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Chris Lattnerbe2e1b52011-03-10 07:43:44 +00008 <title>LLVM 2.9 Release Notes</title>
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10<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +000011
NAKAMURA Takumic6319312011-04-05 21:55:14 +000012<h1 class="doc_title">LLVM 2.9 Release Notes</h1>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000013
Chris Lattner0e464a92010-03-17 04:02:39 +000014<img align=right src="http://llvm.org/img/DragonSmall.png"
Gabor Greifee2187a2010-04-22 10:21:43 +000015 width="136" height="136" alt="LLVM Dragon Logo">
Chris Lattner0e464a92010-03-17 04:02:39 +000016
Chris Lattner79c3fe12003-10-02 04:57:28 +000017<ol>
Misha Brukman500bc302003-11-22 00:38:41 +000018 <li><a href="#intro">Introduction</a></li>
Chris Lattner96a445e2008-10-13 18:01:01 +000019 <li><a href="#subproj">Sub-project Status Update</a></li>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000020 <li><a href="#externalproj">External Projects Using LLVM 2.9</a></li>
21 <li><a href="#whatsnew">What's New in LLVM 2.9?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +000022 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Dan Gohman44aa9212008-10-14 16:23:02 +000023 <li><a href="#knownproblems">Known Problems</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +000024 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +000025</ol>
26
Chris Lattner7911ce22004-05-23 21:07:27 +000027<div class="doc_author">
Dan Gohman44aa9212008-10-14 16:23:02 +000028 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Misha Brukman500bc302003-11-22 00:38:41 +000029</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +000030
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000031<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.9
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000032release.<br>
33You may prefer the
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000034<a href="http://llvm.org/releases/2.8/docs/ReleaseNotes.html">LLVM 2.8
Dan Gohmanb44f6c62010-05-03 23:51:05 +000035Release Notes</a>.</h1>
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000036
Chris Lattner79c3fe12003-10-02 04:57:28 +000037<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000038<h1>
Misha Brukman500bc302003-11-22 00:38:41 +000039 <a name="intro">Introduction</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000040</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +000041<!-- *********************************************************************** -->
42
Misha Brukman500bc302003-11-22 00:38:41 +000043<div class="doc_text">
44
Chris Lattnerf6662f92008-10-13 17:57:36 +000045<p>This document contains the release notes for the LLVM Compiler
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000046Infrastructure, release 2.9. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +000047major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +000048All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +000049href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +000050
Chris Lattner7506b1d2004-12-07 08:04:13 +000051<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000052release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000053web site</a>. If you have questions or comments, the <a
Chris Lattnerc66bfef2010-03-17 04:41:49 +000054href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
55Mailing List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000056
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000057<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +000058main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +000059current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +000060<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +000061
62</div>
Chris Lattner61358ab2009-10-13 17:48:04 +000063
Chris Lattnere4dc1962011-04-05 23:22:33 +000064<!-- Features that need text if they're finished for 3.1:
65 ARM EHABI
Chris Lattner914ce462010-04-22 06:28:20 +000066 combiner-aa?
Chris Lattner61358ab2009-10-13 17:48:04 +000067 strong phi elim
Chris Lattner61358ab2009-10-13 17:48:04 +000068 loop dependence analysis
Chris Lattnere07043c2010-09-29 05:30:03 +000069 CorrelatedValuePropagation
Chris Lattnere4dc1962011-04-05 23:22:33 +000070 lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
Chris Lattneracce85d2008-02-10 07:46:44 +000071 -->
Chris Lattnere07043c2010-09-29 05:30:03 +000072
Chris Lattner96a445e2008-10-13 18:01:01 +000073<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000074<h1>
Chris Lattner96a445e2008-10-13 18:01:01 +000075 <a name="subproj">Sub-project Status Update</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000076</h1>
Chris Lattner96a445e2008-10-13 18:01:01 +000077<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +000078
79<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +000080<p>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000081The LLVM 2.9 distribution currently consists of code from the core LLVM
Chris Lattner61358ab2009-10-13 17:48:04 +000082repository (which roughly includes the LLVM optimizers, code generators
83and supporting tools), the Clang repository and the llvm-gcc repository. In
84addition to this code, the LLVM Project includes other sub-projects that are in
85development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +000086</p>
Chris Lattner96a445e2008-10-13 18:01:01 +000087
Chris Lattner8348b472008-06-08 21:58:17 +000088</div>
89
Chris Lattner96a445e2008-10-13 18:01:01 +000090
Chris Lattner8348b472008-06-08 21:58:17 +000091<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000092<h2>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +000093<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000094</h2>
Chris Lattner8348b472008-06-08 21:58:17 +000095
96<div class="doc_text">
97
Chris Lattner095539f2010-04-26 17:42:18 +000098<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
99C++, and Objective-C languages. Clang aims to provide a better user experience
100through expressive diagnostics, a high level of conformance to language
101standards, fast compilation, and low memory use. Like LLVM, Clang provides a
102modular, library-based architecture that makes it suitable for creating or
103integrating with other development tools. Clang is considered a
Chris Lattnere07043c2010-09-29 05:30:03 +0000104production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
Chris Lattner1efe27e2011-04-06 00:45:11 +0000105(32- and 64-bit), and for darwin/arm targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000106
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000107<p>In the LLVM 2.9 time-frame, the Clang team has made many improvements in C,
108C++ and Objective-C support. C++ support is now generally rock solid, has
Chris Lattnerdf448a32011-04-06 00:56:12 +0000109been exercised on a broad variety of code, and has several new <a
110href="http://clang.llvm.org/cxx_status.html#cxx0x">C++'0x features</a>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000111implemented (such as rvalue references and variadic templates). LLVM 2.9 has
112also brought in a large range of bug fixes and minor features (e.g. __label__
113support), and is much more compatible with the Linux Kernel.</p>
114
115<p>If Clang rejects your code that is built with another compiler, please take a
116look at the <a href="http://clang.llvm.org/compatibility.html">language
117compatibility</a> guide to make sure the issue isn't intentional or a known
118issue.
