Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / aea8c7572d6b75cbab233097c720fc386efcd9c8 / . / docs / ReleaseNotes.html
blob: 2bc3f0f533fffad65793be01977f09ce5e77df0c [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css">
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]7 <title>LLVM 2.5 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]11<div class="doc_title">LLVM 2.5 Release Notes</div>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]12
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]13<ol>
14 <li><a href="#intro">Introduction</a></li>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]15 <li><a href="#subproj">Sub-project Status Update</a></li>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]16 <li><a href="#externalproj">External Projects Using LLVM 2.5</a></li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]17 <li><a href="#whatsnew">What's New in LLVM 2.5?</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]18 <li><a href="GettingStarted.html">Installation Instructions</a></li>
19 <li><a href="#portability">Portability and Supported Platforms</a></li>
Dan Gohman0de549c2008-10-14 16:23:02 +0000[diff] [blame]20 <li><a href="#knownproblems">Known Problems</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]21 <li><a href="#additionalinfo">Additional Information</a></li>
22</ol>
23
24<div class="doc_author">
Dan Gohman0de549c2008-10-14 16:23:02 +0000[diff] [blame]25 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]26</div>
27
28<!-- *********************************************************************** -->
29<div class="doc_section">
30 <a name="intro">Introduction</a>
31</div>
32<!-- *********************************************************************** -->
33
34<div class="doc_text">
35
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]36<p>This document contains the release notes for the LLVM Compiler
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]37Infrastructure, release 2.5. Here we describe the status of LLVM, including
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]38major improvements from the previous release and significant known problems.
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]39All LLVM releases may be downloaded from the <a
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]40href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]41
42<p>For more information about LLVM, including information about the latest
43release, please check out the <a href="http://llvm.org/">main LLVM
44web site</a>. If you have questions or comments, the <a
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
46List</a> is a good place to send them.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]47
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]48<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]49main LLVM web page, this document applies to the <i>next</i> release, not the
Gabor Greif7c65c4f2008-10-14 11:00:32 +0000[diff] [blame]50current one. To see the release notes for a specific release, please see the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]51<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]52
53</div>
54
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]55<!-- Unfinished features in 2.5:
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]56 Machine LICM
57 Machine Sinking
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]58 target-specific intrinsics
59 gold lto plugin
Chris Lattner56b64702009-02-25 07:32:53 +0000[diff] [blame]60 pre-alloc splitter, strong phi elim
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]61 <tt>llc -enable-value-prop</tt>, propagation of value info
62 (sign/zero ext info) from one MBB to another
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]63 debug info for optimized code
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]64 interpreter + libffi
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]65 postalloc scheduler: anti dependence breaking, hazard recognizer?
66
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]67initial support for debug line numbers when optimization enabled, not useful in
68 2.5 but will be for 2.6.
69
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]70 -->
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]71
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame]72 <!-- for announcement email:
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]73 -->
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]74
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]75<!-- *********************************************************************** -->
76<div class="doc_section">
77 <a name="subproj">Sub-project Status Update</a>
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]78</div>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]79<!-- *********************************************************************** -->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]80
81<div class="doc_text">
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]82<p>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]83The LLVM 2.5 distribution currently consists of code from the core LLVM
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]84repository &mdash;which roughly includes the LLVM optimizers, code generators
85and supporting tools &mdash; and the llvm-gcc repository. In addition to this
86code, the LLVM Project includes other sub-projects that are in development. The
87two which are the most actively developed are the <a href="#clang">Clang
88Project</a> and the <a href="#vmkit">VMKit Project</a>.
