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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 416db10a5bd74d0dd1325eb5d475648b0ff6c588 / . / docs / ReleaseNotes.html
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4<head>
Reid Spencer6454ed32004-11-18 18:38:58 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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Chris Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]7 <title>LLVM 1.5 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 Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]11<div class="doc_title">LLVM 1.5 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 Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]23 <p>Written by the <a href="http://llvm.cs.uiuc.edu">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 Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]35infrastructure, release 1.5. Here we describe the status of LLVM, including any
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]36known problems and major improvements from the previous release. The most
37up-to-date version of this document can be found on the <a
Chris Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]38href="http://llvm.cs.uiuc.edu/releases/1.5/">LLVM 1.5 web site</a>. If you are
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]39not reading this on the LLVM web pages, you should probably go there because
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]40this document may be updated after the release.</p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]41
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]42<p>For more information about LLVM, including information about the latest
43release, please check out the <a href="http://llvm.cs.uiuc.edu">main LLVM
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]44web site</a>. If you have questions or comments, the <a
45href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]46list</a> is a good place to send them.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]47
Chris Lattner78bf32b2004-12-09 22:22:58 +0000[diff] [blame]48<p>Note that if you are reading this file from CVS or the main LLVM web page,
49this document applies to the <i>next</i> release, not the current one. To see
50the release notes for the current or previous releases, see the <a
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]51href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
52
53</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]54
55<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]56<div class="doc_section">
57 <a name="whatsnew">What's New?</a>
58</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]59<!-- *********************************************************************** -->
60
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]61<div class="doc_text">
62
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]63<p>This is the sixth public release of the LLVM Compiler Infrastructure.</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]64
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]65<p>LLVM 1.5 is known to correctly compile a wide range of C and C++ programs,
66includes bug fixes for those problems found since the 1.4 release, and includes
67a large number of new features and enhancements, described below.</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]68
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]69</div>
70
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]71<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]72<div class="doc_subsection">
73<a name="newfeatures">New Features in LLVM 1.5</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]74</div>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]75
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]76<!--_________________________________________________________________________-->
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]77<div class="doc_subsubsection"><a name="newcg">New Native Code
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]78Generators</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]79
80<div class="doc_text">
81<p>
82This release includes new native code generators for <a
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]83href="#alpha-be">Alpha</a>, <a href="#ia64-be">IA-64</a>, and <a
84href="#sparcv8">SPARC-V8</a> (32-bit SPARC). These code generators are still
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]85beta quality, but are progressing rapidly. The Alpha backend is implemented
86with an eye towards being compatible with the widely used SimpleScalar
87simulator.
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]88</p>
89</div>
90
91<!--_________________________________________________________________________-->
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]92<div class="doc_subsubsection"><a name="selectiondag">New Instruction
93Selector Framework</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]94
95<div class="doc_text">
96<p>This release includes a <a href="CodeGenerator.html#instselect">new framework
97for building instruction selectors</a>, which has long been the hardest part of
98building a new LLVM target. This framework handles a lot of the mundane (but
99easy to get wrong) details of writing the instruction selector, such as
100generating efficient code for <a
101href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting
102small integer types to larger types (e.g. for RISC targets with one size of
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]103integer registers), expanding 64-bit integer operations for 32-bit targets, etc.
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]104Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The
105SPARC backends will be migrated when time permits.
106</p>
107</div>
108
109<!--_________________________________________________________________________-->
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]110<div class="doc_subsubsection"><a name="customccs">New Support for Per-Function
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]111Calling Conventions</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]112
113<div class="doc_text">
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]114<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">per-function
115calling conventions</a>. Traditionally, the LLVM code generators match the
116native C calling conventions for a target. This is important for compatibility,
117but is not very flexible. This release allows custom calling conventions to be
118established for functions, and defines three target-independent conventions (<a
119href="LangRef.html#callingconv">C call, fast call, and cold call</a>) which may
120be supported by code generators. When possible, the LLVM optimizer promotes C
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]121functions to use the "fastcc" convention, allowing the use of more efficient
122calling sequences (e.g., parameters are passed in registers in the X86 target).
