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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 Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]54
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]55
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]56<!--
57Almost dead code.
Chris Lattner80ed2552009-10-08 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 Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]61-->
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]62
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]63
64<!-- Unfinished features in 2.6:
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]65 gcc plugin.
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]66 strong phi elim
67 variable debug info for optimized code
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]68 postalloc scheduler: anti dependence breaking, hazard recognizer?
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]69 metadata
70 loop dependence analysis
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]71 ELF Writer? How stable?
72 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]73 2.7 supports the GDB 7.0 jit interfaces for debug info.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]74 -->
75
76 <!-- for announcement email:
Chris Lattnerc758fec2009-10-05 02:12:39 +0000[diff] [blame]77 Logo web page.
78 llvm devmtg
79 compiler_rt
Chris Lattner7b0a6812009-10-08 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 Sandse2e4a892009-06-24 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
95repository &mdash;which roughly includes the LLVM optimizers, code generators
96and supporting tools &mdash; and the llvm-gcc repository. In addition to this
97code, the LLVM Project includes other sub-projects that are in development. The
98two which are the most actively developed are the <a href="#clang">Clang
99Project</a> and the <a href="#vmkit">VMKit Project</a>.
100</p>
101
102</div>
103
104
105<!--=========================================================================-->
106<div class="doc_subsection">
107<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
108</div>
109
110<div class="doc_text">
111
Chris Lattner28d02742009-10-09 05:01:15 +0000[diff] [blame]112<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
113a set of new 'LLVM native' front-end technologies for the C family of languages.
114LLVM 2.6 is the first release to officially include Clang, and it provides a
115production quality C and Objective-C compiler. If you are interested in fast
116compiles and good diagnostics, we encourage you to try it out.</p>
117
118<p>In addition to supporting these languages, C++ support is also <a
119href="http://clang.llvm.org/cxx_status.html">well under way</a>, and mainline
120Clang is able to parse the libstdc++ 4.2 headers and even codegen simple apps.
121If you are interested in Clang C++ support or any other Clang feature, we
122strongly encourage you to get involved on the <a
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]123href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
124list</a>.</p>
125
126<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
127
128<ul>
Chris Lattner28d02742009-10-09 05:01:15 +0000[diff] [blame]129<li>C and Objective-C support are now considered production quality.</li>
Chris Lattnerc32a5322009-09-30 06:27:22 +0000[diff] [blame]130<li>AuroraUX / FreeBSD &amp; OpenBSD Toolchain support.</li>
Chris Lattner28d02742009-10-09 05:01:15 +0000[diff] [blame]131<li>Most of Objective-C 2.0 is now supported with the GNU runtime.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]132<li>Many many bugs are fixed and many features have been added.</li>
133</ul>
134</div>
135
136<!--=========================================================================-->
137<div class="doc_subsection">
138<a name="clangsa">Clang Static Analyzer</a>
139</div>
140
141<div class="doc_text">
142
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]143<p><b>UPDATE!</b> Previously announced in the 2.4 and 2.5 LLVM releases, the Clang project also
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]144includes an early stage static source code analysis tool for <a
145href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
146in C and Objective-C programs. The tool performs a growing set of checks to find
147bugs that occur on a specific path within a program.</p>
148
149<p>In the LLVM 2.6 time-frame there have been many significant improvements to
150XYZ.</p>
151
152<p>The set of checks performed by the static analyzer continues to expand, and
153future plans for the tool include full source-level inter-procedural analysis
154and deeper checks such as buffer overrun detection. There are many opportunities
155to extend and enhance the static analyzer, and anyone interested in working on
156this project is encouraged to get involved!</p>
157
158</div>
159
160<!--=========================================================================-->
161<div class="doc_subsection">
162<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
163</div>
164
165<div class="doc_text">
166<p>
167The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
Nicolas Geoffraye83ae232009-10-09 10:13:08 +0000[diff] [blame]168a JVM and a CLI Virtual Machine (Microsoft .NET is an
Nicolas Geoffray7b2e71b2009-10-09 10:17:14 +0000[diff] [blame]169implementation of the CLI) using LLVM for static and just-in-time
170compilation.</p>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]171
Nicolas Geoffray7b2e71b2009-10-09 10:17:14 +0000[diff] [blame]172<p>
173VMKit version 0.26 builds with LLVM 2.6 and you can find it on its
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]174<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
175bug fixes, cleanup and new features. The major changes are:</p>
176
177<ul>
178
Nicolas Geoffray7b2e71b2009-10-09 10:17:14 +0000[diff] [blame]179<li>A new llcj tool to generate shared libraries or executables of Java
180 files.</li>
Nicolas Geoffray0c536be2009-10-09 13:17:57 +0000[diff] [blame]181<li>Cooperative garbage collection. </li>
Nicolas Geoffraye83ae232009-10-09 10:13:08 +0000[diff] [blame]182<li>Fast subtype checking (paper from Click et al [JGI'02]). </li>
Nicolas Geoffray7b2e71b2009-10-09 10:17:14 +0000[diff] [blame]183<li>Implementation of a two-word header for Java objects instead of the orginal
184 three-word header. </li>
185<li>Better Java specification-compliance: division by zero checks, stack
186 overflow checks, finalization and references support. </li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]187
188</ul>
189</div>
190
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]191
192<!--=========================================================================-->
193<div class="doc_subsection">
194<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
195</div>
196
197<div class="doc_text">
198<p>
199The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
200is a simple library that provides an implementation of the low-level
201target-specific hooks required by code generation and other runtime components.
