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Chris Lattnerf3a7c242004-12-09 22:22:58 +0000[diff] [blame]7 <title>LLVM 1.5 Release Notes</title>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]8</head>
9<body>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]10
Chris Lattnerf3a7c242004-12-09 22:22:58 +0000[diff] [blame]11<div class="doc_title">LLVM 1.5 Release Notes</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]12
13<ol>
Misha Brukman80731b92003-11-22 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 Lattner77a51732004-04-30 22:17:12 +0000[diff] [blame]16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]17 <li><a href="#portability">Portability and Supported Platforms</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]18 <li><a href="#knownproblems">Known Problems</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]19 <li><a href="#additionalinfo">Additional Information</a></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]20</ol>
21
Chris Lattner020e1fc2004-05-23 21:07:27 +0000[diff] [blame]22<div class="doc_author">
Chris Lattnerf3a7c242004-12-09 22:22:58 +0000[diff] [blame]23 <p>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM Team</a><p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]24</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]25
26<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]27<div class="doc_section">
28 <a name="intro">Introduction</a>
29</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]30<!-- *********************************************************************** -->
31
Misha Brukman80731b92003-11-22 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 Lattnerf3a7c242004-12-09 22:22:58 +0000[diff] [blame]35infrastructure, release 1.5. Here we describe the status of LLVM, including any
Chris Lattner406bddf2005-05-15 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 Lattnerf3a7c242004-12-09 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 Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]39not reading this on the LLVM web pages, you should probably go there because
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]40this document may be updated after the release.</p>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]41
Chris Lattnerb5bb5972004-12-07 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 Lattnere7525b52003-10-07 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]46list</a> is a good place to send them.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]47
Chris Lattnerf3a7c242004-12-09 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]51href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
52
53</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]54
55<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]56<div class="doc_section">
57 <a name="whatsnew">What's New?</a>
58</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]59<!-- *********************************************************************** -->
60
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]61<div class="doc_text">
62
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]63<p>This is the sixth public release of the LLVM Compiler Infrastructure.</p>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]64
Chris Lattner406bddf2005-05-15 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 Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]69
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]70</div>
71
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]72<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]73<div class="doc_subsection">
74<a name="newfeatures">New Features in LLVM 1.5</a>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]75</div>
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]76
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]77<!--_________________________________________________________________________-->
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]78<div class="doc_subsubsection"><a name="newcg">New Native Code
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]79Generators</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]80
81<div class="doc_text">
82<p>
83This release includes new native code generators for <a
Chris Lattnerb62a5f02005-05-15 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 Lattnera3ea6442005-05-16 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 Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]89</p>
90</div>
91
92<!--_________________________________________________________________________-->
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]93<div class="doc_subsubsection"><a name="selectiondag">New Instruction
94Selector Framework</a></div>
Chris Lattner406bddf2005-05-15 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 Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame^]111<div class="doc_subsubsection"><a name="customccs">New Support for Per-Function
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]112Calling Conventions</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]113
114<div class="doc_text">
Chris Lattnera3ea6442005-05-16 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 Lattner406bddf2005-05-15 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 Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]133<div class="doc_subsubsection"><a name="tailcalls">New Support for
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame^]134Proper Tail Calls</a></div>
Chris Lattner406bddf2005-05-15 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 Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]143instruction</a>, which indicates that the callee does not access the caller's
Chris Lattner406bddf2005-05-15 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 Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]158<pre>
Chris Lattner55f987b2005-05-15 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 Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]163</pre>
Chris Lattner406bddf2005-05-15 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 Lattner55f987b2005-05-15 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 Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]172<pre>
Chris Lattner55f987b2005-05-15 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 Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]180</pre>
Chris Lattner55f987b2005-05-15 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 Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]188</div>
189
190<!--_________________________________________________________________________-->
191<div class="doc_subsubsection">Other New Features</div>
192
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]193<div class="doc_text">
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]194<ol>
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]195 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattner64d9d2b2005-01-22 18:45:35 +0000[diff] [blame]196 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]197 -ipsccp, which is run by default at link-time.</li>
Chris Lattner406bddf2005-05-15 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 Lattnere14babd2005-02-13 22:27:24 +0000[diff] [blame]200 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattnerbe895ed2005-02-14 22:58:38 +0000[diff] [blame]201 href="GettingStartedVS.html">now documented</a>.</li>
Chris Lattner406bddf2005-05-15 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 Lattner81c1dd22005-02-28 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 Lattnerdb302f82005-03-11 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 Lattnerb34b2732005-05-07 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 Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame^]213 <li>LLVM now mostly builds on HP-UX with the HP aCC Compiler.</li>
Chris Lattner406bddf2005-05-15 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 Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]218 <li>The PowerPC backend generates far better code than in LLVM 1.4.</li>
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]219</ol>
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]220</div>
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]221
222<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]223<div class="doc_subsection">
224<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattner23257062004-05-23 20:42:08 +0000[diff] [blame]225</div>
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]226
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]227<div class="doc_text">
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]228<ol>
Chris Lattner406bddf2005-05-15 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 Lattner17b2e482005-05-15 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 Lattner406bddf2005-05-15 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
