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Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]7 <title>LLVM 2.4 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]11<div class="doc_title">LLVM 2.4 Release Notes</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]12
13<ol>
14 <li><a href="#intro">Introduction</a></li>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]15 <li><a href="#changes">Major Changes and Sub-project Status</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]16 <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 +0000[diff] [blame]36infrastructure, release 2.4. Here we describe the status of LLVM, including
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]37major 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
47<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]48main 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 +0000[diff] [blame]51
52</div>
53
54<!-- *********************************************************************** -->
55<div class="doc_section">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]56 <a name="changes">Major Changes and Sub-project Status</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]57</div>
58<!-- *********************************************************************** -->
59
60<div class="doc_text">
61
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]62<p>This is the fifteenth public release of the LLVM Compiler Infrastructure.
63It includes a large number of features and refinements from LLVM 2.3.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]64
65</div>
66
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]67<!-- Unfinished features in 2.4:
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]68 Machine LICM
69 Machine Sinking
70 LegalizeDAGTypes
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]71 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 +0000[diff] [blame]73 -->
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]74
75 <!-- for announcement email:
76 mention dev mtg
77 Xcode 3.1.1?
78 -->
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]79
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]80<!--=========================================================================-->
81<div class="doc_subsection">
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]82<a name="changes">Major Changes in LLVM 2.4</a>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]83</div>
84
85<div class="doc_text">
86
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]87<p>The LLVM IR generated by llvm-gcc now doesn't name instructions. Use the
88 instnamer pass if you want them.</p>
89
90
91
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]92
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]93<p>LLVM API Changes:</p>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]94
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]95<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]96<li>....</li>
Daniel Dunbardcb129a2008-10-11 21:26:56 +0000[diff] [blame]97
98<li>... Attributes changes ... </li>
99
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]100<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 +0000[diff] [blame]104
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]105<li>API change: BinaryOperator::create -> Create (CmpInst, CastInst too)</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]106<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>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]108</ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]109</div>
110
111<!--=========================================================================-->
112<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]113<a name="otherprojects">Other LLVM Sub-Projects</a>
114</div>
115
116<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]117<p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]118The core LLVM 2.4 distribution currently consists of code from the core LLVM
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]119repository (which roughly contains the LLVM optimizer, code generators and
120supporting tools) and the llvm-gcc repository. In addition to this code, the
121LLVM Project includes other sub-projects that are in development. The two which
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]122are the most actively developed are the <a href="#clang">Clang Project</a> and
123<a href="#vmkit">vmkit Project</a>.
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]124</p>
125</div>
126
127<!--=========================================================================-->
128<div class="doc_subsubsection">
129<a name="vmkit">vmkit</a>
130</div>
131
132<div class="doc_text">
133<p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]134The <a href="http://vmkit.llvm.org/">"vmkit" project</a> is an implementation of
135a JVM and a CLI Virtual Machines (Microsoft .NET is an
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]136implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
137
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]138<p>...</p>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]139
140</div>
141
142<!--=========================================================================-->
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]143<div class="doc_subsubsection">
144<a name="clang">Clang</a>
145</div>
146
147<div class="doc_text">
148
149<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
150a set of new 'LLVM native' front-end technologies for the LLVM optimizer
151and code generator. Clang is continuing to make major strides forward in all
152areas. Its C and Objective-C parsing support is very solid, and the code
153generation support is far enough along to build many C applications. While not
154yet production quality, it is progressing very nicely. In addition, C++
155front-end work has started to make significant progress.</p>
156
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]157<p>Codegen progress/state
158</p>
159
160<p>
161<a href="http://clang.llvm.org/StaticAnalysis.html">static analysis tool</a>
162</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]163
164</div>
165
166
167<!-- *********************************************************************** -->
168<div class="doc_section">
169 <a name="whatsnew">What's New?</a>
170</div>
171<!-- *********************************************************************** -->
172
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]173<div class="doc_text">
174
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]175<p>LLVM 2.4 includes a huge number of bug fixes, performance tweaks and minor
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]176improvements. Some of the major improvements and new features are listed in
177this section.
