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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>
463<li>llvm-dis now fails if output file exists, instead of dumping to stdout.
464FIXME: describe any other tool changes due to the raw_fd_ostream change</li>
465<li>temporarely due to Context API change passes should call doInitialization()
466method of the pass they inherit from, otherwise Context is NULL.
467FIXME: remove this entry when this is no longer needed.<li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]468</ul>
469
470</div>
471
472
473
474<!-- *********************************************************************** -->
475<div class="doc_section">
476 <a name="portability">Portability and Supported Platforms</a>
477</div>
478<!-- *********************************************************************** -->
479
480<div class="doc_text">
481
482<p>LLVM is known to work on the following platforms:</p>
483
484<ul>
485<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame^]486Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like systems).</li>
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]487<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
488and 64-bit modes.</li>
489<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
490<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
491 support is available for native builds with Visual C++).</li>
492<li>Sun UltraSPARC workstations running Solaris 10.</li>
493<li>Alpha-based machines running Debian GNU/Linux.</li>
494<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
495</ul>
496
497<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
498to the machine and operating system on which it is built. However, minor
499porting may be required to get LLVM to work on new platforms. We welcome your
500portability patches and reports of successful builds or error messages.</p>
501
502</div>
503
504<!-- *********************************************************************** -->
505<div class="doc_section">
506 <a name="knownproblems">Known Problems</a>
507</div>
508<!-- *********************************************************************** -->
509
510<div class="doc_text">
511
512<p>This section contains significant known problems with the LLVM system,
513listed by component. If you run into a problem, please check the <a
514href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
515there isn't already one.</p>
516
Chris Lattner3e7b5ca2009-07-21 22:47:03 +0000[diff] [blame^]517<ul>
518<li>LLVM will not correctly complie on Solaris and/or OpenSolaris
519using the stock GCC 3.x.x series 'out the box',
520See: <a href="#brokengcc">Broken versions of GCC and other tools</a>.
521However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
522for x86/x64 has been made available from the third party AuroraUX Project
523that has been meticulously tested for bootstrapping LLVM & Clang.</li>
524</ul>
525
Duncan Sandse2e4a892009-06-24 08:38:48 +0000[diff] [blame]526</div>
527
528<!-- ======================================================================= -->
529<div class="doc_subsection">
530 <a name="experimental">Experimental features included with this release</a>
531</div>
532
533<div class="doc_text">
534
535<p>The following components of this LLVM release are either untested, known to
536be broken or unreliable, or are in early development. These components should
537not be relied on, and bugs should not be filed against them, but they may be
538useful to some people. In particular, if you would like to work on one of these
539components, please contact us on the <a
540href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
541
542<ul>
543<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
544<li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
545 supported value for this option.</li>
546</ul>
547
548</div>
549
550<!-- ======================================================================= -->
551<div class="doc_subsection">
552 <a name="x86-be">Known problems with the X86 back-end</a>
553</div>
554
555<div class="doc_text">
556
557<ul>
558 <li>The X86 backend does not yet support
559 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
560 floating point stack</a>. It supports the 'f' and 't' constraints, but not
561 'u'.</li>
562 <li>The X86 backend generates inefficient floating point code when configured
563 to generate code for systems that don't have SSE2.</li>
564 <li>Win64 code generation wasn't widely tested. Everything should work, but we
565 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
566 runtime currently due
567 to <a href="http://llvm.org/PR2255">several</a>
568 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
569 the
570 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
571 <li>The X86-64 backend does not yet support the LLVM IR instruction
572 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
573 argument constructs on X86-64 by lowering them manually.</li>
574</ul>
575
576</div>
577
578<!-- ======================================================================= -->
579<div class="doc_subsection">
580 <a name="ppc-be">Known problems with the PowerPC back-end</a>
581</div>
582
583<div class="doc_text">
584
585<ul>
586<li>The Linux PPC32/ABI support needs testing for the interpreter and static
587compilation, and lacks support for debug information.</li>
588</ul>
589
590</div>
591
592<!-- ======================================================================= -->
593<div class="doc_subsection">
594 <a name="arm-be">Known problems with the ARM back-end</a>
595</div>
596
597<div class="doc_text">
598
599<ul>
600<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
601processors, thumb programs can crash or produce wrong
602results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
603<li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
604</li>
605<li>There is a bug in QEMU-ARM (&lt;= 0.9.0) which causes it to incorrectly
606 execute
607programs compiled with LLVM. Please use more recent versions of QEMU.</li>
608</ul>
609
610</div>
611
612<!-- ======================================================================= -->
613<div class="doc_subsection">
614 <a name="sparc-be">Known problems with the SPARC back-end</a>
615</div>
616
617<div class="doc_text">
618
619<ul>
620<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
621 support the 64-bit SPARC ABI (-m64).</li>
622</ul>
623
624</div>
625
626<!-- ======================================================================= -->
627<div class="doc_subsection">
628 <a name="mips-be">Known problems with the MIPS back-end</a>
629</div>
630
