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Chris Lattner857fb132008-10-11 18:18:28 +00007 <title>LLVM 2.4 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +00008</head>
9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +000010
Chris Lattner857fb132008-10-11 18:18:28 +000011<div class="doc_title">LLVM 2.4 Release Notes</div>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000012
Chris Lattner79c3fe12003-10-02 04:57:28 +000013<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000014 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +000015 <li><a href="#subproj">Sub-project Status Update</a></li>
16 <li><a href="#whatsnew">What's New in LLVM?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +000017 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +000018 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000019 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +000020 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000021</ol>
22
Chris Lattner7911ce22004-05-23 21:07:27 +000023<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +000024 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +000025</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000026
27<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +000028<div class="doc_section">
29 <a name="intro">Introduction</a>
30</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000031<!-- *********************************************************************** -->
32
Misha Brukman500bc302003-11-22 00:38:41 +000033<div class="doc_text">
34
Chris Lattnerf6662f92008-10-13 17:57:36 +000035<p>This document contains the release notes for the LLVM Compiler
36Infrastructure, release 2.4. Here we describe the status of LLVM, including
37major improvements from the previous release and significant known problems.
38All LLVM releases may be downloaded from the <a
39href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +000040
Chris Lattner7506b1d2004-12-07 08:04:13 +000041<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000042release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000043web site</a>. If you have questions or comments, the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +000044href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
45List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000046
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000047<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 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>
Misha Brukman500bc302003-11-22 00:38:41 +000051
52</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000053
Chris Lattner857fb132008-10-11 18:18:28 +000054<!-- Unfinished features in 2.4:
Chris Lattneracce85d2008-02-10 07:46:44 +000055 Machine LICM
56 Machine Sinking
57 LegalizeDAGTypes
Chris Lattner547a3912008-10-12 19:47:48 +000058 llc -enable-value-prop, propagation of value info (sign/zero ext info) from
59 one MBB to another
Chris Lattneracce85d2008-02-10 07:46:44 +000060 -->
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000061
Chris Lattner547a3912008-10-12 19:47:48 +000062 <!-- for announcement email:
63 mention dev mtg
Chris Lattnercdb0e4c2008-10-12 22:57:58 +000064 Xcode 3.1 and 3.1.1.
Chris Lattner547a3912008-10-12 19:47:48 +000065 -->
Chris Lattneracce85d2008-02-10 07:46:44 +000066
Chris Lattner96a445e2008-10-13 18:01:01 +000067<!-- *********************************************************************** -->
68<div class="doc_section">
69 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerea34f642008-06-08 21:34:41 +000070</div>
Chris Lattner96a445e2008-10-13 18:01:01 +000071<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +000072
73<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +000074<p>
Chris Lattner96a445e2008-10-13 18:01:01 +000075The LLVM 2.4 distribution currently consists of code from the core LLVM
76repository (which roughly contains the LLVM optimizers, code generators and
Chris Lattner8348b472008-06-08 21:58:17 +000077supporting tools) and the llvm-gcc repository. In addition to this code, the
78LLVM Project includes other sub-projects that are in development. The two which
Chris Lattner857fb132008-10-11 18:18:28 +000079are the most actively developed are the <a href="#clang">Clang Project</a> and
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000080<a href="#vmkit">vmkit Project</a>.
