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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>
54
55<!-- Unfinished features in 2.5:
56 Machine LICM
57 Machine Sinking
58 target-specific intrinsics
59 gold lto plugin
60 pre-alloc splitter, strong phi elim
61 <tt>llc -enable-value-prop</tt>, propagation of value info
62 (sign/zero ext info) from one MBB to another
63 debug info for optimized code
64 interpreter + libffi
65 postalloc scheduler: anti dependence breaking, hazard recognizer?
66
67initial support for debug line numbers when optimization enabled, not useful in
68 2.5 but will be for 2.6.
69
70 -->
71
72 <!-- for announcement email:
73 -->
74
75<!-- *********************************************************************** -->
76<div class="doc_section">
77 <a name="subproj">Sub-project Status Update</a>
78</div>
79<!-- *********************************************************************** -->
80
81<div class="doc_text">
82<p>
83The LLVM 2.6 distribution currently consists of code from the core LLVM
84repository &mdash;which roughly includes the LLVM optimizers, code generators
85and supporting tools &mdash; and the llvm-gcc repository. In addition to this
86code, the LLVM Project includes other sub-projects that are in development. The
87two which are the most actively developed are the <a href="#clang">Clang
88Project</a> and the <a href="#vmkit">VMKit Project</a>.
89</p>
90
91</div>
92
93
94<!--=========================================================================-->
95<div class="doc_subsection">
96<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
97</div>
98
99<div class="doc_text">
100
101<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
102a set of new 'LLVM native' front-end technologies for the LLVM optimizer and
103code generator. While Clang is not included in the LLVM 2.6 release, it is
104continuing to make major strides forward in all areas. Its C and Objective-C
105parsing and code generation support is now very solid. For example, it is
106capable of successfully building many real-world applications for X86-32
107and X86-64,
108including the <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">FreeBSD
109kernel</a> and <a href="http://gcc.gnu.org/gcc-4.2/">gcc 4.2</a>. C++ is also
110making <a href="http://clang.llvm.org/cxx_status.html">incredible progress</a>,
111and work on templates has recently started. If you are
112interested in fast compiles and good diagnostics, we encourage you to try it out
113by <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
114and reporting any issues you hit to the <a
115href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
116list</a>.</p>
117
118<p>In the LLVM 2.6 time-frame, the Clang team has made many improvements:</p>
119
120<ul>
121<li>Something wonderful!</li>
122<li>Many many bugs are fixed and many features have been added.</li>
123</ul>
124</div>
125
126<!--=========================================================================-->
127<div class="doc_subsection">
128<a name="clangsa">Clang Static Analyzer</a>
129</div>
130
131<div class="doc_text">
132
133<p>Previously announced in the 2.4 LLVM release, the Clang project also
134includes an early stage static source code analysis tool for <a
135href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
136in C and Objective-C programs. The tool performs a growing set of checks to find
137bugs that occur on a specific path within a program.</p>
138
139<p>In the LLVM 2.6 time-frame there have been many significant improvements to
140XYZ.</p>
141
142<p>The set of checks performed by the static analyzer continues to expand, and
143future plans for the tool include full source-level inter-procedural analysis
144and deeper checks such as buffer overrun detection. There are many opportunities
145to extend and enhance the static analyzer, and anyone interested in working on
146this project is encouraged to get involved!</p>
147
148</div>
149
150<!--=========================================================================-->
151<div class="doc_subsection">
152<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
153</div>
154
155<div class="doc_text">
156<p>
157The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
158a JVM and a CLI Virtual Machines (Microsoft .NET is an
159implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
160
161<p>Following LLVM 2.6, VMKit has its XYZ release that you can find on its
162<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
163bug fixes, cleanup and new features. The major changes are:</p>
164
165<ul>
166
167<li>Something wonderful!</li>
168
169</ul>
170</div>
171
172<!-- *********************************************************************** -->
173<div class="doc_section">
174 <a name="externalproj">External Projects Using LLVM 2.6</a>
175</div>
176<!-- *********************************************************************** -->
177
178<!--=========================================================================-->
179<div class="doc_subsection">
180<a name="pure">Pure</a>
181</div>
182
183<div class="doc_text">
184<p>
185<a href="http://pure-lang.googlecode.com/">Pure</a>
186is an algebraic/functional programming language based on term rewriting.
