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Chris Lattner12d90632003-10-27 01:31:14 +0000[diff] [blame]2<html><head><title>LLVM 1.1 Release Notes</title></head>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]3<body bgcolor=white>
4
5<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
Chris Lattner12d90632003-10-27 01:31:14 +0000[diff] [blame]6<tr><td>&nbsp; <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM 1.1 Release Notes</b></font></td>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]7</tr></table>
8
9<ol>
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]10 <li><a href="#intro">Introduction</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]11 <li><a href="#whatsnew">What's New?</a>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]12 <li><a href="#portability">Portability and Supported Platforms</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]13 <li><a href="#install-instructions">Installation Instructions</a>
14 <li><a href="#knownproblems">Known Problems</a>
15 <ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]16<!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]17 <li><a href="#core">Known problems with the LLVM Core</a>
18 <li><a href="#c-fe">Known problems with the C Front-end</a>
19 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
20 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
21 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
22 <li><a href="#c-be">Known problems with the C back-end</a>
23 </ul>
24 <li><a href="#additionalinfo">Additional Information</a>
25 </ul>
26
27 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
28</ol>
29
30
31<!-- *********************************************************************** -->
32<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
33<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
34<a name="intro">Introduction
35</b></font></td></tr></table><ul>
36<!-- *********************************************************************** -->
37
38This document contains the release notes for the LLVM compiler infrastructure,
Chris Lattner12d90632003-10-27 01:31:14 +0000[diff] [blame]39release 1.1. Here we describe the status of LLVM, including any known problems,
40and bug fixes from the previous release. The most up-to-date version of this
41document can be found on the <a
42href="http://llvm.cs.uiuc.edu/releases/1.1/">LLVM 1.1 web site</a>. If you are
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]43not reading this on the LLVM web pages, you should probably go there, because
44this document may be updated after the release.<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]45
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]46For more information about LLVM, including information about potentially more
47current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
48web site</a>. If you have questions or comments, the <a
49href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
50list</a> is a good place to send them.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]51
Chris Lattner12d90632003-10-27 01:31:14 +0000[diff] [blame]52Note that if you are reading this file from CVS, that this document applies to
53the <i>next</i> release, not the previous one. To see the release notes for the
54previous release, see the <a href="http://llvm.cs.uiuc.edu/releases/">releases
55page</a>.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]56
57<!-- *********************************************************************** -->
58</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
59<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
60<a name="whatsnew">What's New?
61</b></font></td></tr></table><ul>
62<!-- *********************************************************************** -->
63
Chris Lattner12d90632003-10-27 01:31:14 +0000[diff] [blame]64This is the second public release of the LLVM compiler infrastructure. This
65release implements the following new features:<p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]66
67<ol>
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]68<li><a href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000528.html">A new LLVM profiler, similar to gprof</a> is available</li><p>
69
70<li>LLVM and the C/C++ front-end now compile on Mac OSX! Mac OSX users can now
71explore the LLVM optimizer with the C backend (note that LLVM requires GCC 3.3
72on Mac OSX).</li><p>
73
Chris Lattner2a77f2d2003-11-11 23:46:35 +0000[diff] [blame]74<li>LLVM has been <a
75href="http://mail.cs.uiuc.edu/pipermail/llvmdev/2003-November/000554.html">moved