123</p>
124
125<p>Targets may now also define target-specific calling conventions, allowing
126LLVM to fully support calling convention altering options (e.g. GCC's
127<tt>-mregparm</tt> flag) and well-defined target conventions (e.g. stdcall and
128fastcall on X86).</p>
129</div>
130
131<!--_________________________________________________________________________-->
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]132<div class="doc_subsubsection"><a name="tailcalls">New Support for
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]133Proper Tail Calls</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]134
135<div class="doc_text">
136<p>The release now includes support for <a
137href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as
138required to implement languages like Scheme. Tail calls make use of two
139features: custom calling conventions (described above), which allow the code
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]140generator to use a convention where the caller deallocates its stack before it
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]141returns. The second feature is a flag on the <a href="LangRef.html#i_call">call
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]142instruction</a>, which indicates that the callee does not access the caller's
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]143stack frame (indicating that it is acceptable to deallocate the caller stack
144before invoking the callee). LLVM proper tail calls run on the system stack (as
145do normal calls), supports indirect tail calls, tail calls with arbitrary
146numbers of arguments, tail calls where the callee requires more argument space
147than the caller, etc. The only case not supported are varargs calls, but that
148could be added if desired.
149</p>
150
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]151<p>In order for a front-end to get a guaranteed tail call, it must mark
152functions as "fastcc", mark calls with the 'tail' marker, and follow the call
153with a return of the called value (or void). The optimizer and code generator
154attempt to handle more general cases, but the simple case will always work if
155the code generator supports tail calls. Here is an example:</p>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]156
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]157<pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]158 fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i>
159 %Y = tail call fastcc int %FP(double 0.0, int %X) ;<i> tail, fastcc</i>
160 ret int %Y
161 }
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]162</pre>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]163
164<p>In LLVM 1.5, the X86 code generator is the only target that has been enhanced
165to support proper tail calls (other targets will be enhanced in future).
166Further, because this support was added very close to the release, it is
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]167disabled by default. Pass <tt>-enable-x86-fastcc</tt> to llc to enable it (this
168will be enabled by default in the next release). The example above compiles to:
169</p>
170
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]171<pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]172 bar:
173 sub ESP, 8 # Callee uses more space than the caller
174 mov ECX, DWORD PTR [ESP + 8] # Get the old return address
175 mov DWORD PTR [ESP + 4], 0 # First half of 0.0
176 mov DWORD PTR [ESP + 8], 0 # Second half of 0.0
177 mov DWORD PTR [ESP], ECX # Put the return address where it belongs
178 jmp EDX # Tail call "FP"
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]179</pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]180
181<p>
182With fastcc on X86, the first two integer arguments are passed in EAX/EDX, the
183callee pops its arguments off the stack, and the argument area is always a
184multiple of 8 bytes in size.
185</p>
186
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]187</div>
188
189<!--_________________________________________________________________________-->
190<div class="doc_subsubsection">Other New Features</div>
191
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]192<div class="doc_text">
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]193<ol>
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]194 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattnerda1f03c2005-01-22 18:45:35 +0000[diff] [blame]195 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]196 -ipsccp, which is run by default at link-time.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]197 <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data
198 structures use about 30% less memory.</li>
Chris Lattner2e12c742005-02-13 22:27:24 +0000[diff] [blame]199 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]200 href="GettingStartedVS.html">now documented</a>. Most LLVM tools build
201 natively with Visual C++ now.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]202 <li><a href="GettingStarted.html#config">Configuring LLVM to build a subset
203 of the available targets</a> is now implemented, via the
204 <tt>--enable-targets=</tt> option.</li>
Chris Lattnerd7934542005-02-28 16:52:28 +0000[diff] [blame]205 <li>LLVM can now create native shared libraries with '<tt>llvm-gcc ...
206 -shared -Wl,-native</tt>' (or with <tt>-Wl,-native-cbe</tt>).</li>
Chris Lattnerd03b3bc2005-03-11 06:16:26 +0000[diff] [blame]207 <li>LLVM now supports a new "<a href="LangRef.html#i_prefetch">llvm.prefetch
208 </a>" intrinsic, and llvm-gcc now supports __builtin_prefetch.
