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Jeffrey Yasskin0830b972010-01-28 01:14:43 +00007 <title>LLVM 2.7 Release Notes</title>
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9<body>
Chris Lattner3d482502003-10-02 04:57:28 +000010
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000011<div class="doc_title">LLVM 2.7 Release Notes</div>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +000012
Chris Lattnerc871bac2010-03-17 04:02:39 +000013<img align=right src="http://llvm.org/img/DragonSmall.png"
14 width="136" height="136">
15
Chris Lattner3d482502003-10-02 04:57:28 +000016<ol>
Misha Brukman80731b92003-11-22 00:38:41 +000017 <li><a href="#intro">Introduction</a></li>
Chris Lattnerf5cd9862008-10-13 18:01:01 +000018 <li><a href="#subproj">Sub-project Status Update</a></li>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000019 <li><a href="#externalproj">External Projects Using LLVM 2.7</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 2.7?</a></li>
Chris Lattner77a51732004-04-30 22:17:12 +000021 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +000022 <li><a href="#portability">Portability and Supported Platforms</a></li>
Dan Gohmanad888912008-10-14 16:23:02 +000023 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +000024 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +000025</ol>
26
Chris Lattner020e1fc2004-05-23 21:07:27 +000027<div class="doc_author">
Dan Gohmanad888912008-10-14 16:23:02 +000028 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman80731b92003-11-22 00:38:41 +000029</div>
Chris Lattner3d482502003-10-02 04:57:28 +000030
Chris Lattner06971182010-04-13 06:37:00 +000031<!--
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000032<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.7
33release.<br>
34You may prefer the
35<a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6
Chris Lattner06971182010-04-13 06:37:00 +000036Release Notes</a>.</h1>-->
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000037
Chris Lattner3d482502003-10-02 04:57:28 +000038<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +000039<div class="doc_section">
40 <a name="intro">Introduction</a>
41</div>
Chris Lattner3d482502003-10-02 04:57:28 +000042<!-- *********************************************************************** -->
43
Misha Brukman80731b92003-11-22 00:38:41 +000044<div class="doc_text">
45
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000046<p>This document contains the release notes for the LLVM Compiler
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000047Infrastructure, release 2.7. Here we describe the status of LLVM, including
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000048major improvements from the previous release and significant known problems.
Mikhail Glushenkov25422542009-03-01 18:09:47 +000049All LLVM releases may be downloaded from the <a
Chris Lattner1e4d5bc2008-10-13 17:57:36 +000050href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner62495762003-10-02 16:38:05 +000051
Chris Lattnerb5bb5972004-12-07 08:04:13 +000052<p>For more information about LLVM, including information about the latest
Chris Lattnera69595e2005-10-29 07:07:09 +000053release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattnere7525b52003-10-07 21:38:31 +000054web site</a>. If you have questions or comments, the <a
Chris Lattner0b1c9a52010-03-17 04:41:49 +000055href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
56Mailing List</a> is a good place to send them.</p>
Chris Lattner3d482502003-10-02 04:57:28 +000057
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +000058<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner0a1fd102007-09-21 03:54:09 +000059main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif355f81c2008-10-14 11:00:32 +000060current one. To see the release notes for a specific release, please see the
Chris Lattner0a1fd102007-09-21 03:54:09 +000061<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman80731b92003-11-22 00:38:41 +000062
63</div>
Chris Lattneraa61f412009-10-13 17:48:04 +000064
Chris Lattner3d482502003-10-02 04:57:28 +000065
Chris Lattneraa61f412009-10-13 17:48:04 +000066<!--
67Almost dead code.
68 include/llvm/Analysis/LiveValues.h => Dan
69 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
70 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner06971182010-04-13 06:37:00 +000071 ABCD, GEPSplitterPass
Chris Lattner89ea59d2010-01-16 21:25:13 +000072 MSIL backend?
Chris Lattner10a3cc42010-03-17 06:41:58 +000073 lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
Chris Lattneraa61f412009-10-13 17:48:04 +000074-->
75
76
Jeffrey Yasskin0830b972010-01-28 01:14:43 +000077<!-- Features that need text if they're finished for 2.7:
Chris Lattneraa61f412009-10-13 17:48:04 +000078 strong phi elim
Chris Lattner87e04952010-04-21 05:17:40 +000079 llvm.dbg.value: variable debug info for optimized code
Chris Lattneraa61f412009-10-13 17:48:04 +000080 loop dependence analysis
Chris Lattner2b8a52e2008-02-10 07:46:44 +000081 -->
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +000082
Chris Lattnerc4d68542008-10-12 19:47:48 +000083 <!-- for announcement email:
Chris Lattneraa61f412009-10-13 17:48:04 +000084 Logo web page.
85 llvm devmtg
86 compiler_rt
87 KLEE web page at klee.llvm.org
88 Many new papers added to /pubs/
Chris Lattner10a3cc42010-03-17 06:41:58 +000089 Mention gcc plugin.
Chris Lattnerd02da042009-02-25 06:34:50 +000090 -->
Chris Lattner2b8a52e2008-02-10 07:46:44 +000091
Chris Lattnerf5cd9862008-10-13 18:01:01 +000092<!-- *********************************************************************** -->
93<div class="doc_section">
94 <a name="subproj">Sub-project Status Update</a>
Chris Lattner625a3d82008-06-08 21:34:41 +000095</div>
Chris Lattnerf5cd9862008-10-13 18:01:01 +000096<!-- *********************************************************************** -->
Chris Lattner625a3d82008-06-08 21:34:41 +000097
98<div class="doc_text">
Chris Lattnerc75fd522008-06-08 21:58:17 +000099<p>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000100The LLVM 2.7 distribution currently consists of code from the core LLVM
Chris Lattneraa61f412009-10-13 17:48:04 +0000101repository (which roughly includes the LLVM optimizers, code generators
102and supporting tools), the Clang repository and the llvm-gcc repository. In
103addition to this code, the LLVM Project includes other sub-projects that are in
104development. Here we include updates on these subprojects.