119</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000120
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000121<ul>
122</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000123</div>
124
125<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000126<h2>
Duncan Sands528a5102011-04-04 11:09:08 +0000127<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000128</h2>
Chris Lattner61358ab2009-10-13 17:48:04 +0000129
130<div class="doc_text">
131<p>
Duncan Sands528a5102011-04-04 11:09:08 +0000132<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
133<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
134optimizers and code generators with LLVM's.
135Currently it requires a patched version of gcc-4.5.
136The plugin can target the x86-32 and x86-64 processor families and has been
137used successfully on the Darwin, FreeBSD and Linux platforms.
138The Ada, C, C++ and Fortran languages work well.
139The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is
140not known whether the compiled code actually works or not!
Duncan Sands749fd832010-04-02 09:23:15 +0000141</p>
142
143<p>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000144The 2.9 release has the following notable changes:
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000145<ul>
Duncan Sands528a5102011-04-04 11:09:08 +0000146<li>The plugin is much more stable when compiling Fortran.</li>
Chris Lattnerdf448a32011-04-06 00:56:12 +0000147<li>Inline assembly where an asm output is tied to an input of a different size
148is now supported in many more cases.</li>
Duncan Sands528a5102011-04-04 11:09:08 +0000149<li>Basic support for the __float128 type was added. It is now possible to
150generate LLVM IR from programs using __float128 but code generation does not
151work yet.</li>
152<li>Compiling Java programs no longer systematically crashes the plugin.</li>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000153</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000154
155</div>
156
Chris Lattner75547712010-10-03 23:49:06 +0000157<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000158<h2>
Chris Lattner75547712010-10-03 23:49:06 +0000159<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000160</h2>
Chris Lattner75547712010-10-03 23:49:06 +0000161
162<div class="doc_text">
163<p>
164The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
165is a simple library that provides an implementation of the low-level
166target-specific hooks required by code generation and other runtime components.
167For example, when compiling for a 32-bit target, converting a double to a 64-bit
168unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
169function. The compiler-rt library provides highly optimized implementations of
170this and other low-level routines (some are 3x faster than the equivalent
171libgcc routines).</p>
172
Chris Lattnerdf448a32011-04-06 00:56:12 +0000173<p>In the LLVM 2.9 timeframe, compiler_rt has had several minor changes for
174 better ARM support, and a fairly major license change. All of the code in the
175 compiler-rt project is now <a href="DeveloperPolicy.html#license">dual
176 licensed</a> under MIT and UIUC license, which allows you to use compiler-rt
177 in applications without the binary copyright reproduction clause. If you
178 prefer the LLVM/UIUC license, you are free to continue using it under that
179 license as well.</p>
Chris Lattner75547712010-10-03 23:49:06 +0000180
181</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000182
183<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000184<h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000185<a name="lldb">LLDB: Low Level Debugger</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000186</h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000187
188<div class="doc_text">
189<p>
Chris Lattner75547712010-10-03 23:49:06 +0000190<a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
191umbrella of projects. LLDB is a next generation, high-performance debugger. It
192is built as a set of reusable components which highly leverage existing
193libraries in the larger LLVM Project, such as the Clang expression parser, the
194LLVM disassembler and the LLVM JIT.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000195
196<p>
Chris Lattnerdf448a32011-04-06 00:56:12 +0000197LLDB is has advanced by leaps and bounds in the 2.9 timeframe. It is
198dramatically more stable and useful, and includes both a new <a
199href="http://lldb.llvm.org/tutorial.html">tutorial</a> and a <a
200href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with
201GDB</a>.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000202
203</div>
204
205<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000206<h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000207<a name="libc++">libc++: C++ Standard Library</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000208</h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000209
210<div class="doc_text">
211<p>
Tobias Grossercdce44b2010-10-06 21:07:30 +0000212<a href="http://libcxx.llvm.org/">libc++</a> is another new member of the LLVM
Chris Lattner75547712010-10-03 23:49:06 +0000213family. It is an implementation of the C++ standard library, written from the
214ground up to specifically target the forthcoming C++'0X standard and focus on
215delivering great performance.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000216
217<p>
Chris Lattner2009c492011-04-06 00:59:18 +0000218In the LLVM 2.9 timeframe, libc++ has had numerous bugs fixed, and is now being
219co-developed with Clang's C++'0x mode.</p>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000220
Chris Lattner2009c492011-04-06 00:59:18 +0000221<p>
222Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
223 licensed</a> under the MIT and UIUC license, allowing it to be used more
224 permissively.
