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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / c0c186d140b75fc3b2e4e3632f826a40cf4f8626 / . / 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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3<html>
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">
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]7 <title>LLVM 1.6 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
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]11<div class="doc_title">LLVM 1.6 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
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]35infrastructure, release 1.6. 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 Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]38href="http://llvm.org/releases/1.6/">LLVM 1.6 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 Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]63<p>This is the seventh public release of the LLVM Compiler Infrastructure. This
64release incorporates a large number of enhancements and additions (primarily in
65the code generator), which combine to improve the quality of the code generated
66by LLVM by up to 30% in some cases. This release is also the first release to
Chris Lattnerf2548362005-11-03 22:33:48 +0000[diff] [blame]67have first-class support for Mac OS X: all of the major bugs have been shaken
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]68out and it is now as well supported as Linux on X86.</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">
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]74<a name="newfeatures">New Features in LLVM 1.6</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 Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]77<!--_________________________________________________________________________-->
78<div class="doc_subsubsection"><a name="iselgen">Instruction Selector
79Generation from Target Description</a></div>
80
81<div class="doc_text">
82<p>LLVM now includes support for auto-generating large portions of the
83instruction selectors from target descriptions. This allows us to
84write patterns in the target .td file, instead of writing lots of
85nasty C++ code. Most of the PowerPC instruction selector is now
86generated from the PowerPC target description files and other targets
87are adding support that will be live for LLVM 1.7.</p>
88
89<p>For example, here are some patterns used by the PowerPC backend. A
90floating-point multiply then subtract instruction (FMSUBS):</p>
91
92<div class="doc_code"><p>
93<tt>(set F4RC:$FRT, (fsub (fmul F4RC:$FRA, F4RC:$FRC), F4RC:$FRB))</tt>
94</p></div>
95
96<p>Exclusive-or by 16-bit immediate (XORI):</p>
97
98<div class="doc_code"><p>
99<tt>(set GPRC:$dst, (xor GPRC:$src1, immZExt16:$src2))</tt>
100</p></div>
101
102<p>Exclusive-or by 16-bit immediate shifted right 16-bits (XORIS):</p>
103
104<div class="doc_code"><p>
105<tt>(set GPRC:$dst, (xor GPRC:$src1, imm16Shifted:$src2))</tt>
106</p></div>
107
108<p>With these definitions, we teach the code generator how to combine these two
109instructions to xor an abitrary 32-bit immediate with the following
110definition. The first line specifies what to match (a xor with an arbitrary
111immediate) the second line specifies what to produce:</p>
112
113<div class="doc_code"><p>
Chris Lattner6e520d02005-10-29 07:08:19 +0000[diff] [blame]114<pre>def : Pat&lt;(xor GPRC:$in, imm:$imm),
115 (XORIS (XORI GPRC:$in, (LO16 imm:$imm)), (HI16 imm:$imm))&gt;;
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]116</pre>
117</p></div>
118
119</div>
120
121<!--_________________________________________________________________________-->
122<div class="doc_subsubsection"><a name="sched">Instruction Scheduling
123Support</a></div>
124
125<div class="doc_text">
126
127<p>Instruction selectors using the refined <a
128href="CodeGenerator.html#instselect">instruction selection framework</a> can now
129use a simple pre-pass scheduler included with LLVM 1.6. This scheduler is
130currently simple (cannot be configured much by the targets), but will be
131extended in the future.</p>
132</div>
133
134<!--_________________________________________________________________________-->
135<div class="doc_subsubsection"><a name="subtarget">Code Generator Subtarget
136Support</a></div>
137
138<div class="doc_text">
139<p>It is now straight-forward to parameterize a target implementation, and
140provide a mapping from CPU names to sets of target parameters. LLC now supports
141a <tt>-mcpu=cpu</tt> option that lets you choose a subtarget by CPU name: use
142"<tt>llvm-as &lt; /dev/null | llc -march=XXX -mcpu=help</tt>" to get a list of
143supported CPUs for target "XXX". It also provides a
144<tt>-mattr=+attr1,-attr2</tt> option that can be used to control individual
145features of a target (the previous command will list available features as
146well).</p>
147
148<p>This functionality is nice when you want tell LLC something like "compile to
149code that is specialized for the PowerPC G5, but doesn't use altivec code. In
150this case, using "<tt>llc -march=ppc32 -mcpu=g5 -mattr=-altivec</tt>".</p>
151
152</div>
153
154<!--_________________________________________________________________________-->
155<div class="doc_subsubsection"><a name="jitlock">Other New Features</a></div>
156
Chris Lattnerebc8c7d2005-05-18 22:23:56 +0000[diff] [blame]157<div class="doc_text">
Reid Spencerfce2ddc2005-07-12 16:36:24 +0000[diff] [blame]158<ol>
159 <li>The JIT now uses mutexes to protect its internal data structures. This
160 allows multi-threaded programs to be run from the JIT or interpreter without
161 corruption of the internal data structures. See
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]162 <a href="http://llvm.org/PR418">PR418</a> and
163 <a href="http://llvm.org/PR540">PR540</a> for the details.