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]209 <li>LLVM now supports intrinsics for <a href="LangRef.html#int_count">bit
210 counting</a> and llvm-gcc now implements the GCC
211 <tt>__builtin_popcount</tt>, <tt>__builtin_ctz</tt>, and
212 <tt>__builtin_clz</tt> builtins.</li>
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]213 <li>LLVM now mostly builds on HP-UX with the HP aCC Compiler.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]214 <li>The LLVM X86 backend can now emit Cygwin-compatible .s files.</li>
215 <li>LLVM now includes workarounds in the code generator generator which
216 reduces the likelyhood of <a href="http://llvm.cs.uiuc.edu/PR448">GCC
217 hitting swap during optimized builds</a>.</li>
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]218 <li>The <a href="http://llvm.cs.uiuc.edu/ProjectsWithLLVM/#llvmtv">LLVM
219 Transformation Visualizer</a> (llvm-tv) project has been updated to
220 work with LLVM CVS.</li>
221 <li>Nightly tester output is now archived on the <a
222 href="http://mail.cs.uiuc.edu/pipermail/llvm-testresults/">
223 llvm-testresults</a> mailing list.</li>
224
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]225</ol>
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]226</div>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]227
228<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]229<div class="doc_subsection">
230<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattneraab56d42004-05-23 20:42:08 +0000[diff] [blame]231</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]232
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]233<div class="doc_text">
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]234<ol>
Chris Lattner1b592f02005-05-15 06:09:55 +0000[diff] [blame]235<li>The new -simplify-libcalls pass improves code generated for well-known
236library calls. The pass optimizes calls to many of the string, memory, and
237standard I/O functions (e.g. replace the calls with simpler/faster calls) when
238possible, given information known statically about the arguments to the call.
239</li>
240
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]241<li>The -globalopt pass now promotes non-address-taken static globals that are
242only accessed in main to SSA registers.</li>
243
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]244<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]245= 0; &amp;A[i] != &amp;A[n]; ++i) ...</tt>") are optimized better than before,
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]246which primarily helps iterator-intensive C++ codes.</li>
247
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]248<li>The optimizer now eliminates simple cases where redundant conditions exist
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]249 between neighboring blocks.</li>
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]250
251<li>The reassociation pass (which turns (1+X+3) into (X+1+3) among other
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]252things), is more aggressive and intelligent.</li>
253
254<li>The -prune-eh pass now detects no-return functions in addition to the
255 no-unwind functions it did before.</li>
256
257<li>The -globalsmodref alias analysis generates more precise results in some
258 cases.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]259</ol>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]260</div>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]261
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]262
263<!--=========================================================================-->
264<div class="doc_subsection">
265<a name="codequality">Code Generator Improvements in LLVM 1.5</a>
266</div>
267
268<div class="doc_text">
269<ol>
270<li>The code generator now can provide and use information about commutative
271 two-address instructions when performing register allocation.</li>
272
273<li>The code generator now tracks function live-in registers explicitly,
274 instead of requiring the target to generate 'implicit defs' at the
275 entry to a function.</li>
276
277<li>The code generator can lower integer division by a constant to
278 multiplication by a magic constant and multiplication by a constant into
279 shift/add sequences.</li>
280
281<li>The code generator compiles fabs/fneg/sin/cos/sqrt to assembly instructions
282 when possible.</li>
283
284<li>The PowerPC backend generates better code in many cases, making use of
285 FMA instructions and the recording ("dot") forms of various PowerPC
286 instructions.</li>
287</ol>
288</div>
289
290
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]291<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]292<div class="doc_subsection">
293<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]294</div>
295
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]296<div class="doc_text">
297
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]298
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]299<p>Bugs fixed in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]300<ol>
Chris Lattnerbfd24682004-12-29 04:39:50 +0000[diff] [blame]301 <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that
302 are partially overwritten by smaller stores</a></li>
Chris Lattnerf79e57e2005-04-19 06:08:04 +0000[diff] [blame]303 <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
304 setcc or setcc in one case</a></li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]305 <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]306 parser. LLVM 1.0 bytecode files are still supported. </li>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]307</ol>
308
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]309<p>Code Generator Bugs:</p>
310<ol>
311 <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]312 expressions (and/or/xor) not implemented</a>.</li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]313 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]314 respect 'volatile'</a>.</li>
315 <li>The JIT sometimes miscompiled globals and constant pool entries for
316 64-bit integer constants on 32-bit hosts.</li>
Chris Lattnerbf307012005-05-16 16:56:09 +0000[diff] [blame]317 <li>The C backend should no longer produce code that crashes ICC 8.1.</li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]318</ol>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]319
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]320<p>Bugs in the C/C++ front-end:</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]321<ol>