202For example, when compiling for a 32-bit target, converting a double to a 64-bit
203unsigned integer is compiling into a runtime call to the "__fixunsdfdi"
204function. The compiler-rt library provides optimized implementations of this and
205other low-level routines.</p>
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">
215<a name="klee">klee: Symbolic Execution and Automatic Test Case Generator</a>
216</div>
217
218<div class="doc_text">
219<p>
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
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
227Klee.</p>
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 Lattner80ed2552009-10-08 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 Lattner45178502009-10-09 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 Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]260
Chris Lattner45178502009-10-09 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 Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]274</p>
275
276</div>
277
278
Duncan Sandse2e4a892009-06-24 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 Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]285<!--=========================================================================-->
286<div class="doc_subsection">
287<a name="Rubinius">Rubinius</a>
288</div>
289
290<div class="doc_text">
291<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
292for running Ruby code which strives to write as much of the core class
293implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
294uses LLVM to optimize and compile ruby code down to machine code. Techniques
295such as type feedback, method inlining, and uncommon traps are all used to
296remove dynamism from ruby execution and increase performance.</p>
Chris Lattnerd4a537b2009-10-08 16:01:33 +0000[diff] [blame]297
298<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
299a counter based JIT, type feedback, and speculative method inlining.
300</p>
301
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]302</div>
Chris Lattnerc32a5322009-09-30 06:27:22 +0000[diff] [blame]303
304<!--=========================================================================-->
305<div class="doc_subsection">
306<a name="macruby">MacRuby</a>
307</div>
308
309<div class="doc_text">
310
311<p>
312<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
313core Mac OS X technologies, such as the Objective-C common runtime and garbage
314collector, and the CoreFoundation framework. It is principally developed by
315Apple and aims at enabling the creation of full-fledged Mac OS X applications.
316</p>
317
318<p>
319MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
320expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
321handling.</p>
322
323</div>
324
325
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]326<!--=========================================================================-->
327<div class="doc_subsection">
328<a name="pure">Pure</a>
329</div>
330
331<div class="doc_text">
332<p>
333<a href="http://pure-lang.googlecode.com/">Pure</a>
334is an algebraic/functional programming language based on term rewriting.
335Programs are collections of equations which are used to evaluate expressions in
336a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
337lexical closures, a hygienic macro system (also based on term rewriting),
338built-in list and matrix support (including list and matrix comprehensions) and
339an easy-to-use C interface. The interpreter uses LLVM as a backend to
340 JIT-compile Pure programs to fast native code.</p>
341
Chris Lattnerd4a537b2009-10-08 16:01:33 +0000[diff] [blame]342<p>Pure versions 0.31 and later have been tested and are known to work with
343LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]344</p>
345</div>
346
347
348<!--=========================================================================-->
349<div class="doc_subsection">
350<a name="ldc">LLVM D Compiler</a>
351</div>
352
353<div class="doc_text">
354<p>
355<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
356the D Programming Language using the LLVM optimizer and code generator.
357The LDC project works great with the LLVM 2.6 release. General improvements in
358this
359cycle have included new inline asm constraint handling, better debug info
360support, general bugfixes, and better x86-64 support. This has allowed
361some major improvements in LDC, getting us much closer to being as
362fully featured as the original DMD compiler from DigitalMars.