Bill Wendlingf170d2e2009-03-02 04:28:57 +0000105</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000106
Chris Lattnerc75fd522008-06-08 21:58:17 +0000107</div>
108
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000109
Chris Lattnerc75fd522008-06-08 21:58:17 +0000110<!--=========================================================================-->
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000111<div class="doc_subsection">
Chris Lattner44c09cd2008-10-13 18:11:54 +0000112<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000113</div>
114
115<div class="doc_text">
116
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000117<p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000118
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000119<p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
Bill Wendlingef362462008-10-27 09:27:33 +0000120
Daniel Dunbarc11b40f2008-10-14 23:25:09 +0000121<ul>
Daniel Dunbareb4bc7f2010-03-25 16:09:18 +0000122<li>FIXME: C++! Include a link to cxx_compatibility.html</li>
123
124<li>FIXME: Static Analyzer improvements?</li>
125
126<li>CIndex API and Python bindings: Clang now includes a C API as part of the
127CIndex library. Although we make make some changes to the API in the future, it
128is intended to be stable and has been designed for use by external projects. See
129the Clang
130doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
131documentation for more details. The CIndex API also includings an preliminary
132set of Python bindings.</li>
133
134<li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
135ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
136suitable for use as a a beta quality ARM compiler.</li>
Bill Wendling87adbe42009-03-02 04:28:18 +0000137</ul>
Chris Lattner44c09cd2008-10-13 18:11:54 +0000138</div>
139
140<!--=========================================================================-->
141<div class="doc_subsection">
142<a name="clangsa">Clang Static Analyzer</a>
143</div>
144
145<div class="doc_text">
146
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000147<p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also
Ted Kremenekc11fae82009-02-27 07:01:32 +0000148includes an early stage static source code analysis tool for <a
149href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Chris Lattneraa61f412009-10-13 17:48:04 +0000150in C and Objective-C programs. The tool performs checks to find
Ted Kremenekc11fae82009-02-27 07:01:32 +0000151bugs that occur on a specific path within a program.</p>
Chris Lattnerbcffa5a2008-10-14 00:52:49 +0000152
Chris Lattnerc871bac2010-03-17 04:02:39 +0000153<p>In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...</p>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000154
155</div>
156
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000157<!--=========================================================================-->
158<div class="doc_subsection">
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000159<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000160</div>
161
162<div class="doc_text">
163<p>
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000164The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattneraa61f412009-10-13 17:48:04 +0000165a JVM and a CLI Virtual Machine (Microsoft .NET is an
166implementation of the CLI) using LLVM for static and just-in-time
167compilation.</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000168
Chris Lattneraa61f412009-10-13 17:48:04 +0000169<p>
Chris Lattneref2e5732010-03-29 18:34:13 +0000170With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
171virtual machines. VMKit now offers precise and efficient garbage collection with
172multi-threading support, thanks to the MMTk memory management toolkit, as well
173as just in time and ahead of time compilation with LLVM. The major changes in
174VMKit 0.27 are:</p>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000175
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000176<ul>
177
Chris Lattneref2e5732010-03-29 18:34:13 +0000178<li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
179 The first collector to be ported is the MarkSweep collector, which is precise,
180 and drastically improves the performance of VMKit.</li>
181<li>Line number information in the JVM: by using the debug metadata of LLVM, the
182 JVM now supports precise line number information, useful when printing a stack
183 trace.</li>
184<li>Interface calls in the JVM: we implemented a variant of the Interface Method
185 Table technique for interface calls in the JVM.
186</li>
Nicolas Geoffraye5ec9322008-10-14 19:23:04 +0000187
188</ul>
Chris Lattnerf5cd9862008-10-13 18:01:01 +0000189</div>
190
Chris Lattneraa61f412009-10-13 17:48:04 +0000191
192<!--=========================================================================-->
193<div class="doc_subsection">
194<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
195</div>
196
197<div class="doc_text">
198<p>
199The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
200is a simple library that provides an implementation of the low-level
201target-specific hooks required by code generation and other runtime components.
202For example, when compiling for a 32-bit target, converting a double to a 64-bit
203unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
204function. The compiler-rt library provides highly optimized implementations of
205this and other low-level routines (some are 3x faster than the equivalent
206libgcc routines).</p>
207
208<p>
209All of the code in the compiler-rt project is available under the standard LLVM
Chris Lattner87e04952010-04-21 05:17:40 +0000210License, a "BSD-style" license. New in LLVM 2.7: compiler_rt now
211supports ARM targets.</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000212
213</div>
214
215<!--=========================================================================-->
216<div class="doc_subsection">
Duncan Sands92452b92010-04-02 09:23:15 +0000217<a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
Chris Lattneraa61f412009-10-13 17:48:04 +0000218</div>
219
220<div class="doc_text">
221<p>
Duncan Sands92452b92010-04-02 09:23:15 +0000222<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
223gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
224gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
225whatsoever (currently one small patch is needed). This is thanks to the new
226<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
227makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
228which is nothing more than a dynamic library which conforms to the gcc plugin
229interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
230instead of the gcc optimizers, and the LLVM code generators instead of the gcc
231code generators, just like llvm-gcc. To use it, you add
232"-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
233becomes llvm-gcc-4.5!
234</p>
235
236<p>
237DragonEgg is still a work in progress. Currently C works very well, while C++,
238Ada and Fortran work fairly well. All other languages either don't work at all,
239or only work poorly. For the moment only the x86-32 and x86-64 targets are
Duncan Sands4dd125e2010-04-20 19:40:58 +0000240supported, and only on linux and darwin (darwin needs an additional gcc patch).
Duncan Sands92452b92010-04-02 09:23:15 +0000241</p>
242
243<p>
Duncan Sands4dd125e2010-04-20 19:40:58 +0000244The first dragonegg release will occur shortly after llvm-2.7 is released.
