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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 Lattner49123fd2011-04-06 06:29:50 +000031<!--
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000032<h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.9
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000033release.<br>
34You may prefer the
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000035<a href="http://llvm.org/releases/2.8/docs/ReleaseNotes.html">LLVM 2.8
Dan Gohmanb44f6c62010-05-03 23:51:05 +000036Release Notes</a>.</h1>
Chris Lattner49123fd2011-04-06 06:29:50 +000037 -->
Jeffrey Yasskinbec48772010-01-28 01:14:43 +000038
Chris Lattner79c3fe12003-10-02 04:57:28 +000039<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000040<h1>
Misha Brukman500bc302003-11-22 00:38:41 +000041 <a name="intro">Introduction</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000042</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +000043<!-- *********************************************************************** -->
44
Misha Brukman500bc302003-11-22 00:38:41 +000045<div class="doc_text">
46
Chris Lattnerf6662f92008-10-13 17:57:36 +000047<p>This document contains the release notes for the LLVM Compiler
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000048Infrastructure, release 2.9. Here we describe the status of LLVM, including
Chris Lattnerf6662f92008-10-13 17:57:36 +000049major improvements from the previous release and significant known problems.
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +000050All LLVM releases may be downloaded from the <a
Chris Lattnerf6662f92008-10-13 17:57:36 +000051href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +000052
Chris Lattner7506b1d2004-12-07 08:04:13 +000053<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +000054release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +000055web site</a>. If you have questions or comments, the <a
Chris Lattnerc66bfef2010-03-17 04:41:49 +000056href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
57Mailing List</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +000058
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +000059<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +000060main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greiffa933f82008-10-14 11:00:32 +000061current one. To see the release notes for a specific release, please see the
Chris Lattner84977642007-09-21 03:54:09 +000062<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +000063
64</div>
Chris Lattner61358ab2009-10-13 17:48:04 +000065
Chris Lattnere4dc1962011-04-05 23:22:33 +000066<!-- Features that need text if they're finished for 3.1:
67 ARM EHABI
Chris Lattner914ce462010-04-22 06:28:20 +000068 combiner-aa?
Chris Lattner61358ab2009-10-13 17:48:04 +000069 strong phi elim
Chris Lattner61358ab2009-10-13 17:48:04 +000070 loop dependence analysis
Chris Lattnere07043c2010-09-29 05:30:03 +000071 CorrelatedValuePropagation
Chris Lattnere4dc1962011-04-05 23:22:33 +000072 lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
Chris Lattneracce85d2008-02-10 07:46:44 +000073 -->
Chris Lattnere07043c2010-09-29 05:30:03 +000074
Chris Lattner96a445e2008-10-13 18:01:01 +000075<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000076<h1>
Chris Lattner96a445e2008-10-13 18:01:01 +000077 <a name="subproj">Sub-project Status Update</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000078</h1>
Chris Lattner96a445e2008-10-13 18:01:01 +000079<!-- *********************************************************************** -->
Chris Lattnerea34f642008-06-08 21:34:41 +000080
81<div class="doc_text">
Chris Lattner8348b472008-06-08 21:58:17 +000082<p>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +000083The LLVM 2.9 distribution currently consists of code from the core LLVM
Chris Lattner61358ab2009-10-13 17:48:04 +000084repository (which roughly includes the LLVM optimizers, code generators
85and supporting tools), the Clang repository and the llvm-gcc repository. In
86addition to this code, the LLVM Project includes other sub-projects that are in
87development. Here we include updates on these subprojects.
Bill Wendling63d8c552009-03-02 04:28:57 +000088</p>
Chris Lattner96a445e2008-10-13 18:01:01 +000089
Chris Lattner8348b472008-06-08 21:58:17 +000090</div>
91
Chris Lattner96a445e2008-10-13 18:01:01 +000092
Chris Lattner8348b472008-06-08 21:58:17 +000093<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +000094<h2>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +000095<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +000096</h2>
Chris Lattner8348b472008-06-08 21:58:17 +000097
98<div class="doc_text">
99
Chris Lattner095539f2010-04-26 17:42:18 +0000100<p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
101C++, and Objective-C languages. Clang aims to provide a better user experience
102through expressive diagnostics, a high level of conformance to language
103standards, fast compilation, and low memory use. Like LLVM, Clang provides a
104modular, library-based architecture that makes it suitable for creating or
105integrating with other development tools. Clang is considered a
Chris Lattnere07043c2010-09-29 05:30:03 +0000106production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
Chris Lattner1efe27e2011-04-06 00:45:11 +0000107(32- and 64-bit), and for darwin/arm targets.</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000108
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000109<p>In the LLVM 2.9 time-frame, the Clang team has made many improvements in C,
110C++ and Objective-C support. C++ support is now generally rock solid, has
Chris Lattnerdf448a32011-04-06 00:56:12 +0000111been exercised on a broad variety of code, and has several new <a
112href="http://clang.llvm.org/cxx_status.html#cxx0x">C++'0x features</a>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000113implemented (such as rvalue references and variadic templates). LLVM 2.9 has
114also brought in a large range of bug fixes and minor features (e.g. __label__
115support), and is much more compatible with the Linux Kernel.</p>
116
Duncan Sandsf3ba7af2011-04-06 08:07:40 +0000117<p>If Clang rejects your code but another compiler accepts it, please take a
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000118look at the <a href="http://clang.llvm.org/compatibility.html">language
Duncan Sandsf3ba7af2011-04-06 08:07:40 +0000119compatibility</a> guide to make sure this is not intentional or a known issue.