363</p>
364</div>
365
366<!--=========================================================================-->
367<div class="doc_subsection">
368<a name="RoadsendPHP">Roadsend PHP</a>
369</div>
370
371<div class="doc_text">
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]372<p>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]373<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]374source implementation of the PHP programming
375language that uses LLVM for its optimizer, JIT, and static compiler. This is a
376reimplementation of an earlier project that is now based on LLVM.</p>
377</div>
378
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]379<!--=========================================================================-->
380<div class="doc_subsection">
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]381<a name="UnladenSwallow">Unladen Swallow</a>
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]382</div>
383
384<div class="doc_text">
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]385<p>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]386<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]387branch of <a href="http://python.org/">Python</a> intended to be fully
388compatible and significantly faster. It uses LLVM's optimization passes and JIT
389compiler.</p>
390</div>
391
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]392<!--=========================================================================-->
393<div class="doc_subsection">
394<a name="llvm-lua">llvm-lua</a>
395</div>
396
397<div class="doc_text">
398<p>
399<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
400&amp; static compiling support to the Lua VM. Lua bytecode is analyzed to
401remove type checks, then LLVM is used to compile those bytecodes down to machine
402code.</p>
403</div>
404
Jeffrey Yasskin5e98cb72009-06-24 21:26:42 +0000[diff] [blame]405
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]406
407<!-- *********************************************************************** -->
408<div class="doc_section">
409 <a name="whatsnew">What's New in LLVM 2.6?</a>
410</div>
411<!-- *********************************************************************** -->
412
413<div class="doc_text">
414
415<p>This release includes a huge number of bug fixes, performance tweaks, and
416minor improvements. Some of the major improvements and new features are listed
417in this section.
418</p>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]419
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]420</div>
421
422<!--=========================================================================-->
423<div class="doc_subsection">
424<a name="majorfeatures">Major New Features</a>
425</div>
426
427<div class="doc_text">
428
429<p>LLVM 2.6 includes several major new capabilities:</p>
430
431<ul>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]432<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">klee</a>,
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]433 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
434<li>Debug information now includes line numbers when optimizations are enabled.
435 This allows statistical sampling tools like oprofile and Shark to map
436 samples back to source lines.</li>
437<li>LLVM now includes new experimental backends to support the MSP430, SystemZ,
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]438 and BlackFin architectures.</li>
439<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
440 enables support for <a href="LinkTimeOptimization.html">transparent
441 link-time optimization</a> on ELF targets when used with the Gold binutils
442 linker.</li>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]443<li>LLVM now supports doing optimization and code generation on multiple threads
444 by allowing multiple "LLVMContext" objects to exist. Please see the <a
445 href="ProgrammersManual.html#threading">threading entry in the Programmer's
446 Manual</a> for more information.</li>
Chris Lattnera8f42142009-10-09 06:36:25 +0000[diff] [blame]447<li>LLVM now has experimental support for <a
448 href="http://nondot.org/~sabre/LLVMNotes/EmbeddedMetadata.txt">embedded
449 metadata</a> in LLVM IR, though the implementation is not guaranteed to be
450 final and the .bc file format may change in future releases. Debug info
451 does not yet use this format in LLVM 2.6.</p>
452
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]453</ul>
454
455</div>
456
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]457<!--=========================================================================-->
458<div class="doc_subsection">
459<a name="coreimprovements">LLVM IR and Core Improvements</a>
460</div>
461
462<div class="doc_text">
463<p>LLVM IR has several new features that are used by our existing front-ends and
464can be useful if you are writing a front-end for LLVM:</p>
465
466<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]467<li>Getelementpr instruction now allows any integer type for array/pointer indexes.</li>
468<li>Inbounds for GEP</li>
469<li>NSW/NUW/exact div</li>
470<li>LSR promotes int induction variables to 64-bit on 64-bit targets, major perf boost for numerical code.</li>
471<li>LSR now analyzes pointer expressions (e.g. getelementptrs), not just integers.</li>
472<li>new linkage types linkonce_odr, weak_odr, linker_private, and available_externally.</li>
473<li>New fadd, fsub, fmul instructions and classes. </li>
474<li>Target intrinsics can now return multiple results.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]475</ul>
476
477</div>
478
479<!--=========================================================================-->
480<div class="doc_subsection">
481<a name="optimizer">Optimizer Improvements</a>
482</div>
483
484<div class="doc_text">
485
486<p>In addition to a large array of bug fixes and minor performance tweaks, this
487release includes a few major enhancements and additions to the optimizers:</p>
488
489<ul>
490
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]491<li>SRoA improvements for vector unions, memset, arbitrary weird bitfield accesses etc. It now produces "strange" sized integers.</li>
492<li>Inliner reuse stack space when inlining arrays?</li>
493<li>Enabled GVN Load PRE.</li>
494<li>New Static Single Information (SSI) construction pass (not used by anything yet, experimental).</li>
495</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]496
497</ul>
498
499</div>
500
501<!--=========================================================================-->
502<div class="doc_subsection">
503<a name="codegen">Target Independent Code Generator Improvements</a>
504</div>
505
506<div class="doc_text">
507
508<p>We have put a significant amount of work into the code generator
509infrastructure, which allows us to implement more aggressive algorithms and make
510it run faster:</p>
511
512<ul>
513
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]514<li> -asm-verbose now prints location info (with -g) and loop nest info.</li>
515<li>Tblgen now supports multiclass inheritance and a number of new string and
516 list operations like !(subst), !(foreach), !car, !cdr, !null, !if, !cast.
