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Chris Lattner857fb132008-10-11 18:18:28 +00007 <title>LLVM 2.4 Release Notes</title>
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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
Chris Lattnerfb97b2d2008-10-13 18:11:54 +000076repository (which roughly includes 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
Duncan Sandsbf8c4f22008-10-13 18:33:28 +000080the <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 Lattnerfb97b2d2008-10-13 18:11:54 +000088<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattner8348b472008-06-08 21:58:17 +000089</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
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000104</div>
105
106<!--=========================================================================-->
107<div class="doc_subsection">
108<a name="clangsa">Clang Static Analyzer</a>
109</div>
110
111<div class="doc_text">
112
113<p>The
Chris Lattner857fb132008-10-11 18:18:28 +0000114<a href="http://clang.llvm.org/StaticAnalysis.html">static analysis tool</a>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000115.</p>
Chris Lattner8348b472008-06-08 21:58:17 +0000116
117</div>
118
Chris Lattner96a445e2008-10-13 18:01:01 +0000119<!--=========================================================================-->
120<div class="doc_subsection">
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000121<a name="vmkit">vmkit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner96a445e2008-10-13 18:01:01 +0000122</div>
123
124<div class="doc_text">
125<p>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000126The <a href="http://vmkit.llvm.org/">vmkit project</a> is an implementation of
Chris Lattner96a445e2008-10-13 18:01:01 +0000127a JVM and a CLI Virtual Machines (Microsoft .NET is an
128implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
129
130<p>...</p>
131
132</div>
133
Chris Lattner8348b472008-06-08 21:58:17 +0000134
135<!-- *********************************************************************** -->
136<div class="doc_section">
Chris Lattner96a445e2008-10-13 18:01:01 +0000137 <a name="whatsnew">What's New in LLVM?</a>
Chris Lattner8348b472008-06-08 21:58:17 +0000138</div>
139<!-- *********************************************************************** -->
140
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000141<div class="doc_text">
142
Chris Lattnerf6662f92008-10-13 17:57:36 +0000143<p>This release includes a huge number of bug fixes, performance tweaks and
144minor improvements. Some of the major improvements and new features are listed
145in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000146</p>
147</div>
148
Chris Lattner8348b472008-06-08 21:58:17 +0000149<!--=========================================================================-->
Chris Lattnerea34f642008-06-08 21:34:41 +0000150<div class="doc_subsection">
Chris Lattner252b83d2008-02-06 18:00:06 +0000151<a name="majorfeatures">Major New Features</a>
152</div>
153
154<div class="doc_text">
155
Chris Lattner857fb132008-10-11 18:18:28 +0000156<p>LLVM 2.4 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000157
158<ul>
Chris Lattnerb82eb062008-10-13 20:47:20 +0000159<li><p>The most visible end-user change in LLVM 2.4 is that it includes many
160optimizations and changes ot make -O0 compile times much faster. You should see
161improvements on the order of 30% or more faster than LLVM 2.3. There are many
162pieces to this change, described in more detail below. The speedups and new
163components can also be used for JIT compilers that want fast compilation as
164well.</p></li>
Chris Lattner857fb132008-10-11 18:18:28 +0000165
Chris Lattnerb82eb062008-10-13 20:47:20 +0000166<li><p>The biggest change to the LLVM IR is that Multiple Return Values (which
167were introduced in LLVM 2.3) have been generalized to full support for "First
168Class Aggregate" values in LLVM 2.4. This means that LLVM IR supports using
169structs and arrays as values in a function. This capability is mostly useful
170for front-end authors, who prefer to treat things like complex numbers, simple
171tuples, dope vectors, etc as Value*'s instead of as a tuple of Value*'s or as
172memory values.</p></li>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000173
Chris Lattnerb82eb062008-10-13 20:47:20 +0000174<li><p>LLVM 2.4 also includes an initial port for the PIC16 microprocessor. This
175is the LLVM targer that only has support for 8 bit registers, and a number of
176other crazy constraints. While the port is still in early development stages,
177it shows some interesting things you can do with LLVM.</p></li>
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000178
