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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">
Chris Lattnere29ac162003-12-20 03:42:11 +0000116In this release, the following Quality of Implementation issues were fixed:
117</div>
118
119<ol>
120
121<li><a href="http://llvm.cs.uiuc.edu/PR135">JIT should lazily initialize global variables</a></li>
Chris Lattneref56a192003-12-20 10:29:02 +0000122<li><a href="http://llvm.cs.uiuc.edu/PR192">[X86] X86 Backend never releases memory for machine code structures</a></li>
Chris Lattner71f0a822003-12-23 23:50:31 +0000123<li><a href="http://llvm.cs.uiuc.edu/PR196">[vmcore] OpaqueType objects memory leak</a></li>
Chris Lattner1abc87e2004-01-08 17:20:50 +0000124<li><a href="http://llvm.cs.uiuc.edu/PR182">[llvmgcc] C front-end does not compile "extern inline" into linkonce</a></li>
Chris Lattner23632f12004-01-15 17:59:29 +0000125<li><a href="http://llvm.cs.uiuc.edu/PR73">Bytecode format inconsistent</a></li>
Chris Lattnere29ac162003-12-20 03:42:11 +0000126</ol>
127
128<!--=========================================================================-->
129<div class="doc_subsubsection">
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000130In this release, the following build problems were fixed:
131</div>
132
133<ol>
134<li><a href="http://llvm.cs.uiuc.edu/PR210">[build] Makefiles break if C frontend target string has unexpected value</a></li>
135</ol>
136
137<!--=========================================================================-->
138<div class="doc_subsubsection">
Chris Lattnere29ac162003-12-20 03:42:11 +0000139In this release, the following Code Quality issues were fixed:
Chris Lattnera5099962003-12-06 20:22:41 +0000140</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000141
142<ol>
Chris Lattner9e259062003-12-19 06:31:56 +0000143<li><a href="http://llvm.cs.uiuc.edu/PR187">[loopsimplify] Many pointless phi nodes are created</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000144</ol>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000145
Chris Lattnera5099962003-12-06 20:22:41 +0000146
147<!--=========================================================================-->
148<div class="doc_subsubsection">
149In this release, the following bugs in the previous release were fixed:
150</div>
151
152<p>Bugs in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000153
154<ol>
Misha Brukmanad643852003-12-15 22:48:12 +0000155<li><a href="http://llvm.cs.uiuc.edu/PR179">[licm] LICM promotes volatile memory
156locations to registers</a></li>
Chris Lattner5b7142a2003-12-18 08:16:25 +0000157<li><a href="http://llvm.cs.uiuc.edu/PR191">[licm] Memory read after free causes
158infrequent crash</a></li>
Chris Lattner5de946f2003-12-22 04:06:24 +0000159<li><a href="http://llvm.cs.uiuc.edu/PR194">[indvars] Induction variable
160canonicalization always makes 32-bit indvars</a></li>
Chris Lattner0cbdd972003-12-22 23:56:37 +0000161<li><a href="http://llvm.cs.uiuc.edu/PR193">[constantmerge] Merging globals can
162cause use of invalid pointers!</a></li>
Chris Lattnerb40efb32003-12-14 05:03:43 +0000163
Chris Lattnera5099962003-12-06 20:22:41 +0000164</ol>
165
166
167<p>Bugs in the C/C++ front-end:</p>
168
169<ol>
Misha Brukmanad643852003-12-15 22:48:12 +0000170<li><a href="http://llvm.cs.uiuc.edu/PR186">Need weak linkage on memory
171management functions in libc runtime to allow them to be overriden</a></li>
Chris Lattner1abc87e2004-01-08 17:20:50 +0000172<li><a href="http://llvm.cs.uiuc.edu/PR202">[llvm-gcc] asserts when an extern inline function is redefined</a></li>
Chris Lattnerc43f91f2004-01-12 05:15:04 +0000173<li><a href="http://llvm.cs.uiuc.edu/PR204">[llvmg++] Dynamically initialized constants cannot be marked 'constant'</a></li>
Chris Lattnera5099962003-12-06 20:22:41 +0000174</ol>
Chris Lattner19092612003-10-02 16:38:05 +0000175
Misha Brukman500bc302003-11-22 00:38:41 +0000176</div>
Chris Lattner19092612003-10-02 16:38:05 +0000177
178<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000179<div class="doc_section">
180 <a name="portability">Portability and Supported Platforms</a>
181</div>
Chris Lattner19092612003-10-02 16:38:05 +0000182<!-- *********************************************************************** -->
183
Misha Brukman500bc302003-11-22 00:38:41 +0000184<div class="doc_text">
185
186<p>LLVM has been extensively tested on Intel and AMD machines running Red
Chris Lattnerb40efb32003-12-14 05:03:43 +0000187Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
John Criswellbb1bad52003-12-12 19:54:20 +0000188Additionally,
John Criswelld000e1d2003-12-18 16:43:17 +0000189LLVM works on Mac OS X 10.3 and above, but only with the C backend or
Chris Lattner9e848092003-12-12 04:25:33 +0000190interpreter (no native backend for the PowerPC is available yet).
