Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 8fda4951b12696884f060197137bee31f3959b38 / . / docs / ReleaseNotes.html
blob: ebc0fd7374ac79e551077681cf6f70816d95b893 [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
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]69<!-- Unfinished features in 2.2:
70 Index Set Splitting not enabled by default
71 Machine LICM
72 Machine Sinking
73 LegalizeDAGTypes
74 -->
75
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]76<!--=========================================================================-->
77<div class="doc_subsection">
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]78<a name="deprecation">Deprecated features in LLVM 2.2</a>
79</div>
80
81<div class="doc_text">
82
83<p>This is the last LLVM release to support llvm-gcc 4.0, llvm-upgrade, and
84llvmc in its current form. llvm-gcc 4.0 has been replaced with llvm-gcc 4.2.
85llvm-upgrade is useful for upgrading llvm 1.9 files to llvm 2.x syntax, but you
86can always use an old release to do this. llvmc is currently mostly useless in
87llvm 2.2, and will be redesigned or removed in llvm 2.3.</p>
88
89</div>
90
91<!--=========================================================================-->
92<div class="doc_subsection">
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]93<a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]94</div>
95
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]96<div class="doc_text">
97
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]98<p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
99LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
100has made leaps and bounds and is now at least as good as 4.0 in virtually every
101area, and is better in several areas (for example, exception handling
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]102correctness, support for Ada and FORTRAN). We strongly recommend that you
103migrate from llvm-gcc 4.0 to llvm-gcc 4.2 in this release cycle because
104<b>LLVM 2.2 is the last release that will support llvm-gcc 4.0</b>: LLVM 2.3
105will only support the llvm-gcc 4.2 front-end.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]106
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]107<p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
108a set of new 'llvm native' front-end technologies for the LLVM optimizer
109and code generator. Currently, its C and Objective-C support is maturing
110nicely, and it has advanced source-to-source analysis and transformation
111capabilities. If you are interested in building source-level tools for C and
112Objective-C (and eventually C++), you should take a look. However, note that
113clang is not an official part of the LLVM 2.2 release. If you are interested in
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]114this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]115
116</div>
117
118<!--=========================================================================-->
119<div class="doc_subsection">
120<a name="majorfeatures">Major New Features</a>
121</div>
122
123<div class="doc_text">
124
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]125<p>LLVM 2.2 includes several major new capabilities:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]126
127<ul>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]128<li>Scott Michel contributed an SPU backend, which generates code for the
129vector coprocessors on the Cell processor. (Status?)</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]130
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]131<li>llvm-gcc 4.2 has significantly improved support for the GCC Ada (GNAT) and
132FORTRAN (gfortran) frontends. Duncan has the llvm-gcc 4.2 GNAT front-end
133supporting almost all of the ACATS testsuite (except 2 tests?). The llvm-gcc
1344.2 gfortran front-end supports a broad range of FORTRAN code, but does <a
135href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]136
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]137<li>Dale contributed full support for long double on x86/x86-64 (where it is 80
138bits) and on Darwin PPC/PPC64 (where it is 128 bits). In previous LLVM
139releases, llvm-gcc silently mapped long double to double.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]140
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]141<li>Gordon rewrote most of the <a href="GarbageCollection.html">Accurate Garbage
142Collection</a> code in the code generator, making the generated code more
143efficient and adding support for the Ocaml garbage collector metadata
144format.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]145
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]146<li>LLVM now includes a new set of detailed <a
147href="tutorial/index.html">tutorials</a>, which explain how to implement a
148language with LLVM and shows how to use several important APIs.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]149
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]150</div>
151
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]152<!--=========================================================================-->
153<div class="doc_subsection">
154<a name="codegen">Code Generator Improvements</a>
155</div>
156
157<div class="doc_text">
158
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]159<p>We put a significant amount of work into the code generator infrastructure,
160which allows us to implement more aggressive algorithms and make it run
161faster:</p>
Chris Lattner7d2b1102007-09-26 05:44:21 +0000[diff] [blame]162
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]163<ul>
164
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]165<li>Owen refactored the existing LLVM dominator and loop information code to
166allow it work on the machine code representation. He contributed support for
167dominator and loop information on machine code and merged the code for forward
168and backward dominator computation.</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]169
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]170<li>Dan added support for emitting debug information with .file and .loc
171directives on that support it, instead of emitting large tables in the .s
172file.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]173
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]174<li>Evan extended the DAG scheduler to model physical register dependencies
175explicitly and have the BURR scheduler pick a correct schedule based on the
176dependencies. This reduces our use of the 'flag' operand hack.</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]177
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]178<li>Evan added initial support for register coalescing of subregister
179references.</li>
180
181<li>Rafael Espindola implemented initial support for a new 'byval' attribute,
182which allows more efficient by-value argument passing in the LLVM IR. Evan
183finished support for it and enabled it in the X86 (32- and 64-bit) and C
184backends.</li>
185
186<li>The LLVM TargetInstrInfo class can now answer queries about the mod/ref and
187side-effect behavior of MachineInstr's. This information is inferred
188automatically by TableGen from .td files for all instructions with
189patterns.</li>
190
191<li>Evan implemented simple live interval splitting on basic block boundaries.