Chris Lattnere07043c2010-09-29 05:30:03 +0000225</p>
226
227</div>
228
Chris Lattner61358ab2009-10-13 17:48:04 +0000229
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000230
231<!--=========================================================================-->
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000232<!--
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000233<h2>
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000234<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000235</h2>
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000236
237<div class="doc_text">
238<p>
239<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
240programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
241through the application and records state transitions that lead to fault
242states. This allows it to construct testcases that lead to faults and can even
243be used to verify some algorithms.
244</p>
245
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000246<p>UPDATE!</p>
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000247</div>-->
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000248
249
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000250<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000251<h1>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000252 <a name="externalproj">External Open Source Projects Using LLVM 2.9</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000253</h1>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000254<!-- *********************************************************************** -->
255
Chris Lattner61358ab2009-10-13 17:48:04 +0000256<div class="doc_text">
257
258<p>An exciting aspect of LLVM is that it is used as an enabling technology for
259 a lot of other language and tools projects. This section lists some of the
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000260 projects that have already been updated to work with LLVM 2.9.</p>
Chris Lattner7c8e7962010-04-26 17:38:10 +0000261</div>
262
Chris Lattner75547712010-10-03 23:49:06 +0000263
Chris Lattner3bfe57e2011-04-06 01:13:49 +0000264<!--=========================================================================-->
265<h2>Crack Programming Language</h2>
266
267<div class="doc_text">
268<p>
269<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide the
270ease of development of a scripting language with the performance of a compiled
271language. The language derives concepts from C++, Java and Python, incorporating
272object-oriented programming, operator overloading and strong typing.</p>
273</div>
274
275
276<!--=========================================================================-->
277<h2>TTA-based Codesign Environment (TCE)</h2>
278
279<div class="doc_text">
280<p>TCE is a toolset for designing application-specific processors (ASP) based on
281the Transport triggered architecture (TTA). The toolset provides a complete
282co-design flow from C/C++ programs down to synthesizable VHDL and parallel
283program binaries. Processor customization points include the register files,
284function units, supported operations, and the interconnection network.</p>
285
286<p>TCE uses Clang and LLVM for C/C++ language support, target independent
287optimizations and also for parts of code generation. It generates new LLVM-based
288code generators "on the fly" for the designed TTA processors and loads them in
289to the compiler backend as runtime libraries to avoid per-target recompilation
290of larger parts of the compiler chain.</p>
291</div>
292
293
294
295<!--=========================================================================-->
296<h2>PinaVM</h2>
297
298<div class="doc_text">
299<p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open
300source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many
301other front-ends, PinaVM actually executes the elaboration of the
302program analyzed using LLVM's JIT infrastructure. It later enriches the
303bitcode with SystemC-specific information.</p>
304</div>
305
306<!--=========================================================================-->
307<h2>Pure</h2>
308
309<div class="doc_text">
310<p><a href="http://pure-lang.googlecode.com/">Pure</a> is an
311 algebraic/functional
312 programming language based on term rewriting. Programs are collections
313 of equations which are used to evaluate expressions in a symbolic
314 fashion. The interpreter uses LLVM as a backend to JIT-compile Pure
315 programs to fast native code. Pure offers dynamic typing, eager and lazy
316 evaluation, lexical closures, a hygienic macro system (also based on
317 term rewriting), built-in list and matrix support (including list and
318 matrix comprehensions) and an easy-to-use interface to C and other
319 programming languages (including the ability to load LLVM bitcode
320 modules, and inline C, C++, Fortran and Faust code in Pure programs if
321 the corresponding LLVM-enabled compilers are installed).</p>
322
323<p>Pure version 0.47 has been tested and is known to work with LLVM 2.9
324 (and continues to work with older LLVM releases &gt;= 2.5).</p>
325</div>
326
327<!--=========================================================================-->
328<h2 id="icedtea">IcedTea Java Virtual Machine Implementation</h2>
329
330<div class="doc_text">
331<p>
332<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
333harness to build OpenJDK using only free software build tools and to provide
334replacements for the not-yet free parts of OpenJDK. One of the extensions that
335IcedTea provides is a new JIT compiler named <a
336href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
337to provide native code generation without introducing processor-dependent
338code.