242<li>The code generator now uses information about takes advantage of commutative
243two-address instructions when performing register allocation.</li>
244
Chris Lattnera3ea6442005-05-16 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 Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]250
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]251</ol>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]252</div>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]253
254<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]255<div class="doc_subsection">
256<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]257</div>
258
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]259<div class="doc_text">
260
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]261
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]262<p>Bugs fixed in the LLVM Core:</p>
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]263<ol>
Chris Lattnerb5c253a2004-12-29 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 Lattner181c8182005-04-19 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 Lattner406bddf2005-05-15 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 Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]270</ol>
271
Chris Lattner1c75b252005-02-14 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 Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame^]275 expressions (and/or/xor) not implemented</a>.</li>
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]276 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
Chris Lattnera3ea6442005-05-16 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 Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]280</ol>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]281
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]282<p>Bugs in the C/C++ front-end:</p>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]283<ol>
Chris Lattnere1329f42005-01-03 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 Lattner2a38aea2005-02-11 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 Lattner1c75b252005-02-14 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 Lattner1f031b22005-02-15 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 Lattner385a4732005-02-15 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 Lattner48c23142005-02-19 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 Lattner6a3ae642005-02-19 17:13:20 +0000[diff] [blame]297 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattner3d6194f2005-02-19 17:17:32 +0000[diff] [blame]298 virtual function thunk with an unnamed argument</a></li>
Chris Lattner3a8f68e2005-02-20 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 Lattnerc6e33802005-02-27 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 Gaeke730d8d62004-08-24 07:43:48 +0000[diff] [blame]303</ol>
304
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]305</div>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]306
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]307<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]308<div class="doc_section">
309 <a name="portability">Portability and Supported Platforms</a>
310</div>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]311<!-- *********************************************************************** -->
312
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]313<div class="doc_text">
314
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]315<p>LLVM is known to work on the following platforms:</p>
Chris Lattner2c7b0872004-06-01 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 Lattnerb5bb5972004-12-07 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 Criswelld5234922005-05-13 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 Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]326</ul>
327
Brian Gaekee3e557e2004-05-09 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]333
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]334</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]335
336<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]337<div class="doc_section">
338 <a name="knownproblems">Known Problems</a>
339</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]340<!-- *********************************************************************** -->
341
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]345component. As new problems are discovered, they will be added to these
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]346sections. If you run into a problem, please check the <a
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]347href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]348there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]349
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]350</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]351
Chris Lattnerb911de42004-03-14 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]356
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]357<div class="doc_text">
358
Misha Brukmanfa50a222004-05-12 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 Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]364
365<ul>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]366<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner38389b12005-01-28 06:13:52 +0000[diff] [blame]367 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattnerb5bb5972004-12-07 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 Brukman96158092005-03-30 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 Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]372<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]373</ul>
374
375</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]376
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]381
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]382<div class="doc_text">
383
384<ul>
Misha Brukman96158092005-03-30 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 Spencer493d9c22004-11-25 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 Spencer493d9c22004-11-25 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]395</ul>
Misha Brukman80731b92003-11-22 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 Lattner178f3db2003-10-02 05:07:23 +0000[diff] [blame]402
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]403<!-- _______________________________________________________________________ -->
Chris Lattner5a8a7282003-12-14 05:03:43 +0000[diff] [blame]404<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]405
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]406<div class="doc_text">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]407<ul>
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]415</pre></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]416
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]417<li>Initialization of global union variables can only be done <a
Misha Brukman68ef9a92004-12-04 00:45:09 +0000[diff] [blame]418href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattner1ab58dd2004-03-16 21:39:04 +0000[diff] [blame]419
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]420</ul>
Misha Brukman80731b92003-11-22 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 Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]433
434<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 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 Brukman80731b92003-11-22 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 Criswell86a3a482003-12-18 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 Brukman80731b92003-11-22 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 Brukman80731b92003-11-22 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 Lattner63371342004-12-08 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 Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]462 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]463
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]464 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner3d482502003-10-02 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 Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]467 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]468 the program.</p>
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]473 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]476
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]477 Declaring that functions have no side effects or that they can never
Misha Brukman80731b92003-11-22 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 Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]481 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
482 <tt>unused</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]483 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
484
