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gerrit-public.fairphone.software / toolchain / llvm-project / 0b7fd71e1c1f31d20df99a0e188b8f2d724a9c10 / . / llvm / docs / ReleaseNotes.html
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Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]7 <title>LLVM 1.7 Release Notes</title>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]10
Chris Lattner578ab912005-11-08 21:29:17 +0000[diff] [blame]11<div class="doc_title">LLVM 1.7 Release Notes</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]12
13<ol>
Misha Brukman80731b92003-11-22 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 Lattner77a51732004-04-30 22:17:12 +0000[diff] [blame]16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]18 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]20</ol>
21
Chris Lattner020e1fc2004-05-23 21:07:27 +0000[diff] [blame]22<div class="doc_author">
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]24</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]25
26<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]27<div class="doc_section">
28 <a name="intro">Introduction</a>
29</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]30<!-- *********************************************************************** -->
31
Misha Brukman80731b92003-11-22 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 Lattner578ab912005-11-08 21:29:17 +0000[diff] [blame]35infrastructure, release 1.7. Here we describe the status of LLVM, including any
Chris Lattner406bddf2005-05-15 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 Lattner578ab912005-11-08 21:29:17 +0000[diff] [blame]38href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]39not reading this on the LLVM web pages, you should probably go there because
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]40this document may be updated after the release.</p>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]41
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]42<p>For more information about LLVM, including information about the latest
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]43release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattnere7525b52003-10-07 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]46list</a> is a good place to send them.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]47
Chris Lattnerf3a7c242004-12-09 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 Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]51href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]52
53</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]54
55<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]56<div class="doc_section">
57 <a name="whatsnew">What's New?</a>
58</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]59<!-- *********************************************************************** -->
60
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]61<div class="doc_text">
62
Chris Lattner9f871732006-04-18 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 Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]69
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]70</div>
71
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]72<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]73<div class="doc_subsection">
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]74<a name="newfeatures">New Features in LLVM 1.7</a>
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]75</div>
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]76
Chris Lattner9f871732006-04-18 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 Lattner0b7fd712006-04-19 04:02:47 +0000[diff] [blame^]90correspond to GCC's (they emit native code), and it has debugging support well
91underway.</p>
Chris Lattner9f871732006-04-18 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 Lattner89e761c2006-04-18 06:32:08 +0000[diff] [blame]175<!--_________________________________________________________________________-->
Chris Lattner0b7fd712006-04-19 04:02:47 +0000[diff] [blame^]176<div class="doc_subsubsection"><a name="optimizernew">Optimizer
Chris Lattner89e761c2006-04-18 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 Lattner0b7fd712006-04-19 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 Lattner89e761c2006-04-18 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 Lattner0b7fd712006-04-19 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 Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]223
224<!--_________________________________________________________________________-->
225<div class="doc_subsubsection"><a name="othernew">Other New Features</a></div>
226
Chris Lattnera38fe5f2006-02-05 06:39:36 +0000[diff] [blame]227<div class="doc_text">
228<ul>
Chris Lattner0b7fd712006-04-19 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 Lattner89e761c2006-04-18 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 Lattner0b7fd712006-04-19 04:02:47 +0000[diff] [blame^]240 significantly easier.</li>
Chris Lattner89e761c2006-04-18 06:32:08 +0000[diff] [blame]241<li>llvmgcc4 now fully supports C99 Variable Length Arrays, including dynamic
242 stack deallocation.</li>
243
Chris Lattnera38fe5f2006-02-05 06:39:36 +0000[diff] [blame]244</ul>
245</div>
John Criswell51e2a482005-06-29 16:22:34 +0000[diff] [blame]246
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]247
Chris Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]248<!--=========================================================================-->
249<div class="doc_subsection">
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]250<a name="changes">Significant Changes in LLVM 1.7</a>
Chris Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]251</div>
252
253<div class="doc_text">
254<ul>
Chris Lattner0b7fd712006-04-19 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 Lattner9f871732006-04-18 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 Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]274</ul>
275</div>
276
277
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]278<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]279<div class="doc_section">
280 <a name="portability">Portability and Supported Platforms</a>
281</div>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]282<!-- *********************************************************************** -->
283
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]284<div class="doc_text">
285
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]286<p>LLVM is known to work on the following platforms:</p>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]287
288<ul>
Reid Spencer9803b402005-05-17 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 Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]291<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattnerb5bb5972004-12-07 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 Lattner8ad30362005-10-29 05:14:01 +0000[diff] [blame]294<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above.</li>
John Criswelld5234922005-05-13 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 Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]297</ul>
298
Brian Gaekee3e557e2004-05-09 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]304
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]305</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]306
307<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]308<div class="doc_section">
309 <a name="knownproblems">Known Problems</a>
310</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]311<!-- *********************************************************************** -->
