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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / cf797e92052c16bc51df544ce02acd432475263b / . / docs / ReleaseNotes.html
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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4<head>
Reid Spencer6454ed32004-11-18 18:38:58 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]6 <link rel="stylesheet" href="llvm.css" type="text/css">
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]7 <title>LLVM 1.7 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]10
Chris Lattnerc30c5c72005-11-08 21:29:17 +0000[diff] [blame]11<div class="doc_title">LLVM 1.7 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]12
13<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]18 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]20</ol>
21
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]22<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]24</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]25
26<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]27<div class="doc_section">
28 <a name="intro">Introduction</a>
29</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]30<!-- *********************************************************************** -->
31
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]32<div class="doc_text">
33
34<p>This document contains the release notes for the LLVM compiler
Chris Lattnerc30c5c72005-11-08 21:29:17 +0000[diff] [blame]35infrastructure, release 1.7. Here we describe the status of LLVM, including any
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]36known problems and major improvements from the previous release. The most
37up-to-date version of this document can be found on the <a
Chris Lattnerc30c5c72005-11-08 21:29:17 +0000[diff] [blame]38href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]39not reading this on the LLVM web pages, you should probably go there because
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]40this document may be updated after the release.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]41
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]42<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]43release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]44web site</a>. If you have questions or comments, the <a
45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]46list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]47
Chris Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]48<p>Note that if you are reading this file from CVS or the main LLVM web page,
49this document applies to the <i>next</i> release, not the current one. To see
50the release notes for the current or previous releases, see the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]51href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]52
53</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]54
55<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]56<div class="doc_section">
57 <a name="whatsnew">What's New?</a>
58</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]59<!-- *********************************************************************** -->
60
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]61<div class="doc_text">
62
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]63<p>This is the eighth public release of the LLVM Compiler Infrastructure. This
64release incorporates a large number of enhancements and new features,
65including vector support (Intel SSE and Altivec), a new GCC4.0-based
66C/C++ front-end, Objective C/C++ support, inline assembly support, and many
67other big features.
68</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]69
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]70</div>
71
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]72<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]73<div class="doc_subsection">
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]74<a name="newfeatures">New Features in LLVM 1.7</a>
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]75</div>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]76
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]77<!--_________________________________________________________________________-->
78<div class="doc_subsubsection"><a name="llvmgcc4">GCC4.0-based llvm-gcc
79front-end</a></div>
80
81<div class="doc_text">
82
83<p>LLVM 1.8 includes a brand new llvm-gcc, based on GCC 4.0.1. This version
84of llvm-gcc solves many serious long-standing problems with llvm-gcc, including
85all of those blocked by the <a href="http://llvm.org/PR498">llvm-gcc 4 meta
86bug</a>. In addition, llvm-gcc4 implements support for many new features,
87including GCC inline assembly, generic vector support, SSE and Altivec
88intrinsics, and several new GCC attributes. In addition, llvm-gcc4 is
89significantly faster than llvm-gcc3, respects -O options, its -c/-S options
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]90correspond to GCC's (they emit native code), and it has debugging support well
91underway.</p>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]92
93<p>If you can use it, llvm-gcc4 is offers significant new functionality, and we
94hope that it will replace llvm-gcc3 completely in a future release.
95Unfortunately, it does not currently support C++ exception handling at all, and
96it only works on Apple Mac OS/X machines with X86 or PowerPC processors.