Chris Lattner8de9f232005-01-03 04:20:21 +0000[diff] [blame]322 <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly
323 rejects some constant initializers involving the addresses of array
324 elements</a></li>
Chris Lattnerf832f6a2005-02-11 19:29:52 +0000[diff] [blame]325 <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling
326 anonymous union</a></li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]327 <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic
328 initialization where static init will do</a></li>
Chris Lattner4a9dc292005-02-15 05:28:06 +0000[diff] [blame]329 <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset
330 miscalculated for some structure fields following bit fields</a></li>
Chris Lattner5ad907a2005-02-15 07:02:12 +0000[diff] [blame]331 <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes
332 incorrect for short circuit logical operations</a></li>
Chris Lattnerc1f90a92005-02-19 07:29:25 +0000[diff] [blame]333 <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling
334 bitfield &lt;-&gt; aggregate assignment</a></li>
Chris Lattner94f6ac72005-02-19 17:13:20 +0000[diff] [blame]335 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattnerd12b9b22005-02-19 17:17:32 +0000[diff] [blame]336 virtual function thunk with an unnamed argument</a></li>
Chris Lattner290d2292005-02-20 23:31:49 +0000[diff] [blame]337 <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain
338 C99 complex number routines</a></li>
Chris Lattner2a3cdf72005-02-27 19:31:02 +0000[diff] [blame]339 <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement
340 new on an array type</a></li>
Brian Gaekee77c8e72004-08-24 07:43:48 +0000[diff] [blame]341</ol>
342
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]343</div>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]344
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]345<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]346<div class="doc_section">
347 <a name="portability">Portability and Supported Platforms</a>
348</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]349<!-- *********************************************************************** -->
350
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]351<div class="doc_text">
352
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]353<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]354
355<ul>
356<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
357 other unix-like systems).</li>
358<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]359<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
360 support is available for native builds with Visual C++).</li>
361<li>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]362<li>Alpha-based machines running Debian GNU/Linux.</li>
363<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]364</ul>
365
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]366<p>The core LLVM infrastructure uses
367<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
368to the machine and operating system on which it is built. However, minor
369porting may be required to get LLVM to work on new platforms. We welcome your
370portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]371
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]372</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]373
374<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]375<div class="doc_section">
376 <a name="knownproblems">Known Problems</a>
377</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]378<!-- *********************************************************************** -->
379
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]380<div class="doc_text">
381
382<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]383component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]384sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]385href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]386there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]387
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]388</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]389
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]390<!-- ======================================================================= -->
391<div class="doc_subsection">
392 <a name="experimental">Experimental features included with this release</a>
393</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]394
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]395<div class="doc_text">
396
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]397<p>The following components of this LLVM release are either untested, known to
398be broken or unreliable, or are in early development. These components should
399not be relied on, and bugs should not be filed against them, but they may be
400useful to some people. In particular, if you would like to work on one of these
401components, please contact us on the llvmdev list.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]402
403<ul>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]404<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner1fe848e2005-01-28 06:13:52 +0000[diff] [blame]405 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]406<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
407 be used to step through programs and inspect the stack.</li>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]408<li>The "iterative scan" register allocator (enabled with
409 <tt>-regalloc=iterativescan</tt>) is not stable.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]410<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]411</ul>
412
413</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]414
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]415<!-- ======================================================================= -->
416<div class="doc_subsection">
417 <a name="core">Known problems with the LLVM Core</a>
418</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]419
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]420<div class="doc_text">
421
422<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]423 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
424 work.</li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]425 <li>The JIT does not use mutexes to protect its internal data structures. As
426 such, execution of a threaded program could cause these data structures to be
427 corrupted.