312
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]316component. As new problems are discovered, they will be added to these
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]317sections. If you run into a problem, please check the <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]318href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]319there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]320
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]321</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]322
Chris Lattnerb911de42004-03-14 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]327
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]328<div class="doc_text">
329
Misha Brukmanfa50a222004-05-12 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 Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]335
336<ul>
Chris Lattner9f871732006-04-18 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 Lattnera38fe5f2006-02-05 06:39:36 +0000[diff] [blame]339<li>The IA64 code generator is experimental.</li>
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]340<li>The Alpha JIT is experimental.</li>
Chris Lattner9f871732006-04-18 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 Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]343</ul>
344
345</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]346
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]347<!-- ======================================================================= -->
348<div class="doc_subsection">
John Criswell3bdbd302005-11-08 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]362 <a name="core">Known problems with the LLVM Core</a>
363</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]364
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]365<div class="doc_text">
366
367<ul>
Misha Brukman96158092005-03-30 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]370</ul>
Misha Brukman80731b92003-11-22 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 Lattner178f3db2003-10-02 05:07:23 +0000[diff] [blame]377
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]378<!-- _______________________________________________________________________ -->
Chris Lattner5a8a7282003-12-14 05:03:43 +0000[diff] [blame]379<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]380
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]381<div class="doc_text">
Chris Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]382
Chris Lattner9f871732006-04-18 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>.
386Two signicant ones include:</p>
Chris Lattner72a269f2006-03-03 00:34:26 +0000[diff] [blame]387
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]388<ul>
Chris Lattner9f871732006-04-18 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]397</pre></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]398
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]399<li>With llvm-gcc3, Initialization of global union variables can only be done <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]400href="http://llvm.org/PR162">with the largest union member</a>.</li>
Chris Lattner1ab58dd2004-03-16 21:39:04 +0000[diff] [blame]401
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]402</ul>
Misha Brukman80731b92003-11-22 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 Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]414<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 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 Brukman80731b92003-11-22 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 Criswell86a3a482003-12-18 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 Brukman80731b92003-11-22 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 Brukman80731b92003-11-22 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 Lattner63371342004-12-08 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 Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]442 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]443
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]444 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner3d482502003-10-02 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 Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]447 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]448 the program.</p>
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]453 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]456
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]457 Declaring that functions have no side effects or that they can never
Misha Brukman80731b92003-11-22 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 Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]461 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Chris Lattnerca18d192005-12-05 05:23:06 +0000[diff] [blame]462 <tt>unused</tt>, <tt>used</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]463 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
464
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]465 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman80731b92003-11-22 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 Lattnerca18d192005-12-05 05:23:06 +0000[diff] [blame]469 <b>Unsupported:</b> <tt>section</tt>, <tt>alias</tt>,
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Lattnerca18d192005-12-05 05:23:06 +0000[diff] [blame]477 <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]478
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]482 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]483
Misha Brukman8395d732003-12-12 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]485 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]486 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Lattnerb7c4bac2004-06-18 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 Lattnerb34b2732005-05-07 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]501 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]502
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]503 <p>The following extensions <b>are</b> known to be supported:</p>
504
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]505 <ol>
Chris Lattnerd3dc8502004-03-16 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 Brukman80731b92003-11-22 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 Lattnerce33a1b2004-06-22 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 Brukman80731b92003-11-22 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 Brukman8395d732003-12-12 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 Brukman80731b92003-11-22 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 Criswell86a3a482003-12-18 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 Brukman80731b92003-11-22 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 Brukman8395d732003-12-12 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 Brukman80731b92003-11-22 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 Lattner7591b822004-12-08 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 Brukman80731b92003-11-22 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 Lattner3646dad2004-02-14 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 Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]539 </ol></li>
540
541</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]542
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]545
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]546</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]547
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]552
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]553<div class="doc_text">
554
