Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / ccedda4f3460575743ed25a090ee3904d971ab5a / . / docs / ReleaseNotes-2.6.html
blob: 25be8602cdc8a6270b05e9c042431e1257d87df9 [file] [log] [blame]
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7 <title>LLVM 2.6 Release Notes</title>
8</head>
9<body>
10
11<div class="doc_title">LLVM 2.6 Release Notes</div>
12
13<ol>
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#subproj">Sub-project Status Update</a></li>
16 <li><a href="#externalproj">External Projects Using LLVM 2.6</a></li>
17 <li><a href="#whatsnew">What's New in LLVM 2.6?</a></li>
18 <li><a href="GettingStarted.html">Installation Instructions</a></li>
19 <li><a href="#portability">Portability and Supported Platforms</a></li>
20 <li><a href="#knownproblems">Known Problems</a></li>
21 <li><a href="#additionalinfo">Additional Information</a></li>
22</ol>
23
24<div class="doc_author">
25 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
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
36<p>This document contains the release notes for the LLVM Compiler
37Infrastructure, release 2.6. Here we describe the status of LLVM, including
38major improvements from the previous release and significant known problems.
39All LLVM releases may be downloaded from the <a
40href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
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
45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
46List</a> is a good place to send them.</p>
47
48<p>Note that if you are reading this file from a Subversion checkout or the
49main LLVM web page, this document applies to the <i>next</i> release, not the
50current one. To see the release notes for a specific release, please see the
51<a href="http://llvm.org/releases/">releases page</a>.</p>
52
53</div>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]54
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]55
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]56<!--
57Almost dead code.
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]58 include/llvm/Analysis/LiveValues.h => Dan
59 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
60 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]61-->
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]62
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]63
64<!-- Unfinished features in 2.6:
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]65 gcc plugin.
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]66 strong phi elim
67 variable debug info for optimized code
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]68 postalloc scheduler: anti dependence breaking, hazard recognizer?
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]69 metadata
70 loop dependence analysis
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]71 ELF Writer? How stable?
72 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]73 2.7 supports the GDB 7.0 jit interfaces for debug info.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]74 -->
75
76 <!-- for announcement email:
Chris Lattnerb2d43472009-10-05 02:12:39 +0000[diff] [blame]77 Logo web page.
78 llvm devmtg
79 compiler_rt
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]80 KLEE web page at klee.llvm.org
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]81 Many new papers added to /pubs/
82 Mention gcc plugin.
83
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]84 -->
85
86<!-- *********************************************************************** -->
87<div class="doc_section">
88 <a name="subproj">Sub-project Status Update</a>
89</div>
90<!-- *********************************************************************** -->
91
92<div class="doc_text">
93<p>
94The LLVM 2.6 distribution currently consists of code from the core LLVM
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]95repository (which roughly includes the LLVM optimizers, code generators
96and supporting tools), the Clang repository and the llvm-gcc repository. In
97addition to this code, the LLVM Project includes other sub-projects that are in
98development. Here we include updates on these subprojects.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]99</p>
100
101</div>
102
103
104<!--=========================================================================-->
105<div class="doc_subsection">
106<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
107</div>
108
109<div class="doc_text">
110
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]111<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
112a set of new 'LLVM native' front-end technologies for the C family of languages.
113LLVM 2.6 is the first release to officially include Clang, and it provides a
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]114production quality C and Objective-C compiler. If you are interested in <a
115href="http://clang.llvm.org/performance.html">fast compiles</a> and
116<a href="http://clang.llvm.org/diagnostics.html">good diagnostics</a>, we
117encourage you to try it out. Clang currently compiles typical Objective-C code
1183x faster than GCC and compiles C code about 30% faster than GCC at -O0 -g
119(which is when the most pressure is on the frontend).</p>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]120
121<p>In addition to supporting these languages, C++ support is also <a
122href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
123Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
124If you are interested in Clang C++ support or any other Clang feature, we
125strongly encourage you to get involved on the <a
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]126href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
127list</a>.</p>
128
129<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
130
131<ul>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]132<li>C and Objective-C support are now considered production quality.</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]133<li>AuroraUX, FreeBSD, and OpenBSD are now supported.</li>
Chris Lattner401ec6d2009-10-09 05:01:15 +0000[diff] [blame]134<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]135<li>Many many bugs are fixed and many features have been added.</li>
136</ul>
137</div>
138
139<!--=========================================================================-->
140<div class="doc_subsection">
141<a name="clangsa">Clang Static Analyzer</a>
142</div>
143
144<div class="doc_text">
145
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]146<p><b>UPDATE!</b> Previously announced in the 2.4 and 2.5 LLVM releases, the Clang project also
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]147includes an early stage static source code analysis tool for <a
148href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
Duncan Sandsccedda42009-10-10 19:16:25 +0000[diff] [blame^]149in C and Objective-C programs. The tool performs checks to find
150bugs that occur on a specific path within a program.