Chris Lattner19092612003-10-02 16:38:05 +0000191The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
Chris Lattner3e2959e2003-11-08 05:22:09 +0000192work on more platforms than that. However, it is likely that we
John Criswelld000e1d2003-12-18 16:43:17 +0000193missed something and that minor porting is required to get LLVM to work on
Misha Brukman500bc302003-11-22 00:38:41 +0000194new platforms. We welcome portability patches and error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000195
Misha Brukman500bc302003-11-22 00:38:41 +0000196</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000197
198<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000199<div class="doc_section">
200 <a name="knownproblems">Known Problems</a>
201</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000202<!-- *********************************************************************** -->
203
Misha Brukman500bc302003-11-22 00:38:41 +0000204<div class="doc_text">
205
206<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000207component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000208sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000209href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000210there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000211
Misha Brukman500bc302003-11-22 00:38:41 +0000212</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000213
214<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000215<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000216</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000217-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000218
219
Misha Brukman500bc302003-11-22 00:38:41 +0000220<!-- ======================================================================= -->
221<div class="doc_subsection">
222 <a name="core">Known problems with the LLVM Core</a>
223</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000224
Misha Brukman500bc302003-11-22 00:38:41 +0000225<div class="doc_text">
226
227<ul>
228
229<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
230work.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000231
232<li>The JIT does not use mutexes to protect its internal data structures. As
Misha Brukman500bc302003-11-22 00:38:41 +0000233such, execution of a threaded program could cause these data structures to be
234corrupted.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000235
Misha Brukman500bc302003-11-22 00:38:41 +0000236<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000237
Chris Lattnere84843b2003-10-20 19:05:03 +0000238<li>Linking in static archive files (.a files) is very slow (there is no symbol
Misha Brukman500bc302003-11-22 00:38:41 +0000239table in the archive).</li>
Chris Lattner2855ecd2003-11-04 20:06:53 +0000240
Chris Lattner2855ecd2003-11-04 20:06:53 +0000241<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
Misha Brukman500bc302003-11-22 00:38:41 +0000242more than 256 elements</a>.</li>
243
John Criswelld000e1d2003-12-18 16:43:17 +0000244<li>
245The gccld program
246<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=139">
247does not link objects/archives in the order specified on the command line.
248</a>
249</li>
250
251<li>
252<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=174">
253Tail duplication does not update SSA form correctly.
254</a>
255</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000256</ul>
257
258</div>
259
260<!-- ======================================================================= -->
261<div class="doc_subsection">
262 <a name="c-fe">Known problems with the C front-end</a>
263</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000264
Chris Lattner79c3fe12003-10-02 04:57:28 +0000265<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000266<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000267
Misha Brukman500bc302003-11-22 00:38:41 +0000268<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000269<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000270<li>C99 Variable sized arrays do not release stack memory when they go out of
271 scope. Thus, the following program may run out of stack space:
272<pre>
273 for (i = 0; i != 1000000; ++i) {
274 int X[n];
275 foo(X);
276 }
Misha Brukman500bc302003-11-22 00:38:41 +0000277</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000278
John Criswelld000e1d2003-12-18 16:43:17 +0000279<li>
280Initialization of global union variables can only be done
281<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
282union member</a>.
283</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000284
John Criswelld000e1d2003-12-18 16:43:17 +0000285<li>
286<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=182">
287Functions marked "extern inline" are not compiled into LLVM with linkonce
288linkage.
