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Chris Lattner2974b5b2004-04-01 00:41:31 +00006 <title>LLVM 1.3 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +00007</head>
8<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +00009
Chris Lattner2974b5b2004-04-01 00:41:31 +000010<div class="doc_title">LLVM 1.3 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000011
12<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000013 <li><a href="#intro">Introduction</a></li>
14 <li><a href="#whatsnew">What's New?</a></li>
15 <li><a href="#portability">Portability and Supported Platforms</a></li>
16 <li><a href="#install-instructions">Installation Instructions</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000017 <li><a href="#knownproblems">Known Problems</a>
18 <ul>
Chris Lattner2974b5b2004-04-01 00:41:31 +000019 <li><a href="#experimental">Experimental features included in this
20 release</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +000021 <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 +000027 </ul></li>
28 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000029</ol>
30
Misha Brukmane0c891c2003-11-22 01:00:11 +000031<div class="doc_text">
John Criswelld000e1d2003-12-18 16:43:17 +000032 <p><b>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM team</a></b><p>
Misha Brukman500bc302003-11-22 00:38:41 +000033</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000034
35<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000036<div class="doc_section">
37 <a name="intro">Introduction</a>
38</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000039<!-- *********************************************************************** -->
40
Misha Brukman500bc302003-11-22 00:38:41 +000041<div class="doc_text">
42
43<p>This document contains the release notes for the LLVM compiler
Chris Lattner2974b5b2004-04-01 00:41:31 +000044infrastructure, release 1.3. Here we describe the status of LLVM, including any
John Criswelld000e1d2003-12-18 16:43:17 +000045known problems and bug fixes from the previous release. The most up-to-date
Misha Brukman500bc302003-11-22 00:38:41 +000046version of this document can be found on the <a
Chris Lattner2974b5b2004-04-01 00:41:31 +000047href="http://llvm.cs.uiuc.edu/releases/1.3/">LLVM 1.3 web site</a>. If you are
John Criswelld000e1d2003-12-18 16:43:17 +000048not reading this on the LLVM web pages, you should probably go there because
Misha Brukman500bc302003-11-22 00:38:41 +000049this document may be updated after the release.</p>
Chris Lattner19092612003-10-02 16:38:05 +000050
Misha Brukman500bc302003-11-22 00:38:41 +000051<p>For more information about LLVM, including information about potentially more
Chris Lattner47ad72c2003-10-07 21:38:31 +000052current 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 +000055list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000056
Chris Lattner9e848092003-12-12 04:25:33 +000057<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 +000060href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
61
62</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000063
64<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000065<div class="doc_section">
66 <a name="whatsnew">What's New?</a>
67</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000068<!-- *********************************************************************** -->
69
Misha Brukman500bc302003-11-22 00:38:41 +000070<div class="doc_text">
71
Chris Lattnera39719f2004-02-25 16:36:51 +000072<p>
Chris Lattner2974b5b2004-04-01 00:41:31 +000073This is the fourth public release of the LLVM compiler infrastructure.
Chris Lattnerb40efb32003-12-14 05:03:43 +000074</p>
Chris Lattnera5099962003-12-06 20:22:41 +000075
Chris Lattner835104c2004-03-17 03:54:41 +000076<p>
77At this time, LLVM is known to correctly compile and run all C &amp; C++ SPEC
78CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist benchmarks. It has
79also been used to compile <b>many</b> other programs. LLVM now also works with
80a broad variety of C++ programs, though it has still received less testing than
81the C front-end.
