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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 775afa5ec028df7a2b64c29787cb04d907ba13c0 / . / 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 Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]65<p> At this time, LLVM is known to correctly compile a wide range of C and C++
66programs, including the SPEC CPU95 &amp; 2000 suite. It includes bug fixes for
67those problems found since the 1.4 release and a large number of new features
68and enhancements, described below.</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]69
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]70</div>
71
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]72<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]73<div class="doc_subsection">
74<a name="newfeatures">New Features in LLVM 1.5</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]75</div>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]76
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]77<!--_________________________________________________________________________-->
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]78<div class="doc_subsubsection"><a name="newcg">New Native Code
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]79Generators</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]80
81<div class="doc_text">
82<p>
83This release includes new native code generators for <a
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]84href="#alpha-be">Alpha</a>, <a href="#ia64-be">IA-64</a>, and <a
85href="#sparcv8">SPARC-V8</a> (32-bit SPARC). These code generators are still
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]86beta quality, but are progressing rapidly. The Alpha backend is implemented
87with an eye towards being compatible with the widely used SimpleScalar
88simulator.
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]89</p>
90</div>
91
92<!--_________________________________________________________________________-->
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]93<div class="doc_subsubsection"><a name="selectiondag">New Instruction
94Selector Framework</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]95
96<div class="doc_text">
97<p>This release includes a <a href="CodeGenerator.html#instselect">new framework
98for building instruction selectors</a>, which has long been the hardest part of
99building a new LLVM target. This framework handles a lot of the mundane (but
100easy to get wrong) details of writing the instruction selector, such as
101generating efficient code for <a
102href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting
103small integer types to larger types (e.g. for RISC targets with one size of
104integer registers), expanding 64-bit integer operations for 32-bit hosts, etc.
105Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The
106SPARC backends will be migrated when time permits.
107</p>
108</div>
109
110<!--_________________________________________________________________________-->
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]111<div class="doc_subsubsection"><a name="customccs">New Support for Per-Function
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]112Calling Conventions</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]113
114<div class="doc_text">
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]115<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">per-function
116calling conventions</a>. Traditionally, the LLVM code generators match the
117native C calling conventions for a target. This is important for compatibility,
118but is not very flexible. This release allows custom calling conventions to be
119established for functions, and defines three target-independent conventions (<a
120href="LangRef.html#callingconv">C call, fast call, and cold call</a>) which may
121be supported by code generators. When possible, the LLVM optimizer promotes C
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]122functions to use the "fastcc" convention, allowing the use of more efficient
123calling sequences (e.g., parameters are passed in registers in the X86 target).
124</p>
125
126<p>Targets may now also define target-specific calling conventions, allowing
127LLVM to fully support calling convention altering options (e.g. GCC's
128<tt>-mregparm</tt> flag) and well-defined target conventions (e.g. stdcall and
129fastcall on X86).</p>
130</div>
131
132<!--_________________________________________________________________________-->
Chris Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]133<div class="doc_subsubsection"><a name="tailcalls">New Support for
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]134Proper Tail Calls</a></div>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]135
136<div class="doc_text">
137<p>The release now includes support for <a
138href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as
139required to implement languages like Scheme. Tail calls make use of two
140features: custom calling conventions (described above), which allow the code
141generator to emit code for the caller to deallocate its own stack when it
142returns. 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]143instruction</a>, which indicates that the callee does not access the caller's
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]144stack frame (indicating that it is acceptable to deallocate the caller stack
145before invoking the callee). LLVM proper tail calls run on the system stack (as
146do normal calls), supports indirect tail calls, tail calls with arbitrary
147numbers of arguments, tail calls where the callee requires more argument space
148than the caller, etc. The only case not supported are varargs calls, but that
149could be added if desired.
150</p>
151
152<p>In order for a front-end to get guaranteed tail call, it must mark functions
153as "fastcc", mark calls with the 'tail' marker, and follow the call with a
154return of the called value (or void). The optimizer and code generator attempt
155to handle more general cases, but the simple case will always work if the code
156generator supports tail calls. Here is a simple example:</p>
157
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]158<pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]159 fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i>
160 %Y = tail call fastcc int %FP(double 0.0, int %X) ;<i> tail, fastcc</i>
161 ret int %Y
162 }
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]163</pre>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]164
165<p>In LLVM 1.5, the X86 code generator is the only target that has been enhanced
166to support proper tail calls (other targets will be enhanced in future).
