303such, execution of a threaded program could cause these data structures to be
304corrupted.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]305
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]306<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]307
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]308<li>Linking in static archive files (.a files) is very slow (there is no symbol
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]309table in the archive).</li>
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]310
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]311<li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
312objects/archives in the order specified on the command line.</a></li>
Chris Lattner2e6fcaf2004-02-15 23:09:07 +0000[diff] [blame]313
314<li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
John Criswelld46c6962004-03-12 21:29:42 +0000[diff] [blame]315values live across a setjmp as volatile</a>. This missing feature only affects
Chris Lattner2e6fcaf2004-02-15 23:09:07 +0000[diff] [blame]316targets whose setjmp/longjmp libraries do not save and restore the entire
317register file.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]318</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]319</div>
320
321<!-- ======================================================================= -->
322<div class="doc_subsection">
323 <a name="c-fe">Known problems with the C front-end</a>
324</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]325
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]326<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]327<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]328
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]329<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]330<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]331<li>C99 Variable sized arrays do not release stack memory when they go out of
332 scope. Thus, the following program may run out of stack space:
333<pre>
334 for (i = 0; i != 1000000; ++i) {
335 int X[n];
336 foo(X);
337 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]338</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]339
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]340<li>
341Initialization of global union variables can only be done
342<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
343union member</a>.
344</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]345
Misha Brukmana7aadf12004-04-19 02:56:49 +0000[diff] [blame]346<li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
347external function is re-declared as static</a></li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]348
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]349</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]350</div>
351
352<!-- _______________________________________________________________________ -->
353<div class="doc_subsubsection">
354 Notes
355</div>
356
357<div class="doc_text">
358
359<ul>
360
361<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]362
363<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]364support for floating point data types of any size other than 32 and 64
365bits.</li>
366
367<li>The following Unix system functionality has not been tested and may not
368work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]369 <ol>
370 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
371 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
372 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
373 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
374 - These functions have not been tested.
375 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]376
377<li>Although many GCC extensions are supported, some are not. In particular,
378 the following extensions are known to <b>not be</b> supported:
379 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]380 <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 +0000[diff] [blame]381 <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>
382 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
383 <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>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]384 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]385 <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>
386 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]387 <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>
388 <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>
389 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
390 <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 +0000[diff] [blame]391 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]392
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]393 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]394 attribute means that the LLVM compiler ignores the presence of the attribute,
395 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]396 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]397 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]398
399 <ol>
400 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
401 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]402 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]403
404 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]405
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]406 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]407 return.<br>
408
409 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
410 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
411 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
412
413 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
414 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
415 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
416
417 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
418 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
419 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]420
421 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
422 Specifying attributes of variables.<br>
423 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
424 <tt>deprecated</tt>, <tt>transparent_union</tt>,
425 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]426
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]427 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
428 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
429 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]430 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]431
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]432 <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 +0000[diff] [blame]433 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]434 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]435
436 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
437 all target specific attributes.</li>
438
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]439 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
440 Other built-in functions.<br>
441 We support all builtins which have a C language equivalent (e.g.,
442 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
443 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]444 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]445
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]446 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]447
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]448 <p>The following extensions <b>are</b> known to be supported:</p>
449
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]450 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]451 <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 +0000[diff] [blame]452 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
453 <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>
454 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
456 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
458 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
459 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
460 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
461 <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>
462 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
463 <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 +0000[diff] [blame]464 <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 +0000[diff] [blame]465 <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 +0000[diff] [blame]466 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
467or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]468 <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 +0000[diff] [blame]469 <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 +0000[diff] [blame]470 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
471 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
472 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
473 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
474 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
475 <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>
476 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
477 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
478 <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>
479 <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>
480 <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 +0000[diff] [blame]481 <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 +0000[diff] [blame]482 <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>
483 <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 +0000[diff] [blame]484 </ol></li>
485
486</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]487
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]488<p>If you run into GCC extensions which have not been included in any of these
489lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]490
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]491</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]492
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]493<!-- ======================================================================= -->
494<div class="doc_subsection">
495 <a name="c++-fe">Known problems with the C++ front-end</a>
496</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]497
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]498<div class="doc_text">
499
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]500<p>For this release, the C++ front-end is considered to be fully functional but
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]501has not been tested as thoroughly as the C front-end. It has been tested and
502works for a number of non-trivial programs, but there may be lurking bugs.
503Please report any bugs or problems.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]504
505</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]506
507<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]508<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]509
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]510<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]511
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]512<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]513<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]514 front-end</a>.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]515</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]516</div>
517
518<!-- _______________________________________________________________________ -->
519<div class="doc_subsubsection">
520 Notes
521</div>
522
523<div class="doc_text">
524
525<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]526
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]527<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
528parser is significantly more standards compliant (and picky) than prior GCC
529versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]530href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]531
532<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]533 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]534 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]535 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]536 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]537
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]538<li>The LLVM C++ front-end follows the <a
539 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
540 This document, which is not Itanium specific, specifies a standard for name
541 mangling, class layout, v-table layout, RTTI formats, and other C++
542 representation issues. Because we use this API, code generated by the LLVM
543 compilers should be binary compatible with machine code generated by other
544 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
545 <i>However</i>, the exception handling mechanism used by LLVM is very
546 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]547 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]548
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]549</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]550
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]551</div>
552
553<!-- ======================================================================= -->
554<div class="doc_subsection">
555 <a name="x86-be">Known problems with the X86 back-end</a>
556</div>
557
558<div class="doc_text">
559
560<ul>
Chris Lattnerde4afdc2004-02-08 22:23:33 +0000[diff] [blame]561<li>None so far.
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]562</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]563
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]564</div>
565
566<!-- ======================================================================= -->
567<div class="doc_subsection">
568 <a name="sparc-be">Known problems with the Sparc back-end</a>
569</div>
570
571<div class="doc_text">
572
573<ul>
Chris Lattner6a39aa52004-03-19 19:22:28 +0000[diff] [blame]574<li>There are several programs in the LLVM testsuite that the Sparc code generator is known to miscompile.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]575</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]576
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]577</div>
578
579<!-- ======================================================================= -->
580<div class="doc_subsection">
581 <a name="c-be">Known problems with the C back-end</a>
582</div>
583
584<div class="doc_text">
585
586<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]587
588<li>The C back-end produces code that violates the ANSI C Type-Based Alias
589Analysis rules. As such, special options may be necessary to compile the code
590(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]591problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]592
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]593<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]594cannot include special floating point numbers like Not-A-Number or
595Infinity.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]596
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]597<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]598supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]599frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]600
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]601</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]602
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]603</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]604
605<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]606<div class="doc_section">
607 <a name="additionalinfo">Additional Information</a>
608</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]609<!-- *********************************************************************** -->
610
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]611<div class="doc_text">
612
613<p>A wide variety of additional information is available on the LLVM web page,
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]614including mailing lists and publications describing algorithms and components
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]615implemented in LLVM. The web page also contains versions of the API
616documentation which is up-to-date with the CVS version of the source code. You
617can access versions of these documents specific to this release by going into
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]618the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]619
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]620<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]621us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
622lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]623
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]624</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]625
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]628<hr>
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Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]635 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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