Chris Lattneraa61f412009-10-13 17:48:04 +0000245</p>
246
247</div>
248
249
250<!--=========================================================================-->
251<div class="doc_subsection">
252<a name="mc">llvm-mc: Machine Code Toolkit</a>
253</div>
254
255<div class="doc_text">
256<p>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000257The LLVM Machine Code (MC) Toolkit project is ...
Chris Lattneraa61f412009-10-13 17:48:04 +0000258</p>
259
260</div>
261
262
Chris Lattner53e06f92009-02-26 22:33:38 +0000263<!-- *********************************************************************** -->
264<div class="doc_section">
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000265 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
Chris Lattner53e06f92009-02-26 22:33:38 +0000266</div>
267<!-- *********************************************************************** -->
268
Chris Lattneraa61f412009-10-13 17:48:04 +0000269<div class="doc_text">
270
271<p>An exciting aspect of LLVM is that it is used as an enabling technology for
272 a lot of other language and tools projects. This section lists some of the
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000273 projects that have already been updated to work with LLVM 2.7.</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000274</div>
275
Chris Lattner53e06f92009-02-26 22:33:38 +0000276<!--=========================================================================-->
277<div class="doc_subsection">
278<a name="pure">Pure</a>
279</div>
280
281<div class="doc_text">
282<p>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000283<a href="http://pure-lang.googlecode.com/">Pure</a>
284is an algebraic/functional programming language based on term rewriting.
Chris Lattner53e06f92009-02-26 22:33:38 +0000285Programs are collections of equations which are used to evaluate expressions in
286a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000287lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattner53e06f92009-02-26 22:33:38 +0000288built-in list and matrix support (including list and matrix comprehensions) and
289an easy-to-use C interface. The interpreter uses LLVM as a backend to
290 JIT-compile Pure programs to fast native code.</p>
291
Chris Lattner6aba4862010-03-17 17:25:49 +0000292<p>Pure versions 0.43 and later have been tested and are known to work with
293LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
294
Chris Lattner53e06f92009-02-26 22:33:38 +0000295</div>
296
Chris Lattnerfb23a962009-02-28 18:58:01 +0000297<!--=========================================================================-->
298<div class="doc_subsection">
299<a name="RoadsendPHP">Roadsend PHP</a>
300</div>
301
302<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000303<p>
304<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Chris Lattner0c72d8f2009-03-02 19:07:24 +0000305source implementation of the PHP programming
Chris Lattneraa61f412009-10-13 17:48:04 +0000306language that uses LLVM for its optimizer, JIT and static compiler. This is a
Chris Lattnerc871bac2010-03-17 04:02:39 +0000307reimplementation of an earlier project that is now based on LLVM.
Chris Lattner6aba4862010-03-17 17:25:49 +0000308</p>
Chris Lattnerfb23a962009-02-28 18:58:01 +0000309</div>
Chris Lattner53e06f92009-02-26 22:33:38 +0000310
Chris Lattneraa61f412009-10-13 17:48:04 +0000311<!--=========================================================================-->
312<div class="doc_subsection">
313<a name="UnladenSwallow">Unladen Swallow</a>
314</div>
315
316<div class="doc_text">
317<p>
318<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
319branch of <a href="http://python.org/">Python</a> intended to be fully
320compatible and significantly faster. It uses LLVM's optimization passes and JIT
Chris Lattner5b59a732010-03-18 06:52:15 +0000321compiler.
Chris Lattnerc871bac2010-03-17 04:02:39 +0000322</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000323</div>
324
325<!--=========================================================================-->
326<div class="doc_subsection">
Chris Lattnerb4a02792010-03-29 17:50:39 +0000327<a name="tce">TTA-based Codesign Environment (TCE)</a>
328</div>
329
330<div class="doc_text">
331<p>
332<a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
333application-specific processors (ASP) based on the Transport triggered
334architecture (TTA). The toolset provides a complete co-design flow from C/C++
335programs down to synthesizable VHDL and parallel program binaries. Processor
336customization points include the register files, function units, supported
337operations, and the interconnection network.</p>
338
339<p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
340independent optimizations and also for parts of code generation. It generates
341new LLVM-based code generators "on the fly" for the designed TTA processors and
342loads them in to the compiler backend as runtime libraries to avoid per-target
343recompilation of larger parts of the compiler chain.</p>
344
345</div>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000346
John Criswell9003e0f2010-04-06 14:52:14 +0000347<!--=========================================================================-->
348<div class="doc_subsection">
349<a name="safecode">SAFECode Compiler</a>
350</div>
351
352<div class="doc_text">
353<p>
354<a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
355compiler built using LLVM. It takes standard, unannotated C code, analyzes the
356code to ensure that memory accesses and array indexing operations are safe, and
357instruments the code with run-time checks when safety cannot be proven
358statically.
359</p>
360</div>
361
362
Chris Lattnerc75fd522008-06-08 21:58:17 +0000363<!-- *********************************************************************** -->
364<div class="doc_section">
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000365 <a name="whatsnew">What's New in LLVM 2.7?</a>
Chris Lattnerc75fd522008-06-08 21:58:17 +0000366</div>
367<!-- *********************************************************************** -->
368
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000369<div class="doc_text">
370
Chris Lattneraa61f412009-10-13 17:48:04 +0000371<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000372minor improvements. Some of the major improvements and new features are listed
373in this section.
