Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 41bf8e96d6376b5403d3b25daae0c262151c975f / . / docs / ReleaseNotes.html
blob: c8c0bd375f8c100acc27f38fcfdcf1ee48079ca0 [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css">
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]7 <title>LLVM 2.2 Release Notes</title>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]8</head>
9<body>
10
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]11<div class="doc_title">LLVM 2.2 Release Notes</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]12
13<ol>
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
17 <li><a href="#portability">Portability and Supported Platforms</a></li>
18 <li><a href="#knownproblems">Known Problems</a>
19 <li><a href="#additionalinfo">Additional Information</a></li>
20</ol>
21
22<div class="doc_author">
23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
24</div>
25
Chris Lattner92bd6442008-02-06 18:00:48 +0000[diff] [blame]26<h1><font color="red">THIS IS A WORK IN PROGRESS FOR THE LLVM 2.2
27RELEASE</font</h1>
28
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]29<!-- *********************************************************************** -->
30<div class="doc_section">
31 <a name="intro">Introduction</a>
32</div>
33<!-- *********************************************************************** -->
34
35<div class="doc_text">
36
37<p>This document contains the release notes for the LLVM compiler
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]38infrastructure, release 2.2. Here we describe the status of LLVM, including
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]39major improvements from the previous release and any known problems. All LLVM
40releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
41releases web site</a>.</p>
42
43<p>For more information about LLVM, including information about the latest
44release, please check out the <a href="http://llvm.org/">main LLVM
45web site</a>. If you have questions or comments, the <a
46href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
47list</a> is a good place to send them.</p>
48
49<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]50main LLVM web page, this document applies to the <i>next</i> release, not the
51current one. To see the release notes for a specific releases, please see the
52<a href="http://llvm.org/releases/">releases page</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]53
54</div>
55
56<!-- *********************************************************************** -->
57<div class="doc_section">
58 <a name="whatsnew">What's New?</a>
59</div>
60<!-- *********************************************************************** -->
61
62<div class="doc_text">
63
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]64<p>This is the thirteenth public release of the LLVM Compiler Infrastructure.
65It includes many features and refinements from LLVM 2.1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]66
67</div>
68
69<!--=========================================================================-->
70<div class="doc_subsection">
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]71<a name="deprecation">Deprecated features in LLVM 2.2</a>
72</div>
73
74<div class="doc_text">
75
76<p>This is the last LLVM release to support llvm-gcc 4.0, llvm-upgrade, and
77llvmc in its current form. llvm-gcc 4.0 has been replaced with llvm-gcc 4.2.
78llvm-upgrade is useful for upgrading llvm 1.9 files to llvm 2.x syntax, but you
79can always use an old release to do this. llvmc is currently mostly useless in
80llvm 2.2, and will be redesigned or removed in llvm 2.3.</p>
81
82</div>
83
84<!--=========================================================================-->
85<div class="doc_subsection">
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]86<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]87</div>
88
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]89<div class="doc_text">
90
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]91<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
92LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
93has made leaps and bounds and is now at least as good as 4.0 in virtually every
94area, and is better in several areas (for example, exception handling
95correctness). We strongly recommend that you migrate from llvm-gcc 4.0 to
96llvm-gcc 4.2 in this release cycle because <b>LLVM 2.2 is the last release
97that will support llvm-gcc 4.0</b>: LLVM 2.3 will only support the llvm-gcc
984.2 front-end.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]99
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]100<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
101a set of new 'llvm native' front-end technologies for the LLVM optimizer
102and code generator. Currently, its C and Objective-C support is maturing
103nicely, and it has advanced source-to-source analysis and transformation
104capabilities. If you are interested in building source-level tools for C and
105Objective-C (and eventually C++), you should take a look. However, note that
106clang is not an official part of the LLVM 2.2 release. If you are interested in
107this project, please see the web site.</p>
108
109</div>
110
111<!--=========================================================================-->
112<div class="doc_subsection">
113<a name="majorfeatures">Major New Features</a>
114</div>
115
116<div class="doc_text">
117
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]118<p>Scott Michel contributed Cell backend</p>
119
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]120<p>Dale contributed full support for long double on x86/x86-64 (where it is 80
121bits) and on Darwin PPC/PPC64 (where it is 128 bits).</p>
122
123<p>Ada, gfortran</p>
124
125<p>
126debug improvements -O0
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]127
128Gordon: GC Revamp. docs/GarbageCollection.html
129
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]130Kaleidoscope: docs/tutorial
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]131
132Gordon: C and Ocaml Bindings
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]133
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]134Christopher Lamb: Multiple address spaces.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]135</div>
136
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]137<!--=========================================================================-->
138<div class="doc_subsection">
139<a name="optimizer">Optimizer Improvements</a>
140</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]141
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]142<div class="doc_text">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]143
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]144<p>Some of the most noticable feature improvements this release have been in the
145optimizer, speeding it up and making it more aggressive. For example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]146
147<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]148
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]149<li>Daniel Berlin and Curtis Dunham rewrote Andersen's alias analysis (which is
150not enabled by default) to be several orders of magnitude faster, implemented
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]151Offline Variable Substitution and Lazy Cycle Detection.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]152
153Devang: LoopIndexSplit is enabled by default.
