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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 47202c307329c503138e7c3f57fef460aa29fcf3 / . / 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
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]84repository (which roughly includes the LLVM optimizers, code generators and
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]85supporting tools) and the llvm-gcc repository. In addition to this code, the
86LLVM Project includes other sub-projects that are in development. The two which
Chris Lattner2c3ef982008-10-11 18:18:28 +0000[diff] [blame]87are the most actively developed are the <a href="#clang">Clang Project</a> and
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]88the <a href="#vmkit">VMKit Project</a>.
Chris Lattnerf6a0d382008-06-08 21:58:17 +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
102a set of new 'LLVM native' front-end technologies for the LLVM optimizer
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]103and code generator. While Clang is not included in the LLVM 2.5 release, it
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]104is continuing to make major strides forward in all areas. Its C and Objective-C
105parsing and code generation support is now very solid. For example, it is
106capable of successfully building many real applications for X86-32 and X86-64,
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]107including <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">the FreeBSD
108kernel</a>. C++ is also making <a
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]109href="http://clang.llvm.org/cxx_status.html">incredible progress</a>, and work
110on templates has recently started.</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]111
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]112<p>While Clang is not yet production quality, it is progressing very nicely and
113is quite usable for building many C and Objective-C applications. If you are
114interested in fast compiles and good diagnostics, we encourage you to try it out
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]115by <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]116and reporting any issues you hit to the <a
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]117href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
118list</a>.</p>
119
120<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]121
Daniel Dunbarf3e35782008-10-14 23:25:09 +0000[diff] [blame]122<ul>
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]123<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]124 interface.</li>
125<li>The X86-64 ABI is now supported.</li>
126<li>Precompiled header support is now implemented.</li>
Chris Lattnerc97507b2009-02-25 05:09:54 +0000[diff] [blame]127<li>Objective-C support is significantly improved beyond LLVM 2.4, supporting
128 many features, such as Objective-C Garbage Collection.</li>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]129<li>Many many bugs are fixed and many features have been added.</li>
Chris Lattnera3c683b2008-10-13 18:11:54 +0000[diff] [blame]130</div>
131
132<!--=========================================================================-->
133<div class="doc_subsection">
134<a name="clangsa">Clang Static Analyzer</a>
135</div>
136
137<div class="doc_text">
138
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]139<p>Previously announced in the last LLVM release, the Clang project also
140includes an early stage static source code analysis tool for <a
141href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
142in C and Objective-C programs. The tool performs a growing set of checks to find
143bugs that occur on a specific path within a program.</p>
Chris Lattnerc2d84672008-10-14 00:52:49 +0000[diff] [blame]144
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]145<p>In the LLVM 2.5 time-frame there have been many significant improvements to
146the analyzer's core path simulation engine and machinery for generating
147path-based bug reports to end-users. Particularly noteworthy improvements
148include experimental support for full field-sensitivity and reasoning about heap
149objects as well as an improved value-constraints subengine that does a much
150better job of reasoning about inequality relationships (e.g., <tt>x &gt; 2</tt>)
151between variables and constants.
Ted Kremenek0437b2c2008-10-14 05:14:21 +0000[diff] [blame]152
Ted Kremeneka0d77d72009-02-27 07:01:32 +0000[diff] [blame]153<p>The set of checks performed by the static analyzer continue to expand, and
154future plans for the tool include full source-level inter-procedural analysis
155and deeper checks such as buffer overrun detection. There are many opportunities
156to extend and enhance the static analyzer, and anyone interested in working on
157this project is encouraged to get involved!</p>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]158
159</div>
160
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]161<!--=========================================================================-->
162<div class="doc_subsection">
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]163<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]164</div>
165
166<div class="doc_text">
167<p>
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]168The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]169a JVM and a CLI Virtual Machines (Microsoft .NET is an
170implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
171
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]172<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]173<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
174bug fixes, cleanup and new features. The major changes are:</p>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]175
Nicolas Geoffray2b139382008-10-14 19:23:04 +0000[diff] [blame]176<ul>
177
Chris Lattner47bcf612009-02-26 05:20:36 +0000[diff] [blame]178<li>Ahead of Time compiler: compiles .class files to llvm .bc. VMKit uses this
179functionality to native compile the standard classes (eg java.lang.String).