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000374</p>
Chris Lattneraa61f412009-10-13 17:48:04 +0000375
Chris Lattner87e04952010-04-21 05:17:40 +0000376<p>In addition to changes to the code, between LLVM 2.6 and 2.7, a number of
377organization changes have happened:
378</p>
379
380<ul>
381<li>LLVM has a new <a href="http://llvm.org/Logo.html">official Logo</a>!</li>
382
383<li><a href="http://llvm.org">llvm.org</a> is now hosted on a new (and much
384faster) server. It is still hosted as the University of Illinois.</li>
385
386<li>Ted Kremenek and Doug Gregor have stepped forward as <a
387 href="http://llvm.org/docs/DeveloperPolicy.html#owners">Code Owners</a> of the
388 Clang static analyzer and the Clang Frontend, respectively.</li>
389
390<li>The LLVM web pages are now checked into the SVN server, in the "www",
391 "www-pubs" and "www-releases" SVN modules. Previously they were hidden in a
392 largely inaccessible old CVS server.</p>
393</ul>
Chris Lattnerb7bc2aa2008-06-08 22:59:35 +0000394</div>
395
Chris Lattnerc75fd522008-06-08 21:58:17 +0000396<!--=========================================================================-->
Chris Lattner625a3d82008-06-08 21:34:41 +0000397<div class="doc_subsection">
Chris Lattnercdc44ed2008-02-06 18:00:06 +0000398<a name="majorfeatures">Major New Features</a>
399</div>
400
401<div class="doc_text">
402
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000403<p>LLVM 2.7 includes several major new capabilities:</p>
Chris Lattner97beb512007-05-14 06:56:09 +0000404
405<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000406<li>New MicroBlaze backend. http://en.wikipedia.org/wiki/MicroBlaze</li>
407
408<li>Extensible metadata solid.</li>
409
410<li>Debug info improvements: using metadata instead of llvm.dbg global variables.
411This brings several enhancements including improved compile times.</li>
412
413<li>Indirect branch + address of label (blog post), particularly useful for
414interpreters.</li>
415
416<li>New instruction selector.</li>
417
Chris Lattner458e79f2008-02-10 08:18:42 +0000418</ul>
Chris Lattner408f7912010-04-16 06:20:22 +0000419libllvm2.7.so?? configure with --enable-shared
Chris Lattner87e04952010-04-21 05:17:40 +0000420MC encoding and disassembler apis.
421MC Disassembler (with blog post), MCInstPrinter. Many X86 backend and AsmPrinter simplifications
422Can transcode from GAS to intel syntax with "llvm-mc foo.s -output-asm-variant=1"
Chris Lattner408f7912010-04-16 06:20:22 +0000423
Chris Lattnere1c1eda2010-03-29 18:39:28 +0000424
Chris Lattner10a3cc42010-03-17 06:41:58 +0000425
Chris Lattner97beb512007-05-14 06:56:09 +0000426</div>
427
Chris Lattner0a1fd102007-09-21 03:54:09 +0000428<!--=========================================================================-->
429<div class="doc_subsection">
Chris Lattnerd1094e02009-03-02 02:37:32 +0000430<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000431</div>
432
433<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000434<p>LLVM IR has several new features for better support of new targets and that
435expose new optimization opportunities:</p>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000436
Chris Lattnerb7112222008-06-05 06:25:56 +0000437<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000438<li>New InlineHint and StackAlignment function attributes
439Half-float support in APFloat
440llvm.objectsize.
441New llvm/Support/Regex.h API. FileCheck now does regex's
442Pre-Alpha support for unions in IR.
443dbgs() and -debug-buffer-size=N
444</li>
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000445</ul>
Mikhail Glushenkov024f7cf2008-10-13 02:08:34 +0000446
Chris Lattnerdd6acc02008-02-10 08:17:19 +0000447</div>
448
449<!--=========================================================================-->
450<div class="doc_subsection">
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000451<a name="optimizer">Optimizer Improvements</a>
452</div>
453
454<div class="doc_text">
455
Chris Lattneraa61f412009-10-13 17:48:04 +0000456<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattner25879d72008-10-13 21:50:36 +0000457release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner2b8a52e2008-02-10 07:46:44 +0000458
459<ul>
460
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000461<li>...</li>
Chris Lattner87e04952010-04-21 05:17:40 +0000462Inliner reuses arrays allocas when inlining multiple callers to reduce stack usage.
463Optimal Edge Profiling?
464Instcombine is now a library, has its own IRBuilder to simplify itself.
465Better code size analysis in loop unswitch, inliner code split out to a new
466 CodeMetrics class for reuse.
467Many changes to the pass ordering for improved optimization effectiveness.
468BasicAA improved to be less dependent on "type safe" pointers, it can now look
469 through bitcasts more aggressively.
470GVN PHI Translation improvements. blog post: http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html
471New SCEV AA pass: -scev-aa
472Target data now has notion of 'native' integer data types which optimizations can use.
473Opt now works conservatively if no target data is set (is this fully working?)
474New Analysis/InstructionSimplify.h interface for simplifying instructions that don't exist.
475Jump threading is now much more aggressive at simplifying correlated
476 conditionals and threading blocks with otherwise complex logic. CondProp pass
477 removed (functionality merged into jump threading).
478New SSAUpdater and MachineSSAUpdater classes for unstructured ssa updating,
479 changed jump threading, GVN, etc to use it which simplified them and speed
480 them up.
481
Chris Lattnerd1094e02009-03-02 02:37:32 +0000482
Chris Lattneraa61f412009-10-13 17:48:04 +0000483</ul>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000484
Chris Lattneraa61f412009-10-13 17:48:04 +0000485</div>
Chris Lattnerd1094e02009-03-02 02:37:32 +0000486
Chris Lattnerd1094e02009-03-02 02:37:32 +0000487
Chris Lattneraa61f412009-10-13 17:48:04 +0000488<!--=========================================================================-->
489<div class="doc_subsection">
490<a name="executionengine">Interpreter and JIT Improvements</a>
491</div>
Chris Lattner25879d72008-10-13 21:50:36 +0000492
Chris Lattneraa61f412009-10-13 17:48:04 +0000493<div class="doc_text">
494
495<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000496<li>The JIT now supports generating debug information, which is compatible with
497the new GDB 7.0 (and later) interfaces for registering debug info for
498dynamically generated code.</li>
499
Jeffrey Yasskin9fb8ce82010-01-29 19:10:38 +0000500<li>The JIT now <a
501href="http://llvm.org/viewvc/llvm-project?view=rev&revision=85295">defaults
502to compiling eagerly</a> to avoid a race condition in the lazy JIT.
