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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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4<head>
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]6 <link rel="stylesheet" href="llvm.css" type="text/css">
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]7 <title>LLVM 2.0 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 Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]11<div class="doc_title">LLVM 2.0 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 Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]35infrastructure, release 2.0. Here we describe the status of LLVM, including
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
47main LLVM web page,
Chris Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]48this document applies to the <i>next</i> release, not the current one. To see
49the release notes for the current or previous releases, see the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]50href="http://llvm.org/releases/">releases page</a>.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]51
52</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]53
54<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]55<div class="doc_section">
56 <a name="whatsnew">What's New?</a>
57</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]58<!-- *********************************************************************** -->
59
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]60<div class="doc_text">
61
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]62<p>This is the eleventh public release of the LLVM Compiler Infrastructure.
Chris Lattnerf01b0b52007-05-09 05:27:05 +0000[diff] [blame]63Being the first major release since 1.0, this release is different in several
64ways from our previous releases:</p>
65
66<ol>
67<li>We took this as an opportunity to
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]68break backwards compatibility with the LLVM 1.x bytecode and .ll file format.
69If you have LLVM 1.9 .ll files that you would like to upgrade to LLVM 2.x, we
Lauro Ramos Venanciobe1b1b12007-05-12 02:36:41 +0000[diff] [blame]70recommend the use of the stand alone <a href="#llvm-upgrade">llvm-upgrade</a>
Chris Lattnerbf8abe32007-05-17 19:58:57 +0000[diff] [blame]71tool (which is included with 2.0). We intend to keep compatibility with .ll
72and .bc formats within the 2.x release series, like we did within the 1.x
73series.</li>
Chris Lattnerf01b0b52007-05-09 05:27:05 +0000[diff] [blame]74<li>There are several significant change to the LLVM IR and internal APIs, such
75 as a major overhaul of the type system, the completely new bitcode file
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]76 format, etc (described below).</li>
Chris Lattnerf01b0b52007-05-09 05:27:05 +0000[diff] [blame]77<li>We designed the release around a 6 month release cycle instead of the usual
78 3-month cycle. This gave us extra time to develop and test some of the
79 more invasive features in this release.</li>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]80<li>LLVM 2.0 no longer supports the llvm-gcc3 front-end. Users are required to
81 upgrade to llvm-gcc4. llvm-gcc4 includes many features over
82 llvm-gcc3, is faster, and is <a href="CFEBuildInstrs.html">much easier to
83 build from source</a>.</li>
Chris Lattnerf01b0b52007-05-09 05:27:05 +0000[diff] [blame]84</ol>
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]85
Chris Lattnerf01b0b52007-05-09 05:27:05 +0000[diff] [blame]86<p>Note that while this is a major version bump, this release has been
87 extensively tested on a wide range of software. It is easy to say that this
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]88 is our best release yet, in terms of both features and correctness. This is
89 the first LLVM release to correctly compile and optimize major software like
90 LLVM itself, Mozilla/Seamonkey, Qt 4.3rc1, kOffice, etc out of the box on
91 linux/x86.
92 </p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]93
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]94</div>
95
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]96<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]97<div class="doc_subsection">
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]98<a name="newfeatures">New Features in LLVM 2.0</a>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]99</div>
100
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]101<!--_________________________________________________________________________-->
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]102<div class="doc_subsubsection"><a name="majorchanges">Major Changes</a></div>
103<div class="doc_text">
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]104
105<p>Changes to the LLVM IR itself:</p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]106
107<ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]108
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]109<li>Integer types are now completely signless. This means that we
110 have types like i8/i16/i32 instead of ubyte/sbyte/short/ushort/int
111 etc. LLVM operations that depend on sign have been split up into
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]112 separate instructions (<a href="http://llvm.org/PR950">PR950</a>). This
113 eliminates cast instructions that just change the sign of the operands (e.g.
114 int -> uint), which reduces the size of the IR and makes optimizers
115 simpler to write.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]116
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]117<li>Integer types with arbitrary bitwidths (e.g. i13, i36, i42, i1057, etc) are
118 now supported in the LLVM IR and optimizations (<a
119 href="http://llvm.org/PR1043">PR1043</a>). However, neither llvm-gcc
120 (<a href="http://llvm.org/PR1284">PR1284</a>) nor the native code generators
121 (<a href="http://llvm.org/PR1270">PR1270</a>) support non-standard width
122 integers yet.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]123
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]124<li>'Type planes' have been removed (<a href="http://llvm.org/PR411">PR411</a>).
