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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / be6fe28f75195cd0ebcf0846d1823266afd19023 / . / docs / ReleaseNotes.html
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Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]7 <title>LLVM 2.1 Release Notes</title>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]10
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]11<div class="doc_title">LLVM 2.1 Release Notes</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]12
13<ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
Chris Lattner4b538b92004-04-30 22:17:12 +0000[diff] [blame]16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]18 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]20</ol>
21
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]22<div class="doc_author">
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]24</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]25
26<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]27<div class="doc_section">
28 <a name="intro">Introduction</a>
29</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]30<!-- *********************************************************************** -->
31
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]32<div class="doc_text">
33
34<p>This document contains the release notes for the LLVM compiler
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]35infrastructure, release 2.1. Here we describe the status of LLVM, including
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]36major improvements from the previous release and any known problems. All LLVM
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]37releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]38releases web site</a>.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]39
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]40<p>For more information about LLVM, including information about the latest
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]41release, please check out the <a href="http://llvm.org/">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]42web site</a>. If you have questions or comments, the <a
43href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]44list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]45
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]46<p>Note that if you are reading this file from a Subversion checkout or the
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]47main LLVM web page, this document applies to the <i>next</i> release, not the
48current one. To see the release notes for a specific releases, please see the
49<a href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]50
51</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]52
53<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]54<div class="doc_section">
55 <a name="whatsnew">What's New?</a>
56</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]57<!-- *********************************************************************** -->
58
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]59<div class="doc_text">
60
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]61<p>This is the twelfth public release of the LLVM Compiler Infrastructure.
62It includes many features and refinements from LLVM 2.0.</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]63
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]64</div>
65
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]66<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]67<div class="doc_subsection">
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]68<a name="frontends">New Frontends</a>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]69</div>
70
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]71<div class="doc_text">
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]72
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]73<p>LLVM 2.1 brings two new beta C front-ends. First, a new version of llvm-gcc
74based on GCC 4.2, innovatively called "llvm-gcc-4.2". This promises to bring
75FORTRAN and Ada support to LLVM as well as features like atomic builtins and
76OpenMP. None of these actually work yet, but don't let that stop you checking
77it out!</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]78
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]79<p>Second, LLVM now includes its own native C and Objective-C front-end (C++ is
80in progress, but is not very far along) code named "<a
81href="http://clang.llvm.org/">clang</a>". This front-end has a number of great
82features, primarily aimed at source-level analysis and speeding up compile-time.
83At this point though, the LLVM Code Generator component is still very early in
84development, so it's mostly useful for people looking to build source-level
85analysis tools or source-to-source translators.</p>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]86
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]87</div>
88
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]89<!--=========================================================================-->
90<div class="doc_subsection">
91<a name="optimizer">Optimizer Improvements</a>
92</div>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]93
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]94<div class="doc_text">
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]95
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]96<p>Some of the most noticable feature improvements this release have been in the
97optimizer, speeding it up and making it more aggressive. For example:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]98
99<ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]100
Owen Anderson50fd0002007-09-25 02:10:58 +0000[diff] [blame]101<li>Owen Anderson wrote the new MemoryDependenceAnalysis pass, which provides
Chris Lattner6b588d92007-09-26 06:38:59 +0000[diff] [blame]102 a lazy, caching layer on top of <a
103 href="AliasAnalysis.html">AliasAnalysis</a>. He then used it to rewrite
Owen Anderson50fd0002007-09-25 02:10:58 +0000[diff] [blame]104 DeadStoreElimination which resulted in significantly better compile time in
105 common cases, </li>
106<li>Owen implemented the new GVN pass, which is also based on
107 MemoryDependenceAnalysis. This pass replaces GCSE/LoadVN in the standard
108 set of passes, providing more aggressive optimization at a some-what
109 improved compile-time cost.</li>
110<li>Owen implemented GVN-PRE, a partial redundancy elimination algorithm that
111 shares some details with the new GVN pass. It is still in need of compile
112 time tuning, and is not turned on by default.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]113<li>Devang merged ETForest and DomTree into a single easier to use data
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]114 structure. This makes it more obvious which datastructure to choose
