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Chris Lattnerb40efb32003-12-14 05:03:43 +00006 <title>LLVM 1.2 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +00007</head>
8<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +00009
Misha Brukman500bc302003-11-22 00:38:41 +000010<div class="doc_title">
Chris Lattnerb40efb32003-12-14 05:03:43 +000011 LLVM 1.2 Release Notes
Misha Brukman500bc302003-11-22 00:38:41 +000012</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000013
14<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000015 <li><a href="#intro">Introduction</a></li>
16 <li><a href="#whatsnew">What's New?</a></li>
17 <li><a href="#portability">Portability and Supported Platforms</a></li>
18 <li><a href="#install-instructions">Installation Instructions</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000019 <li><a href="#knownproblems">Known Problems</a>
20 <ul>
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 Lattnerb40efb32003-12-14 05:03:43 +000044infrastructure, release 1.2. 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 Lattnerb40efb32003-12-14 05:03:43 +000047href="http://llvm.cs.uiuc.edu/releases/1.2/">LLVM 1.2 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
John Criswelld000e1d2003-12-18 16:43:17 +000072<p>This is the third public release of the LLVM compiler infrastructure.
Chris Lattnerb40efb32003-12-14 05:03:43 +000073</p>
Chris Lattnera5099962003-12-06 20:22:41 +000074
Chris Lattner1124e2c2003-12-12 21:33:08 +000075<p>At this time, LLVM is known to correctly compile and run all non-unwinding C
76&amp; C++ SPEC CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist
77benchmarks. It has also been used to compile <b>many</b> other programs. LLVM
78now also works with a broad variety of C++ programs, though it has still
79received much less testing than the C front-end.
Chris Lattnera5099962003-12-06 20:22:41 +000080</p>
81
82<p>
John Criswelld000e1d2003-12-18 16:43:17 +000083The LLVM native code generators are very stable but do not currently support
Chris Lattner1124e2c2003-12-12 21:33:08 +000084unwinding (exception throwing or <tt>longjmp</tt>ing), which prevent them from
85working with programs like the <tt>253.perlbmk</tt> in SPEC CPU2000. The C
John Criswelld000e1d2003-12-18 16:43:17 +000086backend and the rest of LLVM supports these programs, so you can
Chris Lattner1124e2c2003-12-12 21:33:08 +000087still use LLVM with them. Support for unwinding will be added in a future
88release.
Chris Lattnera5099962003-12-06 20:22:41 +000089</p>
90
91
92<!--=========================================================================-->
93<div class="doc_subsubsection">
94This release implements the following new features:
95</div>
Chris Lattner47ad72c2003-10-07 21:38:31 +000096
97<ol>
Chris Lattnerb40efb32003-12-14 05:03:43 +000098<li></li>
99<li></li>
Chris Lattner55ee0312003-11-19 22:05:38 +0000100</ol>
Chris Lattner0ef19062003-11-08 04:28:55 +0000101
Chris Lattnera5099962003-12-06 20:22:41 +0000102
103<!--=========================================================================-->
104<div class="doc_subsubsection">
105In this release, the following missing features were implemented:
106</div>
Chris Lattner0ef19062003-11-08 04:28:55 +0000107
108<ol>
Chris Lattnerb40efb32003-12-14 05:03:43 +0000109<li></li>
110<li></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000111</ol>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000112
Chris Lattnera5099962003-12-06 20:22:41 +0000113
114<!--=========================================================================-->
115<div class="doc_subsubsection">
116In this release, the following Quality of Implementation issues were
117fixed:
118</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000119
120<ol>
Chris Lattner0ef19062003-11-08 04:28:55 +0000121
Chris Lattnerb40efb32003-12-14 05:03:43 +0000122<li></li>
Chris Lattner0ef19062003-11-08 04:28:55 +0000123
Chris Lattnerb40efb32003-12-14 05:03:43 +0000124<li></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000125</ol>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000126
Chris Lattnera5099962003-12-06 20:22:41 +0000127
128<!--=========================================================================-->
129<div class="doc_subsubsection">
130In this release, the following bugs in the previous release were fixed:
131</div>
132
133<p>Bugs in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000134
135<ol>
Misha Brukmanad643852003-12-15 22:48:12 +0000136<li><a href="http://llvm.cs.uiuc.edu/PR179">[licm] LICM promotes volatile memory
137locations to registers</a></li>
Chris Lattner5b7142a2003-12-18 08:16:25 +0000138<li><a href="http://llvm.cs.uiuc.edu/PR191">[licm] Memory read after free causes
139infrequent crash</a></li>
Chris Lattnerb40efb32003-12-14 05:03:43 +0000140
Chris Lattnera5099962003-12-06 20:22:41 +0000141</ol>
142
143
144<p>Bugs in the C/C++ front-end:</p>
145
146<ol>
Misha Brukmanad643852003-12-15 22:48:12 +0000147<li><a href="http://llvm.cs.uiuc.edu/PR186">Need weak linkage on memory
148management functions in libc runtime to allow them to be overriden</a></li>
Chris Lattnerb40efb32003-12-14 05:03:43 +0000149<li></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000150</ol>
Chris Lattner19092612003-10-02 16:38:05 +0000151
Misha Brukman500bc302003-11-22 00:38:41 +0000152</div>
Chris Lattner19092612003-10-02 16:38:05 +0000153