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]125 It is no longer possible to have two values with the same name in the
126 same symbol table. This simplifies LLVM internals, allowing significant
127 speedups.</li>
128
129<li>Global variables and functions in .ll files are now prefixed with
130 @ instead of % (<a href="http://llvm.org/PR645">PR645</a>).</li>
131
132<li>The LLVM 1.x "bytecode" format has been replaced with a
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]133 completely new binary representation, named 'bitcode'. The <a
134 href="BitCodeFormat.html">Bitcode Format</a> brings a
135 number of advantages to the LLVM over the old bytecode format: it is denser
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]136 (files are smaller), more extensible, requires less memory to read,
137 is easier to keep backwards compatible (so LLVM 2.5 will read 2.0 .bc
138 files), and has many other nice features.</li>
139
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]140<li>Load and store instructions now track the alignment of their pointer
141 (<a href="http://www.llvm.org/PR400">PR400</a>). This allows the IR to
142 express loads that are not sufficiently aligned (e.g. due to '<tt>#pragma
143 packed</tt>') or to capture extra alignment information.</li>
144</ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]145
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]146<p>Major new features:</p>
147
148<ul>
149
150<li>A number of ELF features are now supported by LLVM, including 'visibility',
151 extern weak linkage, Thread Local Storage (TLS) with the <tt>__thread</tt>
152 keyword, and symbol aliases.
153 Among other things, this means that many of the special options needed to
154 configure llvm-gcc on linux are no longer needed, and special hacks to build
155 large C++ libraries like Qt are not needed.</li>
156
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]157<li>LLVM now has a new MSIL backend. <tt>llc -march=msil</tt> will now turn LLVM
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]158 into MSIL (".net") bytecode. This is still fairly early development
159 with a number of limitations.</li>
160
Chris Lattner46ccdbf2007-05-18 06:38:51 +0000[diff] [blame]161<li>A new <a href="CommandGuide/html/llvm-upgrade.html">llvm-upgrade</a> tool
162 exists to migrates LLVM 1.9 .ll files to LLVM 2.0 syntax.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]163</ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]164
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]165</div>
166
167
168<!--_________________________________________________________________________-->
169<div class="doc_subsubsection"><a name="llvmgccfeatures">llvm-gcc
170Improvements</a></div>
171<div class="doc_text">
172<p>New features include:
173</p>
174
175<ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]176<li>Precompiled Headers (PCH) are now supported.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]177
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]178<li>"<tt>#pragma packed</tt>" is now supported, as are the various features
179 described above (visibility, extern weak linkage, __thread, aliases,
180 etc).</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]181
182<li>Tracking function parameter/result attributes is now possible.</li>
183
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]184<li>Many internal enhancements have been added, such as improvements to
185 NON_LVALUE_EXPR, arrays with non-zero base, structs with variable sized
186 fields, VIEW_CONVERT_EXPR, CEIL_DIV_EXPR, nested functions, and many other
187 things. This is primarily to supports non-C GCC front-ends, like Ada.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]188
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]189<li>It is simpler to configure llvm-gcc for linux.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]190
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]191</ul>
192
193</div>
194
195<!--_________________________________________________________________________-->
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]196<div class="doc_subsubsection"><a name="optimizer">Optimizer
197Improvements</a></div>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]198
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]199<div class="doc_text">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]200<p>New features include:
201</p>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]202
203<ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]204<li>The <a href="WritingAnLLVMPass.html">pass manager</a> has been entirely
205 rewritten, making it significantly smaller, simpler, and more extensible.