187Programs are collections of equations which are used to evaluate expressions in
188a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
189lexical closures, a hygienic macro system (also based on term rewriting),
190built-in list and matrix support (including list and matrix comprehensions) and
191an easy-to-use C interface. The interpreter uses LLVM as a backend to
192 JIT-compile Pure programs to fast native code.</p>
193
194<p>In addition to the usual algebraic data structures, Pure also has
195MATLAB-style matrices in order to support numeric computations and signal
196processing in an efficient way. Pure is mainly aimed at mathematical
197applications right now, but it has been designed as a general purpose language.
198The dynamic interpreter environment and the C interface make it possible to use
199it as a kind of functional scripting language for many application areas.
200</p>
201</div>
202
203
204<!--=========================================================================-->
205<div class="doc_subsection">
206<a name="ldc">LLVM D Compiler</a>
207</div>
208
209<div class="doc_text">
210<p>
211<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
212the D Programming Language using the LLVM optimizer and code generator.
213The LDC project works great with the LLVM 2.6 release. General improvements in
214this
215cycle have included new inline asm constraint handling, better debug info
216support, general bugfixes, and better x86-64 support. This has allowed
217some major improvements in LDC, getting us much closer to being as
218fully featured as the original DMD compiler from DigitalMars.
219</p>
220</div>
221
222<!--=========================================================================-->
223<div class="doc_subsection">
224<a name="RoadsendPHP">Roadsend PHP</a>
225</div>
226
227<div class="doc_text">
228<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
229source implementation of the PHP programming
230language that uses LLVM for its optimizer, JIT, and static compiler. This is a
231reimplementation of an earlier project that is now based on LLVM.</p>
232</div>
233
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]234<!--=========================================================================-->
235<div class="doc_subsection">
236<a name="Unladen Swallow">Unladen Swallow</a>
237</div>
238
239<div class="doc_text">
240<p><a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
241branch of <a href="http://python.org/">Python</a> intended to be fully
242compatible and significantly faster. It uses LLVM's optimization passes and JIT
243compiler.</p>
244</div>
245
Jeffrey Yasskin5e98cb72009-06-24 21:26:42 +0000[diff] [blame]246<!--=========================================================================-->
247<div class="doc_subsection">
248<a name="Rubinius">Rubinius</a>
249</div>
250
251<div class="doc_text">
252<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is a new virtual
253machine for Ruby. It leverages LLVM to dynamically compile Ruby code down to
254machine code using LLVM's JIT.</p>
255</div>
256
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]257
258<!-- *********************************************************************** -->
259<div class="doc_section">
260 <a name="whatsnew">What's New in LLVM 2.6?</a>
261</div>
262<!-- *********************************************************************** -->
263
264<div class="doc_text">
265
266<p>This release includes a huge number of bug fixes, performance tweaks, and
267minor improvements. Some of the major improvements and new features are listed
268in this section.
269</p>
270</div>
271
272<!--=========================================================================-->
273<div class="doc_subsection">
274<a name="majorfeatures">Major New Features</a>
275</div>
276
277<div class="doc_text">
278
279<p>LLVM 2.6 includes several major new capabilities:</p>
280
281<ul>
282<li>Something wonderful!</li>
283</ul>
284
285</div>
286
287
288<!--=========================================================================-->
289<div class="doc_subsection">
290<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
291</div>
292
293<div class="doc_text">
294
295<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
296front-ends and driver with the LLVM optimizer and code generator. It currently
297includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
298
299<ul>
300<li>Something wonderful!</li>
301</ul>
302
303</div>
304
305
306<!--=========================================================================-->
307<div class="doc_subsection">
308<a name="coreimprovements">LLVM IR and Core Improvements</a>
309</div>
310
311<div class="doc_text">
312<p>LLVM IR has several new features that are used by our existing front-ends and
313can be useful if you are writing a front-end for LLVM:</p>
314
315<ul>
316<li>Something wonderful!</li>
317</ul>
318
319</div>
320
321<!--=========================================================================-->
322<div class="doc_subsection">
323<a name="optimizer">Optimizer Improvements</a>
324</div>
325
326<div class="doc_text">
327
328<p>In addition to a large array of bug fixes and minor performance tweaks, this
329release includes a few major enhancements and additions to the optimizers:</p>
330
331<ul>
332
333<li>Something wonderful!</li>
334
335</ul>
336
337</div>
338
339<!--=========================================================================-->
340<div class="doc_subsection">
341<a name="codegen">Target Independent Code Generator Improvements</a>
342</div>
343
344<div class="doc_text">
345
346<p>We have put a significant amount of work into the code generator
347infrastructure, which allows us to implement more aggressive algorithms and make
348it run faster:</p>
349
350<ul>
351
352<li>Something wonderful!</li>
353</ul>
354</div>
355
356<!--=========================================================================-->
357<div class="doc_subsection">
358<a name="x86">X86-32 and X86-64 Target Improvements</a>
359</div>
360
361<div class="doc_text">
362<p>New features of the X86 target include:
363</p>
364
365<ul>
366
367<li>Something wonderful!</li>
368</ul>
369
370</div>
371
372<!--=========================================================================-->
373<div class="doc_subsection">
374<a name="pic16">PIC16 Target Improvements</a>
375</div>
376
377<div class="doc_text">
378<p>New features of the PIC16 target include:
379</p>
380
381<ul>
382<li>Something wonderful!</li>
383</ul>
384
385<p>Things not yet supported:</p>
386
387<ul>
388<li>Floating point.</li>
389<li>Passing/returning aggregate types to and from functions.</li>
390<li>Variable arguments.</li>
391<li>Indirect function calls.</li>
392<li>Interrupts/programs.</li>
393<li>Debug info.</li>
394</ul>
395
396</div>
397
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame^]398<!--=========================================================================-->
399<div class="doc_subsection">
400<a name="ARM">ARM Target Improvements</a>
401</div>
402
403<div class="doc_text">
404<p>New features of the ARM target include:
405</p>
406
407<ul>
408
409<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
410that implement version 7 of the ARM architecture. The ARM backend now
411supports both the Thumb2 and Advanced SIMD (Neon) instruction sets.