339</p>
340
341<p> OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested
342and are known to work with LLVM 2.9 (and continue to work with older LLVM
343releases &gt;= 2.6 as well).</p>
344</div>
345
346<!--=========================================================================-->
347<h2>Glasgow Haskell Compiler (GHC)</h2>
348
349<div class="doc_text">
350<p>GHC is an open source, state-of-the-art programming suite for Haskell,
351a standard lazy functional programming language. It includes an
352optimizing static compiler generating good code for a variety of
353platforms, together with an interactive system for convenient, quick
354development.</p>
355
356<p>In addition to the existing C and native code generators, GHC 7.0 now
357supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p>
358</div>
359
360<!--=========================================================================-->
361<h2>Polly - Polyhedral optimizations for LLVM</h2>
362
363<div class="doc_text">
364<p>Polly is a project that aims to provide advanced memory access optimizations
365to better take advantage of SIMD units, cache hierarchies, multiple cores or
366even vector accelerators for LLVM. Built around an abstract mathematical
367description based on Z-polyhedra, it provides the infrastructure to develop
368advanced optimizations in LLVM and to connect complex external optimizers. In
369its first year of existence Polly already provides an exact value-based
370dependency analysis as well as basic SIMD and OpenMP code generation support.
371Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality
372and parallelism.</p>
373</div>
Chris Lattner75547712010-10-03 23:49:06 +0000374
Chris Lattnere0518442010-10-01 06:34:49 +0000375
Chris Lattner8348b472008-06-08 21:58:17 +0000376<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000377<h1>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000378 <a name="whatsnew">What's New in LLVM 2.9?</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000379</h1>
Chris Lattner8348b472008-06-08 21:58:17 +0000380<!-- *********************************************************************** -->
381
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000382<div class="doc_text">
383
Chris Lattner61358ab2009-10-13 17:48:04 +0000384<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000385minor improvements. Some of the major improvements and new features are listed
386in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000387</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000388
Chris Lattner914ce462010-04-22 06:28:20 +0000389</div>
390
391<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000392<h2>
Chris Lattner252b83d2008-02-06 18:00:06 +0000393<a name="majorfeatures">Major New Features</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000394</h2>
Chris Lattner252b83d2008-02-06 18:00:06 +0000395
396<div class="doc_text">
397
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000398<p>LLVM 2.9 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000399
400<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000401
402<li>
403 TBAA: On by default in clang. Disable it with -fno-strict-aliasing.
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000404 Could be more aggressive for structs.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000405</li>
406
407<li>New Nvidia PTX backend, not generally useful in 2.9 though.</li>
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000408
Chris Lattner1efe27e2011-04-06 00:45:11 +0000409<li>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000410Much better debug info generated, particularly in optimized code situations.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000411</li>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000412
Chris Lattner1efe27e2011-04-06 00:45:11 +0000413<li>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000414inline asm multiple alternative constraint support.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000415</li>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000416
Chris Lattner1efe27e2011-04-06 00:45:11 +0000417<li>
418 New naming rules in coding standards: CodingStandards.html#ll_naming
419</li>
Chris Lattner0f310ee2011-04-05 21:37:08 +0000420
Chris Lattner8170c102008-02-10 08:18:42 +0000421</ul>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000422
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000423</div>
424
Chris Lattner84977642007-09-21 03:54:09 +0000425<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000426<h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000427<a name="coreimprovements">LLVM IR and Core Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000428</h2>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000429
430<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000431<p>LLVM IR has several new features for better support of new targets and that
432expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000433
Chris Lattner791f77b2008-06-05 06:25:56 +0000434<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000435<li>udiv, ashr, lshr, shl now have exact and nuw/nsw bits:
436 PR8862 / LangRef.html</li>
437
438 unnamed_addr + PR8927
439
440 new 'hotpatch' attribute: LangRef.html#fnattrs
441
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000442</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000443
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000444</div>
445
446<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000447<h2>
Chris Lattneracce85d2008-02-10 07:46:44 +0000448<a name="optimizer">Optimizer Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000449</h2>
Chris Lattneracce85d2008-02-10 07:46:44 +0000450
451<div class="doc_text">
452
Chris Lattner61358ab2009-10-13 17:48:04 +0000453<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerf3013872008-10-13 21:50:36 +0000454release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000455
456<ul>
Rafael Espindolaa26f36c2011-03-18 04:07:44 +0000457 <li>LTO has been improved to use MC for parsing inline asm and now
458 can build large programs like Firefox 4 on both OS X and Linux.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000459
460
461 LoopIdiom: memset/memcpy formation and memset_pattern on darwin. Build with
462 -ffreestanding or -fno-builtin if your memcpy is being compiled into infinite
463 recursion.