Bill Wendlingdde41b82009-03-02 04:28:57 +0000[diff] [blame]89</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]90
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]91</div>
92
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]93
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]94<!--=========================================================================-->
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]95<div class="doc_subsection">
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]96<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]97</div>
98
99<div class="doc_text">
100
101<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]102a set of new 'LLVM native' front-end technologies for the LLVM optimizer and
103code generator. While Clang is not included in the LLVM 2.5 release, it is
104continuing to make major strides forward in all areas. Its C and Objective-C
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]105parsing and code generation support is now very solid. For example, it is
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]106capable of successfully building many real-world applications for X86-32
107andX86-64,
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]108including <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">the FreeBSD
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]109kernel</a>. C++ is also
110making <a href="http://clang.llvm.org/cxx_status.html">incredible progress</a>,
111and work on templates has recently started.</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]112
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]113<p>While Clang is not yet production quality, it is progressing very nicely and
114is quite usable for building many C and Objective-C applications. If you are
115interested in fast compiles and good diagnostics, we encourage you to try it out
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]116by <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]117and reporting any issues you hit to the <a
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]118href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
119list</a>.</p>
120
121<p>In the LLVM 2.5 time-frame, the Clang team has made many improvements:</p>
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]122
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]123<ul>
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]124<li>Clang now has a new driver, which is focused on providing a GCC-compatible
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]125 interface.</li>
126<li>The X86-64 ABI is now supported.</li>
127<li>Precompiled header support is now implemented.</li>
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]128<li>Objective-C support is significantly improved beyond LLVM 2.4, supporting
129 many features, such as Objective-C Garbage Collection.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]130<li>Many many bugs are fixed and many features have been added.</li>
Bill Wendlinga8fb81d2009-03-02 04:28:18 +0000[diff] [blame]131</ul>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]132</div>
133
134<!--=========================================================================-->
135<div class="doc_subsection">
136<a name="clangsa">Clang Static Analyzer</a>
137</div>
138
139<div class="doc_text">
140
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]141<p>Previously announced in the last LLVM release, the Clang project also
142includes an early stage static source code analysis tool for <a
143href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
144in C and Objective-C programs. The tool performs a growing set of checks to find
145bugs that occur on a specific path within a program.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]146
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]147<p>In the LLVM 2.5 time-frame there have been many significant improvements to
148the analyzer's core path simulation engine and machinery for generating
149path-based bug reports to end-users. Particularly noteworthy improvements
150include experimental support for full field-sensitivity and reasoning about heap
151objects as well as an improved value-constraints subengine that does a much
152better job of reasoning about inequality relationships (e.g., <tt>x &gt; 2</tt>)
153between variables and constants.
Ted Kremenek0437b2c2008-10-14 05:14:21 +0000[diff] [blame]154
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]155<p>The set of checks performed by the static analyzer continues to expand, and
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]156future plans for the tool include full source-level inter-procedural analysis
157and deeper checks such as buffer overrun detection. There are many opportunities
158to extend and enhance the static analyzer, and anyone interested in working on
159this project is encouraged to get involved!</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]160
161</div>
162
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]163<!--=========================================================================-->
164<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]165<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]166</div>
167
168<div class="doc_text">
169<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]170The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]171a JVM and a CLI Virtual Machines (Microsoft .NET is an
172implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
173
Nicolas Geoffray8c3565e2009-03-02 09:25:38 +0000[diff] [blame]174<p>Following LLVM 2.5, VMKit has its second release that you can find on its
Nicolas Geoffray20cfdd42008-10-15 20:25:04 +0000[diff] [blame]175<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
176bug fixes, cleanup and new features. The major changes are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]177
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]178<ul>
179
Chris Lattner47bcf612009-02-26 05:20:36 +0000[diff] [blame]180<li>Ahead of Time compiler: compiles .class files to llvm .bc. VMKit uses this
Gabor Greifed585c62009-03-02 11:34:51 +0000[diff] [blame]181functionality to native compile the standard classes (e.g. java.lang.String).