Chris Lattner8170c102008-02-10 08:18:42 +0000179</ul>
180
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000181</div>
182
Chris Lattner791f77b2008-06-05 06:25:56 +0000183
184<!--=========================================================================-->
185<div class="doc_subsection">
Chris Lattnerea34f642008-06-08 21:34:41 +0000186<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattner791f77b2008-06-05 06:25:56 +0000187</div>
188
189<div class="doc_text">
190
Chris Lattnerb82eb062008-10-13 20:47:20 +0000191<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
192front-ends and driver with the LLVM optimizer and code generator. It currently
193includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattner791f77b2008-06-05 06:25:56 +0000194
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000195<ul>
Chris Lattnerb82eb062008-10-13 20:47:20 +0000196<li>LLVM 2.4 supports the full set of atomic __sync builtins. LLVM 2.3 only
197supported those used by OpenMP, but 2.4 supports them all. Not all targets
198support all builtins, but X86 and PowerPC do.</li>
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000199
Chris Lattnerb82eb062008-10-13 20:47:20 +0000200<li>llvm-gcc now supports an -flimited-precision option, which tells the
201compiler that it is ok to use low-precision approximations of certain libm
202functions (like tan, log, etc). This allows you to get high performance if you
203only need (say) 14-bits of precision.</li>
204
205<li>llvm-gcc now supports a C language extension known as "<a
206href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks
207</a>. This feature is similar to nested functions and closures, but does not
208require stack trampolines (with most ABIs) and supports returning closures
209from functions that define them. Note that actually <em>using</em> Blocks
210requires a small runtime that is not included with llvm-gcc.</li>
211
212<li>llvm-gcc now supports a new <tt>-flto</tt> option. On systems that support
213transparent Link Time Optimization (currently Darwin systems with Xcode 3.1 and
214later) this allows the use of LTO with other optimization levels like -Os.
215Previously, LTO could only be used with -O4, which implied optimizations in
216-O3 that can increase code size.</li>
Gabor Greifa3bd11d2008-06-09 06:06:18 +0000217</ul>
Chris Lattner791f77b2008-06-05 06:25:56 +0000218
Chris Lattner791f77b2008-06-05 06:25:56 +0000219</div>
220
221
Chris Lattner84977642007-09-21 03:54:09 +0000222<!--=========================================================================-->
223<div class="doc_subsection">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000224<a name="coreimprovements">LLVM Core Improvements</a>
225</div>
226
227<div class="doc_text">
228<p>New features include:
229</p>
230
Chris Lattner791f77b2008-06-05 06:25:56 +0000231<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000232<li>vector shifts in the IR: no codegen support yet</li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000233<li>use diet patch landed: saved 15% IR memory footprint</li>
234<li>LLVM IR now directly represents "common" linkage, instead of
235 representing it as a form of weak linkage.</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000236<li>DebugInfoBuilder</li>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000237<li>.ll printing format change: %3 = add i32 4, 2</li>
Duncan Sandsbf8c4f22008-10-13 18:33:28 +0000238<li>opt-size, noinline, alwaysinline function attributes</li>
Chris Lattnerb82eb062008-10-13 20:47:20 +0000239<li>Attrs: function, return, param.</p></li>
Chris Lattner857fb132008-10-11 18:18:28 +0000240<li>...</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000241</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000242
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000243</div>
244
245<!--=========================================================================-->
246<div class="doc_subsection">
Chris Lattneracce85d2008-02-10 07:46:44 +0000247<a name="optimizer">Optimizer Improvements</a>
248</div>
249
250<div class="doc_text">
251
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000252<p>In addition to a huge array of bug fixes and minor performance tweaks, the
Chris Lattner857fb132008-10-11 18:18:28 +0000253LLVM 2.4 optimizers support a few major enhancements:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000254
255<ul>
256
Chris Lattner547a3912008-10-12 19:47:48 +0000257<li>GVN now does local PRE?</li>
258
259<li>Matthijs' Dead argument elimination rewrite</li>
260
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000261<li>Old-ADCE used control dependence and deleted output-free infinite loops.