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]154
155Dan Gohman: LSR improvements for SSE intrinsics and
156
157Evan added simple exit value substitution to LSR.
158
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]159Anton added readnone/readonly attributes for modeling function side effects
160and Duncan hooked up GCC's pure/const attributes to use them and enhanced alias
161analysis to use them.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]162</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]163
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]164</div>
165
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]166<!--=========================================================================-->
167<div class="doc_subsection">
168<a name="codegen">Code Generator Improvements</a>
169</div>
170
171<div class="doc_text">
172
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]173<p>foci of this release was performance tuning and bug
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]174 fixing. In addition to these, several new major changes occurred:</p>
175
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]176<ul>
177
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]178<li>Owen contributed Machine Loop info, domintors, etc. Merged dom and
179 postdom.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]180
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]181<li>Dan added support for emitting debug information with .file and .loc on
182targets that support it</li>
183
184<li>Evan physical register dependencies in the BURR scheduler</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]185
186<li>Evan EXTRACT_SUBREG coalescing support</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]187<li>Evan enhanced LSR to support induction variable reuse when the induction
188 variables have different widths.</li>
189
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]190<li>Rafael Espindola byval support, finished by Evan for x86 (32/64).</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]191
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]192<li>mod/ref info for machineinstrs, inferred from .td files</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]193
194<li>Evan: Live interval splitting on MBB boundaries.</li>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]195
196Efficient iteration over use/defs of registers like llvm ir.
197
198The MachineInstr, MachineOperand and TargetInstrDesc classes are simpler, more
199consistent, and better documented.
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]200</ul>
201
202</div>
203
204
205<!--=========================================================================-->
206<div class="doc_subsection">
207<a name="targetspecific">Target Specific Improvements</a>
208</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]209
210<div class="doc_text">
211<p>New features include:
212</p>
213
214<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]215<li>Evan X86 now models EFLAGS in instructions.</li>
216<li>Evan: If conversion on by default for ARM.</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]217<li>Bruno: MIPS PIC support.</li>
218<li>Arnold Schwaighofer: X86 tail call support.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]219<li>Dale darwin/x86-64 and darwin/ppc eh</li>
220<li>Evan: darwin/x86 debug info</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]221</ul>
222
223</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]224
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]225
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]226<!--=========================================================================-->
227<div class="doc_subsection">
228<a name="llvmgccimprovements">llvm-gcc Improvements</a>
229</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]230
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]231<div class="doc_text">
232<p>New features include:
233</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]234
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]235<ul>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]236<li>.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]237</ul>
238
239</div>
240
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]241
242<!--=========================================================================-->
243<div class="doc_subsection">
244<a name="coreimprovements">LLVM Core Improvements</a>
245</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]246
247<div class="doc_text">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]248<p>New features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]249</p>
250
251<ul>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]252<li>Devang added LLVMFoldingBuilder.</li>
253<li>Dan added support for vector sin, cos, and pow intrinsics.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]254<li>Ted added a framework for generic object serialization to bitcode files,
255 only used by clang right now for ASTs but could be used for other
256 stuff.</li>
257<li>Duncan fixed TargetData to distinguish between the size/alignment of a type
258 in a register, in memory according to the platform ABI, and in memory when
259 we have a choice.</li>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]260<li>Duncan moved parameter attributes off of function type and onto functions
261 and calls, which makes it much easier to add attributes to a function in a
262 transformation.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]263</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]264
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]265</div>
266
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]267<!--=========================================================================-->
268<div class="doc_subsection">
269<a name="otherimprovements">Other Improvements</a>
270</div>
271
272<div class="doc_text">
273<p>New features include:
274</p>
275
276<ul>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]277<li>Gordon Henriksen updated docs/Passes.html</li>
278<li>New lexer and parser for tblgen, new lexer for asmparser</li>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame^]279<li>Dale GCC testsuite</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]280</ul>
281
282</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]283
284<!-- *********************************************************************** -->
285<div class="doc_section">
286 <a name="portability">Portability and Supported Platforms</a>
287</div>
288<!-- *********************************************************************** -->
289
290<div class="doc_text">
291
292<p>LLVM is known to work on the following platforms:</p>
293
294<ul>
295<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
296 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]297<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]298 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]299<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]300<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