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000120</p>
Bill Wendling741748a2008-10-27 09:27:33 +0000121
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000122<ul>
123</ul>
Chris Lattnerfb97b2d2008-10-13 18:11:54 +0000124</div>
125
126<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000127<h2>
Duncan Sands528a5102011-04-04 11:09:08 +0000128<a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000129</h2>
Chris Lattner61358ab2009-10-13 17:48:04 +0000130
131<div class="doc_text">
132<p>
Duncan Sands528a5102011-04-04 11:09:08 +0000133<a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
134<a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
135optimizers and code generators with LLVM's.
136Currently it requires a patched version of gcc-4.5.
137The plugin can target the x86-32 and x86-64 processor families and has been
138used successfully on the Darwin, FreeBSD and Linux platforms.
139The Ada, C, C++ and Fortran languages work well.
140The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is
141not known whether the compiled code actually works or not!
Duncan Sands749fd832010-04-02 09:23:15 +0000142</p>
143
144<p>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000145The 2.9 release has the following notable changes:
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000146<ul>
Duncan Sands528a5102011-04-04 11:09:08 +0000147<li>The plugin is much more stable when compiling Fortran.</li>
Chris Lattnerdf448a32011-04-06 00:56:12 +0000148<li>Inline assembly where an asm output is tied to an input of a different size
149is now supported in many more cases.</li>
Duncan Sands528a5102011-04-04 11:09:08 +0000150<li>Basic support for the __float128 type was added. It is now possible to
151generate LLVM IR from programs using __float128 but code generation does not
152work yet.</li>
153<li>Compiling Java programs no longer systematically crashes the plugin.</li>
Duncan Sands4b1da2b2010-09-30 17:37:34 +0000154</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000155
156</div>
157
Chris Lattner75547712010-10-03 23:49:06 +0000158<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000159<h2>
Chris Lattner75547712010-10-03 23:49:06 +0000160<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000161</h2>
Chris Lattner75547712010-10-03 23:49:06 +0000162
163<div class="doc_text">
164<p>
165The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
166is a simple library that provides an implementation of the low-level
167target-specific hooks required by code generation and other runtime components.
168For example, when compiling for a 32-bit target, converting a double to a 64-bit
169unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
170function. The compiler-rt library provides highly optimized implementations of
171this and other low-level routines (some are 3x faster than the equivalent
172libgcc routines).</p>
173
Chris Lattnerdf448a32011-04-06 00:56:12 +0000174<p>In the LLVM 2.9 timeframe, compiler_rt has had several minor changes for
175 better ARM support, and a fairly major license change. All of the code in the
176 compiler-rt project is now <a href="DeveloperPolicy.html#license">dual
177 licensed</a> under MIT and UIUC license, which allows you to use compiler-rt
178 in applications without the binary copyright reproduction clause. If you
179 prefer the LLVM/UIUC license, you are free to continue using it under that
180 license as well.</p>
Chris Lattner75547712010-10-03 23:49:06 +0000181
182</div>
Chris Lattner61358ab2009-10-13 17:48:04 +0000183
184<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000185<h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000186<a name="lldb">LLDB: Low Level Debugger</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000187</h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000188
189<div class="doc_text">
190<p>
Chris Lattner75547712010-10-03 23:49:06 +0000191<a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
192umbrella of projects. LLDB is a next generation, high-performance debugger. It
193is built as a set of reusable components which highly leverage existing
194libraries in the larger LLVM Project, such as the Clang expression parser, the
195LLVM disassembler and the LLVM JIT.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000196
197<p>
Chris Lattnerdf448a32011-04-06 00:56:12 +0000198LLDB is has advanced by leaps and bounds in the 2.9 timeframe. It is
199dramatically more stable and useful, and includes both a new <a
200href="http://lldb.llvm.org/tutorial.html">tutorial</a> and a <a
201href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with
202GDB</a>.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000203
204</div>
205
206<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000207<h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000208<a name="libc++">libc++: C++ Standard Library</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000209</h2>
Chris Lattnere07043c2010-09-29 05:30:03 +0000210
211<div class="doc_text">
212<p>
Tobias Grossercdce44b2010-10-06 21:07:30 +0000213<a href="http://libcxx.llvm.org/">libc++</a> is another new member of the LLVM
Chris Lattner75547712010-10-03 23:49:06 +0000214family. It is an implementation of the C++ standard library, written from the
215ground up to specifically target the forthcoming C++'0X standard and focus on
216delivering great performance.</p>
Chris Lattnere07043c2010-09-29 05:30:03 +0000217
218<p>
Chris Lattner2009c492011-04-06 00:59:18 +0000219In the LLVM 2.9 timeframe, libc++ has had numerous bugs fixed, and is now being
220co-developed with Clang's C++'0x mode.</p>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000221
Chris Lattner2009c492011-04-06 00:59:18 +0000222<p>
223Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
224 licensed</a> under the MIT and UIUC license, allowing it to be used more
225 permissively.
Chris Lattnere07043c2010-09-29 05:30:03 +0000226</p>
227
228</div>
229
Chris Lattner61358ab2009-10-13 17:48:04 +0000230
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000231
232<!--=========================================================================-->
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000233<!--
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000234<h2>
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000235<a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000236</h2>
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000237
238<div class="doc_text">
239<p>
240<a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
241programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
242through the application and records state transitions that lead to fault
243states. This allows it to construct testcases that lead to faults and can even
244be used to verify some algorithms.