154<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000155<div class="doc_section">
156 <a name="portability">Portability and Supported Platforms</a>
157</div>
Chris Lattner19092612003-10-02 16:38:05 +0000158<!-- *********************************************************************** -->
159
Misha Brukman500bc302003-11-22 00:38:41 +0000160<div class="doc_text">
161
162<p>LLVM has been extensively tested on Intel and AMD machines running Red
Chris Lattnerb40efb32003-12-14 05:03:43 +0000163Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
John Criswellbb1bad52003-12-12 19:54:20 +0000164Additionally,
John Criswelld000e1d2003-12-18 16:43:17 +0000165LLVM works on Mac OS X 10.3 and above, but only with the C backend or
Chris Lattner9e848092003-12-12 04:25:33 +0000166interpreter (no native backend for the PowerPC is available yet).
Chris Lattner19092612003-10-02 16:38:05 +0000167The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
Chris Lattner3e2959e2003-11-08 05:22:09 +0000168work on more platforms than that. However, it is likely that we
John Criswelld000e1d2003-12-18 16:43:17 +0000169missed something and that minor porting is required to get LLVM to work on
Misha Brukman500bc302003-11-22 00:38:41 +0000170new platforms. We welcome portability patches and error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000171
Misha Brukman500bc302003-11-22 00:38:41 +0000172</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000173
174<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000175<div class="doc_section">
176 <a name="knownproblems">Known Problems</a>
177</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000178<!-- *********************************************************************** -->
179
Misha Brukman500bc302003-11-22 00:38:41 +0000180<div class="doc_text">
181
182<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000183component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000184sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000185href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000186there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000187
Misha Brukman500bc302003-11-22 00:38:41 +0000188</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000189
190<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000191<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000192</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000193-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000194
195
Misha Brukman500bc302003-11-22 00:38:41 +0000196<!-- ======================================================================= -->
197<div class="doc_subsection">
198 <a name="core">Known problems with the LLVM Core</a>
199</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000200
Misha Brukman500bc302003-11-22 00:38:41 +0000201<div class="doc_text">
202
203<ul>
204
205<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
206work.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000207
208<li>The JIT does not use mutexes to protect its internal data structures. As
Misha Brukman500bc302003-11-22 00:38:41 +0000209such, execution of a threaded program could cause these data structures to be
210corrupted.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000211
Misha Brukman500bc302003-11-22 00:38:41 +0000212<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000213
Chris Lattnere84843b2003-10-20 19:05:03 +0000214<li>Linking in static archive files (.a files) is very slow (there is no symbol
Misha Brukman500bc302003-11-22 00:38:41 +0000215table in the archive).</li>
Chris Lattner2855ecd2003-11-04 20:06:53 +0000216
Chris Lattner2855ecd2003-11-04 20:06:53 +0000217<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
Misha Brukman500bc302003-11-22 00:38:41 +0000218more than 256 elements</a>.</li>
219
John Criswelld000e1d2003-12-18 16:43:17 +0000220<li>
221The gccld program
222<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=139">
223does not link objects/archives in the order specified on the command line.
224</a>
225</li>
226
227<li>
228<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=174">
229Tail duplication does not update SSA form correctly.
230</a>
231</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000232</ul>
233
234</div>
235
236<!-- ======================================================================= -->
237<div class="doc_subsection">
238 <a name="c-fe">Known problems with the C front-end</a>
239</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000240
Chris Lattner79c3fe12003-10-02 04:57:28 +0000241<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000242<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000243
Misha Brukman500bc302003-11-22 00:38:41 +0000244<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000245<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000246<li>C99 Variable sized arrays do not release stack memory when they go out of
247 scope. Thus, the following program may run out of stack space:
248<pre>
249 for (i = 0; i != 1000000; ++i) {
250 int X[n];
251 foo(X);
252 }
Misha Brukman500bc302003-11-22 00:38:41 +0000253</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000254
John Criswelld000e1d2003-12-18 16:43:17 +0000255<li>
256Initialization of global union variables can only be done
257<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
258union member</a>.
