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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 8a458764d69892b824f760a3308d608d5750abf4 / . / 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<!--_________________________________________________________________________-->
78<div class="doc_subsubsection">New Native Code Generators</div>
79
80<div class="doc_text">
81<p>
82This release includes new native code generators for <a
83href="#alpha-be">Alpha</a>, <a href="#ia64-be">IA-64</a>, and SPARC-V8 (32-bit
84SPARC). These code generators are still beta quality, but are progressing
85rapidly.
86</p>
87</div>
88
89<!--_________________________________________________________________________-->
90<div class="doc_subsubsection">New Instruction Selector Framework</div>
91
92<div class="doc_text">
93<p>This release includes a <a href="CodeGenerator.html#instselect">new framework
94for building instruction selectors</a>, which has long been the hardest part of
95building a new LLVM target. This framework handles a lot of the mundane (but
96easy to get wrong) details of writing the instruction selector, such as
97generating efficient code for <a
98href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting
99small integer types to larger types (e.g. for RISC targets with one size of
100integer registers), expanding 64-bit integer operations for 32-bit hosts, etc.
101Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The
102SPARC backends will be migrated when time permits.
103</p>
104</div>
105
106<!--_________________________________________________________________________-->
107<div class="doc_subsubsection">New Support For Custom Calling Convetions</div>
108
109<div class="doc_text">
110<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">custom and
111target-specific calling conventions</a>. Traditionally, the LLVM code
112generators match the native C calling conventions for a target. This is
113important for compatibility, but is not very flexible. This release allows
114custom calling conventions to be established for functions, and defines three
115target-independent conventions (C call, fast call, and cold call) which may be
116supported by code generators. When possible, the LLVM optimizer promotes C
117functions to use the "fastcc" convention, allowing the use of more efficient
118calling sequences (e.g., parameters are passed in registers in the X86 target).
119</p>
120
121<p>Targets may now also define target-specific calling conventions, allowing
122LLVM to fully support calling convention altering options (e.g. GCC's
123<tt>-mregparm</tt> flag) and well-defined target conventions (e.g. stdcall and
124fastcall on X86).</p>
125</div>
126
127<!--_________________________________________________________________________-->
128<div class="doc_subsubsection">New Support for "Proper Tail Calls"</div>
129
130<div class="doc_text">
131<p>The release now includes support for <a
132href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as
133required to implement languages like Scheme. Tail calls make use of two
134features: custom calling conventions (described above), which allow the code
135generator to emit code for the caller to deallocate its own stack when it
136returns. The second feature is a flag on the <a href="LangRef.html#i_call">call
137instruction</a>, which indicates that the callee does not access the callers
138stack frame (indicating that it is acceptable to deallocate the caller stack
139before invoking the callee). LLVM proper tail calls run on the system stack (as
140do normal calls), supports indirect tail calls, tail calls with arbitrary
141numbers of arguments, tail calls where the callee requires more argument space
142than the caller, etc. The only case not supported are varargs calls, but that
143could be added if desired.
144</p>
145
146<p>In order for a front-end to get guaranteed tail call, it must mark functions
147as "fastcc", mark calls with the 'tail' marker, and follow the call with a
148return of the called value (or void). The optimizer and code generator attempt
149to handle more general cases, but the simple case will always work if the code
150generator supports tail calls. Here is a simple example:</p>
151
152<p><pre>
153fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i>
154 %Y = tail call fastcc int %FP(double 0.0, int %X) ;<i> tail, fastcc</i>
155 ret int %Y
156}
157</pre></p>
158
159<p>In LLVM 1.5, the X86 code generator is the only target that has been enhanced
160to support proper tail calls (other targets will be enhanced in future).
161Further, because this support was added very close to the release, it is
162disabled by default. Pass <tt>-enable-x86-fastcc</tt> to llc to enable it. X86
163support will be enabled by default in the next LLVM release.</p>
164</div>
165
166<!--_________________________________________________________________________-->
167<div class="doc_subsubsection">Other New Features</div>
168
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]169<div class="doc_text">
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]170<ol>
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]171 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattnerda1f03c2005-01-22 18:45:35 +0000[diff] [blame]172 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner74d74cd2004-12-11 06:10:52 +0000[diff] [blame]173 -ipsccp, which is run by default at link-time.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]174 <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data
175 structures use about 30% less memory.</li>
Chris Lattner2e12c742005-02-13 22:27:24 +0000[diff] [blame]176 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattnera5d803e2005-02-14 22:58:38 +0000[diff] [blame]177 href="GettingStartedVS.html">now documented</a>.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]178 <li><a href="GettingStarted.html#config">Configuring LLVM to build a subset
179 of the available targets</a> is now implemented, via the
180 <tt>--enable-targets=</tt> option.</li>
Chris Lattnerd7934542005-02-28 16:52:28 +0000[diff] [blame]181 <li>LLVM can now create native shared libraries with '<tt>llvm-gcc ...
