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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>
Edward O'Callaghan50310f92009-08-22 02:17:22 +0000[diff] [blame]122<li>AuroraUX / FreeBSD & OpenBSD Toolchain support.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]123<li>Many many bugs are fixed and many features have been added.</li>
124</ul>
125</div>
126
127<!--=========================================================================-->
128<div class="doc_subsection">
129<a name="clangsa">Clang Static Analyzer</a>
130</div>
131
132<div class="doc_text">
133
134<p>Previously announced in the 2.4 LLVM release, the Clang project also
135includes an early stage static source code analysis tool for <a
136href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
137in C and Objective-C programs. The tool performs a growing set of checks to find
138bugs that occur on a specific path within a program.</p>
139
140<p>In the LLVM 2.6 time-frame there have been many significant improvements to
141XYZ.</p>
142
143<p>The set of checks performed by the static analyzer continues to expand, and
144future plans for the tool include full source-level inter-procedural analysis
145and deeper checks such as buffer overrun detection. There are many opportunities
146to extend and enhance the static analyzer, and anyone interested in working on
147this project is encouraged to get involved!</p>
148
149</div>
150
151<!--=========================================================================-->
152<div class="doc_subsection">
153<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
154</div>
155
156<div class="doc_text">
157<p>
158The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
159a JVM and a CLI Virtual Machines (Microsoft .NET is an
160implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
161
162<p>Following LLVM 2.6, VMKit has its XYZ release that you can find on its
163<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
164bug fixes, cleanup and new features. The major changes are:</p>
165
166<ul>
167
168<li>Something wonderful!</li>
169
170</ul>
171</div>
172
173<!-- *********************************************************************** -->
174<div class="doc_section">
175 <a name="externalproj">External Projects Using LLVM 2.6</a>
176</div>
177<!-- *********************************************************************** -->
178
179<!--=========================================================================-->
180<div class="doc_subsection">
181<a name="pure">Pure</a>
182</div>
183
184<div class="doc_text">
185<p>
186<a href="http://pure-lang.googlecode.com/">Pure</a>
187is an algebraic/functional programming language based on term rewriting.
188Programs are collections of equations which are used to evaluate expressions in
189a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
190lexical closures, a hygienic macro system (also based on term rewriting),
191built-in list and matrix support (including list and matrix comprehensions) and
192an easy-to-use C interface. The interpreter uses LLVM as a backend to
193 JIT-compile Pure programs to fast native code.</p>
194
195<p>In addition to the usual algebraic data structures, Pure also has
196MATLAB-style matrices in order to support numeric computations and signal
197processing in an efficient way. Pure is mainly aimed at mathematical
198applications right now, but it has been designed as a general purpose language.
199The dynamic interpreter environment and the C interface make it possible to use
200it as a kind of functional scripting language for many application areas.
201</p>
202</div>
203
204
205<!--=========================================================================-->
206<div class="doc_subsection">
207<a name="ldc">LLVM D Compiler</a>
208</div>
209
210<div class="doc_text">
211<p>
212<a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
213the D Programming Language using the LLVM optimizer and code generator.
214The LDC project works great with the LLVM 2.6 release. General improvements in
215this
216cycle have included new inline asm constraint handling, better debug info
217support, general bugfixes, and better x86-64 support. This has allowed
218some major improvements in LDC, getting us much closer to being as
219fully featured as the original DMD compiler from DigitalMars.
220</p>
221</div>
222
223<!--=========================================================================-->
224<div class="doc_subsection">
225<a name="RoadsendPHP">Roadsend PHP</a>
226</div>
227
228<div class="doc_text">
229<p><a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
230source implementation of the PHP programming
231language that uses LLVM for its optimizer, JIT, and static compiler. This is a
232reimplementation of an earlier project that is now based on LLVM.</p>
233</div>
234
Jeffrey Yasskinba2aa782009-06-24 21:09:13 +0000[diff] [blame]235<!--=========================================================================-->
236<div class="doc_subsection">
237<a name="Unladen Swallow">Unladen Swallow</a>
238</div>
239
240<div class="doc_text">
241<p><a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
242branch of <a href="http://python.org/">Python</a> intended to be fully
243compatible and significantly faster. It uses LLVM's optimization passes and JIT
244compiler.</p>
245</div>
246
Jeffrey Yasskin5e98cb72009-06-24 21:26:42 +0000[diff] [blame]247<!--=========================================================================-->
248<div class="doc_subsection">
249<a name="Rubinius">Rubinius</a>
250</div>
251
252<div class="doc_text">
253<p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is a new virtual
254machine for Ruby. It leverages LLVM to dynamically compile Ruby code down to
255machine code using LLVM's JIT.</p>
256</div>
257
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]258
259<!-- *********************************************************************** -->
260<div class="doc_section">
261 <a name="whatsnew">What's New in LLVM 2.6?</a>
262</div>
263<!-- *********************************************************************** -->
264
265<div class="doc_text">
266
267<p>This release includes a huge number of bug fixes, performance tweaks, and
268minor improvements. Some of the major improvements and new features are listed
269in this section.