97</p>
98
99</div>
100
101<!--_________________________________________________________________________-->
102<div class="doc_subsubsection"><a name="inlineasm">Inline Assembly
103Support</a></div>
104
105<div class="doc_text">
106
107<p>The LLVM IR and llvm-gcc4 front-end now fully support arbitrary GCC <a
108href="LangRef.html#inlineasm">inline assembly</a>. The LLVM X86 and PowerPC
109code generators have initial support for it,
110being able to compile basic statements, but are missing some features. Please
111report any inline asm statements that crash the compiler or that are miscompiled
112as bugs.</p>
113
114</div>
115
116<!--_________________________________________________________________________-->
117<div class="doc_subsubsection"><a name="newsparc">New SPARC backend</a></div>
118
119<div class="doc_text">
120
121<p>LLVM 1.7 includes a new, fully functional, SPARC backend built in the
122target-independent code generator. This SPARC backend includes support for
123SPARC V8 and SPARC V9 subtargets (controlling whether V9 features can be used),
124and targets the 32-bit SPARC ABI.</p>
125
126<p>The LLVM 1.7 release is the last release that will include the LLVM "SparcV9"
127backend, which was the very first LLVM native code generator. In 1.8, it will
128be removed, replaced with the new SPARC backend.</p>
129
130</div>
131
132<!--_________________________________________________________________________-->
133<div class="doc_subsubsection"><a name="genvector">Generic Vector Support
134</a></div>
135
136<div class="doc_text">
137
138<p>LLVM now includes significantly extended support for SIMD vectors in its
139core instruction set. It now includes three new instructions for manipulating
140vectors: <a href="LangRef.html#i_extractelement"><tt>extractelement</tt></a>,
141<a href="LangRef.html#i_insertelement"><tt>insertelement</tt></a>, and
142<a href="LangRef.html#i_shufflevector"><tt>shufflevector</tt></a>. Further,
143many bugs in vector handling have been fixed, and vectors are now supported by
144the target-independent code generator. For example, if a vector operation is
145not supported by a particular target, it will be correctly broken down and
146executed as scalar operations.</p>
147
148<p>Because llvm-gcc3 does not support GCC generic vectors or vector intrinsics,
149so llvm-gcc4 must be used.</p>
150</div>
151
152
153<!--_________________________________________________________________________-->
154<div class="doc_subsubsection"><a name="ssealtivec">Intel SSE and PowerPC
155Altivec support
156</a></div>
157
158<div class="doc_text">
159
160<p>The LLVM X86 backend now supports Intel SSE 1, 2, and 3, and now uses scalar
161SSE operations to implement scalar floating point math when the target supports
162SSE1 (for floats) or SSE2 (for doubles). Vector SSE instructions are generated
163by llvm-gcc4 when the generic vector mechanism or specific SSE intrinsics are
164used.
165</p>
166
167<p>The LLVM PowerPC backend now supports the Altivec instruction set, including
168both GCC -maltivec and -faltivec modes. Altivec instructions are generated
169by llvm-gcc4 when the generic vector mechanism or specific Altivec intrinsics
170are used.
171</p>
172
173</div>
174
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]175<!--_________________________________________________________________________-->
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]176<div class="doc_subsubsection"><a name="optimizernew">Optimizer
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]177Improvements</a></div>
178
179<div class="doc_text">
180<ul>
181<li>The Loop Unswitching pass (<tt>-loop-unswitch</tt>) has had several bugs
182 fixed, has several new features, and is enabled by default in llvmgcc3
183 now.</li>
184<li>The Loop Strength Reduction pass (<tt>-loop-reduce</tt>) is now enabled for
185 the X86 backend.</li>
186<li>The Instruction Combining pass (<tt>-instcombine</tt>) now includes a
187 framework and implementation for simplifying code based on whether computed
188 bits are demanded or not.</li>
189<li>The Scalar Replacement of Aggregates pass (<tt>-scalarrepl</tt>) can now
190 promote simple unions to registers.</li>
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]191<li>The Reassociation pass (<tt>-reassociate</tt>) can now
192 factor expressions, e.g. turning "A*A+A*B" into "A*(A+B)".</li>
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]193<li>Several LLVM passes are <a href="http://llvm.org/PR681">significantly
194faster</a>.</li>
195</ul>
196</div>
197
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]198<!--_________________________________________________________________________-->
199<div class="doc_subsubsection"><a name="codgennew">Code Generator
200Improvements</a></div>
201
202<div class="doc_text">
203<ul>
204<li>LLVM has a new prepass (before register allocation) list scheduler, which
205 supports bottom-up and top-down scheduling, pluggable priority functions and
206 pluggable hazard recognizers. The X86 backend uses this to reduce register
207 pressure and RISC targets schedule based on operation latency.</li>
208<li>The tblgen-based target description framework introduced in LLVM 1.6 has
209 several new features, useful for targets that can fold loads and stores into
210 operations, and features that make the .td files more expressive.</li>
211<li>The instruction selector is significantly faster in 1.7 than in 1.6.</li>
212<li>The X86, Alpha and Itanium backends use new DAG-DAG instruction selectors,
213 making them easier to maintain and generate slightly better code.</li>
214<li>The X86 backend now supports generation of Scalar SSE code for scalar FP
215 expressions. LLVM provides significantly better performance with Scalar SSE