301 support is available for native builds with Visual C++).</li>
302<li>Sun UltraSPARC workstations running Solaris 8.</li>
303<li>Alpha-based machines running Debian GNU/Linux.</li>
304<li>Itanium-based machines running Linux and HP-UX.</li>
305</ul>
306
307<p>The core LLVM infrastructure uses
308<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
309to the machine and operating system on which it is built. However, minor
310porting may be required to get LLVM to work on new platforms. We welcome your
311portability patches and reports of successful builds or error messages.</p>
312
313</div>
314
315<!-- *********************************************************************** -->
316<div class="doc_section">
317 <a name="knownproblems">Known Problems</a>
318</div>
319<!-- *********************************************************************** -->
320
321<div class="doc_text">
322
323<p>This section contains all known problems with the LLVM system, listed by
324component. As new problems are discovered, they will be added to these
325sections. If you run into a problem, please check the <a
326href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
327there isn't already one.</p>
328
329</div>
330
331<!-- ======================================================================= -->
332<div class="doc_subsection">
333 <a name="experimental">Experimental features included with this release</a>
334</div>
335
336<div class="doc_text">
337
338<p>The following components of this LLVM release are either untested, known to
339be broken or unreliable, or are in early development. These components should
340not be relied on, and bugs should not be filed against them, but they may be
341useful to some people. In particular, if you would like to work on one of these
342components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
343
344<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]345<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
346 LLVM 2.3.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]347<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
348<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
349 value for this option.</li>
350<li>The llvmc tool is not supported.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]351</ul>
352
353</div>
354
355<!-- ======================================================================= -->
356<div class="doc_subsection">
357 <a name="x86-be">Known problems with the X86 back-end</a>
358</div>
359
360<div class="doc_text">
361
362<ul>
363<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
364 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]365<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
366 problems</a> on operating systems that don't require 16-byte stack alignment
367 (including most non-darwin OS's like linux).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]368</ul>
369
370</div>
371
372<!-- ======================================================================= -->
373<div class="doc_subsection">
374 <a name="ppc-be">Known problems with the PowerPC back-end</a>
375</div>
376
377<div class="doc_text">
378
379<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]380<li>The Linux PPC32/ABI support needs testing for the interpreter and static
381compilation, and lacks support for debug information.</li>
382</ul>
383
384</div>
385
386<!-- ======================================================================= -->
387<div class="doc_subsection">
388 <a name="arm-be">Known problems with the ARM back-end</a>
389</div>
390
391<div class="doc_text">
392
393<ul>
394<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]395processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]396results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
397<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
398</li>
399<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
400programs compiled with LLVM. Please use more recent versions of QEMU.</li>
401</ul>
402
403</div>
404
405<!-- ======================================================================= -->
406<div class="doc_subsection">
407 <a name="sparc-be">Known problems with the SPARC back-end</a>
408</div>
409
410<div class="doc_text">
411
412<ul>
413<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
414 support the 64-bit SPARC ABI (-m64).</li>
415</ul>
416
417</div>
418
419<!-- ======================================================================= -->
420<div class="doc_subsection">
421 <a name="alpha-be">Known problems with the Alpha back-end</a>
422</div>
423
424<div class="doc_text">
425
426<ul>
427
428<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
429appropriate nops inserted to ensure restartability.</li>
430
431</ul>
432</div>
433
434<!-- ======================================================================= -->
435<div class="doc_subsection">
436 <a name="ia64-be">Known problems with the IA64 back-end</a>
437</div>
438
439<div class="doc_text">
440
441<ul>
442
443<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
444made where the argument is not 16-byte aligned, as required on IA64. (Strictly
445speaking this is not a bug in the IA64 back-end; it will also be encountered
446when building C++ programs using the C back-end.)</li>
447
448<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
449ABI compliant layout of v-tables</a>. In particular, it just stores function
450pointers instead of function descriptors in the vtable. This bug prevents
451mixing C++ code compiled with LLVM with C++ objects compiled by other C++
452compilers.</li>
453
454<li>There are a few ABI violations which will lead to problems when mixing LLVM
455output with code built with other compilers, particularly for floating-point
456programs.</li>
457
458<li>Defining vararg functions is not supported (but calling them is ok).</li>
459
460<li>The Itanium backend has bitrotted somewhat.</li>
461</ul>
462
463</div>
464
465<!-- ======================================================================= -->
466<div class="doc_subsection">
467 <a name="c-be">Known problems with the C back-end</a>
468</div>
469
470<div class="doc_text">
471
472<ul>
473<li><a href="http://llvm.org/PR802">The C backend does not support inline
474 assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]475<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
476 yet</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]477<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
478 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
479 C++ code compiled with LLC or native compilers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]480</ul>
481
482</div>
483
484
485<!-- ======================================================================= -->
486<div class="doc_subsection">
487 <a name="c-fe">Known problems with the C front-end</a>
488</div>
489
490<!-- _______________________________________________________________________ -->
491<div class="doc_subsubsection">Bugs</div>