245</p>
246
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000247<p>UPDATE!</p>
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000248</div>-->
Daniel Dunbar97b01a82010-10-04 17:39:47 +0000249
250
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000251<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000252<h1>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000253 <a name="externalproj">External Open Source Projects Using LLVM 2.9</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000254</h1>
Chris Lattnerab68e9e2009-02-26 22:33:38 +0000255<!-- *********************************************************************** -->
256
Chris Lattner61358ab2009-10-13 17:48:04 +0000257<div class="doc_text">
258
259<p>An exciting aspect of LLVM is that it is used as an enabling technology for
260 a lot of other language and tools projects. This section lists some of the
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000261 projects that have already been updated to work with LLVM 2.9.</p>
Chris Lattner7c8e7962010-04-26 17:38:10 +0000262</div>
263
Chris Lattner75547712010-10-03 23:49:06 +0000264
Chris Lattner3bfe57e2011-04-06 01:13:49 +0000265<!--=========================================================================-->
266<h2>Crack Programming Language</h2>
267
268<div class="doc_text">
269<p>
270<a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide the
271ease of development of a scripting language with the performance of a compiled
272language. The language derives concepts from C++, Java and Python, incorporating
273object-oriented programming, operator overloading and strong typing.</p>
274</div>
275
276
277<!--=========================================================================-->
278<h2>TTA-based Codesign Environment (TCE)</h2>
279
280<div class="doc_text">
281<p>TCE is a toolset for designing application-specific processors (ASP) based on
282the Transport triggered architecture (TTA). The toolset provides a complete
283co-design flow from C/C++ programs down to synthesizable VHDL and parallel
284program binaries. Processor customization points include the register files,
285function units, supported operations, and the interconnection network.</p>
286
287<p>TCE uses Clang and LLVM for C/C++ language support, target independent
288optimizations and also for parts of code generation. It generates new LLVM-based
289code generators "on the fly" for the designed TTA processors and loads them in
290to the compiler backend as runtime libraries to avoid per-target recompilation
291of larger parts of the compiler chain.</p>
292</div>
293
294
295
296<!--=========================================================================-->
297<h2>PinaVM</h2>
298
299<div class="doc_text">
300<p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open
301source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many
302other front-ends, PinaVM actually executes the elaboration of the
303program analyzed using LLVM's JIT infrastructure. It later enriches the
304bitcode with SystemC-specific information.</p>
305</div>
306
307<!--=========================================================================-->
308<h2>Pure</h2>
309
310<div class="doc_text">
311<p><a href="http://pure-lang.googlecode.com/">Pure</a> is an
312 algebraic/functional
313 programming language based on term rewriting. Programs are collections
314 of equations which are used to evaluate expressions in a symbolic
315 fashion. The interpreter uses LLVM as a backend to JIT-compile Pure
316 programs to fast native code. Pure offers dynamic typing, eager and lazy
317 evaluation, lexical closures, a hygienic macro system (also based on
318 term rewriting), built-in list and matrix support (including list and
319 matrix comprehensions) and an easy-to-use interface to C and other
320 programming languages (including the ability to load LLVM bitcode
321 modules, and inline C, C++, Fortran and Faust code in Pure programs if
322 the corresponding LLVM-enabled compilers are installed).</p>
323
324<p>Pure version 0.47 has been tested and is known to work with LLVM 2.9
325 (and continues to work with older LLVM releases &gt;= 2.5).</p>
326</div>
327
328<!--=========================================================================-->
329<h2 id="icedtea">IcedTea Java Virtual Machine Implementation</h2>
330
331<div class="doc_text">
332<p>
333<a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
334harness to build OpenJDK using only free software build tools and to provide
335replacements for the not-yet free parts of OpenJDK. One of the extensions that
336IcedTea provides is a new JIT compiler named <a
337href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
338to provide native code generation without introducing processor-dependent
339code.
340</p>
341
342<p> OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested
343and are known to work with LLVM 2.9 (and continue to work with older LLVM
344releases &gt;= 2.6 as well).</p>
345</div>
346
347<!--=========================================================================-->
348<h2>Glasgow Haskell Compiler (GHC)</h2>
349
350<div class="doc_text">
351<p>GHC is an open source, state-of-the-art programming suite for Haskell,
352a standard lazy functional programming language. It includes an
353optimizing static compiler generating good code for a variety of
354platforms, together with an interactive system for convenient, quick
355development.</p>
356
357<p>In addition to the existing C and native code generators, GHC 7.0 now
358supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p>
359</div>
360
361<!--=========================================================================-->
362<h2>Polly - Polyhedral optimizations for LLVM</h2>
363
364<div class="doc_text">
365<p>Polly is a project that aims to provide advanced memory access optimizations
366to better take advantage of SIMD units, cache hierarchies, multiple cores or
367even vector accelerators for LLVM. Built around an abstract mathematical
368description based on Z-polyhedra, it provides the infrastructure to develop
369advanced optimizations in LLVM and to connect complex external optimizers. In
370its first year of existence Polly already provides an exact value-based
371dependency analysis as well as basic SIMD and OpenMP code generation support.
372Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality
373and parallelism.</p>
374</div>
Chris Lattner75547712010-10-03 23:49:06 +0000375
Chris Lattnere0518442010-10-01 06:34:49 +0000376
Chris Lattner8348b472008-06-08 21:58:17 +0000377<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000378<h1>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000379 <a name="whatsnew">What's New in LLVM 2.9?</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000380</h1>
Chris Lattner8348b472008-06-08 21:58:17 +0000381<!-- *********************************************************************** -->
382
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000383<div class="doc_text">
384
Chris Lattner61358ab2009-10-13 17:48:04 +0000385<p>This release includes a huge number of bug fixes, performance tweaks and
Chris Lattnerf6662f92008-10-13 17:57:36 +0000386minor improvements. Some of the major improvements and new features are listed
387in this section.