216 instructions than it does with the Intel floating point stack
217 instructions.</li>
218<li>The Itanium backend now has a bundling pass, which improves performance
219 by ~10% and reduces code size (previously it unconditionally inserted a stop
220 bit after every instruction).</li>
221</ul>
222</div>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]223
224<!--_________________________________________________________________________-->
225<div class="doc_subsubsection"><a name="othernew">Other New Features</a></div>
226
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]227<div class="doc_text">
228<ul>
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]229<li>The Mac OS/X PowerPC and X86 backends now have initial support Darwin DWARF
230 debugging information, however, debug info generation has been disabled for
231 the 1.7 release in llvmgcc4.</li>
232<li>LLVM includes the new <a href="docs/CommandGuide/html/llvm-config.html">
233 llvm-config</a> utility, which makes it easier to build and link programs
234 against the LLVM libraries when not using the LLVM makefiles.</li>
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]235<li>LLVM now supports first class global ctor/dtor initialization lists, no
236 longer forcing targets to use "__main".</li>
237<li>LLVM supports assigning globals and functions to a particular section
238 in the result executable using the GCC section attribute.</li>
239<li><a href="ExtendingLLVM.html">Adding intrinsics to LLVM</a> is now
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]240 significantly easier.</li>
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]241<li>llvmgcc4 now fully supports C99 Variable Length Arrays, including dynamic
242 stack deallocation.</li>
243
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]244</ul>
245</div>
John Criswelle531ec52005-06-29 16:22:34 +0000[diff] [blame]246
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]247
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]248<!--=========================================================================-->
249<div class="doc_subsection">
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]250<a name="changes">Significant Changes in LLVM 1.7</a>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]251</div>
252
253<div class="doc_text">
254<ul>
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]255<li>The official LLVM URL is now <a href="http://llvm.org/">
256 http://llvm.org/</a>.</li>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]257<li>The LLVM intrinsics used to be overloaded based on type: for example,
258 <a href="LangRef.html#int_ctpop"><tt>llvm.ctpop</tt></a> could work with any
259 integer datatype. They are now separated into different intrinsics with
260 suffixes to denote their argument type (e.g. <tt>llvm.ctpop.i32</tt>)). Old
261 LLVM .ll and .bc files that use these intrinsics will continue to work with
262 new LLVM versions (they are transparently upgraded by the parsers), but will
263 cause a warning to be emitted.</li>
264<li>The <tt>llvm.readport</tt>, <tt>llvm.writeport</tt>, <tt>llvm.readio</tt>,
265 and <tt>llvm.writeio</tt> intrinsics have been removed. The first two
266 were ever only supported by the X86 backend, the last two were never
267 correctly supported by any target, and none were accessible through the
268 C front-end. Inline assembly support can now be used to
269 implement these operations.</li>
270<li>The <tt>llvm-db</tt> tool had basic support for stepping through code, which
271 used the JIT. This code has been removed, and DWARF emission support added
272 instead. <tt>llvm-db</tt> still exists in CVS if someone wanted to write a
273 <tt>ptrace</tt> backend for it.</li>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]274</ul>
275</div>
276
277
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]278<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]279<div class="doc_section">
280 <a name="portability">Portability and Supported Platforms</a>
281</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]282<!-- *********************************************************************** -->
283
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]284<div class="doc_text">
285
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]286<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]287
288<ul>
Reid Spencer00812e22005-05-17 02:47:27 +0000[diff] [blame]289 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
290 (and probably other unix-like systems).</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]291<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]292<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
293 support is available for native builds with Visual C++).</li>
Chris Lattnerfeaf9602005-10-29 05:14:01 +0000[diff] [blame]294<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]295<li>Alpha-based machines running Debian GNU/Linux.</li>
296<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]297</ul>
298
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]299<p>The core LLVM infrastructure uses
300<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
301to the machine and operating system on which it is built. However, minor
302porting may be required to get LLVM to work on new platforms. We welcome your
303portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]304
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]305</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]306
307<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]308<div class="doc_section">
309 <a name="knownproblems">Known Problems</a>
310</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]311<!-- *********************************************************************** -->
312
