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Chris Lattner2c3ef982008-10-11 18:18:28 +00007 <title>LLVM 2.4 Release Notes</title>
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9<body>
10
Chris Lattner2c3ef982008-10-11 18:18:28 +000011<div class="doc_title">LLVM 2.4 Release Notes</div>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +000012
Dan Gohmanf17a25c2007-07-18 16:29:46 +000013<ol>
14 <li><a href="#intro">Introduction</a></li>
Chris Lattnerf6a0d382008-06-08 21:58:17 +000015 <li><a href="#changes">Major Changes and Sub-project Status</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +000016 <li><a href="#whatsnew">What's New?</a></li>
17 <li><a href="GettingStarted.html">Installation Instructions</a></li>
18 <li><a href="#portability">Portability and Supported Platforms</a></li>
19 <li><a href="#knownproblems">Known Problems</a>
20 <li><a href="#additionalinfo">Additional Information</a></li>
21</ol>
22
23<div class="doc_author">
24 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
25</div>
26
27<!-- *********************************************************************** -->
28<div class="doc_section">
29 <a name="intro">Introduction</a>
30</div>
31<!-- *********************************************************************** -->
32
33<div class="doc_text">
34
35<p>This document contains the release notes for the LLVM compiler
Chris Lattner2c3ef982008-10-11 18:18:28 +000036infrastructure, release 2.4. Here we describe the status of LLVM, including
Dan Gohmanf17a25c2007-07-18 16:29:46 +000037major improvements from the previous release and any known problems. All LLVM
38releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
39releases web site</a>.</p>
40
41<p>For more information about LLVM, including information about the latest
42release, please check out the <a href="http://llvm.org/">main LLVM
43web site</a>. If you have questions or comments, the <a
44href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
45list</a> is a good place to send them.</p>
46
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +000047<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +000048main LLVM web page, this document applies to the <i>next</i> release, not the
49current one. To see the release notes for a specific releases, please see the
50<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +000051
52</div>
53
54<!-- *********************************************************************** -->
55<div class="doc_section">
Chris Lattnerf6a0d382008-06-08 21:58:17 +000056 <a name="changes">Major Changes and Sub-project Status</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +000057</div>
58<!-- *********************************************************************** -->
59
60<div class="doc_text">
61
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +000062<p>This is the fifteenth public release of the LLVM Compiler Infrastructure.
Chris Lattner2c3ef982008-10-11 18:18:28 +000063It includes a large number of features and refinements from LLVM 2.3.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +000064
65</div>
66
Chris Lattner2c3ef982008-10-11 18:18:28 +000067<!-- Unfinished features in 2.4:
Chris Lattner8fda4952008-02-10 07:46:44 +000068 Machine LICM
69 Machine Sinking
70 LegalizeDAGTypes
Chris Lattner4f076402008-10-12 19:47:48 +000071 llc -enable-value-prop, propagation of value info (sign/zero ext info) from
72 one MBB to another
Chris Lattner8fda4952008-02-10 07:46:44 +000073 -->
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +000074
Chris Lattner4f076402008-10-12 19:47:48 +000075 <!-- for announcement email:
76 mention dev mtg
Chris Lattner548493b2008-10-12 22:57:58 +000077 Xcode 3.1 and 3.1.1.
Chris Lattner4f076402008-10-12 19:47:48 +000078 -->
Chris Lattner8fda4952008-02-10 07:46:44 +000079
Dan Gohmanf17a25c2007-07-18 16:29:46 +000080<!--=========================================================================-->
81<div class="doc_subsection">
Chris Lattner2c3ef982008-10-11 18:18:28 +000082<a name="changes">Major Changes in LLVM 2.4</a>
Chris Lattner41bf8e92008-02-10 07:04:35 +000083</div>
84
85<div class="doc_text">
86
Chris Lattner4f076402008-10-12 19:47:48 +000087<p>The LLVM IR generated by llvm-gcc now doesn't name instructions. Use the
88 instnamer pass if you want them.</p>
89
Chris Lattner548493b2008-10-12 22:57:58 +000090<li>LoadVN and GCSE are completely gone.</li>
Chris Lattner4f076402008-10-12 19:47:48 +000091
Chris Lattnerd95b5962008-06-08 21:19:07 +000092
Chris Lattner0eef6e42008-06-08 02:45:07 +000093<p>LLVM API Changes:</p>
Chris Lattnere45f18b2008-06-05 08:02:49 +000094
Chris Lattner0eef6e42008-06-08 02:45:07 +000095<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +000096<li>....</li>
Daniel Dunbardcb129a2008-10-11 21:26:56 +000097
98<li>... Attributes changes ... </li>
99
Chris Lattnera5a49382008-10-12 18:30:33 +0000100<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
101<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
102converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
103"llvm/Analysis/ValueTracking.h".</li>
Daniel Dunbardcb129a2008-10-11 21:26:56 +0000104
Chris Lattnera5a49382008-10-12 18:30:33 +0000105<li>API change: BinaryOperator::create -> Create (CmpInst, CastInst too)</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000106<li>Various header files like "llvm/ADT/iterator" were given a .h suffix.