178</p>
179</div>
180
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]181<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]182<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]183<a name="majorfeatures">Major New Features</a>
184</div>
185
186<div class="doc_text">
187
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]188<p>LLVM 2.4 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]189
190<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]191<li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]192 <p>MRVs got generalized to FCAs. getresult is gone, ret with multiple values
193 is gone.</p>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]194 </li>
195
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]196<li><p>-O0 compile times overall much faster</p></li>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]197
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]198<li><p>Attrs changes?</p></li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]199
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]200
201<li><p>Initial PIC16 port</p></li>
202
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]203<li><p> Support the rest of the atomic __sync builtins</p></li>
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]204
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]205<li><p>...</p></li>
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]206
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]207</ul>
208
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]209</div>
210
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]211
212<!--=========================================================================-->
213<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]214<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]215</div>
216
217<div class="doc_text">
218
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]219<p>LLVM 2.4 fully supports the llvm-gcc 4.2 front-end, and includes support
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]220for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]221
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]222<p>
223<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]224<li>...</li>
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]225
Gabor Greif0e49cc82008-06-09 06:06:18 +0000[diff] [blame]226</ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]227
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]228</div>
229
230
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]231<!--=========================================================================-->
232<div class="doc_subsection">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]233<a name="coreimprovements">LLVM Core Improvements</a>
234</div>
235
236<div class="doc_text">
237<p>New features include:
238</p>
239
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]240<ul>
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]241<li>use diet patch landed: saved 15% IR memory footprint</li>
242<li>LLVM IR now directly represents "common" linkage, instead of
243 representing it as a form of weak linkage.</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]244<li>DebugInfoBuilder</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]245<li>...</li>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]246</ul>
247
248</div>
249
250<!--=========================================================================-->
251<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]252<a name="optimizer">Optimizer Improvements</a>
253</div>
254
255<div class="doc_text">
256
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]257<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]258LLVM 2.4 optimizers support a few major enhancements:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]259
260<ul>
261
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]262<li>GVN now does local PRE?</li>
263
264<li>Matthijs' Dead argument elimination rewrite</li>
265
Chris Lattnera5a49382008-10-12 18:30:33 +0000[diff] [blame]266<li>Old-ADCE used control dependence and deleted output-free infinite loops.
267Added a new Loop deletion pass (for deleting output free provably-finite loops)
268and rewrote ADCE to be simpler faster, and not need control dependence.</li>
269
270<li>SparsePropagation framework for lattice-based dataflow solvers.</li>
271
272<li>LoadVN and GCSE finally bit the dust?</li>
273
274<li>Tail duplication was is removed from the standard optimizer sequence.</li>
275
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]276<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
277pulled out of instcombine and put into a new ValueTracking.h file, where they
278can be reused by other passes.</li>
279
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]280</ul>
281
282</div>
283
284<!--=========================================================================-->
285<div class="doc_subsection">
286<a name="codegen">Code Generator Improvements</a>
287</div>
288
289<div class="doc_text">
290
291<p>We put a significant amount of work into the code generator infrastructure,
292which allows us to implement more aggressive algorithms and make it run
293faster:</p>
294
295<ul>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]296<li>2-addr pass can now remat trivial insts to avoid a copy.</li>
297<li>spiller to commute instructions in order to fold a reload</li>
298<li>Stack slot coloring?</li>
299<li>Live intervals renumbering? Is this useful to external people?</li>
300<li>'is as cheap as a move' instruction flag</li>
301<li>Improvements to selection dag viewing</li>
302<li>fast isel</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]303<li>Selection dag speedups</li>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]304<li>asmwriter + raw_ostream -> fastah</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]305<li>...</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]306
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]307</ul>
308
309</div>
310
311
312<!--=========================================================================-->
313<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]314<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]315</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]316
317<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]318<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319</p>
320
321<ul>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]322<li>Exception handling is supported by default on Linux/x86-64.</li>
323<li>Position Independent Code (PIC) is now support on Linux/x86-64.</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]324<li>...</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]325
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]326</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]327