182 -shared -Wl,-native</tt>' (or with <tt>-Wl,-native-cbe</tt>).</li>
Chris Lattnerd03b3bc2005-03-11 06:16:26 +0000[diff] [blame]183 <li>LLVM now supports a new "<a href="LangRef.html#i_prefetch">llvm.prefetch
184 </a>" intrinsic, and llvm-gcc now supports __builtin_prefetch.
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]185 <li>LLVM now supports intrinsics for <a href="LangRef.html#int_count">bit
186 counting</a> and llvm-gcc now implements the GCC
187 <tt>__builtin_popcount</tt>, <tt>__builtin_ctz</tt>, and
188 <tt>__builtin_clz</tt> builtins.</li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]189 <li>LLVM now builds on HP-UX with the HP aCC Compiler.</li>
190 <li>The LLVM X86 backend can now emit Cygwin-compatible .s files.</li>
191 <li>LLVM now includes workarounds in the code generator generator which
192 reduces the likelyhood of <a href="http://llvm.cs.uiuc.edu/PR448">GCC
193 hitting swap during optimized builds</a>.</li>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]194</ol>
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]195</div>
Brian Gaeke6b31beb2004-01-16 21:55:04 +0000[diff] [blame]196
197<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]198<div class="doc_subsection">
199<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattneraab56d42004-05-23 20:42:08 +0000[diff] [blame]200</div>
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]201
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]202<div class="doc_text">
Chris Lattner89ca2b82003-10-27 17:06:39 +0000[diff] [blame]203<ol>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]204<li>The -globalopt pass now promotes non-address-taken static globals that are
205only accessed in main to SSA registers.</li>
206
207<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i
208= 0; &amp;A[i] != &amp;A[100]; ++i) ...</tt>") are optimized better than before,
209which primarily helps iterator-intensive C++ codes.</li>
210
211<li>The code generator now uses information about takes advantage of commutative
212two-address instructions when performing register allocation.</li>
213
214
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]215</ol>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]216</div>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]217
218<!--=========================================================================-->
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]219<div class="doc_subsection">
220<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]221</div>
222
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]223<div class="doc_text">
224
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]225
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]226<p>Bugs fixed in the LLVM Core:</p>
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]227<ol>
Chris Lattnerbfd24682004-12-29 04:39:50 +0000[diff] [blame]228 <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that
229 are partially overwritten by smaller stores</a></li>
Chris Lattnerf79e57e2005-04-19 06:08:04 +0000[diff] [blame]230 <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
231 setcc or setcc in one case</a></li>
Chris Lattner8a458762005-05-15 05:44:51 +0000[diff] [blame^]232 <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
233 parser. LLVM 1.0 bytecode files are still supported. </li>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]234</ol>
235
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]236<p>Code Generator Bugs:</p>
237<ol>
238 <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant
239 expressions (and/or/xor) not implemented</a></li>
240 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
241 respect 'volatile'</a></li>
242</ol>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]243
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]244<p>Bugs in the C/C++ front-end:</p>
Chris Lattnera5099962003-12-06 20:22:41 +0000[diff] [blame]245<ol>
Chris Lattner8de9f232005-01-03 04:20:21 +0000[diff] [blame]246 <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly
247 rejects some constant initializers involving the addresses of array
248 elements</a></li>
Chris Lattnerf832f6a2005-02-11 19:29:52 +0000[diff] [blame]249 <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling
250 anonymous union</a></li>
Chris Lattnerf54e9cb2005-02-14 16:57:55 +0000[diff] [blame]251 <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic
252 initialization where static init will do</a></li>
Chris Lattner4a9dc292005-02-15 05:28:06 +0000[diff] [blame]253 <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset
254 miscalculated for some structure fields following bit fields</a></li>
Chris Lattner5ad907a2005-02-15 07:02:12 +0000[diff] [blame]255 <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes
256 incorrect for short circuit logical operations</a></li>
Chris Lattnerc1f90a92005-02-19 07:29:25 +0000[diff] [blame]257 <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling
258 bitfield &lt;-&gt; aggregate assignment</a></li>
Chris Lattner94f6ac72005-02-19 17:13:20 +0000[diff] [blame]259 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattnerd12b9b22005-02-19 17:17:32 +0000[diff] [blame]260 virtual function thunk with an unnamed argument</a></li>
Chris Lattner290d2292005-02-20 23:31:49 +0000[diff] [blame]261 <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain
262 C99 complex number routines</a></li>
Chris Lattner2a3cdf72005-02-27 19:31:02 +0000[diff] [blame]263 <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement
264 new on an array type</a></li>
Brian Gaekee77c8e72004-08-24 07:43:48 +0000[diff] [blame]265</ol>
266
Chris Lattner80453c92004-05-24 04:50:25 +0000[diff] [blame]267</div>
Reid Spencer8e0262f2004-05-23 17:23:13 +0000[diff] [blame]268
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]269<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]270<div class="doc_section">
271 <a name="portability">Portability and Supported Platforms</a>
272</div>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]273<!-- *********************************************************************** -->
274
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]275<div class="doc_text">
276
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]277<p>LLVM is known to work on the following platforms:</p>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]278
279<ul>
280<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
281 other unix-like systems).</li>
282<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]283<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
284 support is available for native builds with Visual C++).</li>
285<li>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]286<li>Alpha-based machines running Debian GNU/Linux.</li>
287<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner4654bdb2004-06-01 18:22:41 +0000[diff] [blame]288</ul>
289
Brian Gaekeb0fd7612004-05-09 05:28:35 +0000[diff] [blame]290<p>The core LLVM infrastructure uses
291<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
292to the machine and operating system on which it is built. However, minor
293porting may be required to get LLVM to work on new platforms. We welcome your
294portability patches and reports of successful builds or error messages.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]295