107 Change your code to #include "llvm/ADT/iterator.h" instead.</li>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000108
Chris Lattner0eef6e42008-06-08 02:45:07 +0000109</ul>
Chris Lattner548493b2008-10-12 22:57:58 +0000110
Chris Lattnere0798082008-02-06 18:00:06 +0000111</div>
112
113<!--=========================================================================-->
114<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000115<a name="otherprojects">Other LLVM Sub-Projects</a>
116</div>
117
118<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000119<p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000120The core LLVM 2.4 distribution currently consists of code from the core LLVM
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000121repository (which roughly contains the LLVM optimizer, code generators and
122supporting tools) and the llvm-gcc repository. In addition to this code, the
123LLVM Project includes other sub-projects that are in development. The two which
Chris Lattner2c3ef982008-10-11 18:18:28 +0000124are the most actively developed are the <a href="#clang">Clang Project</a> and
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000125<a href="#vmkit">vmkit Project</a>.
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000126</p>
127</div>
128
129<!--=========================================================================-->
130<div class="doc_subsubsection">
131<a name="vmkit">vmkit</a>
132</div>
133
134<div class="doc_text">
135<p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000136The <a href="http://vmkit.llvm.org/">"vmkit" project</a> is an implementation of
137a JVM and a CLI Virtual Machines (Microsoft .NET is an
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000138implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
139
Chris Lattner2c3ef982008-10-11 18:18:28 +0000140<p>...</p>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000141
142</div>
143
144<!--=========================================================================-->
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000145<div class="doc_subsubsection">
146<a name="clang">Clang</a>
147</div>
148
149<div class="doc_text">
150
151<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
152a set of new 'LLVM native' front-end technologies for the LLVM optimizer
153and code generator. Clang is continuing to make major strides forward in all
154areas. Its C and Objective-C parsing support is very solid, and the code
155generation support is far enough along to build many C applications. While not
156yet production quality, it is progressing very nicely. In addition, C++
157front-end work has started to make significant progress.</p>
158
Chris Lattner2c3ef982008-10-11 18:18:28 +0000159<p>Codegen progress/state
160</p>
161
162<p>
163<a href="http://clang.llvm.org/StaticAnalysis.html">static analysis tool</a>
164</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000165
166</div>
167
168
169<!-- *********************************************************************** -->
170<div class="doc_section">
171 <a name="whatsnew">What's New?</a>
172</div>
173<!-- *********************************************************************** -->
174
Chris Lattner5cce7a52008-06-08 22:59:35 +0000175<div class="doc_text">
176
Chris Lattner2c3ef982008-10-11 18:18:28 +0000177<p>LLVM 2.4 includes a huge number of bug fixes, performance tweaks and minor
Chris Lattner5cce7a52008-06-08 22:59:35 +0000178improvements. Some of the major improvements and new features are listed in
179this section.