151The set of checks performed by the static analyzer continues to expand, and
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]152future plans for the tool include full source-level inter-procedural analysis
153and deeper checks such as buffer overrun detection. There are many opportunities
154to extend and enhance the static analyzer, and anyone interested in working on
155this project is encouraged to get involved!</p>
156
157</div>
158
159<!--=========================================================================-->
160<div class="doc_subsection">
161<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
162</div>
163
164<div class="doc_text">
165<p>
166The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]167a JVM and a CLI Virtual Machine (Microsoft .NET is an
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]168implementation of the CLI) using LLVM for static and just-in-time
169compilation.</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]170
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]171<p>
172VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
Duncan Sands54fbb412009-06-24 08:38:48 +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>
175
176<ul>
177
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]178<li>A new llcj tool to generate shared libraries or executables of Java
179 files.</li>
Nicolas Geoffray13eff6a2009-10-09 13:17:57 +0000[diff] [blame]180<li>Cooperative garbage collection. </li>
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]181<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]182<li>Implementation of a two-word header for Java objects instead of the orginal
183 three-word header. </li>
184<li>Better Java specification-compliance: division by zero checks, stack
185 overflow checks, finalization and references support. </li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]186
187</ul>
188</div>
189
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]190
191<!--=========================================================================-->
192<div class="doc_subsection">
193<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
194</div>
195
196<div class="doc_text">
197<p>
198The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
199is a simple library that provides an implementation of the low-level
200target-specific hooks required by code generation and other runtime components.
201For example, when compiling for a 32-bit target, converting a double to a 64-bit
202unsigned integer is compiling into a runtime call to the "__fixunsdfdi"
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]203function. The compiler-rt library provides highly optimized implementations of
204this and other low-level routines (some are 3x faster than the equivalent
205libgcc routines).</p>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]206
207<p>
208All of the code in the compiler-rt project is available under the standard LLVM
209License, a "BSD-style" license.</p>
210
211</div>
212
213<!--=========================================================================-->
214<div class="doc_subsection">
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]215<a name="klee">KLEE: Symbolic Execution and Automatic Test Case Generator</a>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]216</div>
217
218<div class="doc_text">
219<p>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]220The new LLVM <a href="http://klee.llvm.org/">KLEE project</a> is a symbolic
221execution framework for programs in LLVM bitcode form. KLEE tries to
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]222symbolically evaluate "all" paths through the application and records state
223transitions that lead to fault states. This allows it to construct testcases
224that lead to faults and can even be used to verify algorithms. For more
225details, please see the <a
226href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]227KLEE.</p>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]228
229</div>
230
231<!--=========================================================================-->
232<div class="doc_subsection">
233<a name="dragonegg">Dragon Egg: An LLVM backend plugin for GCC</a>
234</div>
235
236<div class="doc_text">
237<p>
238<b>Duncan needs to write me</b>.
239</p>
240
241</div>
242
243
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]244<!--=========================================================================-->
245<div class="doc_subsection">
246<a name="mc">llvm-mc: Machine Code Toolkit</a>
247</div>
248
249<div class="doc_text">
250<p>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]251The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
252better tools for dealing with machine code, object file formats, etc. The idea
253is to be able to generate most of the target specific details of assemblers and
254disassemblers from existing LLVM target .td files (with suitable enhancements),
255and to build infrastructure for reading and writing common object file formats.
256One of the first deliverables is to build a full assembler and integrate it into
257the compiler, which is predicted to substantially reduce compile time in some
258scenarios.
259</p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]260
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]261<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
262can reliably parse and pretty print (with some encoding information) a
263darwin/x86 .s file successfully, and has the very early phases of a Mach-O
264assembler in progress. Beyond the MC framework itself, major refactoring of the
265LLVM code generator has started. The idea is to make the code generator reason
266about the code it is producing in a much more semantic way, rather than a
267textual way. For example, the code generator now uses MCSection objects to
268represent section assignments, instead of text strings that print to .section
269directives.</p>
270
271<p>MC is an early and ongoing project that will hopefully continue to lead to
272many improvements in the code generator and build infrastructure useful for many
273other situations.
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]274</p>
275
276</div>
277
278
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]279<!-- *********************************************************************** -->
280<div class="doc_section">
281 <a name="externalproj">External Projects Using LLVM 2.6</a>
282</div>
283<!-- *********************************************************************** -->
284
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]285<div class="doc_text">
286
287<p>An exciting aspect of LLVM is that it is used as an enabling technology for
288 a lot of other language and tools projects. This section lists some of the
289 projects that have already been updated to work with LLVM 2.6.</p>
290</div>
291
292
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]293<!--=========================================================================-->
294<div class="doc_subsection">
295<a name="Rubinius">Rubinius</a>
296</div>
297
298<div class="doc_text">
299<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
300for running Ruby code which strives to write as much of the core class
301implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
302uses LLVM to optimize and compile ruby code down to machine code. Techniques
303such as type feedback, method inlining, and uncommon traps are all used to
304remove dynamism from ruby execution and increase performance.</p>
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]305
306<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
307a counter based JIT, type feedback, and speculative method inlining.
308</p>
309
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]310</div>
Chris Lattner2375deb2009-09-30 06:27:22 +0000[diff] [blame]311
312<!--=========================================================================-->
313<div class="doc_subsection">
314<a name="macruby">MacRuby</a>
315</div>
316
317<div class="doc_text">
318
319<p>
320<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
321core Mac OS X technologies, such as the Objective-C common runtime and garbage
322collector, and the CoreFoundation framework. It is principally developed by
323Apple and aims at enabling the creation of full-fledged Mac OS X applications.