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]206 Support has been added to run <tt>FunctionPass</tt>es interlaced with
207 <tt>CallGraphSCCPass</tt>es, we now support loop transformations
208 explicitly with <tt>LoopPass</tt>, and <tt>ModulePass</tt>es may now use the
209 result of <tt>FunctionPass</tt>es.</li>
210
211<li>LLVM 2.0 includes a new loop rotation pass, which converts "for loops" into
212 "do/while loops", where the condition is at the bottom of the loop.</li>
213
214<li>The Loop Strength Reduction pass has been improved, and we now support
215 sinking expressions across blocks to reduce register pressure.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]216
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]217<li>The <tt>-scalarrepl</tt> pass can now promote unions containing FP values
218 into a register, it can also handle unions of vectors of the same
219 size.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]220
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]221<li>The [Post]DominatorSet classes have been removed from LLVM and clients
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]222 switched to use the more-efficient ETForest class instead.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]223
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]224<li>The ImmediateDominator class has also been removed, and clients have been
225 switched to use DominatorTree instead.</li>
226
227<li>The predicate simplifier pass has been improved, making it able to do
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]228 simple value range propagation and eliminate more conditionals. However,
229 note that predsimplify is not enabled by default in llvm-gcc.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]230
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]231</ul>
232
Chris Lattner738bd302006-04-18 06:32:08 +0000[diff] [blame]233</div>
234
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]235<!--_________________________________________________________________________-->
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]236<div class="doc_subsubsection"><a name="codegen">Code
237Generator Enhancements</a></div>
238
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]239<div class="doc_text">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]240<p>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]241New features include:
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]242</p>
243
244<ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]245
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]246<li>LLVM now supports software floating point, which allows LLVM to target
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]247 chips that don't have hardware FPUs (e.g. ARM thumb mode).</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]248
249<li>A new register scavenger has been implemented, which is useful for
250 finding free registers after register allocation. This is useful when
251 rewriting frame references on RISC targets, for example.</li>
252
253<li>Heuristics have been added to avoid coalescing vregs with very large live
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]254 ranges to physregs. This was bad because it effectively pinned the physical
255 register for the entire lifetime of the virtual register (<a
256 href="http://llvm.org/PR711">PR711</a>).</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]257
258<li>Support now exists for very simple (but still very useful)
259 rematerialization the register allocator, enough to move
260 instructions like "load immediate" and constant pool loads.</li>
261
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]262<li>Switch statement lowering is significantly better, improving codegen for
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]263 sparse switches that have dense subregions, and implemented support
264 for the shift/and trick.</li>
265
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]266<li>LLVM now supports tracking physreg sub-registers and super-registers
267 in the code generator, and includes extensive register
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]268 allocator changes to track them.</li>
269
270<li>There is initial support for virtreg sub-registers
271 (<a href="http://llvm.org/PR1350">PR1350</a>).</li>
272
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]273</ul>
274
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]275<p>
276Other improvements include:
277</p>
278
279<ul>
280
281<li>Inline assembly support is much more solid that before.
282 The two primary features still missing are support for 80-bit floating point
283 stack registers on X86 (<a href="http://llvm.org/PR879">PR879</a>), and
284 support for inline asm in the C backend (<a
285 href="http://llvm.org/PR802">PR802</a>).</li>
286
287<li>DWARF debug information generation has been improved. LLVM now passes
288 most of the GDB testsuite on MacOS and debug info is more dense.</li>
289
290<li>Codegen support for Zero-cost DWARF exception handling has been added (<a
291 href="http://llvm.org/PR592">PR592</a>). It is mostly
292 complete and just in need of continued bug fixes and optimizations at
293 this point. However, support in llvm-g++ is disabled with an
294 #ifdef for the 2.0 release (<a
295 href="http://llvm.org/PR870">PR870</a>).</li>
296
297<li>The code generator now has more accurate and general hooks for
298 describing addressing modes ("isLegalAddressingMode") to
299 optimizations like loop strength reduction and code sinking.</li>
300
301<li>Progress has been made on a direct Mach-o .o file writer. Many small
302 apps work, but it is still not quite complete.</li>
303
304</ul>
305
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]306<p>In addition, the LLVM target description format has itself been extended in
307 several ways:</p>
308
309<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]310<li>TargetData now supports better target parameterization in
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]311 the .ll/.bc files, eliminating the 'pointersize/endianness' attributes
312 in the files (<a href="http://llvm.org/PR761">PR761</a>).</li>
313
314<li>TargetData was generalized for finer grained alignment handling,
315 handling of vector alignment, and handling of preferred alignment</li>
316
317<li>LLVM now supports describing target calling conventions
318 explicitly in .td files, reducing the amount of C++ code that needs
319 to be written for a port.</li>
320
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]321</ul>
322
Chris Lattner1c1a85c2006-04-19 04:02:47 +0000[diff] [blame]323</div>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]324
325<!--_________________________________________________________________________-->
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]326<div class="doc_subsubsection"><a name="specifictargets">Target-Specific
327Improvements</a></div>
328
329<div class="doc_text">
330
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]331<p>X86-specific Code Generator Enhancements:
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]332</p>
333