180</p>
181</div>
182
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000183<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000184<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000185<a name="majorfeatures">Major New Features</a>
186</div>
187
188<div class="doc_text">
189
Chris Lattner2c3ef982008-10-11 18:18:28 +0000190<p>LLVM 2.4 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000191
192<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000193<li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000194 <p>MRVs got generalized to FCAs. getresult is gone, ret with multiple values
195 is gone.</p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000196 </li>
197
Chris Lattner4f076402008-10-12 19:47:48 +0000198<li><p>-O0 compile times overall much faster</p></li>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000199
Chris Lattner2c3ef982008-10-11 18:18:28 +0000200<li><p>Attrs changes?</p></li>
Chris Lattnerba948522008-06-05 06:57:39 +0000201
Chris Lattnera5a49382008-10-12 18:30:33 +0000202
203<li><p>Initial PIC16 port</p></li>
204
Chris Lattner4f076402008-10-12 19:47:48 +0000205<li><p> Support the rest of the atomic __sync builtins</p></li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000206
Chris Lattner2c3ef982008-10-11 18:18:28 +0000207<li><p>...</p></li>
Chris Lattnerba948522008-06-05 06:57:39 +0000208
Chris Lattner5ba16862008-02-10 08:18:42 +0000209</ul>
210
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000211</div>
212
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000213
214<!--=========================================================================-->
215<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000216<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000217</div>
218
219<div class="doc_text">
220
Chris Lattner2c3ef982008-10-11 18:18:28 +0000221<p>LLVM 2.4 fully supports the llvm-gcc 4.2 front-end, and includes support
Chris Lattner5cce7a52008-06-08 22:59:35 +0000222for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000223
Chris Lattner5cce7a52008-06-08 22:59:35 +0000224<p>
225<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000226<li>...</li>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000227
Gabor Greif0e49cc82008-06-09 06:06:18 +0000228</ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000229
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000230</div>
231
232
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000233<!--=========================================================================-->
234<div class="doc_subsection">
Chris Lattnerc3649452008-02-10 08:17:19 +0000235<a name="coreimprovements">LLVM Core Improvements</a>
236</div>
237
238<div class="doc_text">
239<p>New features include:
240</p>
241
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000242<ul>
Chris Lattner548493b2008-10-12 22:57:58 +0000243<li>vector shifts in the IR: no codegen support yet</li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000244<li>use diet patch landed: saved 15% IR memory footprint</li>
245<li>LLVM IR now directly represents "common" linkage, instead of
246 representing it as a form of weak linkage.</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000247<li>DebugInfoBuilder</li>
Chris Lattner548493b2008-10-12 22:57:58 +0000248<li>.ll printing format change: %3 = add i32 4, 2</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000249<li>...</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000250</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000251
Chris Lattnerc3649452008-02-10 08:17:19 +0000252</div>
253
254<!--=========================================================================-->
255<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000256<a name="optimizer">Optimizer Improvements</a>
257</div>
258
259<div class="doc_text">
260
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000261<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner2c3ef982008-10-11 18:18:28 +0000262LLVM 2.4 optimizers support a few major enhancements:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000263
264<ul>
265
Chris Lattner4f076402008-10-12 19:47:48 +0000266<li>GVN now does local PRE?</li>
267
268<li>Matthijs' Dead argument elimination rewrite</li>
269
Chris Lattnera5a49382008-10-12 18:30:33 +0000270<li>Old-ADCE used control dependence and deleted output-free infinite loops.
271Added a new Loop deletion pass (for deleting output free provably-finite loops)
272and rewrote ADCE to be simpler faster, and not need control dependence.</li>
273
274<li>SparsePropagation framework for lattice-based dataflow solvers.</li>
275
Chris Lattner548493b2008-10-12 22:57:58 +0000276<li>Tail duplication was removed from the standard optimizer sequence.</li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000277
Chris Lattner4f076402008-10-12 19:47:48 +0000278<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
279pulled out of instcombine and put into a new ValueTracking.h file, where they
280can be reused by other passes.</li>
281
Chris Lattner548493b2008-10-12 22:57:58 +0000282<li>MarkModRef etc</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000283</ul>
284
285</div>
286
287<!--=========================================================================-->
288<div class="doc_subsection">
289<a name="codegen">Code Generator Improvements</a>
290</div>
291
292<div class="doc_text">
293
294<p>We put a significant amount of work into the code generator infrastructure,
295which allows us to implement more aggressive algorithms and make it run
296faster:</p>
297
298<ul>
Chris Lattner548493b2008-10-12 22:57:58 +0000299<li>asm writers split out to their own library to avoid JITs having to link
300 them in.</li>
301<li>Big asm writer refactoring + TargetAsmInfo</li>
302<li>2-addr pass and coalescer can now remat trivial insts to avoid a copy.</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000303<li>spiller to commute instructions in order to fold a reload</li>
304<li>Stack slot coloring?</li>
305<li>Live intervals renumbering? Is this useful to external people?</li>
306<li>'is as cheap as a move' instruction flag</li>
307<li>Improvements to selection dag viewing</li>
308<li>fast isel</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000309<li>Selection dag speedups</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000310<li>asmwriter + raw_ostream -> fastah</li>
Chris Lattner72c8a252008-10-13 17:12:51 +0000311<li>Partitioned Boolean Quadratic Programming (PBQP) based register
312allocator.</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000313<li>...</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000314
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000315</ul>
316
317</div>
318
319
320<!--=========================================================================-->
321<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000322<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000323</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000324
325<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000326<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000327</p>
328
329<ul>
Chris Lattner4f076402008-10-12 19:47:48 +0000330<li>Exception handling is supported by default on Linux/x86-64.</li>