464
465 TargetLibraryInfo
466
467 EarlyCSE pass.
468 LoopInstSimplify pass.
469
470New <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a> infrastructure
471 for region-based optimizations.
472
473 Can optimize printf to iprintf when no floating point is used, for embedded
474 targets with smaller iprintf implementation.
475
476Speedups to various mid-level passes:
477 GVN is much faster on functions with deep dominator trees / lots of BBs.
478 DomTree and DominatorFrontier are much faster to compute, and preserved by
479 more passes (so they are computed less often)
480 SRoA is also much faster and doesn't use DominanceFrontier.
481
482DSE is more aggressive with stores of different types: e.g. a large store
483 following a small one to the same address.
484
485
486We now optimize various idioms for overflow detection into check of the flag
487 register on various CPUs, e.g.:
488 unsigned long t = a+b;
489 if (t &lt; a) ...
490 into:
491 addq %rdi, %rbx
492 jno LBB0_2
493
494
Chris Lattner11b66112010-10-04 02:42:39 +0000495</ul>
496
497<!--
498<p>In addition to these features that are done in 2.8, there is preliminary
499 support in the release for Type Based Alias Analysis
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000500 Preliminary work on TBAA but not usable in 2.8.
501 New CorrelatedValuePropagation pass, not on by default in 2.8 yet.
Chris Lattner11b66112010-10-04 02:42:39 +0000502-->
Chris Lattner917cc712009-03-02 02:37:32 +0000503
Chris Lattner61358ab2009-10-13 17:48:04 +0000504</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000505
Chris Lattner0b832202008-06-08 02:45:07 +0000506<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000507<h2>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000508<a name="mc">MC Level Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000509</h2>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000510
511<div class="doc_text">
512<p>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000513The LLVM Machine Code (aka MC) subsystem was created to solve a number
Chris Lattner4ba2b652010-09-30 16:31:33 +0000514of problems in the realm of assembly, disassembly, object file format handling,
515and a number of other related areas that CPU instruction-set level tools work
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000516in.</p>
517
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000518<ul>
Rafael Espindolaa26f36c2011-03-18 04:07:44 +0000519 <li>MC is now used by default for ELF systems on x86 and
520 x86-64.</li>
521 <li>MC supports and CodeGen uses the <tt>.loc</tt> directives for
522 producing line number debug info. This produces more compact line
523 tables.</li>
524 <li>MC supports the <tt>.cfi_*</tt> directives for producing DWARF
525 frame information, but it is still not used by CodeGen by default.</li>
526 <li>COFF support?</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000527
528
529 MC Assembler: X86 now generates much better diagnostics for common errors,
530 is much faster at matching instructions, is much more bug-compatible with
531 the GAS assembler, and is now generally useful for a broad range of X86
532 assembly.
533
534
535 ELF MC support: on by default in clang. There are still known missing features
536 for human written assembly.
537
538
539 Some basic <a href="CodeGenerator.html#mc">internals documentation</a> for MC.
540
541 MC Assembler support for .file and .loc.
542
543 tblgen support for assembler aliases: <a
544 href="CodeGenerator.html#na_instparsing">MnemonicAlias and InstAlias</a>
545
546 Win32 PE-COFF support in the MC assembler has made a lot of progress in the 2.9
547 timeframe, but is still not generally useful. Please see
548 "http://llvm.org/bugs/showdependencytree.cgi?id=9100&amp;hide_resolved=1" for open bugs?
549
550
551 lib/Object and llvm-objdump
552 Experimental format independent object file manipulation library.
553 * Supports PE/COFF and ELF.
554 * llvm-nm extended to work with object files. Exactly matches
555 binutils-nm for the files I've tested.
556 * llvm-objdump added with support for disassembly (no relocations displayed).
557
558
559
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000560</ul>
561
562<p>For more information, please see the <a
Chris Lattner4ba2b652010-09-30 16:31:33 +0000563href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
564LLVM MC Project Blog Post</a>.
