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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>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]167<b>UPDATE!</b>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]168The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
169a JVM and a CLI Virtual Machines (Microsoft .NET is an
170implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
171
172<p>Following LLVM 2.6, VMKit has its XYZ release that you can find on its
173<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
174bug fixes, cleanup and new features. The major changes are:</p>
175
176<ul>
177
178<li>Something wonderful!</li>
179
180</ul>
181</div>
182
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]183
184<!--=========================================================================-->
185<div class="doc_subsection">
186<a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
187</div>
188
189<div class="doc_text">
190<p>
191The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
192is a simple library that provides an implementation of the low-level
193target-specific hooks required by code generation and other runtime components.
194For example, when compiling for a 32-bit target, converting a double to a 64-bit
195unsigned integer is compiling into a runtime call to the "__fixunsdfdi"
196function. The compiler-rt library provides optimized implementations of this and
197other low-level routines.</p>
198
199<p>
200All of the code in the compiler-rt project is available under the standard LLVM
201License, a "BSD-style" license.</p>
202
203</div>
204
205<!--=========================================================================-->
206<div class="doc_subsection">
207<a name="klee">klee: Symbolic Execution and Automatic Test Case Generator</a>
208</div>
209
210<div class="doc_text">
211<p>
212The new LLVM <a href="http://klee.llvm.org/">klee project</a> is a symbolic
213execution framework for programs in LLVM bitcode form. Klee tries to
214symbolically evaluate "all" paths through the application and records state
215transitions that lead to fault states. This allows it to construct testcases
216that lead to faults and can even be used to verify algorithms. For more
217details, please see the <a
218href="http://llvm.org/pubs/2008-12-OSDI-KLEE.html">OSDI 2008 paper</a> about
219Klee.</p>
220
221</div>
222
223<!--=========================================================================-->
224<div class="doc_subsection">
225<a name="dragonegg">Dragon Egg: An LLVM backend plugin for GCC</a>
226</div>
227
228<div class="doc_text">
229<p>
230<b>Duncan needs to write me</b>.
231</p>
232
233</div>
234
235
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]236<!--=========================================================================-->
237<div class="doc_subsection">
238<a name="mc">llvm-mc: Machine Code Toolkit</a>
239</div>
240
241<div class="doc_text">
242<p>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]243The LLVM Machine Code (MC) Toolkit project is a (very early) effort to build
244better tools for dealing with machine code, object file formats, etc. The idea
245is to be able to generate most of the target specific details of assemblers and
246disassemblers from existing LLVM target .td files (with suitable enhancements),
247and to build infrastructure for reading and writing common object file formats.
248One of the first deliverables is to build a full assembler and integrate it into
249the compiler, which is predicted to substantially reduce compile time in some
250scenarios.
251</p>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]252
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]253<p>In the LLVM 2.6 timeframe, the MC framework has grown to the point where it
254can reliably parse and pretty print (with some encoding information) a
255darwin/x86 .s file successfully, and has the very early phases of a Mach-O
256assembler in progress. Beyond the MC framework itself, major refactoring of the
257LLVM code generator has started. The idea is to make the code generator reason
258about the code it is producing in a much more semantic way, rather than a
259textual way. For example, the code generator now uses MCSection objects to
260represent section assignments, instead of text strings that print to .section
261directives.</p>
262
263<p>MC is an early and ongoing project that will hopefully continue to lead to
264many improvements in the code generator and build infrastructure useful for many
265other situations.
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]266</p>
267
268</div>
269
270
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]271<!-- *********************************************************************** -->
272<div class="doc_section">
273 <a name="externalproj">External Projects Using LLVM 2.6</a>
274</div>
275<!-- *********************************************************************** -->
276
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]277<!--=========================================================================-->
278<div class="doc_subsection">
279<a name="Rubinius">Rubinius</a>
280</div>
281
282<div class="doc_text">
283<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
284for running Ruby code which strives to write as much of the core class
285implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
286uses LLVM to optimize and compile ruby code down to machine code. Techniques
287such as type feedback, method inlining, and uncommon traps are all used to
288remove dynamism from ruby execution and increase performance.</p>
Chris Lattnerd4a537b2009-10-08 16:01:33 +0000[diff] [blame]289
290<p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
291a counter based JIT, type feedback, and speculative method inlining.
