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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 2976f9e6d97630074aea8ad2beb434f443bfe5d1 / . / docs / ReleaseNotes.html
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Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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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 Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]71<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]72</div>
73
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]74<div class="doc_text">
75
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]76<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
77LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
78has made leaps and bounds and is now at least as good as 4.0 in virtually every
79area, and is better in several areas (for example, exception handling
80correctness). We strongly recommend that you migrate from llvm-gcc 4.0 to
81llvm-gcc 4.2 in this release cycle because <b>LLVM 2.2 is the last release
82that will support llvm-gcc 4.0</b>: LLVM 2.3 will only support the llvm-gcc
834.2 front-end.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]84
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]85<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
86a set of new 'llvm native' front-end technologies for the LLVM optimizer
87and code generator. Currently, its C and Objective-C support is maturing
88nicely, and it has advanced source-to-source analysis and transformation
89capabilities. If you are interested in building source-level tools for C and
90Objective-C (and eventually C++), you should take a look. However, note that
91clang is not an official part of the LLVM 2.2 release. If you are interested in
92this project, please see the web site.</p>
93
94</div>
95
96<!--=========================================================================-->
97<div class="doc_subsection">
98<a name="majorfeatures">Major New Features</a>
99</div>
100
101<div class="doc_text">
102
103<p>Dale contributed full support for long double on x86/x86-64 (where it is 80
104bits) and on Darwin PPC/PPC64 (where it is 128 bits).</p>
105
106<p>Ada, gfortran</p>
107
108<p>
109debug improvements -O0
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]110
111Gordon: GC Revamp. docs/GarbageCollection.html
112
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]113Kaleidoscope: docs/tutorial
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]114
115Gordon: C and Ocaml Bindings
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]116
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]117Christopher Lamb: Multiple address spaces.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]118</div>
119
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]120<!--=========================================================================-->
121<div class="doc_subsection">
122<a name="optimizer">Optimizer Improvements</a>
123</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]124
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]125<div class="doc_text">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]126
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]127<p>Some of the most noticable feature improvements this release have been in the
128optimizer, speeding it up and making it more aggressive. For example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]129
130<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]131
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]132<li>Daniel Berlin and Curtis Dunham rewrote Andersen's alias analysis (which is
133not enabled by default) to be several orders of magnitude faster, implemented
134Offline Variable Substitution.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]135
136Devang: LoopIndexSplit is enabled by default.
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]137
138Dan Gohman: LSR improvements for SSE intrinsics and
139
140Evan added simple exit value substitution to LSR.
141
142Anton added readnone/readonly attributes for modelling GCC pure/const
143attributes.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]144</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]145
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]146</div>
147
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]148<!--=========================================================================-->
149<div class="doc_subsection">
150<a name="codegen">Code Generator Improvements</a>
151</div>
152
153<div class="doc_text">
154
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]155<p>foci of this release was performance tuning and bug
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]156 fixing. In addition to these, several new major changes occurred:</p>
157
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]158<ul>
159
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]160<li>Owen contributed Machine Loop info, domintors, etc. Merged dom and
161 postdom.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]162
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]163<li>Dan added support for emitting debug information with .file and .loc on
164targets that support it</li>
165
166<li>Evan physical register dependencies in the BURR scheduler</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]167
168<li>Evan EXTRACT_SUBREG coalescing support</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]169<li>Evan enhanced LSR to support induction variable reuse when the induction
170 variables have different widths.</li>
171
172<li>Rafael Espindola byval support, finished by Evan.</li>
173
174<li>mod/ref info for machineinstrs</li>
175
176<li>Evan: Live interval splitting on MBB boundaries.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]177</ul>
178
179</div>
180
181
182<!--=========================================================================-->
183<div class="doc_subsection">
184<a name="targetspecific">Target Specific Improvements</a>
185</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]186
187<div class="doc_text">
188<p>New features include:
189</p>
190
191<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]192<li>Evan X86 now models EFLAGS in instructions.</li>
193<li>Evan: If conversion on by default for ARM.</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]194<li>Bruno: MIPS PIC support.</li>
195<li>Arnold Schwaighofer: X86 tail call support.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]196<li>Dale darwin/x86-64 and darwin/ppc eh</li>
197<li>Evan: darwin/x86 debug info</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]198</ul>
199
200</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]201
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]202
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]203<!--=========================================================================-->
204<div class="doc_subsection">
205<a name="llvmgccimprovements">llvm-gcc Improvements</a>
206</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]207
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]208<div class="doc_text">
209<p>New features include:
210</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]211
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]212<ul>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]213<li>.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]214</ul>
215
216</div>
217
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]218
219<!--=========================================================================-->
220<div class="doc_subsection">
221<a name="coreimprovements">LLVM Core Improvements</a>
222</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]223
224<div class="doc_text">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]225<p>New features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]226</p>