565</p>
566
NAKAMURA Takumi45c435a2011-04-05 08:24:22 +0000567</div>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000568
Chris Lattner4ba2b652010-09-30 16:31:33 +0000569<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000570<h2>
Chris Lattner511433e2009-03-02 03:24:11 +0000571<a name="codegen">Target Independent Code Generator Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000572</h2>
Chris Lattner0b832202008-06-08 02:45:07 +0000573
574<div class="doc_text">
575
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000576<p>We have put a significant amount of work into the code generator
577infrastructure, which allows us to implement more aggressive algorithms and make
578it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000579
580<ul>
Chris Lattner3bdcda12010-10-04 03:58:12 +0000581<!-- SplitKit -->
Chris Lattner1efe27e2011-04-06 00:45:11 +0000582
583<li>The pre-register-allocation (preRA) instruction scheduler models register
584 pressure much more accurately in some cases. This allows the adoption of more
585 aggressive scheduling heuristics.
586</li>
587
588 LiveDebugVariables is a new pass that keeps track of debugging information for
589 user variables that are kept in registers in optimized builds.
590
591
592Scheduler now models operand latency and pipeline forwarding.
593
594Major regalloc rewrite, not on by default for 2.9 and not advised to use it.
595 * New basic register allocator that can be used as a safe fallback when
596 debugging. Enable with -regalloc=basic.
597 * New infrastructure for live range splitting. SplitKit can break a live
598 interval into smaller pieces while preserving SSA form, and SpillPlacement
599 can help find the best split points. This is a work in progress so the API
600 is changing quickly.
601 * The inline spiller has learned to clean up after live range splitting. It
602 can hoist spills out of loops, and it can eliminate redundant spills.
603 Rematerialization works with live range splitting.
604 * New greedy register allocator using live range splitting. This will be the
605 default register allocator in the next LLVM release, but it is not turned on
606 by default in 2.9.
607
608
609
Chris Lattner84977642007-09-21 03:54:09 +0000610</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000611</div>
612
Chris Lattner917cc712009-03-02 02:37:32 +0000613<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000614<h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000615<a name="x86">X86-32 and X86-64 Target Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000616</h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000617
618<div class="doc_text">
Chris Lattner7714c912010-10-04 04:39:25 +0000619<p>New features and major changes in the X86 target include:
Chris Lattner917cc712009-03-02 02:37:32 +0000620</p>
621
622<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000623<li>
624X86: Reimplemented all of MMX to introduce a new LLVM IR x86_mmx type. Now
625 random types like &lt;2 x i32&gt; are not iseld to mmx without emms. The
626 -disable-mmx flag is gone now.
627</li>
628
629 <li>
630X86 support for FS/GS relative loads and stores using address space 256/257 are
631 reliable now.
632 </li>
633
634 <li>
635X86: Much better codegen for several cases using adc/sbb instead of cmovs for
636 conditional increment and other idioms.
637 </li>
638
639 <li>
640 The X86 backend has adopted a new preRA scheduling
641 mode, "list-ilp", to shorten the height of instruction schedules
642 without inducing register spills.
643 </li>
644
645 MC assembler support for 3dNow! and 3DNowA instructions.
646
NAKAMURA Takumi45c435a2011-04-05 08:24:22 +0000647 <li>Several bugs have been fixed for Windows x64 code generator.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000648</ul>
649
Chris Lattner917cc712009-03-02 02:37:32 +0000650</div>
Chris Lattner84977642007-09-21 03:54:09 +0000651
652<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000653<h2>
Chris Lattner61358ab2009-10-13 17:48:04 +0000654<a name="ARM">ARM Target Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000655</h2>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000656
657<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000658<p>New features of the ARM target include:
659</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000660
661<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000662<li>ARM Fast ISel</li>
663<li>ARM: New code placement pass.</li>
664<li>ARM: Improved code generation for Cortex-A8 and Cortex-A9 CPUs.</li>
665<li>ARM: __builtin_prefetch turns into prefetch instructions.</li>
666<li>Countless ARM microoptimizations.</li>
667
668<li> The ARM backend preRA scheduler now models machine resources at cycle
669 granularity. This allows the scheduler to both accurately model
670 instruction latency and avoid overcommitting functional units.</li>
671
672
Bob Wilsone8472772010-09-13 17:39:35 +0000673</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000674</div>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000675
676<!--=========================================================================-->
677<h2>
678<a name="OtherTS">Other Target Specific Improvements</a>
679</h2>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000680
Chris Lattner1efe27e2011-04-06 00:45:11 +0000681<div class="doc_text">
682<ul>
683 PPC: Switched to MCInstPrinter, and MCCodeEmitter. Ready to implement support
684 for directly writing out mach-o object files, but noone seems interested.
685
686 MicroBlaze: major updates for aggressive delay slot filler, MC-based assembly
687 printing, assembly instruction parsing, ELF .o file emission, and MC
688 instruction disassembler.
689
690 SPARC: Many improvements, including using the Y registers for multiplications
691 and addition of a simple delay slot filler.
