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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 Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]80 klee web page at klee.llvm.org
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>
149in C and Objective-C programs. The tool performs a growing set of checks to find
150bugs that occur on a specific path within a program.</p>
151
152<p>In the LLVM 2.6 time-frame there have been many significant improvements to
153XYZ.</p>
154
155<p>The set of checks performed by the static analyzer continues to expand, and
156future plans for the tool include full source-level inter-procedural analysis
157and deeper checks such as buffer overrun detection. There are many opportunities
158to extend and enhance the static analyzer, and anyone interested in working on
159this project is encouraged to get involved!</p>
160
161</div>
162
163<!--=========================================================================-->
164<div class="doc_subsection">
165<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
166</div>
167
168<div class="doc_text">
169<p>
170The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]171a JVM and a CLI Virtual Machine (Microsoft .NET is an
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]172implementation of the CLI) using LLVM for static and just-in-time
173compilation.</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]174
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]175<p>
176VMKit 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]177<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
178bug fixes, cleanup and new features. The major changes are:</p>
179
180<ul>
181
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]182<li>A new llcj tool to generate shared libraries or executables of Java
183 files.</li>
Nicolas Geoffray13eff6a2009-10-09 13:17:57 +0000[diff] [blame]184<li>Cooperative garbage collection. </li>
Nicolas Geoffray12c0e562009-10-09 10:13:08 +0000[diff] [blame]185<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
Nicolas Geoffray0dcee362009-10-09 10:17:14 +0000[diff] [blame]186<li>Implementation of a two-word header for Java objects instead of the orginal
187 three-word header. </li>
188<li>Better Java specification-compliance: division by zero checks, stack
189 overflow checks, finalization and references support. </li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]190
191</ul>
192</div>
193
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]194
195<!--=========================================================================-->
196<div class="doc_subsection">
197<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
198</div>
199
200<div class="doc_text">
201<p>
202The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
203is a simple library that provides an implementation of the low-level
204target-specific hooks required by code generation and other runtime components.
205For example, when compiling for a 32-bit target, converting a double to a 64-bit
206unsigned integer is compiling into a runtime call to the "__fixunsdfdi"
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]207function. The compiler-rt library provides highly optimized implementations of
208this and other low-level routines (some are 3x faster than the equivalent
209libgcc routines).</p>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]210
211<p>
212All of the code in the compiler-rt project is available under the standard LLVM
213License, a "BSD-style" license.</p>
214
215</div>
216
217<!--=========================================================================-->
218<div class="doc_subsection">
219<a name="klee">klee: Symbolic Execution and Automatic Test Case Generator</a>
220</div>
221
222<div class="doc_text">
223<p>
224The new LLVM <a href="http://klee.llvm.org/">klee project</a> is a symbolic
225execution framework for programs in LLVM bitcode form. Klee tries to
226symbolically evaluate "all" paths through the application and records state
227transitions that lead to fault states. This allows it to construct testcases
228that lead to faults and can even be used to verify algorithms. For more
229details, please see the <a
230href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
231Klee.</p>
232
233</div>
234
235<!--=========================================================================-->
236<div class="doc_subsection">
237<a name="dragonegg">Dragon Egg: An LLVM backend plugin for GCC</a>
238</div>
239
240<div class="doc_text">
241<p>
242<b>Duncan needs to write me</b>.
243</p>
244
245</div>
246
247
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]248<!--=========================================================================-->
249<div class="doc_subsection">
250<a name="mc">llvm-mc: Machine Code Toolkit</a>
251</div>
252
253<div class="doc_text">
254<p>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]255The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
256better tools for dealing with machine code, object file formats, etc. The idea
257is to be able to generate most of the target specific details of assemblers and
258disassemblers from existing LLVM target .td files (with suitable enhancements),
259and to build infrastructure for reading and writing common object file formats.
260One of the first deliverables is to build a full assembler and integrate it into
261the compiler, which is predicted to substantially reduce compile time in some
262scenarios.
263</p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]264
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]265<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
266can reliably parse and pretty print (with some encoding information) a
267darwin/x86 .s file successfully, and has the very early phases of a Mach-O
268assembler in progress. Beyond the MC framework itself, major refactoring of the
269LLVM code generator has started. The idea is to make the code generator reason
270about the code it is producing in a much more semantic way, rather than a
271textual way. For example, the code generator now uses MCSection objects to
272represent section assignments, instead of text strings that print to .section
273directives.</p>
274
275<p>MC is an early and ongoing project that will hopefully continue to lead to
276many improvements in the code generator and build infrastructure useful for many
277other situations.