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]182Users can compile AoT .class files into dynamic libraries and run them with the
Chris Lattner47bcf612009-02-26 05:20:36 +0000[diff] [blame]183help of VMKit.</li>
184
185<li>New exception model: the dwarf exception model is very slow for
186exception-intensive applications, so the JVM has had a new implementation of
187exceptions which check at each function call if an exception happened. There is
188a low performance penalty on applications without exceptions, but it is a big
189gain for exception-intensive applications. For example the jack benchmark in
190Spec JVM98 is 6x faster (performance gain of 83%).</li>
191
Nicolas Geoffray8c3565e2009-03-02 09:25:38 +0000[diff] [blame]192<li>User-level management of thread stacks, so that thread local data access
193at runtime is fast and portable. </li>
194
195<li>Implementation of biased locking for faster object synchronizations at
196runtime.</li>
197
198<li>New support for OSX/X64, Linux/X64 (with the Boehm GC) and Linux/ppc32.</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]199
200</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]201</div>
202
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]203<!-- *********************************************************************** -->
204<div class="doc_section">
205 <a name="externalproj">External Projects Using LLVM 2.5</a>
206</div>
207<!-- *********************************************************************** -->
208
209<!--=========================================================================-->
210<div class="doc_subsection">
211<a name="pure">Pure</a>
212</div>
213
214<div class="doc_text">
215<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]216<a href="http://pure-lang.googlecode.com/">Pure</a>
217is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]218Programs are collections of equations which are used to evaluate expressions in
219a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]220lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]221built-in list and matrix support (including list and matrix comprehensions) and
222an easy-to-use C interface. The interpreter uses LLVM as a backend to
223 JIT-compile Pure programs to fast native code.</p>
224
225<p>In addition to the usual algebraic data structures, Pure also has
226MATLAB-style matrices in order to support numeric computations and signal
227processing in an efficient way. Pure is mainly aimed at mathematical
228applications right now, but it has been designed as a general purpose language.
229The dynamic interpreter environment and the C interface make it possible to use
230it as a kind of functional scripting language for many application areas.
231</p>
232</div>
233
234
235<!--=========================================================================-->
236<div class="doc_subsection">
237<a name="ldc">LLVM D Compiler</a>
238</div>
239
240<div class="doc_text">
241<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]242<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
243the D Programming Language using the LLVM optimizer and code generator.
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]244The LDC project works great with the LLVM 2.5 release. General improvements in
245this
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]246cycle have included new inline asm constraint handling, better debug info
247support, general bugfixes, and better x86-64 support. This has allowed
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]248some major improvements in LDC, getting us much closer to being as
249fully featured as the original DMD compiler from DigitalMars.
250</p>
251</div>
252
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]253<!--=========================================================================-->
254<div class="doc_subsection">
255<a name="RoadsendPHP">Roadsend PHP</a>
256</div>
257
258<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]259<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
260source compiler for the PHP programming language that uses LLVM for its
261optimizer, JIT, and static compiler. This is a reimplementation of an earlier
262project that is now based on the LLVM.</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]263</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]264
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]265
266<!-- *********************************************************************** -->
267<div class="doc_section">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]268 <a name="whatsnew">What's New in LLVM 2.5?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]269</div>
270<!-- *********************************************************************** -->
271
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]272<div class="doc_text">
273
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]274<p>This release includes a huge number of bug fixes, performance tweaks, and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]275minor improvements. Some of the major improvements and new features are listed
276in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]277</p>
278</div>
279
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]280<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]281<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]282<a name="majorfeatures">Major New Features</a>
283</div>
284
285<div class="doc_text">
286
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]287<p>LLVM 2.5 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]288
289<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]290<li>LLVM 2.5 includes a brand new <a
291href="http://en.wikipedia.org/wiki/XCore">XCore</a> backend.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]292
Bill Wendling69afba82009-03-02 07:42:15 +0000[diff] [blame]293<li>llvm-gcc now generally supports the GFortran front-end, and the precompiled
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]294release binaries now support Fortran, even on Mac OS/X.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]295
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]296<li>CMake is now used by the <a href="GettingStartedVS.html">LLVM build process
297on Windows</a>. It automatically generates Visual Studio project files (and
298more) from a set of simple text files. This makes it much easier to
299maintain. In time, we'd like to standardize on CMake for everything.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]300
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]301<li>LLVM 2.5 now uses (and includes) Google Test for unit testing.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]302
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]303<li>The LLVM native code generator now supports arbitrary precision integers.