115 (because there is only one) and makes the compiler more memory and time
116 efficient (less stuff to keep up-to-date).</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]117<li>Nick Lewycky improved loop trip count analysis to handle many more common
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]118 cases.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]119
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]120</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]121
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]122</div>
123
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]124<!--=========================================================================-->
125<div class="doc_subsection">
126<a name="codegen">Code Generator Improvements</a>
127</div>
128
129<div class="doc_text">
130
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]131<p>One of the main focuses of this release was performance tuning and bug
132 fixing. In addition to these, several new major changes occurred:</p>
133
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]134<ul>
135
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]136<li>Dale finished up the Tail Merging optimization in the code generator, and
137 enabled it by default. This produces smaller code that is also faster in
138 some cases.</li>
139
140<li>Christopher Lamb implemented support for virtual register sub-registers,
141 which can be used to better model many forms of subregisters. As an example
142 use, he modified the X86 backend to use this to model truncates and
143 extends more accurately (leading to better code).</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]144
145<li>Dan Gohman changed the way we represent vectors before legalization,
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]146 significantly simplifying the SelectionDAG representation for these and
147 making the code generator faster for vector code.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]148
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]149<li>Evan contributed a new target independent if-converter. While it is
Chris Lattnerb323ca82007-09-26 15:48:33 +0000[diff] [blame]150 target independent, so far only the ARM backend uses it.</li>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]151
Duncan Sands20acdce2007-09-27 08:24:02 +0000[diff] [blame]152<li>Evan rewrote the way the register allocator handles rematerialization,
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]153 allowing it to be much more effective on two-address targets like X86,
154 and taught it to fold loads away when possible (also a big win on X86).</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]155
156<li>Dan Gohman contributed support for better alignment and volatility handling
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]157 in the code generator, and significantly enhanced alignment analysis for SSE
158 load/store instructions. With his changes, an insufficiently-aligned SSE
159 load instruction turns into <tt>movups</tt>, for example.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]160
161<li>Duraid Madina contributed a new "bigblock" register allocator, and Roman
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]162 Levenstein contributed several big improvements. BigBlock is optimized for
163 code that uses very large basic blocks. It is slightly slower than the
164 "local" allocator, but produces much better code.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]165
Chris Lattner0d767892007-09-21 17:43:52 +0000[diff] [blame]166<li>David Greene refactored the register allocator to split coalescing out from
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]167 allocation, making coalescers pluggable.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]168
169</ul>
170
171</div>
172
173
174<!--=========================================================================-->
175<div class="doc_subsection">
176<a name="targetspecific">Target Specific Improvements</a>
177</div>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]178
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]179<div class="doc_text">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]180<p>New features include:
181</p>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]182
183<ul>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]184<li>Bruno Cardoso Lopes contributed initial MIPS support. It is sufficient to
185 run many small programs, but is still incomplete and is not yet
186 fully performant.</li>
187
Bill Wendling0678f602007-09-27 08:47:31 +0000[diff] [blame]188<li>Bill Wendling added SSSE3 support to the X86 backend.</li>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]189
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]190<li>Nicholas Geoffray contributed improved linux/ppc ABI and JIT support.</li>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]191
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]192<li>Dale Johannesen rewrote handling of 32-bit float values in the X86 backend
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]193 when using the floating point stack, fixing several nasty bugs.</li>
194
195<li>Dan contributed rematerialization support for the X86 backend, in addition
196 to several X86-specific micro optimizations.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]197</ul>
198
199</div>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]200
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]201
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]202<!--=========================================================================-->
203<div class="doc_subsection">
204<a name="llvmgccimprovements">llvm-gcc Improvements</a>
205</div>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]206
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]207<div class="doc_text">
208<p>New features include:
209</p>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]210
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]211<ul>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]212<li>Duncan and Anton made significant progress chasing down a number of problems
213 with C++ Zero-Cost exception handling in llvm-gcc 4.0 and 4.2. It is now at
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]214 the point where it "just works" on linux/X86-32 and has partial support on
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]215 other targets.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]216
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]217<li>Devang and Duncan fixed a huge number of bugs relating to bitfields, pragma
218 pack, and variable sized fields in structures.</li>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]219
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]220<li>Tanya implemented support for <tt>__attribute__((noinline))</tt> in
221 llvm-gcc, and added support for generic variable annotations which are
222 propagated into the LLVM IR, e.g.