259</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000260
John Criswelld000e1d2003-12-18 16:43:17 +0000261<li>
262<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=182">
263Functions marked "extern inline" are not compiled into LLVM with linkonce
264linkage.
265</a>
266</li>
267
268
269<li>
270The memory management functions in the libc runtime
271<a href="http://llvm.cs.uiuc.edu/PR186">need weak linkage so that they can be
272overridden.
273</a>
274</li>
275</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000276</div>
277
278<!-- _______________________________________________________________________ -->
279<div class="doc_subsubsection">
280 Notes
281</div>
282
283<div class="doc_text">
284
285<ul>
286
287<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000288
289<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000290support for floating point data types of any size other than 32 and 64
291bits.</li>
292
293<li>The following Unix system functionality has not been tested and may not
294work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000295 <ol>
296 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
297 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
298 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
299 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
300 - These functions have not been tested.
301 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000302
303<li>Although many GCC extensions are supported, some are not. In particular,
304 the following extensions are known to <b>not be</b> supported:
305 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000306 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000307 <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 +0000308 <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>
309 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
310 <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 +0000311 <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 +0000312 <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>
313 <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>
314 <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>
315 <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>
316 <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>
317 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
318 <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 +0000319 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000320
Misha Brukman500bc302003-11-22 00:38:41 +0000321 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000322 attribute means that the LLVM compiler ignores the presence of the attribute,
323 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000324 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000325 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000326
327 <ol>
328 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
329 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000330 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000331
332 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000333
John Criswelld000e1d2003-12-18 16:43:17 +0000334 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000335 return.<br>
336
337 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
338 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
339 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
340
341 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
342 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
343 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
344
345 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
346 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
347 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000348
349 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
350 Specifying attributes of variables.<br>
351 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
352 <tt>deprecated</tt>, <tt>transparent_union</tt>,
353 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000354
Chris Lattner79c3fe12003-10-02 04:57:28 +0000355 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
356 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
357 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000358 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000359
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000360 <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 +0000361 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000362 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000363
364 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
365 all target specific attributes.</li>
366
Chris Lattner79c3fe12003-10-02 04:57:28 +0000367 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
368 Other built-in functions.<br>
369 We support all builtins which have a C language equivalent (e.g.,
370 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
371 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000372 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000373
Misha Brukman500bc302003-11-22 00:38:41 +0000374 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000375
Misha Brukman500bc302003-11-22 00:38:41 +0000376 <p>The following extensions <b>are</b> known to be supported:</p>
377
Chris Lattner79c3fe12003-10-02 04:57:28 +0000378 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000379 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
380 <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>
381 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
382 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
383 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
384 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
385 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
386 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
387 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
388 <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>
389 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
390 <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 +0000391 <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 +0000392 <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 +0000393 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
394or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000395 <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 +0000396 <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 +0000397 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
398 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
399 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
400 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
401 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
402 <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>
403 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
404 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
405 <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>
406 <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>
407 <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>
408 <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>
409 <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 +0000410 </ol></li>
411
412</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000413
Misha Brukman500bc302003-11-22 00:38:41 +0000414<p>If you run into GCC extensions which have not been included in any of these
415lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000416
Misha Brukman500bc302003-11-22 00:38:41 +0000417</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000418
Misha Brukman500bc302003-11-22 00:38:41 +0000419<!-- ======================================================================= -->
420<div class="doc_subsection">
421 <a name="c++-fe">Known problems with the C++ front-end</a>
422</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000423
Misha Brukman500bc302003-11-22 00:38:41 +0000424<div class="doc_text">
425
John Criswelld000e1d2003-12-18 16:43:17 +0000426<p>For this release, the C++ front-end is considered to be fully functional but
Chris Lattner9e848092003-12-12 04:25:33 +0000427has not been tested as thoroughly as the C front-end. It has been tested and
428works for a number of non-trivial programs, but there may be lurking bugs.