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]278</p>
279
280</div>
281
282
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]283<!-- *********************************************************************** -->
284<div class="doc_section">
285 <a name="externalproj">External Projects Using LLVM 2.6</a>
286</div>
287<!-- *********************************************************************** -->
288
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]289<div class="doc_text">
290
291<p>An exciting aspect of LLVM is that it is used as an enabling technology for
292 a lot of other language and tools projects. This section lists some of the
293 projects that have already been updated to work with LLVM 2.6.</p>
294</div>
295
296
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]297<!--=========================================================================-->
298<div class="doc_subsection">
299<a name="Rubinius">Rubinius</a>
300</div>
301
302<div class="doc_text">
303<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
304for running Ruby code which strives to write as much of the core class
305implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
306uses LLVM to optimize and compile ruby code down to machine code. Techniques
307such as type feedback, method inlining, and uncommon traps are all used to
308remove dynamism from ruby execution and increase performance.</p>
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]309
310<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
311a counter based JIT, type feedback, and speculative method inlining.
312</p>
313
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]314</div>
Chris Lattner2375deb2009-09-30 06:27:22 +0000[diff] [blame]315
316<!--=========================================================================-->
317<div class="doc_subsection">
318<a name="macruby">MacRuby</a>
319</div>
320
321<div class="doc_text">
322
323<p>
324<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
325core Mac OS X technologies, such as the Objective-C common runtime and garbage
326collector, and the CoreFoundation framework. It is principally developed by
327Apple and aims at enabling the creation of full-fledged Mac OS X applications.
328</p>
329
330<p>
331MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
332expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
333handling.</p>
334
335</div>
336
337
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]338<!--=========================================================================-->
339<div class="doc_subsection">
340<a name="pure">Pure</a>
341</div>
342
343<div class="doc_text">
344<p>
345<a href="http://pure-lang.googlecode.com/">Pure</a>
346is an algebraic/functional programming language based on term rewriting.
347Programs are collections of equations which are used to evaluate expressions in
348a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
349lexical closures, a hygienic macro system (also based on term rewriting),
350built-in list and matrix support (including list and matrix comprehensions) and
351an easy-to-use C interface. The interpreter uses LLVM as a backend to
352 JIT-compile Pure programs to fast native code.</p>
353
Chris Lattner59a30272009-10-08 16:01:33 +0000[diff] [blame]354<p>Pure versions 0.31 and later have been tested and are known to work with
355LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]356</p>
357</div>
358
359
360<!--=========================================================================-->
361<div class="doc_subsection">
362<a name="ldc">LLVM D Compiler</a>
363</div>
364
365<div class="doc_text">
366<p>
367<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
368the D Programming Language using the LLVM optimizer and code generator.
369The LDC project works great with the LLVM 2.6 release. General improvements in
370this
371cycle have included new inline asm constraint handling, better debug info
372support, general bugfixes, and better x86-64 support. This has allowed
373some major improvements in LDC, getting us much closer to being as
374fully featured as the original DMD compiler from DigitalMars.
375</p>
376</div>
377
378<!--=========================================================================-->
379<div class="doc_subsection">
380<a name="RoadsendPHP">Roadsend PHP</a>
381</div>
382
383<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]384<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]385<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]386source implementation of the PHP programming
387language that uses LLVM for its optimizer, JIT, and static compiler. This is a
388reimplementation of an earlier project that is now based on LLVM.</p>
389</div>
390
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]391<!--=========================================================================-->
392<div class="doc_subsection">
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]393<a name="UnladenSwallow">Unladen Swallow</a>
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]394</div>
395
396<div class="doc_text">
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]397<p>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]398<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
Jeffrey Yasskin3a07d2f2009-06-24 21:09:13 +0000[diff] [blame]399branch of <a href="http://python.org/">Python</a> intended to be fully
400compatible and significantly faster. It uses LLVM's optimization passes and JIT
401compiler.</p>
402</div>
403
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]404<!--=========================================================================-->
405<div class="doc_subsection">
406<a name="llvm-lua">llvm-lua</a>
407</div>
408
409<div class="doc_text">
410<p>
411<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
412&amp; static compiling support to the Lua VM. Lua bytecode is analyzed to
413remove type checks, then LLVM is used to compile those bytecodes down to machine
414code.</p>
415</div>
416
Jeffrey Yasskin123b3922009-06-24 21:26:42 +0000[diff] [blame]417
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]418
419<!-- *********************************************************************** -->
420<div class="doc_section">
421 <a name="whatsnew">What's New in LLVM 2.6?</a>
422</div>
423<!-- *********************************************************************** -->
424
425<div class="doc_text">
426
427<p>This release includes a huge number of bug fixes, performance tweaks, and
428minor improvements. Some of the major improvements and new features are listed
429in this section.