503Clients that still want the lazy JIT can switch it on by calling
504<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
Chris Lattner87e04952010-04-21 05:17:40 +0000505
Jeffrey Yasskine0913882010-02-11 01:07:39 +0000506<li>It is now possible to create more than one JIT instance in the same process.
507These JITs can generate machine code in parallel,
508although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
509still have to obey the other threading restrictions</a>.</li>
Chris Lattner87e04952010-04-21 05:17:40 +0000510
Chris Lattner7795ea92008-06-08 02:45:07 +0000511</ul>
512
513</div>
514
515<!--=========================================================================-->
516<div class="doc_subsection">
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000517<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner7795ea92008-06-08 02:45:07 +0000518</div>
519
520<div class="doc_text">
521
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000522<p>We have put a significant amount of work into the code generator
523infrastructure, which allows us to implement more aggressive algorithms and make
524it run faster:</p>
Chris Lattner7795ea92008-06-08 02:45:07 +0000525
526<ul>
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000527
Chris Lattner87e04952010-04-21 05:17:40 +0000528Code generator MC'ized except for debug info and EH.
529
530New CodeGen Level CSE
531Combiner-AA improvements, why not on by default?
532Pre-regalloc tail duplication
533New LSR with "full strength reduction" mode. Description?
534Codegen level OptimizeExtsPass pass, takes advantage of x86 subregs.
535Support for the GCC option -fno-schedule-insns
536non-temporal load/store
537MachineSSAUpdater.h
538X86 and XCore supports returning arbitrary return values, returning too many values is
539 supported by returning through a hidden pointer.
540verbose-asm now produces information about spill slots and loop nests
541GHC Haskell ABI / calling conv support.
542Many improvements to debug info
543
544
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000545<li>...</li>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000546</ul>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000547</div>
548
Chris Lattnerd1094e02009-03-02 02:37:32 +0000549<!--=========================================================================-->
550<div class="doc_subsection">
551<a name="x86">X86-32 and X86-64 Target Improvements</a>
552</div>
553
554<div class="doc_text">
555<p>New features of the X86 target include:
556</p>
557
558<ul>
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000559
Chris Lattner87e04952010-04-21 05:17:40 +0000560<li>PostRA scheduler for X86?</li>
561<li>x86 sibcall / tailcall optimization in CCC mode.</li>
562<li>X86: XMM subreg modeling for extraction of the low element.</li>
Chris Lattnerd434bfb2009-03-02 03:24:11 +0000563
Chris Lattnerd1094e02009-03-02 02:37:32 +0000564</ul>
565
Chris Lattnerd1094e02009-03-02 02:37:32 +0000566</div>
Chris Lattner0a1fd102007-09-21 03:54:09 +0000567
568<!--=========================================================================-->
569<div class="doc_subsection">
Chris Lattneraa61f412009-10-13 17:48:04 +0000570<a name="ARM">ARM Target Improvements</a>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000571</div>
572
573<div class="doc_text">
Chris Lattneraa61f412009-10-13 17:48:04 +0000574<p>New features of the ARM target include:
575</p>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000576
577<ul>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000578
Chris Lattner87e04952010-04-21 05:17:40 +0000579<li>complete llvm-gcc NEON support.</li>
580<li>ARM/Thumb using reg scavenging for stack object address materialization
581 (PEI).</li>
582<li>The ARM backend now has good support for ARMv4 backend (tested on StrongARM
583 hardware), previously only supported ARMv4T and newer.</li>
584<li>ARM backend generates instructions in unified assembly syntax.</li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000585</ul>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000586
Chris Lattnerc92d7692009-03-01 02:30:21 +0000587
Chris Lattneraa61f412009-10-13 17:48:04 +0000588</div>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000589
Chris Lattneraa61f412009-10-13 17:48:04 +0000590<!--=========================================================================-->
591<div class="doc_subsection">
592<a name="OtherTarget">Other Target Specific Improvements</a>
593</div>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000594
Chris Lattneraa61f412009-10-13 17:48:04 +0000595<div class="doc_text">
596<p>New features of other targets include:
597</p>
598
599<ul>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000600<li>...</li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000601</ul>
602
603</div>
604
605<!--=========================================================================-->
606<div class="doc_subsection">
607<a name="newapis">New Useful APIs</a>
608</div>
609
610<div class="doc_text">
611
612<p>This release includes a number of new APIs that are used internally, which
613 may also be useful for external clients.
614</p>
615
616<ul>
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000617<li>...</li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000618</ul>
619
620
621</div>
622
623<!--=========================================================================-->
624<div class="doc_subsection">
625<a name="otherimprovements">Other Improvements and New Features</a>
626</div>
627
628<div class="doc_text">
629<p>Other miscellaneous features include:</p>
630
631<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000632<li>LLVM command line tools now overwrite their output by default, before they
633 would only do this with -f. This makes them more convenient to use, and
634 behave more like standard unix tools.</li>
635
636<li>The opt and llc tools now autodetect whether their input is a .ll or .bc
637 file, and automatically do the right thing. This means you don't need to
638 explicitly use the llvm-as tool for most things.</li>
Chris Lattnerc92d7692009-03-01 02:30:21 +0000639</ul>
640
641</div>
642
Chris Lattner6cb64032008-06-05 08:02:49 +0000643
644<!--=========================================================================-->
645<div class="doc_subsection">
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000646<a name="changes">Major Changes and Removed Features</a>
647</div>
648
649<div class="doc_text">
650
Chris Lattner934e2d42008-10-13 22:06:31 +0000651<p>If you're already an LLVM user or developer with out-of-tree changes based
Jeffrey Yasskin0830b972010-01-28 01:14:43 +0000652on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
Chris Lattner934e2d42008-10-13 22:06:31 +0000653from the previous release.</p>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000654
655<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000656
657<li>
658The Andersen's alias analysis ("anders-aa") pass, the Predicate Simplifier
659("predsimplify") pass, the LoopVR pass, the GVNPRE pass, and the random sampling
660profiling ("rsprofiling") passes have all been removed. They were not being
661actively maintained and had substantial problems. If you are interested in
662these components, you are welcome to ressurect them from SVN, fix the
663correctness problems, and resubmit them to mainline.</li>
664
665<li>LLVM now defaults to building most libraries with RTTI turned off, providing
666a code size reduction. Packagers who are interested in building LLVM to support
667plugins that require RTTI information should build with "make REQUIRE_RTTI=1"
668and should read the new <a href="Packaging.html">Advice on Packaging LLVM</a>
669document.</li>
670
Jeffrey Yasskin914050b2010-02-09 23:03:44 +0000671<li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
672if you have it installed. This makes it more likely that an LLVM built on one
673system will work when copied to a similar system. To use <tt>libffi</tt>,
Chris Lattner87e04952010-04-21 05:17:40 +0000674configure with <tt>--enable-libffi</tt></li>.