Chris Lattner8348b472008-06-08 21:58:17 +000081</p>
Chris Lattner96a445e2008-10-13 18:01:01 +000082
Chris Lattner8348b472008-06-08 21:58:17 +000083</div>
84
Chris Lattner96a445e2008-10-13 18:01:01 +000085
Chris Lattner8348b472008-06-08 21:58:17 +000086<!--=========================================================================-->
Chris Lattner96a445e2008-10-13 18:01:01 +000087<div class="doc_subsection">
Chris Lattner8348b472008-06-08 21:58:17 +000088<a name="clang">Clang</a>
89</div>
90
91<div class="doc_text">
92
93<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
94a set of new 'LLVM native' front-end technologies for the LLVM optimizer
95and code generator. Clang is continuing to make major strides forward in all
96areas. Its C and Objective-C parsing support is very solid, and the code
97generation support is far enough along to build many C applications. While not
98yet production quality, it is progressing very nicely. In addition, C++
99front-end work has started to make significant progress.</p>
100
Chris Lattner857fb132008-10-11 18:18:28 +0000101<p>Codegen progress/state
102</p>
103
104<p>
105<a href="http://clang.llvm.org/StaticAnalysis.html">static analysis tool</a>
106</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000107
108</div>
109
Chris Lattner96a445e2008-10-13 18:01:01 +0000110<!--=========================================================================-->
111<div class="doc_subsection">
112<a name="vmkit">vmkit</a>
113</div>
114
115<div class="doc_text">
116<p>
117The <a href="http://vmkit.llvm.org/">"vmkit" project</a> is an implementation of
118a JVM and a CLI Virtual Machines (Microsoft .NET is an
119implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
120
121<p>...</p>
122
123</div>
124
Chris Lattner8348b472008-06-08 21:58:17 +0000125
126<!-- *********************************************************************** -->
127<div class="doc_section">
Chris Lattner96a445e2008-10-13 18:01:01 +0000128 <a name="whatsnew">What's New in LLVM?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000129</div>
130<!-- *********************************************************************** -->
131
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000132<div class="doc_text">
133
Chris Lattnerf6662f92008-10-13 17:57:36 +0000134<p>This release includes a huge number of bug fixes, performance tweaks and
135minor improvements. Some of the major improvements and new features are listed
136in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000137</p>
138</div>
139
Chris Lattner8348b472008-06-08 21:58:17 +0000140<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000141<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000142<a name="majorfeatures">Major New Features</a>
143</div>
144
145<div class="doc_text">
146
Chris Lattner857fb132008-10-11 18:18:28 +0000147<p>LLVM 2.4 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000148
149<ul>
Chris Lattner857fb132008-10-11 18:18:28 +0000150<li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000151 <p>MRVs got generalized to FCAs. getresult is gone, ret with multiple values
152 is gone.</p>
Chris Lattner857fb132008-10-11 18:18:28 +0000153 </li>
154
Chris Lattner547a3912008-10-12 19:47:48 +0000155<li><p>-O0 compile times overall much faster</p></li>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000156
Chris Lattner857fb132008-10-11 18:18:28 +0000157<li><p>Attrs changes?</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000158
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000159
160<li><p>Initial PIC16 port</p></li>
161
Chris Lattner547a3912008-10-12 19:47:48 +0000162<li><p> Support the rest of the atomic __sync builtins</p></li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000163
Chris Lattner857fb132008-10-11 18:18:28 +0000164<li><p>...</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000165
Chris Lattner8170c102008-02-10 08:18:42 +0000166</ul>
167
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000168</div>
169
Chris Lattner791f77b2008-06-05 06:25:56 +0000170
171<!--=========================================================================-->
172<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000173<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattner791f77b2008-06-05 06:25:56 +0000174</div>
175
176<div class="doc_text">
177
Chris Lattner857fb132008-10-11 18:18:28 +0000178<p>LLVM 2.4 fully supports the llvm-gcc 4.2 front-end, and includes support
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000179for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattner791f77b2008-06-05 06:25:56 +0000180
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000181<p>
182<ul>
Chris Lattner857fb132008-10-11 18:18:28 +0000183<li>...</li>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000184
Gabor Greifa3bd11d2008-06-09 06:06:18 +0000185</ul>
Chris Lattner791f77b2008-06-05 06:25:56 +0000186
Chris Lattner791f77b2008-06-05 06:25:56 +0000187</div>
188
189
Chris Lattner84977642007-09-21 03:54:09 +0000190<!--=========================================================================-->
191<div class="doc_subsection">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000192<a name="coreimprovements">LLVM Core Improvements</a>
193</div>
194
195<div class="doc_text">
196<p>New features include:
197</p>
198
Chris Lattner791f77b2008-06-05 06:25:56 +0000199<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000200<li>vector shifts in the IR: no codegen support yet</li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000201<li>use diet patch landed: saved 15% IR memory footprint</li>
202<li>LLVM IR now directly represents "common" linkage, instead of
203 representing it as a form of weak linkage.</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000204<li>DebugInfoBuilder</li>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000205<li>.ll printing format change: %3 = add i32 4, 2</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000206<li>...</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000207</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000208
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000209</div>
210
211<!--=========================================================================-->
212<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000213<a name="optimizer">Optimizer Improvements</a>
214</div>
215
216<div class="doc_text">
217
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000218<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner857fb132008-10-11 18:18:28 +0000219LLVM 2.4 optimizers support a few major enhancements:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000220
221<ul>
222
Chris Lattner547a3912008-10-12 19:47:48 +0000223<li>GVN now does local PRE?</li>
224
225<li>Matthijs' Dead argument elimination rewrite</li>
226
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000227<li>Old-ADCE used control dependence and deleted output-free infinite loops.