430</p>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]431
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]432</div>
433
434<!--=========================================================================-->
435<div class="doc_subsection">
436<a name="majorfeatures">Major New Features</a>
437</div>
438
439<div class="doc_text">
440
441<p>LLVM 2.6 includes several major new capabilities:</p>
442
443<ul>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]444<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">klee</a>,
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]445 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
446<li>Debug information now includes line numbers when optimizations are enabled.
447 This allows statistical sampling tools like oprofile and Shark to map
448 samples back to source lines.</li>
449<li>LLVM now includes new experimental backends to support the MSP430, SystemZ,
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]450 and BlackFin architectures.</li>
451<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
452 enables support for <a href="LinkTimeOptimization.html">transparent
453 link-time optimization</a> on ELF targets when used with the Gold binutils
454 linker.</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]455<li>LLVM now supports doing optimization and code generation on multiple
456 threads. Please see the <a href="ProgrammersManual.html#threading">LLVM
457 Programmer's Manual</a> for more information.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]458<li>LLVM now has experimental support for <a
459 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
460 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
461 final and the .bc file format may change in future releases. Debug info
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]462 does not yet use this format in LLVM 2.6.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]463</ul>
464
465</div>
466
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]467<!--=========================================================================-->
468<div class="doc_subsection">
469<a name="coreimprovements">LLVM IR and Core Improvements</a>
470</div>
471
472<div class="doc_text">
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]473<p>LLVM IR has several new features for better support of new targets and that
474expose new optimization opportunities:</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]475
476<ul>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]477<li>The <a href="LangRef.html#i_add">add</a>, <a
478 href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
479 instructions have been split into integer and floating point version (like
480 divide and remainder), introducing new <a
481 href="LangRef.html#i_fadd">fadd</a>, <a href="LangRef.html#i_fsub">fsub</a>,
482 and <a href="LangRef.html#i_fmul">fmul</a> instructions.</li>
483<li>The <a href="LangRef.html#i_add">add</a>, <a
484 href="LangRef.html#i_sub">sub</a>, and <a href="LangRef.html#i_mul">mul</a>
485 instructions now support optional "nsw" and "nuw" bits which indicate that
486 the operation is guaranteed to not overflow (in the signed or
487 unsigned case, respectively). This gives the optimizer more information and
488 can be used for things C signed integer values, which are undefined on
489 overflow.</li>
490<li>The <a href="LangRef.html#i_sdiv">sdiv</a> instruction now supports an
491 optional "exact" flag which indicates that the result of the division is
492 guaranteed to have a remainder of zero. This is useful to optimize pointer
493 subtraction in C.</li>
494<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
495 supports arbitrary integer index values for array/pointer indices. This
496 allows for better better code generation on 16-bit targets like PIC16.</li>
497<li>The <a href="LangRef.html#i_getelementptr">getelementptr</a> instruction now
498 supports an "inbounds" optimization hint that tells the optimizer that the
499 pointer is guaranteed to be within its allocated object.</li>
500<li>LLVM now support a series of new linkage types for global values which allow
501 for better optimization and new capabilities:
502 <ul>
503 <li><a href="LangRef.html#linkage_linkonce">linkonce_odr</a> and
504 <a href="LangRef.html#linkage_weak">weak_odr</a> have the same linkage
505 semantics as the non-"odr" linkage types. The difference is that these
506 linkage types indicate that all definitions of the specified function
507 are guaranteed to have the same semantics. This allows inlining
508 templates functions in C++ but not inlining weak functions in C,
509 which previously both got the same linkage type.</li>
510 <li><a href="LangRef.html#linkage_available_externally">available_externally
511 </a> is a new linkage type that gives the optimizer visibility into the
512 definition of a function (allowing inlining and side effect analysis)
513 but that does not cause code to be generated. This allows better
514 optimization of "GNU inline" functions, extern templates, etc.</li>
515 <li><a href="LangRef.html#linkage_linker_private">linker_private</a> is a
516 new linkage type (which is only useful on Mac OS X) that is used for
517 some metadata generation and other obscure things.</li>
518 </ul></li>
519<li>Finally, target-specific intrinsics can now return multiple values, which
520 is useful for modeling target operations with multiple results.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]521</ul>
522
523</div>
524
525<!--=========================================================================-->
526<div class="doc_subsection">
527<a name="optimizer">Optimizer Improvements</a>
528</div>
529
530<div class="doc_text">
531
532<p>In addition to a large array of bug fixes and minor performance tweaks, this
533release includes a few major enhancements and additions to the optimizers:</p>
534
535<ul>
536
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]537<li>SRoA improvements for vector unions, memset, arbitrary weird bitfield accesses etc. It now produces "strange" sized integers.</li>
538<li>Inliner reuse stack space when inlining arrays?</li>
539<li>Enabled GVN Load PRE.</li>
540<li>New Static Single Information (SSI) construction pass (not used by anything yet, experimental).</li>
Chris Lattner4d91d4d2009-10-10 18:33:13 +0000[diff] [blame]541<li>LSR promotes int induction variables to 64-bit on 64-bit targets, major perf boost for numerical code.</li>
542<li>LSR now analyzes pointer expressions (e.g. getelementptrs), not just integers.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]543</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]544
545</ul>
546
547</div>
548
549<!--=========================================================================-->
550<div class="doc_subsection">
551<a name="codegen">Target Independent Code Generator Improvements</a>
552</div>
553
554<div class="doc_text">
555
556<p>We have put a significant amount of work into the code generator
557infrastructure, which allows us to implement more aggressive algorithms and make
558it run faster:</p>
559
560<ul>
561
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]562<li> -asm-verbose now prints location info (with -g) and loop nest info.</li>
563<li>Tblgen now supports multiclass inheritance and a number of new string and
564 list operations like !(subst), !(foreach), !car, !cdr, !null, !if, !cast.