Chris Lattner934e2d42008-10-13 22:06:31 +0000675
Chris Lattner87e04952010-04-21 05:17:40 +0000676<li>Debug information uses a completely different representation, an LLVM 2.6
677.bc file should work with LLVM 2.7, but debug info won't come forward.</li>
678
679<li>The LLVM 2.6 (and earlier) "malloc" and "free" instructions got removed,
680 along with LowerAllocations pass. Now you should just use a call to the
681 malloc and free functions in libc. These calls are optimized as well as
682 the old instructions were.</li>
683</ul>
Chris Lattner934e2d42008-10-13 22:06:31 +0000684
685<p>In addition, many APIs have changed in this release. Some of the major LLVM
686API changes are:</p>
687
688<ul>
Chris Lattner87e04952010-04-21 05:17:40 +0000689<li>Just about everything has been converted to use raw_ostream instead of
690 std::ostream.</li>
691<li>llvm/ADT/iterator.h has been removed, just use &lt;iterator&gt;
692 instead.</li>
693<li>The Streams.h file and "DOUT" got removed, use "DEBUG(errs() &lt;&lt; ...);"
694 instead.</li>
Jeffrey Yasskin4a8b1da2010-01-28 01:41:20 +0000695<li><tt>ModuleProvider</tt> has been <a
696href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
697and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
698Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
699replace <tt>getBitcodeModuleProvider</tt> with
700<tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
701functions that used to accept <tt>ModuleProvider</tt>. Clients who
702wrote their own <tt>ModuleProvider</tt>s will need to derive from
703<tt>GVMaterializer</tt> instead and use
704<tt>Module::setMaterializer</tt> to attach it to a
705<tt>Module</tt>.</li>
706
707<li><tt>GhostLinkage</tt> has given up the ghost.
708<tt>GlobalValue</tt>s that have not yet been read from their backing
709storage have the same linkage they will have after being read in.
710Clients must replace calls to
711<tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
712<tt>GlobalValue::isMaterializable</tt>.</li>
Daniel Dunbar1e96fca2010-02-10 04:09:52 +0000713
Daniel Dunbar3e255da2010-02-14 01:47:19 +0000714<li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
715to <tt>llvm/System/DataTypes.h</tt>.</li>
716
Duncan Sands80c430a2010-02-17 17:20:17 +0000717<li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
718<tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
719<tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
720<tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
Devang Pateldbf83832008-10-14 20:03:43 +0000721</ul>
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000722
Chris Lattner1e4d5bc2008-10-13 17:57:36 +0000723</div>
724
725
726
Chris Lattner62495762003-10-02 16:38:05 +0000727<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000728<div class="doc_section">
729 <a name="portability">Portability and Supported Platforms</a>
730</div>
Chris Lattner62495762003-10-02 16:38:05 +0000731<!-- *********************************************************************** -->
732
Misha Brukman80731b92003-11-22 00:38:41 +0000733<div class="doc_text">
734
John Criswell64307722004-12-08 20:35:47 +0000735<p>LLVM is known to work on the following platforms:</p>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000736
737<ul>
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000738<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattneraa61f412009-10-13 17:48:04 +0000739 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
740 systems).</li>
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000741<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
Chris Lattneraa61f412009-10-13 17:48:04 +0000742 and 64-bit modes.</li>
Chris Lattnercdc44ed2008-02-06 18:00:06 +0000743<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Chris Lattnerbee7b322007-05-23 04:39:32 +0000744<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
745 support is available for native builds with Visual C++).</li>
Chris Lattner51948622009-10-16 16:30:58 +0000746<li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
John Criswelld5234922005-05-13 20:28:15 +0000747<li>Alpha-based machines running Debian GNU/Linux.</li>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000748</ul>
749
Chris Lattner618a99f2008-06-05 06:57:39 +0000750<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Brian Gaekee3e557e2004-05-09 05:28:35 +0000751to the machine and operating system on which it is built. However, minor
752porting may be required to get LLVM to work on new platforms. We welcome your
753portability patches and reports of successful builds or error messages.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000754
Misha Brukman80731b92003-11-22 00:38:41 +0000755</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000756
757<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000758<div class="doc_section">
759 <a name="knownproblems">Known Problems</a>
760</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000761<!-- *********************************************************************** -->
762
Misha Brukman80731b92003-11-22 00:38:41 +0000763<div class="doc_text">
764
Mikhail Glushenkov25422542009-03-01 18:09:47 +0000765<p>This section contains significant known problems with the LLVM system,
Chris Lattner2a092392008-11-10 05:40:34 +0000766listed by component. If you run into a problem, please check the <a
Chris Lattnera69595e2005-10-29 07:07:09 +0000767href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000768there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000769
Chris Lattner6aba4862010-03-17 17:25:49 +0000770<ul>
Chris Lattneraa61f412009-10-13 17:48:04 +0000771<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
772using the stock GCC 3.x.x series 'out the box',
Chris Lattner6e41c792009-11-03 21:50:09 +0000773See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
Chris Lattneraa61f412009-10-13 17:48:04 +0000774However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
775for x86/x86-64 has been made available from the third party AuroraUX Project
776that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
777</ul>
778
Misha Brukman80731b92003-11-22 00:38:41 +0000779</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000780
Chris Lattnerb911de42004-03-14 02:03:02 +0000781<!-- ======================================================================= -->
782<div class="doc_subsection">
783 <a name="experimental">Experimental features included with this release</a>
784</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000785
Chris Lattnerb911de42004-03-14 02:03:02 +0000786<div class="doc_text">
787
Misha Brukmanfa50a222004-05-12 21:46:05 +0000788<p>The following components of this LLVM release are either untested, known to
789be broken or unreliable, or are in early development. These components should
790not be relied on, and bugs should not be filed against them, but they may be
791useful to some people. In particular, if you would like to work on one of these
Chris Lattnere38ac152008-02-12 06:29:45 +0000792components, please contact us on the <a
793href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerb911de42004-03-14 02:03:02 +0000794