270</p>
271</div>
272
273<!--=========================================================================-->
274<div class="doc_subsection">
275<a name="majorfeatures">Major New Features</a>
276</div>
277
278<div class="doc_text">
279
280<p>LLVM 2.6 includes several major new capabilities:</p>
281
282<ul>
283<li>Something wonderful!</li>
Edward O'Callaghan50310f92009-08-22 02:17:22 +0000[diff] [blame]284<li>LLVM 2.6 includes a brand new experimental LLVM bindings to the Ada2005 programming language.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]285</ul>
286
287</div>
288
289
290<!--=========================================================================-->
291<div class="doc_subsection">
292<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
293</div>
294
295<div class="doc_text">
296
297<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
298front-ends and driver with the LLVM optimizer and code generator. It currently
299includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
300
301<ul>
302<li>Something wonderful!</li>
303</ul>
304
305</div>
306
307
308<!--=========================================================================-->
309<div class="doc_subsection">
310<a name="coreimprovements">LLVM IR and Core Improvements</a>
311</div>
312
313<div class="doc_text">
314<p>LLVM IR has several new features that are used by our existing front-ends and
315can be useful if you are writing a front-end for LLVM:</p>
316
317<ul>
318<li>Something wonderful!</li>
319</ul>
320
321</div>
322
323<!--=========================================================================-->
324<div class="doc_subsection">
325<a name="optimizer">Optimizer Improvements</a>
326</div>
327
328<div class="doc_text">
329
330<p>In addition to a large array of bug fixes and minor performance tweaks, this
331release includes a few major enhancements and additions to the optimizers:</p>
332
333<ul>
334
335<li>Something wonderful!</li>
336
337</ul>
338
339</div>
340
341<!--=========================================================================-->
342<div class="doc_subsection">
343<a name="codegen">Target Independent Code Generator Improvements</a>
344</div>
345
346<div class="doc_text">
347
348<p>We have put a significant amount of work into the code generator
349infrastructure, which allows us to implement more aggressive algorithms and make
350it run faster:</p>
351
352<ul>
353
354<li>Something wonderful!</li>
355</ul>
356</div>
357
358<!--=========================================================================-->
359<div class="doc_subsection">
360<a name="x86">X86-32 and X86-64 Target Improvements</a>
361</div>
362
363<div class="doc_text">
364<p>New features of the X86 target include:
365</p>
366
367<ul>
368
369<li>Something wonderful!</li>
370</ul>
371
372</div>
373
374<!--=========================================================================-->
375<div class="doc_subsection">
376<a name="pic16">PIC16 Target Improvements</a>
377</div>
378
379<div class="doc_text">
380<p>New features of the PIC16 target include:
381</p>
382
383<ul>
384<li>Something wonderful!</li>
385</ul>
386
387<p>Things not yet supported:</p>
388
389<ul>
390<li>Floating point.</li>
391<li>Passing/returning aggregate types to and from functions.</li>
392<li>Variable arguments.</li>
393<li>Indirect function calls.</li>
394<li>Interrupts/programs.</li>
395<li>Debug info.</li>
396</ul>
397
398</div>
399
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]400<!--=========================================================================-->
401<div class="doc_subsection">
402<a name="ARM">ARM Target Improvements</a>
403</div>
404
405<div class="doc_text">
406<p>New features of the ARM target include:
407</p>
408
409<ul>
410
411<li>Preliminary support for processors, such as the Cortex-A8 and Cortex-A9,
Sandeep Patel64e39612009-08-20 15:01:16 +0000[diff] [blame]412that implement version v7-A of the ARM architecture. The ARM backend now
413supports both the Thumb2 and Advanced SIMD (Neon) instruction sets. The
414AAPCS-VFP "hard float" calling conventions are also supported with the
415<tt>-float-abi=hard</tt> flag. These features are still somewhat experimental
416and subject to change. The Neon intrinsics, in particular, may change in future
417releases of LLVM.