565 These make the .td files more expressive and allow more aggressive factoring
566 of duplication across instruction patterns.</li>
567<li>New MachineVerifier pass.</li>
568<li>Machine LICM, hoists things like constant pool loads, loads from readonly stubs, vector constant synthesization code, etc.</li>
569<li>Machine Sinking</li>
570<li>target-specific intrinsics (r63765)</li>
571<li>Regalloc improvements for commuting, various spiller peephole optimizations, cross-class coalescing.</li>
572<li><tt>llc -enable-value-prop</tt>, propagation of value info (sign/zero ext info) from one MBB to another</li>
573<li>Regalloc hints for allocation stuff: Evan r73381/r73671. Finished/enabled?</li>
574<li>Stack slot coloring for register spills (denser stack frames)</li>
575<li>SelectionDAGS: New BuildVectorSDNode (r65296), and ISD::VECTOR_SHUFFLE (r69952 / PR2957)</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]576<li>Experimental support for shrink wrapping support in PEI.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]577<li>Experimental support for writing ELF .o files directly from the compiler,
578 it works well for many simple C testcases, but doesn't support exception
579 handling, debug info, inline assembly, etc.</li>
580<li>Targets can now specify register allocation hints through
581 MachineRegisterInfo:: setRegAllocationHint. A regalloc hint consists 1) hint
582 type, 2) physical register number. A hint type of zero specifies a register
583 allocation preference. Other hint type values are target specific which are
584 resolved by TargetRegisterInfo::ResolveRegAllocHint. An example of which is
585 the ARM target can uses register hint to request that the register allocator
586 provide an even / odd register pair to two virtual registers. It is
587 important to note the register allocation hints are just hints. There is no
588 guarantee the register allocators will be able to satisfy the hints.</li>
589
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]590</ul>
591</div>
592
593<!--=========================================================================-->
594<div class="doc_subsection">
595<a name="x86">X86-32 and X86-64 Target Improvements</a>
596</div>
597
598<div class="doc_text">
599<p>New features of the X86 target include:
600</p>
601
602<ul>
603
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]604<li>Preliminary support for addrspace 256 -> GS, 257 -> FS, known problems: CodeGenerator.html#x86_memory</li>
605<li>Support for softfloat modes, typically used by OS kernels.</li>
606
607<li>X86-64: better modeling of implicit zero extensions, eliminates a lot of redundant zexts</li>
608<li>X86-64 TLS support for local exec and initial exec.</li>
609<li>Better modeling of H registerts as subregs.</li>
610<li>Vector icmp/fcmp now work with SSE codegen.</li>
611<li>SSE 4.2 support.</li>
612<li>all global variable reference logic is now in ClassifyGlobalReference.</li>
613</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]614</ul>
615
616</div>
617
618<!--=========================================================================-->
619<div class="doc_subsection">
620<a name="pic16">PIC16 Target Improvements</a>
621</div>
622
623<div class="doc_text">
624<p>New features of the PIC16 target include:
625</p>
626
627<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]628<li>Support for floating-point, indirect function calls, and
629 passing/returning aggregate types to functions.
630<li>The code generator is able to generate debug info into output COFF files.