228Added a new Loop deletion pass (for deleting output free provably-finite loops)
229and rewrote ADCE to be simpler faster, and not need control dependence.</li>
230
231<li>SparsePropagation framework for lattice-based dataflow solvers.</li>
232
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000233<li>Tail duplication was removed from the standard optimizer sequence.</li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000234
Chris Lattner547a3912008-10-12 19:47:48 +0000235<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
236pulled out of instcombine and put into a new ValueTracking.h file, where they
237can be reused by other passes.</li>
238
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000239<li>MarkModRef etc</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000240</ul>
241
242</div>
243
244<!--=========================================================================-->
245<div class="doc_subsection">
246<a name="codegen">Code Generator Improvements</a>
247</div>
248
249<div class="doc_text">
250
251<p>We put a significant amount of work into the code generator infrastructure,
252which allows us to implement more aggressive algorithms and make it run
253faster:</p>
254
255<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000256<li>asm writers split out to their own library to avoid JITs having to link
257 them in.</li>
258<li>Big asm writer refactoring + TargetAsmInfo</li>
259<li>2-addr pass and coalescer can now remat trivial insts to avoid a copy.</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000260<li>spiller to commute instructions in order to fold a reload</li>
261<li>Stack slot coloring?</li>
262<li>Live intervals renumbering? Is this useful to external people?</li>
263<li>'is as cheap as a move' instruction flag</li>
264<li>Improvements to selection dag viewing</li>
265<li>fast isel</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000266<li>Selection dag speedups</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000267<li>asmwriter + raw_ostream -> fastah</li>
Chris Lattner59b5ce42008-10-13 17:12:51 +0000268<li>Partitioned Boolean Quadratic Programming (PBQP) based register
269allocator.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000270<li>...</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000271
Chris Lattner84977642007-09-21 03:54:09 +0000272</ul>
273
274</div>
275
276
277<!--=========================================================================-->
278<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000279<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattner84977642007-09-21 03:54:09 +0000280</div>
Chris Lattner60893e52007-05-18 06:33:02 +0000281
Chris Lattner738bd302006-04-18 06:32:08 +0000282<div class="doc_text">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000283<p>New target-specific features include:
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000284</p>
Chris Lattner26299222006-11-18 07:51:14 +0000285
286<ul>
Chris Lattner547a3912008-10-12 19:47:48 +0000287<li>Exception handling is supported by default on Linux/x86-64.</li>
Duncan Sandsbbf379a2008-10-13 17:32:15 +0000288<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000289<li>...</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000290
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000291</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000292
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000293</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000294
Chris Lattner84977642007-09-21 03:54:09 +0000295<!--=========================================================================-->
296<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000297<a name="targetspecific">Other Target Specific Improvements</a>
298</div>
299
300<div class="doc_text">
301<p>New target-specific features include:
302</p>
303
304<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000305<li>MIPS floating point support?</li>
Duncan Sandsbbf379a2008-10-13 17:32:15 +0000306<li>PowerPC now supports trampolines.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000307<li>....</li>
Chris Lattner77d29b12008-06-05 08:02:49 +0000308</ul>
Chris Lattner77d29b12008-06-05 08:02:49 +0000309
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000310</div>
Chris Lattner77d29b12008-06-05 08:02:49 +0000311
312
313<!--=========================================================================-->
314<div class="doc_subsection">
Chris Lattner84977642007-09-21 03:54:09 +0000315<a name="otherimprovements">Other Improvements</a>
316</div>
317
318<div class="doc_text">
319<p>New features include:
320</p>
321
322<ul>
Mikhail Glushenkov49feb452008-10-13 02:46:01 +0000323<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000324 support. It is now easier to experiment with <tt>llvmc2</tt> and
325 build your own tools based on it. </li>
Chris Lattner547a3912008-10-12 19:47:48 +0000326<li>raw_ostream + formatting</li>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000327<li>Recycler + pool allocation stuff?</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000328<li>...</li>
Chris Lattner84977642007-09-21 03:54:09 +0000329</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000330
Chris Lattner84977642007-09-21 03:54:09 +0000331</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000332
Chris Lattnerf6662f92008-10-13 17:57:36 +0000333<!--=========================================================================-->
334<div class="doc_subsection">
335<a name="changes">Major Changes and Removed Features</a>
336</div>
337
338<div class="doc_text">
339
Chris Lattner96a445e2008-10-13 18:01:01 +0000340<p>If you're already an LLVM user, this section lists some "gotchas" that you
341may run into upgrading from the previous release.</p>
342
Chris Lattnerf6662f92008-10-13 17:57:36 +0000343<p>The LLVM IR generated by llvm-gcc now doesn't name instructions. Use the
344 instnamer pass if you want them.</p>
345
346<li>LoadVN and GCSE are completely gone.</li>
347
348
349<p>LLVM API Changes:</p>
350
351<ul>
352
353<li>... Attributes changes ... </li>
354
355<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
356<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
357converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
358"llvm/Analysis/ValueTracking.h".</li>
359
360<li>API change: BinaryOperator::create -> Create (CmpInst, CastInst too)</li>
361<li>Various header files like "llvm/ADT/iterator" were given a .h suffix.