324</p>
325
326<p>
327MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
328expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
329handling.</p>
330
331</div>
332
333
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]334<!--=========================================================================-->
335<div class="doc_subsection">
336<a name="pure">Pure</a>
337</div>
338
339<div class="doc_text">
340<p>
341<a href="http://pure-lang.googlecode.com/">Pure</a>
342is an algebraic/functional programming language based on term rewriting.
343Programs are collections of equations which are used to evaluate expressions in
344a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
345lexical closures, a hygienic macro system (also based on term rewriting),
346built-in list and matrix support (including list and matrix comprehensions) and
347an easy-to-use C interface. The interpreter uses LLVM as a backend to
348 JIT-compile Pure programs to fast native code.</p>
349
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]350<p>Pure versions 0.31 and later have been tested and are known to work with
351LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]352</p>
353</div>
354
355
356<!--=========================================================================-->
357<div class="doc_subsection">
358<a name="ldc">LLVM D Compiler</a>
359</div>
360
361<div class="doc_text">
362<p>
363<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
364the D Programming Language using the LLVM optimizer and code generator.
365The LDC project works great with the LLVM 2.6 release. General improvements in
366this
367cycle have included new inline asm constraint handling, better debug info
368support, general bugfixes, and better x86-64 support. This has allowed
369some major improvements in LDC, getting us much closer to being as
370fully featured as the original DMD compiler from DigitalMars.
371</p>
372</div>
373
374<!--=========================================================================-->
375<div class="doc_subsection">
376<a name="RoadsendPHP">Roadsend PHP</a>
377</div>
378
379<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]380<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]381<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]382source implementation of the PHP programming
383language that uses LLVM for its optimizer, JIT, and static compiler. This is a
384reimplementation of an earlier project that is now based on LLVM.</p>
385</div>
386
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]387<!--=========================================================================-->
388<div class="doc_subsection">
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]389<a name="UnladenSwallow">Unladen Swallow</a>
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]390</div>
391
392<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]393<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]394<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]395branch of <a href="http://python.org/">Python</a> intended to be fully
396compatible and significantly faster. It uses LLVM's optimization passes and JIT
397compiler.</p>
398</div>
399
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]400<!--=========================================================================-->
401<div class="doc_subsection">
402<a name="llvm-lua">llvm-lua</a>
403</div>
404
405<div class="doc_text">
406<p>
407<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
408&amp; static compiling support to the Lua VM. Lua bytecode is analyzed to
409remove type checks, then LLVM is used to compile those bytecodes down to machine
410code.</p>
411</div>
412
Jeffrey Yasskin123b3922009-06-24 21:26:42 +0000[diff] [blame]413
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]414
415<!-- *********************************************************************** -->
416<div class="doc_section">
417 <a name="whatsnew">What's New in LLVM 2.6?</a>
418</div>
419<!-- *********************************************************************** -->
420
421<div class="doc_text">
422
423<p>This release includes a huge number of bug fixes, performance tweaks, and
424minor improvements. Some of the major improvements and new features are listed
425in this section.
426</p>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]427
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]428</div>
429
430<!--=========================================================================-->
431<div class="doc_subsection">
432<a name="majorfeatures">Major New Features</a>
433</div>
434
435<div class="doc_text">
436
437<p>LLVM 2.6 includes several major new capabilities:</p>
438
439<ul>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]440<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">KLEE</a>,
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]441 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
442<li>Debug information now includes line numbers when optimizations are enabled.
443 This allows statistical sampling tools like oprofile and Shark to map
444 samples back to source lines.</li>
445<li>LLVM now includes new experimental backends to support the MSP430, SystemZ,
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]446 and BlackFin architectures.</li>
447<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
448 enables support for <a href="LinkTimeOptimization.html">transparent
449 link-time optimization</a> on ELF targets when used with the Gold binutils
450 linker.</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]451<li>LLVM now supports doing optimization and code generation on multiple
452 threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
453 Programmer's Manual</a> for more information.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]454<li>LLVM now has experimental support for <a
455 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
456 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
457 final and the .bc file format may change in future releases. Debug info
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]458 does not yet use this format in LLVM 2.6.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]459</ul>
460
461</div>
462
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]463<!--=========================================================================-->
464<div class="doc_subsection">
465<a name="coreimprovements">LLVM IR and Core Improvements</a>
466</div>
467
468<div class="doc_text">