334<ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]335<li>The MMX instruction set is now supported through intrinsics.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]336<li>The scheduler was improved to better reduce register pressure on
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]337 X86 and other targets that are register pressure sensitive.</li>
338<li>Linux/x86-64 support is much better.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]339<li>PIC support for linux/x86 has been added.</li>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]340<li>The X86 backend now supports the GCC regparm attribute.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]341<li>LLVM now supports inline asm with multiple constraint letters per operand
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]342 (like "mri") which is common in X86 inline asms.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]343</ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]344
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]345<p>ARM-specific Code Generator Enhancements:</p>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]346
347<ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]348<li>The ARM code generator is now stable and fully supported.</li>
349
350<li>There are major new features, including support for ARM
351 v4-v6 chips, vfp support, soft float point support, pre/postinc support,
352 load/store multiple generation, constant pool entry motion (to support
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]353 large functions), inline asm support, weak linkage support, static
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]354 ctor/dtor support and many bug fixes.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]355
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]356<li>Added support for Thumb code generation (<tt>llc -march=thumb</tt>).</li>
357
358<li>The ARM backend now supports the ARM AAPCS/EABI ABI and PIC codegen on
359 arm/linux.</li>
360
361<li>Several bugs were fixed for DWARF debug info generation on arm/linux.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]362
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]363</ul>
364
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]365<p>PowerPC-specific Code Generator Enhancements:</p>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]366
367<ul>
368<li>The PowerPC 64 JIT now supports addressing code loaded above the 2G
369 boundary.</li>
370
371<li>Improved support for the Linux/ppc ABI and the linux/ppc JIT is fully
372 functional now. llvm-gcc and static compilation are not fully supported
Chris Lattnerbf8abe32007-05-17 19:58:57 +0000[diff] [blame]373 yet though.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]374
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]375<li>Many PowerPC 64 bug fixes.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]376
377</ul>
378
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]379</div>
380
381
382<!--_________________________________________________________________________-->
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000[diff] [blame]383<div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]384<div class="doc_text">
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]385
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000[diff] [blame]386<p>More specific changes include:</p>
387
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]388<ul>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]389<li>LLVM no longer relies on static destructors to shut itself down. Instead,
Chris Lattner46ccdbf2007-05-18 06:38:51 +0000[diff] [blame]390 it lazily initializes itself and shuts down when <tt>llvm_shutdown()</tt> is
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]391 explicitly called.</li>
392
393<li>LLVM now has significantly fewer static constructors, reducing startup time.
394 </li>
395
396<li>Several classes have been refactored to reduce the amount of code that
397 gets linked into apps that use the JIT.</li>
398
399<li>Construction of intrinsic function declarations has been simplified.</li>
400
Chris Lattner46ccdbf2007-05-18 06:38:51 +0000[diff] [blame]401<li>The gccas/gccld tools have been replaced with small shell scripts.</li>
Tanya Lattnerb6ec3a92007-05-16 23:25:46 +0000[diff] [blame]402
403<li>Support has been added to llvm-test for running on low-memory
404 or slow machines (make SMALL_PROBLEM_SIZE=1).</li>
405
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]406</ul>
407</div>
John Criswelle531ec52005-06-29 16:22:34 +0000[diff] [blame]408
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]409<!--_________________________________________________________________________-->
410<div class="doc_subsubsection"><a name="apichanges">API Changes</a></div>
411<div class="doc_text">
412
413<p>LLVM 2.0 contains a revamp of the type system and several other significant
414internal changes. If you are programming to the C++ API, be aware of the
415following major changes:</p>
416
417<ul>
Chris Lattner60893e52007-05-18 06:33:02 +0000[diff] [blame]418<li>Pass registration is slightly different in LLVM 2.0 (you now need an
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]419 <tt>intptr_t</tt> in your constructor), as explained in the <a
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]420 href="WritingAnLLVMPass.html#basiccode">Writing an LLVM Pass</a>
421 document.</li>
422
423<li><tt>ConstantBool</tt>, <tt>ConstantIntegral</tt> and <tt>ConstantInt</tt>
424 classes have been merged together, we now just have
425 <tt>ConstantInt</tt>.</li>
426
427<li><tt>Type::IntTy</tt>, <tt>Type::UIntTy</tt>, <tt>Type::SByteTy</tt>, ... are
428 replaced by <tt>Type::Int8Ty</tt>, <tt>Type::Int16Ty</tt>, etc. LLVM types
429 have always corresponded to fixed size types
430 (e.g. long was always 64-bits), but the type system no longer includes
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]431 information about the sign of the type. Also, the
432 <tt>Type::isPrimitiveType()</tt> method now returns false for integers.</li>
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]433
434<li>Several classes (<tt>CallInst</tt>, <tt>GetElementPtrInst</tt>,
435 <tt>ConstantArray</tt>, etc), that once took <tt>std::vector</tt> as
436 arguments now take ranges instead. For example, you can create a
437 <tt>GetElementPtrInst</tt> with code like:
438
439 <pre>
440 Value *Ops[] = { Op1, Op2, Op3 };
441 GEP = new GetElementPtrInst(BasePtr, Ops, 3);
442 </pre>
443
444 This avoids creation of a temporary vector (and a call to malloc/free). If
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]445 you have an <tt>std::vector</tt>, use code like this:
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]446 <pre>
447 std::vector&lt;Value*&gt; Ops = ...;
448 GEP = new GetElementPtrInst(BasePtr, &amp;Ops[0], Ops.size());
449 </pre>
450
451 </li>
452
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]453<li><tt>CastInst</tt> is now abstract and its functionality is split into
454 several parts, one for each of the <a href="LangRef.html#convertops">new
455 cast instructions</a>.</li>
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]456