167Further, because this support was added very close to the release, it is
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]168disabled by default. Pass <tt>-enable-x86-fastcc</tt> to llc to enable it (this
169will be enabled by default in the next release). The example above compiles to:
170</p>
171
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]172<pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]173 bar:
174 sub ESP, 8 # Callee uses more space than the caller
175 mov ECX, DWORD PTR [ESP + 8] # Get the old return address
176 mov DWORD PTR [ESP + 4], 0 # First half of 0.0
177 mov DWORD PTR [ESP + 8], 0 # Second half of 0.0
178 mov DWORD PTR [ESP], ECX # Put the return address where it belongs
179 jmp EDX # Tail call "FP"
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]180</pre>
Chris Lattnera4faa4a2005-05-15 06:07:40 +0000[diff] [blame]181
182<p>
183With fastcc on X86, the first two integer arguments are passed in EAX/EDX, the
184callee pops its arguments off the stack, and the argument area is always a
185multiple of 8 bytes in size.
186</p>
187
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]188</div>
189
190<!--_________________________________________________________________________-->
191<div class="doc_subsubsection">Other New Features</div>
192
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]193<div class="doc_text">
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]194<ol>
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]195 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattnerda1f03c2005-01-22 18:45:35 +0000[diff] [blame]196 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]197 -ipsccp, which is run by default at link-time.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]198 <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data
199 structures use about 30% less memory.</li>
Chris Lattner2e12c742005-02-13 22:27:24 +0000[diff] [blame]200 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattnera5d803e2005-02-14 22:58:38 +0000[diff] [blame]201 href="GettingStartedVS.html">now documented</a>.</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 Lattnerb38da0f2005-05-15 15:33:21 +0000[diff] [blame]218 <li>The PowerPC backend generates far better code than in LLVM 1.4.</li>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]219</ol>
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]220</div>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]221
222<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]223<div class="doc_subsection">
224<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattneraab56d42004-05-23 20:42:08 +0000[diff] [blame]225</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]226
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]227<div class="doc_text">
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]228<ol>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]229<li>The -globalopt pass now promotes non-address-taken static globals that are
230only accessed in main to SSA registers.</li>
231
Chris Lattner1b592f02005-05-15 06:09:55 +0000[diff] [blame]232<li>The new -simplify-libcalls pass improves code generated for well-known
233library calls. The pass optimizes calls to many of the string, memory, and
234standard I/O functions (e.g. replace the calls with simpler/faster calls) when
235possible, given information known statically about the arguments to the call.
236</li>
237
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]238<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i
239= 0; &amp;A[i] != &amp;A[100]; ++i) ...</tt>") are optimized better than before,
240which primarily helps iterator-intensive C++ codes.</li>
241
Chris Lattner77d36d42005-05-16 15:37:19 +0000[diff] [blame]242<li>The code generator now can provide and use information about commutative
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]243two-address instructions when performing register allocation.</li>
244
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]245<li>The optimizer now eliminates simple cases where redundant conditions exist
246between neighboring blocks.</li>
247
248<li>The reassociation pass (which turns (1+X+3) into (X+1+3) among other
249things), is more aggressive an intelligent.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]250
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]251</ol>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]252</div>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]253
254<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]255<div class="doc_subsection">
256<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]257</div>
258
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]259<div class="doc_text">
260
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]261
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]262<p>Bugs fixed in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]263<ol>
Chris Lattnerbfd24682004-12-29 04:39:50 +0000[diff] [blame]264 <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that
265 are partially overwritten by smaller stores</a></li>
Chris Lattnerf79e57e2005-04-19 06:08:04 +0000[diff] [blame]266 <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
267 setcc or setcc in one case</a></li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame]268 <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
269 parser. LLVM 1.0 bytecode files are still supported. </li>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]270</ol>
271
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]272<p>Code Generator Bugs:</p>
273<ol>
274 <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]275 expressions (and/or/xor) not implemented</a>.</li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]276 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
Chris Lattner20514d12005-05-16 06:58:39 +0000[diff] [blame]277 respect 'volatile'</a>.</li>
278 <li>The JIT sometimes miscompiled globals and constant pool entries for
279 64-bit integer constants on 32-bit hosts.</li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]280</ol>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]281
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]282<p>Bugs in the C/C++ front-end:</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]283<ol>