Chris Lattnera5099962003-12-06 20:22:41 +000082</p>
83
Chris Lattnera5099962003-12-06 20:22:41 +000084<!--=========================================================================-->
85<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +000086<a name="newfeatures">This release implements the following new features:</a>
Chris Lattnera5099962003-12-06 20:22:41 +000087</div>
Chris Lattner47ad72c2003-10-07 21:38:31 +000088
89<ol>
Chris Lattner2974b5b2004-04-01 00:41:31 +000090<li>The LLVM <a href="LangRef.html#i_select"><tt>select</tt></a> instruction is
91now fully implemented and supported by all targets.</li>
Chris Lattneracd85c52004-04-06 19:48:42 +000092<li>Bugpoint can now narrow down code-generation bugs to a loop nest, where before it could only narrow them down to a function being miscompiled.</li>
Chris Lattner55ee0312003-11-19 22:05:38 +000093</ol>
Chris Lattner0ef19062003-11-08 04:28:55 +000094
Chris Lattnera5099962003-12-06 20:22:41 +000095
96<!--=========================================================================-->
97<div class="doc_subsubsection">
98In this release, the following missing features were implemented:
99</div>
Chris Lattner0ef19062003-11-08 04:28:55 +0000100
101<ol>
Chris Lattnerce8492d2004-04-05 01:43:08 +0000102<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with more than 256 elements</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000103</ol>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000104
Chris Lattnera5099962003-12-06 20:22:41 +0000105
106<!--=========================================================================-->
107<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000108<a name="qualityofimp">In this release, the following Quality of Implementation issues were fixed:</a>
Chris Lattnere29ac162003-12-20 03:42:11 +0000109</div>
110
111<ol>
Chris Lattner89c60482004-04-05 00:40:55 +0000112<li><a href="http://llvm.cs.uiuc.edu/PR305">LLVM tools will happily spew bytecode onto your terminal</a></li>
Chris Lattnere29ac162003-12-20 03:42:11 +0000113</ol>
114
115<!--=========================================================================-->
116<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000117In this release, the following build problems were fixed:
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000118</div>
119
120<ol>
Chris Lattner2974b5b2004-04-01 00:41:31 +0000121<li></li>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000122</ol>
123
124<!--=========================================================================-->
125<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000126<a name="codequality">In this release, the following Code Quality issues were fixed:</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000127</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000128
129<ol>
Chris Lattner64913402004-04-13 14:43:35 +0000130<li><a href="http://llvm.cs.uiuc.edu/PR309">[vmcore] Code quality problem due to
131long operand of getelementptr</a></li>
132
133<li>The X86 backend now generates substantially better code for 64-bit integer
134and floating point operations.</li>
135
136<li>The -inline pass no longer inlines mutually recursive functions until it
137hits the inlining threshold.</li>
138
139<li>The -inline pass no longer misses obvious inlining opportunities just
140because the callee eventually calls into an external function.</li>
141
142<li>The -simplifycfg pass can now "if convert" simple statements into the new
143<tt>select</tt> instruction.</li>
144
145<li>The -loopsimplify pass can now break <a
146href="http://llvm.cs.uiuc.edu/PR35">natural loops with multiple backedges</a>
147into multiple nested loops. This enables a variety of subsequent
148optimizations.</li>
149
150<li>The -adce pass can now eliminate calls to functions that do not not write to
151memory.</li>
152
153<li>The link-time optimizer now runs the -prune-eh pass (to remove unused
154exception handlers.</li>
155
Misha Brukman500bc302003-11-22 00:38:41 +0000156</ol>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000157
Chris Lattnera5099962003-12-06 20:22:41 +0000158
159<!--=========================================================================-->
160<div class="doc_subsubsection">
Chris Lattnera39719f2004-02-25 16:36:51 +0000161<a name="bugfix">In this release, the following bugs in the previous release were fixed:</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000162</div>
163
164<p>Bugs in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000165
166<ol>
Chris Lattner1869a462004-04-01 19:09:49 +0000167<li><a href="http://llvm.cs.uiuc.edu/PR306">[loopsimplify] Loop simplify incorrectly updates dominator information</a></li>
Chris Lattner56d0f112004-04-01 20:31:29 +0000168<li><a href="http://llvm.cs.uiuc.edu/PR310">[tailduplicate] DemoteRegToStack breaks SSA form</a></li>
Chris Lattneracd85c52004-04-06 19:48:42 +0000169<li><a href="http://llvm.cs.uiuc.edu/PR313">[X86] JIT miscompiles unsigned short to floating point cast</a></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000170</ol>
171
172
Chris Lattner56e67052004-02-09 21:22:51 +0000173
Chris Lattnera5099962003-12-06 20:22:41 +0000174<p>Bugs in the C/C++ front-end:</p>
175
176<ol>
Chris Lattner2974b5b2004-04-01 00:41:31 +0000177<li></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000178</ol>
Chris Lattner19092612003-10-02 16:38:05 +0000179
Misha Brukman500bc302003-11-22 00:38:41 +0000180</div>
Chris Lattner19092612003-10-02 16:38:05 +0000181
182<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000183<div class="doc_section">
184 <a name="portability">Portability and Supported Platforms</a>
185</div>
Chris Lattner19092612003-10-02 16:38:05 +0000186<!-- *********************************************************************** -->
187
Misha Brukman500bc302003-11-22 00:38:41 +0000188<div class="doc_text">
189
190<p>LLVM has been extensively tested on Intel and AMD machines running Red
Chris Lattnerb40efb32003-12-14 05:03:43 +0000191Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
John Criswellbb1bad52003-12-12 19:54:20 +0000192Additionally,
John Criswelld000e1d2003-12-18 16:43:17 +0000193LLVM works on Mac OS X 10.3 and above, but only with the C backend or
Chris Lattner9e848092003-12-12 04:25:33 +0000194interpreter (no native backend for the PowerPC is available yet).