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]328</div>
329
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]330<!--=========================================================================-->
331<div class="doc_subsection">
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]332<a name="targetspecific">Other Target Specific Improvements</a>
333</div>
334
335<div class="doc_text">
336<p>New target-specific features include:
337</p>
338
339<ul>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]340<li>....</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]341</ul>
342
343</div>
344
345
346
347<!--=========================================================================-->
348<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]349<a name="otherimprovements">Other Improvements</a>
350</div>
351
352<div class="doc_text">
353<p>New features include:
354</p>
355
356<ul>
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame^]357<li>raw_ostream + formatting</li>
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]358<li>...</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]359</ul>
360
361</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]362
363<!-- *********************************************************************** -->
364<div class="doc_section">
365 <a name="portability">Portability and Supported Platforms</a>
366</div>
367<!-- *********************************************************************** -->
368
369<div class="doc_text">
370
371<p>LLVM is known to work on the following platforms:</p>
372
373<ul>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]374<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]375 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]376<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 +0000[diff] [blame]377 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]378<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]379<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
380 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]381<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]382<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]383<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]384</ul>
385
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]386<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]387to the machine and operating system on which it is built. However, minor
388porting may be required to get LLVM to work on new platforms. We welcome your
389portability patches and reports of successful builds or error messages.</p>
390
391</div>
392
393<!-- *********************************************************************** -->
394<div class="doc_section">
395 <a name="knownproblems">Known Problems</a>
396</div>
397<!-- *********************************************************************** -->
398
399<div class="doc_text">
400
401<p>This section contains all known problems with the LLVM system, listed by
402component. As new problems are discovered, they will be added to these
403sections. If you run into a problem, please check the <a
404href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
405there isn't already one.</p>
406
407</div>
408
409<!-- ======================================================================= -->
410<div class="doc_subsection">
411 <a name="experimental">Experimental features included with this release</a>
412</div>
413
414<div class="doc_text">
415
416<p>The following components of this LLVM release are either untested, known to
417be broken or unreliable, or are in early development. These components should
418not be relied on, and bugs should not be filed against them, but they may be
419useful to some people. In particular, if you would like to work on one of these
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]420components, please contact us on the <a
421href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]422
423<ul>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]424<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]425<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]426 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]427</ul>
428
429</div>
430
431<!-- ======================================================================= -->
432<div class="doc_subsection">
433 <a name="x86-be">Known problems with the X86 back-end</a>
434</div>
435
436<div class="doc_text">
437
438<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]439 <li>The X86 backend does not yet support
440 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
441 floating point stack</a>. It supports the 'f' and 't' constraints, but not
442 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]443 <li>The X86 backend generates inefficient floating point code when configured
444 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]445 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]446 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
447 currently due
448 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]449 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
450 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]451 <li>The X86-64 backend does not yet support the LLVM IR instruction
452 <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
453 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]454</ul>
455
456</div>
457
458<!-- ======================================================================= -->
459<div class="doc_subsection">
460 <a name="ppc-be">Known problems with the PowerPC back-end</a>
461</div>
462
463<div class="doc_text">
464
465<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]466<li>The Linux PPC32/ABI support needs testing for the interpreter and static
467compilation, and lacks support for debug information.</li>
468</ul>
469
470</div>
471
472<!-- ======================================================================= -->
473<div class="doc_subsection">
474 <a name="arm-be">Known problems with the ARM back-end</a>
475</div>
476
477<div class="doc_text">
478
479<ul>
480<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]481processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]482results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
483<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
484</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]485<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
486 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]487programs compiled with LLVM. Please use more recent versions of QEMU.</li>
488</ul>
489
490</div>
491
492<!-- ======================================================================= -->
493<div class="doc_subsection">
494 <a name="sparc-be">Known problems with the SPARC back-end</a>
495</div>
496
497<div class="doc_text">
498
499<ul>