Chris Lattner8de9f232005-01-03 04:20:21 +0000[diff] [blame]284 <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly
285 rejects some constant initializers involving the addresses of array
286 elements</a></li>
Chris Lattnerf832f6a2005-02-11 19:29:52 +0000[diff] [blame]287 <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling
288 anonymous union</a></li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]289 <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic
290 initialization where static init will do</a></li>
Chris Lattner4a9dc292005-02-15 05:28:06 +0000[diff] [blame]291 <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset
292 miscalculated for some structure fields following bit fields</a></li>
Chris Lattner5ad907a2005-02-15 07:02:12 +0000[diff] [blame]293 <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes
294 incorrect for short circuit logical operations</a></li>
Chris Lattnerc1f90a92005-02-19 07:29:25 +0000[diff] [blame]295 <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling
296 bitfield &lt;-&gt; aggregate assignment</a></li>
Chris Lattner94f6ac72005-02-19 17:13:20 +0000[diff] [blame]297 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattnerd12b9b22005-02-19 17:17:32 +0000[diff] [blame]298 virtual function thunk with an unnamed argument</a></li>
Chris Lattner290d2292005-02-20 23:31:49 +0000[diff] [blame]299 <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain
300 C99 complex number routines</a></li>
Chris Lattner2a3cdf72005-02-27 19:31:02 +0000[diff] [blame]301 <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement
302 new on an array type</a></li>
Brian Gaekee77c8e72004-08-24 07:43:48 +0000[diff] [blame]303</ol>
304
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]305</div>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]306
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]307<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]308<div class="doc_section">
309 <a name="portability">Portability and Supported Platforms</a>
310</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]311<!-- *********************************************************************** -->
312
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]313<div class="doc_text">
314
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]315<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]316
317<ul>
318<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
319 other unix-like systems).</li>
320<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]321<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
322 support is available for native builds with Visual C++).</li>
323<li>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]324<li>Alpha-based machines running Debian GNU/Linux.</li>
325<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]326</ul>
327
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]328<p>The core LLVM infrastructure uses
329<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
330to the machine and operating system on which it is built. However, minor
331porting may be required to get LLVM to work on new platforms. We welcome your
332portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]333
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]334</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]335
336<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]337<div class="doc_section">
338 <a name="knownproblems">Known Problems</a>
339</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]340<!-- *********************************************************************** -->
341
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]342<div class="doc_text">
343
344<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]345component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]346sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]347href="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]348there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]349
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]350</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]351
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]352<!-- ======================================================================= -->
353<div class="doc_subsection">
354 <a name="experimental">Experimental features included with this release</a>
355</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]356
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]357<div class="doc_text">
358
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]359<p>The following components of this LLVM release are either untested, known to
360be broken or unreliable, or are in early development. These components should
361not be relied on, and bugs should not be filed against them, but they may be
362useful to some people. In particular, if you would like to work on one of these
363components, please contact us on the llvmdev list.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]364
365<ul>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]366<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner1fe848e2005-01-28 06:13:52 +0000[diff] [blame]367 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]368<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
369 be used to step through programs and inspect the stack.</li>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]370<li>The "iterative scan" register allocator (enabled with
371 <tt>-regalloc=iterativescan</tt>) is not stable.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]372<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]373</ul>
374
375</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]376
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]377<!-- ======================================================================= -->
378<div class="doc_subsection">
379 <a name="core">Known problems with the LLVM Core</a>
380</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]381
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]382<div class="doc_text">
383
384<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]385 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
386 work.</li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]387 <li>The JIT does not use mutexes to protect its internal data structures. As
388 such, execution of a threaded program could cause these data structures to be
389 corrupted.