192This allows the register allocator to be more successful at keeping values in
193registers in some parts of a value's live range, even if they need to be spilled
194in some other block.</li>
195
196<li>The new MachineRegisterInfo.h class provides support for efficiently
197iterating over all defs/uses of a register, and this information is
198automatically kept up-to-date. This support is similar to the use_iterator in
199the LLVM IR level.</li>
200
201<li>The MachineInstr, MachineOperand and TargetInstrDesc classes are simpler,
202more consistent, and better documented.</li>
203</ul>
204
205</div>
206
207<!--=========================================================================-->
208<div class="doc_subsection">
209<a name="optimizer">Optimizer Improvements</a>
210</div>
211
212<div class="doc_text">
213
214<p>In addition to a huge array of bug fixes and minor performance tweaks, LLVM
2152.2 supports a few major enhancements:</p>
216
217<ul>
218
219<li>Daniel Berlin and Curtis Dunham rewrote Andersen's alias analysis to be
220several orders of magnitude faster, implemented Offline Variable Substitution
221and Lazy Cycle Detection. Note that Andersen's is not enabled in llvm-gcc by
222default.</li>
223
224<li>Dan Gohman contributed several enhancements to Loop Strength Reduction (LSR)
225to make it more aggressive with SSE intrinsics.</li>
226
227<li>Evan added support for simple exit value substitution to LSR.</li>
228
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]229<li>Evan enhanced LSR to support induction variable reuse when the induction
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]230variables have different widths.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]231
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]232</ul>
233
234</div>
235
236
237<!--=========================================================================-->
238<div class="doc_subsection">
239<a name="targetspecific">Target Specific Improvements</a>
240</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]241
242<div class="doc_text">
243<p>New features include:
244</p>
245
246<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]247<li>Evan X86 now models EFLAGS in instructions.</li>
248<li>Evan: If conversion on by default for ARM.</li>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]249<li>Bruno: MIPS PIC support.</li>
250<li>Arnold Schwaighofer: X86 tail call support.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]251<li>Dale darwin/x86-64 and darwin/ppc eh</li>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]252<li>Evan: darwin/x86 debug info, improvements at -O0?</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
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]257<!--=========================================================================-->
258<div class="doc_subsection">
259<a name="coreimprovements">LLVM Core Improvements</a>
260</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]261
262<div class="doc_text">
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]263<p>New features include:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]264</p>
265
266<ul>
Chris Lattner358c3272008-02-06 18:32:06 +0000[diff] [blame]267<li>Devang added LLVMFoldingBuilder.</li>
268<li>Dan added support for vector sin, cos, and pow intrinsics.</li>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]269<li>Ted added a framework for generic object serialization to bitcode files,
270 only used by clang right now for ASTs but could be used for other
271 stuff.</li>
272<li>Duncan fixed TargetData to distinguish between the size/alignment of a type
273 in a register, in memory according to the platform ABI, and in memory when
274 we have a choice.</li>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]275<li>Duncan moved parameter attributes off of function type and onto functions
276 and calls, which makes it much easier to add attributes to a function in a
277 transformation.</li>
Chris Lattner8fda4952008-02-10 07:46:44 +0000[diff] [blame^]278<li>Christopher Lamb: Multiple address spaces.</li>
279<li>Gordon: C and Ocaml Bindings</li>
280
281<li>Anton added readnone/readonly attributes for modeling function side effects
282and Duncan hooked up GCC's pure/const attributes to use them and enhanced alias
283analysis to use them.</li>
284
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]285</ul>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]286
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]287</div>
288
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]289<!--=========================================================================-->
290<div class="doc_subsection">
291<a name="otherimprovements">Other Improvements</a>
292</div>
293
294<div class="doc_text">
295<p>New features include:
296</p>
297
298<ul>
Chris Lattner527afe62008-02-09 22:58:07 +0000[diff] [blame]299<li>Gordon Henriksen updated docs/Passes.html</li>
300<li>New lexer and parser for tblgen, new lexer for asmparser</li>
Chris Lattner41bf8e92008-02-10 07:04:35 +0000[diff] [blame]301<li>Dale GCC testsuite</li>
Chris Lattnerb0d6c502007-09-21 03:54:09 +0000[diff] [blame]302</ul>
303
304</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]305
306<!-- *********************************************************************** -->
307<div class="doc_section">
308 <a name="portability">Portability and Supported Platforms</a>
309</div>
310<!-- *********************************************************************** -->
311
312<div class="doc_text">
313
314<p>LLVM is known to work on the following platforms:</p>
315
316<ul>
317<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
318 (and probably other unix-like systems).</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]319<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]320 64-bit modes.</li>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]321<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]322<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
323 support is available for native builds with Visual C++).</li>
324<li>Sun UltraSPARC workstations running Solaris 8.</li>
325<li>Alpha-based machines running Debian GNU/Linux.</li>
326<li>Itanium-based machines running Linux and HP-UX.</li>
327</ul>
328
329<p>The core LLVM infrastructure uses
330<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
331to the machine and operating system on which it is built. However, minor
332porting may be required to get LLVM to work on new platforms. We welcome your
333portability patches and reports of successful builds or error messages.</p>
334
335</div>
336
337<!-- *********************************************************************** -->
338<div class="doc_section">
339 <a name="knownproblems">Known Problems</a>