795<ul>
Wesley Peck3aa84e52010-03-18 14:31:30 +0000796<li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
797 backends are experimental.</li>
Bill Wendling89cd82f2009-03-02 07:54:14 +0000798<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
Chris Lattner0b1c9a52010-03-17 04:41:49 +0000799 supported value for this option. The MachO writer is experimental, and
800 works much better in mainline SVN.</li>
Chris Lattnerb911de42004-03-14 02:03:02 +0000801</ul>
802
803</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000804
Misha Brukman80731b92003-11-22 00:38:41 +0000805<!-- ======================================================================= -->
806<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000807 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswell3bdbd302005-11-08 21:11:33 +0000808</div>
809
810<div class="doc_text">
811
812<ul>
Anton Korobeynikov486c7d32008-06-08 10:24:13 +0000813 <li>The X86 backend does not yet support
814 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
815 floating point stack</a>. It supports the 'f' and 't' constraints, but not
816 'u'.</li>
Chris Lattnerb076b002008-06-08 21:19:07 +0000817 <li>The X86 backend generates inefficient floating point code when configured
818 to generate code for systems that don't have SSE2.</li>
Duncan Sands0bc15262008-06-08 19:38:43 +0000819 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellea03c9d2009-03-02 15:28:15 +0000820 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
821 runtime currently due
Anton Korobeynikov486c7d32008-06-08 10:24:13 +0000822 to <a href="http://llvm.org/PR2255">several</a>
John Criswellea03c9d2009-03-02 15:28:15 +0000823 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
824 the
825 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
Dan Gohman721b3722008-06-08 23:05:11 +0000826 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattnerd1094e02009-03-02 02:37:32 +0000827 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman721b3722008-06-08 23:05:11 +0000828 argument constructs on X86-64 by lowering them manually.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000829</ul>
830
831</div>
832
833<!-- ======================================================================= -->
834<div class="doc_subsection">
835 <a name="ppc-be">Known problems with the PowerPC back-end</a>
836</div>
837
838<div class="doc_text">
839
840<ul>
Nicolas Geoffray77d99502007-05-15 09:21:28 +0000841<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattnerbee7b322007-05-23 04:39:32 +0000842compilation, and lacks support for debug information.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000843</ul>
844
845</div>
846
847<!-- ======================================================================= -->
848<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000849 <a name="arm-be">Known problems with the ARM back-end</a>
850</div>
851
852<div class="doc_text">
853
854<ul>
Chris Lattneraa61f412009-10-13 17:48:04 +0000855<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
856and not well tested. Some features may not work at all, and the code quality
857may be poor in some cases.</li>
Chris Lattnerbee7b322007-05-23 04:39:32 +0000858<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands47fc0a22007-09-26 15:59:54 +0000859processors, thumb programs can crash or produce wrong
Chris Lattnerbee7b322007-05-23 04:39:32 +0000860results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellea03c9d2009-03-02 15:28:15 +0000861<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattner97beb512007-05-14 06:56:09 +0000862</li>
Chris Lattner97beb512007-05-14 06:56:09 +0000863</ul>
864
865</div>
866
867<!-- ======================================================================= -->
868<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000869 <a name="sparc-be">Known problems with the SPARC back-end</a>
870</div>
871
872<div class="doc_text">
873
874<ul>
John Criswellea03c9d2009-03-02 15:28:15 +0000875<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000876 support the 64-bit SPARC ABI (-m64).</li>
877</ul>
878
879</div>
880
881<!-- ======================================================================= -->
882<div class="doc_subsection">
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000883 <a name="mips-be">Known problems with the MIPS back-end</a>
884</div>
885
886<div class="doc_text">
887
888<ul>
Bruno Cardoso Lopes24eb3de2008-10-25 14:56:26 +0000889<li>64-bit MIPS targets are not supported yet.</li>
890</ul>
891
892</div>
893
894<!-- ======================================================================= -->
895<div class="doc_subsection">
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000896 <a name="alpha-be">Known problems with the Alpha back-end</a>
897</div>
898
899<div class="doc_text">
900
901<ul>
902
903<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
904appropriate nops inserted to ensure restartability.</li>
905
John Criswell3bdbd302005-11-08 21:11:33 +0000906</ul>
907</div>
908
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000909<!-- ======================================================================= -->
910<div class="doc_subsection">
Chris Lattner97beb512007-05-14 06:56:09 +0000911 <a name="c-be">Known problems with the C back-end</a>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000912</div>
913
914<div class="doc_text">
915
916<ul>
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000917<li><a href="http://llvm.org/PR802">The C backend has only basic support for
918 inline assembly code</a>.</li>
Chris Lattner8e061162007-09-26 06:01:35 +0000919<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
920 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif75b2f762009-03-02 12:02:51 +0000921 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandse09506a2008-02-10 13:40:55 +0000922<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands3aa36732009-02-25 11:51:54 +0000923<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattnerb81f10e2006-11-18 07:51:14 +0000924</ul>
925
926</div>
John Criswell3bdbd302005-11-08 21:11:33 +0000927
Misha Brukman80731b92003-11-22 00:38:41 +0000928
929<!-- ======================================================================= -->
930<div class="doc_subsection">
Chris Lattner0b1c9a52010-03-17 04:41:49 +0000931 <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000932</div>
Chris Lattner178f3db2003-10-02 05:07:23 +0000933
Misha Brukman80731b92003-11-22 00:38:41 +0000934<div class="doc_text">
Chris Lattner72a269f2006-03-03 00:34:26 +0000935
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000936<p>The only major language feature of GCC not supported by llvm-gcc is
937 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
938 are only supported on some targets. For example, trampolines are only
Duncan Sands56448462008-06-08 20:18:35 +0000939 supported on some targets (these are used when you take the address of a
940 nested function).</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000941
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000942<p>If you run into GCC extensions which are not supported, please let us know.