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]469<p>LLVM IR has several new features for better support of new targets and that
470expose new optimization opportunities:</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]471
472<ul>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]473<li>The <a href="LangRef.html#i_add">add</a>, <a
474 href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
475 instructions have been split into integer and floating point version (like
476 divide and remainder), introducing new <a
477 href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
478 and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
479<li>The <a href="LangRef.html#i_add">add</a>, <a
480 href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
481 instructions now support optional "nsw" and "nuw" bits which indicate that
482 the operation is guaranteed to not overflow (in the signed or
483 unsigned case, respectively). This gives the optimizer more information and
484 can be used for things C signed integer values, which are undefined on
485 overflow.</li>
486<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
487 optional "exact" flag which indicates that the result of the division is
488 guaranteed to have a remainder of zero. This is useful to optimize pointer
489 subtraction in C.</li>
490<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
491 supports arbitrary integer index values for array/pointer indices. This
492 allows for better better code generation on 16-bit targets like PIC16.</li>
493<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
494 supports an "inbounds" optimization hint that tells the optimizer that the
495 pointer is guaranteed to be within its allocated object.</li>
496<li>LLVM now support a series of new linkage types for global values which allow
497 for better optimization and new capabilities:
498 <ul>
499 <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
500 <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
501 semantics as the non-"odr" linkage types. The difference is that these
502 linkage types indicate that all definitions of the specified function
503 are guaranteed to have the same semantics. This allows inlining
504 templates functions in C++ but not inlining weak functions in C,
505 which previously both got the same linkage type.</li>
506 <li><a href="LangRef.html#linkage_available_externally">available_externally
507 </a> is a new linkage type that gives the optimizer visibility into the
508 definition of a function (allowing inlining and side effect analysis)
509 but that does not cause code to be generated. This allows better
510 optimization of "GNU inline" functions, extern templates, etc.</li>
511 <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
512 new linkage type (which is only useful on Mac OS X) that is used for
513 some metadata generation and other obscure things.</li>
514 </ul></li>
515<li>Finally, target-specific intrinsics can now return multiple values, which
516 is useful for modeling target operations with multiple results.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]517</ul>
518
519</div>
520
521<!--=========================================================================-->
522<div class="doc_subsection">
523<a name="optimizer">Optimizer Improvements</a>
524</div>
525
526<div class="doc_text">
527
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]528<p>In addition to a large array of minor performance tweaks and bug fixes, this
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]529release includes a few major enhancements and additions to the optimizers:</p>
530
531<ul>
532
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]533<li>The <a href="Passes.html#scalarrepl">Scalar Replacement of Aggregates</a>
534 pass has many improvements that allow it to better promote vector unions,
535 variables which are memset, and much more strange code that can happen do
536 to bitfield accesses to register operations. An interesting change is that
537 it now produces "unusual" integer sizes (like i1704) in some cases and lets
538 other optimizers clean things up.</li>
539<li>The <a href="Passes.html#loop-reduce">Loop Strength Reduction</a> pass now
540 promotes small integer induction variables to 64-bit on 64-bit targets,
541 which provides a major performance boost many for numerical code. It also
542 promotes shorts to int on 32-bit hosts, etc. LSR now also analyzes pointer
543 expressions (e.g. getelementptrs), as well as integers.</li>
544<li>The <a href="Passes.html#gvn">GVN</a> pass now eliminates partial
545 redundancies of loads in simple cases.</li>
546<li>The <a href="Passes.html#inline">Inliner</a> now reuses stack space when
547 inlining similiar arrays from multiple callees into one caller.</li>
548<li>LLVM includes a new experimental Static Single Information (SSI)
549 construction pass.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]550</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]551
552</ul>
553
554</div>
555
556<!--=========================================================================-->
557<div class="doc_subsection">
558<a name="codegen">Target Independent Code Generator Improvements</a>
559</div>
560
561<div class="doc_text">
562
563<p>We have put a significant amount of work into the code generator
564infrastructure, which allows us to implement more aggressive algorithms and make
565it run faster:</p>
566
567<ul>
568
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]569<li>The <tt>llc -asm-verbose</tt> option (exposed from llvm-gcc and clang as
570 <tt>-fverbose-asm</tt>) now adds a lot of useful information in comments to
571 the generated .s file. This information includes location information (if
572 built with <tt>-g</tt>) and loop nest information.</li>
573<li>The code generator now supports a new MachineVerifier pass which is useful
574 for finding bugs in targets and ccodegen passes.</li>
575<li>The Machine LICM is now enabled by default. It hoists instructions out of
576 loops (such as constant pool loads, loads from readonly stubs, vector
577 constant synthesization code, etc) and is currently configured to only do so
578 when the hoisted operation can be rematerialized.</li>
579<li>The Machine Sinking pass is now enabled by default. This pass moves
580 side-effect free operations down the CFG so that they are executed on fewer
581 paths through a function.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]582<li>Tblgen now supports multiclass inheritance and a number of new string and
583 list operations like !(subst), !(foreach), !car, !cdr, !null, !if, !cast.