Chris Lattnerf8e0b4e2008-06-08 22:59:35 +0000388</p>
Chris Lattner61358ab2009-10-13 17:48:04 +0000389
Chris Lattner914ce462010-04-22 06:28:20 +0000390</div>
391
392<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000393<h2>
Chris Lattner252b83d2008-02-06 18:00:06 +0000394<a name="majorfeatures">Major New Features</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000395</h2>
Chris Lattner252b83d2008-02-06 18:00:06 +0000396
397<div class="doc_text">
398
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000399<p>LLVM 2.9 includes several major new capabilities:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000400
401<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000402
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000403<li>Type Based Alias Analysis (TBAA) is now implemented and turned on by default
404 in Clang. This allows substantially better load/store optimization in some
405 cases. TBAA can be disabled by passing -fno-strict-aliasing.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000406</li>
407
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000408<li>This release has seen a continued focus on quality of debug information.
409 LLVM now generates much higher fidelity debug information, particularly when
410 debugging optimized code.</li>
411
412<li>Inline assembly now supports multiple alternative constraints.</li>
413
414<li>A new backend for the NVIDIA PTX virtual ISA (used to target its GPUs) is
415 under rapid development. It is not generally useful in 2.9, but is making
416 rapid progress.</li>
Chris Lattner7a8e6c52011-04-05 18:38:45 +0000417
Chris Lattner8170c102008-02-10 08:18:42 +0000418</ul>
Chris Lattner0a6f6d52011-04-05 07:19:28 +0000419
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000420</div>
421
Chris Lattner84977642007-09-21 03:54:09 +0000422<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000423<h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000424<a name="coreimprovements">LLVM IR and Core Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000425</h2>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000426
427<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000428<p>LLVM IR has several new features for better support of new targets and that
429expose new optimization opportunities:</p>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000430
Chris Lattner791f77b2008-06-05 06:25:56 +0000431<ul>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000432<li>The <a href="LangRef.html#bitwiseops">udiv, ashr, lshr, and shl</a>
433 instructions now have support exact and nuw/nsw bits to indicate that they
434 don't overflow or shift out bits. This is useful for optimization of <a
435 href="http://llvm.org/PR8862">pointer differences</a> and other cases.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000436
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000437<li>LLVM IR now supports the <a href="LangRef.html#globalvars">unnamed_addr</a>
438 attribute to indicate that constant global variables with identical
439 initializers can be merged. This fixed <a href="http://llvm.org/PR8927">an
440 issue</a> where LLVM would incorrectly merge two globals which were supposed
441 to have distinct addresses.</li>
442
443<li>The new <a href="LangRef.html#fnattrs">hotpatch attribute</a> has been added
444 to allow runtime patching of functions.</li>
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000445</ul>
Mikhail Glushenkovea65d7d2008-10-13 02:08:34 +0000446
Chris Lattnerf304ffc2008-02-10 08:17:19 +0000447</div>
448
449<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000450<h2>
Chris Lattneracce85d2008-02-10 07:46:44 +0000451<a name="optimizer">Optimizer Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000452</h2>
Chris Lattneracce85d2008-02-10 07:46:44 +0000453
454<div class="doc_text">
455
Chris Lattner61358ab2009-10-13 17:48:04 +0000456<p>In addition to a large array of minor performance tweaks and bug fixes, this
Chris Lattnerf3013872008-10-13 21:50:36 +0000457release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattneracce85d2008-02-10 07:46:44 +0000458
459<ul>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000460<li>Link Time Optimization (LTO) has been improved to use MC for parsing inline
461 assembly and now can build large programs like Firefox 4 on both Mac OS X and
462 Linux.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000463
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000464<li>The new -loop-idiom pass recognizes memset/memcpy loops (and memset_pattern
465 on darwin), turning them into library calls, which are typically better
466 optimized than inline code. If you are building a libc and notice that your
467 memcpy and memset functions are compiled into infinite recursion, please build
468 with -ffreestanding or -fno-builtin to disable this pass.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000469
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000470<li>A new -early-cse pass does a fast pass over functions to fold constants,
471 simplify expressions, perform simple dead store elimination, and perform
472 common subexpression elimination. It does a good job at catching some of the
473 trivial redundancies that exist in unoptimized code, making later passes more
474 effective.<,/li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000475
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000476<li>A new -loop-instsimplify pass is used to clean up loop bodies in the loop
477 optimizer.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000478
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000479<li>The new TargetLibraryInfo interface allows mid-level optimizations to know
480 whether the current target's runtime library has certain functions. For
481 example, the optimizer can now transform integer-only printf calls to call
482 iprintf, allowing reduced code size for embedded C libraries (e.g. newlib).
483</li>
484
485<li>LLVM has a new <a href="WritingAnLLVMPass.html#RegionPass">RegionPass</a>
486 infrastructure for region-based optimizations.</li>
487
488<li>Several optimizer passes have been substantially sped up:
489 GVN is much faster on functions with deep dominator trees and lots of basic
490 blocks. The dominator tree and dominance frontier passes are much faster to
491 compute, and preserved by more passes (so they are computed less often). The
492 -scalar-repl pass is also much faster and doesn't use DominanceFrontier.
493</li>
494
495<li>The Dead Store Elimination pass is more aggressive optimizing stores of
496 different types: e.g. a large store following a small one to the same address.
497 The MemCpyOptimizer pass handles several new forms of memcpy elimination.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000498
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000499<li>LLVM now optimizes various idioms for overflow detection into check of the
500 flag register on various CPUs. For example, we now compile:
Chris Lattner1efe27e2011-04-06 00:45:11 +0000501
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000502 <pre>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000503 unsigned long t = a+b;
504 if (t &lt; a) ...