631<li>Support for placing an object into a specific section or at a specific
632 address in memory.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]633</ul>
634
635<p>Things not yet supported:</p>
636
637<ul>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]638<li>Variable arguments.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]639<li>Interrupts/programs.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]640</ul>
641
642</div>
643
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]644<!--=========================================================================-->
645<div class="doc_subsection">
646<a name="ARM">ARM Target Improvements</a>
647</div>
648
649<div class="doc_text">
650<p>New features of the ARM target include:
651</p>
652
653<ul>
654
655<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel16eac042009-08-20 15:01:16 +0000[diff] [blame]656that implement version v7-A of the ARM architecture. The ARM backend now
657supports both the Thumb2 and Advanced SIMD (Neon) instruction sets. The
658AAPCS-VFP "hard float" calling conventions are also supported with the
659<tt>-float-abi=hard</tt> flag. These features are still somewhat experimental
660and subject to change. The Neon intrinsics, in particular, may change in future
661releases of LLVM.
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]662</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]663
664 ARM AAPCS-VFP hard float ABI is supported.
665 ARM calling convention code is now tblgen generated instead of manual.
666 ARM: NEON support. neonfp for doing single precision fp with neon instead of VFP.
667
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]668</ul>
669
670</div>
671
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]672<!--=========================================================================-->
673<div class="doc_subsection">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]674<a name="OtherTarget">Other Target Specific Improvements</a>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]675</div>
676
677<div class="doc_text">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]678<p>New features of other targets include:
679</p>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]680
681<ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]682<li>Mips now supports O32 Calling Convention.</li>
Chris Lattner896d2582009-10-09 06:36:25 +0000[diff] [blame]683<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
684 support, lots of bugs fixed.</li>
685<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
686 Needs more testing.</li>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]687</ul>
688
689</div>
690
691<!--=========================================================================-->
692<div class="doc_subsection">
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]693<a name="executionengine">Interpreter and JIT Improvements</a>
694</div>
695
696<div class="doc_text">
697
698<ul>
699<li>The JIT now supports generating more than 16M of code.</li>
700<li>When configured with --with-oprofile, the JIT can now inform oprofile about
701 JIT'd code, allowing oprofile to get line number and function name
702 information for JIT'd functions.</li>
703<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
704 calling almost arbitrary external (natively compiled) functions.</li>
705<li>Clients of the JIT can now register a 'JITEventListener' object to receive
706 callbacks when the JIT emits or frees machine code. The OProfile support
707 uses this mechanism.</li>
708</ul>
709
710</div>
711
712
713<!--=========================================================================-->
714<div class="doc_subsection">
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]715<a name="newapis">New Useful APIs</a>
716</div>
717
718<div class="doc_text">
719
720<ul>
721<li>New EngineBuilder class for creating JITs: r76276</li>
722 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.
723 StringRef class, Twine class.
724 New WeakVH and AssertingVH and CallbackVH classes.
725 New llvm/ADT/Triple class.
726 llvm_report_error() error handling API (llvm/Support/ErrorHandling.h)
727 New llvm/System/Atomic.h, llvm/System/RWMutex.h for portable atomic ops, rw locks.
728 New SourceMgr, SMLoc classes for simple parsers with caret diagnostics and #include support, (used by
729 tablegen, llvm-mc, the .ll parser, FileCheck, etc)
730
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]731</ul>
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]732
733
734</div>
735
736<!--=========================================================================-->
737<div class="doc_subsection">
738<a name="otherimprovements">Other Improvements and New Features</a>
739</div>
740
741<div class="doc_text">
742<p>Other miscellaneous features include:</p>
743
744<ul>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]745<li>LLVM now includes a new internal '<a
746 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
747 writing much more accurate regression tests that run faster. Please see the
748 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
749 Guide</a> for more information.</li>
Chris Lattner6e6d33c2009-10-09 05:55:04 +0000[diff] [blame]750<li>LLVM profile information support has been significantly improved to produce
751correct use counts, and has support for edge profiling with reduced runtime
752overhead. Combined, the generated profile information is both more correct and
753imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
754CPU2000).</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]755<li>Many extensions to the C APIs.</li>
Chris Lattner0d6011062009-10-09 06:24:25 +0000[diff] [blame]756<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
757programming language.</li>
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]758
759<li>LLVMC:
760
761* Dynamic plugins now work on Windows.
762* New option property: init. Makes possible to provide default values for
763 options defined in plugins (interface to cl::init).
764* New example: Skeleton, shows how to create a standalone LLVMC-based driver.