180Users can compile AOT .class files into dynamic libraries and run them with the
181help of VMKit.</li>
182
183<li>New exception model: the dwarf exception model is very slow for
184exception-intensive applications, so the JVM has had a new implementation of
185exceptions which check at each function call if an exception happened. There is
186a low performance penalty on applications without exceptions, but it is a big
187gain for exception-intensive applications. For example the jack benchmark in
188Spec JVM98 is 6x faster (performance gain of 83%).</li>
189
190<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]191
192</ul>
Chris Lattner78a130b2008-10-13 18:01:01 +0000[diff] [blame]193</div>
194
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]195<!-- *********************************************************************** -->
196<div class="doc_section">
197 <a name="externalproj">External Projects Using LLVM 2.5</a>
198</div>
199<!-- *********************************************************************** -->
200
201<!--=========================================================================-->
202<div class="doc_subsection">
203<a name="pure">Pure</a>
204</div>
205
206<div class="doc_text">
207<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]208<a href="http://pure-lang.googlecode.com/">Pure</a>
209is an algebraic/functional programming language based on term rewriting.
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]210Programs are collections of equations which are used to evaluate expressions in
211a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]212lexical closures, a hygienic macro system (also based on term rewriting),
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]213built-in list and matrix support (including list and matrix comprehensions) and
214an easy-to-use C interface. The interpreter uses LLVM as a backend to
215 JIT-compile Pure programs to fast native code.</p>
216
217<p>In addition to the usual algebraic data structures, Pure also has
218MATLAB-style matrices in order to support numeric computations and signal
219processing in an efficient way. Pure is mainly aimed at mathematical
220applications right now, but it has been designed as a general purpose language.
221The dynamic interpreter environment and the C interface make it possible to use
222it as a kind of functional scripting language for many application areas.
223</p>
224</div>
225
226
227<!--=========================================================================-->
228<div class="doc_subsection">
229<a name="ldc">LLVM D Compiler</a>
230</div>
231
232<div class="doc_text">
233<p>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]234<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
235the D Programming Language using the LLVM optimizer and code generator.
236LDC project works great with the LLVM 2.5 release. General improvmenets in this
237cycle have included new inline asm constraint handling, better debug info
238support, general bugfixes, and better x86-64 support. This has allowed
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]239some major improvements in LDC, getting us much closer to being as
240fully featured as the original DMD compiler from DigitalMars.
241</p>
242</div>
243
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]244<!--=========================================================================-->
245<div class="doc_subsection">
246<a name="RoadsendPHP">Roadsend PHP</a>
247</div>
248
249<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]250<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
251source compiler for the PHP programming language that uses LLVM for its
252optimizer, JIT, and static compiler. This is a reimplementation of an earlier
253project that is now based on the LLVM.</p>
Chris Lattner1ad599a2009-02-28 18:58:01 +0000[diff] [blame]254</div>
Chris Lattnerb2cc5022009-02-26 22:33:38 +0000[diff] [blame]255
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]256
257<!-- *********************************************************************** -->
258<div class="doc_section">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]259 <a name="whatsnew">What's New in LLVM 2.5?</a>
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]260</div>
261<!-- *********************************************************************** -->
262
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]263<div class="doc_text">
264
Bill Wendling385b0d32008-10-27 09:27:33 +0000[diff] [blame]265<p>This release includes a huge number of bug fixes, performance tweaks, and
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]266minor improvements. Some of the major improvements and new features are listed
267in this section.