428 </li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]429 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
430 mark values live across a setjmp as volatile</a>. This missing feature
431 only affects targets whose setjmp/longjmp libraries do not save and restore
432 the entire register file.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]433</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]434</div>
435
436<!-- ======================================================================= -->
437<div class="doc_subsection">
438 <a name="c-fe">Known problems with the C front-end</a>
439</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]440
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]441<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]442<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]443
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]444<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]445<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]446<li>C99 Variable sized arrays do not release stack memory when they go out of
447 scope. Thus, the following program may run out of stack space:
448<pre>
449 for (i = 0; i != 1000000; ++i) {
450 int X[n];
451 foo(X);
452 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]453</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]454
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]455<li>Initialization of global union variables can only be done <a
Misha Brukman43ee2932004-12-04 00:45:09 +0000[diff] [blame]456href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]457
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]458</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]459</div>
460
461<!-- _______________________________________________________________________ -->
462<div class="doc_subsubsection">
463 Notes
464</div>
465
466<div class="doc_text">
467
468<ul>
469
470<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]471
472<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]473support for floating point data types of any size other than 32 and 64
474bits.</li>
475
476<li>The following Unix system functionality has not been tested and may not
477work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]478 <ol>
479 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
480 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
481 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
482 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
483 - These functions have not been tested.
484 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]485
486<li>Although many GCC extensions are supported, some are not. In particular,
487 the following extensions are known to <b>not be</b> supported:
488 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]490 <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.</li>
491 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
492 <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>
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]494 <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>
495 <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>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]496 <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>
497 <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>
Tanya Lattner014e5f52004-12-08 18:25:34 +0000[diff] [blame]498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]500 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]501
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]502 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]503 attribute means that the LLVM compiler ignores the presence of the attribute,
504 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]505 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]506 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]507
508 <ol>
509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
510 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]511 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]512
513 <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]514
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]515 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]516 return.<br>
517
518 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]519 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
520 <tt>unused</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]521 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
522
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]523 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]524 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
525 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
526
527 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
528 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
529 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]530
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
532 Specifying attributes of variables.<br>
533 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
534 <tt>deprecated</tt>, <tt>transparent_union</tt>,
535 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]536
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]537 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
538 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
539 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]540 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]541
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]542 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]543 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]544 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]545
546 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
547 all target specific attributes.</li>
548
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
550 Other built-in functions.<br>
551 We support all builtins which have a C language equivalent (e.g.,
552 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
553 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000[diff] [blame]554 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
555 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]556 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
557 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
558 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]559 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]560
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]561 <p>The following extensions <b>are</b> known to be supported:</p>
562
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]563 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]564 <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]565 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
566 <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]567 <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]568 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
569 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
570 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
572 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
573 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
574 <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>
575 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
576 <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]577 <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]578 <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]579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
580or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]581 <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]582 <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]583 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
584 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
585 <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]586 <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]587 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
588 <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>
589 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
590 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
591 <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>
592 <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>
593 <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]594 <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]595 <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>
596 <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]597 </ol></li>
598
599</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]600
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]601<p>If you run into GCC extensions which have not been included in any of these
602lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]603
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]604</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]605
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]606<!-- ======================================================================= -->
607<div class="doc_subsection">
608 <a name="c++-fe">Known problems with the C++ front-end</a>
609</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]610
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]611<div class="doc_text">
612
Reid Spencere09ca642004-12-07 08:39:08 +0000[diff] [blame]613<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]614tested and works for a number of non-trivial programs, including LLVM
615itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]616
617</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]618
619<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]620<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]621