Reid Spencerfce2ddc2005-07-12 16:36:24 +0000[diff] [blame]164 </li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]165 <li>LLVM on Win32 <a href="http://llvm.org/PR614">no longer requires sed,
166 flex, or bison when compiling with Visual C++</a>.</li>
167 <li>The llvm-test suite can now use the NAG Fortran to C compiler to compile
168 SPEC FP programs if available (allowing us to test all of SPEC'95 &amp;
169 2000).</li>
170 <li>When bugpoint is grinding away and the user hits ctrl-C, it now
171 gracefully stops and gives what it has reduced so far, instead of
172 giving up completely. In addition, <a href="http://llvm.org/PR576">the JIT
173 debugging mode of bugpoint is much faster</a>.</li>
174 <li>LLVM now includes Xcode project files in the llvm/Xcode directory.</li>
Chris Lattnerf2548362005-11-03 22:33:48 +0000[diff] [blame]175 <li>LLVM now supports Mac OS X on Intel.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]176 <li>LLVM now builds cleanly with GCC 4.1.</li>
Reid Spencerfce2ddc2005-07-12 16:36:24 +0000[diff] [blame]177</ol>
Chris Lattnerebc8c7d2005-05-18 22:23:56 +0000[diff] [blame]178</div>
179
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]180<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]181<div class="doc_subsection">
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]182<a name="codequality">Code Quality Improvements in LLVM 1.6</a>
Chris Lattneraab56d42004-05-23 20:42:08 +0000[diff] [blame]183</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]184
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]185<div class="doc_text">
186<ol>
187 <li>The <tt>-globalopt</tt> pass can now statically evaluate C++ static
188 constructors when they are simple enough. For example, it can
189 now statically initialize "<tt>struct X { int a; X() : a(4) {} } g;</tt>".
190 </li>
191 <li>The Loop Strength Reduction pass has been completely rewritten, is far
192 more aggressive, and is turned on by default in the RISC targets. On PPC,
193 we find that it often speeds up programs from 10-40% depending on the
194 program.</li>
195 <li>The code produced when exception handling is enabled is far more
Chris Lattnerf2548362005-11-03 22:33:48 +0000[diff] [blame]196 efficient in some cases, particularly on Mac OS X.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]197</ol>
198</div>
199
200
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]201<!--=========================================================================-->
202<div class="doc_subsection">
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]203<a name="codequality">Code Generator Improvements in LLVM 1.6</a>
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]204</div>
205
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]206<div class="doc_text">
207<ol>
208<li>The Alpha backend is substantially more stable and robust than in LLVM 1.5.