304Types like <tt>i33</tt> have long been valid in the LLVM IR, but were previously
305only supported by the interpreter. Note that the C backend still does not
306support these.</li>
Chris Lattner56b64702009-02-25 07:32:53 +0000[diff] [blame]307
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]308<li>LLVM 2.5 no longer uses 'bison,' so it is easier to build on Windows.</li>
Chris Lattner5ba16862008-02-10 08:18:42 +0000[diff] [blame]309</ul>
310
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]311</div>
312
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]313
314<!--=========================================================================-->
315<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]316<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]317</div>
318
319<div class="doc_text">
320
Chris Lattner4352cc82008-10-13 20:47:20 +0000[diff] [blame]321<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
322front-ends and driver with the LLVM optimizer and code generator. It currently
323includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]324
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]325<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]326<li>In this release, the GCC inliner is completely disabled. Previously the GCC
327inliner was used to handle always-inline functions and other cases. This caused
328problems with code size growth, and it is completely disabled in this
329release.</li>
330
331<li>llvm-gcc (and LLVM in general) now support code generation for stack
332canaries, which is an effective form of <a
333href="http://en.wikipedia.org/wiki/Stack-smashing_protection">buffer overflow
334protection</a>. llvm-gcc supports this with the <tt>-fstack-protector</tt>
335command line option (just like GCC). In LLVM IR, you can request code
336generation for stack canaries with function attributes.
337</li>
Gabor Greif0e49cc82008-06-09 06:06:18 +0000[diff] [blame]338</ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]339
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]340</div>
341
342
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]343<!--=========================================================================-->
344<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]345<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]346</div>
347
348<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]349<p>LLVM IR has several new features that are used by our existing front-ends and
350can be useful if you are writing a front-end for LLVM:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]351
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]352<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]353<li>The <a href="LangRef.html#i_shufflevector">shufflevector</a> instruction
354has been generalized to allow different shuffle mask width than its input
355vectors. This allows you to use shufflevector to combine two
356"&lt;4 x float&gt;" vectors into a "&lt;8 x float&gt;" for example.</li>
357
358<li>LLVM IR now supports new intrinsics for computing and acting on <a
359href="LangRef.html#int_overflow">overflow of integer operations</a>. This allows
360efficient code generation for languages that must trap or throw an exception on
361overflow. While these intrinsics work on all targets, they only generate
362efficient code on X86 so far.</li>
363
364<li>LLVM IR now supports a new <a href="LangRef.html#linkage">private
365linkage</a> type to produce labels that are stripped by the assembler before it
366produces a .o file (thus they are invisible to the linker).</li>
367
368<li>LLVM IR supports two new attributes for better alias analysis. The <a
369href="LangRef.html#paramattrs">noalias</a> attribute can now be used on the
370return value of a function to indicate that it returns new memory (e.g.
371'malloc', 'calloc', etc).</li>
372
373<li>The new <a href="LangRef.html#paramattrs">nocapture</a> attribute can be
374used on pointer arguments to functions that access through but do not return the
375pointer in a data structure that out lives the call (e.g. 'strlen', 'memcpy',
376and many others). The simplifylibcalls pass applies these attributes to
377standard libc functions.</li>
378
379<li>The parser for ".ll" files in lib/AsmParser is now completely rewritten as a
380recursive descent parser. This parser produces better error messages (including
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]381caret diagnostics), is less fragile (less likely to crash on strange things),
382does not leak memory, is more efficient, and eliminates LLVM's last use of the
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]383'bison' tool.</li>
384
385<li>Debug information representation and manipulation internals have been
386 consolidated to use a new set of classes in
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]387 <tt>llvm/Analysis/DebugInfo.h</tt>. These routines are more
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]388 efficient, robust, and extensible and replace the older mechanisms.