340</div>
341<!-- *********************************************************************** -->
342
343<div class="doc_text">
344
345<p>This section contains all known problems with the LLVM system, listed by
346component. As new problems are discovered, they will be added to these
347sections. If you run into a problem, please check the <a
348href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
349there isn't already one.</p>
350
351</div>
352
353<!-- ======================================================================= -->
354<div class="doc_subsection">
355 <a name="experimental">Experimental features included with this release</a>
356</div>
357
358<div class="doc_text">
359
360<p>The following components of this LLVM release are either untested, known to
361be broken or unreliable, or are in early development. These components should
362not be relied on, and bugs should not be filed against them, but they may be
363useful to some people. In particular, if you would like to work on one of these
364components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
365
366<ul>
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]367<li>The <tt>-cee</tt> pass is known to be buggy and will be removed in
368 LLVM 2.3.</li>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]369<li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
370<li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
371 value for this option.</li>
372<li>The llvmc tool is not supported.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]373</ul>
374
375</div>
376
377<!-- ======================================================================= -->
378<div class="doc_subsection">
379 <a name="x86-be">Known problems with the X86 back-end</a>
380</div>
381
382<div class="doc_text">
383
384<ul>
385<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
386 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]387<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
388 problems</a> on operating systems that don't require 16-byte stack alignment
389 (including most non-darwin OS's like linux).</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]390</ul>
391
392</div>
393
394<!-- ======================================================================= -->
395<div class="doc_subsection">
396 <a name="ppc-be">Known problems with the PowerPC back-end</a>
397</div>
398
399<div class="doc_text">
400
401<ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]402<li>The Linux PPC32/ABI support needs testing for the interpreter and static
403compilation, and lacks support for debug information.</li>
404</ul>
405
406</div>
407
408<!-- ======================================================================= -->
409<div class="doc_subsection">
410 <a name="arm-be">Known problems with the ARM back-end</a>
411</div>
412
413<div class="doc_text">
414
415<ul>
416<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]417processors, thumb programs can crash or produce wrong
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]418results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
419<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
420</li>
421<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
422programs compiled with LLVM. Please use more recent versions of QEMU.</li>
423</ul>
424
425</div>
426
427<!-- ======================================================================= -->
428<div class="doc_subsection">
429 <a name="sparc-be">Known problems with the SPARC back-end</a>
430</div>
431
432<div class="doc_text">
433
434<ul>
435<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
436 support the 64-bit SPARC ABI (-m64).</li>
437</ul>
438
439</div>
440
441<!-- ======================================================================= -->
442<div class="doc_subsection">
443 <a name="alpha-be">Known problems with the Alpha back-end</a>
444</div>
445
446<div class="doc_text">
447
448<ul>
449
450<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
451appropriate nops inserted to ensure restartability.</li>
452
453</ul>
454</div>
455
456<!-- ======================================================================= -->
457<div class="doc_subsection">
458 <a name="ia64-be">Known problems with the IA64 back-end</a>
459</div>
460
461<div class="doc_text">
462
463<ul>
464
465<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
466made where the argument is not 16-byte aligned, as required on IA64. (Strictly
467speaking this is not a bug in the IA64 back-end; it will also be encountered
468when building C++ programs using the C back-end.)</li>
469
470<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
471ABI compliant layout of v-tables</a>. In particular, it just stores function
472pointers instead of function descriptors in the vtable. This bug prevents
473mixing C++ code compiled with LLVM with C++ objects compiled by other C++
474compilers.</li>
475
476<li>There are a few ABI violations which will lead to problems when mixing LLVM
477output with code built with other compilers, particularly for floating-point
478programs.</li>
479
480<li>Defining vararg functions is not supported (but calling them is ok).</li>
481
482<li>The Itanium backend has bitrotted somewhat.</li>
483</ul>
484
485</div>
486
487<!-- ======================================================================= -->
488<div class="doc_subsection">
489 <a name="c-be">Known problems with the C back-end</a>
490</div>
491
492<div class="doc_text">
493
494<ul>
495<li><a href="http://llvm.org/PR802">The C backend does not support inline
496 assembly code</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]497<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
498 yet</a>.</li>
Chris Lattnere0194462007-09-26 06:01:35 +0000[diff] [blame]499<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
500 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
501 C++ code compiled with LLC or native compilers.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]502</ul>
503
504</div>
505
506
507<!-- ======================================================================= -->
508<div class="doc_subsection">
509 <a name="c-fe">Known problems with the C front-end</a>
510</div>
511
512<!-- _______________________________________________________________________ -->
513<div class="doc_subsubsection">Bugs</div>
514
515<div class="doc_text">
516
Chris Lattnere0798082008-02-06 18:00:06 +0000[diff] [blame]517<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
518Optimization</a> on most platforms "out-of-the-box". Please inquire on the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]519llvmdev mailing list if you are interested.</p>
520
521</div>
522
523<!-- _______________________________________________________________________ -->
524<div class="doc_subsubsection">