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]622<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]623
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]624<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]625<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]626 front-end</a>.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]627
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]628</ul>
629
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]630</div>
631
632<!-- _______________________________________________________________________ -->
633<div class="doc_subsubsection">
634 Notes
635</div>
636
637<div class="doc_text">
638
639<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]640
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]641<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
642parser is significantly more standards compliant (and picky) than prior GCC
643versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]644href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]645
646<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]647 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]648 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]649 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]650 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]651
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]652<li>The LLVM C++ front-end follows the <a
653 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
654 This document, which is not Itanium specific, specifies a standard for name
655 mangling, class layout, v-table layout, RTTI formats, and other C++
656 representation issues. Because we use this API, code generated by the LLVM
657 compilers should be binary compatible with machine code generated by other
658 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
659 <i>However</i>, the exception handling mechanism used by LLVM is very
660 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]661 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]662
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]663</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]664
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]665</div>
666
667<!-- ======================================================================= -->
668<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]669 <a name="c-be">Known problems with the C back-end</a>
670</div>
671
672<div class="doc_text">
673
674<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]675
676<li>The C back-end produces code that violates the ANSI C Type-Based Alias
677Analysis rules. As such, special options may be necessary to compile the code
678(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]679problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]680
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]681<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]682supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]683frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]684
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]685</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]686
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]687</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]688
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]689<!-- ======================================================================= -->
690<div class="doc_subsection">
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]691 <a name="x86-be">Known problems with the X86 back-end</a>
692</div>
693
694<div class="doc_text">
695
696<ul>
697 <li>None yet</li>
698</ul>
699
700</div>
701
702<!-- ======================================================================= -->
703<div class="doc_subsection">
704 <a name="ppc-be">Known problems with the PowerPC back-end</a>
705</div>
706
707<div class="doc_text">
708
709<ul>
710<li>None yet</li>
711</ul>
712
713</div>
714
715<!-- ======================================================================= -->
716<div class="doc_subsection">
717 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
718</div>
719
720<div class="doc_text">
721
722<ul>
723<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
724several programs in the LLVM test suite</a></li>
725</ul>
726
727</div>
728
729<!-- ======================================================================= -->
730<div class="doc_subsection">
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]731 <a name="alpha-be">Known problems with the Alpha back-end</a>
732</div>
733
734<div class="doc_text">
735
736<ul>
737
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]738<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
739appropriate nops inserted to ensure restartability.</li>
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]740
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]741<li>Defining vararg functions is not supported (but calling them is ok).</li>
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]742
Andrew Lenharth01f40b32005-05-14 17:43:00 +0000[diff] [blame]743<li>Due to the vararg problems, C++ exceptions do not work. Small changes are required to the CFE (which break correctness in the exception handler) to compile the exception handling library (and thus the C++ standard library).</li>
744
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]745</ul>
746
747</div>
748
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]749<!-- ======================================================================= -->
750<div class="doc_subsection">
751 <a name="ia64-be">Known problems with the IA64 back-end</a>
752</div>
753
754<div class="doc_text">
755
756<ul>
757
758<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
759made where the argument is not 16-byte aligned, as required on IA64. (Strictly
760speaking this is not a bug in the IA64 back-end; it will also be encountered
761when building C++ programs using the C back-end.)</li>
762
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]763<li>The C++ front-end does not use <a href="http://llvm.cs.uiuc.edu/PR406">IA64
764ABI compliant layout of v-tables</a>. In particular, it just stores function
765pointers instead of function descriptors in the vtable. This bug prevents
766mixing C++ code compiled with LLVM with C++ objects compiled by other C++
767compilers.</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]768
Chris Lattnerf9b1f462005-05-16 17:06:29 +0000[diff] [blame]769<li>There are a few ABI violations which will lead to problems when mixing LLVM
770output with code built with other compilers, particularly for floating-point
771programs.</li>
772
773<li>Defining vararg functions is not supported (but calling them is ok).</li>
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]774
775</ul>
776
777</div>
778
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]779<!-- ======================================================================= -->
780<div class="doc_subsection">
781 <a name="sparcv8">Known problems with the SPARC-V8 back-end</a>
782</div>
783
784<div class="doc_text">
785
786<ul>
787<li>Many features are still missing (e.g. support for 64-bit integer
788arithmetic).</li>
789
790<li>This backend needs to be updated to use the SelectionDAG instruction
791selection framework.</li>
792</ul>
793
794</div>
795
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]796<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]797<div class="doc_section">
798 <a name="additionalinfo">Additional Information</a>
799</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]800<!-- *********************************************************************** -->
801
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]802<div class="doc_text">
803
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame^]804<p>A wide variety of additional information is available on the <a
805href="http://llvm.cs.uiuc.edu">LLVM web page</a>, including <a
806href="http://llvm.cs.uiuc.edu/docs/">documentation</a> and <a
807href="http://llvm.cs.uiuc.edu/pubs/">publications describing algorithms and
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]808components implemented in LLVM</a>. The web page also contains versions of the
809API documentation which is up-to-date with the CVS version of the source code.
810You can access versions of these documents specific to this release by going
811into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]812
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]813<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner416db102005-05-16 17:13:10 +0000[diff] [blame^]814us via the <a href="http://llvm.cs.uiuc.edu/docs/#maillist"> mailing
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]815lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]816
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]817</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]818
819<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]820
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]821<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]822<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]823 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]824 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
825 <a href="http://validator.w3.org/check/referer"><img
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827
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]828 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]829 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]830</address>
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Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]832</body>
833</html>