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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 9c7c438f1ea9274011761194997facbc4605f133 / . / docs / ReleaseNotes.html
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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
Chris Lattner4f076402008-10-12 19:47:48 +0000[diff] [blame]61 llc -enable-value-prop, propagation of value info (sign/zero ext info) from
62 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
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]155<p>The set of checks performed by the static analyzer continue to expand, and
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
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]174<p>Following LLVM 2.5, VMKit has its first 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
181functionality to native compile the standard classes (eg java.lang.String).
182Users can compile AOT .class files into dynamic libraries and run them with the
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
192<li>New support for OSX/X64, Linux/X64 (with the Boehm GC), Linux/ppc32.</li>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]193
194</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]195</div>
196
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]197<!-- *********************************************************************** -->
198<div class="doc_section">
199 <a name="externalproj">External Projects Using LLVM 2.5</a>
200</div>
201<!-- *********************************************************************** -->
202
203<!--=========================================================================-->
204<div class="doc_subsection">
205<a name="pure">Pure</a>
206</div>
207
208<div class="doc_text">
209<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]210<a href="http://pure-lang.googlecode.com/">Pure</a>
211is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]212Programs are collections of equations which are used to evaluate expressions in
213a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]214lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]215built-in list and matrix support (including list and matrix comprehensions) and
216an easy-to-use C interface. The interpreter uses LLVM as a backend to
217 JIT-compile Pure programs to fast native code.</p>
218
219<p>In addition to the usual algebraic data structures, Pure also has
220MATLAB-style matrices in order to support numeric computations and signal
221processing in an efficient way. Pure is mainly aimed at mathematical
222applications right now, but it has been designed as a general purpose language.
223The dynamic interpreter environment and the C interface make it possible to use
224it as a kind of functional scripting language for many application areas.
225</p>
226</div>
227
228
229<!--=========================================================================-->
230<div class="doc_subsection">
231<a name="ldc">LLVM D Compiler</a>
232</div>
233
234<div class="doc_text">
235<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]236<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
237the D Programming Language using the LLVM optimizer and code generator.
Bill Wendling69afba82009-03-02 07:42:15 +0000[diff] [blame]238LDC project works great with the LLVM 2.5 release. General improvements in this
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]239cycle have included new inline asm constraint handling, better debug info
240support, general bugfixes, and better x86-64 support. This has allowed
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]241some major improvements in LDC, getting us much closer to being as
242fully featured as the original DMD compiler from DigitalMars.
243</p>
244</div>
245
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]246<!--=========================================================================-->
247<div class="doc_subsection">
248<a name="RoadsendPHP">Roadsend PHP</a>
249</div>
250
251<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]252<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
253source compiler for the PHP programming language that uses LLVM for its
254optimizer, JIT, and static compiler. This is a reimplementation of an earlier
255project that is now based on the LLVM.</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]256</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]257
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]258
259<!-- *********************************************************************** -->
260<div class="doc_section">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]261 <a name="whatsnew">What's New in LLVM 2.5?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]262</div>
263<!-- *********************************************************************** -->
264
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]265<div class="doc_text">
266
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]267<p>This release includes a huge number of bug fixes, performance tweaks, and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]268minor improvements. Some of the major improvements and new features are listed
269in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]270</p>
271</div>
272
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]273<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]274<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]275<a name="majorfeatures">Major New Features</a>
276</div>
277
278<div class="doc_text">
279
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]280<p>LLVM 2.5 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]281
282<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]283<li>LLVM 2.5 includes a brand new <a
284href="http://en.wikipedia.org/wiki/XCore">XCore</a> backend.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]285
Bill Wendling69afba82009-03-02 07:42:15 +0000[diff] [blame]286<li>llvm-gcc now generally supports the GFortran front-end, and the precompiled
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]287release binaries now support Fortran, even on Mac OS/X.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]288
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]289<li>CMake is now used by the <a href="GettingStartedVS.html">LLVM build process
290on Windows</a>. It automatically generates Visual Studio project files (and
291more) from a set of simple text files. This makes it much easier to
292maintain. In time, we'd like to standardize on CMake for everything.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]293
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]294<li>LLVM 2.5 now uses (and includes) Google Test for unit testing.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]295
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]296<li>The LLVM native code generator now supports arbitrary precision integers.