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]313<div class="doc_text">
314
315<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]316component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]317sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]318href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]319there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]320
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]321</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]322
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]323<!-- ======================================================================= -->
324<div class="doc_subsection">
325 <a name="experimental">Experimental features included with this release</a>
326</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]327
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]328<div class="doc_text">
329
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]330<p>The following components of this LLVM release are either untested, known to
331be broken or unreliable, or are in early development. These components should
332not be relied on, and bugs should not be filed against them, but they may be
333useful to some people. In particular, if you would like to work on one of these
334components, please contact us on the llvmdev list.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]335
336<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]337<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
338 future release.</li>
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]339<li>The IA64 code generator is experimental.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]340<li>The Alpha JIT is experimental.</li>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]341<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
342 <tt>-filetype</tt> llc option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]343</ul>
344
345</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]346
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]347<!-- ======================================================================= -->
348<div class="doc_subsection">
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]349 <a name="build">Known problems with the Build System</a>
350</div>
351
352<div class="doc_text">
353
354<ul>
355 <li>The <a href="http://llvm.org/PR656">configure script sometimes fails on Solaris/Sparc</a>. A work around is documented in <a href="http://llvm.org/PR656">PR656.</a></li>
356</ul>
357</div>
358
359
360<!-- ======================================================================= -->
361<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]362 <a name="core">Known problems with the LLVM Core</a>
363</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]364
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]365<div class="doc_text">
366
367<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]368 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
369 work.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]370</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]371</div>
372
373<!-- ======================================================================= -->
374<div class="doc_subsection">
375 <a name="c-fe">Known problems with the C front-end</a>
376</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]377
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]378<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]379<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]380
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]381<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]382
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]383<p>
384llvm-gcc3 has many significant problems that are fixed by llvm-gcc4. See
385 those blocked on the <a href="http://llvm.org/PR498">llvm-gcc4 meta bug</a>.
Chris Lattnercf797e92006-04-19 04:12:01 +0000[diff] [blame^]386Two major ones include:</p>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]387
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]388<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]389<li>With llvm-gcc3,
390 C99 variable sized arrays do not release stack memory when they go out of
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]391 scope. Thus, the following program may run out of stack space:
392<pre>
393 for (i = 0; i != 1000000; ++i) {
394 int X[n];
395 foo(X);
396 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]397</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]398
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]399<li>With llvm-gcc3, Initialization of global union variables can only be done <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]400href="http://llvm.org/PR162">with the largest union member</a>.</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]401
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]402</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]403</div>
404
405<!-- _______________________________________________________________________ -->
406<div class="doc_subsubsection">
407 Notes
408</div>
409
410<div class="doc_text">
411
412<ul>
413
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]414<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]415support for floating point data types of any size other than 32 and 64
416bits.</li>
417
418<li>The following Unix system functionality has not been tested and may not
419work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]420 <ol>
421 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
422 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
423 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
424 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
425 - These functions have not been tested.