76into an 'llvm' C++ namespace</a>, for easier integration with third-party
Misha Brukmanbfcadff2003-11-12 22:55:13 +0000[diff] [blame]77code.</a> Note that due to a bug in GDB 5.x, to debug namespacified LLVM code,
78you will need to upgrade to GDB 6.</li>
Brian Gaeke360c2662003-11-11 22:45:41 +0000[diff] [blame]79
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]80</ol><p>
81
82In this release, the following missing features were implemented:<p>
83
84<ol>
85<li><a href="http://llvm.cs.uiuc.edu/PR88">The interpreter does not support
86invoke or unwind</a></li>
Misha Brukmanc99037d2003-11-14 03:30:43 +0000[diff] [blame]87
88<li><a href="http://llvm.cs.uiuc.edu/PR99">Interpreter does not support the
89<tt>vaarg</tt> instruction</a></li><p>
90
Brian Gaekeb7508ee2003-11-16 23:49:26 +0000[diff] [blame]91<li><a href="http://llvm.cs.uiuc.edu/PR117">llvm-nm cannot read archive
92files</a></li><p>
93
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]94</ol><p>
95
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]96In this release, the following Quality of Implementation issues were fixed:<p>
97
98<ol>
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]99
100<li><a href="http://llvm.cs.uiuc.edu/PR29">C++ front-end is not generating
101linkonce linkage type when it can</a></li>
102
103<li><a href="http://llvm.cs.uiuc.edu/PR84">C front-end doesn't emit
104getelementptr for address of array element</a></li>
105
Chris Lattnerba46d552003-11-16 20:25:24 +0000[diff] [blame]106<li><a href="http://llvm.cs.uiuc.edu/PR96">Bad path to the C/C++ frontend causes
107build problems</a></li>
108
109<li><a href="http://llvm.cs.uiuc.edu/PR114">LLVM header files should be -Wold-style-cast clean</a></li>
110
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]111</ol><p>
112
Chris Lattner0ef19062003-11-08 04:28:55 +0000[diff] [blame]113
Chris Lattnerf7100202003-10-27 05:41:39 +0000[diff] [blame]114In this release, the following bugs in the previous release were fixed:<p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]115
116<ol>
Chris Lattnerf7100202003-10-27 05:41:39 +0000[diff] [blame]117<li><a href="http://llvm.cs.uiuc.edu/PR57">[inliner] Inlining invoke with PHI in unwind target is broken</a></li>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]118<li><a href="http://llvm.cs.uiuc.edu/PR58">[linker] linkonce globals should link successfully to external globals</a></li>
Chris Lattner4ad4b3a2003-10-27 17:58:57 +0000[diff] [blame]119<li><a href="http://llvm.cs.uiuc.edu/PR59">C++ frontend can crash when compiling virtual base classes</a></li>
Chris Lattner2c17a892003-10-28 23:13:03 +0000[diff] [blame]120<li><a href="http://llvm.cs.uiuc.edu/PR62">C backend fails on constant cast expr to ptr-to-anonymous struct</a></li>
Chris Lattner287b6212003-10-29 01:26:07 +0000[diff] [blame]121<li><a href="http://llvm.cs.uiuc.edu/PR63">#ident is not recognized by C frontend</a></li>
Chris Lattner32547fe2003-10-29 07:17:13 +0000[diff] [blame]122<li><a href="http://llvm.cs.uiuc.edu/PR64">[constmerge] Constant merging pass merges constants with external linkage</a></li>
123<li><a href="http://llvm.cs.uiuc.edu/PR65">C front-end miscompiles the builtin_expect intrinsic!</a></li>
Chris Lattner34790e52003-10-29 18:49:14 +0000[diff] [blame]124<li><a href="http://llvm.cs.uiuc.edu/PR66">[scalarrepl] Scalar Replacement of aggregates is decimating structures it shouldn't be</a></li>
125<li><a href="http://llvm.cs.uiuc.edu/PR67">1.0 precompiled libstdc++ does not include wchar_t support</a></li>
Chris Lattner05b958d2003-10-29 20:59:45 +0000[diff] [blame]126<li><a href="http://llvm.cs.uiuc.edu/PR68">llvmgcc asserts when compiling functions renamed with asm's</a></li>
127<li><a href="http://llvm.cs.uiuc.edu/PR69">C frontend crashes on some programs with lots of types.</a></li>
Chris Lattner36bd5d12003-10-30 01:20:42 +0000[diff] [blame]128<li><a href="http://llvm.cs.uiuc.edu/PR70">[instcombine] Resolving invoke inserts cast after terminator</a></li>
Chris Lattnerf9e8a0f2003-10-30 01:43:33 +0000[diff] [blame]129<li><a href="http://llvm.cs.uiuc.edu/PR71">llvm-as crashes when labels are used in phi nodes</a></li>
Chris Lattner3dcc7b92003-10-30 16:20:15 +0000[diff] [blame]130<li><a href="http://llvm.cs.uiuc.edu/PR72">[build problem] Callgraph.cpp not pulled in from libipa.a</a></li>
Chris Lattner3af47222003-11-16 22:11:42 +0000[diff] [blame]131<li><a href="http://llvm.cs.uiuc.edu/PR77">Variables in scope of output setjmp
132calls should be volatile</a>. Note that this does not effect correctness on
133many platforms, such as X86.