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]418</li>
419</ul>
420
421</div>
422
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]423
424<!--=========================================================================-->
425<div class="doc_subsection">
426<a name="llvmc">Improvements in LLVMC</a>
427</div>
428
429<div class="doc_text">
430<p>New features include:</p>
431
432<ul>
433<li>Something wonderful!</li>
434</ul>
435
436</div>
437
438
439<!--=========================================================================-->
440<div class="doc_subsection">
441<a name="changes">Major Changes and Removed Features</a>
442</div>
443
444<div class="doc_text">
445
446<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]447on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]448from the previous release.</p>
449
450<ul>
451
452<li>Something horrible!</li>
453
454</ul>
455
456
457<p>In addition, many APIs have changed in this release. Some of the major LLVM
458API changes are:</p>
459
460<ul>
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]461<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
462 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
463 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
464 for clients that will only ever use a single context, the new
465 <tt>getGlobalContext()</tt> API can be used to access a default global
466 context which can be passed in any and all cases where a context is
467 required.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]468<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohmanf667e7e2009-07-07 20:05:15 +0000[diff] [blame]469<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
470 overloaded for floating-point types. Floating-point addition, subtraction,
471 and multiplication are now represented with new operators <tt>FAdd</tt>,
472 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
473 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
474 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
475 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
476 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbar02e73132009-07-12 20:41:27 +0000[diff] [blame]477<li>The DynamicLibrary class can no longer be constructed, its functionality has
478 moved to static member functions.</li>
Dan Gohmane4d54d72009-07-15 19:59:19 +0000[diff] [blame]479<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
480 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
481 <tt>false</tt>, an error will be reported if a file with the given name
482 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
483 be silently truncated (which is the behavior before this flag was
484 added).</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]485<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
486longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
487used.</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]488
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]489<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
490and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
491or <tt>std::string</tt>, as described in
492the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]493clients 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:
494 <ul>
495 <li><tt>getNameStr()</tt> is still available, and matches the old
496 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
497 although more efficient alternatives are now possible.</li>
498
499 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
500 a <tt>std::ostream</tt>, consider migrating
501 to <tt>llvm::raw_ostream</tt>.</li>
502
503 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
504 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
505 Note that this string (as before), may not be the entire name if the
506 name containts embedded null characters.</li>
507
508 <li>If you were using operator plus on the result of <tt>getName()</tt> and
509 treating the result as an <tt>std::string</tt>, you can either
510 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
511 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbar03d76512009-07-25 23:55:21 +0000[diff] [blame]512
513 <li><tt>isName()</tt> should be replaced with comparison
Benjamin Kramere15192b2009-08-05 15:42:44 +0000[diff] [blame]514 against <tt>getName()</tt> (this is now efficient).
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]515 </ul>
516</li>
517
Daniel Dunbara5881e32009-07-26 02:12:58 +0000[diff] [blame]518<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbard6b06b12009-07-26 05:41:39 +0000[diff] [blame]519previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
520 <ul>
521 <li><tt>TargetMachineRegistry</tt> has been renamed
522 to <tt>TargetRegistry</tt>.</li>
523
524 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
525 function to find targets.</li>
526 </ul>
527</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]528
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]529<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]530FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
531This is not an API change, maybe there should be a tool changes section?</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]532<li>temporarely due to Context API change passes should call doInitialization()
533method of the pass they inherit from, otherwise Context is NULL.
534FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]535</ul>
536
537</div>
538
539
540
541<!-- *********************************************************************** -->
542<div class="doc_section">
543 <a name="portability">Portability and Supported Platforms</a>
544</div>
545<!-- *********************************************************************** -->
546
547<div class="doc_text">
548
549<p>LLVM is known to work on the following platforms:</p>
550
551<ul>
552<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]553Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]554<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
555and 64-bit modes.</li>
556<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
557<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
558 support is available for native builds with Visual C++).</li>
559<li>Sun UltraSPARC workstations running Solaris 10.</li>
560<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]561</ul>
562
563<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
564to the machine and operating system on which it is built. However, minor
565porting may be required to get LLVM to work on new platforms. We welcome your
566portability patches and reports of successful builds or error messages.</p>
567
568</div>
569
570<!-- *********************************************************************** -->
571<div class="doc_section">
572 <a name="knownproblems">Known Problems</a>
573</div>
574<!-- *********************************************************************** -->
575
576<div class="doc_text">
577
578<p>This section contains significant known problems with the LLVM system,
579listed by component. If you run into a problem, please check the <a
580href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
581there isn't already one.</p>
582
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]583<ul>
Chris Lattneraedb59a2009-07-21 23:17:26 +0000[diff] [blame]584<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]585using the stock GCC 3.x.x series 'out the box',
586See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
587However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
588for x86/x64 has been made available from the third party AuroraUX Project
589that has been meticulously tested for bootstrapping LLVM & Clang.</li>
590</ul>
591
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]592</div>
593
594<!-- ======================================================================= -->
595<div class="doc_subsection">
596 <a name="experimental">Experimental features included with this release</a>
597</div>
598
599<div class="doc_text">
600
601<p>The following components of this LLVM release are either untested, known to
602be broken or unreliable, or are in early development. These components should
603not be relied on, and bugs should not be filed against them, but they may be
604useful to some people. In particular, if you would like to work on one of these
605components, please contact us on the <a
606href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
607
608<ul>
Dan Gohmand2cb3d22009-07-24 00:30:09 +0000[diff] [blame]609<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]610<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
611 supported value for this option.</li>
612</ul>
613
614</div>
615
616<!-- ======================================================================= -->
617<div class="doc_subsection">
618 <a name="x86-be">Known problems with the X86 back-end</a>
619</div>
620
621<div class="doc_text">
622
623<ul>
624 <li>The X86 backend does not yet support
625 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
626 floating point stack</a>. It supports the 'f' and 't' constraints, but not
627 'u'.</li>
628 <li>The X86 backend generates inefficient floating point code when configured
629 to generate code for systems that don't have SSE2.</li>
630 <li>Win64 code generation wasn't widely tested. Everything should work, but we
631 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
632 runtime currently due
633 to <a href="http://llvm.org/PR2255">several</a>
634 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
635 the
636 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
637 <li>The X86-64 backend does not yet support the LLVM IR instruction
638 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
639 argument constructs on X86-64 by lowering them manually.</li>
640</ul>
641
642</div>
643
644<!-- ======================================================================= -->
645<div class="doc_subsection">
646 <a name="ppc-be">Known problems with the PowerPC back-end</a>
647</div>
648
649<div class="doc_text">
650
651<ul>
652<li>The Linux PPC32/ABI support needs testing for the interpreter and static
653compilation, and lacks support for debug information.</li>
654</ul>
655
656</div>
657
658<!-- ======================================================================= -->
659<div class="doc_subsection">
660 <a name="arm-be">Known problems with the ARM back-end</a>
661</div>
662
663<div class="doc_text">
664
665<ul>
Bob Wilson755cbe02009-08-12 21:19:49 +0000[diff] [blame]666<li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
667and not well tested. Some features may not work at all, and the code quality
668may be poor in some cases.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]669<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
670processors, thumb programs can crash or produce wrong
671results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
672<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
673</li>
674<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
675 execute
676programs compiled with LLVM. Please use more recent versions of QEMU.</li>
677</ul>
678
679</div>
680
681<!-- ======================================================================= -->
682<div class="doc_subsection">
683 <a name="sparc-be">Known problems with the SPARC back-end</a>
684</div>
685
686<div class="doc_text">
687
688<ul>
689<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
690 support the 64-bit SPARC ABI (-m64).</li>
691</ul>
692
693</div>
694
695<!-- ======================================================================= -->
696<div class="doc_subsection">