297Types like <tt>i33</tt> have long been valid in the LLVM IR, but were previously
298only supported by the interpreter. Note that the C backend still does not
299support these.</li>
Chris Lattner56b64702009-02-25 07:32:53 +0000[diff] [blame]300
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]301<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]302</ul>
303
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]304</div>
305
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]306
307<!--=========================================================================-->
308<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]309<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]310</div>
311
312<div class="doc_text">
313
Chris Lattner4352cc82008-10-13 20:47:20 +0000[diff] [blame]314<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
315front-ends and driver with the LLVM optimizer and code generator. It currently
316includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]317
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]318<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]319<li>In this release, the GCC inliner is completely disabled. Previously the GCC
320inliner was used to handle always-inline functions and other cases. This caused
321problems with code size growth, and it is completely disabled in this
322release.</li>
323
324<li>llvm-gcc (and LLVM in general) now support code generation for stack
325canaries, which is an effective form of <a
326href="http://en.wikipedia.org/wiki/Stack-smashing_protection">buffer overflow
327protection</a>. llvm-gcc supports this with the <tt>-fstack-protector</tt>
328command line option (just like GCC). In LLVM IR, you can request code
329generation for stack canaries with function attributes.
330</li>
Gabor Greif0e49cc82008-06-09 06:06:18 +0000[diff] [blame]331</ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]332
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]333</div>
334
335
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]336<!--=========================================================================-->
337<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]338<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]339</div>
340
341<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]342<p>LLVM IR has several new features that are used by our existing front-ends and
343can be useful if you are writing a front-end for LLVM:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]344
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]345<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]346<li>The <a href="LangRef.html#i_shufflevector">shufflevector</a> instruction
347has been generalized to allow different shuffle mask width than its input
348vectors. This allows you to use shufflevector to combine two
349"&lt;4 x float&gt;" vectors into a "&lt;8 x float&gt;" for example.</li>
350
351<li>LLVM IR now supports new intrinsics for computing and acting on <a
352href="LangRef.html#int_overflow">overflow of integer operations</a>. This allows
353efficient code generation for languages that must trap or throw an exception on
354overflow. While these intrinsics work on all targets, they only generate
355efficient code on X86 so far.</li>
356
357<li>LLVM IR now supports a new <a href="LangRef.html#linkage">private
358linkage</a> type to produce labels that are stripped by the assembler before it
359produces a .o file (thus they are invisible to the linker).</li>
360
361<li>LLVM IR supports two new attributes for better alias analysis. The <a
362href="LangRef.html#paramattrs">noalias</a> attribute can now be used on the
363return value of a function to indicate that it returns new memory (e.g.
364'malloc', 'calloc', etc).</li>
365
366<li>The new <a href="LangRef.html#paramattrs">nocapture</a> attribute can be
367used on pointer arguments to functions that access through but do not return the
368pointer in a data structure that out lives the call (e.g. 'strlen', 'memcpy',
369and many others). The simplifylibcalls pass applies these attributes to
370standard libc functions.</li>
371
372<li>The parser for ".ll" files in lib/AsmParser is now completely rewritten as a
373recursive descent parser. This parser produces better error messages (including
374caret diagnostics) is less fragile (less likely to crash on strange things) does
375not leak memory, is more efficient, and eliminates LLVM's last use of the
376'bison' tool.</li>
377
378<li>Debug information representation and manipulation internals have been
379 consolidated to use a new set of classes in
380 <tt>llvm/Analysis/DebugInfo.h</tt> classes. These routines are more
381 efficient, robust, and extensible and replace the older mechanisms.