Chris Lattner8222eca2003-11-02 02:15:11 +0000[diff] [blame]134<li><a href="http://llvm.cs.uiuc.edu/PR79">llvm-gcc crashes compiling global union initializer</a></li>
135<li><a href="http://llvm.cs.uiuc.edu/PR80">C front-end crash on empty structure</a></li>
136<li><a href="http://llvm.cs.uiuc.edu/PR81">CFrontend crashes when compiling C99 compound expressions</a></li>
Chris Lattner2fb1ef82003-11-03 20:08:08 +0000[diff] [blame]137<li><a href="http://llvm.cs.uiuc.edu/PR83">[X86] Emission of global bool initializers broken</a></li>
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]138<li><a href="http://llvm.cs.uiuc.edu/PR87">llvm-gcc infinite loops on "case MAXINT:"</a></li>
Chris Lattnerde3bb572003-11-05 06:30:04 +0000[diff] [blame]139<li><a href="http://llvm.cs.uiuc.edu/PR89">[C++] Catch blocks make unparsable labels</a></li>
140<li><a href="http://llvm.cs.uiuc.edu/PR90">[C++] Initializing array with constructable objects fail</a></li>
141<li><a href="http://llvm.cs.uiuc.edu/PR91">[gccld] The -r (relinking) option does not work correctly</a></li>
Chris Lattner5b3fb032003-11-07 04:46:56 +0000[diff] [blame]142<li><a href="http://llvm.cs.uiuc.edu/PR92">[bcreader] Cannot read shift constant expressions from bytecode file</a></li>
143<li><a href="http://llvm.cs.uiuc.edu/PR93">[lowersetjmp] Lowersetjmp pass breaks dominance properties!</a></li>
144<li><a href="http://llvm.cs.uiuc.edu/PR94">llvm-gcc tries to add bools</a></li>
Chris Lattner11dde852003-11-09 19:44:07 +0000[diff] [blame]145<li><a href="http://llvm.cs.uiuc.edu/PR95">SymbolTable::getUniqueName is very inefficient</a></li>
Chris Lattner5b3fb032003-11-07 04:46:56 +0000[diff] [blame]146<li><a href="http://llvm.cs.uiuc.edu/PR98">[buildscripts] Building into objdir with .o in it fails</a></li>
Chris Lattner7af4d5e2003-11-08 05:18:50 +0000[diff] [blame]147<li><a href="http://llvm.cs.uiuc.edu/PR101">[setjmp/longjmp] Linking C programs which use setjmp/longjmp sometimes fail with references to the C++ runtime library!</a></li>
Chris Lattner11dde852003-11-09 19:44:07 +0000[diff] [blame]148<li><a href="http://llvm.cs.uiuc.edu/PR104">[c++] C++ Frontend lays out superclasses like anonymous bitfields!</a></li>
Chris Lattner9b29bde2003-11-12 04:42:37 +0000[diff] [blame]149<li><a href="http://llvm.cs.uiuc.edu/PR107">AsmParser Misses Symbol Redefinition Error</a></li>
Brian Gaeke78792062003-11-11 21:52:34 +0000[diff] [blame]150<li><a href="http://llvm.cs.uiuc.edu/PR108">gccld -Lfoo -lfoo fails to find ./foo/libfoo.a</a></li>
Chris Lattner6e4046f2003-11-14 06:42:01 +0000[diff] [blame]151<li><a href="http://llvm.cs.uiuc.edu/PR110">[bcreader] Incorrect cast causes misread forward constant references</a></li>
Brian Gaeke502c4812003-11-12 22:48:52 +0000[diff] [blame]152<li><a href="http://llvm.cs.uiuc.edu/PR112">Casting a string constant to void crashes llvm-gcc</a></li>
Chris Lattner5edc1bb2003-11-16 21:42:48 +0000[diff] [blame]153<li><a href="http://llvm.cs.uiuc.edu/PR116">[adce] ADCE considers blocks without postdominators to be unreachable</a></li>
Chris Lattner17a51ce2003-11-18 06:25:05 +0000[diff] [blame]154<li><a href="http://llvm.cs.uiuc.edu/PR54">C front-end miscompiles unsigned enums whose LLVM types are signed</a></li>
Chris Lattner43a54cc2003-11-18 23:04:02 +0000[diff] [blame^]155<li><a href="http://llvm.cs.uiuc.edu/PR123">[X86] div and rem constant exprs invalidate iterators!</a></li>
156<li><a href="http://llvm.cs.uiuc.edu/PR125">[llvmg++] Enum types are incorrectly shrunk to smaller than 'int' size</a></li>
157<li><a href="http://llvm.cs.uiuc.edu/PR128">[llvmg++] Cannot use pointer to member to initialize global</a></li>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]158</ol><p>
159
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]160At this time, LLVM is known to work properly with SPEC CPU 2000, the Olden
161benchmarks, and the Ptrdist benchmarks among many other programs. Note however
162that the Sparc and X86 backends do not currently support exception throwing or
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]163long jumping (including 253.perlbmk in SPEC). For these programs you must use
164the C backend.<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]165
166
167<!-- *********************************************************************** -->
168</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
169<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
170<a name="portability">Portability and Supported Platforms
171</b></font></td></tr></table><ul>
172<!-- *********************************************************************** -->
173
Chris Lattner3e2959e2003-11-08 05:22:09 +0000[diff] [blame]174LLVM has been extensively tested on Intel and AMD machines running Red
175Hat Linux, and Sun UltraSPARC workstations running Solaris 8. Additionally,
176LLVM works on Mac OS/X 10.3 and above, but only with the C back-end (no native
177backend for the PowerPC is available yet).