262Added a new Loop deletion pass (for deleting output free provably-finite loops)
263and rewrote ADCE to be simpler faster, and not need control dependence.</li>
264
265<li>SparsePropagation framework for lattice-based dataflow solvers.</li>
266
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000267<li>Tail duplication was removed from the standard optimizer sequence.</li>
Chris Lattnercce6d4b2008-10-12 18:30:33 +0000268
Chris Lattner547a3912008-10-12 19:47:48 +0000269<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
270pulled out of instcombine and put into a new ValueTracking.h file, where they
271can be reused by other passes.</li>
272
Duncan Sands1050d732008-10-13 18:42:43 +0000273<li>The new AddReadAttrs pass works out which functions are read-only or
274read-none (these correspond to 'pure' and 'const' in C) and marks them
275with the appropriate attribute.</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000276</ul>
277
278</div>
279
280<!--=========================================================================-->
281<div class="doc_subsection">
282<a name="codegen">Code Generator Improvements</a>
283</div>
284
285<div class="doc_text">
286
287<p>We put a significant amount of work into the code generator infrastructure,
288which allows us to implement more aggressive algorithms and make it run
289faster:</p>
290
291<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000292<li>asm writers split out to their own library to avoid JITs having to link
293 them in.</li>
294<li>Big asm writer refactoring + TargetAsmInfo</li>
295<li>2-addr pass and coalescer can now remat trivial insts to avoid a copy.</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000296<li>spiller to commute instructions in order to fold a reload</li>
297<li>Stack slot coloring?</li>
298<li>Live intervals renumbering? Is this useful to external people?</li>
299<li>'is as cheap as a move' instruction flag</li>
300<li>Improvements to selection dag viewing</li>
301<li>fast isel</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000302<li>Selection dag speedups</li>
Chris Lattner547a3912008-10-12 19:47:48 +0000303<li>asmwriter + raw_ostream -> fastah</li>
Chris Lattner59b5ce42008-10-13 17:12:51 +0000304<li>Partitioned Boolean Quadratic Programming (PBQP) based register
305allocator.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000306<li>...</li>
Chris Lattner0b832202008-06-08 02:45:07 +0000307
Chris Lattner84977642007-09-21 03:54:09 +0000308</ul>
309
310</div>
311
312
313<!--=========================================================================-->
314<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000315<a name="x86specific">X86/X86-64 Specific Improvements</a>
Chris Lattner84977642007-09-21 03:54:09 +0000316</div>
Chris Lattner60893e52007-05-18 06:33:02 +0000317
Chris Lattner738bd302006-04-18 06:32:08 +0000318<div class="doc_text">
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000319<p>New target-specific features include:
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000320</p>
Chris Lattner26299222006-11-18 07:51:14 +0000321
322<ul>
Chris Lattner547a3912008-10-12 19:47:48 +0000323<li>Exception handling is supported by default on Linux/x86-64.</li>
Duncan Sandsbbf379a2008-10-13 17:32:15 +0000324<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000325<li>...</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000326
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000327</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000328
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000329</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000330
Chris Lattner84977642007-09-21 03:54:09 +0000331<!--=========================================================================-->
332<div class="doc_subsection">
Chris Lattner77d29b12008-06-05 08:02:49 +0000333<a name="targetspecific">Other Target Specific Improvements</a>
334</div>
335
336<div class="doc_text">
337<p>New target-specific features include:
338</p>
339
340<ul>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000341<li>MIPS floating point support?</li>
Duncan Sandsbbf379a2008-10-13 17:32:15 +0000342<li>PowerPC now supports trampolines.</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000343<li>....</li>
Chris Lattner77d29b12008-06-05 08:02:49 +0000344</ul>
Chris Lattner77d29b12008-06-05 08:02:49 +0000345
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000346</div>
Chris Lattner77d29b12008-06-05 08:02:49 +0000347
348
349<!--=========================================================================-->
350<div class="doc_subsection">
Chris Lattner84977642007-09-21 03:54:09 +0000351<a name="otherimprovements">Other Improvements</a>
352</div>
353
354<div class="doc_text">
355<p>New features include:
356</p>
357
358<ul>
Mikhail Glushenkov49feb452008-10-13 02:46:01 +0000359<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000360 support. It is now easier to experiment with <tt>llvmc2</tt> and
361 build your own tools based on it. </li>
Chris Lattner547a3912008-10-12 19:47:48 +0000362<li>raw_ostream + formatting</li>
Chris Lattnercdb0e4c2008-10-12 22:57:58 +0000363<li>Recycler + pool allocation stuff?</li>
Chris Lattner857fb132008-10-11 18:18:28 +0000364<li>...</li>
Chris Lattner84977642007-09-21 03:54:09 +0000365</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000366
Chris Lattner84977642007-09-21 03:54:09 +0000367</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000368
Chris Lattnerf6662f92008-10-13 17:57:36 +0000369<!--=========================================================================-->
370<div class="doc_subsection">