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]268</p>
269</div>
270
Chris Lattnerf6a0d382008-06-08 21:58:17 +0000[diff] [blame]271<!--=========================================================================-->
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]272<div class="doc_subsection">
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]273<a name="majorfeatures">Major New Features</a>
274</div>
275
276<div class="doc_text">
277
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]278<p>LLVM 2.5 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]279
280<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]281<li>LLVM 2.5 includes a brand new <a
282href="http://en.wikipedia.org/wiki/XCore">XCore</a> backend.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]283
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]284<li>llvm-gcc now generally supports the GFortan front-end, and the precompiled
285release binaries now support Fortran, even on Mac OS/X.</li>
Chris Lattnera53f4972009-02-25 06:34:50 +0000[diff] [blame]286
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]287<li>CMake is now used by the <a href="GettingStartedVS.html">LLVM build process
288on Windows</a>. It automatically generates Visual Studio project files (and
289more) from a set of simple text files. This makes it much easier to
290maintain. In time, we'd like to standardize on CMake for everything.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]291
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]292<li>LLVM 2.5 now uses (and includes) Google Test for unit testing.</li>
Chris Lattner5c109932009-02-26 07:29:17 +0000[diff] [blame]293
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]294<li>The LLVM native code generator now supports arbitrary precision integers.
295Types like <tt>i33</tt> have long been valid in the LLVM IR, but were previously
296only supported by the interpreter. Note that the C backend still does not
297support these.</li>
Chris Lattner56b64702009-02-25 07:32:53 +0000[diff] [blame]298
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]299<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]300</ul>
301
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]302</div>
303
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]304
305<!--=========================================================================-->
306<div class="doc_subsection">
Chris Lattnerf65224f2008-06-08 21:34:41 +0000[diff] [blame]307<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]308</div>
309
310<div class="doc_text">
311
Chris Lattner4352cc82008-10-13 20:47:20 +0000[diff] [blame]312<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
313front-ends and driver with the LLVM optimizer and code generator. It currently
314includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]315
Chris Lattner5cce7a52008-06-08 22:59:35 +0000[diff] [blame]316<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]317<li>In this release, the GCC inliner is completely disabled. Previously the GCC
318inliner was used to handle always-inline functions and other cases. This caused
319problems with code size growth, and it is completely disabled in this
320release.</li>
321
322<li>llvm-gcc (and LLVM in general) now support code generation for stack
323canaries, which is an effective form of <a
324href="http://en.wikipedia.org/wiki/Stack-smashing_protection">buffer overflow
325protection</a>. llvm-gcc supports this with the <tt>-fstack-protector</tt>
326command line option (just like GCC). In LLVM IR, you can request code
327generation for stack canaries with function attributes.
328</li>
Gabor Greif0e49cc82008-06-09 06:06:18 +0000[diff] [blame]329</ul>
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]330
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]331</div>
332
333
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]334<!--=========================================================================-->
335<div class="doc_subsection">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]336<a name="coreimprovements">LLVM IR and Core Improvements</a>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]337</div>
338
339<div class="doc_text">
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]340<p>LLVM IR has several new features that are used by our existing front-ends and
341can be useful if you are writing a front-end for LLVM:</p>
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]342
Chris Lattnerc5a4e312008-06-05 06:25:56 +0000[diff] [blame]343<ul>
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]344<li>The <a href="LangRef.html#i_shufflevector">shufflevector</a> instruction
345has been generalized to allow different shuffle mask width than its input
346vectors. This allows you to use shufflevector to combine two
347"&lt;4 x float&gt;" vectors into a "&lt;8 x float&gt;" for example.</li>
348
349<li>LLVM IR now supports new intrinsics for computing and acting on <a
350href="LangRef.html#int_overflow">overflow of integer operations</a>. This allows
351efficient code generation for languages that must trap or throw an exception on
352overflow. While these intrinsics work on all targets, they only generate
353efficient code on X86 so far.</li>
354
355<li>LLVM IR now supports a new <a href="LangRef.html#linkage">private
356linkage</a> type to produce labels that are stripped by the assembler before it
357produces a .o file (thus they are invisible to the linker).</li>
358
359<li>LLVM IR supports two new attributes for better alias analysis. The <a
360href="LangRef.html#paramattrs">noalias</a> attribute can now be used on the
361return value of a function to indicate that it returns new memory (e.g.