765* New example: mcc16, a driver for the PIC16 toolchain.</li>
766
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]767</ul>
768
769</div>
770
771
772<!--=========================================================================-->
773<div class="doc_subsection">
774<a name="changes">Major Changes and Removed Features</a>
775</div>
776
777<div class="doc_text">
778
779<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]780on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]781from the previous release.</p>
782
783<ul>
784
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]785<li>The Itanium (IA64) backend has been removed. It was not supported and
786 bitrotted.</li>
787<li>The BigBlock register allocator has been removed, it also bitrotted.</li>
788<li>The C Backend (-march=c) is no longer considered part of the LLVM release
789criteria. We still want it to work, but no one is maintaining it and it lacks
790support for arbitrary precision integers and other important IR features.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]791</ul>
792
Chris Lattner169c7012009-10-08 07:01:46 +0000[diff] [blame]793 LLVM build now builds all libraries as .a files instead of some
794 libraries as relinked .o files. This requires some APIs like
795 InitializeAllTargets.h. TargetRegistry!
796
797
798
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]799
800<p>In addition, many APIs have changed in this release. Some of the major LLVM
801API changes are:</p>
802
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]803
804 API Cleanup:
805 no use of hash_set/hash_map, no more llvm::OStream
806 Use raw_ostream for everything, killed off llvm/Streams.h and DOUT
807
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]808<ul>
Owen Andersonbe3fe4e2009-07-02 16:48:38 +0000[diff] [blame]809<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
810 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
811 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
812 for clients that will only ever use a single context, the new
813 <tt>getGlobalContext()</tt> API can be used to access a default global
814 context which can be passed in any and all cases where a context is
815 required.
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]816<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohman79537c92009-07-07 20:05:15 +0000[diff] [blame]817<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
818 overloaded for floating-point types. Floating-point addition, subtraction,
819 and multiplication are now represented with new operators <tt>FAdd</tt>,
820 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
821 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
822 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
823 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
824 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbara7d9e052009-07-12 20:41:27 +0000[diff] [blame]825<li>The DynamicLibrary class can no longer be constructed, its functionality has
826 moved to static member functions.</li>
Dan Gohmanb6b11702009-07-15 19:59:19 +0000[diff] [blame]827<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
828 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
829 <tt>false</tt>, an error will be reported if a file with the given name
830 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
831 be silently truncated (which is the behavior before this flag was
832 added).</li>
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]833<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
834longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
835used.</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]836
Daniel Dunbare3572ba2009-07-25 04:41:11 +0000[diff] [blame]837<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
838and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
839or <tt>std::string</tt>, as described in
840the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]841clients 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:
842 <ul>
843 <li><tt>getNameStr()</tt> is still available, and matches the old
844 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
845 although more efficient alternatives are now possible.</li>
846
847 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
848 a <tt>std::ostream</tt>, consider migrating
849 to <tt>llvm::raw_ostream</tt>.</li>
850
851 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
852 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
853 Note that this string (as before), may not be the entire name if the
854 name containts embedded null characters.</li>
855
856 <li>If you were using operator plus on the result of <tt>getName()</tt> and
857 treating the result as an <tt>std::string</tt>, you can either
858 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
859 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbare03513b2009-07-25 23:55:21 +0000[diff] [blame]860
861 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramer7b2136d2009-08-05 15:42:44 +0000[diff] [blame]862 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]863 </ul>
864</li>
865
Daniel Dunbar48224ee2009-07-26 02:12:58 +0000[diff] [blame]866<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbarc9a70092009-07-26 05:41:39 +0000[diff] [blame]867previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
868 <ul>
869 <li><tt>TargetMachineRegistry</tt> has been renamed
870 to <tt>TargetRegistry</tt>.</li>
871
872 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
873 function to find targets.</li>
874 </ul>
875</li>
Daniel Dunbarbbfb87a2009-07-25 05:26:53 +0000[diff] [blame]876
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]877<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbare3572ba2009-07-25 04:41:11 +0000[diff] [blame]878FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
879This is not an API change, maybe there should be a tool changes section?</li>
Edwin Török07768e22009-07-21 20:27:10 +0000[diff] [blame]880<li>temporarely due to Context API change passes should call doInitialization()
881method of the pass they inherit from, otherwise Context is NULL.