331<li>Position Independent Code (PIC) is now support on Linux/x86-64.</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000332<li>...</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000333
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000334</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000335
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000336</div>
337
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000338<!--=========================================================================-->
339<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000340<a name="targetspecific">Other Target Specific Improvements</a>
341</div>
342
343<div class="doc_text">
344<p>New target-specific features include:
345</p>
346
347<ul>
Chris Lattner548493b2008-10-12 22:57:58 +0000348<li>MIPS floating point support?</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000349<li>....</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000350</ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000351
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000352</div>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000353
354
355<!--=========================================================================-->
356<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000357<a name="otherimprovements">Other Improvements</a>
358</div>
359
360<div class="doc_text">
361<p>New features include:
362</p>
363
364<ul>
Mikhail Glushenkovcc2d3012008-10-13 02:46:01 +0000365<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000366 support. It is now easier to experiment with <tt>llvmc2</tt> and
367 build your own tools based on it. </li>
Chris Lattner4f076402008-10-12 19:47:48 +0000368<li>raw_ostream + formatting</li>
Chris Lattner548493b2008-10-12 22:57:58 +0000369<li>Recycler + pool allocation stuff?</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000370<li>...</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000371</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000372
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000373</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000374
375<!-- *********************************************************************** -->
376<div class="doc_section">
377 <a name="portability">Portability and Supported Platforms</a>
378</div>
379<!-- *********************************************************************** -->
380
381<div class="doc_text">
382
383<p>LLVM is known to work on the following platforms:</p>
384
385<ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000386<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000387 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000388<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000389 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000390<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000391<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
392 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000393<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000394<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000395<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000396</ul>
397
Chris Lattnerba948522008-06-05 06:57:39 +0000398<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000399to the machine and operating system on which it is built. However, minor
400porting may be required to get LLVM to work on new platforms. We welcome your
401portability patches and reports of successful builds or error messages.</p>
402
403</div>
404
405<!-- *********************************************************************** -->
406<div class="doc_section">
407 <a name="knownproblems">Known Problems</a>
408</div>
409<!-- *********************************************************************** -->
410
411<div class="doc_text">
412
413<p>This section contains all known problems with the LLVM system, listed by
414component. As new problems are discovered, they will be added to these
415sections. If you run into a problem, please check the <a
416href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
417there isn't already one.</p>
418
419</div>
420
421<!-- ======================================================================= -->
422<div class="doc_subsection">
423 <a name="experimental">Experimental features included with this release</a>
424</div>
425
426<div class="doc_text">
427
428<p>The following components of this LLVM release are either untested, known to
429be broken or unreliable, or are in early development. These components should
430not be relied on, and bugs should not be filed against them, but they may be
431useful to some people. In particular, if you would like to work on one of these
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000432components, please contact us on the <a
433href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000434
435<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000436<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000437<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattnerbd633de92008-02-06 06:30:34 +0000438 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000439</ul>
440
441</div>
442
443<!-- ======================================================================= -->
444<div class="doc_subsection">
445 <a name="x86-be">Known problems with the X86 back-end</a>
446</div>
447
448<div class="doc_text">
449
450<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000451 <li>The X86 backend does not yet support
452 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
453 floating point stack</a>. It supports the 'f' and 't' constraints, but not
454 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000455 <li>The X86 backend generates inefficient floating point code when configured
456 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000457 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000458 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
459 currently due
460 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000461 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
462 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000463 <li>The X86-64 backend does not yet support the LLVM IR instruction
464 <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
465 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000466</ul>
467
468</div>
469
470<!-- ======================================================================= -->
471<div class="doc_subsection">
472 <a name="ppc-be">Known problems with the PowerPC back-end</a>
473</div>
474
475<div class="doc_text">
476
477<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000478<li>The Linux PPC32/ABI support needs testing for the interpreter and static
479compilation, and lacks support for debug information.</li>
480</ul>
481
482</div>
483
484<!-- ======================================================================= -->
485<div class="doc_subsection">
486 <a name="arm-be">Known problems with the ARM back-end</a>
487</div>
488
489<div class="doc_text">
490
491<ul>
492<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000493processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000494results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
495<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
496</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000497<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