426 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]427
428<li>Although many GCC extensions are supported, some are not. In particular,
429 the following extensions are known to <b>not be</b> supported:
430 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]431 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]432 <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>
433 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
434 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]435 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]436 <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>
437 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]438 <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>
439 <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>
Tanya Lattner014e5f52004-12-08 18:25:34 +0000[diff] [blame]440 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]441 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]442 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]443
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]444 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]445 attribute means that the LLVM compiler ignores the presence of the attribute,
446 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]447 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]448 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]449
450 <ol>
451 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
452 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]453 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]454
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]456
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]457 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]458 return.<br>
459
460 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]461 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Chris Lattneraef8c642005-12-05 05:23:06 +0000[diff] [blame]462 <tt>unused</tt>, <tt>used</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]463 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
464
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]465 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]466 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
467 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
468
Chris Lattneraef8c642005-12-05 05:23:06 +0000[diff] [blame]469 <b>Unsupported:</b> <tt>section</tt>, <tt>alias</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]470 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
471 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]472
473 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
474 Specifying attributes of variables.<br>
475 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
476 <tt>deprecated</tt>, <tt>transparent_union</tt>,
Chris Lattneraef8c642005-12-05 05:23:06 +0000[diff] [blame]477 <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]478
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]479 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
480 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
481 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]482 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]483
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]484 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]485 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]486 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]487
488 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
489 all target specific attributes.</li>
490
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]491 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
492 Other built-in functions.<br>
493 We support all builtins which have a C language equivalent (e.g.,
494 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
495 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000[diff] [blame]496 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
497 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]498 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
499 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
500 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]501 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]502
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]503 <p>The following extensions <b>are</b> known to be supported:</p>
504
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]505 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]506 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]507 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
508 <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>
Tanya Lattnerca26c3e2004-06-22 03:48:17 +0000[diff] [blame]509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]510 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
511 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
512 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
514 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
515 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
516 <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>
517 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
518 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]519 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]520 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]521 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
522or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]523 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]524 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]525 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
526 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
527 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
Tanya Lattner78537e42004-12-08 18:29:38 +0000[diff] [blame]528 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]529 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
530 <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>
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
532 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
533 <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>
534 <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>
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
Chris Lattner25795bc2004-02-14 04:08:29 +0000[diff] [blame]536 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]537 <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>
538 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]539 </ol></li>
540
541</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]542
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]543<p>If you run into GCC extensions which have not been included in any of these
544lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]545
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]546</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]547
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]548<!-- ======================================================================= -->
549<div class="doc_subsection">
550 <a name="c++-fe">Known problems with the C++ front-end</a>
551</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]552
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]553<div class="doc_text">
554
Reid Spencere09ca642004-12-07 08:39:08 +0000[diff] [blame]555<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]556tested and works for a number of non-trivial programs, including LLVM
557itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]558
559</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]560
561<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]562<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]563
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]564<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]565
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]566<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]567<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]568 front-end</a>.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]569
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]570</ul>
571
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]572</div>
573
574<!-- _______________________________________________________________________ -->
575<div class="doc_subsubsection">
576 Notes
577</div>
578
579<div class="doc_text">
580
581<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]582
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]583<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]584 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]585 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]586 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]587 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]588