382 llvm-gcc, clang, and the code generator now use them to create and process
383 debug information.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]384
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]385</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]386
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]387</div>
388
389<!--=========================================================================-->
390<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]391<a name="optimizer">Optimizer Improvements</a>
392</div>
393
394<div class="doc_text">
395
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]396<p>In addition to a huge array of bug fixes and minor performance tweaks, this
397release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]398
399<ul>
400
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]401<li>The loop optimizer now improves floating point induction variables in
402several ways, including adding shadow induction variables to avoid
403"integer &lt;-&gt; floating point" conversions in loops when safe.</li>
404
405<li>The "-mem2reg" pass is now much faster on code with huge basic blocks.</li>
406
407<li>The "-jump-threading" pass is more powerful: it is iterative
408 and handles threading based on values with fully and partially redundant
409 loads.</li>
410
411<li>The "-memdep" memory dependence analysis pass (used by GVN and memcpyopt) is
412 both faster and more aggressive.</li>
413
414<li>The "-scalarrepl" scalar replacement of aggregates pass is more aggressive
415 about promoting unions to registers.</li>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]416
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]417</ul>
418
419</div>
420
421<!--=========================================================================-->
422<div class="doc_subsection">
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]423<a name="codegen">Target Independent Code Generator Improvements</a>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]424</div>
425
426<div class="doc_text">
427
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]428<p>We have put a significant amount of work into the code generator
429infrastructure, which allows us to implement more aggressive algorithms and make
430it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]431
432<ul>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]433<li>The <a href="WritingAnLLVMBackend.html">Writing an LLVM Compiler
434Backend</a> document has been greatly expanded and is substantially more
435complete.</li>
436
437<li>The SelectionDAG type legalization logic has been completely rewritten, is
438now more powerful (it supports arbitrary precision integer types for example),
439and more correct in several corner cases. The type legalizer converts
440operations on types that are not natively supported by the target machine into
441equivalent code sequences that only use natively supported types. The old type
442legalizer is still available (for now) and will be used if
443<tt>-disable-legalize-types</tt> is passed to the code generator.
Duncan Sands335d5e42009-02-25 11:50:08 +0000[diff] [blame]444</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]445
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]446<li>The code generator now supports widening illegal vectors to larger legal
447ones (for example, converting operations on &lt;3 x float&gt; to work on
448&lt;4 x float&gt;) which is very important for common graphics
449applications.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]450
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]451<li>The assembly printers for each target are now split out into their own
452libraries that are separate from the main code generation logic. This reduces
453code size of JIT compilers by not requiring them to be linked in.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]454
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]455<li>The 'fast' instruction selection path (used at -O0 and for fast JIT
456 compilers) now supports accelerating codegen for code that uses exception
457 handling constructs.</li>
458
459<li>The optional PBQP register allocator now supports register coalescing.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]460</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]461</div>
462
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]463<!--=========================================================================-->
464<div class="doc_subsection">
465<a name="x86">X86-32 and X86-64 Target Improvements</a>
466</div>
467
468<div class="doc_text">
469<p>New features of the X86 target include:
470</p>
471
472<ul>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]473<li>The <tt><a href="LangRef.html#int_returnaddress">llvm.returnaddress</a></tt>
474intrinsic (which is used to implement <tt>__builtin_return_address</tt>) now
475supports non-zero stack depths on X86.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]476
477<li>The X86 backend now supports code generation of vector shift operations
478using SSE instructions.</li>
479
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]480<li>X86-64 code generation now takes advantage of red zone, unless the
481<tt>-mno-red-zone</tt> option is specified.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]482
483<li>The X86 backend now supports using address space #256 in LLVM IR as a way of
484performing memory references off the GS segment register. This allows a
485front-end to take advantage of very low-level programming techniques when
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]486targetting X86 CPUs. See <tt>test/CodeGen/X86/movgs.ll</tt> for a simple
487example.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]488
489<li>The X86 backend now supports a <tt>-disable-mmx</tt> command line option to
490 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^]491 where code does not contain the proper <tt>llvm.x86.mmx.emms</tt>
492 intrinsics.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]493
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]494<li>The X86 JIT now detects the new Intel <a
495 href="http://en.wikipedia.org/wiki/Intel_Core_i7">Core i7</a> and <a
496 href="http://en.wikipedia.org/wiki/Intel_Atom">Atom</a> chips;
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]497 auto-configuring itself appropriately for the features of these chips.</li>
498
499<li>The JIT now supports exception handling constructs on Linux/X86-64 and
500 Darwin/x86-64.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]501
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]502<li>The JIT supports Thread Local Storage (TLS) on Linux/X86-32 but not yet on
503 X86-64.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]504</ul>
505
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]506</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]507
508<!--=========================================================================-->
509<div class="doc_subsection">
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]510<a name="pic16">PIC16 Target Improvements</a>
511</div>
512
513<div class="doc_text">