457<li><tt>Instruction::getNext()/getPrev()</tt> are now private (along with
458 <tt>BasicBlock::getNext</tt>, etc), for efficiency reasons (they are now no
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]459 longer just simple pointers). Please use <tt>BasicBlock::iterator</tt>, etc
460 instead.
Chris Lattnerbfb17ab2007-05-17 21:41:31 +0000[diff] [blame]461</li>
462
463<li><tt>Module::getNamedFunction()</tt> is now called
464 <tt>Module::getFunction()</tt>.</li>
465
466<li><tt>SymbolTable.h</tt> has been split into <tt>ValueSymbolTable.h</tt> and
467<tt>TypeSymbolTable.h</tt>.</li>
468</ul>
469</div>
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]470
471
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]472<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]473<div class="doc_section">
474 <a name="portability">Portability and Supported Platforms</a>
475</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]476<!-- *********************************************************************** -->
477
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]478<div class="doc_text">
479
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]480<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]481
482<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]483<li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
Reid Spencer00812e22005-05-17 02:47:27 +0000[diff] [blame]484 (and probably other unix-like systems).</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]485<li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
486 64-bit modes.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]487<li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
488<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
489 support is available for native builds with Visual C++).</li>
490<li>Sun UltraSPARC workstations running Solaris 8.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]491<li>Alpha-based machines running Debian GNU/Linux.</li>
492<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]493</ul>
494
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]495<p>The core LLVM infrastructure uses
496<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
497to the machine and operating system on which it is built. However, minor
498porting may be required to get LLVM to work on new platforms. We welcome your
499portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]500
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]501</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]502
503<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]504<div class="doc_section">
505 <a name="knownproblems">Known Problems</a>
506</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]507<!-- *********************************************************************** -->
508
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]509<div class="doc_text">
510
511<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]512component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]513sections. If you run into a problem, please check the <a
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]514href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]515there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]516
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]517</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]518
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]519<!-- ======================================================================= -->
520<div class="doc_subsection">
521 <a name="experimental">Experimental features included with this release</a>
522</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]523
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]524<div class="doc_text">
525
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]526<p>The following components of this LLVM release are either untested, known to
527be broken or unreliable, or are in early development. These components should
528not be relied on, and bugs should not be filed against them, but they may be
529useful 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]530components, 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]531
532<ul>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]533<li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
534 future release.</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]535<li>C++ EH support is disabled for this release.</li>
536<li>The MSIL backend is experimental.</li>
Chris Lattner58504a62006-02-05 06:39:36 +0000[diff] [blame]537<li>The IA64 code generator is experimental.</li>
Chris Lattnerc463b272005-10-29 07:07:09 +0000[diff] [blame]538<li>The Alpha JIT is experimental.</li>
Chris Lattner44c933e2006-04-18 06:18:36 +0000[diff] [blame]539<li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
540 <tt>-filetype</tt> llc option.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]541</ul>
542
543</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]544
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]545<!-- ======================================================================= -->
546<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]547 <a name="x86-be">Known problems with the X86 back-end</a>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]548</div>
549
550<div class="doc_text">
551
552<ul>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]553<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]554 assembly that uses the X86 floating point stack</a>.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]555</ul>
556
557</div>
558
559<!-- ======================================================================= -->
560<div class="doc_subsection">
561 <a name="ppc-be">Known problems with the PowerPC back-end</a>
562</div>
563
564<div class="doc_text">
565
566<ul>
567<li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
568implement ordered FP comparisons</a>.</li>
Nicolas Geoffraye4285dc2007-05-15 09:21:28 +0000[diff] [blame]569<li>The Linux PPC32/ABI support needs testing for the interpreter and static
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]570compilation, and lacks support for debug information.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]571</ul>
572
573</div>
574
575<!-- ======================================================================= -->
576<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]577 <a name="arm-be">Known problems with the ARM back-end</a>
578</div>
579
580<div class="doc_text">
581
582<ul>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]583<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
584processors, thumb program can crash or produces wrong
585results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]586<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
587</li>
Chris Lattner57a460e2007-05-23 04:39:32 +0000[diff] [blame]588<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
589programs compiled with LLVM. Please use more recent versions of QEMU.</li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]590</ul>
591
592</div>
593
594<!-- ======================================================================= -->