389 llvm-gcc, clang, and the code generator now use them to create and process
390 debug information.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]391
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]392</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]393
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]394</div>
395
396<!--=========================================================================-->
397<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]398<a name="optimizer">Optimizer Improvements</a>
399</div>
400
401<div class="doc_text">
402
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]403<p>In addition to a large array of bug fixes and minor performance tweaks, this
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]404release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]405
406<ul>
407
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]408<li>The loop optimizer now improves floating point induction variables in
409several ways, including adding shadow induction variables to avoid
410"integer &lt;-&gt; floating point" conversions in loops when safe.</li>
411
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]412<li>The "-mem2reg" pass is now much faster on code with large basic blocks.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]413
414<li>The "-jump-threading" pass is more powerful: it is iterative
415 and handles threading based on values with fully and partially redundant
416 loads.</li>
417
418<li>The "-memdep" memory dependence analysis pass (used by GVN and memcpyopt) is
419 both faster and more aggressive.</li>
420
421<li>The "-scalarrepl" scalar replacement of aggregates pass is more aggressive
422 about promoting unions to registers.</li>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]423
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]424</ul>
425
426</div>
427
428<!--=========================================================================-->
429<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]430<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]431</div>
432
433<div class="doc_text">
434
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]435<p>We have put a significant amount of work into the code generator
436infrastructure, which allows us to implement more aggressive algorithms and make
437it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]438
439<ul>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]440<li>The <a href="WritingAnLLVMBackend.html">Writing an LLVM Compiler
441Backend</a> document has been greatly expanded and is substantially more
442complete.</li>
443
444<li>The SelectionDAG type legalization logic has been completely rewritten, is
445now more powerful (it supports arbitrary precision integer types for example),
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]446and is more correct in several corner cases. The type legalizer converts
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]447operations on types that are not natively supported by the target machine into
448equivalent code sequences that only use natively supported types. The old type
449legalizer is still available (for now) and will be used if
450<tt>-disable-legalize-types</tt> is passed to the code generator.
Duncan Sands335d5e42009-02-25 11:50:08 +0000[diff] [blame]451</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]452
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]453<li>The code generator now supports widening illegal vectors to larger legal
454ones (for example, converting operations on &lt;3 x float&gt; to work on
455&lt;4 x float&gt;) which is very important for common graphics
456applications.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]457
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]458<li>The assembly printers for each target are now split out into their own
459libraries that are separate from the main code generation logic. This reduces
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]460the code size of JIT compilers by not requiring them to be linked in.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]461
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]462<li>The 'fast' instruction selection path (used at -O0 and for fast JIT
463 compilers) now supports accelerating codegen for code that uses exception
464 handling constructs.</li>
465
466<li>The optional PBQP register allocator now supports register coalescing.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]467</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]468</div>
469
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]470<!--=========================================================================-->
471<div class="doc_subsection">
472<a name="x86">X86-32 and X86-64 Target Improvements</a>
473</div>
474
475<div class="doc_text">
476<p>New features of the X86 target include:
477</p>
478
479<ul>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]480<li>The <tt><a href="LangRef.html#int_returnaddress">llvm.returnaddress</a></tt>
481intrinsic (which is used to implement <tt>__builtin_return_address</tt>) now
482supports non-zero stack depths on X86.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]483
484<li>The X86 backend now supports code generation of vector shift operations
485using SSE instructions.</li>
486
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]487<li>X86-64 code generation now takes advantage of red zone, unless the
488<tt>-mno-red-zone</tt> option is specified.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]489
490<li>The X86 backend now supports using address space #256 in LLVM IR as a way of
491performing memory references off the GS segment register. This allows a
492front-end to take advantage of very low-level programming techniques when
Gabor Greifed585c62009-03-02 11:34:51 +0000[diff] [blame]493targeting X86 CPUs. See <tt>test/CodeGen/X86/movgs.ll</tt> for a simple
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]494example.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]495
496<li>The X86 backend now supports a <tt>-disable-mmx</tt> command line option to
497 prevent use of MMX even on chips that support it. This is important for cases
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]498 where code does not contain the proper <tt>llvm.x86.mmx.emms</tt>
499 intrinsics.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]500
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]501<li>The X86 JIT now detects the new Intel <a
502 href="http://en.wikipedia.org/wiki/Intel_Core_i7">Core i7</a> and <a
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]503 href="http://en.wikipedia.org/wiki/Intel_Atom">Atom</a> chips and
504 auto-configures itself appropriately for the features of these chips.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]505
506<li>The JIT now supports exception handling constructs on Linux/X86-64 and
507 Darwin/x86-64.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]508
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]509<li>The JIT supports Thread Local Storage (TLS) on Linux/X86-32 but not yet on
510 X86-64.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]511</ul>
512
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]513</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]514
515<!--=========================================================================-->
516<div class="doc_subsection">
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]517<a name="pic16">PIC16 Target Improvements</a>