Reid Spencer55684c32004-12-07 08:39:08 +0000[diff] [blame]555<p>For this release, the C++ front-end is considered to be fully
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]556tested and works for a number of non-trivial programs, including LLVM
557itself.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]558
559</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]560
561<!-- _______________________________________________________________________ -->
Chris Lattner141ebb62004-02-14 04:12:41 +0000[diff] [blame]562<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]563
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]564<div class="doc_text">
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]565
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]566<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]567<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]568 front-end</a>.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]569
Chris Lattner5cd40922004-08-02 20:28:44 +0000[diff] [blame]570</ul>
571
Misha Brukman80731b92003-11-22 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 Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]582
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]583<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]584 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]585 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]586 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]587 better than most compilers).</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]588
Chris Lattner62495762003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]598 interact correctly</b>. </li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]599
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]600</ul>
Chris Lattner46ecf612003-10-07 22:14:37 +0000[diff] [blame]601
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]602</div>
603
604<!-- ======================================================================= -->
605<div class="doc_subsection">
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]616problem probably cannot be fixed.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]617
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]618<li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]619supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]620frontends.</li>
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]621
Chris Lattner9f871732006-04-18 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]628</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]629
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]630</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]631
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]632<!-- ======================================================================= -->
633<div class="doc_subsection">
Chris Lattner683a8472005-05-16 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 Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]640<li><a href="http://llvm.org/PR736">Indirect calls crash JIT on
641Darwin/x86</a>.</li>
Chris Lattner683a8472005-05-16 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 Lattner9f871732006-04-18 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 Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame]656</ul>
657
658</div>
659
660<!-- ======================================================================= -->
661<div class="doc_subsection">
Andrew Lenharth2e18c622005-05-03 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 Lattner683a8472005-05-16 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 Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]671
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]672</ul>
673
674</div>
675
Duraid Madina9a449002005-05-14 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 Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]690<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
Chris Lattner683a8472005-05-16 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 Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]695
Chris Lattner683a8472005-05-16 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 Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]701
702</ul>
703
704</div>
705
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]706<!-- ======================================================================= -->
707<div class="doc_subsection">
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]708 <a name="sparc-be">Known problems with the SPARC back-end</a>
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]709</div>
710
711<div class="doc_text">
712
713<ul>
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]714<li>None yet</li>
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]715</ul>
Chris Lattner9f871732006-04-18 06:18:36 +0000[diff] [blame]716
717</div>
718
719
720<!-- ======================================================================= -->
721<div class="doc_subsection">
722 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
723</div>
724
725<div class="doc_text">
726
727<ul>
728<li><a href="http://llvm.org/PR60">[sparcv9] SparcV9 backend miscompiles
729several programs in the LLVM test suite</a></li>
730<li>The SparcV9 backend is slated to be removed before the LLVM 1.8
731 release.</li>
732</ul>
733
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]734</div>
735
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]736<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]737<div class="doc_section">
738 <a name="additionalinfo">Additional Information</a>
739</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]740<!-- *********************************************************************** -->
741
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]742<div class="doc_text">
743
Chris Lattnercb5596d2005-05-16 17:13:10 +0000[diff] [blame]744<p>A wide variety of additional information is available on the <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]745href="http://llvm.org">LLVM web page</a>, including <a
746href="http://llvm.org/docs/">documentation</a> and <a
747href="http://llvm.org/pubs/">publications describing algorithms and
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]748components implemented in LLVM</a>. The web page also contains versions of the
749API documentation which is up-to-date with the CVS version of the source code.
750You can access versions of these documents specific to this release by going
751into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]752
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]753<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]754us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]755lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]756
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]757</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]758
759<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]760
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]761<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]762<address>
Misha Brukman8834af92003-12-21 22:53:21 +0000[diff] [blame]763 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]764 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
765 <a href="http://validator.w3.org/check/referer"><img
766 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
767
Chris Lattnera69595e2005-10-29 07:07:09 +0000[diff] [blame]768 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]769 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]770</address>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]771
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]772</body>
773</html>