289</a>
290</li>
291
292
293<li>
294The memory management functions in the libc runtime
295<a href="http://llvm.cs.uiuc.edu/PR186">need weak linkage so that they can be
296overridden.
297</a>
298</li>
299</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000300</div>
301
302<!-- _______________________________________________________________________ -->
303<div class="doc_subsubsection">
304 Notes
305</div>
306
307<div class="doc_text">
308
309<ul>
310
311<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000312
313<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000314support for floating point data types of any size other than 32 and 64
315bits.</li>
316
317<li>The following Unix system functionality has not been tested and may not
318work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000319 <ol>
320 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
321 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
322 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
323 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
324 - These functions have not been tested.
325 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000326
327<li>Although many GCC extensions are supported, some are not. In particular,
328 the following extensions are known to <b>not be</b> supported:
329 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000330 <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 +0000331 <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 +0000332 <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>
333 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
334 <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 +0000335 <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 +0000336 <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>
337 <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>
338 <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>
339 <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>
340 <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>
341 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
342 <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 +0000343 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000344
Misha Brukman500bc302003-11-22 00:38:41 +0000345 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000346 attribute means that the LLVM compiler ignores the presence of the attribute,
347 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000348 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000349 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000350
351 <ol>
352 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
353 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000354 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000355
356 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000357
John Criswelld000e1d2003-12-18 16:43:17 +0000358 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000359 return.<br>
360
361 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
362 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
363 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
364
365 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
366 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
367 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
368
369 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
370 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
371 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000372
373 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
374 Specifying attributes of variables.<br>
375 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
376 <tt>deprecated</tt>, <tt>transparent_union</tt>,
377 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000378
Chris Lattner79c3fe12003-10-02 04:57:28 +0000379 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
380 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
381 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000382 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000383
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000384 <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 +0000385 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000386 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000387
388 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
389 all target specific attributes.</li>
390
Chris Lattner79c3fe12003-10-02 04:57:28 +0000391 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
392 Other built-in functions.<br>
393 We support all builtins which have a C language equivalent (e.g.,
394 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
395 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000396 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000397
Misha Brukman500bc302003-11-22 00:38:41 +0000398 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000399
Misha Brukman500bc302003-11-22 00:38:41 +0000400 <p>The following extensions <b>are</b> known to be supported:</p>
401
Chris Lattner79c3fe12003-10-02 04:57:28 +0000402 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000403 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
404 <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>
405 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
406 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
407 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
408 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
409 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
410 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
411 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
412 <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>
413 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
414 <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 +0000415 <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 +0000416 <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 +0000417 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
418or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000419 <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 +0000420 <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 +0000421 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
422 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
423 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
424 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
425 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
426 <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>
427 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
428 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
429 <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>
430 <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>
431 <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>
432 <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>
433 <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 +0000434 </ol></li>
435
436</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000437
Misha Brukman500bc302003-11-22 00:38:41 +0000438<p>If you run into GCC extensions which have not been included in any of these
439lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000440
Misha Brukman500bc302003-11-22 00:38:41 +0000441</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000442
Misha Brukman500bc302003-11-22 00:38:41 +0000443<!-- ======================================================================= -->
444<div class="doc_subsection">
445 <a name="c++-fe">Known problems with the C++ front-end</a>
446</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000447
Misha Brukman500bc302003-11-22 00:38:41 +0000448<div class="doc_text">
449
John Criswelld000e1d2003-12-18 16:43:17 +0000450<p>For this release, the C++ front-end is considered to be fully functional but
Chris Lattner9e848092003-12-12 04:25:33 +0000451has not been tested as thoroughly as the C front-end. It has been tested and
452works for a number of non-trivial programs, but there may be lurking bugs.
453Please report any bugs or problems.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000454
455</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000456
457<!-- _______________________________________________________________________ -->
Misha Brukman500bc302003-11-22 00:38:41 +0000458<div class="doc_subsubsection">
459 Bugs
460</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000461
Misha Brukman500bc302003-11-22 00:38:41 +0000462<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000463
Misha Brukman500bc302003-11-22 00:38:41 +0000464<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000465<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000466 front-end</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000467
John Criswelld000e1d2003-12-18 16:43:17 +0000468<li>
469<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=137">
470Code is generated for empty classes.