595<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]596 <a name="sparc-be">Known problems with the SPARC back-end</a>
597</div>
598
599<div class="doc_text">
600
601<ul>
602<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
603 support the 64-bit SPARC ABI (-m64).</li>
604</ul>
605
606</div>
607
608<!-- ======================================================================= -->
609<div class="doc_subsection">
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]610 <a name="alpha-be">Known problems with the Alpha back-end</a>
611</div>
612
613<div class="doc_text">
614
615<ul>
616
617<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
618appropriate nops inserted to ensure restartability.</li>
619
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]620</ul>
621</div>
622
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]623<!-- ======================================================================= -->
624<div class="doc_subsection">
625 <a name="ia64-be">Known problems with the IA64 back-end</a>
626</div>
627
628<div class="doc_text">
629
630<ul>
631
632<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
633made where the argument is not 16-byte aligned, as required on IA64. (Strictly
634speaking this is not a bug in the IA64 back-end; it will also be encountered
635when building C++ programs using the C back-end.)</li>
636
637<li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
638ABI compliant layout of v-tables</a>. In particular, it just stores function
639pointers instead of function descriptors in the vtable. This bug prevents
640mixing C++ code compiled with LLVM with C++ objects compiled by other C++
641compilers.</li>
642
643<li>There are a few ABI violations which will lead to problems when mixing LLVM
644output with code built with other compilers, particularly for floating-point
645programs.</li>
646
647<li>Defining vararg functions is not supported (but calling them is ok).</li>
648
Chris Lattnercaf06342007-05-09 04:58:11 +0000[diff] [blame]649<li>The Itanium backend has bitrotted somewhat.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]650</ul>
651
652</div>
653
654<!-- ======================================================================= -->
655<div class="doc_subsection">
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]656 <a name="c-be">Known problems with the C back-end</a>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]657</div>
658
659<div class="doc_text">
660
661<ul>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]662<li><a href="http://llvm.org/PR802">The C backend does not support inline
663 assembly code</a>.</li>
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]664</ul>
665
666</div>
John Criswellc0c186d2005-11-08 21:11:33 +0000[diff] [blame]667
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]668
669<!-- ======================================================================= -->
670<div class="doc_subsection">
671 <a name="c-fe">Known problems with the C front-end</a>
672</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]673
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]674<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]675<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]676
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]677<div class="doc_text">
Chris Lattnerc5d658a2006-03-03 00:34:26 +0000[diff] [blame]678
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]679<p>llvm-gcc4 does not currently support <a href="http://llvm.org/PR869">Link-Time
680Optimization</a> on most platforms "out-of-the-box". Please inquire on the
681llvmdev mailing list if you are interested.</p>
Chris Lattnerd9ea0172006-08-08 17:27:28 +0000[diff] [blame]682
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]683</div>
684
685<!-- _______________________________________________________________________ -->
686<div class="doc_subsubsection">
687 Notes
688</div>
689
690<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]691<ul>
692
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]693<li><p>"long double" is silently transformed by the front-end into "double". There
694is no support for floating point data types of any size other than 32 and 64
695bits.</p></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]696
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]697<li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
698 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
699</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]700
Duncan Sands32a83442007-05-18 09:04:20 +0000[diff] [blame]701<li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]702 <ol>
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]703 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.<br>
704 Nested functions are supported, but llvm-gcc does not support non-local
705 gotos or taking the address of a nested function.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]706
707 <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]708
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]709 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]710 return.<br>
711
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]712 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
713 <tt>constructor</tt>, <tt>destructor</tt>,
Anton Korobeynikov9413de32006-11-18 08:04:48 +0000[diff] [blame]714 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
Anton Korobeynikov9ec81372007-05-10 08:26:24 +0000[diff] [blame]715 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noreturn</tt>, <tt>regparm</tt>
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]716 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
717 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]718
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]719 <b>Ignored:</b> <tt>noinline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
720 <tt>malloc</tt>, <tt>no_instrument_function</tt></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]721 </ol>
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]722</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]723
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]724<li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]725
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]726 <ol>
Chris Lattnerd09c4ec2007-05-17 22:02:24 +0000[diff] [blame]727 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
728 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
729 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
730 Other built-in functions.</li>
731 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
732 Specifying attributes of variables.</li>
733 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
734 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
735 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
736 Arrays whose length is computed at run time.</li>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]737 <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]738 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
739 <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]740 <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]741 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