514<p>New features of the PIC16 target include:
515</p>
516
517<ul>
518<li>Both direct and indirect load/stores work now.</li>
519<li>Logical, bitwise and conditional operations now work for integer data
520types.</li>
521<li>Function calls involving basic types work now.</li>
522<li>Support for integer arrays.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]523<li>Compiler can now emit libcalls for operations not support by m/c
524instructions.</li>
525<li>Support for both data and ROM address spaces.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]526</ul>
527
528<p>Things not yet supported:</p>
529
530<ul>
531<li>Floating point.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]532<li>Passing/returning aggregate types to and from functions.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]533<li>Variable arguments.</li>
534<li>Indirect function calls.</li>
Chris Lattner5f393542009-03-02 03:24:11 +0000[diff] [blame]535<li>Interrupts/programs.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]536<li>Debug info.</li>
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]537</ul>
538
539</div>
540
541
542<!--=========================================================================-->
543<div class="doc_subsection">
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]544<a name="llvmc">Improvements in LLVMC</a>
545</div>
546
547<div class="doc_text">
548<p>New features include:</p>
549
550<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]551<li>Beginning with LLVM 2.5, <tt>llvmc2</tt> is known as
552 just <tt>llvmc</tt>. The old <tt>llvmc</tt> driver was removed.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]553
554<li>The Clang plugin was substantially improved and is now enabled
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]555 by default. The command <tt>llvmc --clang</tt> can be now used as a
556 synonym to <tt>ccc</tt>.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]557
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]558<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]559 common errors like multiple default edges, mismatched output/input language
560 names and cycles. In general, these checks can't be done at compile-time
561 because of the need to support plugins.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]562
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]563<li>Plugins are now more flexible and can refer to compilation graph nodes and
564 options defined in other plugins. To manage dependencies, a priority-sorting
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]565 mechanism was introduced. This change affects the TableGen file syntax. See the
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]566 documentation for details.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]567
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]568<li>Hooks can now be provided with arguments. The syntax is "<tt>$CALL(MyHook,
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]569 'Arg1', 'Arg2', 'Arg3')</tt>".</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]570
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]571<li>A new option type: multi-valued option, for options that take more than one
572 argument (for example, "<tt>-foo a b c</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]573
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]574<li>New option properties: '<tt>one_or_more</tt>', '<tt>zero_or_more</tt>',
575'<tt>hidden</tt>' and '<tt>really_hidden</tt>'.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]576
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]577<li>The '<tt>case</tt>' expression gained an '<tt>error</tt>' action and
578 an '<tt>empty</tt>' test (equivalent to "<tt>(not (not_empty ...))</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]579
580<li>Documentation now looks more consistent to the rest of the LLVM
581 docs. There is also a man page now.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]582
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]583</ul>
584
585</div>
586
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]587
588<!--=========================================================================-->
589<div class="doc_subsection">
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]590<a name="changes">Major Changes and Removed Features</a>
591</div>
592
593<div class="doc_text">
594
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]595<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]596on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]597from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]598
599<ul>
600
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]601<li>llvm-gcc defaults to <tt>-fno-math-errno</tt> on all X86 targets.</li>
602
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]603</ul>
604
605
606<p>In addition, many APIs have changed in this release. Some of the major LLVM
607API changes are:</p>
608
609<ul>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]610<li>?</li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]611</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]612
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]613</div>
614
615
616
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]617<!-- *********************************************************************** -->
618<div class="doc_section">
619 <a name="portability">Portability and Supported Platforms</a>
620</div>
621<!-- *********************************************************************** -->
622
623<div class="doc_text">
624
625<p>LLVM is known to work on the following platforms:</p>
626
627<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]628<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]629Linux, Fedora Core and FreeBSD (and probably other unix-like systems).</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]630<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]631and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]632<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]633<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
634 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]635<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]636<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]637<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]638</ul>
639
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]640<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]641to the machine and operating system on which it is built. However, minor
642porting may be required to get LLVM to work on new platforms. We welcome your
643portability patches and reports of successful builds or error messages.</p>
644
645</div>
646
647<!-- *********************************************************************** -->
648<div class="doc_section">
649 <a name="knownproblems">Known Problems</a>
650</div>
651<!-- *********************************************************************** -->
652
653<div class="doc_text">
654
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]655<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]656listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]657href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