223 "<tt>int X __attribute__((annotate("myproperty")));</tt>".</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]224
225<li>Sheng Zhou and Christopher Lamb implemented alias analysis support for
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]226"restrict" pointer arguments to functions.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]227
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]228<li>Duncan contributed support for trampolines (taking the address of a nested
Duncan Sands0869f4a2007-09-26 16:24:52 +0000[diff] [blame]229 function). Currently this is only supported on the X86-32 target.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]230
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]231<li>Lauro Ramos Venancio contributed support to encode alignment info in
232 load and store instructions, the foundation for other alignment-related
233 work.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]234</ul>
235
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]236</div>
237
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]238
239<!--=========================================================================-->
240<div class="doc_subsection">
241<a name="coreimprovements">LLVM Core Improvements</a>
242</div>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]243
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]244<div class="doc_text">
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]245<p>New features include:
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]246</p>
247
248<ul>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]249<li>Neil Booth contributed a new "APFloat" class, which ensures that floating
250 point representation and constant folding is not dependent on the host
251 architecture that builds the application. This support is the foundation
252 for "long double" support that will be wrapped up in LLVM 2.2.</li>
253
254<li>Based on the APFloat class, Dale redesigned the internals of the ConstantFP
255 class and has been working on extending the core and optimizer components to
256 support various target-specific 'long double's. We expect this work to be
257 completed in LLVM 2.2.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]258
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]259<li>LLVM now provides an LLVMBuilder class, which makes it significantly easier
260 to create LLVM IR instructions.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]261
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]262<li>Reid contributed support for intrinsics that take arbitrary integer typed
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]263 arguments. Dan Gohman and Chandler extended it to support arbitrary
264 floating point arguments and vectors.</li>
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]265</ul>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]266
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]267</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]268
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]269<!--=========================================================================-->
270<div class="doc_subsection">
271<a name="otherimprovements">Other Improvements</a>
272</div>
273
274<div class="doc_text">
275<p>New features include:
276</p>
277
278<ul>
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]279<li>Sterling Stein contributed a new BrainF frontend, located in llvm/examples.
280 This shows a some of the more modern APIs for building a front-end, and
281 demonstrates JIT compiler support.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]282
Chris Lattnerd4298712007-09-26 05:44:21 +0000[diff] [blame]283<li>David Green contributed a new <tt>--enable-expensive-checks</tt> configure
284 option which enables STL checking, and fixed several bugs exposed by
285 it.</li>
Chris Lattner84977642007-09-21 03:54:09 +0000[diff] [blame]286</ul>
287
288</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]289
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]290<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]291<div class="doc_section">
292 <a name="portability">Portability and Supported Platforms</a>
293</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]294<!-- *********************************************************************** -->
295
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]296<div class="doc_text">
297
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]298<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]299
300<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]301<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000[diff] [blame]302 (and probably other unix-like systems).</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]303<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
304 64-bit modes.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]305<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
306<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
307 support is available for native builds with Visual C++).</li>
308<li>Sun UltraSPARC workstations running Solaris 8.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]309<li>Alpha-based machines running Debian GNU/Linux.</li>
310<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]311</ul>
312
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]313<p>The core LLVM infrastructure uses
314<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
315to the machine and operating system on which it is built. However, minor
316porting may be required to get LLVM to work on new platforms. We welcome your
317portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]318
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]319</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]320
321<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]322<div class="doc_section">
323 <a name="knownproblems">Known Problems</a>
324</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]325<!-- *********************************************************************** -->
326
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]327<div class="doc_text">
328
329<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]330component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]331sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]332href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]333there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]334
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]335</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]336
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]337<!-- ======================================================================= -->
338<div class="doc_subsection">
339 <a name="experimental">Experimental features included with this release</a>
340</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]341
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]342<div class="doc_text">
343
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]344<p>The following components of this LLVM release are either untested, known to
345be broken or unreliable, or are in early development. These components should
346not be relied on, and bugs should not be filed against them, but they may be
347useful to some people. In particular, if you would like to work on one of these
Chris Lattner49e693e2006-08-09 04:08:52 +0000[diff] [blame]348components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]349
350<ul>
Bill Wendlingee143ad2007-09-25 20:45:10 +0000[diff] [blame]351<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in a