882FIXME: remove this entry when this is no longer needed.<li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]883</ul>
884
885</div>
886
887
888
889<!-- *********************************************************************** -->
890<div class="doc_section">
891 <a name="portability">Portability and Supported Platforms</a>
892</div>
893<!-- *********************************************************************** -->
894
895<div class="doc_text">
896
897<p>LLVM is known to work on the following platforms:</p>
898
899<ul>
900<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]901Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]902<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
903and 64-bit modes.</li>
904<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
905<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
906 support is available for native builds with Visual C++).</li>
907<li>Sun UltraSPARC workstations running Solaris 10.</li>
908<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]909</ul>
910
911<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
912to the machine and operating system on which it is built. However, minor
913porting may be required to get LLVM to work on new platforms. We welcome your
914portability patches and reports of successful builds or error messages.</p>
915
916</div>
917
918<!-- *********************************************************************** -->
919<div class="doc_section">
920 <a name="knownproblems">Known Problems</a>
921</div>
922<!-- *********************************************************************** -->
923
924<div class="doc_text">
925
926<p>This section contains significant known problems with the LLVM system,
927listed by component. If you run into a problem, please check the <a
928href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
929there isn't already one.</p>
930
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]931<ul>
Chris Lattner4050d252009-07-21 23:17:26 +0000[diff] [blame]932<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]933using the stock GCC 3.x.x series 'out the box',
934See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
935However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
936for x86/x64 has been made available from the third party AuroraUX Project
Chris Lattner6aaf6902009-10-08 06:27:53 +0000[diff] [blame]937that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]938</ul>
939
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]940</div>
941
942<!-- ======================================================================= -->
943<div class="doc_subsection">
944 <a name="experimental">Experimental features included with this release</a>
945</div>
946
947<div class="doc_text">
948
949<p>The following components of this LLVM release are either untested, known to
950be broken or unreliable, or are in early development. These components should
951not be relied on, and bugs should not be filed against them, but they may be
952useful to some people. In particular, if you would like to work on one of these
953components, please contact us on the <a
954href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
955
956<ul>
Dan Gohman2a5ddf32009-07-24 00:30:09 +0000[diff] [blame]957<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]958<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
959 supported value for this option.</li>
960</ul>
961
962</div>
963
964<!-- ======================================================================= -->
965<div class="doc_subsection">
966 <a name="x86-be">Known problems with the X86 back-end</a>
967</div>
968
969<div class="doc_text">
970
971<ul>
972 <li>The X86 backend does not yet support
973 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
974 floating point stack</a>. It supports the 'f' and 't' constraints, but not
975 'u'.</li>
976 <li>The X86 backend generates inefficient floating point code when configured
977 to generate code for systems that don't have SSE2.</li>
978 <li>Win64 code generation wasn't widely tested. Everything should work, but we
979 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
980 runtime currently due
981 to <a href="http://llvm.org/PR2255">several</a>
982 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
983 the
984 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
985 <li>The X86-64 backend does not yet support the LLVM IR instruction
986 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
987 argument constructs on X86-64 by lowering them manually.</li>
988</ul>
989
990</div>
991
992<!-- ======================================================================= -->
993<div class="doc_subsection">
994 <a name="ppc-be">Known problems with the PowerPC back-end</a>
995</div>
996
997<div class="doc_text">
998
999<ul>
1000<li>The Linux PPC32/ABI support needs testing for the interpreter and static
1001compilation, and lacks support for debug information.</li>
1002</ul>
1003
1004</div>
1005
1006<!-- ======================================================================= -->
1007<div class="doc_subsection">
1008 <a name="arm-be">Known problems with the ARM back-end</a>
1009</div>
1010
1011<div class="doc_text">
1012
1013<ul>
Bob Wilson80333842009-08-12 21:19:49 +0000[diff] [blame]1014<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
1015and not well tested. Some features may not work at all, and the code quality
1016may be poor in some cases.</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1017<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
1018processors, thumb programs can crash or produce wrong
1019results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
1020<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
1021</li>
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1022</ul>
1023
1024</div>
1025
1026<!-- ======================================================================= -->
1027<div class="doc_subsection">
1028 <a name="sparc-be">Known problems with the SPARC back-end</a>
1029</div>
1030
1031<div class="doc_text">
1032
1033<ul>
1034<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
1035 support the 64-bit SPARC ABI (-m64).</li>
1036</ul>
1037
1038</div>
1039
1040<!-- ======================================================================= -->
1041<div class="doc_subsection">
1042 <a name="mips-be">Known problems with the MIPS back-end</a>
1043</div>
1044
1045<div class="doc_text">
1046
1047<ul>
1048<li>The O32 ABI is not fully supported.</li>
1049<li>64-bit MIPS targets are not supported yet.</li>
1050</ul>
1051
1052</div>
1053
1054<!-- ======================================================================= -->
1055<div class="doc_subsection">
1056 <a name="alpha-be">Known problems with the Alpha back-end</a>
1057</div>
1058
1059<div class="doc_text">
1060
1061<ul>
1062
1063<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1064appropriate nops inserted to ensure restartability.</li>
1065
1066</ul>
1067</div>
1068
1069<!-- ======================================================================= -->
1070<div class="doc_subsection">
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1071 <a name="c-be">Known problems with the C back-end</a>
1072</div>
1073
1074<div class="doc_text">
1075
1076<ul>
1077<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1078 inline assembly code</a>.</li>
1079<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1080 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1081 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1082<li>The C backend does not support all exception handling constructs.</li>
1083<li>The C backend does not support arbitrary precision integers.</li>
1084</ul>
1085
1086</div>
1087
1088
1089<!-- ======================================================================= -->
1090<div class="doc_subsection">
1091 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
1092</div>
1093
1094<div class="doc_text">
1095
1096<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
1097Optimization</a> on most platforms "out-of-the-box". Please inquire on the
1098LLVMdev mailing list if you are interested.</p>
1099
1100<p>The only major language feature of GCC not supported by llvm-gcc is
1101 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1102 are only supported on some targets. For example, trampolines are only
1103 supported on some targets (these are used when you take the address of a
1104 nested function).</p>
1105
1106<p>If you run into GCC extensions which are not supported, please let us know.