631<div class="doc_text">
632
633<ul>
634<li>The O32 ABI is not fully supported.</li>
635<li>64-bit MIPS targets are not supported yet.</li>
636</ul>
637
638</div>
639
640<!-- ======================================================================= -->
641<div class="doc_subsection">
642 <a name="alpha-be">Known problems with the Alpha back-end</a>
643</div>
644
645<div class="doc_text">
646
647<ul>
648
649<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
650appropriate nops inserted to ensure restartability.</li>
651
652</ul>
653</div>
654
655<!-- ======================================================================= -->
656<div class="doc_subsection">
657 <a name="ia64-be">Known problems with the IA64 back-end</a>
658</div>
659
660<div class="doc_text">
661
662<ul>
663<li>The Itanium backend is highly experimental and has a number of known
664 issues. We are looking for a maintainer for the Itanium backend. If you
665 are interested, please contact the LLVMdev mailing list.</li>
666</ul>
667
668</div>
669
670<!-- ======================================================================= -->
671<div class="doc_subsection">
672 <a name="c-be">Known problems with the C back-end</a>
673</div>
674
675<div class="doc_text">
676
677<ul>
678<li><a href="http://llvm.org/PR802">The C backend has only basic support for
679 inline assembly code</a>.</li>
680<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
681 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
682 C++ code compiled with <tt>llc</tt> or native compilers.</li>
683<li>The C backend does not support all exception handling constructs.</li>
684<li>The C backend does not support arbitrary precision integers.</li>
685</ul>
686
687</div>
688
689
690<!-- ======================================================================= -->
691<div class="doc_subsection">
692 <a name="c-fe">Known problems with the llvm-gcc C front-end</a>
693</div>
694
695<div class="doc_text">
696
697<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
698Optimization</a> on most platforms "out-of-the-box". Please inquire on the
699LLVMdev mailing list if you are interested.</p>
700
701<p>The only major language feature of GCC not supported by llvm-gcc is
702 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
703 are only supported on some targets. For example, trampolines are only
704 supported on some targets (these are used when you take the address of a
705 nested function).</p>
706
707<p>If you run into GCC extensions which are not supported, please let us know.
708</p>
709
710</div>
711
712<!-- ======================================================================= -->
713<div class="doc_subsection">
714 <a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
715</div>
716
717<div class="doc_text">
718
719<p>The C++ front-end is considered to be fully
720tested and works for a number of non-trivial programs, including LLVM
721itself, Qt, Mozilla, etc.</p>
722
723<ul>
724<li>Exception handling works well on the X86 and PowerPC targets. Currently
725 only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
726</ul>
727
728</div>
729
730<!-- ======================================================================= -->
731<div class="doc_subsection">
732 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
733</div>
734
735<div class="doc_text">
736<ul>
737<li>Fortran support generally works, but there are still several unresolved bugs
738 in Bugzilla. Please see the tools/gfortran component for details.</li>
739</ul>
740</div>
741
742<!-- ======================================================================= -->
743<div class="doc_subsection">
744 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
745</div>
746
747<div class="doc_text">
748The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
749technology, and problems should be expected.
750<ul>
751<li>The Ada front-end currently only builds on X86-32. This is mainly due
752to lack of trampoline support (pointers to nested functions) on other platforms.
753However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
754which does support trampolines.</li>
755<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
756This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
757exception handling, which is used internally by the compiler.
758Workaround: configure with --disable-bootstrap.</li>
759<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
760and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
761(c380004 also fails with gcc-4.2 mainline).
762If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
763causes the compiler to go into an infinite loop, using up all system memory.</li>
764<li>Some GCC specific Ada tests continue to crash the compiler.</li>
765<li>The -E binder option (exception backtraces)
766<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
767crashing if an exception is raised. Workaround: do not use -E.</li>
768<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
769or finish at a non-byte offset</a> in a record. Workaround: do not pack records
770or use representation clauses that result in a field of a non-discrete type
771starting or finishing in the middle of a byte.</li>
772<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
773'main' as generated by the Ada binder to be invalid</a>.
774Workaround: hand edit the file to use pointers for <tt>argv</tt> and
775<tt>envp</tt> rather than integers.</li>
776<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
777ignored</a>.</li>
778</ul>
779</div>
780
781<!-- *********************************************************************** -->
782<div class="doc_section">
783 <a name="additionalinfo">Additional Information</a>
784</div>
785<!-- *********************************************************************** -->
786
787<div class="doc_text">
788
789<p>A wide variety of additional information is available on the <a
790href="http://llvm.org">LLVM web page</a>, in particular in the <a
791href="http://llvm.org/docs/">documentation</a> section. The web page also
792contains versions of the API documentation which is up-to-date with the
793Subversion version of the source code.
794You can access versions of these documents specific to this release by going
795into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
796
797<p>If you have any questions or comments about LLVM, please feel free to contact
798us via the <a href="http://llvm.org/docs/#maillist"> mailing
799lists</a>.</p>
800
801</div>
802
803<!-- *********************************************************************** -->
804
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