518</div>
519
520<div class="doc_text">
521<p>New features of the PIC16 target include:
522</p>
523
524<ul>
525<li>Both direct and indirect load/stores work now.</li>
526<li>Logical, bitwise and conditional operations now work for integer data
527types.</li>
528<li>Function calls involving basic types work now.</li>
529<li>Support for integer arrays.</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]530<li>The compiler can now emit libcalls for operations not supported by m/c
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]531instructions.</li>
532<li>Support for both data and ROM address spaces.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]533</ul>
534
535<p>Things not yet supported:</p>
536
537<ul>
538<li>Floating point.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]539<li>Passing/returning aggregate types to and from functions.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]540<li>Variable arguments.</li>
541<li>Indirect function calls.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]542<li>Interrupts/programs.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]543<li>Debug info.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]544</ul>
545
546</div>
547
548
549<!--=========================================================================-->
550<div class="doc_subsection">
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]551<a name="llvmc">Improvements in LLVMC</a>
552</div>
553
554<div class="doc_text">
555<p>New features include:</p>
556
557<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]558<li>Beginning with LLVM 2.5, <tt>llvmc2</tt> is known as
559 just <tt>llvmc</tt>. The old <tt>llvmc</tt> driver was removed.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]560
561<li>The Clang plugin was substantially improved and is now enabled
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]562 by default. The command <tt>llvmc --clang</tt> can be now used as a
563 synonym to <tt>ccc</tt>.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]564
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]565<li>There is now a <tt>--check-graph</tt> option, which is supposed to catch
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]566 common errors like multiple default edges, mismatched output/input language
567 names and cycles. In general, these checks can't be done at compile-time
568 because of the need to support plugins.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]569
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]570<li>Plugins are now more flexible and can refer to compilation graph nodes and
571 options defined in other plugins. To manage dependencies, a priority-sorting
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]572 mechanism was introduced. This change affects the TableGen file syntax. See the
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]573 documentation for details.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]574
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]575<li>Hooks can now be provided with arguments. The syntax is "<tt>$CALL(MyHook,
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]576 'Arg1', 'Arg2', 'Arg3')</tt>".</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]577
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]578<li>A new option type: multi-valued option, for options that take more than one
579 argument (for example, "<tt>-foo a b c</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]580
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]581<li>New option properties: '<tt>one_or_more</tt>', '<tt>zero_or_more</tt>',
582'<tt>hidden</tt>' and '<tt>really_hidden</tt>'.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]583
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]584<li>The '<tt>case</tt>' expression gained an '<tt>error</tt>' action and
585 an '<tt>empty</tt>' test (equivalent to "<tt>(not (not_empty ...))</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]586
587<li>Documentation now looks more consistent to the rest of the LLVM
588 docs. There is also a man page now.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]589
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]590</ul>
591
592</div>
593
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]594
595<!--=========================================================================-->
596<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]597<a name="changes">Major Changes and Removed Features</a>
598</div>
599
600<div class="doc_text">
601
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]602<p>If you're already an LLVM user or developer with out-of-tree changes based
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]603on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]604from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]605
606<ul>
607
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]608<li>llvm-gcc defaults to <tt>-fno-math-errno</tt> on all X86 targets.</li>
609
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]610</ul>
611
612
613<p>In addition, many APIs have changed in this release. Some of the major LLVM
614API changes are:</p>
615
616<ul>
Gabor Greiff7ea27c2009-03-02 12:23:55 +0000[diff] [blame]617<li>Some deprecated interfaces to create <tt>Instruction</tt> subclasses, that
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]618 were spelled with lower case "create," have been removed.</li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]619</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]620
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]621</div>
622
623
624
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]625<!-- *********************************************************************** -->
626<div class="doc_section">
627 <a name="portability">Portability and Supported Platforms</a>
628</div>
629<!-- *********************************************************************** -->
630
631<div class="doc_text">
632
633<p>LLVM is known to work on the following platforms:</p>
634
635<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]636<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]637Linux, Fedora Core and FreeBSD (and probably other unix-like systems).</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]638<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]639and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]640<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]641<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
642 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]643<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]644<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]645<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]646</ul>
647
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]648<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]649to the machine and operating system on which it is built. However, minor
650porting may be required to get LLVM to work on new platforms. We welcome your
651portability patches and reports of successful builds or error messages.</p>
652
653</div>
654
655<!-- *********************************************************************** -->
656<div class="doc_section">
657 <a name="knownproblems">Known Problems</a>
658</div>
659<!-- *********************************************************************** -->
660
661<div class="doc_text">
662