429Please report any bugs or problems.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000430
431</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000432
433<!-- _______________________________________________________________________ -->
Misha Brukman500bc302003-11-22 00:38:41 +0000434<div class="doc_subsubsection">
435 Bugs
436</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000437
Misha Brukman500bc302003-11-22 00:38:41 +0000438<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000439
Misha Brukman500bc302003-11-22 00:38:41 +0000440<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000441<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000442 front-end</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000443
John Criswelld000e1d2003-12-18 16:43:17 +0000444<li>
445<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=137">
446Code is generated for empty classes.
447</a>
448</li>
449</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000450</div>
451
452<!-- _______________________________________________________________________ -->
453<div class="doc_subsubsection">
454 Notes
455</div>
456
457<div class="doc_text">
458
459<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000460
Chris Lattner79c3fe12003-10-02 04:57:28 +0000461<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
462parser is significantly more standards compliant (and picky) than prior GCC
463versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000464href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000465
466<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000467 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000468 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000469 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000470 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000471
Chris Lattner19092612003-10-02 16:38:05 +0000472<li>The LLVM C++ front-end follows the <a
473 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
474 This document, which is not Itanium specific, specifies a standard for name
475 mangling, class layout, v-table layout, RTTI formats, and other C++
476 representation issues. Because we use this API, code generated by the LLVM
477 compilers should be binary compatible with machine code generated by other
478 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
479 <i>However</i>, the exception handling mechanism used by LLVM is very
480 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000481 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000482
Misha Brukman500bc302003-11-22 00:38:41 +0000483</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000484
Misha Brukman500bc302003-11-22 00:38:41 +0000485</div>
486
487<!-- ======================================================================= -->
488<div class="doc_subsection">
489 <a name="x86-be">Known problems with the X86 back-end</a>
490</div>
491
492<div class="doc_text">
493
494<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000495
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000496<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000497href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000498support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
Misha Brukman500bc302003-11-22 00:38:41 +0000499or calls the C <tt>longjmp</tt> function will abort.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000500
Misha Brukman500bc302003-11-22 00:38:41 +0000501</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000502
Misha Brukman500bc302003-11-22 00:38:41 +0000503</div>
504
505<!-- ======================================================================= -->
506<div class="doc_subsection">
507 <a name="sparc-be">Known problems with the Sparc back-end</a>
508</div>
509
510<div class="doc_text">
511
512<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000513
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000514<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000515href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000516support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
Misha Brukman500bc302003-11-22 00:38:41 +0000517or calls the C <tt>longjmp</tt> function will abort.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000518
John Criswelld000e1d2003-12-18 16:43:17 +0000519<li>
520<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=167">
521The llc program can crash on legal code.
522</a>
523</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000524</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000525
Misha Brukman500bc302003-11-22 00:38:41 +0000526</div>
527
528<!-- ======================================================================= -->
529<div class="doc_subsection">
530 <a name="c-be">Known problems with the C back-end</a>
531</div>
532
533<div class="doc_text">
534
535<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000536
537<li>The C back-end produces code that violates the ANSI C Type-Based Alias
538Analysis rules. As such, special options may be necessary to compile the code
539(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000540problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000541
Chris Lattnere84843b2003-10-20 19:05:03 +0000542<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000543cannot include special floating point numbers like Not-A-Number or
544Infinity.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000545
Chris Lattner2855ecd2003-11-04 20:06:53 +0000546<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000547supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000548frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000549
Misha Brukman500bc302003-11-22 00:38:41 +0000550</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000551
Misha Brukman500bc302003-11-22 00:38:41 +0000552</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000553
554<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000555<div class="doc_section">
556 <a name="additionalinfo">Additional Information</a>
557</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000558<!-- *********************************************************************** -->
559
Misha Brukman500bc302003-11-22 00:38:41 +0000560<div class="doc_text">
561
562<p>A wide variety of additional information is available on the LLVM web page,
John Criswelld000e1d2003-12-18 16:43:17 +0000563including mailing lists and publications describing algorithms and components
Chris Lattner79c3fe12003-10-02 04:57:28 +0000564implemented in LLVM. The web page also contains versions of the API
565documentation which is up-to-date with the CVS version of the source code. You
566can access versions of these documents specific to this release by going into
Misha Brukman500bc302003-11-22 00:38:41 +0000567the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000568
Misha Brukman500bc302003-11-22 00:38:41 +0000569<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner5eccca42003-12-12 21:22:16 +0000570us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
571lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000572
Misha Brukman500bc302003-11-22 00:38:41 +0000573</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000574
575<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000576
Misha Brukman500bc302003-11-22 00:38:41 +0000577<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000578<address>
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583
Misha Brukmane0c891c2003-11-22 01:00:11 +0000584 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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