362'malloc', 'calloc', etc).</li>
363
364<li>The new <a href="LangRef.html#paramattrs">nocapture</a> attribute can be
365used on pointer arguments to functions that access through but do not return the
366pointer in a data structure that out lives the call (e.g. 'strlen', 'memcpy',
367and many others). The simplifylibcalls pass applies these attributes to
368standard libc functions.</li>
369
370<li>The parser for ".ll" files in lib/AsmParser is now completely rewritten as a
371recursive descent parser. This parser produces better error messages (including
372caret diagnostics) is less fragile (less likely to crash on strange things) does
373not leak memory, is more efficient, and eliminates LLVM's last use of the
374'bison' tool.</li>
375
376<li>Debug information representation and manipulation internals have been
377 consolidated to use a new set of classes in
378 <tt>llvm/Analysis/DebugInfo.h</tt> classes. These routines are more
379 efficient, robust, and extensible and replace the older mechanisms.
380 llvm-gcc, clang, and the code generator now use them to create and process
381 debug information.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]382
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]383</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]384
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]385</div>
386
387<!--=========================================================================-->
388<div class="doc_subsection">
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]389<a name="optimizer">Optimizer Improvements</a>
390</div>
391
392<div class="doc_text">
393
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]394<p>In addition to a huge array of bug fixes and minor performance tweaks, this
395release includes a few major enhancements and additions to the optimizers:</p>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame]396
397<ul>
398
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]399<li>The loop optimizer now improves floating point induction variables in
400several ways, including adding shadow induction variables to avoid
401"integer &lt;-&gt; floating point" conversions in loops when safe.</li>
402
403<li>The "-mem2reg" pass is now much faster on code with huge basic blocks.</li>
404
405<li>The "-jump-threading" pass is more powerful: it is iterative
406 and handles threading based on values with fully and partially redundant
407 loads.</li>
408
409<li>The "-memdep" memory dependence analysis pass (used by GVN and memcpyopt) is
410 both faster and more aggressive.</li>
411
412<li>The "-scalarrepl" scalar replacement of aggregates pass is more aggressive
413 about promoting unions to registers.</li>
414</li>
Chris Lattnerea9c2242008-10-13 21:50:36 +0000[diff] [blame]415
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]416</ul>
417
418</div>
419
420<!--=========================================================================-->
421<div class="doc_subsection">
422<a name="codegen">Code Generator Improvements</a>
423</div>
424
425<div class="doc_text">
426
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]427<p>We have put a significant amount of work into the code generator
428infrastructure, which allows us to implement more aggressive algorithms and make
429it run faster:</p>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]430
431<ul>
Duncan Sands335d5e42009-02-25 11:50:08 +0000[diff] [blame]432<li>The type legalization logic has been completely rewritten, and is now
433more powerful (it supports arbitrary precision integer types for example)
434and hopefully more correct.
435The type legalizer converts operations on types that are not natively
436supported by the target machine into equivalent code sequences that only use
437natively supported types.
438The old type legalizer is still available and will be used if
439<tt>-disable-legalize-types</tt> is passed to <tt>llc</tt>.
440</li>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]441<li>?</li>
Chris Lattner0eef6e42008-06-08 02:45:07 +0000[diff] [blame]442
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]443
444how to write a backend doc docs/WritingAnLLVMBackend.html
445asmprinters seperate from targets for jits
446fastisel + exception handling
447vector widening <3 x float> -> <4 x float>
448PBQP register allocator now supports register coalescing.
449
450
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]451</ul>
452
453</div>
454
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]455<!--=========================================================================-->
456<div class="doc_subsection">
457<a name="x86">X86-32 and X86-64 Target Improvements</a>
458</div>
459
460<div class="doc_text">
461<p>New features of the X86 target include:
462</p>
463
464<ul>
465non-zero __builtin_return_address values on X86.
466vector shift support + X86 backend.
467x86 JIT now detects core i7 and atom, autoconfiguring itself appropriately.
468x86-64 now uses red zone (unless -mno-red-zone option is specified).
469x86 backend GS segment -> addr space 256 (r62980)
470X86 backend now supports -disable-mmx.