584 These make the .td files more expressive and allow more aggressive factoring
585 of duplication across instruction patterns.</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]586<li>Target-specific intrinsics can now be added without having to hack VMCore to
587 add them. This makes it easier to maintain out-of-tree targets.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]588<li>Regalloc improvements for commuting, various spiller peephole optimizations, cross-class coalescing.</li>
589<li><tt>llc -enable-value-prop</tt>, propagation of value info (sign/zero ext info) from one MBB to another</li>
590<li>Regalloc hints for allocation stuff: Evan r73381/r73671. Finished/enabled?</li>
591<li>Stack slot coloring for register spills (denser stack frames)</li>
592<li>SelectionDAGS: New BuildVectorSDNode (r65296), and ISD::VECTOR_SHUFFLE (r69952 / PR2957)</li>
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]593<li>The Prolog/Epilog Insertion Pass now has experimental support for performing
594 the "shrink wrapping" optimization, which moves spills and reloads around in
595 the CFG to avoid doing saves on paths that don't need them.</li>
596<li>LLVM includes new experimental support for writing ELF .o files directly
597 from the compiler. It works well for many simple C testcases, but doesn't
598 support exception handling, debug info, inline assembly, etc.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]599<li>Targets can now specify register allocation hints through
Chris Lattner51ead6d2009-10-10 19:00:55 +0000[diff] [blame]600 MachineRegisterInfo:: setRegAllocationHint. A regalloc hint consists of hint
601 type and physical register number. A hint type of zero specifies a register
602 allocation preference. Other hint type values are target specific which are
603 resolved by TargetRegisterInfo::ResolveRegAllocHint. An example of which is
604 the ARM target can uses register hint to request that the register allocator
605 provide an even / odd register pair to two virtual registers.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]606</ul>
607</div>
608
609<!--=========================================================================-->
610<div class="doc_subsection">
611<a name="x86">X86-32 and X86-64 Target Improvements</a>
612</div>
613
614<div class="doc_text">
615<p>New features of the X86 target include:
616</p>
617
618<ul>
619
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]620<li>Preliminary support for addrspace 256 -> GS, 257 -> FS, known problems: CodeGenerator.html#x86_memory</li>
621<li>Support for softfloat modes, typically used by OS kernels.</li>
622
623<li>X86-64: better modeling of implicit zero extensions, eliminates a lot of redundant zexts</li>
624<li>X86-64 TLS support for local exec and initial exec.</li>
625<li>Better modeling of H registerts as subregs.</li>
626<li>Vector icmp/fcmp now work with SSE codegen.</li>
627<li>SSE 4.2 support.</li>
628<li>all global variable reference logic is now in ClassifyGlobalReference.</li>
629</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]630</ul>
631
632</div>
633
634<!--=========================================================================-->
635<div class="doc_subsection">
636<a name="pic16">PIC16 Target Improvements</a>
637</div>
638
639<div class="doc_text">
640<p>New features of the PIC16 target include:
641</p>
642
643<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]644<li>Support for floating-point, indirect function calls, and
645 passing/returning aggregate types to functions.
646<li>The code generator is able to generate debug info into output COFF files.
647<li>Support for placing an object into a specific section or at a specific
648 address in memory.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]649</ul>
650
651<p>Things not yet supported:</p>
652
653<ul>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]654<li>Variable arguments.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]655<li>Interrupts/programs.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]656</ul>
657
658</div>
659
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]660<!--=========================================================================-->
661<div class="doc_subsection">
662<a name="ARM">ARM Target Improvements</a>
663</div>
664
665<div class="doc_text">
666<p>New features of the ARM target include:
667</p>
668
669<ul>
670
671<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel16eac042009-08-20 15:01:16 +0000[diff] [blame]672that implement version v7-A of the ARM architecture. The ARM backend now
673supports both the Thumb2 and Advanced SIMD (Neon) instruction sets. The
674AAPCS-VFP "hard float" calling conventions are also supported with the
675<tt>-float-abi=hard</tt> flag. These features are still somewhat experimental
676and subject to change. The Neon intrinsics, in particular, may change in future
677releases of LLVM.
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]678</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]679
680 ARM AAPCS-VFP hard float ABI is supported.
681 ARM calling convention code is now tblgen generated instead of manual.
682 ARM: NEON support. neonfp for doing single precision fp with neon instead of VFP.
683
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]684</ul>
685
686</div>
687
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]688<!--=========================================================================-->
689<div class="doc_subsection">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]690<a name="OtherTarget">Other Target Specific Improvements</a>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]691</div>
692
693<div class="doc_text">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]694<p>New features of other targets include:
695</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]696
697<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]698<li>Mips now supports O32 Calling Convention.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]699<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
700 support, lots of bugs fixed.</li>
701<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
702 Needs more testing.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]703</ul>
704
705</div>
706
707<!--=========================================================================-->
708<div class="doc_subsection">
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]709<a name="executionengine">Interpreter and JIT Improvements</a>
710</div>
711
712<div class="doc_text">
713
714<ul>
715<li>The JIT now supports generating more than 16M of code.</li>
716<li>When configured with --with-oprofile, the JIT can now inform oprofile about
717 JIT'd code, allowing oprofile to get line number and function name
718 information for JIT'd functions.</li>
719<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
720 calling almost arbitrary external (natively compiled) functions.</li>
721<li>Clients of the JIT can now register a 'JITEventListener' object to receive
722 callbacks when the JIT emits or frees machine code. The OProfile support
723 uses this mechanism.</li>
724</ul>
725
726</div>
727
728
729<!--=========================================================================-->
730<div class="doc_subsection">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]731<a name="newapis">New Useful APIs</a>
732</div>
733
734<div class="doc_text">
735
736<ul>
737<li>New EngineBuilder class for creating JITs: r76276</li>
738 New PrettyStackTrace, crashes of llvm tools should give some indication of what the compiler was doing at the time of the crash (e.g. running a pass), and print out command line arguments.