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000505 </pre>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000506 into:
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000507 <pre>
508 addq %rdi, %rbx
509 jno LBB0_2
510 </pre>
511</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000512
Chris Lattner11b66112010-10-04 02:42:39 +0000513</ul>
514
Chris Lattner61358ab2009-10-13 17:48:04 +0000515</div>
Chris Lattner917cc712009-03-02 02:37:32 +0000516
Chris Lattner0b832202008-06-08 02:45:07 +0000517<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000518<h2>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000519<a name="mc">MC Level Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000520</h2>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000521
522<div class="doc_text">
523<p>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000524The LLVM Machine Code (aka MC) subsystem was created to solve a number
Chris Lattner4ba2b652010-09-30 16:31:33 +0000525of problems in the realm of assembly, disassembly, object file format handling,
526and a number of other related areas that CPU instruction-set level tools work
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000527in.</p>
528
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000529<ul>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000530<li>ELF MC support has matured enough for the integrated assembler to be turned
531 on by default in Clang on X86-32 and X86-64 ELF systems.</li>
532
533<li>MC supports and CodeGen uses the <tt>.file</tt> and <tt>.loc</tt> directives
534 for producing line number debug info. This produces more compact line
535 tables and easier to read .s files.</li>
536
537<li>MC supports the <tt>.cfi_*</tt> directives for producing DWARF
Rafael Espindolaa26f36c2011-03-18 04:07:44 +0000538 frame information, but it is still not used by CodeGen by default.</li>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000539
Chris Lattner1efe27e2011-04-06 00:45:11 +0000540
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000541<li>The MC assembler now generates much better diagnostics for common errors,
Chris Lattner1efe27e2011-04-06 00:45:11 +0000542 is much faster at matching instructions, is much more bug-compatible with
543 the GAS assembler, and is now generally useful for a broad range of X86
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000544 assembly.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000545
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000546<li>We now have some basic <a href="CodeGenerator.html#mc">internals
547 documentation</a> for MC.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000548
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000549<li>.td files can now specify assembler aliases directly with the <a
550 href="CodeGenerator.html#na_instparsing">MnemonicAlias and InstAlias</a>
551 tblgen classes.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000552
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000553<li>LLVM now has an experimental format-independent object file manipulation
554 library (lib/Object). It supports both PE/COFF and ELF. The llvm-nm tool has
555 been extended to work with native object files, and the new llvm-objdump tool
556 supports disassembly of object files (but no relocations are displayed yet).
557</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000558
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000559<li>Win32 PE-COFF support in the MC assembler has made a lot of progress in the
560 2.9 timeframe, but is still not generally useful.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000561
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000562</ul>
563
564<p>For more information, please see the <a
Chris Lattner4ba2b652010-09-30 16:31:33 +0000565href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
566LLVM MC Project Blog Post</a>.
567</p>
568
NAKAMURA Takumi45c435a2011-04-05 08:24:22 +0000569</div>
Chris Lattner4ba2b652010-09-30 16:31:33 +0000570
Chris Lattner4ba2b652010-09-30 16:31:33 +0000571<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000572<h2>
Chris Lattner511433e2009-03-02 03:24:11 +0000573<a name="codegen">Target Independent Code Generator Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000574</h2>
Chris Lattner0b832202008-06-08 02:45:07 +0000575
576<div class="doc_text">
577
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000578<p>We have put a significant amount of work into the code generator
579infrastructure, which allows us to implement more aggressive algorithms and make
580it run faster:</p>
Chris Lattner0b832202008-06-08 02:45:07 +0000581
582<ul>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000583<li>The pre-register-allocation (preRA) instruction scheduler models register
584 pressure much more accurately in some cases. This allows the adoption of more
Chris Lattner49123fd2011-04-06 06:29:50 +0000585 aggressive scheduling heuristics without causing spills to be generated.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000586</li>
587
Chris Lattner49123fd2011-04-06 06:29:50 +0000588<li>LiveDebugVariables is a new pass that keeps track of debugging information
589 for user variables that are promoted to registers in optimized builds.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000590
Chris Lattner49123fd2011-04-06 06:29:50 +0000591<li>The scheduler now models operand latency and pipeline forwarding.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000592
Chris Lattner49123fd2011-04-06 06:29:50 +0000593<li>A major register allocator infrastructure rewrite is underway. It is not on
594 by default for 2.9 and you are not advised to use it, but it has made
595 substantial progress in the 2.9 timeframe:
596 <ul>
597 <li>A new -regalloc=basic "basic" register allocator can be used as a simple
598 fallback when debugging. It uses the new infrastructure.</li>
599 <li>New infrastructure is in place for live range splitting. "SplitKit" can
600 break a live interval into smaller pieces while preserving SSA form, and
601 SpillPlacement can help find the best split points. This is a work in
602 progress so the API is changing quickly.</li>
603 <li>The inline spiller has learned to clean up after live range splitting. It
604 can hoist spills out of loops, and it can eliminate redundant spills.</li>
605 <li>Rematerialization works with live range splitting.</li>
606 <li>The new "greedy" register allocator using live range splitting. This will
607 be the default register allocator in the next LLVM release, but it is not
608 turned on by default in 2.9.</li>
609 </ul>
610</li>
Chris Lattner84977642007-09-21 03:54:09 +0000611</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000612</div>
613
Chris Lattner917cc712009-03-02 02:37:32 +0000614<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000615<h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000616<a name="x86">X86-32 and X86-64 Target Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000617</h2>
Chris Lattner917cc712009-03-02 02:37:32 +0000618
619<div class="doc_text">
Chris Lattner7714c912010-10-04 04:39:25 +0000620<p>New features and major changes in the X86 target include:
Chris Lattner917cc712009-03-02 02:37:32 +0000621</p>
622
623<ul>
Chris Lattner49123fd2011-04-06 06:29:50 +0000624<li>LLVM 2.9 includes a complete reimplementation of the MMX instruction set.