390 </li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]391 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
392 mark values live across a setjmp as volatile</a>. This missing feature
393 only affects targets whose setjmp/longjmp libraries do not save and restore
394 the entire register file.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]395</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]396</div>
397
398<!-- ======================================================================= -->
399<div class="doc_subsection">
400 <a name="c-fe">Known problems with the C front-end</a>
401</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]402
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]403<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]404<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]405
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]406<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]407<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]408<li>C99 Variable sized arrays do not release stack memory when they go out of
409 scope. Thus, the following program may run out of stack space:
410<pre>
411 for (i = 0; i != 1000000; ++i) {
412 int X[n];
413 foo(X);
414 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]415</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]416
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]417<li>Initialization of global union variables can only be done <a
Misha Brukman43ee2932004-12-04 00:45:09 +0000[diff] [blame]418href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]419
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]420</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]421</div>
422
423<!-- _______________________________________________________________________ -->
424<div class="doc_subsubsection">
425 Notes
426</div>
427
428<div class="doc_text">
429
430<ul>
431
432<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]433
434<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]435support for floating point data types of any size other than 32 and 64
436bits.</li>
437
438<li>The following Unix system functionality has not been tested and may not
439work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]440 <ol>
441 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
442 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
443 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
444 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
445 - These functions have not been tested.
446 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]447
448<li>Although many GCC extensions are supported, some are not. In particular,
449 the following extensions are known to <b>not be</b> supported:
450 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]451 <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]452 <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>
453 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
454 <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]455 <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]456 <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>
457 <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]458 <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>
459 <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]460 <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]461 <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]462 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]463
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]464 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]465 attribute means that the LLVM compiler ignores the presence of the attribute,
466 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]467 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]468 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]469
470 <ol>
471 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
472 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]473 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]474
475 <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]476
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]477 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]478 return.<br>
479
480 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]481 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
482 <tt>unused</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]483 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
484
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]485 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]486 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
487 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
488
489 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
490 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
491 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]492
493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
494 Specifying attributes of variables.<br>
495 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
496 <tt>deprecated</tt>, <tt>transparent_union</tt>,
497 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]498
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]499 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
500 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
501 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]502 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]503
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]504 <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]505 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]506 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]507
508 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
509 all target specific attributes.</li>
510
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]511 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
512 Other built-in functions.<br>
513 We support all builtins which have a C language equivalent (e.g.,
514 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
515 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000[diff] [blame]516 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
517 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]518 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
519 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
520 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]521 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]522
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]523 <p>The following extensions <b>are</b> known to be supported:</p>
524
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]525 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]526 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]527 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
528 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
Tanya Lattnerca26c3e2004-06-22 03:48:17 +0000[diff] [blame]529 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]530 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
532 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
533 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
534 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
536 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
537 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
538 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/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]539 <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]540 <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]541 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
542or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]543 <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]544 <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]545 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
546 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
547 <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]548 <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]549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
550 <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>
551 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
552 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
553 <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>
554 <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>
555 <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]556 <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]557 <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>
558 <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]559 </ol></li>
560
561</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]562
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]563<p>If you run into GCC extensions which have not been included in any of these
564lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]565
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]566</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]567
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]568<!-- ======================================================================= -->
569<div class="doc_subsection">
570 <a name="c++-fe">Known problems with the C++ front-end</a>
571</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]572
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]573<div class="doc_text">
574
Reid Spencere09ca642004-12-07 08:39:08 +0000[diff] [blame]575<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]576tested and works for a number of non-trivial programs, including LLVM
577itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]578