742 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
743 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
744 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
745 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
746 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
747 <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>
748 <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]749 <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>
750 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
751 <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>
752 <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>
753 <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>
754 <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]755 <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]756 <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]757 <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]758 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
759or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]760 <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]761 <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]762 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
763 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
764 <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]765 <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]766 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
767 <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>
768 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
769 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
770 <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>
771 <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>
772 <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]773 <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]774 <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>
775 <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]776 </ol></li>
777
778</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]779
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]780<p>If you run into GCC extensions which have not been included in any of these
781lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]782
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]783</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]784
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]785<!-- ======================================================================= -->
786<div class="doc_subsection">
787 <a name="c++-fe">Known problems with the C++ front-end</a>
788</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]789
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]790<div class="doc_text">
791
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]792<p>The C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]793tested and works for a number of non-trivial programs, including LLVM
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]794itself, Qt, Mozilla, etc.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]795
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]796<ul>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]797<li>llvm-gcc4 only has partial support for <a href="http://llvm.org/PR870">C++
798Exception Handling</a>, and it is not enabled by default.</li>
799
800<!-- NO EH Support!
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]801
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]802<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]803 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]804 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]805 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]806 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]807
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]808<li>The LLVM C++ front-end follows the <a
809 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
810 This document, which is not Itanium specific, specifies a standard for name
811 mangling, class layout, v-table layout, RTTI formats, and other C++
812 representation issues. Because we use this API, code generated by the LLVM
813 compilers should be binary compatible with machine code generated by other
814 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
Chris Lattner26299222006-11-18 07:51:14 +0000[diff] [blame]815 <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]816 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]817 interact correctly</b>. </li>
Chris Lattnerf3e5bc62007-05-14 06:56:09 +0000[diff] [blame]818-->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]819</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]820
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]821</div>
822
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]823
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]824
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]825<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]826<div class="doc_section">
827 <a name="additionalinfo">Additional Information</a>
828</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]829<!-- *********************************************************************** -->
830
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]831<div class="doc_text">
832
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame]833<p>A wide variety of additional information is available on the <a
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]834href="http://llvm.org">LLVM web page</a>, in particular in the <a
835href="http://llvm.org/docs/">documentation</a> section. The web page also
Reid Spencer669ed452007-07-09 08:04:31 +0000[diff] [blame^]836contains versions of the API documentation which is up-to-date with the
837Subversion version of the source code.
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]838You can access versions of these documents specific to this release by going
839into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]840
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]841<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]842us via the <a href="http://llvm.org/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]843lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]844
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]845</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]846
847<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]848
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]849<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]850<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]851 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]852 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
853 <a href="http://validator.w3.org/check/referer"><img
854 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
855
Chris Lattnerb4b0ce72007-05-18 00:44:29 +0000[diff] [blame]856 <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]857 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]858</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]859
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]860</body>
861</html>