625 The reimplementation uses a new LLVM IR <a
626 href="LangRef.html#t_x86mmx">x86_mmx</a> type to ensure that MMX operations
627 are <em>only</em> generated from source that uses MMX builtin operations. With
Duncan Sandsf3ba7af2011-04-06 08:07:40 +0000628 this, random types like &lt;2 x i32&gt; are not turned into MMX operations
Chris Lattner49123fd2011-04-06 06:29:50 +0000629 (which can be catastrophic without proper "emms" insertion). Because the X86
630 code generator always generates reliable code, the -disable-mmx flag is now
631 removed.
Chris Lattner1efe27e2011-04-06 00:45:11 +0000632</li>
633
Chris Lattner49123fd2011-04-06 06:29:50 +0000634<li>X86 support for FS/GS relative loads and stores using <a
Jay Foadcb88ec32011-04-06 07:55:30 +0000635 href="CodeGenerator.html#x86_memory">address space 256/257</a> works reliably
Chris Lattner49123fd2011-04-06 06:29:50 +0000636 now.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000637
Chris Lattner49123fd2011-04-06 06:29:50 +0000638<li>LLVM 2.9 generates much better code in several cases by using adc/sbb to
639 avoid generation of conditional move instructions for conditional increment
640 and other idioms.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000641
Chris Lattner49123fd2011-04-06 06:29:50 +0000642<li>The X86 backend has adopted a new preRA scheduling mode, "list-ilp", to
643 shorten the height of instruction schedules without inducing register spills.
644</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000645
Jay Foadcb88ec32011-04-06 07:55:30 +0000646<li>The MC assembler supports 3dNow! and 3DNowA instructions.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000647
Chris Lattner49123fd2011-04-06 06:29:50 +0000648<li>Several bugs have been fixed for Windows x64 code generator.</li>
Chris Lattner917cc712009-03-02 02:37:32 +0000649</ul>
650
Chris Lattner917cc712009-03-02 02:37:32 +0000651</div>
Chris Lattner84977642007-09-21 03:54:09 +0000652
653<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000654<h2>
Chris Lattner61358ab2009-10-13 17:48:04 +0000655<a name="ARM">ARM Target Improvements</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000656</h2>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000657
658<div class="doc_text">
Chris Lattner61358ab2009-10-13 17:48:04 +0000659<p>New features of the ARM target include:
660</p>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000661
662<ul>
Chris Lattner49123fd2011-04-06 06:29:50 +0000663<li>The ARM backend now has a fast instruction selector, which dramatically
664 improves -O0 compile times.</li>
665<li>The ARM backend has new tuning for Cortex-A8 and Cortex-A9 CPUs.</li>
666<li>The __builtin_prefetch builtin (and llvm.prefetch intrinsic) is compiled
667 into prefetch instructions instead of being discarded.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000668
669<li> The ARM backend preRA scheduler now models machine resources at cycle
670 granularity. This allows the scheduler to both accurately model
671 instruction latency and avoid overcommitting functional units.</li>
672
Chris Lattner49123fd2011-04-06 06:29:50 +0000673<li>Countless ARM microoptimizations have landed in LLVM 2.9.</li>
Bob Wilsone8472772010-09-13 17:39:35 +0000674</ul>
Chris Lattner61358ab2009-10-13 17:48:04 +0000675</div>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000676
677<!--=========================================================================-->
678<h2>
679<a name="OtherTS">Other Target Specific Improvements</a>
680</h2>
Chris Lattnerc441fb82009-03-01 02:30:21 +0000681
Chris Lattner1efe27e2011-04-06 00:45:11 +0000682<div class="doc_text">
683<ul>
Chris Lattner49123fd2011-04-06 06:29:50 +0000684<li>MicroBlaze: major updates for aggressive delay slot filler, MC-based
685 assembly printing, assembly instruction parsing, ELF .o file emission, and MC
686 instruction disassembler have landed.</li>
687
688<li>SPARC: Many improvements, including using the Y registers for
689 multiplications and addition of a simple delay slot filler.</li>
690
691<li>PowerPC: The backend has been largely MC'ized and is ready to support
Duncan Sandsf3ba7af2011-04-06 08:07:40 +0000692 directly writing out mach-o object files. No one seems interested in finishing
Chris Lattner49123fd2011-04-06 06:29:50 +0000693 this final step though.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000694
695</ul>
696</div>
Chris Lattner77d29b12008-06-05 08:02:49 +0000697
698<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000699<h2>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000700<a name="changes">Major Changes and Removed Features</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000701</h2>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000702
703<div class="doc_text">
704
Chris Lattnereeb4da02008-10-13 22:06:31 +0000705<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000706on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
Chris Lattnereeb4da02008-10-13 22:06:31 +0000707from the previous release.</p>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000708
709<ul>
Chris Lattner49123fd2011-04-06 06:29:50 +0000710<li><b>This is the last release to support the llvm-gcc frontend.</b></li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000711
Chris Lattner49123fd2011-04-06 06:29:50 +0000712<li>LLVM has a new <a href="CodingStandards.html#ll_naming">naming
713 convention standard</a>, though the codebase hasn't fully adopted it yet.</li>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000714
Chris Lattner49123fd2011-04-06 06:29:50 +0000715<li>The new DIBuilder class provides a simpler interface for front ends to
716 encode debug info in LLVM IR, and has replaced DIFactory.</li>
Chris Lattnerc5ac61d2011-04-06 05:50:04 +0000717
Chris Lattner49123fd2011-04-06 06:29:50 +0000718<li>LLVM IR and other tools always work on normalized target triples (which have