500<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
501 support the 64-bit SPARC ABI (-m64).</li>
502</ul>
503
504</div>
505
506<!-- ======================================================================= -->
507<div class="doc_subsection">
508 <a name="alpha-be">Known problems with the Alpha back-end</a>
509</div>
510
511<div class="doc_text">
512
513<ul>
514
515<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
516appropriate nops inserted to ensure restartability.</li>
517
518</ul>
519</div>
520
521<!-- ======================================================================= -->
522<div class="doc_subsection">
523 <a name="ia64-be">Known problems with the IA64 back-end</a>
524</div>
525
526<div class="doc_text">
527
528<ul>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]529<li>The Itanium backend is highly experimental, and has a number of known
530 issues. We are looking for a maintainer for the Itanium backend. If you
531 are interested, please contact the llvmdev mailing list.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]532</ul>
533
534</div>
535
536<!-- ======================================================================= -->
537<div class="doc_subsection">
538 <a name="c-be">Known problems with the C back-end</a>
539</div>
540
541<div class="doc_text">
542
543<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]544<li><a href="http://llvm.org/PR802">The C backend has only basic support for
545 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]546<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
547 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]548 C++ code compiled with llc or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]549<li>The C backend does not support all exception handling constructs.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]550</ul>
551
552</div>
553
554
555<!-- ======================================================================= -->
556<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]557 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]558</div>
559
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]560<div class="doc_text">
561
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]562<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
563Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]564llvmdev mailing list if you are interested.</p>
565
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]566<p>The only major language feature of GCC not supported by llvm-gcc is
567 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
568 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]569 supported on some targets (these are used when you take the address of a
570 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]571
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]572<p>If you run into GCC extensions which are not supported, please let us know.
573</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]574
575</div>
576
577<!-- ======================================================================= -->
578<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]579 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]580</div>
581
582<div class="doc_text">
583
584<p>The C++ front-end is considered to be fully
585tested and works for a number of non-trivial programs, including LLVM
586itself, Qt, Mozilla, etc.</p>
587
588<ul>
Anton Korobeynikovd9a17932008-10-11 18:27:16 +0000[diff] [blame]589<li>Exception handling works well on the X86 and PowerPC targets. Currently
590 only linux and darwin targets are supported (both 32 and 64 bit).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]591</ul>
592
593</div>
594
595
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]596<!-- ======================================================================= -->
597<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]598 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]599</div>
600
601<div class="doc_text">
602The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
603technology and problems should be expected.
604<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]605<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]606to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]607however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]608which does support trampolines.</li>
609<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
610Workaround: configure with --disable-bootstrap.</li>
611<li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]612fail (c380004 also fails with gcc-4.2 mainline). When built at -O3, the
613<a href="http://llvm.org/PR2421">cxg2021</a> ACATS test also fails.</li>
614<li>Some gcc specific Ada tests continue to crash the compiler. The testsuite
615reports most tests as having failed even though they pass.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]616<li>The -E binder option (exception backtraces)
617<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
618crashing if an exception is raised. Workaround: do not use -E.</li>
619<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
620or finish at a non-byte offset</a> in a record. Workaround: do not pack records
621or use representation clauses that result in a field of a non-discrete type
622starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]623<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
624'main' as generated by the Ada binder to be invalid</a>.
625Workaround: hand edit the file to use pointers for <tt>argv</tt> and
626<tt>envp</tt> rather than integers.</li>
627<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
628ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]629</ul>
630</div>
631
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]632<!-- *********************************************************************** -->
633<div class="doc_section">
634 <a name="additionalinfo">Additional Information</a>
635</div>
636<!-- *********************************************************************** -->
637
638<div class="doc_text">
639
640<p>A wide variety of additional information is available on the <a
641href="http://llvm.org">LLVM web page</a>, in particular in the <a
642href="http://llvm.org/docs/">documentation</a> section. The web page also
643contains versions of the API documentation which is up-to-date with the
644Subversion version of the source code.
645You can access versions of these documents specific to this release by going
646into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
647
648<p>If you have any questions or comments about LLVM, please feel free to contact
649us via the <a href="http://llvm.org/docs/#maillist"> mailing
650lists</a>.</p>
651
652</div>
653
654<!-- *********************************************************************** -->
655
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