292</p>
293
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]294</div>
Chris Lattnerc32a5322009-09-30 06:27:22 +0000[diff] [blame]295
296<!--=========================================================================-->
297<div class="doc_subsection">
298<a name="macruby">MacRuby</a>
299</div>
300
301<div class="doc_text">
302
303<p>
304<a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
305core Mac OS X technologies, such as the Objective-C common runtime and garbage
306collector, and the CoreFoundation framework. It is principally developed by
307Apple and aims at enabling the creation of full-fledged Mac OS X applications.
308</p>
309
310<p>
311MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
312expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
313handling.</p>
314
315</div>
316
317
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]318<!--=========================================================================-->
319<div class="doc_subsection">
320<a name="pure">Pure</a>
321</div>
322
323<div class="doc_text">
324<p>
325<a href="http://pure-lang.googlecode.com/">Pure</a>
326is an algebraic/functional programming language based on term rewriting.
327Programs are collections of equations which are used to evaluate expressions in
328a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
329lexical closures, a hygienic macro system (also based on term rewriting),
330built-in list and matrix support (including list and matrix comprehensions) and
331an easy-to-use C interface. The interpreter uses LLVM as a backend to
332 JIT-compile Pure programs to fast native code.</p>
333
Chris Lattnerd4a537b2009-10-08 16:01:33 +0000[diff] [blame]334<p>Pure versions 0.31 and later have been tested and are known to work with
335LLVM 2.6 (and continue to work with older LLVM releases >= 2.3 as well).
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]336</p>
337</div>
338
339
340<!--=========================================================================-->
341<div class="doc_subsection">
342<a name="ldc">LLVM D Compiler</a>
343</div>
344
345<div class="doc_text">
346<p>
347<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
348the D Programming Language using the LLVM optimizer and code generator.
349The LDC project works great with the LLVM 2.6 release. General improvements in
350this
351cycle have included new inline asm constraint handling, better debug info
352support, general bugfixes, and better x86-64 support. This has allowed
353some major improvements in LDC, getting us much closer to being as
354fully featured as the original DMD compiler from DigitalMars.
355</p>
356</div>
357
358<!--=========================================================================-->
359<div class="doc_subsection">
360<a name="RoadsendPHP">Roadsend PHP</a>
361</div>
362
363<div class="doc_text">
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]364<p>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]365<a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]366source implementation of the PHP programming
367language that uses LLVM for its optimizer, JIT, and static compiler. This is a
368reimplementation of an earlier project that is now based on LLVM.</p>
369</div>
370
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]371<!--=========================================================================-->
372<div class="doc_subsection">
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]373<a name="UnladenSwallow">Unladen Swallow</a>
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]374</div>
375
376<div class="doc_text">
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]377<p>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]378<a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]379branch of <a href="http://python.org/">Python</a> intended to be fully
380compatible and significantly faster. It uses LLVM's optimization passes and JIT
381compiler.</p>
382</div>
383
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]384<!--=========================================================================-->
385<div class="doc_subsection">
386<a name="llvm-lua">llvm-lua</a>
387</div>
388
389<div class="doc_text">
390<p>
391<a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
392&amp; static compiling support to the Lua VM. Lua bytecode is analyzed to
393remove type checks, then LLVM is used to compile those bytecodes down to machine
394code.</p>
395</div>
396
Jeffrey Yasskin5e98cb72009-06-24 21:26:42 +0000[diff] [blame]397
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]398
399<!-- *********************************************************************** -->
400<div class="doc_section">
401 <a name="whatsnew">What's New in LLVM 2.6?</a>
402</div>
403<!-- *********************************************************************** -->
404
405<div class="doc_text">
406
407<p>This release includes a huge number of bug fixes, performance tweaks, and
408minor improvements. Some of the major improvements and new features are listed
409in this section.