719 been run through <tt>Triple::normalize</tt>).</li>
720
721<li>The target triple x86_64--mingw64 is obsoleted. Use x86_64--mingw32
722 instead.</li>
723
724<li>The PointerTracking pass has been removed from mainline, and moved to The
725 ClamAV project (its only client).</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000726
Chris Lattner49123fd2011-04-06 06:29:50 +0000727<li>The LoopIndexSplit, LiveValues, SimplifyHalfPowrLibCalls, GEPSplitter, and
728 PartialSpecialization passes were removed. They were unmaintained,
Duncan Sandsf3ba7af2011-04-06 08:07:40 +0000729 buggy, or deemed to be a bad idea.</li>
Devang Patelb34dd132008-10-14 20:03:43 +0000730</ul>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000731
Chris Lattnerf6662f92008-10-13 17:57:36 +0000732</div>
733
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000734<!--=========================================================================-->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000735<h2>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000736<a name="api_changes">Internal API Changes</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000737</h2>
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000738
739<div class="doc_text">
740
Chris Lattner1efe27e2011-04-06 00:45:11 +0000741<p>In addition, many APIs have changed in this release. Some of the major
742 LLVM API changes are:</p>
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000743
744<ul>
Chris Lattner49123fd2011-04-06 06:29:50 +0000745<li>include/llvm/System merged into include/llvm/Support.</li>
746<li>The <a href="http://llvm.org/PR5207">llvm::APInt API</a> was significantly
747 cleaned up.</li>
Chris Lattner1efe27e2011-04-06 00:45:11 +0000748
Chris Lattner49123fd2011-04-06 06:29:50 +0000749<li>In the code generator, MVT::Flag was renamed to MVT::Glue to more accurately
750 describe its behavior.</li>
751
752<li>The system_error header from C++0x was added, and is now pervasively used to
753 capture and handle i/o and other errors in LLVM.</li>
754
755<li>The old sys::Path API has been deprecated in favor of the new PathV2 API,
756 which is more efficient and flexible.</li>
Daniel Dunbarf0233c62010-10-04 20:11:41 +0000757</ul>
758</div>
Chris Lattnerf6662f92008-10-13 17:57:36 +0000759
Chris Lattner79c3fe12003-10-02 04:57:28 +0000760<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000761<h1>
Misha Brukman500bc302003-11-22 00:38:41 +0000762 <a name="knownproblems">Known Problems</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000763</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000764<!-- *********************************************************************** -->
765
Misha Brukman500bc302003-11-22 00:38:41 +0000766<div class="doc_text">
767
Mikhail Glushenkovf795ef02009-03-01 18:09:47 +0000768<p>This section contains significant known problems with the LLVM system,
Chris Lattnere18b32e2008-11-10 05:40:34 +0000769listed by component. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000770href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000771there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000772
Misha Brukman500bc302003-11-22 00:38:41 +0000773</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000774
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000775<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000776<h2>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000777 <a name="experimental">Experimental features included with this release</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000778</h2>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000779
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000780<div class="doc_text">
781
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000782<p>The following components of this LLVM release are either untested, known to
783be broken or unreliable, or are in early development. These components should
784not be relied on, and bugs should not be filed against them, but they may be
785useful to some people. In particular, if you would like to work on one of these
Chris Lattner2b659ef2008-02-12 06:29:45 +0000786components, please contact us on the <a
787href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000788
789<ul>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000790<li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ
Chris Lattnerbb117712010-10-04 01:29:06 +0000791 and XCore backends are experimental.</li>
Chris Lattner7d9b6b42010-10-02 21:59:30 +0000792<li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
Chris Lattner49123fd2011-04-06 06:29:50 +0000793 other than darwin and ELF X86 systems.</li>
Chris Lattnerbe2e1b52011-03-10 07:43:44 +0000794
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000795</ul>
796
797</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000798
Misha Brukman500bc302003-11-22 00:38:41 +0000799<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000800<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000801 <a name="x86-be">Known problems with the X86 back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000802</h2>
John Criswellc0c186d2005-11-08 21:11:33 +0000803
804<div class="doc_text">
805
806<ul>
Anton Korobeynikova6094be2008-06-08 10:24:13 +0000807 <li>The X86 backend does not yet support
808 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
809 floating point stack</a>. It supports the 'f' and 't' constraints, but not
810 'u'.</li>
Dan Gohman8207ba92008-06-08 23:05:11 +0000811 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner914ce462010-04-22 06:28:20 +0000812 <tt>va_arg</tt>. Currently, front-ends support variadic
Dan Gohman8207ba92008-06-08 23:05:11 +0000813 argument constructs on X86-64 by lowering them manually.</li>
NAKAMURA Takumi45c435a2011-04-05 08:24:22 +0000814 <li>Windows x64 (aka Win64) code generator has a few issues.