362 Change your code to #include "llvm/ADT/iterator.h" instead.</li>
363
364</ul>
365
366</div>
367
368
369
Chris Lattner19092612003-10-02 16:38:05 +0000370<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000371<div class="doc_section">
372 <a name="portability">Portability and Supported Platforms</a>
373</div>
Chris Lattner19092612003-10-02 16:38:05 +0000374<!-- *********************************************************************** -->
375
Misha Brukman500bc302003-11-22 00:38:41 +0000376<div class="doc_text">
377
John Criswell0b5b5e92004-12-08 20:35:47 +0000378<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000379
380<ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000381<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000382 (and probably other unix-like systems).</li>
Chris Lattner000c73b2008-02-06 06:30:34 +0000383<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
Chris Lattner26299222006-11-18 07:51:14 +0000384 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000385<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000386<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
387 support is available for native builds with Visual C++).</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000388<li>Sun UltraSPARC workstations running Solaris 10.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000389<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000390<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000391</ul>
392
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000393<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000394to the machine and operating system on which it is built. However, minor
395porting may be required to get LLVM to work on new platforms. We welcome your
396portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000397
Misha Brukman500bc302003-11-22 00:38:41 +0000398</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000399
400<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000401<div class="doc_section">
402 <a name="knownproblems">Known Problems</a>
403</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000404<!-- *********************************************************************** -->
405
Misha Brukman500bc302003-11-22 00:38:41 +0000406<div class="doc_text">
407
408<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000409component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000410sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000411href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000412there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000413
Misha Brukman500bc302003-11-22 00:38:41 +0000414</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000415
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000416<!-- ======================================================================= -->
417<div class="doc_subsection">
418 <a name="experimental">Experimental features included with this release</a>
419</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000420
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000421<div class="doc_text">
422
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000423<p>The following components of this LLVM release are either untested, known to
424be broken or unreliable, or are in early development. These components should
425not be relied on, and bugs should not be filed against them, but they may be
426useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000427components, please contact us on the <a
428href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000429
430<ul>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000431<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sands27aff872008-06-08 20:18:35 +0000432<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattner000c73b2008-02-06 06:30:34 +0000433 value for this option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000434</ul>
435
436</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000437
Misha Brukman500bc302003-11-22 00:38:41 +0000438<!-- ======================================================================= -->
439<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000440 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000441</div>
442
443<div class="doc_text">
444
445<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000446 <li>The X86 backend does not yet support
447 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
448 floating point stack</a>. It supports the 'f' and 't' constraints, but not
449 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000450 <li>The X86 backend generates inefficient floating point code when configured
451 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000452 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000453 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
454 currently due
455 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000456 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
457 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000458 <li>The X86-64 backend does not yet support the LLVM IR instruction
459 <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
460 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000461</ul>
462
463</div>
464
465<!-- ======================================================================= -->
466<div class="doc_subsection">
467 <a name="ppc-be">Known problems with the PowerPC back-end</a>
468</div>
469
470<div class="doc_text">
471
472<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000473<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000474compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000475</ul>
476
477</div>
478
479<!-- ======================================================================= -->
480<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000481 <a name="arm-be">Known problems with the ARM back-end</a>
482</div>
483
484<div class="doc_text">
485
486<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000487<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000488processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000489results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000490<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
491</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000492<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
493 execute
Chris Lattner57a460e2007-05-23 04:39:32 +0000494programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000495</ul>
496
497</div>
498
499<!-- ======================================================================= -->
500<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000501 <a name="sparc-be">Known problems with the SPARC back-end</a>
502</div>
503
504<div class="doc_text">
505
506<ul>
507<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
508 support the 64-bit SPARC ABI (-m64).</li>
509</ul>
510
511</div>
512
513<!-- ======================================================================= -->
514<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000515 <a name="alpha-be">Known problems with the Alpha back-end</a>
516</div>
517
518<div class="doc_text">
519
520<ul>
521
522<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
523appropriate nops inserted to ensure restartability.</li>
524
John Criswellc0c186d2005-11-08 21:11:33 +0000525</ul>
526</div>
527
Chris Lattner26299222006-11-18 07:51:14 +0000528<!-- ======================================================================= -->