227
228<ul>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]229<li>Devang added LLVMFoldingBuilder.</li>
230<li>Dan added support for vector sin, cos, and pow intrinsics.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]231<li>Ted added a framework for generic object serialization to bitcode files,
232 only used by clang right now for ASTs but could be used for other
233 stuff.</li>
234<li>Duncan fixed TargetData to distinguish between the size/alignment of a type
235 in a register, in memory according to the platform ABI, and in memory when
236 we have a choice.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]237</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]238
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]239</div>
240
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]241<!--=========================================================================-->
242<div class="doc_subsection">
243<a name="otherimprovements">Other Improvements</a>
244</div>
245
246<div class="doc_text">
247<p>New features include:
248</p>
249
250<ul>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]251<li>Gordon Henriksen updated docs/Passes.html</li>
252<li>New lexer and parser for tblgen, new lexer for asmparser</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]253</ul>
254
255</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]256
257<!-- *********************************************************************** -->
258<div class="doc_section">
259 <a name="portability">Portability and Supported Platforms</a>
260</div>
261<!-- *********************************************************************** -->
262
263<div class="doc_text">
264
265<p>LLVM is known to work on the following platforms:</p>
266
267<ul>
268<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
269 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]270<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]271 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]272<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]273<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
274 support is available for native builds with Visual C++).</li>
275<li>Sun UltraSPARC workstations running Solaris 8.</li>
276<li>Alpha-based machines running Debian GNU/Linux.</li>
277<li>Itanium-based machines running Linux and HP-UX.</li>
278</ul>
279
280<p>The core LLVM infrastructure uses
281<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
282to the machine and operating system on which it is built. However, minor
283porting may be required to get LLVM to work on new platforms. We welcome your
284portability patches and reports of successful builds or error messages.</p>
285
286</div>
287
288<!-- *********************************************************************** -->
289<div class="doc_section">
290 <a name="knownproblems">Known Problems</a>
291</div>
292<!-- *********************************************************************** -->
293
294<div class="doc_text">
295
296<p>This section contains all known problems with the LLVM system, listed by
297component. As new problems are discovered, they will be added to these
298sections. If you run into a problem, please check the <a
299href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
300there isn't already one.</p>
301
302</div>
303
304<!-- ======================================================================= -->
305<div class="doc_subsection">
306 <a name="experimental">Experimental features included with this release</a>
307</div>
308
309<div class="doc_text">
310
311<p>The following components of this LLVM release are either untested, known to
312be broken or unreliable, or are in early development. These components should
313not be relied on, and bugs should not be filed against them, but they may be
314useful to some people. In particular, if you would like to work on one of these
315components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
316
317<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]318<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
319 LLVM 2.3.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]320<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
321<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
322 value for this option.</li>
323<li>The llvmc tool is not supported.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]324</ul>
325
326</div>
327
328<!-- ======================================================================= -->
329<div class="doc_subsection">
330 <a name="x86-be">Known problems with the X86 back-end</a>
331</div>
332
333<div class="doc_text">
334
335<ul>
336<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
337 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]338<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
339 problems</a> on operating systems that don't require 16-byte stack alignment
340 (including most non-darwin OS's like linux).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]341</ul>
342
343</div>
344
345<!-- ======================================================================= -->
346<div class="doc_subsection">
347 <a name="ppc-be">Known problems with the PowerPC back-end</a>
348</div>
349
350<div class="doc_text">
351
352<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]353<li>The Linux PPC32/ABI support needs testing for the interpreter and static
354compilation, and lacks support for debug information.</li>
355</ul>
356
357</div>
358
359<!-- ======================================================================= -->
360<div class="doc_subsection">
361 <a name="arm-be">Known problems with the ARM back-end</a>
362</div>
363
364<div class="doc_text">
365
366<ul>
367<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]368processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]369results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
370<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
371</li>
372<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
373programs compiled with LLVM. Please use more recent versions of QEMU.</li>
374</ul>
375
376</div>
377
378<!-- ======================================================================= -->
379<div class="doc_subsection">
380 <a name="sparc-be">Known problems with the SPARC back-end</a>
381</div>
382
383<div class="doc_text">
384
385<ul>
386<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
387 support the 64-bit SPARC ABI (-m64).</li>
388</ul>
389
390</div>
391
392<!-- ======================================================================= -->
393<div class="doc_subsection">
394 <a name="alpha-be">Known problems with the Alpha back-end</a>
395</div>
396
397<div class="doc_text">
398
399<ul>
400
401<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
402appropriate nops inserted to ensure restartability.</li>
403
404</ul>
405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="ia64-be">Known problems with the IA64 back-end</a>
410</div>
411
412<div class="doc_text">
413
414<ul>
415
416<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
417made where the argument is not 16-byte aligned, as required on IA64. (Strictly
418speaking this is not a bug in the IA64 back-end; it will also be encountered
419when building C++ programs using the C back-end.)</li>
420
421<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
422ABI compliant layout of v-tables</a>. In particular, it just stores function
423pointers instead of function descriptors in the vtable. This bug prevents
424mixing C++ code compiled with LLVM with C++ objects compiled by other C++
425compilers.</li>
426
427<li>There are a few ABI violations which will lead to problems when mixing LLVM
428output with code built with other compilers, particularly for floating-point