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]663<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]664listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]665href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
666there isn't already one.</p>
667
668</div>
669
670<!-- ======================================================================= -->
671<div class="doc_subsection">
672 <a name="experimental">Experimental features included with this release</a>
673</div>
674
675<div class="doc_text">
676
677<p>The following components of this LLVM release are either untested, known to
678be broken or unreliable, or are in early development. These components should
679not be relied on, and bugs should not be filed against them, but they may be
680useful to some people. In particular, if you would like to work on one of these
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]681components, please contact us on the <a
682href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]683
684<ul>
Gabor Greifaa53e562008-10-14 11:31:14 +0000[diff] [blame]685<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame]686<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
687 supported value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]688</ul>
689
690</div>
691
692<!-- ======================================================================= -->
693<div class="doc_subsection">
694 <a name="x86-be">Known problems with the X86 back-end</a>
695</div>
696
697<div class="doc_text">
698
699<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]700 <li>The X86 backend does not yet support
701 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
702 floating point stack</a>. It supports the 'f' and 't' constraints, but not
703 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]704 <li>The X86 backend generates inefficient floating point code when configured
705 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]706 <li>Win64 code generation wasn't widely tested. Everything should work, but we
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]707 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
708 runtime currently due
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]709 to <a href="http://llvm.org/PR2255">several</a>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]710 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
711 the
712 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]713 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]714 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]715 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]716</ul>
717
718</div>
719
720<!-- ======================================================================= -->
721<div class="doc_subsection">
722 <a name="ppc-be">Known problems with the PowerPC back-end</a>
723</div>
724
725<div class="doc_text">
726
727<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]728<li>The Linux PPC32/ABI support needs testing for the interpreter and static
729compilation, and lacks support for debug information.</li>
730</ul>
731
732</div>
733
734<!-- ======================================================================= -->
735<div class="doc_subsection">
736 <a name="arm-be">Known problems with the ARM back-end</a>
737</div>
738
739<div class="doc_text">
740
741<ul>
742<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]743processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]744results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]745<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]746</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]747<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
748 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]749programs compiled with LLVM. Please use more recent versions of QEMU.</li>
750</ul>
751
752</div>
753
754<!-- ======================================================================= -->
755<div class="doc_subsection">
756 <a name="sparc-be">Known problems with the SPARC back-end</a>
757</div>
758
759<div class="doc_text">
760
761<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]762<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]763 support the 64-bit SPARC ABI (-m64).</li>
764</ul>
765
766</div>
767
768<!-- ======================================================================= -->
769<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]770 <a name="mips-be">Known problems with the MIPS back-end</a>
771</div>
772
773<div class="doc_text">
774
775<ul>
776<li>The O32 ABI is not fully supported.</li>
777<li>64-bit MIPS targets are not supported yet.</li>
778</ul>
779
780</div>
781
782<!-- ======================================================================= -->
783<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]784 <a name="alpha-be">Known problems with the Alpha back-end</a>
785</div>
786
787<div class="doc_text">
788
789<ul>
790
791<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
792appropriate nops inserted to ensure restartability.</li>
793
794</ul>
795</div>
796
797<!-- ======================================================================= -->
798<div class="doc_subsection">
799 <a name="ia64-be">Known problems with the IA64 back-end</a>
800</div>
801
802<div class="doc_text">
803
804<ul>
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]805<li>The Itanium backend is highly experimental and has a number of known
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]806 issues. We are looking for a maintainer for the Itanium backend. If you
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]807 are interested, please contact the LLVMdev mailing list.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]808</ul>
809
810</div>
811
812<!-- ======================================================================= -->
813<div class="doc_subsection">
814 <a name="c-be">Known problems with the C back-end</a>
815</div>
816
817<div class="doc_text">
818
819<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]820<li><a href="http://llvm.org/PR802">The C backend has only basic support for
821 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]822<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
823 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Gabor Greife33c5322009-03-02 12:02:51 +0000[diff] [blame]824 C++ code compiled with <tt>llc</tt> or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]825<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]826<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]827</ul>
828
829</div>
830
831
832<!-- ======================================================================= -->
833<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]834 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]835</div>
836
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]837<div class="doc_text">
838
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]839<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
840Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]841LLVMdev mailing list if you are interested.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]842
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]843<p>The only major language feature of GCC not supported by llvm-gcc is
844 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
845 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]846 supported on some targets (these are used when you take the address of a
847 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]848
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]849<p>If you run into GCC extensions which are not supported, please let us know.