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]485 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]498
Chris Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]502 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]503
Misha Brukman8395d732003-12-12 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]505 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]506 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Lattnerb7c4bac2004-06-18 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 Lattnerb34b2732005-05-07 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]521 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]522
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]523 <p>The following extensions <b>are</b> known to be supported:</p>
524
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]525 <ol>
Chris Lattnerd3dc8502004-03-16 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 Brukman80731b92003-11-22 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 Lattnerce33a1b2004-06-22 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 Brukman80731b92003-11-22 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 Brukman8395d732003-12-12 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 Brukman80731b92003-11-22 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 Criswell86a3a482003-12-18 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 Brukman80731b92003-11-22 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 Brukman8395d732003-12-12 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 Brukman80731b92003-11-22 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 Lattner7591b822004-12-08 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 Brukman80731b92003-11-22 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 Lattner3646dad2004-02-14 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 Brukman80731b92003-11-22 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 Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]559 </ol></li>
560
561</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]562
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]565
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]566</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]567
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]572
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]573<div class="doc_text">
574
Reid Spencer55684c32004-12-07 08:39:08 +0000[diff] [blame]575<p>For this release, the C++ front-end is considered to be fully
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]576tested and works for a number of non-trivial programs, including LLVM
577itself.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]578
579</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]580
581<!-- _______________________________________________________________________ -->
Chris Lattner141ebb62004-02-14 04:12:41 +0000[diff] [blame]582<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]583
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]584<div class="doc_text">
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]585
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]586<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]587<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]588 front-end</a>.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]589
Chris Lattner5cd40922004-08-02 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 Lattner041e6c92004-07-17 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 Lattner2fd93492004-08-02 20:29:51 +0000[diff] [blame]594LLVM with C++ objects compiled by other C++ compilers.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]595
Chris Lattner5cd40922004-08-02 20:28:44 +0000[diff] [blame]596</ul>
597
Misha Brukman80731b92003-11-22 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 Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]608
Chris Lattner3d482502003-10-02 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 Lattnere76e9ab2003-12-12 04:25:33 +0000[diff] [blame]612href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]613
614<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]615 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]616 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]617 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]618 better than most compilers).</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]619
Chris Lattner62495762003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]629 interact correctly</b>. </li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]630
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]631</ul>
Chris Lattner46ecf612003-10-07 22:14:37 +0000[diff] [blame]632
Misha Brukman80731b92003-11-22 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 Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]643 <li>None yet</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]644</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]645
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]646</div>
647
648<!-- ======================================================================= -->
649<div class="doc_subsection">
Misha Brukmana516e992004-07-12 16:55:41 +0000[diff] [blame]650 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]651</div>
652
653<div class="doc_text">
654
655<ul>
Misha Brukmana516e992004-07-12 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]658</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]659
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]660</div>
661
662<!-- ======================================================================= -->
663<div class="doc_subsection">
Chris Lattnerdf925ce2004-11-07 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 Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]670<li>None yet</li>
Chris Lattnerdf925ce2004-11-07 01:55:32 +0000[diff] [blame]671</ul>
672
673</div>
674
675<!-- ======================================================================= -->
676<div class="doc_subsection">
Misha Brukman80731b92003-11-22 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 Lattner3d482502003-10-02 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 Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]687problem probably cannot be fixed.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]688
Chris Lattnerc679fbb2003-11-04 20:06:53 +0000[diff] [blame]689<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]690supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]691frontends.</li>
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]692
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]693</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]694
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]695</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]696
Andrew Lenharth2e18c622005-05-03 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 Lenharth8ecaa452005-05-14 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 Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]712</ul>
713
714</div>
715
Duraid Madina9a449002005-05-14 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 Lattnerb62a5f02005-05-15 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]757<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]758<div class="doc_section">
759 <a name="additionalinfo">Additional Information</a>
760</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]761<!-- *********************************************************************** -->
762
Misha Brukman80731b92003-11-22 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 Brukman96158092005-03-30 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 Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]772
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]773<p>If you have any questions or comments about LLVM, please feel free to contact
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]774us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
775lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]776
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]777</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]778
779<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]780
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]781<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]782<address>
Misha Brukman8834af92003-12-21 22:53:21 +0000[diff] [blame]783 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman68aab3b2003-11-22 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 Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]788 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]789 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]790</address>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]791
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]792</body>
793</html>