517 These make the .td files more expressive and allow more aggressive factoring
518 of duplication across instruction patterns.</li>
519<li>New MachineVerifier pass.</li>
520<li>Machine LICM, hoists things like constant pool loads, loads from readonly stubs, vector constant synthesization code, etc.</li>
521<li>Machine Sinking</li>
522<li>target-specific intrinsics (r63765)</li>
523<li>Regalloc improvements for commuting, various spiller peephole optimizations, cross-class coalescing.</li>
524<li><tt>llc -enable-value-prop</tt>, propagation of value info (sign/zero ext info) from one MBB to another</li>
525<li>Regalloc hints for allocation stuff: Evan r73381/r73671. Finished/enabled?</li>
526<li>Stack slot coloring for register spills (denser stack frames)</li>
527<li>SelectionDAGS: New BuildVectorSDNode (r65296), and ISD::VECTOR_SHUFFLE (r69952 / PR2957)</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]528<li>Experimental support for shrink wrapping support in PEI.</li>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]529<li>Experimental support for writing ELF .o files directly from the compiler,
530 it works well for many simple C testcases, but doesn't support exception
531 handling, debug info, inline assembly, etc.</li>
532<li>Targets can now specify register allocation hints through
533 MachineRegisterInfo:: setRegAllocationHint. A regalloc hint consists 1) hint
534 type, 2) physical register number. A hint type of zero specifies a register
535 allocation preference. Other hint type values are target specific which are
536 resolved by TargetRegisterInfo::ResolveRegAllocHint. An example of which is
537 the ARM target can uses register hint to request that the register allocator
538 provide an even / odd register pair to two virtual registers. It is
539 important to note the register allocation hints are just hints. There is no
540 guarantee the register allocators will be able to satisfy the hints.</li>
541
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]542</ul>
543</div>
544
545<!--=========================================================================-->
546<div class="doc_subsection">
547<a name="x86">X86-32 and X86-64 Target Improvements</a>
548</div>
549
550<div class="doc_text">
551<p>New features of the X86 target include:
552</p>
553
554<ul>
555
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]556<li>Preliminary support for addrspace 256 -> GS, 257 -> FS, known problems: CodeGenerator.html#x86_memory</li>
557<li>Support for softfloat modes, typically used by OS kernels.</li>
558
559<li>X86-64: better modeling of implicit zero extensions, eliminates a lot of redundant zexts</li>
560<li>X86-64 TLS support for local exec and initial exec.</li>
561<li>Better modeling of H registerts as subregs.</li>
562<li>Vector icmp/fcmp now work with SSE codegen.</li>
563<li>SSE 4.2 support.</li>
564<li>all global variable reference logic is now in ClassifyGlobalReference.</li>
565</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]566</ul>
567
568</div>
569
570<!--=========================================================================-->
571<div class="doc_subsection">
572<a name="pic16">PIC16 Target Improvements</a>
573</div>
574
575<div class="doc_text">
576<p>New features of the PIC16 target include:
577</p>
578
579<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]580<li>Support for floating-point, indirect function calls, and
581 passing/returning aggregate types to functions.
582<li>The code generator is able to generate debug info into output COFF files.