850</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]851
852</div>
853
854<!-- ======================================================================= -->
855<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]856 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]857</div>
858
859<div class="doc_text">
860
861<p>The C++ front-end is considered to be fully
862tested and works for a number of non-trivial programs, including LLVM
863itself, Qt, Mozilla, etc.</p>
864
865<ul>
Anton Korobeynikovd9a17932008-10-11 18:27:16 +0000[diff] [blame]866<li>Exception handling works well on the X86 and PowerPC targets. Currently
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]867 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]868</ul>
869
870</div>
871
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]872<!-- ======================================================================= -->
873<div class="doc_subsection">
874 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
875</div>
876
877<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]878<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]879<li>Fortran support generally works, but there are still several unresolved bugs
880 in Bugzilla. Please see the tools/gfortran component for details.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]881
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]882<li>The Fortran front-end currently does not build on Darwin (without tweaks)
883 due to unresolved dependencies on the C front-end.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]884</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]885</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]886
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]887<!-- ======================================================================= -->
888<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]889 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]890</div>
891
892<div class="doc_text">
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]893The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
894technology, and problems should be expected.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]895<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]896<li>The Ada front-end currently only builds on X86-32. This is mainly due
John Criswellaea8c752009-03-02 15:28:15 +0000[diff] [blame^]897to lack of trampoline support (pointers to nested functions) on other platforms.
898However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]899which does support trampolines.</li>
900<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]901This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
902exception handling, which is used internally by the compiler.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]903Workaround: configure with --disable-bootstrap.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]904<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
905and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]906(c380004 also fails with gcc-4.2 mainline).
907If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
908causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]909<li>Some gcc specific Ada tests continue to crash the compiler.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]910<li>The -E binder option (exception backtraces)
911<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
912crashing if an exception is raised. Workaround: do not use -E.</li>
913<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
914or finish at a non-byte offset</a> in a record. Workaround: do not pack records
915or use representation clauses that result in a field of a non-discrete type
916starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]917<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
918'main' as generated by the Ada binder to be invalid</a>.
919Workaround: hand edit the file to use pointers for <tt>argv</tt> and
920<tt>envp</tt> rather than integers.</li>
921<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
922ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]923</ul>
924</div>
925
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]926<!-- *********************************************************************** -->
927<div class="doc_section">
928 <a name="additionalinfo">Additional Information</a>
929</div>
930<!-- *********************************************************************** -->
931
932<div class="doc_text">
933
934<p>A wide variety of additional information is available on the <a
935href="http://llvm.org">LLVM web page</a>, in particular in the <a
936href="http://llvm.org/docs/">documentation</a> section. The web page also
937contains versions of the API documentation which is up-to-date with the
938Subversion version of the source code.
939You can access versions of these documents specific to this release by going
940into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
941
942<p>If you have any questions or comments about LLVM, please feel free to contact
943us via the <a href="http://llvm.org/docs/#maillist"> mailing
944lists</a>.</p>
945
946</div>
947
948<!-- *********************************************************************** -->
949
950<hr>
951<address>
952 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]953 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]954 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]955 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]956
957 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
958 Last modified: $Date$
959</address>
960
961</body>
962</html>