209 For example, it now fully supports varargs functions. The Alpha backend
210 also now features beta JIT support.</li>
211<li>The code generator contains a new component, the DAG Combiner. This allows
212 us to optimize lowered code (e.g. after 64-bit operations have been lowered
213 to use 32-bit registers on 32-bit targets) and do fine-grained bit-twiddling
214 optimizations for the backend.</li>
215<li>The SelectionDAG infrastructure is far more capable and mature, able to
216 handle many new target peculiarities in a target-independent way.</li>
217<li>The default <a href="http://llvm.org/PR547">register allocator is now far
218 faster on some testcases</a>,
219 particularly on targets with a large number of registers (e.g. IA64
220 and PPC).</li>
221</ol>
222</div>
223
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]224<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]225<div class="doc_subsection">
John Criswell98391ce2005-05-18 20:28:46 +0000[diff] [blame]226<a name="bugfix">Significant Bugs Fixed in LLVM 1.6</a>
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]227</div>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]228
John Criswelle531ec52005-06-29 16:22:34 +0000[diff] [blame]229<div class="doc_text">
230<ol>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]231 <li>A vast number of bugs have been fixed in the PowerPC backend and in
Chris Lattnerf2548362005-11-03 22:33:48 +0000[diff] [blame]232 llvm-gcc when configured for Mac OS X (particularly relating to ABI
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]233 issues). For example:
234 <a href="http://llvm.org/PR603">PR449</a>,
235 <a href="http://llvm.org/PR594">PR594</a>,
236 <a href="http://llvm.org/PR603">PR603</a>,
237 <a href="http://llvm.org/PR609">PR609</a>,
238 <a href="http://llvm.org/PR630">PR630</a>,
239 <a href="http://llvm.org/PR643">PR643</a>,
240 and several others without bugzilla bugs.</li>
241 <li>Several bugs in tail call support have been fixed.</li>
242 <li><a href="http://llvm.org/PR608">configure does not correctly detect gcc
243 version on cygwin</a>.</li>
244 <li>Many many other random bugs have been fixed. Query <a
245 href="http://llvm.org/bugs">our bugzilla</a> with a target of 1.6 for more
246 information.</li>
John Criswelle531ec52005-06-29 16:22:34 +0000[diff] [blame]247</ol>
248</div>
249
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]250<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]251<div class="doc_section">
252 <a name="portability">Portability and Supported Platforms</a>
253</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]254<!-- *********************************************************************** -->
255
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]256<div class="doc_text">
257
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]258<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]259
260<ul>
Reid Spencer00812e22005-05-17 02:47:27 +0000[diff] [blame]261 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
262 (and probably other unix-like systems).</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]263<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]264<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
265 support is available for native builds with Visual C++).</li>
Chris Lattnerfeaf9602005-10-29 05:14:01 +0000[diff] [blame]266<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]267<li>Alpha-based machines running Debian GNU/Linux.</li>
268<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]269</ul>
270
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]271<p>The core LLVM infrastructure uses
272<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
273to the machine and operating system on which it is built. However, minor
274porting may be required to get LLVM to work on new platforms. We welcome your
275portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]276
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]277</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]278
279<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]280<div class="doc_section">
281 <a name="knownproblems">Known Problems</a>
282</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]283<!-- *********************************************************************** -->
284
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]285<div class="doc_text">
286
287<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]288component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]289sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]290href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]291there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]292
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]293</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]294
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]295<!-- ======================================================================= -->
296<div class="doc_subsection">
297 <a name="experimental">Experimental features included with this release</a>
298</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]299
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]300<div class="doc_text">
301
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]302<p>The following components of this LLVM release are either untested, known to
303be broken or unreliable, or are in early development. These components should
304not be relied on, and bugs should not be filed against them, but they may be
305useful to some people. In particular, if you would like to work on one of these
306components, please contact us on the llvmdev list.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]307
308<ul>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]309<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattnere9412172005-10-24 02:33:44 +0000[diff] [blame]310 releases: <tt>-cee, -pre</tt></li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]311<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
312 be used to step through programs and inspect the stack.</li>
Chris Lattnereaf0f2b2005-10-24 16:36:36 +0000[diff] [blame]313<li>The SparcV8 and IA64 code generators are experimental.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]314<li>The Alpha JIT is experimental.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]315</ul>
316
317</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]318
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]319<!-- ======================================================================= -->
320<div class="doc_subsection">
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame^]321 <a name="build">Known problems with the Build System</a>
322</div>
323
324<div class="doc_text">
325
326<ul>
327 <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>
328</ul>
329</div>
330
331
332<!-- ======================================================================= -->
333<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]334 <a name="core">Known problems with the LLVM Core</a>
335</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]336
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]337<div class="doc_text">
338
339<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]340 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
341 work.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]342</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]343</div>
344
345<!-- ======================================================================= -->
346<div class="doc_subsection">
347 <a name="c-fe">Known problems with the C front-end</a>
348</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]349
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]350<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]351<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]352
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]353<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]354<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]355<li>C99 Variable sized arrays do not release stack memory when they go out of
356 scope. Thus, the following program may run out of stack space:
357<pre>
358 for (i = 0; i != 1000000; ++i) {
359 int X[n];
360 foo(X);
361 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]362</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]363
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]364<li>Initialization of global union variables can only be done <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]365href="http://llvm.org/PR162">with the largest union member</a>.</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]366
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]367</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]368</div>
369
370<!-- _______________________________________________________________________ -->
371<div class="doc_subsubsection">
372 Notes
373</div>
374
375<div class="doc_text">
376
377<ul>
378
379<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]380
381<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]382support for floating point data types of any size other than 32 and 64
383bits.</li>
384
385<li>The following Unix system functionality has not been tested and may not
386work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]387 <ol>
388 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
389 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
390 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
391 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
392 - These functions have not been tested.