943</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000944
Misha Brukman80731b92003-11-22 00:38:41 +0000945</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000946
Misha Brukman80731b92003-11-22 00:38:41 +0000947<!-- ======================================================================= -->
948<div class="doc_subsection">
Chris Lattner7292fb12008-10-30 03:58:13 +0000949 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
950</div>
951
952<div class="doc_text">
Gabor Greife5f9d672008-11-04 21:50:59 +0000953<ul>
Chris Lattner7292fb12008-10-30 03:58:13 +0000954<li>Fortran support generally works, but there are still several unresolved bugs
Chris Lattneraa61f412009-10-13 17:48:04 +0000955 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
956 tools/gfortran component for details.</li>
Gabor Greife5f9d672008-11-04 21:50:59 +0000957</ul>
Chris Lattner7292fb12008-10-30 03:58:13 +0000958</div>
Misha Brukman80731b92003-11-22 00:38:41 +0000959
Chris Lattnere38ac152008-02-12 06:29:45 +0000960<!-- ======================================================================= -->
961<div class="doc_subsection">
Chris Lattnera1a4c9a2008-06-05 06:35:40 +0000962 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnere38ac152008-02-12 06:29:45 +0000963</div>
964
965<div class="doc_text">
John Criswellea03c9d2009-03-02 15:28:15 +0000966The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
967technology, and problems should be expected.
Chris Lattnere38ac152008-02-12 06:29:45 +0000968<ul>
Duncan Sands56448462008-06-08 20:18:35 +0000969<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswellea03c9d2009-03-02 15:28:15 +0000970to lack of trampoline support (pointers to nested functions) on other platforms.
971However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnere38ac152008-02-12 06:29:45 +0000972which does support trampolines.</li>
973<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sandsd34bf762009-02-25 11:59:06 +0000974This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
975exception handling, which is used internally by the compiler.
Chris Lattneraa61f412009-10-13 17:48:04 +0000976Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
Duncan Sandsaef747f2008-10-13 17:27:23 +0000977<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
978and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsd34bf762009-02-25 11:59:06 +0000979(c380004 also fails with gcc-4.2 mainline).
980If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
981causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sands2dbb00e2009-03-02 16:35:57 +0000982<li>Some GCC specific Ada tests continue to crash the compiler.</li>
Chris Lattneraa61f412009-10-13 17:48:04 +0000983<li>The <tt>-E</tt> binder option (exception backtraces)
Chris Lattnere38ac152008-02-12 06:29:45 +0000984<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
Chris Lattneraa61f412009-10-13 17:48:04 +0000985crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
Chris Lattnere38ac152008-02-12 06:29:45 +0000986<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
987or finish at a non-byte offset</a> in a record. Workaround: do not pack records
988or use representation clauses that result in a field of a non-discrete type
989starting or finishing in the middle of a byte.</li>
Chris Lattnerb076b002008-06-08 21:19:07 +0000990<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
991'main' as generated by the Ada binder to be invalid</a>.
992Workaround: hand edit the file to use pointers for <tt>argv</tt> and
993<tt>envp</tt> rather than integers.</li>
994<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
995ignored</a>.</li>
Chris Lattnere38ac152008-02-12 06:29:45 +0000996</ul>
997</div>
998
Chris Lattner3d482502003-10-02 04:57:28 +0000999<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +00001000<div class="doc_section">
1001 <a name="additionalinfo">Additional Information</a>
1002</div>
Chris Lattner3d482502003-10-02 04:57:28 +00001003<!-- *********************************************************************** -->
1004
Misha Brukman80731b92003-11-22 00:38:41 +00001005<div class="doc_text">
1006
Chris Lattnercb5596d2005-05-16 17:13:10 +00001007<p>A wide variety of additional information is available on the <a
Chris Lattnere0c1df42007-05-18 00:44:29 +00001008href="http://llvm.org">LLVM web page</a>, in particular in the <a
1009href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencerc7f87f22007-07-09 08:04:31 +00001010contains versions of the API documentation which is up-to-date with the
1011Subversion version of the source code.
Misha Brukman96158092005-03-30 19:14:24 +00001012You can access versions of these documents specific to this release by going
1013into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +00001014
Misha Brukman80731b92003-11-22 00:38:41 +00001015<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnera69595e2005-10-29 07:07:09 +00001016us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattnerb84f3322003-12-12 21:22:16 +00001017lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +00001018
Misha Brukman80731b92003-11-22 00:38:41 +00001019</div>
Chris Lattner3d482502003-10-02 04:57:28 +00001020
1021<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +00001022
Misha Brukman80731b92003-11-22 00:38:41 +00001023<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +00001024<address>
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Chris Lattnere0c1df42007-05-18 00:44:29 +00001030 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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