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]589<li>The LLVM C++ front-end follows the <a
590 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
591 This document, which is not Itanium specific, specifies a standard for name
592 mangling, class layout, v-table layout, RTTI formats, and other C++
593 representation issues. Because we use this API, code generated by the LLVM
594 compilers should be binary compatible with machine code generated by other
595 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
596 <i>However</i>, the exception handling mechanism used by LLVM is very
597 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]598 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]599
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]600</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]601
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]602</div>
603
604<!-- ======================================================================= -->
605<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]606 <a name="c-be">Known problems with the C back-end</a>
607</div>
608
609<div class="doc_text">
610
611<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]612
613<li>The C back-end produces code that violates the ANSI C Type-Based Alias
614Analysis rules. As such, special options may be necessary to compile the code
615(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]616problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]617
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]618<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]619supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]620frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]621
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]622<li>The C backend does not correctly implement the <a
623href="LangRef.html#i_stacksave"><tt>llvm.stacksave</tt></a> or
624<a href="LangRef.html#i_stackrestore"><tt>llvm.stackrestore</tt></a>
625intrinsics. This means that some code compiled by it can run out of stack
626space if they depend on these (e.g. C99 varargs).</li>
627
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]628</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]629
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]630</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]631
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]632<!-- ======================================================================= -->
633<div class="doc_subsection">
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]634 <a name="x86-be">Known problems with the X86 back-end</a>
635</div>
636
637<div class="doc_text">
638
639<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]640<li><a href="http://llvm.org/PR736">Indirect calls crash JIT on
641Darwin/x86</a>.</li>
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]642</ul>
643
644</div>
645
646<!-- ======================================================================= -->
647<div class="doc_subsection">
648 <a name="ppc-be">Known problems with the PowerPC back-end</a>
649</div>
650
651<div class="doc_text">
652
653<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]654<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
655implement ordered FP comparisons</a>.</li>
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]656</ul>
657
658</div>
659
660<!-- ======================================================================= -->
661<div class="doc_subsection">
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]662 <a name="alpha-be">Known problems with the Alpha back-end</a>
663</div>
664
665<div class="doc_text">
666
667<ul>
668
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]669<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
670appropriate nops inserted to ensure restartability.</li>
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]671
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]672</ul>
673
674</div>
675
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]676<!-- ======================================================================= -->
677<div class="doc_subsection">
678 <a name="ia64-be">Known problems with the IA64 back-end</a>
679</div>
680
681<div class="doc_text">
682
683<ul>
684
685<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
686made where the argument is not 16-byte aligned, as required on IA64. (Strictly
687speaking this is not a bug in the IA64 back-end; it will also be encountered
688when building C++ programs using the C back-end.)</li>
689
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]690<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]691ABI compliant layout of v-tables</a>. In particular, it just stores function
692pointers instead of function descriptors in the vtable. This bug prevents
693mixing C++ code compiled with LLVM with C++ objects compiled by other C++
694compilers.</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]695
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]696<li>There are a few ABI violations which will lead to problems when mixing LLVM
697output with code built with other compilers, particularly for floating-point
698programs.</li>
699
700<li>Defining vararg functions is not supported (but calling them is ok).</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]701
702</ul>
703
704</div>
705
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]706<!-- ======================================================================= -->
707<div class="doc_subsection">
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]708 <a name="sparc-be">Known problems with the SPARC back-end</a>
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]709</div>
710
711<div class="doc_text">
712
713<ul>
Chris Lattnerc71173a2006-04-19 04:05:21 +0000[diff] [blame]714<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
715 support the 64-bit SPARC ABI (-m64).</li>
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]716</ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]717
718</div>
719
720
721<!-- ======================================================================= -->
722<div class="doc_subsection">
723 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
724</div>
725
726<div class="doc_text">
727
728<ul>
729<li><a href="http://llvm.org/PR60">[sparcv9] SparcV9 backend miscompiles
730several programs in the LLVM test suite</a></li>
731<li>The SparcV9 backend is slated to be removed before the LLVM 1.8
732 release.</li>
733</ul>
734
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]735</div>
736
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]737<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]738<div class="doc_section">
739 <a name="additionalinfo">Additional Information</a>
740</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]741<!-- *********************************************************************** -->
742
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]743<div class="doc_text">
744
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]745<p>A wide variety of additional information is available on the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]746href="http://llvm.org">LLVM web page</a>, including <a
747href="http://llvm.org/docs/">documentation</a> and <a
748href="http://llvm.org/pubs/">publications describing algorithms and
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]749components implemented in LLVM</a>. The web page also contains versions of the
750API documentation which is up-to-date with the CVS version of the source code.
751You can access versions of these documents specific to this release by going
752into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]753
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]754<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]755us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]756lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]757
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]758</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]759
760<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]761
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]762<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]763<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]764 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]765 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
766 <a href="http://validator.w3.org/check/referer"><img
767 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
768
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]769 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]770 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]771</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]772
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]773</body>
774</html>