429programs.</li>
430
431<li>Defining vararg functions is not supported (but calling them is ok).</li>
432
433<li>The Itanium backend has bitrotted somewhat.</li>
434</ul>
435
436</div>
437
438<!-- ======================================================================= -->
439<div class="doc_subsection">
440 <a name="c-be">Known problems with the C back-end</a>
441</div>
442
443<div class="doc_text">
444
445<ul>
446<li><a href="http://llvm.org/PR802">The C backend does not support inline
447 assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]448<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
449 yet</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]450<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
451 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
452 C++ code compiled with LLC or native compilers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]453</ul>
454
455</div>
456
457
458<!-- ======================================================================= -->
459<div class="doc_subsection">
460 <a name="c-fe">Known problems with the C front-end</a>
461</div>
462
463<!-- _______________________________________________________________________ -->
464<div class="doc_subsubsection">Bugs</div>
465
466<div class="doc_text">
467
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]468<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
469Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]470llvmdev mailing list if you are interested.</p>
471
472</div>
473
474<!-- _______________________________________________________________________ -->
475<div class="doc_subsubsection">
476 Notes
477</div>
478
479<div class="doc_text">
480<ul>
481
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]482<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
483 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
484</li>
485
486<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
487 <ol>
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]488 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
489
490 As in Algol and Pascal, lexical scoping of functions.
491 Nested functions are supported, but llvm-gcc does not support
Duncan Sands6b761d32007-09-26 16:24:52 +0000[diff] [blame]492 taking the address of a nested function (except on the X86-32 target)
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]493 or non-local gotos.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]494
495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
496
497 Declaring that functions have no side effects or that they can never
498 return.<br>
499
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]500 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
501 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]502 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]503 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
504 <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]505 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
506 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
507
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]508 <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
509 <tt>no_instrument_function</tt></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]510 </ol>
511</li>
512
513<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
514
515 <ol>
516 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
517 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
518 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
519 Other built-in functions.</li>
520 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
521 Specifying attributes of variables.</li>
522 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
523 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
524 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
525 Arrays whose length is computed at run time.</li>
526 <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>
527 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
528 <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>
529 <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>
530 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
532 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
533 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
534 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
536 <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>
537 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
538 <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>
539 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
540 <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>
541 <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>
542 <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>
543 <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>
544 <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>
545 <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>
546 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
547 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
548or arrays as values.</li>
549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
550 <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>
551 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
552 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
553 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
554 <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>
555 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
556 <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>
557 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
558 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
559 <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>
560 <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>
561 <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>
562 <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>
563 <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>
564 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
565 </ol></li>
566
567</ul>
568
569<p>If you run into GCC extensions which have not been included in any of these
570lists, please let us know (also including whether or not they work).</p>
571
572</div>
573
574<!-- ======================================================================= -->
575<div class="doc_subsection">
576 <a name="c++-fe">Known problems with the C++ front-end</a>
577</div>
578
579<div class="doc_text">
580
581<p>The C++ front-end is considered to be fully
582tested and works for a number of non-trivial programs, including LLVM
583itself, Qt, Mozilla, etc.</p>
584
585<ul>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]586<li>Exception handling only works well on the X86 and PowerPC targets.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]587</ul>
588
589</div>
590
591
592
593<!-- *********************************************************************** -->
594<div class="doc_section">
595 <a name="additionalinfo">Additional Information</a>
596</div>
597<!-- *********************************************************************** -->
598
599<div class="doc_text">
600
601<p>A wide variety of additional information is available on the <a
602href="http://llvm.org">LLVM web page</a>, in particular in the <a
603href="http://llvm.org/docs/">documentation</a> section. The web page also
604contains versions of the API documentation which is up-to-date with the
605Subversion version of the source code.
606You can access versions of these documents specific to this release by going
607into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
608
609<p>If you have any questions or comments about LLVM, please feel free to contact
610us via the <a href="http://llvm.org/docs/#maillist"> mailing
611lists</a>.</p>
612
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