692
693</ul>
694</div>
Chris Lattner77d29b12008-06-05 08:02:49 +0000695
696<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000697<h2>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000698<a name="changes">Major Changes and Removed Features</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000699</h2>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000700
701<div class="doc_text">
702
Chris Lattnereeb4da02008-10-13 22:06:31 +0000703<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000704on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000705from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000706
707<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000708 last release for llvm-gcc
709
710- DIBuilder provides simpler interface for front ends like Clang to encode debug info in LLVM IR.
711 - This interface hides implementation details (e.g. DIDerivedType, existence of compile unit etc..) that any front end should not know about.
712 For example, DIFactory DebugFactory;
713 Ty = DebugFactory.CreateDerivedType(DW_TAG_volatile_type,
714 findRegion(TYPE_CONTEXT(type)),
715 StringRef(),
716 getOrCreateFile(main_input_filename),
717 0 /*line no*/,
718 NodeSizeInBits(type),
719 NodeAlignInBits(type),
720 0 /*offset */,
721 0 /* flags */,
722 MainTy);
723 can be replaced by
724 DbgTy = DBuilder.createQualifiedType(DW_TAG_volatile_type, MainTy);
725DIFactory is gone now.
726
727
Chris Lattnereeb4da02008-10-13 22:06:31 +0000728
Chris Lattnerbb117712010-10-04 01:29:06 +0000729
730
Chris Lattner1efe27e2011-04-06 00:45:11 +0000731
732 LoopIndexSplit pass was removed, unmaintained.
733 LiveValues, SimplifyHalfPowrLibCalls, and GEPSplitter were removed.
734 Removed the PartialSpecialization pass, it was unmaintained and buggy.
735
736 DIFactory removed, use DIBuilder instead.
737
738 Triple::normalize is new, llvm triples are always stored in normalized form internally.
739
740 Triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32 instead.
741
742 PointerTracking has been removed from mainline, moved to ClamAV.
743
Devang Patelb34dd132008-10-14 20:03:43 +0000744</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000745
Chris Lattnerf6662f92008-10-13 17:57:36 +0000746</div>
747
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000748<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000749<h2>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000750<a name="api_changes">Internal API Changes</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000751</h2>
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000752
753<div class="doc_text">
754
Chris Lattner1efe27e2011-04-06 00:45:11 +0000755<p>In addition, many APIs have changed in this release. Some of the major
756 LLVM API changes are:</p>
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000757
758<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000759
760 include/llvm/System merged into include/llvm/Support.
761
762
763 APInt API changes, see PR5207.
764
765 MVT::Flag renamed to MVT::Glue
766
767
768 error_code + libsystem + PathV2 changes
769 The system_error header from C++0x was added.
770 * Use if (error_code ec = function()) to check for error conditions
771 from functions which return it.
772 * error_code::message returns a human readable description of the error.
773
774 PathV1 has been deprecated in favor of PathV2 (sorry I didn't finish
775 this before the release).
776 * No Path class, use a r-value convertible to a twine instead.
777 * Assumes all paths are UTF-8.
778
779
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000780</ul>
781</div>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000782
Chris Lattner79c3fe12003-10-02 04:57:28 +0000783<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000784<h1>
Misha Brukman500bc302003-11-22 00:38:41 +0000785 <a name="knownproblems">Known Problems</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000786</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000787<!-- *********************************************************************** -->
788
Misha Brukman500bc302003-11-22 00:38:41 +0000789<div class="doc_text">
790
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000791<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000792listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000793href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000794there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000795
Misha Brukman500bc302003-11-22 00:38:41 +0000796</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000797
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000798<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000799<h2>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000800 <a name="experimental">Experimental features included with this release</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000801</h2>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000802
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000803<div class="doc_text">
804
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000805<p>The following components of this LLVM release are either untested, known to
806be broken or unreliable, or are in early development. These components should
807not be relied on, and bugs should not be filed against them, but they may be
808useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000809components, please contact us on the <a
810href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000811
812<ul>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000813<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ
Chris Lattnerbb117712010-10-04 01:29:06 +0000814 and XCore backends are experimental.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000815<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000816 other than darwin-i386 and darwin-x86_64. FIXME: Not true on ELF anymore?</li>
817
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000818</ul>
819
820</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000821
Misha Brukman500bc302003-11-22 00:38:41 +0000822<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000823<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000824 <a name="x86-be">Known problems with the X86 back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000825</h2>
John Criswellc0c186d2005-11-08 21:11:33 +0000826
827<div class="doc_text">
828
829<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000830 <li>The X86 backend does not yet support
831 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
832 floating point stack</a>. It supports the 'f' and 't' constraints, but not
833 'u'.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000834 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000835 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000836 argument constructs on X86-64 by lowering them manually.</li>
NAKAMURA Takumi45c435a2011-04-05 08:24:22 +0000837 <li>Windows x64 (aka Win64) code generator has a few issues.