739 StringRef class, Twine class.
740 New WeakVH and AssertingVH and CallbackVH classes.
741 New llvm/ADT/Triple class.
742 llvm_report_error() error handling API (llvm/Support/ErrorHandling.h)
743 New llvm/System/Atomic.h, llvm/System/RWMutex.h for portable atomic ops, rw locks.
744 New SourceMgr, SMLoc classes for simple parsers with caret diagnostics and #include support, (used by
745 tablegen, llvm-mc, the .ll parser, FileCheck, etc)
746
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]747</ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]748
749
750</div>
751
752<!--=========================================================================-->
753<div class="doc_subsection">
754<a name="otherimprovements">Other Improvements and New Features</a>
755</div>
756
757<div class="doc_text">
758<p>Other miscellaneous features include:</p>
759
760<ul>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]761<li>LLVM now includes a new internal '<a
762 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
763 writing much more accurate regression tests that run faster. Please see the
764 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
765 Guide</a> for more information.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]766<li>LLVM profile information support has been significantly improved to produce
767correct use counts, and has support for edge profiling with reduced runtime
768overhead. Combined, the generated profile information is both more correct and
769imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
770CPU2000).</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]771<li>Many extensions to the C APIs.</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]772<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
773programming language.</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]774
775<li>LLVMC:
776
777* Dynamic plugins now work on Windows.
778* New option property: init. Makes possible to provide default values for
779 options defined in plugins (interface to cl::init).
780* New example: Skeleton, shows how to create a standalone LLVMC-based driver.
781* New example: mcc16, a driver for the PIC16 toolchain.</li>
782
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]783</ul>
784
785</div>
786
787
788<!--=========================================================================-->
789<div class="doc_subsection">
790<a name="changes">Major Changes and Removed Features</a>
791</div>
792
793<div class="doc_text">
794
795<p>If you're already an LLVM user or developer with out-of-tree changes based
Owen Andersonbe3fe4e2009-07-02 16:48:38 +0000[diff] [blame]796on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]797from the previous release.</p>
798
799<ul>
800
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]801<li>The Itanium (IA64) backend has been removed. It was not supported and
802 bitrotted.</li>
803<li>The BigBlock register allocator has been removed, it also bitrotted.</li>
804<li>The C Backend (-march=c) is no longer considered part of the LLVM release
805criteria. We still want it to work, but no one is maintaining it and it lacks
806support for arbitrary precision integers and other important IR features.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]807</ul>
808
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]809 LLVM build now builds all libraries as .a files instead of some
810 libraries as relinked .o files. This requires some APIs like
811 InitializeAllTargets.h. TargetRegistry!
812
813
814
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]815
816<p>In addition, many APIs have changed in this release. Some of the major LLVM
817API changes are:</p>
818
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]819
820 API Cleanup:
821 no use of hash_set/hash_map, no more llvm::OStream
822 Use raw_ostream for everything, killed off llvm/Streams.h and DOUT
823
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]824<ul>
Owen Andersonbe3fe4e2009-07-02 16:48:38 +0000[diff] [blame]825<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
826 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
827 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
828 for clients that will only ever use a single context, the new
829 <tt>getGlobalContext()</tt> API can be used to access a default global
830 context which can be passed in any and all cases where a context is
831 required.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]832<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohman79537c92009-07-07 20:05:15 +0000[diff] [blame]833<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
834 overloaded for floating-point types. Floating-point addition, subtraction,
835 and multiplication are now represented with new operators <tt>FAdd</tt>,
836 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
837 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
838 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
839 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
840 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbara7d9e052009-07-12 20:41:27 +0000[diff] [blame]841<li>The DynamicLibrary class can no longer be constructed, its functionality has
842 moved to static member functions.</li>
Dan Gohmanb6b11702009-07-15 19:59:19 +0000[diff] [blame]843<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
844 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
845 <tt>false</tt>, an error will be reported if a file with the given name
846 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
847 be silently truncated (which is the behavior before this flag was
848 added).</li>
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]849<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
850longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
851used.</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]852
Daniel Dunbare3572ba2009-07-25 04:41:11 +0000[diff] [blame]853<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
854and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
855or <tt>std::string</tt>, as described in
856the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]857clients should be unaffected by this transition, unless they are used to <tt>Value::getName()</tt> returning a string. Here are some tips on updating to 2.6:
858 <ul>
859 <li><tt>getNameStr()</tt> is still available, and matches the old
860 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
861 although more efficient alternatives are now possible.</li>
862
863 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
864 a <tt>std::ostream</tt>, consider migrating
865 to <tt>llvm::raw_ostream</tt>.</li>
866
867 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
868 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
869 Note that this string (as before), may not be the entire name if the
870 name containts embedded null characters.</li>
871
872 <li>If you were using operator plus on the result of <tt>getName()</tt> and
873 treating the result as an <tt>std::string</tt>, you can either
874 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
875 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbare03513b2009-07-25 23:55:21 +0000[diff] [blame]876
877 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramer7b2136d2009-08-05 15:42:44 +0000[diff] [blame]878 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]879 </ul>
880</li>
881
Daniel Dunbar48224ee2009-07-26 02:12:58 +0000[diff] [blame]882<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbarc9a70092009-07-26 05:41:39 +0000[diff] [blame]883previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
884 <ul>
885 <li><tt>TargetMachineRegistry</tt> has been renamed
886 to <tt>TargetRegistry</tt>.</li>
887
888 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
889 function to find targets.</li>
890 </ul>
891</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]892
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]893<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbare3572ba2009-07-25 04:41:11 +0000[diff] [blame]894FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
895This is not an API change, maybe there should be a tool changes section?</li>
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]896<li>temporarely due to Context API change passes should call doInitialization()
897method of the pass they inherit from, otherwise Context is NULL.