410</p>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]411
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]412</div>
413
414<!--=========================================================================-->
415<div class="doc_subsection">
416<a name="majorfeatures">Major New Features</a>
417</div>
418
419<div class="doc_text">
420
421<p>LLVM 2.6 includes several major new capabilities:</p>
422
423<ul>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]424<li>New <a href="#compiler-rt">compiler-rt</a>, <A href="#klee">klee</a>,
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]425 and <a href="#mc">machine code toolkit</a> sub-projects.</li>
426<li>Debug information now includes line numbers when optimizations are enabled.
427 This allows statistical sampling tools like oprofile and Shark to map
428 samples back to source lines.</li>
429<li>LLVM now includes new experimental backends to support the MSP430, SystemZ,
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]430 and BlackFin architectures.</li>
431<li>LLVM supports a new <a href="GoldPlugin.html">Gold Linker Plugin</a> which
432 enables support for <a href="LinkTimeOptimization.html">transparent
433 link-time optimization</a> on ELF targets when used with the Gold binutils
434 linker.</li>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]435<li>LLVM now supports doing optimization and code generation on multiple threads
436 by allowing multiple "LLVMContext" objects to exist. Please see the <a
437 href="ProgrammersManual.html#threading">threading entry in the Programmer's
438 Manual</a> for more information.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]439</ul>
440
441</div>
442
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]443<!--=========================================================================-->
444<div class="doc_subsection">
445<a name="coreimprovements">LLVM IR and Core Improvements</a>
446</div>
447
448<div class="doc_text">
449<p>LLVM IR has several new features that are used by our existing front-ends and
450can be useful if you are writing a front-end for LLVM:</p>
451
452<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]453<li>Getelementpr instruction now allows any integer type for array/pointer indexes.</li>
454<li>Inbounds for GEP</li>
455<li>NSW/NUW/exact div</li>
456<li>LSR promotes int induction variables to 64-bit on 64-bit targets, major perf boost for numerical code.</li>
457<li>LSR now analyzes pointer expressions (e.g. getelementptrs), not just integers.</li>
458<li>new linkage types linkonce_odr, weak_odr, linker_private, and available_externally.</li>
459<li>New fadd, fsub, fmul instructions and classes. </li>
460<li>Target intrinsics can now return multiple results.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]461</ul>
462
463</div>
464
465<!--=========================================================================-->
466<div class="doc_subsection">
467<a name="optimizer">Optimizer Improvements</a>
468</div>
469
470<div class="doc_text">
471
472<p>In addition to a large array of bug fixes and minor performance tweaks, this
473release includes a few major enhancements and additions to the optimizers:</p>
474
475<ul>
476
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]477<li>SRoA improvements for vector unions, memset, arbitrary weird bitfield accesses etc. It now produces "strange" sized integers.</li>
478<li>Inliner reuse stack space when inlining arrays?</li>
479<li>Enabled GVN Load PRE.</li>
480<li>New Static Single Information (SSI) construction pass (not used by anything yet, experimental).</li>
481</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]482
483</ul>
484
485</div>
486
487<!--=========================================================================-->
488<div class="doc_subsection">
489<a name="codegen">Target Independent Code Generator Improvements</a>
490</div>
491
492<div class="doc_text">
493
494<p>We have put a significant amount of work into the code generator
495infrastructure, which allows us to implement more aggressive algorithms and make
496it run faster:</p>
497
498<ul>
499
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]500<li> -asm-verbose now prints location info (with -g) and loop nest info.</li>
501<li>Tblgen now supports multiclass inheritance and a number of new string and
502 list operations like !(subst), !(foreach), !car, !cdr, !null, !if, !cast.