471JIT supports exceptions on linux/x86-64 and linux/x86-64.
472JIT TLS support on x86-32 but not x86-64.
473</ul>
474
475
476</div>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]477
478<!--=========================================================================-->
479<div class="doc_subsection">
Chris Lattnere1fbd752009-02-26 07:32:11 +0000[diff] [blame]480<a name="pic16">PIC16 Target Improvements</a>
481</div>
482
483<div class="doc_text">
484<p>New features of the PIC16 target include:
485</p>
486
487<ul>
488<li>Both direct and indirect load/stores work now.</li>
489<li>Logical, bitwise and conditional operations now work for integer data
490types.</li>
491<li>Function calls involving basic types work now.</li>
492<li>Support for integer arrays.</li>
493<li>Compiler can now emit libcalls for operations not support by m/c insns.</li>
494<li>Support for both data and rom address spaces.</li>
495</li>
496</ul>
497
498<p>Things not yet supported:</p>
499
500<ul>
501<li>Floating point.</li>
502<li>Passing/returning aggregate types to/from functions.</li>
503<li>Variable arguments.</li>
504<li>Indirect function calls.</li>
505<li>Interrupts/prgrams.</li>
506<li>Debug info.</li>
507</li>
508</ul>
509
510</div>
511
512
513<!--=========================================================================-->
514<div class="doc_subsection">
515<a name="othertargetspecific">Other Target Specific Improvements</a>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]516</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]517
518<div class="doc_text">
Chris Lattnerc3649452008-02-10 08:17:19 +0000[diff] [blame]519<p>New target-specific features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]520</p>
521
522<ul>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]523<li>?</li>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]524</ul>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]525
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]526</div>
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]527
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]528<!--=========================================================================-->
529<div class="doc_subsection">
530<a name="llvmc">Improvements in LLVMC</a>
531</div>
532
533<div class="doc_text">
534<p>New features include:</p>
535
536<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]537<li>Beginning with LLVM 2.5, <tt>llvmc2</tt> is known as
538 just <tt>llvmc</tt>. The old <tt>llvmc</tt> driver was removed.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]539
540<li>The Clang plugin was substantially improved and is now enabled
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]541 by default. The command <tt>llvmc --clang</tt> can be now used as a
542 synonym to <tt>ccc</tt>.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]543
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]544<li>There is now a <tt>--check-graph</tt> option which is supposed to catch
545 common errors like multiple default edges, mismatched output/input language
546 names and cycles. In general, these checks can't be done at compile-time
547 because of the need to support plugins.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]548
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]549<li>Plugins are now more flexible and can refer to compilation graph nodes and
550 options defined in other plugins. To manage dependencies, a priority-sorting
551 mechanism was introduced. This change affects the TableGen file syntax; see the
552 documentation for details.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]553
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]554<li>Hooks can now be provided with arguments. The syntax is "<tt>$CALL(MyHook,
555 'Arg1', 'Arg2', 'Arg #3')</tt>".</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]556
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]557<li>A new option type: multi-valued option, for options that take more than one
558 argument (for example, "<tt>-foo a b c</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]559
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]560<li>New option properties: '<tt>one_or_more</tt>', '<tt>zero_or_more</tt>',
561'<tt>hidden</tt>' and '<tt>really_hidden</tt>'.</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]562
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]563<li>The '<tt>case</tt>' expression gained an '<tt>error</tt>' action and
564 an '<tt>empty</tt>' test (equivalent to "<tt>(not (not_empty ...))</tt>").</li>
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]565
566<li>Documentation now looks more consistent to the rest of the LLVM
567 docs. There is also a man page now.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]568
Chris Lattner7ccc40d2009-03-01 02:30:21 +0000[diff] [blame]569</ul>
570
571</div>
572
Chris Lattnere45f18b2008-06-05 08:02:49 +0000[diff] [blame]573
574<!--=========================================================================-->
575<div class="doc_subsection">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]576<a name="otherimprovements">Other Improvements</a>
577</div>
578
579<div class="doc_text">
580<p>New features include:
581</p>
582
583<ul>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]584<li>?</li>
Tanya Lattnerc79f7542008-11-04 18:40:27 +0000[diff] [blame]585
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]586</ul>
Mikhail Glushenkov808cd3e2008-10-13 02:08:34 +0000[diff] [blame]587
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]588</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]589