371<a name="changes">Major Changes and Removed Features</a>
372</div>
373
374<div class="doc_text">
375
Chris Lattner96a445e2008-10-13 18:01:01 +0000376<p>If you're already an LLVM user, this section lists some "gotchas" that you
377may run into upgrading from the previous release.</p>
378
Duncan Sandsbf8c4f22008-10-13 18:33:28 +0000379<p>The LLVM IR generated by llvm-gcc no longer names all instructions.
380 Use the instnamer pass if you want everything named.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000381
Duncan Sandsbf8c4f22008-10-13 18:33:28 +0000382<li>The LoadVN and GCSE passes have been removed.</li>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000383
384
385<p>LLVM API Changes:</p>
386
387<ul>
388
389<li>... Attributes changes ... </li>
390
391<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
392<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
393converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
394"llvm/Analysis/ValueTracking.h".</li>
395
396<li>API change: BinaryOperator::create -> Create (CmpInst, CastInst too)</li>
397<li>Various header files like "llvm/ADT/iterator" were given a .h suffix.
398 Change your code to #include "llvm/ADT/iterator.h" instead.</li>
399
400</ul>
401
402</div>
403
404
405
Chris Lattner19092612003-10-02 16:38:05 +0000406<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000407<div class="doc_section">
408 <a name="portability">Portability and Supported Platforms</a>
409</div>
Chris Lattner19092612003-10-02 16:38:05 +0000410<!-- *********************************************************************** -->
411
Misha Brukman500bc302003-11-22 00:38:41 +0000412<div class="doc_text">
413
John Criswell0b5b5e92004-12-08 20:35:47 +0000414<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000415
416<ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000417<li>Intel and AMD machines (IA32) running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000418 (and probably other unix-like systems).</li>
Chris Lattner000c73b2008-02-06 06:30:34 +0000419<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 +0000420 64-bit modes.</li>
Chris Lattner252b83d2008-02-06 18:00:06 +0000421<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000422<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
423 support is available for native builds with Visual C++).</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000424<li>Sun UltraSPARC workstations running Solaris 10.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000425<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif96a89c72008-06-05 18:39:01 +0000426<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000427</ul>
428
Chris Lattnerbc5786b2008-06-05 06:57:39 +0000429<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000430to the machine and operating system on which it is built. However, minor
431porting may be required to get LLVM to work on new platforms. We welcome your
432portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000433
Misha Brukman500bc302003-11-22 00:38:41 +0000434</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000435
436<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000437<div class="doc_section">
438 <a name="knownproblems">Known Problems</a>
439</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000440<!-- *********************************************************************** -->
441
Misha Brukman500bc302003-11-22 00:38:41 +0000442<div class="doc_text">
443
444<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000445component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000446sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000447href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000448there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000449
Misha Brukman500bc302003-11-22 00:38:41 +0000450</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000451
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000452<!-- ======================================================================= -->
453<div class="doc_subsection">
454 <a name="experimental">Experimental features included with this release</a>
455</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000456
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000457<div class="doc_text">
458
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000459<p>The following components of this LLVM release are either untested, known to
460be broken or unreliable, or are in early development. These components should
461not be relied on, and bugs should not be filed against them, but they may be
462useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000463components, please contact us on the <a
464href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000465
466<ul>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000467<li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
Duncan Sands27aff872008-06-08 20:18:35 +0000468<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattner000c73b2008-02-06 06:30:34 +0000469 value for this option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000470</ul>
471
472</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000473
Misha Brukman500bc302003-11-22 00:38:41 +0000474<!-- ======================================================================= -->
475<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000476 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000477</div>
478
479<div class="doc_text">
480
481<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000482 <li>The X86 backend does not yet support
483 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