529<div class="doc_subsection">
530 <a name="ia64-be">Known problems with the IA64 back-end</a>
531</div>
532
533<div class="doc_text">
534
535<ul>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000536<li>The Itanium backend is highly experimental, and has a number of known
537 issues. We are looking for a maintainer for the Itanium backend. If you
538 are interested, please contact the llvmdev mailing list.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000539</ul>
540
541</div>
542
543<!-- ======================================================================= -->
544<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000545 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000546</div>
547
548<div class="doc_text">
549
550<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000551<li><a href="http://llvm.org/PR802">The C backend has only basic support for
552 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000553<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
554 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sands27aff872008-06-08 20:18:35 +0000555 C++ code compiled with llc or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000556<li>The C backend does not support all exception handling constructs.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000557</ul>
558
559</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000560
Misha Brukman500bc302003-11-22 00:38:41 +0000561
562<!-- ======================================================================= -->
563<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000564 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000565</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000566
Misha Brukman500bc302003-11-22 00:38:41 +0000567<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000568
Chris Lattner252b83d2008-02-06 18:00:06 +0000569<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
570Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000571llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000572
Chris Lattner5733b272008-06-05 06:35:40 +0000573<p>The only major language feature of GCC not supported by llvm-gcc is
574 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
575 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000576 supported on some targets (these are used when you take the address of a
577 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000578
Chris Lattner5733b272008-06-05 06:35:40 +0000579<p>If you run into GCC extensions which are not supported, please let us know.
580</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000581
Misha Brukman500bc302003-11-22 00:38:41 +0000582</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000583
Misha Brukman500bc302003-11-22 00:38:41 +0000584<!-- ======================================================================= -->
585<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000586 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000587</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000588
Misha Brukman500bc302003-11-22 00:38:41 +0000589<div class="doc_text">
590
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000591<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000592tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000593itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000594
Misha Brukman500bc302003-11-22 00:38:41 +0000595<ul>
Anton Korobeynikov0021fc12008-10-11 18:27:16 +0000596<li>Exception handling works well on the X86 and PowerPC targets. Currently
597 only linux and darwin targets are supported (both 32 and 64 bit).</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000598</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000599
Misha Brukman500bc302003-11-22 00:38:41 +0000600</div>
601
Misha Brukman500bc302003-11-22 00:38:41 +0000602
Chris Lattner2b659ef2008-02-12 06:29:45 +0000603<!-- ======================================================================= -->
604<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000605 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000606</div>
607
608<div class="doc_text">
609The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
610technology and problems should be expected.
611<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000612<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattner2b659ef2008-02-12 06:29:45 +0000613to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sands27aff872008-06-08 20:18:35 +0000614however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000615which does support trampolines.</li>
616<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
617Workaround: configure with --disable-bootstrap.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000618<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
619and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
620(c380004 also fails with gcc-4.2 mainline).</li>
621<li>Some gcc specific Ada tests continue to crash the compiler.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000622<li>The -E binder option (exception backtraces)
623<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
624crashing if an exception is raised. Workaround: do not use -E.</li>
625<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
626or finish at a non-byte offset</a> in a record. Workaround: do not pack records
627or use representation clauses that result in a field of a non-discrete type
628starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000629<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
630'main' as generated by the Ada binder to be invalid</a>.
631Workaround: hand edit the file to use pointers for <tt>argv</tt> and
632<tt>envp</tt> rather than integers.</li>
633<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
634ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000635</ul>
636</div>
637
Chris Lattner79c3fe12003-10-02 04:57:28 +0000638<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000639<div class="doc_section">
640 <a name="additionalinfo">Additional Information</a>
641</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000642<!-- *********************************************************************** -->
643
Misha Brukman500bc302003-11-22 00:38:41 +0000644<div class="doc_text">
645
Chris Lattner416db102005-05-16 17:13:10 +0000646<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000647href="http://llvm.org">LLVM web page</a>, in particular in the <a
648href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000649contains versions of the API documentation which is up-to-date with the
650Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000651You can access versions of these documents specific to this release by going
652into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000653
Misha Brukman500bc302003-11-22 00:38:41 +0000654<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000655us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000656lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000657
Misha Brukman500bc302003-11-22 00:38:41 +0000658</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000659
660<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000661
Misha Brukman500bc302003-11-22 00:38:41 +0000662<hr>
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Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000669 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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