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]590<!--=========================================================================-->
591<div class="doc_subsection">
592<a name="changes">Major Changes and Removed Features</a>
593</div>
594
595<div class="doc_text">
596
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]597<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]598on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]599from the previous release.</p>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]600
601<ul>
602
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]603<li>llvm-gcc defaults to -fno-math-errno on all x86 targets.</li>
Chris Lattnercc64a322008-10-13 22:06:31 +0000[diff] [blame]604</ul>
605
606
607<p>In addition, many APIs have changed in this release. Some of the major LLVM
608API changes are:</p>
609
610<ul>
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]611<li>?</li>
Devang Patel0e3da1a2008-10-14 20:03:43 +0000[diff] [blame]612</ul>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]613
Chris Lattner95d25072009-02-25 04:41:31 +0000[diff] [blame]614<li>?</li>
Chris Lattner92eacf82008-10-13 17:57:36 +0000[diff] [blame]615</ul>
616
617</div>
618
619
620
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]621<!-- *********************************************************************** -->
622<div class="doc_section">
623 <a name="portability">Portability and Supported Platforms</a>
624</div>
625<!-- *********************************************************************** -->
626
627<div class="doc_text">
628
629<p>LLVM is known to work on the following platforms:</p>
630
631<ul>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]632<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]633Linux, Fedora Core and FreeBSD (and probably other unix-like systems).</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]634<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]635and 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]636<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]637<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
638 support is available for native builds with Visual C++).</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]639<li>Sun UltraSPARC workstations running Solaris 10.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]640<li>Alpha-based machines running Debian GNU/Linux.</li>
Gabor Greif5e75e652008-06-05 18:39:01 +0000[diff] [blame]641<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]642</ul>
643
Chris Lattnerba948522008-06-05 06:57:39 +0000[diff] [blame]644<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]645to the machine and operating system on which it is built. However, minor
646porting may be required to get LLVM to work on new platforms. We welcome your
647portability patches and reports of successful builds or error messages.</p>
648
649</div>
650
651<!-- *********************************************************************** -->
652<div class="doc_section">
653 <a name="knownproblems">Known Problems</a>
654</div>
655<!-- *********************************************************************** -->
656
657<div class="doc_text">
658
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]659<p>This section contains significant known problems with the LLVM system,
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]660listed by component. If you run into a problem, please check the <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]661href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
662there isn't already one.</p>
663
664</div>
665
666<!-- ======================================================================= -->
667<div class="doc_subsection">
668 <a name="experimental">Experimental features included with this release</a>
669</div>
670
671<div class="doc_text">
672
673<p>The following components of this LLVM release are either untested, known to
674be broken or unreliable, or are in early development. These components should
675not be relied on, and bugs should not be filed against them, but they may be
676useful 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]677components, please contact us on the <a
678href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]679
680<ul>
Gabor Greifaa53e562008-10-14 11:31:14 +0000[diff] [blame]681<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]682<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]683 value for this option.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]684</ul>
685
686</div>
687
688<!-- ======================================================================= -->
689<div class="doc_subsection">
690 <a name="x86-be">Known problems with the X86 back-end</a>
691</div>
692
693<div class="doc_text">
694
695<ul>
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]696 <li>The X86 backend does not yet support
697 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
698 floating point stack</a>. It supports the 'f' and 't' constraints, but not
699 'u'.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]700 <li>The X86 backend generates inefficient floating point code when configured
701 to generate code for systems that don't have SSE2.</li>
Duncan Sands8b4f3772008-06-08 19:38:43 +0000[diff] [blame]702 <li>Win64 code generation wasn't widely tested. Everything should work, but we
Anton Korobeynikov77d15e22008-06-08 10:24:13 +0000[diff] [blame]703 expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
704 currently due
705 to <a href="http://llvm.org/PR2255">several</a>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]706 <a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
707 'u' inline assembly constraint and X87 floating point inline assembly.</li>