498 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000499programs compiled with LLVM. Please use more recent versions of QEMU.</li>
500</ul>
501
502</div>
503
504<!-- ======================================================================= -->
505<div class="doc_subsection">
506 <a name="sparc-be">Known problems with the SPARC back-end</a>
507</div>
508
509<div class="doc_text">
510
511<ul>
512<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
513 support the 64-bit SPARC ABI (-m64).</li>
514</ul>
515
516</div>
517
518<!-- ======================================================================= -->
519<div class="doc_subsection">
520 <a name="alpha-be">Known problems with the Alpha back-end</a>
521</div>
522
523<div class="doc_text">
524
525<ul>
526
527<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
528appropriate nops inserted to ensure restartability.</li>
529
530</ul>
531</div>
532
533<!-- ======================================================================= -->
534<div class="doc_subsection">
535 <a name="ia64-be">Known problems with the IA64 back-end</a>
536</div>
537
538<div class="doc_text">
539
540<ul>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000541<li>The Itanium backend is highly experimental, and has a number of known
542 issues. We are looking for a maintainer for the Itanium backend. If you
543 are interested, please contact the llvmdev mailing list.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000544</ul>
545
546</div>
547
548<!-- ======================================================================= -->
549<div class="doc_subsection">
550 <a name="c-be">Known problems with the C back-end</a>
551</div>
552
553<div class="doc_text">
554
555<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000556<li><a href="http://llvm.org/PR802">The C backend has only basic support for
557 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000558<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
559 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sandsa73561c2008-06-08 20:18:35 +0000560 C++ code compiled with llc or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000561<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000562</ul>
563
564</div>
565
566
567<!-- ======================================================================= -->
568<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000569 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000570</div>
571
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000572<div class="doc_text">
573
Chris Lattnere0798082008-02-06 18:00:06 +0000574<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
575Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000576llvmdev mailing list if you are interested.</p>
577
Chris Lattner499c07c2008-06-05 06:35:40 +0000578<p>The only major language feature of GCC not supported by llvm-gcc is
579 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
580 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000581 supported on some targets (these are used when you take the address of a
582 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000583
Chris Lattner499c07c2008-06-05 06:35:40 +0000584<p>If you run into GCC extensions which are not supported, please let us know.
585</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000586
587</div>
588
589<!-- ======================================================================= -->
590<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000591 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000592</div>
593
594<div class="doc_text">
595
596<p>The C++ front-end is considered to be fully
597tested and works for a number of non-trivial programs, including LLVM
598itself, Qt, Mozilla, etc.</p>
599
600<ul>
Anton Korobeynikovd9a17932008-10-11 18:27:16 +0000601<li>Exception handling works well on the X86 and PowerPC targets. Currently
602 only linux and darwin targets are supported (both 32 and 64 bit).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000603</ul>
604
605</div>
606
607
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000608<!-- ======================================================================= -->
609<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000610 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000611</div>
612
613<div class="doc_text">
614The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
615technology and problems should be expected.
616<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000617<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000618to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sandsa73561c2008-06-08 20:18:35 +0000619however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000620which does support trampolines.</li>
621<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
622Workaround: configure with --disable-bootstrap.</li>
623<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
Duncan Sandsa73561c2008-06-08 20:18:35 +0000624fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
625<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
626<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
627reports most tests as having failed even though they pass.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000628<li>The -E binder option (exception backtraces)
629<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
630crashing if an exception is raised. Workaround: do not use -E.</li>
631<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
632or finish at a non-byte offset</a> in a record. Workaround: do not pack records
633or use representation clauses that result in a field of a non-discrete type
634starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000635<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
636'main' as generated by the Ada binder to be invalid</a>.
637Workaround: hand edit the file to use pointers for <tt>argv</tt> and
638<tt>envp</tt> rather than integers.</li>
639<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
640ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000641</ul>
642</div>
643
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000644<!-- *********************************************************************** -->
645<div class="doc_section">
646 <a name="additionalinfo">Additional Information</a>
647</div>
648<!-- *********************************************************************** -->
649
650<div class="doc_text">
651
652<p>A wide variety of additional information is available on the <a
653href="http://llvm.org">LLVM web page</a>, in particular in the <a
654href="http://llvm.org/docs/">documentation</a> section. The web page also
655contains versions of the API documentation which is up-to-date with the
656Subversion version of the source code.
657You can access versions of these documents specific to this release by going
658into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
659
660<p>If you have any questions or comments about LLVM, please feel free to contact
661us via the <a href="http://llvm.org/docs/#maillist"> mailing
662lists</a>.</p>
663
664</div>
665
666<!-- *********************************************************************** -->
667
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