815 <ul>
816 <li>llvm-gcc cannot build the mingw-w64 runtime currently
817 due to lack of support for the 'u' inline assembly
818 constraint and for X87 floating point inline assembly.</li>
819 <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt>
820 due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
821 It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
822 <li>Miss-aligned MOVDQA might crash your program. It is due to
823 <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>,
824 lack of handling aligned internal globals.</li>
825 </ul>
826 </li>
827
Chris Lattner26299222006-11-18 07:51:14 +0000828</ul>
829
830</div>
831
832<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000833<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000834 <a name="ppc-be">Known problems with the PowerPC back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000835</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000836
837<div class="doc_text">
838
839<ul>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000840<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000841compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000842</ul>
843
844</div>
845
846<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000847<h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000848 <a name="arm-be">Known problems with the ARM back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000849</h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000850
851<div class="doc_text">
852
853<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000854<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000855processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000856results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswell524a5dd2009-03-02 15:28:15 +0000857<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000858</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000859</ul>
860
861</div>
862
863<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000864<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000865 <a name="sparc-be">Known problems with the SPARC back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000866</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000867
868<div class="doc_text">
869
870<ul>
John Criswell524a5dd2009-03-02 15:28:15 +0000871<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Chris Lattner26299222006-11-18 07:51:14 +0000872 support the 64-bit SPARC ABI (-m64).</li>
873</ul>
874
875</div>
876
877<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000878<h2>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000879 <a name="mips-be">Known problems with the MIPS back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000880</h2>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000881
882<div class="doc_text">
883
884<ul>
Bruno Cardoso Lopesb7e1a4f2008-10-25 14:56:26 +0000885<li>64-bit MIPS targets are not supported yet.</li>
886</ul>
887
888</div>
889
890<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000891<h2>
Chris Lattner26299222006-11-18 07:51:14 +0000892 <a name="alpha-be">Known problems with the Alpha back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000893</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000894
895<div class="doc_text">
896
897<ul>
898
899<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
900appropriate nops inserted to ensure restartability.</li>
901
John Criswellc0c186d2005-11-08 21:11:33 +0000902</ul>
903</div>
904
Chris Lattner26299222006-11-18 07:51:14 +0000905<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000906<h2>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000907 <a name="c-be">Known problems with the C back-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000908</h2>
Chris Lattner26299222006-11-18 07:51:14 +0000909
910<div class="doc_text">
911
Chris Lattner3016ee92010-09-29 05:34:42 +0000912<p>The C backend has numerous problems and is not being actively maintained.
913Depending on it for anything serious is not advised.</p>
914
Chris Lattner26299222006-11-18 07:51:14 +0000915<ul>
Chris Lattner5733b272008-06-05 06:35:40 +0000916<li><a href="http://llvm.org/PR802">The C backend has only basic support for
917 inline assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000918<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
919 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greif4906abe2009-03-02 12:02:51 +0000920 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsf74c0cc2008-02-10 13:40:55 +0000921<li>The C backend does not support all exception handling constructs.</li>
Duncan Sands50723a92009-02-25 11:51:54 +0000922<li>The C backend does not support arbitrary precision integers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000923</ul>
924
925</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000926
Misha Brukman500bc302003-11-22 00:38:41 +0000927
928<!-- ======================================================================= -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000929<h2>
Chris Lattner3016ee92010-09-29 05:34:42 +0000930 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000931</h2>
Chris Lattner47588f92003-10-02 05:07:23 +0000932
Misha Brukman500bc302003-11-22 00:38:41 +0000933<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000934
Chris Lattner49123fd2011-04-06 06:29:50 +0000935<p><b>LLVM 2.9 will be the last release of llvm-gcc.</b></p>
936
Chris Lattner3016ee92010-09-29 05:34:42 +0000937<p>llvm-gcc is generally very stable for the C family of languages. The only
938 major language feature of GCC not supported by llvm-gcc is the
939 <tt>__builtin_apply</tt> family of builtins. However, some extensions
940 are only supported on some targets. For example, trampolines are only
941 supported on some targets (these are used when you take the address of a
942 nested function).</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000943
Chris Lattner3016ee92010-09-29 05:34:42 +0000944<p>Fortran support generally works, but there are still several unresolved bugs
945 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
946 tools/gfortran component for details. Note that llvm-gcc is missing major
947 Fortran performance work in the frontend and library that went into GCC after
948 4.2. If you are interested in Fortran, we recommend that you consider using
949 <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000950
Duncan Sands3af96332010-10-04 10:06:56 +0000951<p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
952actively maintained. If you are interested in Ada, we recommend that you
953consider using <a href="#dragonegg">dragonegg</a> instead.</p>
Chris Lattner2b659ef2008-02-12 06:29:45 +0000954</div>
955
Chris Lattner79c3fe12003-10-02 04:57:28 +0000956<!-- *********************************************************************** -->
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000957<h1>
Misha Brukman500bc302003-11-22 00:38:41 +0000958 <a name="additionalinfo">Additional Information</a>
NAKAMURA Takumic6319312011-04-05 21:55:14 +0000959</h1>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000960<!-- *********************************************************************** -->
961
Misha Brukman500bc302003-11-22 00:38:41 +0000962<div class="doc_text">
963
Chris Lattner416db102005-05-16 17:13:10 +0000964<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000965href="http://llvm.org">LLVM web page</a>, in particular in the <a
966href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000967contains versions of the API documentation which is up-to-date with the
968Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000969You can access versions of these documents specific to this release by going
970into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000971
Misha Brukman500bc302003-11-22 00:38:41 +0000972<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000973us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000974lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000975
Misha Brukman500bc302003-11-22 00:38:41 +0000976</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000977
978<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000979
Misha Brukman500bc302003-11-22 00:38:41 +0000980<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000981<address>
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Misha Brukman2061e892003-11-22 01:23:39 +0000986
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000987 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000988 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000989</address>
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