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]178The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
Chris Lattner3e2959e2003-11-08 05:22:09 +0000[diff] [blame]179work on more platforms than that. However, it is likely that we
180missed something, and that minor porting is required to get LLVM to work on
181new platforms. We welcome portability patches and error messages.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]182
183
184<!-- *********************************************************************** -->
185</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
186<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]187<a name="knownproblems">Known Problems
188</b></font></td></tr></table><ul>
189<!-- *********************************************************************** -->
190
191This section contains all known problems with the LLVM system, listed by
192component. As new problems are discovered, they will be added to these
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]193sections.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]194
195
196<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]197<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]198</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]199-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]200
201
202<!-- _______________________________________________________________________ -->
203</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
204
205<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
206
207<li>The JIT does not use mutexes to protect its internal data structures. As
208 such, execution of a threaded program could cause these data structures to
209 be corrupted.<p>
210
211<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
212
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]213<li>Linking in static archive files (.a files) is very slow (there is no symbol
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]214table in the archive).<p>
215
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]216<li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
217more than 256 elements</a>.<p>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]218
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]219<!-- _______________________________________________________________________ -->
220</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
221
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]222</ul><b>Bugs:</b><ul><p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]223
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]224<li><a href="http://llvm.cs.uiuc.edu/PR6">Oversized integer bitfields cause crash</a>.<p>
225
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]226<li>C99 Variable sized arrays do not release stack memory when they go out of
227 scope. Thus, the following program may run out of stack space:
228<pre>
229 for (i = 0; i != 1000000; ++i) {
230 int X[n];
231 foo(X);
232 }
233</pre><p>
234
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]235</ul><b>Notes:</b><ul><p>
236
237<li>Inline assembly is not yet supported.<p>
238
239<li>"long double" is transformed by the front-end into "double". There is no
240 support for floating point data types of any size other than 32 and 64 bits.
241 <p>
242
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]243<li>The following Unix system functionality has not been tested and may not work:
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]244<ol>
245 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
John Criswell97745952003-10-27 17:41:53 +0000[diff] [blame]246 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
247 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]248 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
249 - These functions have not been tested.
250</ol><p>
251
252<li>Although many GCC extensions are supported, some are not. In particular,
253 the following extensions are known to <b>not be</b> supported:
254 <ol>
255 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
256 <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.
257 <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.
258 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
259 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
260 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
261 <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.
262 <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.
263 <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.
264 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
265 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
266 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
267 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
268 </ol><p>
269
270 The following GCC extensions are <b>partially</b> supported. An ignored
271 attribute means that the LLVM compiler ignores the presence of the attribute,
272 but the code should still work. An unsupported attribute is one which is
273 ignored by the LLVM compiler, which will cause a different interpretation of
274 the program.<p>
275
276 <ol>
277 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
278 Arrays whose length is computed at run time.<br>
279 Supported, but allocated stack space is not freed until the function returns (noted above).
280
281 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
282 Declaring that functions have no side effects, or that they can never return.<br>
283 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>, <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>, <tt>deprecated</tt>,
284 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
285 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>, <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>, <tt>malloc</tt>
286 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
287 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
288 <tt>fastcall</tt>, all other target specific attributes
289
290 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
291 Specifying attributes of variables.<br>
292 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
293 <tt>deprecated</tt>, <tt>transparent_union</tt>,
294 <tt>unused</tt>, <tt>weak</tt><br>
295 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
296 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
297 <tt>vector_size</tt>, <tt>dllimport</tt>,
298 <tt>dllexport</tt>, all target specific attributes.<br>
299
300 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
301 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
302 <tt>deprecated</tt>, <tt>may_alias</tt>
303 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
304 all target specific attributes.<br>
305 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
306 Other built-in functions.<br>
307 We support all builtins which have a C language equivalent (e.g.,
308 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
309 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
310 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
311 </ol><p>
312
313
314 The following extensions <b>are</b> known to be supported:
315 <ol>
316 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
317 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]318 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]319 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
320 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
321 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
322 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
323 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
324 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
325 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
326 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
327 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
328 <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.