1107</p>
1108
1109</div>
1110
1111<!-- ======================================================================= -->
1112<div class="doc_subsection">
1113 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
1114</div>
1115
1116<div class="doc_text">
1117
1118<p>The C++ front-end is considered to be fully
1119tested and works for a number of non-trivial programs, including LLVM
1120itself, Qt, Mozilla, etc.</p>
1121
1122<ul>
1123<li>Exception handling works well on the X86 and PowerPC targets. Currently
1124 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
1125</ul>
1126
1127</div>
1128
1129<!-- ======================================================================= -->
1130<div class="doc_subsection">
1131 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1132</div>
1133
1134<div class="doc_text">
1135<ul>
1136<li>Fortran support generally works, but there are still several unresolved bugs
1137 in Bugzilla. Please see the tools/gfortran component for details.</li>
1138</ul>
1139</div>
1140
1141<!-- ======================================================================= -->
1142<div class="doc_subsection">
1143 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1144</div>
1145
1146<div class="doc_text">
1147The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1148technology, and problems should be expected.
1149<ul>
1150<li>The Ada front-end currently only builds on X86-32. This is mainly due
1151to lack of trampoline support (pointers to nested functions) on other platforms.
1152However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1153which does support trampolines.</li>
1154<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1155This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1156exception handling, which is used internally by the compiler.
1157Workaround: configure with --disable-bootstrap.</li>
1158<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1159and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1160(c380004 also fails with gcc-4.2 mainline).
1161If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1162causes the compiler to go into an infinite loop, using up all system memory.</li>
1163<li>Some GCC specific Ada tests continue to crash the compiler.</li>
1164<li>The -E binder option (exception backtraces)
1165<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1166crashing if an exception is raised. Workaround: do not use -E.</li>
1167<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1168or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1169or use representation clauses that result in a field of a non-discrete type
1170starting or finishing in the middle of a byte.</li>
1171<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1172'main' as generated by the Ada binder to be invalid</a>.
1173Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1174<tt>envp</tt> rather than integers.</li>
1175<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1176ignored</a>.</li>
1177</ul>
1178</div>
1179
Erick Tryzelaarb4cf9752009-09-28 04:42:55 +0000[diff] [blame]1180<!-- ======================================================================= -->
1181<div class="doc_subsection">
1182 <a name="ocaml-bindingse">Known problems with the O'Caml bindings</a>
1183</div>
1184
1185<div class="doc_text">
1186
1187<p>The Llvm.Linkage module is broken, and has incorrect values. Only
1188Llvm.Linkage.External, Llvm.Linkage.Available_externally, and
1189Llvm.Linkage.Link_once will be correct. If you need any of the other linkage
1190modes, you'll have to write an external C library in order to expose the
1191functionality. This has been fixed in the trunk.</p>
1192</div>
1193
Duncan Sands54fbb412009-06-24 08:38:48 +0000[diff] [blame]1194<!-- *********************************************************************** -->
1195<div class="doc_section">
1196 <a name="additionalinfo">Additional Information</a>
1197</div>
1198<!-- *********************************************************************** -->
1199
1200<div class="doc_text">
1201
1202<p>A wide variety of additional information is available on the <a
1203href="http://llvm.org">LLVM web page</a>, in particular in the <a
1204href="http://llvm.org/docs/">documentation</a> section. The web page also
1205contains versions of the API documentation which is up-to-date with the
1206Subversion version of the source code.
1207You can access versions of these documents specific to this release by going
1208into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1209
1210<p>If you have any questions or comments about LLVM, please feel free to contact
1211us via the <a href="http://llvm.org/docs/#maillist"> mailing
1212lists</a>.</p>
1213
1214</div>
1215
1216<!-- *********************************************************************** -->
1217
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