503 These make the .td files more expressive and allow more aggressive factoring
504 of duplication across instruction patterns.</li>
505<li>New MachineVerifier pass.</li>
506<li>Machine LICM, hoists things like constant pool loads, loads from readonly stubs, vector constant synthesization code, etc.</li>
507<li>Machine Sinking</li>
508<li>target-specific intrinsics (r63765)</li>
509<li>Regalloc improvements for commuting, various spiller peephole optimizations, cross-class coalescing.</li>
510<li><tt>llc -enable-value-prop</tt>, propagation of value info (sign/zero ext info) from one MBB to another</li>
511<li>Regalloc hints for allocation stuff: Evan r73381/r73671. Finished/enabled?</li>
512<li>Stack slot coloring for register spills (denser stack frames)</li>
513<li>SelectionDAGS: New BuildVectorSDNode (r65296), and ISD::VECTOR_SHUFFLE (r69952 / PR2957)</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]514<li>Experimental support for shrink wrapping support in PEI.</li>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]515<li>Experimental support for writing ELF .o files directly from the compiler,
516 it works well for many simple C testcases, but doesn't support exception
517 handling, debug info, inline assembly, etc.</li>
518<li>Targets can now specify register allocation hints through
519 MachineRegisterInfo:: setRegAllocationHint. A regalloc hint consists 1) hint
520 type, 2) physical register number. A hint type of zero specifies a register
521 allocation preference. Other hint type values are target specific which are
522 resolved by TargetRegisterInfo::ResolveRegAllocHint. An example of which is
523 the ARM target can uses register hint to request that the register allocator
524 provide an even / odd register pair to two virtual registers. It is
525 important to note the register allocation hints are just hints. There is no
526 guarantee the register allocators will be able to satisfy the hints.</li>
527
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]528</ul>
529</div>
530
531<!--=========================================================================-->
532<div class="doc_subsection">
533<a name="x86">X86-32 and X86-64 Target Improvements</a>
534</div>
535
536<div class="doc_text">
537<p>New features of the X86 target include:
538</p>
539
540<ul>
541
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]542<li>Preliminary support for addrspace 256 -> GS, 257 -> FS, known problems: CodeGenerator.html#x86_memory</li>
543<li>Support for softfloat modes, typically used by OS kernels.</li>
544
545<li>X86-64: better modeling of implicit zero extensions, eliminates a lot of redundant zexts</li>
546<li>X86-64 TLS support for local exec and initial exec.</li>
547<li>Better modeling of H registerts as subregs.</li>
548<li>Vector icmp/fcmp now work with SSE codegen.</li>
549<li>SSE 4.2 support.</li>
550<li>all global variable reference logic is now in ClassifyGlobalReference.</li>
551</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]552</ul>
553
554</div>
555
556<!--=========================================================================-->
557<div class="doc_subsection">
558<a name="pic16">PIC16 Target Improvements</a>
559</div>
560
561<div class="doc_text">
562<p>New features of the PIC16 target include:
563</p>
564
565<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]566<li>Support for floating-point, indirect function calls, and
567 passing/returning aggregate types to functions.
568<li>The code generator is able to generate debug info into output COFF files.
569<li>Support for placing an object into a specific section or at a specific
570 address in memory.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]571</ul>
572
573<p>Things not yet supported:</p>
574
575<ul>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]576<li>Variable arguments.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]577<li>Interrupts/programs.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]578</ul>
579
580</div>
581
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]582<!--=========================================================================-->
583<div class="doc_subsection">
584<a name="ARM">ARM Target Improvements</a>
585</div>
586
587<div class="doc_text">
588<p>New features of the ARM target include:
589</p>
590
591<ul>
592
593<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel64e39612009-08-20 15:01:16 +0000[diff] [blame]594that implement version v7-A of the ARM architecture. The ARM backend now
595supports both the Thumb2 and Advanced SIMD (Neon) instruction sets. The
596AAPCS-VFP "hard float" calling conventions are also supported with the
597<tt>-float-abi=hard</tt> flag. These features are still somewhat experimental
598and subject to change. The Neon intrinsics, in particular, may change in future
599releases of LLVM.
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]600</li>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]601