Chris Lattner19092612003-10-02 16:38:05 +0000195The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
Chris Lattner3e2959e2003-11-08 05:22:09 +0000196work on more platforms than that. However, it is likely that we
John Criswelld000e1d2003-12-18 16:43:17 +0000197missed something and that minor porting is required to get LLVM to work on
Misha Brukman500bc302003-11-22 00:38:41 +0000198new platforms. We welcome portability patches and error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000199
Misha Brukman500bc302003-11-22 00:38:41 +0000200</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000201
202<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000203<div class="doc_section">
204 <a name="knownproblems">Known Problems</a>
205</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000206<!-- *********************************************************************** -->
207
Misha Brukman500bc302003-11-22 00:38:41 +0000208<div class="doc_text">
209
210<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000211component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000212sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000213href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000214there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000215
Misha Brukman500bc302003-11-22 00:38:41 +0000216</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000217
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000218<!-- ======================================================================= -->
219<div class="doc_subsection">
220 <a name="experimental">Experimental features included with this release</a>
221</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000222
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000223<div class="doc_text">
224
225<p>
226The following components of this LLVM release are either untested, known to be
227broken or unreliable, or are in early development. These components should not
228be relied on, and bugs should not be filed against them, but they may be useful
229to some people. In particular, if you would like to work on one of these
230components, please contact us on the llvmdev list.
231</p>
232
233<ul>
234<li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
235 -ipmodref, -sortstructs, -swapstructs, -cee</tt></li>
236
237<li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
238 it should) and not thoroughly tested.</li>
239<li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
240<li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
241</ul>
242
243</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000244
Misha Brukman500bc302003-11-22 00:38:41 +0000245<!-- ======================================================================= -->
246<div class="doc_subsection">
247 <a name="core">Known problems with the LLVM Core</a>
248</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000249
Misha Brukman500bc302003-11-22 00:38:41 +0000250<div class="doc_text">
251
252<ul>
253
254<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
255work.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000256
257<li>The JIT does not use mutexes to protect its internal data structures. As
Misha Brukman500bc302003-11-22 00:38:41 +0000258such, execution of a threaded program could cause these data structures to be
259corrupted.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000260
Misha Brukman500bc302003-11-22 00:38:41 +0000261<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000262
Chris Lattnere84843b2003-10-20 19:05:03 +0000263<li>Linking in static archive files (.a files) is very slow (there is no symbol
Misha Brukman500bc302003-11-22 00:38:41 +0000264table in the archive).</li>
Chris Lattner2855ecd2003-11-04 20:06:53 +0000265
Chris Lattner2e6fcaf2004-02-15 23:09:07 +0000266<li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link objects/archives in the order specified on the command line.</a></li>
267
268<li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
John Criswelld46c6962004-03-12 21:29:42 +0000269values live across a setjmp as volatile</a>. This missing feature only affects
Chris Lattner2e6fcaf2004-02-15 23:09:07 +0000270targets whose setjmp/longjmp libraries do not save and restore the entire
271register file.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000272</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000273</div>
274
275<!-- ======================================================================= -->
276<div class="doc_subsection">
277 <a name="c-fe">Known problems with the C front-end</a>
278</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000279
Chris Lattner79c3fe12003-10-02 04:57:28 +0000280<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000281<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000282
Misha Brukman500bc302003-11-22 00:38:41 +0000283<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000284<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000285<li>C99 Variable sized arrays do not release stack memory when they go out of
286 scope. Thus, the following program may run out of stack space:
287<pre>
288 for (i = 0; i != 1000000; ++i) {
289 int X[n];
290 foo(X);
291 }
Misha Brukman500bc302003-11-22 00:38:41 +0000292</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000293
John Criswelld000e1d2003-12-18 16:43:17 +0000294<li>
295Initialization of global union variables can only be done
296<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
297union member</a>.