484 floating point stack</a>. It supports the 'f' and 't' constraints, but not
485 'u'.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000486 <li>The X86 backend generates inefficient floating point code when configured
487 to generate code for systems that don't have SSE2.</li>
Duncan Sands47eff2b2008-06-08 19:38:43 +0000488 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000489 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
490 currently due
491 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000492 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
493 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000494 <li>The X86-64 backend does not yet support the LLVM IR instruction
495 <tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
496 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000497</ul>
498
499</div>
500
501<!-- ======================================================================= -->
502<div class="doc_subsection">
503 <a name="ppc-be">Known problems with the PowerPC back-end</a>
504</div>
505
506<div class="doc_text">
507
508<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000509<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000510compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000511</ul>
512
513</div>
514
515<!-- ======================================================================= -->
516<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000517 <a name="arm-be">Known problems with the ARM back-end</a>
518</div>
519
520<div class="doc_text">
521
522<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000523<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000524processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000525results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000526<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
527</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000528<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
529 execute
Chris Lattner57a460e2007-05-23 04:39:32 +0000530programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000531</ul>
532
533</div>
534
535<!-- ======================================================================= -->
536<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000537 <a name="sparc-be">Known problems with the SPARC back-end</a>
538</div>
539
540<div class="doc_text">
541
542<ul>
543<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
544 support the 64-bit SPARC ABI (-m64).</li>
545</ul>
546
547</div>
548
549<!-- ======================================================================= -->
550<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000551 <a name="alpha-be">Known problems with the Alpha back-end</a>
552</div>
553
554<div class="doc_text">
555
556<ul>
557
558<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
559appropriate nops inserted to ensure restartability.</li>
560
John Criswellc0c186d2005-11-08 21:11:33 +0000561</ul>
562</div>
563
Chris Lattner26299222006-11-18 07:51:14 +0000564<!-- ======================================================================= -->
565<div class="doc_subsection">
566 <a name="ia64-be">Known problems with the IA64 back-end</a>
567</div>
568
569<div class="doc_text">
570
571<ul>
Chris Lattner04af7cb2008-06-08 23:12:47 +0000572<li>The Itanium backend is highly experimental, and has a number of known
573 issues. We are looking for a maintainer for the Itanium backend. If you
574 are interested, please contact the llvmdev mailing list.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000575</ul>
576
577</div>
578
579<!-- ======================================================================= -->
580<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000581 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000582</div>
583
584<div class="doc_text">
585
586<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000587<li><a href="http://llvm.org/PR802">The C backend has only basic support for
588 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000589<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
590 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sands27aff872008-06-08 20:18:35 +0000591 C++ code compiled with llc or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000592<li>The C backend does not support all exception handling constructs.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000593</ul>
594
595</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000596
Misha Brukman500bc302003-11-22 00:38:41 +0000597
598<!-- ======================================================================= -->
599<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000600 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000601</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000602
Misha Brukman500bc302003-11-22 00:38:41 +0000603<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000604
Chris Lattner252b83d2008-02-06 18:00:06 +0000605<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
606Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000607llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000608
Chris Lattner5733b272008-06-05 06:35:40 +0000609<p>The only major language feature of GCC not supported by llvm-gcc is
610 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
611 are only supported on some targets. For example, trampolines are only
Duncan Sands27aff872008-06-08 20:18:35 +0000612 supported on some targets (these are used when you take the address of a
613 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000614
Chris Lattner5733b272008-06-05 06:35:40 +0000615<p>If you run into GCC extensions which are not supported, please let us know.