602 ARM AAPCS-VFP hard float ABI is supported.
603 ARM calling convention code is now tblgen generated instead of manual.
604 ARM: NEON support. neonfp for doing single precision fp with neon instead of VFP.
605
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]606</ul>
607
608</div>
609
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]610<!--=========================================================================-->
611<div class="doc_subsection">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]612<a name="OtherTarget">Other Target Specific Improvements</a>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]613</div>
614
615<div class="doc_text">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]616<p>New features of other targets include:
617</p>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]618
619<ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]620<li>Add support for the PowerPC 64-bit SVR4 ABI.</li>
621<li>Mips now supports O32 Calling Convention.</li>
622</ul>
623
624</div>
625
626<!--=========================================================================-->
627<div class="doc_subsection">
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]628<a name="executionengine">Interpreter and JIT Improvements</a>
629</div>
630
631<div class="doc_text">
632
633<ul>
634<li>The JIT now supports generating more than 16M of code.</li>
635<li>When configured with --with-oprofile, the JIT can now inform oprofile about
636 JIT'd code, allowing oprofile to get line number and function name
637 information for JIT'd functions.</li>
638<li>When "libffi" is available, the LLVM interpreter now uses it, which supports
639 calling almost arbitrary external (natively compiled) functions.</li>
640<li>Clients of the JIT can now register a 'JITEventListener' object to receive
641 callbacks when the JIT emits or frees machine code. The OProfile support
642 uses this mechanism.</li>
643</ul>
644
645</div>
646
647
648<!--=========================================================================-->
649<div class="doc_subsection">
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]650<a name="newapis">New Useful APIs</a>
651</div>
652
653<div class="doc_text">
654
655<ul>
656<li>New EngineBuilder class for creating JITs: r76276</li>
657 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.
658 StringRef class, Twine class.
659 New WeakVH and AssertingVH and CallbackVH classes.
660 New llvm/ADT/Triple class.
661 llvm_report_error() error handling API (llvm/Support/ErrorHandling.h)
662 New llvm/System/Atomic.h, llvm/System/RWMutex.h for portable atomic ops, rw locks.
663 New SourceMgr, SMLoc classes for simple parsers with caret diagnostics and #include support, (used by
664 tablegen, llvm-mc, the .ll parser, FileCheck, etc)
665
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]666</ul>
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]667
668
669</div>
670
671<!--=========================================================================-->
672<div class="doc_subsection">
673<a name="otherimprovements">Other Improvements and New Features</a>
674</div>
675
676<div class="doc_text">
677<p>Other miscellaneous features include:</p>
678
679<ul>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]680<li>LLVM now includes a new internal '<a
681 href="http://llvm.org/cmds/FileCheck.html">FileCheck</a>' tool which allows
682 writing much more accurate regression tests that run faster. Please see the
683 <a href="TestingGuide.html#FileCheck">FileCheck section of the Testing
684 Guide</a> for more information.</li>
Chris Lattner6ee62f82009-10-09 05:55:04 +0000[diff] [blame]685<li>LLVM profile information support has been significantly improved to produce
686correct use counts, and has support for edge profiling with reduced runtime
687overhead. Combined, the generated profile information is both more correct and
688imposes about half as much overhead (2.6. from 12% to 6% overhead on SPEC
689CPU2000).</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]690<li>Many extensions to the C APIs.</li>
Chris Lattner45178502009-10-09 06:24:25 +0000[diff] [blame]691<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005
692programming language.</li>
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]693
694<li>LLVMC:
695
696* Dynamic plugins now work on Windows.
697* New option property: init. Makes possible to provide default values for
698 options defined in plugins (interface to cl::init).
699* New example: Skeleton, shows how to create a standalone LLVMC-based driver.
700* New example: mcc16, a driver for the PIC16 toolchain.</li>
701
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]702</ul>
703
704</div>
705
706
707<!--=========================================================================-->
708<div class="doc_subsection">
709<a name="changes">Major Changes and Removed Features</a>
710</div>
711
712<div class="doc_text">
713
714<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]715on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]716from the previous release.</p>
717
718<ul>
719
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]720<li>The Itanium (IA64) backend has been removed. It was not supported and
721 bitrotted.</li>
722<li>The BigBlock register allocator has been removed, it also bitrotted.</li>
723<li>The C Backend (-march=c) is no longer considered part of the LLVM release
724criteria. We still want it to work, but no one is maintaining it and it lacks
725support for arbitrary precision integers and other important IR features.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]726</ul>
727
Chris Lattner80ed2552009-10-08 07:01:46 +0000[diff] [blame]728 LLVM build now builds all libraries as .a files instead of some