658there isn't already one.</p>
659
660</div>
661
662<!-- ======================================================================= -->
663<div class="doc_subsection">
664 <a name="experimental">Experimental features included with this release</a>
665</div>
666
667<div class="doc_text">
668
669<p>The following components of this LLVM release are either untested, known to
670be broken or unreliable, or are in early development. These components should
671not be relied on, and bugs should not be filed against them, but they may be
672useful 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]673components, please contact us on the <a
674href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]675
676<ul>
Gabor Greifaa53e562008-10-14 11:31:14 +0000[diff] [blame]677<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Bill Wendling9c7c4382009-03-02 07:54:14 +0000[diff] [blame^]678<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
679 supported value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]680</ul>
681
682</div>
683
684<!-- ======================================================================= -->
685<div class="doc_subsection">
686 <a name="x86-be">Known problems with the X86 back-end</a>
687</div>
688
689<div class="doc_text">
690
691<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]692 <li>The X86 backend does not yet support
693 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
694 floating point stack</a>. It supports the 'f' and 't' constraints, but not
695 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]696 <li>The X86 backend generates inefficient floating point code when configured
697 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]698 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]699 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
700 currently due
701 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]702 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
703 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]704 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame]705 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]706 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]707</ul>
708
709</div>
710
711<!-- ======================================================================= -->
712<div class="doc_subsection">
713 <a name="ppc-be">Known problems with the PowerPC back-end</a>
714</div>
715
716<div class="doc_text">
717
718<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]719<li>The Linux PPC32/ABI support needs testing for the interpreter and static
720compilation, and lacks support for debug information.</li>
721</ul>
722
723</div>
724
725<!-- ======================================================================= -->
726<div class="doc_subsection">
727 <a name="arm-be">Known problems with the ARM back-end</a>
728</div>
729
730<div class="doc_text">
731
732<ul>
733<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]734processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]735results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
736<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
737</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]738<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
739 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]740programs compiled with LLVM. Please use more recent versions of QEMU.</li>
741</ul>
742
743</div>
744
745<!-- ======================================================================= -->
746<div class="doc_subsection">
747 <a name="sparc-be">Known problems with the SPARC back-end</a>
748</div>
749
750<div class="doc_text">
751
752<ul>
753<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
754 support the 64-bit SPARC ABI (-m64).</li>
755</ul>
756
757</div>
758
759<!-- ======================================================================= -->
760<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]761 <a name="mips-be">Known problems with the MIPS back-end</a>
762</div>
763
764<div class="doc_text">
765
766<ul>
767<li>The O32 ABI is not fully supported.</li>
768<li>64-bit MIPS targets are not supported yet.</li>
769</ul>
770
771</div>
772
773<!-- ======================================================================= -->
774<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]775 <a name="alpha-be">Known problems with the Alpha back-end</a>
776</div>
777
778<div class="doc_text">
779
780<ul>
781
782<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
783appropriate nops inserted to ensure restartability.</li>
784
785</ul>
786</div>
787
788<!-- ======================================================================= -->
789<div class="doc_subsection">
790 <a name="ia64-be">Known problems with the IA64 back-end</a>
791</div>
792
793<div class="doc_text">
794
795<ul>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]796<li>The Itanium backend is highly experimental, and has a number of known
797 issues. We are looking for a maintainer for the Itanium backend. If you
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]798 are interested, please contact the LLVMdev mailing list.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]799</ul>
800
801</div>
802
803<!-- ======================================================================= -->
804<div class="doc_subsection">
805 <a name="c-be">Known problems with the C back-end</a>
806</div>
807
808<div class="doc_text">
809
810<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]811<li><a href="http://llvm.org/PR802">The C backend has only basic support for
812 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]813<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
814 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]815 C++ code compiled with llc or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]816<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]817<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]818</ul>
819
820</div>
821
822
823<!-- ======================================================================= -->
824<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]825 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]826</div>
827
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]828<div class="doc_text">
829
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]830<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
831Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]832LLVMdev mailing list if you are interested.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]833
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]834<p>The only major language feature of GCC not supported by llvm-gcc is
835 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
836 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]837 supported on some targets (these are used when you take the address of a
838 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]839
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]840<p>If you run into GCC extensions which are not supported, please let us know.