492
493<div class="doc_text">
494
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]495<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
496Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]497llvmdev mailing list if you are interested.</p>
498
499</div>
500
501<!-- _______________________________________________________________________ -->
502<div class="doc_subsubsection">
503 Notes
504</div>
505
506<div class="doc_text">
507<ul>
508
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]509<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
510 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
511</li>
512
513<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
514 <ol>
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]515 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
516
517 As in Algol and Pascal, lexical scoping of functions.
518 Nested functions are supported, but llvm-gcc does not support
Duncan Sands6b761d32007-09-26 16:24:52 +0000[diff] [blame]519 taking the address of a nested function (except on the X86-32 target)
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]520 or non-local gotos.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]521
522 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
523
524 Declaring that functions have no side effects or that they can never
525 return.<br>
526
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]527 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
528 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]529 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]530 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
531 <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]532 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
533 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
534
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]535 <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
536 <tt>no_instrument_function</tt></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]537 </ol>
538</li>
539
540<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
541
542 <ol>
543 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
544 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
545 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
546 Other built-in functions.</li>
547 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
548 Specifying attributes of variables.</li>
549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
550 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
551 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
552 Arrays whose length is computed at run time.</li>
553 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
554 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
555 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
556 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
557 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
558 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
559 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
560 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
561 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
562 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
563 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
564 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
565 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
566 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
567 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
568 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
569 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
570 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
572 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
573 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
574 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
575or arrays as values.</li>
576 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
577 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
578 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
580 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
581 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
582 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
583 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character &lt;ESC&gt;.</li>
584 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
585 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
586 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
587 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
588 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
589 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
590 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
591 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
592 </ol></li>
593
594</ul>
595
596<p>If you run into GCC extensions which have not been included in any of these
597lists, please let us know (also including whether or not they work).</p>
598
599</div>
600
601<!-- ======================================================================= -->
602<div class="doc_subsection">
603 <a name="c++-fe">Known problems with the C++ front-end</a>
604</div>
605
606<div class="doc_text">
607
608<p>The C++ front-end is considered to be fully
609tested and works for a number of non-trivial programs, including LLVM
610itself, Qt, Mozilla, etc.</p>
611
612<ul>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]613<li>Exception handling only works well on the X86 and PowerPC targets.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]614</ul>
615
616</div>
617
618
619
620<!-- *********************************************************************** -->
621<div class="doc_section">
622 <a name="additionalinfo">Additional Information</a>
623</div>
624<!-- *********************************************************************** -->
625
626<div class="doc_text">
627
628<p>A wide variety of additional information is available on the <a
629href="http://llvm.org">LLVM web page</a>, in particular in the <a
630href="http://llvm.org/docs/">documentation</a> section. The web page also
631contains versions of the API documentation which is up-to-date with the
632Subversion version of the source code.
633You can access versions of these documents specific to this release by going
634into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
635
636<p>If you have any questions or comments about LLVM, please feel free to contact
637us via the <a href="http://llvm.org/docs/#maillist"> mailing
638lists</a>.</p>
639
640</div>
641
642<!-- *********************************************************************** -->
643
644<hr>
645<address>
646 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
647 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
648 <a href="http://validator.w3.org/check/referer"><img
649 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
650
651 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
652 Last modified: $Date$
653</address>
654
655</body>
656</html>