412These features are still somewhat experimental and subject to change.
413The Neon intrinsics, in particular, may change in future releases of LLVM.
414</li>
415</ul>
416
417</div>
418
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]419
420<!--=========================================================================-->
421<div class="doc_subsection">
422<a name="llvmc">Improvements in LLVMC</a>
423</div>
424
425<div class="doc_text">
426<p>New features include:</p>
427
428<ul>
429<li>Something wonderful!</li>
430</ul>
431
432</div>
433
434
435<!--=========================================================================-->
436<div class="doc_subsection">
437<a name="changes">Major Changes and Removed Features</a>
438</div>
439
440<div class="doc_text">
441
442<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]443on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]444from the previous release.</p>
445
446<ul>
447
448<li>Something horrible!</li>
449
450</ul>
451
452
453<p>In addition, many APIs have changed in this release. Some of the major LLVM
454API changes are:</p>
455
456<ul>
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]457<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
458 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
459 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
460 for clients that will only ever use a single context, the new
461 <tt>getGlobalContext()</tt> API can be used to access a default global
462 context which can be passed in any and all cases where a context is
463 required.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]464<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohmanf667e7e2009-07-07 20:05:15 +0000[diff] [blame]465<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
466 overloaded for floating-point types. Floating-point addition, subtraction,
467 and multiplication are now represented with new operators <tt>FAdd</tt>,
468 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
469 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
470 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
471 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
472 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbar02e73132009-07-12 20:41:27 +0000[diff] [blame]473<li>The DynamicLibrary class can no longer be constructed, its functionality has
474 moved to static member functions.</li>
Dan Gohmane4d54d72009-07-15 19:59:19 +0000[diff] [blame]475<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
476 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
477 <tt>false</tt>, an error will be reported if a file with the given name
478 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
479 be silently truncated (which is the behavior before this flag was
480 added).</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]481<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
482longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
483used.</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]484
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]485<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
486and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
487or <tt>std::string</tt>, as described in
488the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]489clients 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:
490 <ul>
491 <li><tt>getNameStr()</tt> is still available, and matches the old
492 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
493 although more efficient alternatives are now possible.</li>
494
495 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
496 a <tt>std::ostream</tt>, consider migrating
497 to <tt>llvm::raw_ostream</tt>.</li>
498
499 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
500 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
501 Note that this string (as before), may not be the entire name if the
502 name containts embedded null characters.</li>
503
504 <li>If you were using operator plus on the result of <tt>getName()</tt> and
505 treating the result as an <tt>std::string</tt>, you can either
506 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
507 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbar03d76512009-07-25 23:55:21 +0000[diff] [blame]508
509 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramere15192b2009-08-05 15:42:44 +0000[diff] [blame]510 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]511 </ul>
512</li>
513
Daniel Dunbara5881e32009-07-26 02:12:58 +0000[diff] [blame]514<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbard6b06b12009-07-26 05:41:39 +0000[diff] [blame]515previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
516 <ul>
517 <li><tt>TargetMachineRegistry</tt> has been renamed
518 to <tt>TargetRegistry</tt>.</li>
519
520 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
521 function to find targets.</li>
522 </ul>
523</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]524
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]525<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]526FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
527This is not an API change, maybe there should be a tool changes section?</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]528<li>temporarely due to Context API change passes should call doInitialization()
529method of the pass they inherit from, otherwise Context is NULL.
530FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]531</ul>
532
533</div>
534
535
536
537<!-- *********************************************************************** -->
538<div class="doc_section">
539 <a name="portability">Portability and Supported Platforms</a>
540</div>
541<!-- *********************************************************************** -->
542
543<div class="doc_text">
544
545<p>LLVM is known to work on the following platforms:</p>
546
547<ul>
548<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]549Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]550<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
551and 64-bit modes.</li>
552<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
553<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
554 support is available for native builds with Visual C++).</li>
555<li>Sun UltraSPARC workstations running Solaris 10.</li>
556<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]557</ul>
558
559<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
560to the machine and operating system on which it is built. However, minor
561porting may be required to get LLVM to work on new platforms. We welcome your
562portability patches and reports of successful builds or error messages.</p>
563
564</div>
565
566<!-- *********************************************************************** -->
567<div class="doc_section">
568 <a name="knownproblems">Known Problems</a>
569</div>
570<!-- *********************************************************************** -->
571
572<div class="doc_text">
573
574<p>This section contains significant known problems with the LLVM system,
575listed by component. If you run into a problem, please check the <a
576href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
577there isn't already one.</p>
578
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]579<ul>
Chris Lattneraedb59a2009-07-21 23:17:26 +0000[diff] [blame]580<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]581using the stock GCC 3.x.x series 'out the box',
582See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
583However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
584for x86/x64 has been made available from the third party AuroraUX Project
585that has been meticulously tested for bootstrapping LLVM & Clang.</li>
586</ul>
587
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]588</div>
589
590<!-- ======================================================================= -->
591<div class="doc_subsection">
592 <a name="experimental">Experimental features included with this release</a>
593</div>
594
595<div class="doc_text">
596
597<p>The following components of this LLVM release are either untested, known to
598be broken or unreliable, or are in early development. These components should
599not be relied on, and bugs should not be filed against them, but they may be
600useful to some people. In particular, if you would like to work on one of these
601components, please contact us on the <a
602href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
603
604<ul>
Dan Gohmand2cb3d22009-07-24 00:30:09 +0000[diff] [blame]605<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]606<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
607 supported value for this option.</li>
608</ul>
609
610</div>
611
612<!-- ======================================================================= -->
613<div class="doc_subsection">
614 <a name="x86-be">Known problems with the X86 back-end</a>
615</div>
616
617<div class="doc_text">
618
619<ul>
620 <li>The X86 backend does not yet support
621 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
622 floating point stack</a>. It supports the 'f' and 't' constraints, but not
623 'u'.</li>
624 <li>The X86 backend generates inefficient floating point code when configured
625 to generate code for systems that don't have SSE2.</li>
626 <li>Win64 code generation wasn't widely tested. Everything should work, but we
627 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
628 runtime currently due
629 to <a href="http://llvm.org/PR2255">several</a>
630 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
631 the
632 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
633 <li>The X86-64 backend does not yet support the LLVM IR instruction
634 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
635 argument constructs on X86-64 by lowering them manually.</li>
636</ul>
637
638</div>
639
640<!-- ======================================================================= -->
641<div class="doc_subsection">
642 <a name="ppc-be">Known problems with the PowerPC back-end</a>
643</div>
644
645<div class="doc_text">
646
647<ul>
648<li>The Linux PPC32/ABI support needs testing for the interpreter and static
649compilation, and lacks support for debug information.</li>
650</ul>
651
652</div>
653
654<!-- ======================================================================= -->
655<div class="doc_subsection">
656 <a name="arm-be">Known problems with the ARM back-end</a>
657</div>
658
659<div class="doc_text">
660
661<ul>
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame^]662<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
663and not well tested. Some features may not work at all, and the code quality
664may be poor in some cases.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]665<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
666processors, thumb programs can crash or produce wrong
667results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
668<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
669</li>
670<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
671 execute
672programs compiled with LLVM. Please use more recent versions of QEMU.</li>
673</ul>
674
675</div>
676
677<!-- ======================================================================= -->
678<div class="doc_subsection">
679 <a name="sparc-be">Known problems with the SPARC back-end</a>
680</div>
681
682<div class="doc_text">
683
684<ul>
685<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
686 support the 64-bit SPARC ABI (-m64).</li>
687</ul>
688
689</div>
690
691<!-- ======================================================================= -->
692<div class="doc_subsection">