898FIXME: remove this entry when this is no longer needed.<li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]899</ul>
900
901</div>
902
903
904
905<!-- *********************************************************************** -->
906<div class="doc_section">
907 <a name="portability">Portability and Supported Platforms</a>
908</div>
909<!-- *********************************************************************** -->
910
911<div class="doc_text">
912
913<p>LLVM is known to work on the following platforms:</p>
914
915<ul>
916<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]917Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]918<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
919and 64-bit modes.</li>
920<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
921<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
922 support is available for native builds with Visual C++).</li>
923<li>Sun UltraSPARC workstations running Solaris 10.</li>
924<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]925</ul>
926
927<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
928to the machine and operating system on which it is built. However, minor
929porting may be required to get LLVM to work on new platforms. We welcome your
930portability patches and reports of successful builds or error messages.</p>
931
932</div>
933
934<!-- *********************************************************************** -->
935<div class="doc_section">
936 <a name="knownproblems">Known Problems</a>
937</div>
938<!-- *********************************************************************** -->
939
940<div class="doc_text">
941
942<p>This section contains significant known problems with the LLVM system,
943listed by component. If you run into a problem, please check the <a
944href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
945there isn't already one.</p>
946
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]947<ul>
Chris Lattner4050d252009-07-21 23:17:26 +0000[diff] [blame]948<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]949using the stock GCC 3.x.x series 'out the box',
950See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
951However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
952for x86/x64 has been made available from the third party AuroraUX Project
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]953that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]954</ul>
955
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]956</div>
957
958<!-- ======================================================================= -->
959<div class="doc_subsection">
960 <a name="experimental">Experimental features included with this release</a>
961</div>
962
963<div class="doc_text">
964
965<p>The following components of this LLVM release are either untested, known to
966be broken or unreliable, or are in early development. These components should
967not be relied on, and bugs should not be filed against them, but they may be
968useful to some people. In particular, if you would like to work on one of these
969components, please contact us on the <a
970href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
971
972<ul>
Dan Gohman2a5ddf32009-07-24 00:30:09 +0000[diff] [blame]973<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]974<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
975 supported value for this option.</li>
976</ul>
977
978</div>
979
980<!-- ======================================================================= -->
981<div class="doc_subsection">
982 <a name="x86-be">Known problems with the X86 back-end</a>
983</div>
984
985<div class="doc_text">
986
987<ul>
988 <li>The X86 backend does not yet support
989 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
990 floating point stack</a>. It supports the 'f' and 't' constraints, but not
991 'u'.</li>
992 <li>The X86 backend generates inefficient floating point code when configured
993 to generate code for systems that don't have SSE2.</li>
994 <li>Win64 code generation wasn't widely tested. Everything should work, but we
995 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
996 runtime currently due
997 to <a href="http://llvm.org/PR2255">several</a>
998 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
999 the
1000 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
1001 <li>The X86-64 backend does not yet support the LLVM IR instruction
1002 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
1003 argument constructs on X86-64 by lowering them manually.</li>
1004</ul>
1005
1006</div>
1007
1008<!-- ======================================================================= -->
1009<div class="doc_subsection">
1010 <a name="ppc-be">Known problems with the PowerPC back-end</a>
1011</div>
1012
1013<div class="doc_text">
1014
1015<ul>
1016<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1017compilation, and lacks support for debug information.</li>
1018</ul>
1019
1020</div>
1021
1022<!-- ======================================================================= -->
1023<div class="doc_subsection">
1024 <a name="arm-be">Known problems with the ARM back-end</a>
1025</div>
1026
1027<div class="doc_text">
1028
1029<ul>
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]1030<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
1031and not well tested. Some features may not work at all, and the code quality
1032may be poor in some cases.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1033<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
1034processors, thumb programs can crash or produce wrong
1035results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
1036<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
1037</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1038</ul>
1039
1040</div>
1041
1042<!-- ======================================================================= -->
1043<div class="doc_subsection">
1044 <a name="sparc-be">Known problems with the SPARC back-end</a>
1045</div>
1046
1047<div class="doc_text">
1048
1049<ul>
1050<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
1051 support the 64-bit SPARC ABI (-m64).</li>
1052</ul>
1053
1054</div>
1055
1056<!-- ======================================================================= -->
1057<div class="doc_subsection">
1058 <a name="mips-be">Known problems with the MIPS back-end</a>
1059</div>
1060
1061<div class="doc_text">
1062
1063<ul>
1064<li>The O32 ABI is not fully supported.</li>
1065<li>64-bit MIPS targets are not supported yet.</li>
1066</ul>
1067
1068</div>
1069
1070<!-- ======================================================================= -->
1071<div class="doc_subsection">
1072 <a name="alpha-be">Known problems with the Alpha back-end</a>
1073</div>
1074
1075<div class="doc_text">
1076
1077<ul>
1078
1079<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1080appropriate nops inserted to ensure restartability.</li>
1081
1082</ul>
1083</div>
1084
1085<!-- ======================================================================= -->
1086<div class="doc_subsection">
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1087 <a name="c-be">Known problems with the C back-end</a>
1088</div>
1089
1090<div class="doc_text">
1091
1092<ul>
1093<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1094 inline assembly code</a>.</li>
1095<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1096 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1097 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1098<li>The C backend does not support all exception handling constructs.</li>
1099<li>The C backend does not support arbitrary precision integers.</li>
1100</ul>
1101
1102</div>
1103
1104
1105<!-- ======================================================================= -->
1106<div class="doc_subsection">
1107 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
1108</div>
1109
1110<div class="doc_text">
1111
1112<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
1113Optimization</a> on most platforms "out-of-the-box". Please inquire on the
1114LLVMdev mailing list if you are interested.</p>
1115
1116<p>The only major language feature of GCC not supported by llvm-gcc is
1117 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1118 are only supported on some targets. For example, trampolines are only
1119 supported on some targets (these are used when you take the address of a
1120 nested function).</p>
1121
1122<p>If you run into GCC extensions which are not supported, please let us know.
