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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
398
399<!--=========================================================================-->
400<div class="doc_subsection">
401<a name="llvmc">Improvements in LLVMC</a>
402</div>
403
404<div class="doc_text">
405<p>New features include:</p>
406
407<ul>
408<li>Something wonderful!</li>
409</ul>
410
411</div>
412
413
414<!--=========================================================================-->
415<div class="doc_subsection">
416<a name="changes">Major Changes and Removed Features</a>
417</div>
418
419<div class="doc_text">
420
421<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]422on LLVM 2.5, this section lists some "gotchas" that you may run into upgrading
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]423from the previous release.</p>
424
425<ul>
426
427<li>Something horrible!</li>
428
429</ul>
430
431
432<p>In addition, many APIs have changed in this release. Some of the major LLVM
433API changes are:</p>
434
435<ul>
Owen Andersone27be3a2009-07-02 16:48:38 +0000[diff] [blame]436<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
437 been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
438 now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
439 for clients that will only ever use a single context, the new
440 <tt>getGlobalContext()</tt> API can be used to access a default global
441 context which can be passed in any and all cases where a context is
442 required.
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]443<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
Dan Gohmanf667e7e2009-07-07 20:05:15 +0000[diff] [blame]444<li>The <tt>Add</tt>, <tt>Sub</tt>, and <tt>Mul</tt> operators are no longer
445 overloaded for floating-point types. Floating-point addition, subtraction,
446 and multiplication are now represented with new operators <tt>FAdd</tt>,
447 <tt>FSub</tt>, and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
448 <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt>, and
449 <tt>CreateNeg</tt> should only be used for integer arithmetic now;
450 <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt>, and
451 <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
Daniel Dunbar02e73132009-07-12 20:41:27 +0000[diff] [blame]452<li>The DynamicLibrary class can no longer be constructed, its functionality has
453 moved to static member functions.</li>
Dan Gohmane4d54d72009-07-15 19:59:19 +0000[diff] [blame]454<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
455 takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
456 <tt>false</tt>, an error will be reported if a file with the given name
457 already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
458 be silently truncated (which is the behavior before this flag was
459 added).</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]460<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
461longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt> should be
462used.</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]463
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]464<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
465and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
466or <tt>std::string</tt>, as described in
467the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]468clients 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:
469 <ul>
470 <li><tt>getNameStr()</tt> is still available, and matches the old
471 behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
472 although more efficient alternatives are now possible.</li>
473
474 <li>If you were just relying on <tt>getName()</tt> being able to be sent to
475 a <tt>std::ostream</tt>, consider migrating
476 to <tt>llvm::raw_ostream</tt>.</li>
477
478 <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
479 char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
480 Note that this string (as before), may not be the entire name if the
481 name containts embedded null characters.</li>
482
483 <li>If you were using operator plus on the result of <tt>getName()</tt> and
484 treating the result as an <tt>std::string</tt>, you can either
485 uses <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
486 could move to a <tt>Twine</tt> based design.</li>
Daniel Dunbar03d76512009-07-25 23:55:21 +0000[diff] [blame]487
488 <li><tt>isName()</tt> should be replaced with comparison
489 against <tt>getName()</tt> (this is now efficient).</tt>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]490 </ul>
491</li>
492
Daniel Dunbara5881e32009-07-26 02:12:58 +0000[diff] [blame]493<li>The registration interfaces for backend Targets has changed (what was
Daniel Dunbard6b06b12009-07-26 05:41:39 +0000[diff] [blame]494previously TargetMachineRegistry). For backend authors, see the <a href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a> guide. For clients, the notable API changes are:
495 <ul>
496 <li><tt>TargetMachineRegistry</tt> has been renamed
497 to <tt>TargetRegistry</tt>.</li>
498
499 <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
500 function to find targets.</li>
501 </ul>
502</li>
Daniel Dunbar8b5ee822009-07-25 05:26:53 +0000[diff] [blame]503
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]504<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
Daniel Dunbar6e0d1cb2009-07-25 04:41:11 +0000[diff] [blame]505FIXME: describe any other tool changes due to the raw_fd_ostream change. FIXME:
506This is not an API change, maybe there should be a tool changes section?</li>
Torok Edwinf6fa8ae2009-07-21 20:27:10 +0000[diff] [blame]507<li>temporarely due to Context API change passes should call doInitialization()
508method of the pass they inherit from, otherwise Context is NULL.
509FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]510</ul>
511
512</div>
513
514
515
516<!-- *********************************************************************** -->
517<div class="doc_section">
518 <a name="portability">Portability and Supported Platforms</a>
519</div>
520<!-- *********************************************************************** -->
521
522<div class="doc_text">
523
524<p>LLVM is known to work on the following platforms:</p>
525
526<ul>
527<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]528Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]529<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
530and 64-bit modes.</li>
531<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
532<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
533 support is available for native builds with Visual C++).</li>
534<li>Sun UltraSPARC workstations running Solaris 10.</li>
535<li>Alpha-based machines running Debian GNU/Linux.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]536</ul>
537
538<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
539to the machine and operating system on which it is built. However, minor
540porting may be required to get LLVM to work on new platforms. We welcome your
541portability patches and reports of successful builds or error messages.</p>
542
543</div>
544
545<!-- *********************************************************************** -->
546<div class="doc_section">
547 <a name="knownproblems">Known Problems</a>
548</div>
549<!-- *********************************************************************** -->
550
551<div class="doc_text">
552
553<p>This section contains significant known problems with the LLVM system,
554listed by component. If you run into a problem, please check the <a
555href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
556there isn't already one.</p>
557
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]558<ul>
Chris Lattneraedb59a2009-07-21 23:17:26 +0000[diff] [blame]559<li>LLVM will not correctly compile on Solaris and/or OpenSolaris
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame]560using the stock GCC 3.x.x series 'out the box',
561See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
562However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
563for x86/x64 has been made available from the third party AuroraUX Project
564that has been meticulously tested for bootstrapping LLVM & Clang.</li>
565</ul>
566
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]567</div>
568
569<!-- ======================================================================= -->
570<div class="doc_subsection">
571 <a name="experimental">Experimental features included with this release</a>
572</div>
573
574<div class="doc_text">
575
576<p>The following components of this LLVM release are either untested, known to
577be broken or unreliable, or are in early development. These components should
578not be relied on, and bugs should not be filed against them, but they may be
579useful to some people. In particular, if you would like to work on one of these
580components, please contact us on the <a
581href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
582
583<ul>
Dan Gohmand2cb3d22009-07-24 00:30:09 +0000[diff] [blame]584<li>The MSIL, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]585<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
586 supported value for this option.</li>
587</ul>
588
589</div>
590
591<!-- ======================================================================= -->
592<div class="doc_subsection">
593 <a name="x86-be">Known problems with the X86 back-end</a>
594</div>
595
596<div class="doc_text">
597
598<ul>
599 <li>The X86 backend does not yet support
600 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
601 floating point stack</a>. It supports the 'f' and 't' constraints, but not
602 'u'.</li>
603 <li>The X86 backend generates inefficient floating point code when configured
604 to generate code for systems that don't have SSE2.</li>
605 <li>Win64 code generation wasn't widely tested. Everything should work, but we
606 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
607 runtime currently due
608 to <a href="http://llvm.org/PR2255">several</a>
609 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
610 the
611 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
612 <li>The X86-64 backend does not yet support the LLVM IR instruction
613 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
614 argument constructs on X86-64 by lowering them manually.</li>
615</ul>
616
617</div>
618
619<!-- ======================================================================= -->
620<div class="doc_subsection">
621 <a name="ppc-be">Known problems with the PowerPC back-end</a>
622</div>
623
624<div class="doc_text">
625
626<ul>
627<li>The Linux PPC32/ABI support needs testing for the interpreter and static
628compilation, and lacks support for debug information.</li>
629</ul>
630
631</div>
632
633<!-- ======================================================================= -->
634<div class="doc_subsection">
635 <a name="arm-be">Known problems with the ARM back-end</a>
636</div>
637
638<div class="doc_text">
639
640<ul>
641<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
642processors, thumb programs can crash or produce wrong
643results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
644<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
645</li>
646<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
647 execute
648programs compiled with LLVM. Please use more recent versions of QEMU.</li>
649</ul>
650
651</div>
652
653<!-- ======================================================================= -->
654<div class="doc_subsection">
655 <a name="sparc-be">Known problems with the SPARC back-end</a>
656</div>
657
658<div class="doc_text">
659
660<ul>
661<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
662 support the 64-bit SPARC ABI (-m64).</li>
663</ul>
664
665</div>
666
667<!-- ======================================================================= -->
668<div class="doc_subsection">
669 <a name="mips-be">Known problems with the MIPS back-end</a>
670</div>