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]708 <li>The X86-64 backend does not yet support the LLVM IR instruction
Chris Lattner47202c32009-03-02 02:37:32 +0000[diff] [blame^]709 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
Dan Gohman3882ecb2008-06-08 23:05:11 +0000[diff] [blame]710 argument constructs on X86-64 by lowering them manually.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]711</ul>
712
713</div>
714
715<!-- ======================================================================= -->
716<div class="doc_subsection">
717 <a name="ppc-be">Known problems with the PowerPC back-end</a>
718</div>
719
720<div class="doc_text">
721
722<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]723<li>The Linux PPC32/ABI support needs testing for the interpreter and static
724compilation, and lacks support for debug information.</li>
725</ul>
726
727</div>
728
729<!-- ======================================================================= -->
730<div class="doc_subsection">
731 <a name="arm-be">Known problems with the ARM back-end</a>
732</div>
733
734<div class="doc_text">
735
736<ul>
737<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]738processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]739results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
740<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
741</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]742<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
743 execute
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]744programs compiled with LLVM. Please use more recent versions of QEMU.</li>
745</ul>
746
747</div>
748
749<!-- ======================================================================= -->
750<div class="doc_subsection">
751 <a name="sparc-be">Known problems with the SPARC back-end</a>
752</div>
753
754<div class="doc_text">
755
756<ul>
757<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
758 support the 64-bit SPARC ABI (-m64).</li>
759</ul>
760
761</div>
762
763<!-- ======================================================================= -->
764<div class="doc_subsection">
Bruno Cardoso Lopes62d45d72008-10-25 14:56:26 +0000[diff] [blame]765 <a name="mips-be">Known problems with the MIPS back-end</a>
766</div>
767
768<div class="doc_text">
769
770<ul>
771<li>The O32 ABI is not fully supported.</li>
772<li>64-bit MIPS targets are not supported yet.</li>
773</ul>
774
775</div>
776
777<!-- ======================================================================= -->
778<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]779 <a name="alpha-be">Known problems with the Alpha back-end</a>
780</div>
781
782<div class="doc_text">
783
784<ul>
785
786<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
787appropriate nops inserted to ensure restartability.</li>
788
789</ul>
790</div>
791
792<!-- ======================================================================= -->
793<div class="doc_subsection">
794 <a name="ia64-be">Known problems with the IA64 back-end</a>
795</div>
796
797<div class="doc_text">
798
799<ul>
Chris Lattnerf06141a2008-06-08 23:12:47 +0000[diff] [blame]800<li>The Itanium backend is highly experimental, and has a number of known
801 issues. We are looking for a maintainer for the Itanium backend. If you
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]802 are interested, please contact the LLVMdev mailing list.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]803</ul>
804
805</div>
806
807<!-- ======================================================================= -->
808<div class="doc_subsection">
809 <a name="c-be">Known problems with the C back-end</a>
810</div>
811
812<div class="doc_text">
813
814<ul>
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]815<li><a href="http://llvm.org/PR802">The C backend has only basic support for
816 inline assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]817<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
818 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]819 C++ code compiled with llc or native compilers.</li>
Duncan Sandsbd0ad6e2008-02-10 13:40:55 +0000[diff] [blame]820<li>The C backend does not support all exception handling constructs.</li>
Duncan Sandse6e264c2009-02-25 11:51:54 +0000[diff] [blame]821<li>The C backend does not support arbitrary precision integers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]822</ul>
823
824</div>
825
826
827<!-- ======================================================================= -->
828<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]829 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]830</div>
831
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]832<div class="doc_text">
833
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]834<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
835Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Gabor Greif45fc8b12008-10-15 10:47:24 +0000[diff] [blame]836LLVMdev mailing list if you are interested.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]837
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]838<p>The only major language feature of GCC not supported by llvm-gcc is
839 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
840 are only supported on some targets. For example, trampolines are only
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]841 supported on some targets (these are used when you take the address of a
842 nested function).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]843
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]844<p>If you run into GCC extensions which are not supported, please let us know.