579</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]580
581<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]582<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]583
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]584<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]585
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]586<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]587<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]588 front-end</a>.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]589
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]590<li><b>IA-64 specific</b>: The C++ front-end does not use <a
591href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]592In particular, it just stores function pointers instead of function
593descriptors in the vtable. This bug prevents mixing C++ code compiled with
Chris Lattner04db8082004-08-02 20:29:51 +0000[diff] [blame]594LLVM with C++ objects compiled by other C++ compilers.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]595
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]596</ul>
597
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]598</div>
599
600<!-- _______________________________________________________________________ -->
601<div class="doc_subsubsection">
602 Notes
603</div>
604
605<div class="doc_text">
606
607<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]608
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]609<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
610parser is significantly more standards compliant (and picky) than prior GCC
611versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]612href="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]613
614<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]615 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]616 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]617 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]618 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]619
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]620<li>The LLVM C++ front-end follows the <a
621 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
622 This document, which is not Itanium specific, specifies a standard for name
623 mangling, class layout, v-table layout, RTTI formats, and other C++
624 representation issues. Because we use this API, code generated by the LLVM
625 compilers should be binary compatible with machine code generated by other
626 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
627 <i>However</i>, the exception handling mechanism used by LLVM is very
628 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]629 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]630
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]631</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]632
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]633</div>
634
635<!-- ======================================================================= -->
636<div class="doc_subsection">
637 <a name="x86-be">Known problems with the X86 back-end</a>
638</div>
639
640<div class="doc_text">
641
642<ul>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]643 <li>None yet</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]644</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]645
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]646</div>
647
648<!-- ======================================================================= -->
649<div class="doc_subsection">
Misha Brukmanadb1c392004-07-12 16:55:41 +0000[diff] [blame]650 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]651</div>
652
653<div class="doc_text">
654
655<ul>
Misha Brukmanadb1c392004-07-12 16:55:41 +0000[diff] [blame]656<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
657several programs in the LLVM test suite</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]658</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]659
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]660</div>
661
662<!-- ======================================================================= -->
663<div class="doc_subsection">
Chris Lattnerf32a5f52004-11-07 01:55:32 +0000[diff] [blame]664 <a name="ppc-be">Known problems with the PowerPC back-end</a>
665</div>
666
667<div class="doc_text">
668
669<ul>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]670<li>None yet</li>
Chris Lattnerf32a5f52004-11-07 01:55:32 +0000[diff] [blame]671</ul>
672
673</div>
674
675<!-- ======================================================================= -->
676<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]677 <a name="c-be">Known problems with the C back-end</a>
678</div>
679
680<div class="doc_text">
681
682<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]683
684<li>The C back-end produces code that violates the ANSI C Type-Based Alias
685Analysis rules. As such, special options may be necessary to compile the code
686(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]687problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]688
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]689<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]690supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]691frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]692
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]693</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]694
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]695</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]696
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]697<!-- ======================================================================= -->
698<div class="doc_subsection">
699 <a name="alpha-be">Known problems with the Alpha back-end</a>
700</div>
701
702<div class="doc_text">
703
704<ul>
705
706<li>On 21164s, some rare FP arithmatic sequences which may trap do not have the appropriate nops inserted to ensure restartability.</li>
707
708<li>Vararg functions are not supported.</li>
709
Andrew Lenharth01f40b32005-05-14 17:43:00 +0000[diff] [blame]710<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>
711
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]712</ul>
713
714</div>
715
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]716<!-- ======================================================================= -->
717<div class="doc_subsection">
718 <a name="ia64-be">Known problems with the IA64 back-end</a>
719</div>
720
721<div class="doc_text">
722
723<ul>
724
725<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
726made where the argument is not 16-byte aligned, as required on IA64. (Strictly
727speaking this is not a bug in the IA64 back-end; it will also be encountered
728when building C++ programs using the C back-end.)</li>
729
730<li>There are a few ABI violations which will lead to problems
731when mixing LLVM output with code built with other compilers,
732particularly for C++ and floating-point programs.</li>
733
734<li>Vararg functions are not supported.</li>
735
736</ul>
737
738</div>
739
Chris Lattner98a493c2005-05-15 16:01:20 +0000[diff] [blame]740<!-- ======================================================================= -->
741<div class="doc_subsection">
742 <a name="sparcv8">Known problems with the SPARC-V8 back-end</a>
743</div>
744
745<div class="doc_text">
746
747<ul>
748<li>Many features are still missing (e.g. support for 64-bit integer
749arithmetic).</li>
750
751<li>This backend needs to be updated to use the SelectionDAG instruction
752selection framework.</li>
753</ul>
754
755</div>
756
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]757<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]758<div class="doc_section">
759 <a name="additionalinfo">Additional Information</a>
760</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]761<!-- *********************************************************************** -->
762
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]763<div class="doc_text">
764
765<p>A wide variety of additional information is available on the LLVM web page,
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]766including <a href="http://llvm.cs.uiuc.edu/docs/#maillist">mailing lists</a> and
767<a href="http://llvm.cs.uiuc.edu/pubs/">publications describing algorithms and
768components implemented in LLVM</a>. The web page also contains versions of the
769API documentation which is up-to-date with the CVS version of the source code.
770You can access versions of these documents specific to this release by going
771into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]772
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]773<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]774us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
775lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]776
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]777</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]778
779<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]780
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]781<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]782<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]783 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]784 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
785 <a href="http://validator.w3.org/check/referer"><img
786 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
787
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]788 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]789 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]790</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]791
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]792</body>
793</html>