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]352 future release.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]353<li>The MSIL backend is experimental.</li>
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]354<li>The IA64 code generator is experimental.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]355<li>The Alpha backend is experimental.</li>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]356<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
357 <tt>-filetype</tt> llc option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]358</ul>
359
360</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]361
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]362<!-- ======================================================================= -->
363<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]364 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]365</div>
366
367<div class="doc_text">
368
369<ul>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]370<li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]371 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]372<li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
373 problems</a> on operating systems that don't require 16-byte stack alignment
374 (including most non-darwin OS's like linux).</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]375</ul>
376
377</div>
378
379<!-- ======================================================================= -->
380<div class="doc_subsection">
381 <a name="ppc-be">Known problems with the PowerPC back-end</a>
382</div>
383
384<div class="doc_text">
385
386<ul>
387<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
388implement ordered FP comparisons</a>.</li>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]389<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]390compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]391</ul>
392
393</div>
394
395<!-- ======================================================================= -->
396<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]397 <a name="arm-be">Known problems with the ARM back-end</a>
398</div>
399
400<div class="doc_text">
401
402<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]403<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]404processors, thumb programs can crash or produce wrong
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]405results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]406<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
407</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]408<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
409programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]410</ul>
411
412</div>
413
414<!-- ======================================================================= -->
415<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]416 <a name="sparc-be">Known problems with the SPARC back-end</a>
417</div>
418
419<div class="doc_text">
420
421<ul>
422<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
423 support the 64-bit SPARC ABI (-m64).</li>
424</ul>
425
426</div>
427
428<!-- ======================================================================= -->
429<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]430 <a name="alpha-be">Known problems with the Alpha back-end</a>
431</div>
432
433<div class="doc_text">
434
435<ul>
436
437<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
438appropriate nops inserted to ensure restartability.</li>
439
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]440</ul>
441</div>
442
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]443<!-- ======================================================================= -->
444<div class="doc_subsection">
445 <a name="ia64-be">Known problems with the IA64 back-end</a>
446</div>
447
448<div class="doc_text">
449
450<ul>
451
452<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
453made where the argument is not 16-byte aligned, as required on IA64. (Strictly
454speaking this is not a bug in the IA64 back-end; it will also be encountered
455when building C++ programs using the C back-end.)</li>
456
457<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
458ABI compliant layout of v-tables</a>. In particular, it just stores function
459pointers instead of function descriptors in the vtable. This bug prevents
460mixing C++ code compiled with LLVM with C++ objects compiled by other C++
461compilers.</li>
462
463<li>There are a few ABI violations which will lead to problems when mixing LLVM
464output with code built with other compilers, particularly for floating-point
465programs.</li>
466
467<li>Defining vararg functions is not supported (but calling them is ok).</li>
468
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]469<li>The Itanium backend has bitrotted somewhat.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]470</ul>
471
472</div>
473
474<!-- ======================================================================= -->
475<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]476 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]477</div>
478
479<div class="doc_text">
480
481<ul>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]482<li><a href="http://llvm.org/PR802">The C backend does not support inline
483 assembly code</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]484<li><a href="http://llvm.org/PR1126">The C backend does not support vectors
485 yet</a>.</li>
Chris Lattner725a0d82007-09-26 06:01:35 +0000[diff] [blame]486<li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
487 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
488 C++ code compiled with LLC or native compilers.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]489</ul>
490
491</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]492
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]493
494<!-- ======================================================================= -->
495<div class="doc_subsection">
496 <a name="c-fe">Known problems with the C front-end</a>
497</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]498
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]499<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]500<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]501
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]502<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]503
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]504<p>llvm-gcc4 does not currently support <a href="http://llvm.org/PR869">Link-Time
505Optimization</a> on most platforms "out-of-the-box". Please inquire on the
506llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000[diff] [blame]507
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]508</div>
509
510<!-- _______________________________________________________________________ -->
511<div class="doc_subsubsection">
512 Notes
513</div>
514
515<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]516<ul>
517
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]518<li><p>"long double" is silently transformed by the front-end into "double". There
519is no support for floating point data types of any size other than 32 and 64
520bits.</p></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]521
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]522<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
523 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
524</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]525
Duncan Sands32a83442007-05-18 09:04:20 +0000[diff] [blame]526<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]527 <ol>
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]528 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