393 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]394
395<li>Although many GCC extensions are supported, some are not. In particular,
396 the following extensions are known to <b>not be</b> supported:
397 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]398 <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]399 <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>
400 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
401 <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]402 <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]403 <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>
404 <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]405 <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>
406 <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]407 <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]408 <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]409 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]410
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]411 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]412 attribute means that the LLVM compiler ignores the presence of the attribute,
413 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]414 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]415 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]416
417 <ol>
418 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
419 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]420 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]421
422 <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]423
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]424 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]425 return.<br>
426
427 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]428 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
429 <tt>unused</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]430 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
431
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]432 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]433 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
434 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
435
436 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
437 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
438 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]439
440 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
441 Specifying attributes of variables.<br>
442 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
443 <tt>deprecated</tt>, <tt>transparent_union</tt>,
444 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]445
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]446 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
447 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
448 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]449 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]450
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]451 <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]452 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]453 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]454
455 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
456 all target specific attributes.</li>
457
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]458 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
459 Other built-in functions.<br>
460 We support all builtins which have a C language equivalent (e.g.,
461 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
462 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000[diff] [blame]463 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
464 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]465 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
466 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
467 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]468 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]469
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]470 <p>The following extensions <b>are</b> known to be supported:</p>
471
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]472 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]473 <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]474 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
475 <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]476 <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]477 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
478 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
479 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
480 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
481 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
482 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
483 <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>
484 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
485 <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]486 <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]487 <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]488 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
489or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]490 <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]491 <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]492 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
494 <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]495 <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]496 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
497 <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>
498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
500 <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>
501 <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>
502 <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]503 <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]504 <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>
505 <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]506 </ol></li>
507
508</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]509
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]510<p>If you run into GCC extensions which have not been included in any of these
511lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]512
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]513</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]514
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]515<!-- ======================================================================= -->
516<div class="doc_subsection">
517 <a name="c++-fe">Known problems with the C++ front-end</a>
518</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]519
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]520<div class="doc_text">
521
Reid Spencere09ca642004-12-07 08:39:08 +0000[diff] [blame]522<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]523tested and works for a number of non-trivial programs, including LLVM
524itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]525
526</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]527
528<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]529<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]530
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]531<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]532
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]533<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]534<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]535 front-end</a>.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]536
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]537</ul>
538
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]539</div>
540
541<!-- _______________________________________________________________________ -->
542<div class="doc_subsubsection">
543 Notes
544</div>
545
546<div class="doc_text">
547
548<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]549
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]550<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
551parser is significantly more standards compliant (and picky) than prior GCC
552versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]553href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]554