729 libraries as relinked .o files. This requires some APIs like
730 InitializeAllTargets.h. TargetRegistry!
731
732
733
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]734
735<p>In addition, many APIs have changed in this release. Some of the major LLVM
736API changes are:</p>
737
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]738
739 API Cleanup:
740 no use of hash_set/hash_map, no more llvm::OStream
741 Use raw_ostream for everything, killed off llvm/Streams.h and DOUT
742
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]743<ul>
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]744<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
745 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
746 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
747 for clients that will only ever use a single context, the new
748 <tt>getGlobalContext()</tt> API can be used to access a default global
749 context which can be passed in any and all cases where a context is
750 required.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]751<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohmanf667e7e2009-07-07 20:05:15 +0000[diff] [blame]752<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
753 overloaded for floating-point types. Floating-point addition, subtraction,
754 and multiplication are now represented with new operators <tt>FAdd</tt>,
755 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
756 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
757 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
758 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
759 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbar02e73132009-07-12 20:41:27 +0000[diff] [blame]760<li>The DynamicLibrary class can no longer be constructed, its functionality has
761 moved to static member functions.</li>
Dan Gohmane4d54d72009-07-15 19:59:19 +0000[diff] [blame]762<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
763 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
764 <tt>false</tt>, an error will be reported if a file with the given name
765 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
766 be silently truncated (which is the behavior before this flag was
767 added).</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]768<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
769longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
770used.</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]771
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]772<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
773and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
774or <tt>std::string</tt>, as described in
775the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]776clients 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:
777 <ul>
778 <li><tt>getNameStr()</tt> is still available, and matches the old
779 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
780 although more efficient alternatives are now possible.</li>
781
782 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
783 a <tt>std::ostream</tt>, consider migrating
784 to <tt>llvm::raw_ostream</tt>.</li>
785
786 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
787 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
788 Note that this string (as before), may not be the entire name if the
789 name containts embedded null characters.</li>
790
791 <li>If you were using operator plus on the result of <tt>getName()</tt> and
792 treating the result as an <tt>std::string</tt>, you can either
793 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
794 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbar03d76512009-07-25 23:55:21 +0000[diff] [blame]795
796 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramere15192b2009-08-05 15:42:44 +0000[diff] [blame]797 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]798 </ul>
799</li>
800
Daniel Dunbara5881e32009-07-26 02:12:58 +0000[diff] [blame]801<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbard6b06b12009-07-26 05:41:39 +0000[diff] [blame]802previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
803 <ul>
804 <li><tt>TargetMachineRegistry</tt> has been renamed
805 to <tt>TargetRegistry</tt>.</li>
806
807 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
808 function to find targets.</li>
809 </ul>
810</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]811
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]812<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]813FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
814This is not an API change, maybe there should be a tool changes section?</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]815<li>temporarely due to Context API change passes should call doInitialization()
816method of the pass they inherit from, otherwise Context is NULL.
817FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]818</ul>
819
820</div>
821
822
823
824<!-- *********************************************************************** -->
825<div class="doc_section">
826 <a name="portability">Portability and Supported Platforms</a>
827</div>
828<!-- *********************************************************************** -->
829
830<div class="doc_text">
831
832<p>LLVM is known to work on the following platforms:</p>
833
834<ul>
835<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]836Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]837<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
838and 64-bit modes.</li>
839<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
840<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
841 support is available for native builds with Visual C++).</li>
842<li>Sun UltraSPARC workstations running Solaris 10.</li>
843<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]844</ul>
845
846<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
847to the machine and operating system on which it is built. However, minor
848porting may be required to get LLVM to work on new platforms. We welcome your
849portability patches and reports of successful builds or error messages.</p>
850
851</div>
852
853<!-- *********************************************************************** -->
854<div class="doc_section">
855 <a name="knownproblems">Known Problems</a>
856</div>
857<!-- *********************************************************************** -->
858
859<div class="doc_text">
860
861<p>This section contains significant known problems with the LLVM system,
862listed by component. If you run into a problem, please check the <a
863href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
864there isn't already one.</p>