525 Notes
526</div>
527
528<div class="doc_text">
529<ul>
530
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]531<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
532 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
533</li>
534
535<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
536 <ol>
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]537 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
538
539 As in Algol and Pascal, lexical scoping of functions.
540 Nested functions are supported, but llvm-gcc does not support
Duncan Sands6b761d32007-09-26 16:24:52 +0000[diff] [blame]541 taking the address of a nested function (except on the X86-32 target)
Duncan Sands1827fa62007-09-26 15:59:54 +0000[diff] [blame]542 or non-local gotos.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]543
544 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
545
546 Declaring that functions have no side effects or that they can never
547 return.<br>
548
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]549 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
550 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]551 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]552 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
553 <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]554 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
555 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
556
Anton Korobeynikov08dcc472007-11-16 11:12:01 +0000[diff] [blame]557 <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
558 <tt>no_instrument_function</tt></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]559 </ol>
560</li>
561
562<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
563
564 <ol>
565 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
566 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
567 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
568 Other built-in functions.</li>
569 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
570 Specifying attributes of variables.</li>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
572 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
573 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
574 Arrays whose length is computed at run time.</li>
575 <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>
576 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
577 <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>
578 <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>
579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
580 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
581 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
582 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
583 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
584 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
585 <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>
586 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
587 <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>
588 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
589 <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>
590 <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>
591 <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>
592 <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>
593 <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>
594 <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>
595 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
596 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
597or arrays as values.</li>
598 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
599 <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>
600 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
601 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
602 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
603 <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>
604 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
605 <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>
606 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
607 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
608 <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>
609 <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>
610 <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>
611 <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>
612 <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>
613 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
614 </ol></li>
615
616</ul>
617
618<p>If you run into GCC extensions which have not been included in any of these
619lists, please let us know (also including whether or not they work).</p>
620
621</div>
622
623<!-- ======================================================================= -->
624<div class="doc_subsection">
625 <a name="c++-fe">Known problems with the C++ front-end</a>
626</div>
627
628<div class="doc_text">
629
630<p>The C++ front-end is considered to be fully
631tested and works for a number of non-trivial programs, including LLVM
632itself, Qt, Mozilla, etc.</p>
633
634<ul>
Chris Lattnerbd633de92008-02-06 06:30:34 +0000[diff] [blame]635<li>Exception handling only works well on the X86 and PowerPC targets.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]636</ul>
637
638</div>
639
640
641
642<!-- *********************************************************************** -->
643<div class="doc_section">
644 <a name="additionalinfo">Additional Information</a>
645</div>
646<!-- *********************************************************************** -->
647
648<div class="doc_text">
649
650<p>A wide variety of additional information is available on the <a
651href="http://llvm.org">LLVM web page</a>, in particular in the <a
652href="http://llvm.org/docs/">documentation</a> section. The web page also
653contains versions of the API documentation which is up-to-date with the
654Subversion version of the source code.
655You can access versions of these documents specific to this release by going
656into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
657
658<p>If you have any questions or comments about LLVM, please feel free to contact
659us via the <a href="http://llvm.org/docs/#maillist"> mailing
660lists</a>.</p>
661
662</div>
663
664<!-- *********************************************************************** -->
665
666<hr>
667<address>
668 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
669 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
670 <a href="http://validator.w3.org/check/referer"><img
671 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
672
673 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
674 Last modified: $Date$
675</address>
676
677</body>
678</html>