693 <a name="mips-be">Known problems with the MIPS back-end</a>
694</div>
695
696<div class="doc_text">
697
698<ul>
699<li>The O32 ABI is not fully supported.</li>
700<li>64-bit MIPS targets are not supported yet.</li>
701</ul>
702
703</div>
704
705<!-- ======================================================================= -->
706<div class="doc_subsection">
707 <a name="alpha-be">Known problems with the Alpha back-end</a>
708</div>
709
710<div class="doc_text">
711
712<ul>
713
714<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
715appropriate nops inserted to ensure restartability.</li>
716
717</ul>
718</div>
719
720<!-- ======================================================================= -->
721<div class="doc_subsection">
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]722 <a name="c-be">Known problems with the C back-end</a>
723</div>
724
725<div class="doc_text">
726
727<ul>
728<li><a href="http://llvm.org/PR802">The C backend has only basic support for
729 inline assembly code</a>.</li>
730<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
731 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
732 C++ code compiled with <tt>llc</tt> or native compilers.</li>
733<li>The C backend does not support all exception handling constructs.</li>
734<li>The C backend does not support arbitrary precision integers.</li>
735</ul>
736
737</div>
738
739
740<!-- ======================================================================= -->
741<div class="doc_subsection">
742 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
743</div>
744
745<div class="doc_text">
746
747<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
748Optimization</a> on most platforms "out-of-the-box". Please inquire on the
749LLVMdev mailing list if you are interested.</p>
750
751<p>The only major language feature of GCC not supported by llvm-gcc is
752 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
753 are only supported on some targets. For example, trampolines are only
754 supported on some targets (these are used when you take the address of a
755 nested function).</p>
756
757<p>If you run into GCC extensions which are not supported, please let us know.
758</p>
759
760</div>
761
762<!-- ======================================================================= -->
763<div class="doc_subsection">
764 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
765</div>
766
767<div class="doc_text">
768
769<p>The C++ front-end is considered to be fully
770tested and works for a number of non-trivial programs, including LLVM
771itself, Qt, Mozilla, etc.</p>
772
773<ul>
774<li>Exception handling works well on the X86 and PowerPC targets. Currently
775 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
776</ul>
777
778</div>
779
780<!-- ======================================================================= -->
781<div class="doc_subsection">
782 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
783</div>
784
785<div class="doc_text">
786<ul>
787<li>Fortran support generally works, but there are still several unresolved bugs
788 in Bugzilla. Please see the tools/gfortran component for details.</li>
789</ul>
790</div>
791
792<!-- ======================================================================= -->
793<div class="doc_subsection">
794 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
795</div>
796
797<div class="doc_text">
798The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
799technology, and problems should be expected.
800<ul>
801<li>The Ada front-end currently only builds on X86-32. This is mainly due
802to lack of trampoline support (pointers to nested functions) on other platforms.
803However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
804which does support trampolines.</li>
805<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
806This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
807exception handling, which is used internally by the compiler.
808Workaround: configure with --disable-bootstrap.</li>
809<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
810and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
811(c380004 also fails with gcc-4.2 mainline).
812If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
813causes the compiler to go into an infinite loop, using up all system memory.</li>
814<li>Some GCC specific Ada tests continue to crash the compiler.</li>
815<li>The -E binder option (exception backtraces)
816<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
817crashing if an exception is raised. Workaround: do not use -E.</li>
818<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
819or finish at a non-byte offset</a> in a record. Workaround: do not pack records
820or use representation clauses that result in a field of a non-discrete type
821starting or finishing in the middle of a byte.</li>
822<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
823'main' as generated by the Ada binder to be invalid</a>.
824Workaround: hand edit the file to use pointers for <tt>argv</tt> and
825<tt>envp</tt> rather than integers.</li>
826<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
827ignored</a>.</li>
828</ul>
829</div>
830
831<!-- *********************************************************************** -->
832<div class="doc_section">
833 <a name="additionalinfo">Additional Information</a>
834</div>
835<!-- *********************************************************************** -->
836
837<div class="doc_text">
838
839<p>A wide variety of additional information is available on the <a
840href="http://llvm.org">LLVM web page</a>, in particular in the <a
841href="http://llvm.org/docs/">documentation</a> section. The web page also
842contains versions of the API documentation which is up-to-date with the
843Subversion version of the source code.
844You can access versions of these documents specific to this release by going
845into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
846
847<p>If you have any questions or comments about LLVM, please feel free to contact
848us via the <a href="http://llvm.org/docs/#maillist"> mailing
849lists</a>.</p>
850
851</div>
852
853<!-- *********************************************************************** -->
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