845</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]846
847</div>
848
849<!-- ======================================================================= -->
850<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]851 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]852</div>
853
854<div class="doc_text">
855
856<p>The C++ front-end is considered to be fully
857tested and works for a number of non-trivial programs, including LLVM
858itself, Qt, Mozilla, etc.</p>
859
860<ul>
Anton Korobeynikovd9a17932008-10-11 18:27:16 +0000[diff] [blame]861<li>Exception handling works well on the X86 and PowerPC targets. Currently
Chris Lattnerb1ad47c2008-11-10 05:40:34 +0000[diff] [blame]862 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]863</ul>
864
865</div>
866
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]867<!-- ======================================================================= -->
868<div class="doc_subsection">
869 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
870</div>
871
872<div class="doc_text">
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]873<ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]874<li>Fortran support generally works, but there are still several unresolved bugs
875 in Bugzilla. Please see the tools/gfortran component for details.</li>
Mikhail Glushenkovf61066a2009-03-01 18:09:47 +0000[diff] [blame]876
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]877<li>The Fortran front-end currently does not build on Darwin (without tweaks)
878 due to unresolved dependencies on the C front-end.</li>
Gabor Greif1fc8fbc2008-11-04 21:50:59 +0000[diff] [blame]879</ul>
Chris Lattner6c8a1b82008-10-30 03:58:13 +0000[diff] [blame]880</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]881
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]882<!-- ======================================================================= -->
883<div class="doc_subsection">
Chris Lattner499c07c2008-06-05 06:35:40 +0000[diff] [blame]884 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]885</div>
886
887<div class="doc_text">
888The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
889technology and problems should be expected.
890<ul>
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]891<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]892to lack of trampoline support (pointers to nested functions) on other platforms,
Duncan Sandsa73561c2008-06-08 20:18:35 +0000[diff] [blame]893however 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]894which does support trampolines.</li>
895<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]896This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
897exception handling, which is used internally by the compiler.
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]898Workaround: configure with --disable-bootstrap.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]899<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
900and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
Duncan Sandsf73473e2009-02-25 11:59:06 +0000[diff] [blame]901(c380004 also fails with gcc-4.2 mainline).
902If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
903causes the compiler to go into an infinite loop, using up all system memory.</li>
Duncan Sands2dbc2e82008-10-13 17:27:23 +0000[diff] [blame]904<li>Some gcc specific Ada tests continue to crash the compiler.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]905<li>The -E binder option (exception backtraces)
906<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
907crashing if an exception is raised. Workaround: do not use -E.</li>
908<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
909or finish at a non-byte offset</a> in a record. Workaround: do not pack records
910or use representation clauses that result in a field of a non-discrete type
911starting or finishing in the middle of a byte.</li>
Chris Lattnerd95b5962008-06-08 21:19:07 +0000[diff] [blame]912<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
913'main' as generated by the Ada binder to be invalid</a>.
914Workaround: hand edit the file to use pointers for <tt>argv</tt> and
915<tt>envp</tt> rather than integers.</li>
916<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
917ignored</a>.</li>
Chris Lattnerdaeb3232008-02-12 06:29:45 +0000[diff] [blame]918</ul>
919</div>
920
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]921<!-- *********************************************************************** -->
922<div class="doc_section">
923 <a name="additionalinfo">Additional Information</a>
924</div>
925<!-- *********************************************************************** -->
926
927<div class="doc_text">
928
929<p>A wide variety of additional information is available on the <a
930href="http://llvm.org">LLVM web page</a>, in particular in the <a
931href="http://llvm.org/docs/">documentation</a> section. The web page also
932contains versions of the API documentation which is up-to-date with the
933Subversion version of the source code.
934You can access versions of these documents specific to this release by going
935into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
936
937<p>If you have any questions or comments about LLVM, please feel free to contact
938us via the <a href="http://llvm.org/docs/#maillist"> mailing
939lists</a>.</p>
940
941</div>
942
943<!-- *********************************************************************** -->
944
945<hr>
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