583<li>Support for placing an object into a specific section or at a specific
584 address in memory.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]585</ul>
586
587<p>Things not yet supported:</p>
588
589<ul>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]590<li>Variable arguments.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]591<li>Interrupts/programs.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]592</ul>
593
594</div>
595
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]596<!--=========================================================================-->
597<div class="doc_subsection">
598<a name="ARM">ARM Target Improvements</a>
599</div>
600
601<div class="doc_text">
602<p>New features of the ARM target include:
603</p>
604
605<ul>
606
607<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel64e39612009-08-20 15:01:16 +0000[diff] [blame]608that implement version v7-A of the ARM architecture. The ARM backend now
609supports both the Thumb2 and Advanced SIMD (Neon) instruction sets. The
610AAPCS-VFP "hard float" calling conventions are also supported with the
611<tt>-float-abi=hard</tt> flag. These features are still somewhat experimental
612and subject to change. The Neon intrinsics, in particular, may change in future
613releases of LLVM.
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]614</li>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]615
616 ARM AAPCS-VFP hard float ABI is supported.
617 ARM calling convention code is now tblgen generated instead of manual.
618 ARM: NEON support. neonfp for doing single precision fp with neon instead of VFP.
619
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]620</ul>
621
622</div>
623
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]624<!--=========================================================================-->
625<div class="doc_subsection">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]626<a name="OtherTarget">Other Target Specific Improvements</a>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]627</div>
628
629<div class="doc_text">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]630<p>New features of other targets include:
631</p>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]632
633<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]634<li>Mips now supports O32 Calling Convention.</li>
Chris Lattnera8f42142009-10-09 06:36:25 +0000[diff] [blame]635<li>Many improvements to the 32-bit PowerPC SVR4 ABI (used on powerpc-linux)
636 support, lots of bugs fixed.</li>
637<li>Added support for the 64-bit PowerPC SVR4 ABI (used on powerpc64-linux).
638 Needs more testing.</li>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]639</ul>
640
641</div>
642
643<!--=========================================================================-->
644<div class="doc_subsection">
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]645<a name="executionengine">Interpreter and JIT Improvements</a>
646</div>
647
648<div class="doc_text">
649
650<ul>
651<li>The JIT now supports generating more than 16M of code.</li>
652<li>When configured with --with-oprofile, the JIT can now inform oprofile about
653 JIT'd code, allowing oprofile to get line number and function name
654 information for JIT'd functions.</li>
655<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
656 calling almost arbitrary external (natively compiled) functions.</li>
657<li>Clients of the JIT can now register a 'JITEventListener' object to receive
658 callbacks when the JIT emits or frees machine code. The OProfile support
659 uses this mechanism.</li>
660</ul>
661
662</div>
663
664
665<!--=========================================================================-->
666<div class="doc_subsection">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]667<a name="newapis">New Useful APIs</a>
668</div>
669
670<div class="doc_text">
671
672<ul>
673<li>New EngineBuilder class for creating JITs: r76276</li>
674 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.
675 StringRef class, Twine class.
676 New WeakVH and AssertingVH and CallbackVH classes.
677 New llvm/ADT/Triple class.
678 llvm_report_error() error handling API (llvm/Support/ErrorHandling.h)
679 New llvm/System/Atomic.h, llvm/System/RWMutex.h for portable atomic ops, rw locks.
680 New SourceMgr, SMLoc classes for simple parsers with caret diagnostics and #include support, (used by
681 tablegen, llvm-mc, the .ll parser, FileCheck, etc)
682
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]683</ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]684
685
686</div>
687
688<!--=========================================================================-->
689<div class="doc_subsection">
690<a name="otherimprovements">Other Improvements and New Features</a>
691</div>
692
693<div class="doc_text">
694<p>Other miscellaneous features include:</p>
695
696<ul>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]697<li>LLVM now includes a new internal '<a
698 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
699 writing much more accurate regression tests that run faster. Please see the
700 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
701 Guide</a> for more information.</li>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]702<li>LLVM profile information support has been significantly improved to produce
703correct use counts, and has support for edge profiling with reduced runtime
704overhead. Combined, the generated profile information is both more correct and
705imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
706CPU2000).</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]707<li>Many extensions to the C APIs.</li>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]708<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
709programming language.</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]710
711<li>LLVMC:
712
713* Dynamic plugins now work on Windows.
714* New option property: init. Makes possible to provide default values for
715 options defined in plugins (interface to cl::init).
716* New example: Skeleton, shows how to create a standalone LLVMC-based driver.