838 <ul>
839 <li>llvm-gcc cannot build the mingw-w64 runtime currently
840 due to lack of support for the 'u' inline assembly
841 constraint and for X87 floating point inline assembly.</li>
842 <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt>
843 due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
844 It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
845 <li>Miss-aligned MOVDQA might crash your program. It is due to
846 <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>,
847 lack of handling aligned internal globals.</li>
848 </ul>
849 </li>
850
Chris Lattner26299222006-11-18 07:51:14 +0000851</ul>
852
853</div>
854
855<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000856<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000857 <a name="ppc-be">Known problems with the PowerPC back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000858</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000859
860<div class="doc_text">
861
862<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000863<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000864compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000865</ul>
866
867</div>
868
869<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000870<h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000871 <a name="arm-be">Known problems with the ARM back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000872</h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000873
874<div class="doc_text">
875
876<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000877<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000878processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000879results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000880<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000881</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000882</ul>
883
884</div>
885
886<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000887<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000888 <a name="sparc-be">Known problems with the SPARC back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000889</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000890
891<div class="doc_text">
892
893<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000894<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattner26299222006-11-18 07:51:14 +0000895 support the 64-bit SPARC ABI (-m64).</li>
896</ul>
897
898</div>
899
900<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000901<h2>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000902 <a name="mips-be">Known problems with the MIPS back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000903</h2>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000904
905<div class="doc_text">
906
907<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000908<li>64-bit MIPS targets are not supported yet.</li>
909</ul>
910
911</div>
912
913<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000914<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000915 <a name="alpha-be">Known problems with the Alpha back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000916</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000917
918<div class="doc_text">
919
920<ul>
921
922<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
923appropriate nops inserted to ensure restartability.</li>
924
John Criswellc0c186d2005-11-08 21:11:33 +0000925</ul>
926</div>
927
Chris Lattner26299222006-11-18 07:51:14 +0000928<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000929<h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000930 <a name="c-be">Known problems with the C back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000931</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000932
933<div class="doc_text">
934
Chris Lattner3016ee92010-09-29 05:34:42 +0000935<p>The C backend has numerous problems and is not being actively maintained.
936Depending on it for anything serious is not advised.</p>
937
Chris Lattner26299222006-11-18 07:51:14 +0000938<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000939<li><a href="http://llvm.org/PR802">The C backend has only basic support for
940 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000941<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
942 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000943 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000944<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000945<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000946</ul>
947
948</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000949
Misha Brukman500bc302003-11-22 00:38:41 +0000950
951<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000952<h2>
Chris Lattner3016ee92010-09-29 05:34:42 +0000953 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000954</h2>
Chris Lattner47588f92003-10-02 05:07:23 +0000955
Misha Brukman500bc302003-11-22 00:38:41 +0000956<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000957
Chris Lattner3016ee92010-09-29 05:34:42 +0000958<p>llvm-gcc is generally very stable for the C family of languages. The only
959 major language feature of GCC not supported by llvm-gcc is the
960 <tt>__builtin_apply</tt> family of builtins. However, some extensions
961 are only supported on some targets. For example, trampolines are only
962 supported on some targets (these are used when you take the address of a
963 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000964
Chris Lattner3016ee92010-09-29 05:34:42 +0000965<p>Fortran support generally works, but there are still several unresolved bugs
966 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
967 tools/gfortran component for details. Note that llvm-gcc is missing major
968 Fortran performance work in the frontend and library that went into GCC after
969 4.2. If you are interested in Fortran, we recommend that you consider using
970 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000971
Duncan Sands3af96332010-10-04 10:06:56 +0000972<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
973actively maintained. If you are interested in Ada, we recommend that you
974consider using <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000975</div>
976
Chris Lattner79c3fe12003-10-02 04:57:28 +0000977<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000978<h1>
Misha Brukman500bc302003-11-22 00:38:41 +0000979 <a name="additionalinfo">Additional Information</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000980</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000981<!-- *********************************************************************** -->
982
Misha Brukman500bc302003-11-22 00:38:41 +0000983<div class="doc_text">
984
Chris Lattner416db102005-05-16 17:13:10 +0000985<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000986href="http://llvm.org">LLVM web page</a>, in particular in the <a
987href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000988contains versions of the API documentation which is up-to-date with the
989Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000990You can access versions of these documents specific to this release by going
991into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000992
Misha Brukman500bc302003-11-22 00:38:41 +0000993<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000994us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000995lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000996
Misha Brukman500bc302003-11-22 00:38:41 +0000997</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000998
999<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +00001000
Misha Brukman500bc302003-11-22 00:38:41 +00001001<hr>
Misha Brukman2061e892003-11-22 01:23:39 +00001002<address>
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Chris Lattnerb4b0ce72007-05-18 00:44:29 +00001008 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +00001009 Last modified: $Date$
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