671
672<div class="doc_text">
673
674<ul>
675<li>The O32 ABI is not fully supported.</li>
676<li>64-bit MIPS targets are not supported yet.</li>
677</ul>
678
679</div>
680
681<!-- ======================================================================= -->
682<div class="doc_subsection">
683 <a name="alpha-be">Known problems with the Alpha back-end</a>
684</div>
685
686<div class="doc_text">
687
688<ul>
689
690<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
691appropriate nops inserted to ensure restartability.</li>
692
693</ul>
694</div>
695
696<!-- ======================================================================= -->
697<div class="doc_subsection">
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]698 <a name="c-be">Known problems with the C back-end</a>
699</div>
700
701<div class="doc_text">
702
703<ul>
704<li><a href="http://llvm.org/PR802">The C backend has only basic support for
705 inline assembly code</a>.</li>
706<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
707 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
708 C++ code compiled with <tt>llc</tt> or native compilers.</li>
709<li>The C backend does not support all exception handling constructs.</li>
710<li>The C backend does not support arbitrary precision integers.</li>
711</ul>
712
713</div>
714
715
716<!-- ======================================================================= -->
717<div class="doc_subsection">
718 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
719</div>
720
721<div class="doc_text">
722
723<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
724Optimization</a> on most platforms "out-of-the-box". Please inquire on the
725LLVMdev mailing list if you are interested.</p>
726
727<p>The only major language feature of GCC not supported by llvm-gcc is
728 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
729 are only supported on some targets. For example, trampolines are only
730 supported on some targets (these are used when you take the address of a
731 nested function).</p>
732
733<p>If you run into GCC extensions which are not supported, please let us know.
734</p>
735
736</div>
737
738<!-- ======================================================================= -->
739<div class="doc_subsection">
740 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
741</div>
742
743<div class="doc_text">
744
745<p>The C++ front-end is considered to be fully
746tested and works for a number of non-trivial programs, including LLVM
747itself, Qt, Mozilla, etc.</p>
748
749<ul>
750<li>Exception handling works well on the X86 and PowerPC targets. Currently
751 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
752</ul>
753
754</div>
755
756<!-- ======================================================================= -->
757<div class="doc_subsection">
758 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
759</div>
760
761<div class="doc_text">
762<ul>
763<li>Fortran support generally works, but there are still several unresolved bugs
764 in Bugzilla. Please see the tools/gfortran component for details.</li>
765</ul>
766</div>
767
768<!-- ======================================================================= -->
769<div class="doc_subsection">
770 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
771</div>
772
773<div class="doc_text">
774The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
775technology, and problems should be expected.
776<ul>
777<li>The Ada front-end currently only builds on X86-32. This is mainly due
778to lack of trampoline support (pointers to nested functions) on other platforms.
779However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
780which does support trampolines.</li>
781<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
782This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
783exception handling, which is used internally by the compiler.
784Workaround: configure with --disable-bootstrap.</li>
785<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
786and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
787(c380004 also fails with gcc-4.2 mainline).
788If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
789causes the compiler to go into an infinite loop, using up all system memory.</li>
790<li>Some GCC specific Ada tests continue to crash the compiler.</li>
791<li>The -E binder option (exception backtraces)
792<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
793crashing if an exception is raised. Workaround: do not use -E.</li>
794<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
795or finish at a non-byte offset</a> in a record. Workaround: do not pack records
796or use representation clauses that result in a field of a non-discrete type
797starting or finishing in the middle of a byte.</li>
798<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
799'main' as generated by the Ada binder to be invalid</a>.
800Workaround: hand edit the file to use pointers for <tt>argv</tt> and
801<tt>envp</tt> rather than integers.</li>
802<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
803ignored</a>.</li>
804</ul>
805</div>
806
807<!-- *********************************************************************** -->
808<div class="doc_section">
809 <a name="additionalinfo">Additional Information</a>
810</div>
811<!-- *********************************************************************** -->
812
813<div class="doc_text">
814
815<p>A wide variety of additional information is available on the <a
816href="http://llvm.org">LLVM web page</a>, in particular in the <a
817href="http://llvm.org/docs/">documentation</a> section. The web page also
818contains versions of the API documentation which is up-to-date with the
819Subversion version of the source code.
820You can access versions of these documents specific to this release by going
821into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
822
823<p>If you have any questions or comments about LLVM, please feel free to contact
824us via the <a href="http://llvm.org/docs/#maillist"> mailing
825lists</a>.</p>
826
827</div>
828
829<!-- *********************************************************************** -->
830
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