329 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
330 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions or arrays as values.
331 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
332
333 <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.
334 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
335 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
336
337 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
338 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
339 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
340 <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;.
341 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
342 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
343 <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.
344 <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.
345 <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.
346 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
347 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
348 </ol><p>
349
350 If you run into GCC extensions which have not been included in any of these
351 lists, please let us know (also including whether or not they work).
352
353
354<!-- _______________________________________________________________________ -->
355</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
356
John Criswell97745952003-10-27 17:41:53 +0000[diff] [blame]357For this release, the C++ front-end is considered to be fully functional but
358of <b>beta</b> quality. It has been tested and works for a number of simple programs that collectively exercise most of the language. Nevertheless, it has not been in use as long as the C front-end. Please report any bugs or problems.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]359
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]360</ul><b>Bugs</b>:<ul><p>
361
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]362<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
363 front-end</a><p>
364
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]365</ul><b>Notes</b>:<ul><p>
366
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]367<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
368parser is significantly more standards compliant (and picky) than prior GCC
369versions. For more information, see the C++ section of the <a
370href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
371
372<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]373 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]374 function and in the <tt>setjmp</tt> receiver function may not be run.
375 Objects in intervening stack frames will be destroyed however (which is
376 better than most compilers).<p>
377
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]378<li>The LLVM C++ front-end follows the <a
379 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
380 This document, which is not Itanium specific, specifies a standard for name
381 mangling, class layout, v-table layout, RTTI formats, and other C++
382 representation issues. Because we use this API, code generated by the LLVM
383 compilers should be binary compatible with machine code generated by other
384 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
385 <i>However</i>, the exception handling mechanism used by LLVM is very
386 different from the model used in the Itanium ABI, so <b>exceptions will not
387 interact correctly</b> .
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]388
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]389<li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing destructors when
390 unwinding is not shared</a> (this is a quality of implementation problem,
391 which does not effect functionality).<p>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]392
393
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]394<!-- _______________________________________________________________________ -->
395</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
396
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]397<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]398href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]399support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
400or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]401
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]402
403<!-- _______________________________________________________________________ -->
404</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
405
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]406<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]407href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]408support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
409or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]410
411
412<!-- _______________________________________________________________________ -->
413</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
414
415<li>The C back-end produces code that violates the ANSI C Type-Based Alias
416Analysis rules. As such, special options may be necessary to compile the code
417(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
418problem probably cannot be fixed.<p>
419
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]420<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
421cannot include special floating point numbers like Not-A-Number or Infinity.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]422
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]423<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]424supported</a>. This should not affect LLVM produced by the C or C++
425frontends.<p>
426
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]427<li>The code produces by the C back-end has only been tested with the Sun CC,
428GCC, and Intel compilers. It is possible that it will have to be adjusted to
429support other C compilers.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]430
431
432
433<!-- *********************************************************************** -->
434</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
435<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
436<a name="additionalinfo">Additional Information
437</b></font></td></tr></table><ul>
438<!-- *********************************************************************** -->
439
440A wide variety of additional information is available on the LLVM web page,
441including mailing lists publications describing algorithms and components
442implemented in LLVM. The web page also contains versions of the API
443documentation which is up-to-date with the CVS version of the source code. You
444can access versions of these documents specific to this release by going into
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]445the "<tt>llvm/doc/</tt>" directory in the LLVM tree.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]446
447If you have any questions or comments about LLVM, please feel free to contact us
448via the mailing lists.<p>
449
450
451<!-- *********************************************************************** -->
452</ul>
453<!-- *********************************************************************** -->
454
455<hr><font size-1>
456
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]457Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]458<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
459<!-- hhmts start -->
Chris Lattner43a54cc2003-11-18 23:04:02 +0000[diff] [blame^]460Last modified: Tue Nov 18 14:56:05 CST 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]461<!-- hhmts end -->
462</body></html>