1123</p>
1124
1125</div>
1126
1127<!-- ======================================================================= -->
1128<div class="doc_subsection">
1129 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
1130</div>
1131
1132<div class="doc_text">
1133
1134<p>The C++ front-end is considered to be fully
1135tested and works for a number of non-trivial programs, including LLVM
1136itself, Qt, Mozilla, etc.</p>
1137
1138<ul>
1139<li>Exception handling works well on the X86 and PowerPC targets. Currently
1140 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
1141</ul>
1142
1143</div>
1144
1145<!-- ======================================================================= -->
1146<div class="doc_subsection">
1147 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1148</div>
1149
1150<div class="doc_text">
1151<ul>
1152<li>Fortran support generally works, but there are still several unresolved bugs
1153 in Bugzilla. Please see the tools/gfortran component for details.</li>
1154</ul>
1155</div>
1156
1157<!-- ======================================================================= -->
1158<div class="doc_subsection">
1159 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1160</div>
1161
1162<div class="doc_text">
1163The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1164technology, and problems should be expected.
1165<ul>
1166<li>The Ada front-end currently only builds on X86-32. This is mainly due
1167to lack of trampoline support (pointers to nested functions) on other platforms.
1168However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1169which does support trampolines.</li>
1170<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1171This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1172exception handling, which is used internally by the compiler.
1173Workaround: configure with --disable-bootstrap.</li>
1174<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1175and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1176(c380004 also fails with gcc-4.2 mainline).
1177If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1178causes the compiler to go into an infinite loop, using up all system memory.</li>
1179<li>Some GCC specific Ada tests continue to crash the compiler.</li>
1180<li>The -E binder option (exception backtraces)
1181<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1182crashing if an exception is raised. Workaround: do not use -E.</li>
1183<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1184or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1185or use representation clauses that result in a field of a non-discrete type
1186starting or finishing in the middle of a byte.</li>
1187<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1188'main' as generated by the Ada binder to be invalid</a>.
1189Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1190<tt>envp</tt> rather than integers.</li>
1191<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1192ignored</a>.</li>
1193</ul>
1194</div>
1195
Erick Tryzelaarb4cf9752009-09-28 04:42:55 +0000[diff] [blame]1196<!-- ======================================================================= -->
1197<div class="doc_subsection">
1198 <a name="ocaml-bindingse">Known problems with the O'Caml bindings</a>
1199</div>
1200
1201<div class="doc_text">
1202
1203<p>The Llvm.Linkage module is broken, and has incorrect values. Only
1204Llvm.Linkage.External, Llvm.Linkage.Available_externally, and
1205Llvm.Linkage.Link_once will be correct. If you need any of the other linkage
1206modes, you'll have to write an external C library in order to expose the
1207functionality. This has been fixed in the trunk.</p>
1208</div>
1209
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1210<!-- *********************************************************************** -->
1211<div class="doc_section">
1212 <a name="additionalinfo">Additional Information</a>
1213</div>
1214<!-- *********************************************************************** -->
1215
1216<div class="doc_text">
1217
1218<p>A wide variety of additional information is available on the <a
1219href="http://llvm.org">LLVM web page</a>, in particular in the <a
1220href="http://llvm.org/docs/">documentation</a> section. The web page also
1221contains versions of the API documentation which is up-to-date with the
1222Subversion version of the source code.
1223You can access versions of these documents specific to this release by going
1224into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1225
1226<p>If you have any questions or comments about LLVM, please feel free to contact
1227us via the <a href="http://llvm.org/docs/#maillist"> mailing
1228lists</a>.</p>
1229
1230</div>
1231
1232<!-- *********************************************************************** -->
1233
1234<hr>
1235<address>
1236 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1237 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
1238 <a href="http://validator.w3.org/check/referer"><img
1239 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
1240
1241 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
1242 Last modified: $Date$
1243</address>
1244
1245</body>
1246</html>