841</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]842
843</div>
844
845<!-- ======================================================================= -->
846<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]847 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]848</div>
849
850<div class="doc_text">
851
852<p>The C++ front-end is considered to be fully
853tested and works for a number of non-trivial programs, including LLVM
854itself, Qt, Mozilla, etc.</p>
855
856<ul>
Anton Korobeynikovd9a17932008-10-11 18:27:16 +0000[diff] [blame]857<li>Exception handling works well on the X86 and PowerPC targets. Currently
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]858 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]859</ul>
860
861</div>
862
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]863<!-- ======================================================================= -->
864<div class="doc_subsection">
865 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
866</div>
867
868<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]869<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]870<li>Fortran support generally works, but there are still several unresolved bugs
871 in Bugzilla. Please see the tools/gfortran component for details.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]872
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]873<li>The Fortran front-end currently does not build on Darwin (without tweaks)
874 due to unresolved dependencies on the C front-end.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]875</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]876</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]877
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]878<!-- ======================================================================= -->
879<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]880 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]881</div>
882
883<div class="doc_text">
884The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
885technology and problems should be expected.
886<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]887<li>The Ada front-end currently only builds on X86-32. This is mainly due
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]888to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]889however 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]890which does support trampolines.</li>
891<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]892This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
893exception handling, which is used internally by the compiler.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]894Workaround: configure with --disable-bootstrap.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]895<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
896and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]897(c380004 also fails with gcc-4.2 mainline).
898If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
899causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]900<li>Some gcc specific Ada tests continue to crash the compiler.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]901<li>The -E binder option (exception backtraces)
902<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
903crashing if an exception is raised. Workaround: do not use -E.</li>
904<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
905or finish at a non-byte offset</a> in a record. Workaround: do not pack records
906or use representation clauses that result in a field of a non-discrete type
907starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]908<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
909'main' as generated by the Ada binder to be invalid</a>.
910Workaround: hand edit the file to use pointers for <tt>argv</tt> and
911<tt>envp</tt> rather than integers.</li>
912<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
913ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]914</ul>
915</div>
916
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]917<!-- *********************************************************************** -->
918<div class="doc_section">
919 <a name="additionalinfo">Additional Information</a>
920</div>
921<!-- *********************************************************************** -->
922
923<div class="doc_text">
924
925<p>A wide variety of additional information is available on the <a
926href="http://llvm.org">LLVM web page</a>, in particular in the <a
927href="http://llvm.org/docs/">documentation</a> section. The web page also
928contains versions of the API documentation which is up-to-date with the
929Subversion version of the source code.
930You can access versions of these documents specific to this release by going
931into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
932
933<p>If you have any questions or comments about LLVM, please feel free to contact
934us via the <a href="http://llvm.org/docs/#maillist"> mailing
935lists</a>.</p>
936
937</div>
938
939<!-- *********************************************************************** -->
940
941<hr>
942<address>
943 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]945 <a href="http://validator.w3.org/check/referer"><img
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]947
948 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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