471</a>
472</li>
473</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000474</div>
475
476<!-- _______________________________________________________________________ -->
477<div class="doc_subsubsection">
478 Notes
479</div>
480
481<div class="doc_text">
482
483<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000484
Chris Lattner79c3fe12003-10-02 04:57:28 +0000485<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
486parser is significantly more standards compliant (and picky) than prior GCC
487versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000488href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000489
490<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000491 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000492 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000493 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000494 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000495
Chris Lattner19092612003-10-02 16:38:05 +0000496<li>The LLVM C++ front-end follows the <a
497 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
498 This document, which is not Itanium specific, specifies a standard for name
499 mangling, class layout, v-table layout, RTTI formats, and other C++
500 representation issues. Because we use this API, code generated by the LLVM
501 compilers should be binary compatible with machine code generated by other
502 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
503 <i>However</i>, the exception handling mechanism used by LLVM is very
504 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000505 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000506
Misha Brukman500bc302003-11-22 00:38:41 +0000507</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000508
Misha Brukman500bc302003-11-22 00:38:41 +0000509</div>
510
511<!-- ======================================================================= -->
512<div class="doc_subsection">
513 <a name="x86-be">Known problems with the X86 back-end</a>
514</div>
515
516<div class="doc_text">
517
518<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000519
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000520<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000521href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000522support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
Misha Brukman500bc302003-11-22 00:38:41 +0000523or calls the C <tt>longjmp</tt> function will abort.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000524
Misha Brukman500bc302003-11-22 00:38:41 +0000525</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000526
Misha Brukman500bc302003-11-22 00:38:41 +0000527</div>
528
529<!-- ======================================================================= -->
530<div class="doc_subsection">
531 <a name="sparc-be">Known problems with the Sparc back-end</a>
532</div>
533
534<div class="doc_text">
535
536<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000537
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000538<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000539href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000540support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
Misha Brukman500bc302003-11-22 00:38:41 +0000541or calls the C <tt>longjmp</tt> function will abort.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000542
John Criswelld000e1d2003-12-18 16:43:17 +0000543<li>
544<a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=167">
545The llc program can crash on legal code.
546</a>
547</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000548</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000549
Misha Brukman500bc302003-11-22 00:38:41 +0000550</div>
551
552<!-- ======================================================================= -->
553<div class="doc_subsection">
554 <a name="c-be">Known problems with the C back-end</a>
555</div>
556
557<div class="doc_text">
558
559<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000560
561<li>The C back-end produces code that violates the ANSI C Type-Based Alias
562Analysis rules. As such, special options may be necessary to compile the code
563(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000564problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000565
Chris Lattnere84843b2003-10-20 19:05:03 +0000566<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000567cannot include special floating point numbers like Not-A-Number or
568Infinity.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000569
Chris Lattner2855ecd2003-11-04 20:06:53 +0000570<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000571supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000572frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000573
Misha Brukman500bc302003-11-22 00:38:41 +0000574</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000575
Misha Brukman500bc302003-11-22 00:38:41 +0000576</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000577
578<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000579<div class="doc_section">
580 <a name="additionalinfo">Additional Information</a>
581</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000582<!-- *********************************************************************** -->
583
Misha Brukman500bc302003-11-22 00:38:41 +0000584<div class="doc_text">
585
586<p>A wide variety of additional information is available on the LLVM web page,
John Criswelld000e1d2003-12-18 16:43:17 +0000587including mailing lists and publications describing algorithms and components
Chris Lattner79c3fe12003-10-02 04:57:28 +0000588implemented in LLVM. The web page also contains versions of the API
589documentation which is up-to-date with the CVS version of the source code. You
590can access versions of these documents specific to this release by going into
Misha Brukman500bc302003-11-22 00:38:41 +0000591the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000592
Misha Brukman500bc302003-11-22 00:38:41 +0000593<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner5eccca42003-12-12 21:22:16 +0000594us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
595lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000596
Misha Brukman500bc302003-11-22 00:38:41 +0000597</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000598
599<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000600
Misha Brukman500bc302003-11-22 00:38:41 +0000601<hr>
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Misha Brukmane0c891c2003-11-22 01:00:11 +0000608 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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