298</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000299
300<li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly external function is re-declared as static</a></li>
301
John Criswelld000e1d2003-12-18 16:43:17 +0000302</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000303</div>
304
305<!-- _______________________________________________________________________ -->
306<div class="doc_subsubsection">
307 Notes
308</div>
309
310<div class="doc_text">
311
312<ul>
313
314<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000315
316<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000317support for floating point data types of any size other than 32 and 64
318bits.</li>
319
320<li>The following Unix system functionality has not been tested and may not
321work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000322 <ol>
323 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
324 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
325 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
326 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
327 - These functions have not been tested.
328 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000329
330<li>Although many GCC extensions are supported, some are not. In particular,
331 the following extensions are known to <b>not be</b> supported:
332 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000333 <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 +0000334 <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>
335 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
336 <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 +0000337 <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 +0000338 <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>
339 <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 +0000340 <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>
341 <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>
342 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
343 <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 +0000344 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000345
Misha Brukman500bc302003-11-22 00:38:41 +0000346 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000347 attribute means that the LLVM compiler ignores the presence of the attribute,
348 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000349 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000350 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000351
352 <ol>
353 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
354 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000355 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000356
357 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000358
John Criswelld000e1d2003-12-18 16:43:17 +0000359 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000360 return.<br>
361
362 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
363 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
364 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
365
366 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
367 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
368 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
369
370 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
371 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
372 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000373
374 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
375 Specifying attributes of variables.<br>
376 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
377 <tt>deprecated</tt>, <tt>transparent_union</tt>,
378 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000379
Chris Lattner79c3fe12003-10-02 04:57:28 +0000380 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
381 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
382 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000383 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000384
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000385 <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 +0000386 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000387 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000388
389 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
390 all target specific attributes.</li>
391
Chris Lattner79c3fe12003-10-02 04:57:28 +0000392 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
393 Other built-in functions.<br>
394 We support all builtins which have a C language equivalent (e.g.,
395 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
396 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000397 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000398
Misha Brukman500bc302003-11-22 00:38:41 +0000399 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000400
Misha Brukman500bc302003-11-22 00:38:41 +0000401 <p>The following extensions <b>are</b> known to be supported:</p>
402
Chris Lattner79c3fe12003-10-02 04:57:28 +0000403 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000404 <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 +0000405 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
406 <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>
407 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
408 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
409 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
410 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
411 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
412 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
413 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
414 <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>
415 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
416 <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 +0000417 <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 +0000418 <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 +0000419 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
420or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000421 <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 +0000422 <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 +0000423 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
424 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
425 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
426 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
427 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
428 <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>
429 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
430 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
431 <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>
432 <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>
433 <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 +0000434 <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 +0000435 <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>
436 <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 +0000437 </ol></li>
438
439</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000440
Misha Brukman500bc302003-11-22 00:38:41 +0000441<p>If you run into GCC extensions which have not been included in any of these
442lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000443
Misha Brukman500bc302003-11-22 00:38:41 +0000444</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000445
Misha Brukman500bc302003-11-22 00:38:41 +0000446<!-- ======================================================================= -->
447<div class="doc_subsection">
448 <a name="c++-fe">Known problems with the C++ front-end</a>
449</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000450
Misha Brukman500bc302003-11-22 00:38:41 +0000451<div class="doc_text">
452
John Criswelld000e1d2003-12-18 16:43:17 +0000453<p>For this release, the C++ front-end is considered to be fully functional but
Chris Lattner9e848092003-12-12 04:25:33 +0000454has not been tested as thoroughly as the C front-end. It has been tested and
455works for a number of non-trivial programs, but there may be lurking bugs.