616</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000617
Misha Brukman500bc302003-11-22 00:38:41 +0000618</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000619
Misha Brukman500bc302003-11-22 00:38:41 +0000620<!-- ======================================================================= -->
621<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000622 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000623</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000624
Misha Brukman500bc302003-11-22 00:38:41 +0000625<div class="doc_text">
626
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000627<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000628tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000629itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000630
Misha Brukman500bc302003-11-22 00:38:41 +0000631<ul>
Anton Korobeynikov0021fc12008-10-11 18:27:16 +0000632<li>Exception handling works well on the X86 and PowerPC targets. Currently
633 only linux and darwin targets are supported (both 32 and 64 bit).</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000634</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000635
Misha Brukman500bc302003-11-22 00:38:41 +0000636</div>
637
Misha Brukman500bc302003-11-22 00:38:41 +0000638
Chris Lattner2b659ef2008-02-12 06:29:45 +0000639<!-- ======================================================================= -->
640<div class="doc_subsection">
Chris Lattner5733b272008-06-05 06:35:40 +0000641 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000642</div>
643
644<div class="doc_text">
645The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
646technology and problems should be expected.
647<ul>
Duncan Sands27aff872008-06-08 20:18:35 +0000648<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattner2b659ef2008-02-12 06:29:45 +0000649to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sands27aff872008-06-08 20:18:35 +0000650however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000651which does support trampolines.</li>
652<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
653Workaround: configure with --disable-bootstrap.</li>
Duncan Sands978bcee2008-10-13 17:27:23 +0000654<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
655and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
656(c380004 also fails with gcc-4.2 mainline).</li>
657<li>Some gcc specific Ada tests continue to crash the compiler.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000658<li>The -E binder option (exception backtraces)
659<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
660crashing if an exception is raised. Workaround: do not use -E.</li>
661<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
662or finish at a non-byte offset</a> in a record. Workaround: do not pack records
663or use representation clauses that result in a field of a non-discrete type
664starting or finishing in the middle of a byte.</li>
Chris Lattnere6e1b352008-06-08 21:19:07 +0000665<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
666'main' as generated by the Ada binder to be invalid</a>.
667Workaround: hand edit the file to use pointers for <tt>argv</tt> and
668<tt>envp</tt> rather than integers.</li>
669<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
670ignored</a>.</li>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000671</ul>
672</div>
673
Chris Lattner79c3fe12003-10-02 04:57:28 +0000674<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000675<div class="doc_section">
676 <a name="additionalinfo">Additional Information</a>
677</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000678<!-- *********************************************************************** -->
679
Misha Brukman500bc302003-11-22 00:38:41 +0000680<div class="doc_text">
681
Chris Lattner416db102005-05-16 17:13:10 +0000682<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000683href="http://llvm.org">LLVM web page</a>, in particular in the <a
684href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000685contains versions of the API documentation which is up-to-date with the
686Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000687You can access versions of these documents specific to this release by going
688into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000689
Misha Brukman500bc302003-11-22 00:38:41 +0000690<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000691us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000692lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000693
Misha Brukman500bc302003-11-22 00:38:41 +0000694</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000695
696<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000697
Misha Brukman500bc302003-11-22 00:38:41 +0000698<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000699<address>
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Misha Brukman2061e892003-11-22 01:23:39 +0000704
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000705 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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