717* New example: mcc16, a driver for the PIC16 toolchain.</li>
718
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]719</ul>
720
721</div>
722
723
724<!--=========================================================================-->
725<div class="doc_subsection">
726<a name="changes">Major Changes and Removed Features</a>
727</div>
728
729<div class="doc_text">
730
731<p>If you're already an LLVM user or developer with out-of-tree changes based
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]732on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]733from the previous release.</p>
734
735<ul>
736
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]737<li>The Itanium (IA64) backend has been removed. It was not supported and
738 bitrotted.</li>
739<li>The BigBlock register allocator has been removed, it also bitrotted.</li>
740<li>The C Backend (-march=c) is no longer considered part of the LLVM release
741criteria. We still want it to work, but no one is maintaining it and it lacks
742support for arbitrary precision integers and other important IR features.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]743</ul>
744
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]745 LLVM build now builds all libraries as .a files instead of some
746 libraries as relinked .o files. This requires some APIs like
747 InitializeAllTargets.h. TargetRegistry!
748
749
750
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]751
752<p>In addition, many APIs have changed in this release. Some of the major LLVM
753API changes are:</p>
754
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]755
756 API Cleanup:
757 no use of hash_set/hash_map, no more llvm::OStream
758 Use raw_ostream for everything, killed off llvm/Streams.h and DOUT
759
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]760<ul>
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]761<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
762 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
763 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
764 for clients that will only ever use a single context, the new
765 <tt>getGlobalContext()</tt> API can be used to access a default global
766 context which can be passed in any and all cases where a context is
767 required.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]768<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohmanf667e7e2009-07-07 20:05:15 +0000[diff] [blame]769<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
770 overloaded for floating-point types. Floating-point addition, subtraction,
771 and multiplication are now represented with new operators <tt>FAdd</tt>,
772 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
773 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
774 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
775 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
776 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbar02e73132009-07-12 20:41:27 +0000[diff] [blame]777<li>The DynamicLibrary class can no longer be constructed, its functionality has
778 moved to static member functions.</li>
Dan Gohmane4d54d72009-07-15 19:59:19 +0000[diff] [blame]779<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
780 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
781 <tt>false</tt>, an error will be reported if a file with the given name
782 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
783 be silently truncated (which is the behavior before this flag was
784 added).</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]785<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
786longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
787used.</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]788
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]789<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
790and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
791or <tt>std::string</tt>, as described in
792the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]793clients 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:
794 <ul>
795 <li><tt>getNameStr()</tt> is still available, and matches the old
796 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
797 although more efficient alternatives are now possible.</li>
798
799 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
800 a <tt>std::ostream</tt>, consider migrating
801 to <tt>llvm::raw_ostream</tt>.</li>
802
803 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
804 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
805 Note that this string (as before), may not be the entire name if the
806 name containts embedded null characters.</li>
807
808 <li>If you were using operator plus on the result of <tt>getName()</tt> and
809 treating the result as an <tt>std::string</tt>, you can either
810 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
811 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbar03d76512009-07-25 23:55:21 +0000[diff] [blame]812
813 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramere15192b2009-08-05 15:42:44 +0000[diff] [blame]814 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]815 </ul>
816</li>
817
Daniel Dunbara5881e32009-07-26 02:12:58 +0000[diff] [blame]818<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbard6b06b12009-07-26 05:41:39 +0000[diff] [blame]819previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
820 <ul>
821 <li><tt>TargetMachineRegistry</tt> has been renamed
822 to <tt>TargetRegistry</tt>.</li>
823
824 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
825 function to find targets.</li>
826 </ul>
827</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]828
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]829<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]830FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
831This is not an API change, maybe there should be a tool changes section?</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]832<li>temporarely due to Context API change passes should call doInitialization()
833method of the pass they inherit from, otherwise Context is NULL.
834FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]835</ul>
836
837</div>
838
839
840
841<!-- *********************************************************************** -->
842<div class="doc_section">
843 <a name="portability">Portability and Supported Platforms</a>
844</div>
845<!-- *********************************************************************** -->
846
847<div class="doc_text">
848
849<p>LLVM is known to work on the following platforms:</p>
850
851<ul>
852<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]853Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]854<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
855and 64-bit modes.</li>
856<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
857<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
858 support is available for native builds with Visual C++).</li>
859<li>Sun UltraSPARC workstations running Solaris 10.</li>
860<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]861</ul>
862
863<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
864to the machine and operating system on which it is built. However, minor
865porting may be required to get LLVM to work on new platforms. We welcome your
866portability patches and reports of successful builds or error messages.</p>
867
868</div>
869
870<!-- *********************************************************************** -->
871<div class="doc_section">
872 <a name="knownproblems">Known Problems</a>
873</div>
874<!-- *********************************************************************** -->
875
876<div class="doc_text">
877
878<p>This section contains significant known problems with the LLVM system,
879listed by component. If you run into a problem, please check the <a
880href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
881there isn't already one.</p>
882
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]883<ul>
Chris Lattneraedb59a2009-07-21 23:17:26 +0000[diff] [blame]884<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]885using the stock GCC 3.x.x series 'out the box',
886See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
887However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
888for x86/x64 has been made available from the third party AuroraUX Project
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]889that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]890</ul>
891
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]892</div>
893
894<!-- ======================================================================= -->
895<div class="doc_subsection">
896 <a name="experimental">Experimental features included with this release</a>
897</div>
898
899<div class="doc_text">
900
901<p>The following components of this LLVM release are either untested, known to
902be broken or unreliable, or are in early development. These components should
903not be relied on, and bugs should not be filed against them, but they may be
904useful to some people. In particular, if you would like to work on one of these
905components, please contact us on the <a
906href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
907
908<ul>
Dan Gohmand2cb3d22009-07-24 00:30:09 +0000[diff] [blame]909<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]910<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
911 supported value for this option.</li>
912</ul>
913
914</div>
915
916<!-- ======================================================================= -->
917<div class="doc_subsection">
918 <a name="x86-be">Known problems with the X86 back-end</a>
919</div>
920
921<div class="doc_text">
922
923<ul>
924 <li>The X86 backend does not yet support
925 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
926 floating point stack</a>. It supports the 'f' and 't' constraints, but not
927 'u'.</li>
928 <li>The X86 backend generates inefficient floating point code when configured
929 to generate code for systems that don't have SSE2.</li>
930 <li>Win64 code generation wasn't widely tested. Everything should work, but we
931 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
932 runtime currently due
933 to <a href="http://llvm.org/PR2255">several</a>
934 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
935 the
936 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
937 <li>The X86-64 backend does not yet support the LLVM IR instruction
938 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
939 argument constructs on X86-64 by lowering them manually.</li>
940</ul>
941
942</div>
943
944<!-- ======================================================================= -->
945<div class="doc_subsection">
946 <a name="ppc-be">Known problems with the PowerPC back-end</a>
947</div>
948
949<div class="doc_text">
950
951<ul>
952<li>The Linux PPC32/ABI support needs testing for the interpreter and static
953compilation, and lacks support for debug information.</li>
954</ul>
955
956</div>
957
958<!-- ======================================================================= -->
959<div class="doc_subsection">
960 <a name="arm-be">Known problems with the ARM back-end</a>
961</div>
962
963<div class="doc_text">
964
965<ul>
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]966<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
967and not well tested. Some features may not work at all, and the code quality
968may be poor in some cases.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]969<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
970processors, thumb programs can crash or produce wrong
971results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
972<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
973</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]974</ul>
975
976</div>
977
978<!-- ======================================================================= -->
979<div class="doc_subsection">
980 <a name="sparc-be">Known problems with the SPARC back-end</a>
981</div>
982
983<div class="doc_text">
984
985<ul>
986<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
987 support the 64-bit SPARC ABI (-m64).</li>
988</ul>
989
990</div>
991
992<!-- ======================================================================= -->
993<div class="doc_subsection">
994 <a name="mips-be">Known problems with the MIPS back-end</a>
995</div>
996
997<div class="doc_text">
998
999<ul>
1000<li>The O32 ABI is not fully supported.</li>
1001<li>64-bit MIPS targets are not supported yet.</li>
1002</ul>
1003
1004</div>
1005
1006<!-- ======================================================================= -->
1007<div class="doc_subsection">
1008 <a name="alpha-be">Known problems with the Alpha back-end</a>
1009</div>
1010
1011<div class="doc_text">
1012
1013<ul>
1014
1015<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1016appropriate nops inserted to ensure restartability.</li>
1017
1018</ul>
1019</div>
1020
1021<!-- ======================================================================= -->
1022<div class="doc_subsection">
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]1023 <a name="c-be">Known problems with the C back-end</a>
1024</div>
1025
1026<div class="doc_text">
1027
1028<ul>
1029<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1030 inline assembly code</a>.</li>
1031<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1032 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1033 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1034<li>The C backend does not support all exception handling constructs.</li>
1035<li>The C backend does not support arbitrary precision integers.</li>
1036</ul>
1037
1038</div>
1039
1040
1041<!-- ======================================================================= -->
1042<div class="doc_subsection">
1043 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
1044</div>
1045
1046<div class="doc_text">
1047
1048<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
1049Optimization</a> on most platforms "out-of-the-box". Please inquire on the
1050LLVMdev mailing list if you are interested.</p>
1051
1052<p>The only major language feature of GCC not supported by llvm-gcc is
1053 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1054 are only supported on some targets. For example, trampolines are only
1055 supported on some targets (these are used when you take the address of a
1056 nested function).</p>
1057
1058<p>If you run into GCC extensions which are not supported, please let us know.