456Please report any bugs or problems.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000457
458</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000459
460<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000461<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000462
Misha Brukman500bc302003-11-22 00:38:41 +0000463<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000464
Misha Brukman500bc302003-11-22 00:38:41 +0000465<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000466<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000467 front-end</a>.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000468</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000469</div>
470
471<!-- _______________________________________________________________________ -->
472<div class="doc_subsubsection">
473 Notes
474</div>
475
476<div class="doc_text">
477
478<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000479
Chris Lattner79c3fe12003-10-02 04:57:28 +0000480<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
481parser is significantly more standards compliant (and picky) than prior GCC
482versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000483href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000484
485<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000486 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000487 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000488 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000489 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000490
Chris Lattner19092612003-10-02 16:38:05 +0000491<li>The LLVM C++ front-end follows the <a
492 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
493 This document, which is not Itanium specific, specifies a standard for name
494 mangling, class layout, v-table layout, RTTI formats, and other C++
495 representation issues. Because we use this API, code generated by the LLVM
496 compilers should be binary compatible with machine code generated by other
497 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
498 <i>However</i>, the exception handling mechanism used by LLVM is very
499 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000500 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000501
Misha Brukman500bc302003-11-22 00:38:41 +0000502</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000503
Misha Brukman500bc302003-11-22 00:38:41 +0000504</div>
505
506<!-- ======================================================================= -->
507<div class="doc_subsection">
508 <a name="x86-be">Known problems with the X86 back-end</a>
509</div>
510
511<div class="doc_text">
512
513<ul>
Chris Lattnerde4afdc2004-02-08 22:23:33 +0000514<li>None so far.
Misha Brukman500bc302003-11-22 00:38:41 +0000515</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000516
Misha Brukman500bc302003-11-22 00:38:41 +0000517</div>
518
519<!-- ======================================================================= -->
520<div class="doc_subsection">
521 <a name="sparc-be">Known problems with the Sparc back-end</a>
522</div>
523
524<div class="doc_text">
525
526<ul>
Chris Lattner6a39aa52004-03-19 19:22:28 +0000527<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 +0000528</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000529
Misha Brukman500bc302003-11-22 00:38:41 +0000530</div>
531
532<!-- ======================================================================= -->
533<div class="doc_subsection">
534 <a name="c-be">Known problems with the C back-end</a>
535</div>
536
537<div class="doc_text">
538
539<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000540
541<li>The C back-end produces code that violates the ANSI C Type-Based Alias
542Analysis rules. As such, special options may be necessary to compile the code
543(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000544problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000545
Chris Lattnere84843b2003-10-20 19:05:03 +0000546<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000547cannot include special floating point numbers like Not-A-Number or
548Infinity.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000549
Chris Lattner2855ecd2003-11-04 20:06:53 +0000550<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000551supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000552frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000553
Misha Brukman500bc302003-11-22 00:38:41 +0000554</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000555
Misha Brukman500bc302003-11-22 00:38:41 +0000556</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000557
558<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000559<div class="doc_section">
560 <a name="additionalinfo">Additional Information</a>
561</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000562<!-- *********************************************************************** -->
563
Misha Brukman500bc302003-11-22 00:38:41 +0000564<div class="doc_text">
565
566<p>A wide variety of additional information is available on the LLVM web page,
John Criswelld000e1d2003-12-18 16:43:17 +0000567including mailing lists and publications describing algorithms and components
Chris Lattner79c3fe12003-10-02 04:57:28 +0000568implemented in LLVM. The web page also contains versions of the API
569documentation which is up-to-date with the CVS version of the source code. You
570can access versions of these documents specific to this release by going into
Misha Brukman500bc302003-11-22 00:38:41 +0000571the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000572
Misha Brukman500bc302003-11-22 00:38:41 +0000573<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner5eccca42003-12-12 21:22:16 +0000574us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
575lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000576
Misha Brukman500bc302003-11-22 00:38:41 +0000577</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000578
579<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000580
Misha Brukman500bc302003-11-22 00:38:41 +0000581<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000582<address>
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587
Misha Brukmane0c891c2003-11-22 01:00:11 +0000588 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000589 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000590</address>
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