529
530 As in Algol and Pascal, lexical scoping of functions.
531 Nested functions are supported, but llvm-gcc does not support
Duncan Sands0869f4a2007-09-26 16:24:52 +0000[diff] [blame]532 taking the address of a nested function (except on the X86-32 target)
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]533 or non-local gotos.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]534
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]536
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]537 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]538 return.<br>
539
Anton Korobeynikovbe6fe282007-11-16 11:12:01 +0000[diff] [blame^]540 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
541 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
Anton Korobeynikov9413de32006-11-18 08:04:48 +0000[diff] [blame]542 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikovbe6fe282007-11-16 11:12:01 +0000[diff] [blame^]543 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
544 <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]545 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
546 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]547
Anton Korobeynikovbe6fe282007-11-16 11:12:01 +0000[diff] [blame^]548 <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
549 <tt>no_instrument_function</tt></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]550 </ol>
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]551</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]552
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]553<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]554
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]555 <ol>
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]556 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
557 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
558 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
559 Other built-in functions.</li>
560 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
561 Specifying attributes of variables.</li>
562 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
563 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
564 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
565 Arrays whose length is computed at run time.</li>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]566 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]567 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
568 <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>
Tanya Lattnerca26c3e2004-06-22 03:48:17 +0000[diff] [blame]569 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]570 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
572 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
573 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
574 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
575 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
576 <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>
577 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]578 <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>
579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
580 <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>
581 <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>
582 <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>
583 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]584 <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>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]585 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]586 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]587 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
588or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]589 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]590 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]591 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
592 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
593 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
Tanya Lattner78537e42004-12-08 18:29:38 +0000[diff] [blame]594 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]595 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
596 <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>
597 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
598 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
599 <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>
600 <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>
601 <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>
Chris Lattner25795bc2004-02-14 04:08:29 +0000[diff] [blame]602 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]603 <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>
604 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]605 </ol></li>
606
607</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]608
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]609<p>If you run into GCC extensions which have not been included in any of these
610lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]611
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]612</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]613
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]614<!-- ======================================================================= -->
615<div class="doc_subsection">
616 <a name="c++-fe">Known problems with the C++ front-end</a>
617</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]618
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]619<div class="doc_text">
620
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]621<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]622tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]623itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]624
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]625<ul>
Duncan Sands0869f4a2007-09-26 16:24:52 +0000[diff] [blame]626<li>Exception handling only works well on the linux/X86-32 target.
Duncan Sandsc90d68b2007-09-26 15:59:54 +0000[diff] [blame]627In some cases, illegally throwing an exception does not result
628in a call to terminate.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]629
630<!-- NO EH Support!
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]631
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]632<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]633 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]634 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]635 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]636 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]637
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]638<li>The LLVM C++ front-end follows the <a
639 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
640 This document, which is not Itanium specific, specifies a standard for name
641 mangling, class layout, v-table layout, RTTI formats, and other C++
642 representation issues. Because we use this API, code generated by the LLVM
643 compilers should be binary compatible with machine code generated by other
644 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]645 <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]646 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]647 interact correctly</b>. </li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]648-->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]649</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]650
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]651</div>
652
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]653
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]654
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]655<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]656<div class="doc_section">
657 <a name="additionalinfo">Additional Information</a>
658</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]659<!-- *********************************************************************** -->
660
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]661<div class="doc_text">
662
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]663<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]664href="http://llvm.org">LLVM web page</a>, in particular in the <a
665href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame]666contains versions of the API documentation which is up-to-date with the
667Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]668You can access versions of these documents specific to this release by going
669into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]670
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]671<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]672us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]673lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]674
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]675</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]676
677<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]678
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]679<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]680<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]681 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]682 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
683 <a href="http://validator.w3.org/check/referer"><img
684 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
685
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]686 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]687 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]688</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]689
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]690</body>
691</html>