865
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]866<ul>
Chris Lattneraedb59a2009-07-21 23:17:26 +0000[diff] [blame]867<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]868using the stock GCC 3.x.x series 'out the box',
869See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
870However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
871for x86/x64 has been made available from the third party AuroraUX Project
Chris Lattner7b0a6812009-10-08 06:27:53 +0000[diff] [blame]872that has been meticulously tested for bootstrapping LLVM &amp; Clang.</li>
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]873</ul>
874
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]875</div>
876
877<!-- ======================================================================= -->
878<div class="doc_subsection">
879 <a name="experimental">Experimental features included with this release</a>
880</div>
881
882<div class="doc_text">
883
884<p>The following components of this LLVM release are either untested, known to
885be broken or unreliable, or are in early development. These components should
886not be relied on, and bugs should not be filed against them, but they may be
887useful to some people. In particular, if you would like to work on one of these
888components, please contact us on the <a
889href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
890
891<ul>
Dan Gohmand2cb3d22009-07-24 00:30:09 +0000[diff] [blame]892<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]893<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
894 supported value for this option.</li>
895</ul>
896
897</div>
898
899<!-- ======================================================================= -->
900<div class="doc_subsection">
901 <a name="x86-be">Known problems with the X86 back-end</a>
902</div>
903
904<div class="doc_text">
905
906<ul>
907 <li>The X86 backend does not yet support
908 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
909 floating point stack</a>. It supports the 'f' and 't' constraints, but not
910 'u'.</li>
911 <li>The X86 backend generates inefficient floating point code when configured
912 to generate code for systems that don't have SSE2.</li>
913 <li>Win64 code generation wasn't widely tested. Everything should work, but we
914 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
915 runtime currently due
916 to <a href="http://llvm.org/PR2255">several</a>
917 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
918 the
919 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
920 <li>The X86-64 backend does not yet support the LLVM IR instruction
921 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
922 argument constructs on X86-64 by lowering them manually.</li>
923</ul>
924
925</div>
926
927<!-- ======================================================================= -->
928<div class="doc_subsection">
929 <a name="ppc-be">Known problems with the PowerPC back-end</a>
930</div>
931
932<div class="doc_text">
933
934<ul>
935<li>The Linux PPC32/ABI support needs testing for the interpreter and static
936compilation, and lacks support for debug information.</li>
937</ul>
938
939</div>
940
941<!-- ======================================================================= -->
942<div class="doc_subsection">
943 <a name="arm-be">Known problems with the ARM back-end</a>
944</div>
945
946<div class="doc_text">
947
948<ul>
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]949<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
950and not well tested. Some features may not work at all, and the code quality
951may be poor in some cases.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]952<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
953processors, thumb programs can crash or produce wrong
954results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
955<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
956</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]957</ul>
958
959</div>
960
961<!-- ======================================================================= -->
962<div class="doc_subsection">
963 <a name="sparc-be">Known problems with the SPARC back-end</a>
964</div>
965
966<div class="doc_text">
967
968<ul>
969<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
970 support the 64-bit SPARC ABI (-m64).</li>
971</ul>
972
973</div>
974
975<!-- ======================================================================= -->
976<div class="doc_subsection">
977 <a name="mips-be">Known problems with the MIPS back-end</a>
978</div>
979
980<div class="doc_text">
981
982<ul>
983<li>The O32 ABI is not fully supported.</li>
984<li>64-bit MIPS targets are not supported yet.</li>
985</ul>
986
987</div>
988
989<!-- ======================================================================= -->
990<div class="doc_subsection">
991 <a name="alpha-be">Known problems with the Alpha back-end</a>
992</div>
993
994<div class="doc_text">
995
996<ul>
997
998<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
999appropriate nops inserted to ensure restartability.</li>
1000
1001</ul>
1002</div>
1003
1004<!-- ======================================================================= -->
1005<div class="doc_subsection">
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]1006 <a name="c-be">Known problems with the C back-end</a>
1007</div>
1008
1009<div class="doc_text">
1010
1011<ul>
1012<li><a href="http://llvm.org/PR802">The C backend has only basic support for
1013 inline assembly code</a>.</li>
1014<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1015 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1016 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1017<li>The C backend does not support all exception handling constructs.</li>
1018<li>The C backend does not support arbitrary precision integers.</li>
1019</ul>
1020
1021</div>
1022
1023
1024<!-- ======================================================================= -->
1025<div class="doc_subsection">
1026 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
1027</div>
1028
1029<div class="doc_text">
1030
1031<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
1032Optimization</a> on most platforms "out-of-the-box". Please inquire on the
1033LLVMdev mailing list if you are interested.</p>
1034
1035<p>The only major language feature of GCC not supported by llvm-gcc is
1036 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1037 are only supported on some targets. For example, trampolines are only
1038 supported on some targets (these are used when you take the address of a
1039 nested function).</p>
1040
1041<p>If you run into GCC extensions which are not supported, please let us know.