555<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]556 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]557 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]558 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]559 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]560
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]561<li>The LLVM C++ front-end follows the <a
562 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
563 This document, which is not Itanium specific, specifies a standard for name
564 mangling, class layout, v-table layout, RTTI formats, and other C++
565 representation issues. Because we use this API, code generated by the LLVM
566 compilers should be binary compatible with machine code generated by other
567 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
568 <i>However</i>, the exception handling mechanism used by LLVM is very
569 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]570 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]571
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]572</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]573
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]574</div>
575
576<!-- ======================================================================= -->
577<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]578 <a name="c-be">Known problems with the C back-end</a>
579</div>
580
581<div class="doc_text">
582
583<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]584
585<li>The C back-end produces code that violates the ANSI C Type-Based Alias
586Analysis rules. As such, special options may be necessary to compile the code
587(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]588problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]589
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]590<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]591supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]592frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]593
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]594</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]595
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]596</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]597
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]598<!-- ======================================================================= -->
599<div class="doc_subsection">
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]600 <a name="x86-be">Known problems with the X86 back-end</a>
601</div>
602
603<div class="doc_text">
604
605<ul>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]606<li><a href="http://llvm.org/PR566">Memory Mapped I/O Intrinsics do not fence
607memory</a></li>
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]608</ul>
609
610</div>
611
612<!-- ======================================================================= -->
613<div class="doc_subsection">
614 <a name="ppc-be">Known problems with the PowerPC back-end</a>
615</div>
616
617<div class="doc_text">
618
619<ul>
620<li>None yet</li>
621</ul>
622
623</div>
624
625<!-- ======================================================================= -->
626<div class="doc_subsection">
627 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
628</div>
629
630<div class="doc_text">
631
632<ul>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]633<li><a href="http://llvm.org/PR60">[sparcv9] SparcV9 backend miscompiles
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]634several programs in the LLVM test suite</a></li>
635</ul>
636
637</div>
638
639<!-- ======================================================================= -->
640<div class="doc_subsection">
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]641 <a name="alpha-be">Known problems with the Alpha back-end</a>
642</div>
643
644<div class="doc_text">
645
646<ul>
647
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]648<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
649appropriate nops inserted to ensure restartability.</li>
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]650
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]651</ul>
652
653</div>
654
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]655<!-- ======================================================================= -->
656<div class="doc_subsection">
657 <a name="ia64-be">Known problems with the IA64 back-end</a>
658</div>
659
660<div class="doc_text">
661
662<ul>
663
664<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
665made where the argument is not 16-byte aligned, as required on IA64. (Strictly
666speaking this is not a bug in the IA64 back-end; it will also be encountered
667when building C++ programs using the C back-end.)</li>
668
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]669<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]670ABI compliant layout of v-tables</a>. In particular, it just stores function
671pointers instead of function descriptors in the vtable. This bug prevents
672mixing C++ code compiled with LLVM with C++ objects compiled by other C++
673compilers.</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]674
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]675<li>There are a few ABI violations which will lead to problems when mixing LLVM
676output with code built with other compilers, particularly for floating-point
677programs.</li>
678
679<li>Defining vararg functions is not supported (but calling them is ok).</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]680
681</ul>
682
683</div>
684
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]685<!-- ======================================================================= -->
686<div class="doc_subsection">
687 <a name="sparcv8">Known problems with the SPARC-V8 back-end</a>
688</div>
689
690<div class="doc_text">
691
692<ul>
693<li>Many features are still missing (e.g. support for 64-bit integer
Chris Lattnerfeaf9602005-10-29 05:14:01 +0000[diff] [blame]694arithmetic). This back-end is in pre-beta state.</li>
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]695</ul>
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]696</div>
697
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]698<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]699<div class="doc_section">
700 <a name="additionalinfo">Additional Information</a>
701</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]702<!-- *********************************************************************** -->
703
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]704<div class="doc_text">
705
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]706<p>A wide variety of additional information is available on the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]707href="http://llvm.org">LLVM web page</a>, including <a
708href="http://llvm.org/docs/">documentation</a> and <a
709href="http://llvm.org/pubs/">publications describing algorithms and
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]710components implemented in LLVM</a>. The web page also contains versions of the
711API documentation which is up-to-date with the CVS version of the source code.
712You can access versions of these documents specific to this release by going
713into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]714
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]715<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]716us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]717lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]718
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]719</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]720
721<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]722
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]723<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]724<address>
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727 <a href="http://validator.w3.org/check/referer"><img
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729
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]730 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]731 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]732</address>
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]734</body>
735</html>