1059</p>
1060
1061</div>
1062
1063<!-- ======================================================================= -->
1064<div class="doc_subsection">
1065 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
1066</div>
1067
1068<div class="doc_text">
1069
1070<p>The C++ front-end is considered to be fully
1071tested and works for a number of non-trivial programs, including LLVM
1072itself, Qt, Mozilla, etc.</p>
1073
1074<ul>
1075<li>Exception handling works well on the X86 and PowerPC targets. Currently
1076 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
1077</ul>
1078
1079</div>
1080
1081<!-- ======================================================================= -->
1082<div class="doc_subsection">
1083 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1084</div>
1085
1086<div class="doc_text">
1087<ul>
1088<li>Fortran support generally works, but there are still several unresolved bugs
1089 in Bugzilla. Please see the tools/gfortran component for details.</li>
1090</ul>
1091</div>
1092
1093<!-- ======================================================================= -->
1094<div class="doc_subsection">
1095 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1096</div>
1097
1098<div class="doc_text">
1099The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1100technology, and problems should be expected.
1101<ul>
1102<li>The Ada front-end currently only builds on X86-32. This is mainly due
1103to lack of trampoline support (pointers to nested functions) on other platforms.
1104However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1105which does support trampolines.</li>
1106<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1107This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1108exception handling, which is used internally by the compiler.
1109Workaround: configure with --disable-bootstrap.</li>
1110<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1111and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1112(c380004 also fails with gcc-4.2 mainline).
1113If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1114causes the compiler to go into an infinite loop, using up all system memory.</li>
1115<li>Some GCC specific Ada tests continue to crash the compiler.</li>
1116<li>The -E binder option (exception backtraces)
1117<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1118crashing if an exception is raised. Workaround: do not use -E.</li>
1119<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1120or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1121or use representation clauses that result in a field of a non-discrete type
1122starting or finishing in the middle of a byte.</li>
1123<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1124'main' as generated by the Ada binder to be invalid</a>.
1125Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1126<tt>envp</tt> rather than integers.</li>
1127<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1128ignored</a>.</li>
1129</ul>
1130</div>
1131
Erick Tryzelaar17167be2009-09-28 04:42:55 +0000[diff] [blame]1132<!-- ======================================================================= -->
1133<div class="doc_subsection">
1134 <a name="ocaml-bindingse">Known problems with the O'Caml bindings</a>
1135</div>
1136
1137<div class="doc_text">
1138
1139<p>The Llvm.Linkage module is broken, and has incorrect values. Only
1140Llvm.Linkage.External, Llvm.Linkage.Available_externally, and
1141Llvm.Linkage.Link_once will be correct. If you need any of the other linkage
1142modes, you'll have to write an external C library in order to expose the
1143functionality. This has been fixed in the trunk.</p>
1144</div>
1145
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]1146<!-- *********************************************************************** -->
1147<div class="doc_section">
1148 <a name="additionalinfo">Additional Information</a>
1149</div>
1150<!-- *********************************************************************** -->
1151
1152<div class="doc_text">
1153
1154<p>A wide variety of additional information is available on the <a
1155href="http://llvm.org">LLVM web page</a>, in particular in the <a
1156href="http://llvm.org/docs/">documentation</a> section. The web page also
1157contains versions of the API documentation which is up-to-date with the
1158Subversion version of the source code.
1159You can access versions of these documents specific to this release by going
1160into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1161
1162<p>If you have any questions or comments about LLVM, please feel free to contact
1163us via the <a href="http://llvm.org/docs/#maillist"> mailing
1164lists</a>.</p>
1165
1166</div>
1167
1168<!-- *********************************************************************** -->
1169
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