697 <a name="mips-be">Known problems with the MIPS back-end</a>
698</div>
699
700<div class="doc_text">
701
702<ul>
703<li>The O32 ABI is not fully supported.</li>
704<li>64-bit MIPS targets are not supported yet.</li>
705</ul>
706
707</div>
708
709<!-- ======================================================================= -->
710<div class="doc_subsection">
711 <a name="alpha-be">Known problems with the Alpha back-end</a>
712</div>
713
714<div class="doc_text">
715
716<ul>
717
718<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
719appropriate nops inserted to ensure restartability.</li>
720
721</ul>
722</div>
723
724<!-- ======================================================================= -->
725<div class="doc_subsection">
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]726 <a name="c-be">Known problems with the C back-end</a>
727</div>
728
729<div class="doc_text">
730
731<ul>
732<li><a href="http://llvm.org/PR802">The C backend has only basic support for
733 inline assembly code</a>.</li>
734<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
735 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
736 C++ code compiled with <tt>llc</tt> or native compilers.</li>
737<li>The C backend does not support all exception handling constructs.</li>
738<li>The C backend does not support arbitrary precision integers.</li>
739</ul>
740
741</div>
742
743
744<!-- ======================================================================= -->
745<div class="doc_subsection">
746 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
747</div>
748
749<div class="doc_text">
750
751<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
752Optimization</a> on most platforms "out-of-the-box". Please inquire on the
753LLVMdev mailing list if you are interested.</p>
754
755<p>The only major language feature of GCC not supported by llvm-gcc is
756 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
757 are only supported on some targets. For example, trampolines are only
758 supported on some targets (these are used when you take the address of a
759 nested function).</p>
760
761<p>If you run into GCC extensions which are not supported, please let us know.
762</p>
763
764</div>
765
766<!-- ======================================================================= -->
767<div class="doc_subsection">
768 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
769</div>
770
771<div class="doc_text">
772
773<p>The C++ front-end is considered to be fully
774tested and works for a number of non-trivial programs, including LLVM
775itself, Qt, Mozilla, etc.</p>
776
777<ul>
778<li>Exception handling works well on the X86 and PowerPC targets. Currently
779 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
780</ul>
781
782</div>
783
784<!-- ======================================================================= -->
785<div class="doc_subsection">
786 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
787</div>
788
789<div class="doc_text">
790<ul>
791<li>Fortran support generally works, but there are still several unresolved bugs
792 in Bugzilla. Please see the tools/gfortran component for details.</li>
793</ul>
794</div>
795
796<!-- ======================================================================= -->
797<div class="doc_subsection">
798 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
799</div>
800
801<div class="doc_text">
802The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
803technology, and problems should be expected.
804<ul>
805<li>The Ada front-end currently only builds on X86-32. This is mainly due
806to lack of trampoline support (pointers to nested functions) on other platforms.
807However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
808which does support trampolines.</li>
809<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
810This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
811exception handling, which is used internally by the compiler.
812Workaround: configure with --disable-bootstrap.</li>
813<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
814and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
815(c380004 also fails with gcc-4.2 mainline).
816If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
817causes the compiler to go into an infinite loop, using up all system memory.</li>
818<li>Some GCC specific Ada tests continue to crash the compiler.</li>
819<li>The -E binder option (exception backtraces)
820<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
821crashing if an exception is raised. Workaround: do not use -E.</li>
822<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
823or finish at a non-byte offset</a> in a record. Workaround: do not pack records
824or use representation clauses that result in a field of a non-discrete type
825starting or finishing in the middle of a byte.</li>
826<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
827'main' as generated by the Ada binder to be invalid</a>.
828Workaround: hand edit the file to use pointers for <tt>argv</tt> and
829<tt>envp</tt> rather than integers.</li>
830<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
831ignored</a>.</li>
832</ul>
833</div>
834
835<!-- *********************************************************************** -->
836<div class="doc_section">
837 <a name="additionalinfo">Additional Information</a>
838</div>
839<!-- *********************************************************************** -->
840
841<div class="doc_text">
842
843<p>A wide variety of additional information is available on the <a
844href="http://llvm.org">LLVM web page</a>, in particular in the <a
845href="http://llvm.org/docs/">documentation</a> section. The web page also
846contains versions of the API documentation which is up-to-date with the
847Subversion version of the source code.
848You can access versions of these documents specific to this release by going
849into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
850
851<p>If you have any questions or comments about LLVM, please feel free to contact
852us via the <a href="http://llvm.org/docs/#maillist"> mailing
853lists</a>.</p>
854
855</div>
856
857<!-- *********************************************************************** -->
858
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