1042</p>
1043
1044</div>
1045
1046<!-- ======================================================================= -->
1047<div class="doc_subsection">
1048 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
1049</div>
1050
1051<div class="doc_text">
1052
1053<p>The C++ front-end is considered to be fully
1054tested and works for a number of non-trivial programs, including LLVM
1055itself, Qt, Mozilla, etc.</p>
1056
1057<ul>
1058<li>Exception handling works well on the X86 and PowerPC targets. Currently
1059 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
1060</ul>
1061
1062</div>
1063
1064<!-- ======================================================================= -->
1065<div class="doc_subsection">
1066 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1067</div>
1068
1069<div class="doc_text">
1070<ul>
1071<li>Fortran support generally works, but there are still several unresolved bugs
1072 in Bugzilla. Please see the tools/gfortran component for details.</li>
1073</ul>
1074</div>
1075
1076<!-- ======================================================================= -->
1077<div class="doc_subsection">
1078 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1079</div>
1080
1081<div class="doc_text">
1082The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1083technology, and problems should be expected.
1084<ul>
1085<li>The Ada front-end currently only builds on X86-32. This is mainly due
1086to lack of trampoline support (pointers to nested functions) on other platforms.
1087However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1088which does support trampolines.</li>
1089<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1090This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1091exception handling, which is used internally by the compiler.
1092Workaround: configure with --disable-bootstrap.</li>
1093<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1094and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1095(c380004 also fails with gcc-4.2 mainline).
1096If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1097causes the compiler to go into an infinite loop, using up all system memory.</li>
1098<li>Some GCC specific Ada tests continue to crash the compiler.</li>
1099<li>The -E binder option (exception backtraces)
1100<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1101crashing if an exception is raised. Workaround: do not use -E.</li>
1102<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1103or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1104or use representation clauses that result in a field of a non-discrete type
1105starting or finishing in the middle of a byte.</li>
1106<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1107'main' as generated by the Ada binder to be invalid</a>.
1108Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1109<tt>envp</tt> rather than integers.</li>
1110<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1111ignored</a>.</li>
1112</ul>
1113</div>
1114
Erick Tryzelaar17167be2009-09-28 04:42:55 +0000[diff] [blame]1115<!-- ======================================================================= -->
1116<div class="doc_subsection">
1117 <a name="ocaml-bindingse">Known problems with the O'Caml bindings</a>
1118</div>
1119
1120<div class="doc_text">
1121
1122<p>The Llvm.Linkage module is broken, and has incorrect values. Only
1123Llvm.Linkage.External, Llvm.Linkage.Available_externally, and
1124Llvm.Linkage.Link_once will be correct. If you need any of the other linkage
1125modes, you'll have to write an external C library in order to expose the
1126functionality. This has been fixed in the trunk.</p>
1127</div>
1128
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]1129<!-- *********************************************************************** -->
1130<div class="doc_section">
1131 <a name="additionalinfo">Additional Information</a>
1132</div>
1133<!-- *********************************************************************** -->
1134
1135<div class="doc_text">
1136
1137<p>A wide variety of additional information is available on the <a
1138href="http://llvm.org">LLVM web page</a>, in particular in the <a
1139href="http://llvm.org/docs/">documentation</a> section. The web page also
1140contains versions of the API documentation which is up-to-date with the
1141Subversion version of the source code.
1142You can access versions of these documents specific to this release by going
1143into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1144
1145<p>If you have any questions or comments about LLVM, please feel free to contact
1146us via the <a href="http://llvm.org/docs/#maillist"> mailing
1147lists</a>.</p>
1148
1149</div>
1150
1151<!-- *********************************************************************** -->
1152
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