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]296</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]297
298<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]299<div class="doc_section">
300 <a name="knownproblems">Known Problems</a>
301</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]302<!-- *********************************************************************** -->
303
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]304<div class="doc_text">
305
306<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]307component. As new problems are discovered, they will be added to these
Chris Lattner5eccca42003-12-12 21:22:16 +0000[diff] [blame]308sections. If you run into a problem, please check the <a
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]309href="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]310there isn't already one.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]311
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]312</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]313
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]314<!-- ======================================================================= -->
315<div class="doc_subsection">
316 <a name="experimental">Experimental features included with this release</a>
317</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]318
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]319<div class="doc_text">
320
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]321<p>The following components of this LLVM release are either untested, known to
322be broken or unreliable, or are in early development. These components should
323not be relied on, and bugs should not be filed against them, but they may be
324useful to some people. In particular, if you would like to work on one of these
325components, please contact us on the llvmdev list.</p>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]326
327<ul>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]328<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner1fe848e2005-01-28 06:13:52 +0000[diff] [blame]329 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]330<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
331 be used to step through programs and inspect the stack.</li>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]332<li>The "iterative scan" register allocator (enabled with
333 <tt>-regalloc=iterativescan</tt>) is not stable.</li>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]334<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerf5ee1702004-03-14 02:03:02 +0000[diff] [blame]335</ul>
336
337</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]338
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]339<!-- ======================================================================= -->
340<div class="doc_subsection">
341 <a name="core">Known problems with the LLVM Core</a>
342</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]343
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]344<div class="doc_text">
345
346<ul>
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]347 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
348 work.</li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]349 <li>The JIT does not use mutexes to protect its internal data structures. As
350 such, execution of a threaded program could cause these data structures to be
351 corrupted.
352 </li>
Reid Spencer4f86f9c2004-11-25 22:38:30 +0000[diff] [blame]353 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
354 mark values live across a setjmp as volatile</a>. This missing feature
355 only affects targets whose setjmp/longjmp libraries do not save and restore
356 the entire register file.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]357</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]358</div>
359
360<!-- ======================================================================= -->
361<div class="doc_subsection">
362 <a name="c-fe">Known problems with the C front-end</a>
363</div>
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]364
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]365<!-- _______________________________________________________________________ -->
Chris Lattnerb40efb32003-12-14 05:03:43 +0000[diff] [blame]366<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]367
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]368<div class="doc_text">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]369<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]370<li>C99 Variable sized arrays do not release stack memory when they go out of
371 scope. Thus, the following program may run out of stack space:
372<pre>
373 for (i = 0; i != 1000000; ++i) {
374 int X[n];
375 foo(X);
376 }
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]377</pre></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]378
Misha Brukman6df9e2c2004-05-12 21:46:05 +0000[diff] [blame]379<li>Initialization of global union variables can only be done <a
Misha Brukman43ee2932004-12-04 00:45:09 +0000[diff] [blame]380href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattnerf580cdc2004-03-16 21:39:04 +0000[diff] [blame]381
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]382</ul>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]383</div>
384
385<!-- _______________________________________________________________________ -->
386<div class="doc_subsubsection">
387 Notes
388</div>
389
390<div class="doc_text">
391
392<ul>
393
394<li>Inline assembly is not yet supported.</li>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]395
396<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]397support for floating point data types of any size other than 32 and 64
398bits.</li>
399
400<li>The following Unix system functionality has not been tested and may not
401work:
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]402 <ol>
403 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
404 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
405 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
406 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
407 - These functions have not been tested.
408 </ol></li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]409
410<li>Although many GCC extensions are supported, some are not. In particular,
411 the following extensions are known to <b>not be</b> supported:
412 <ol>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]413 <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]414 <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>
415 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
416 <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]417 <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]418 <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>
419 <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]420 <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>
421 <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]422 <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]423 <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]424 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]425
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]426 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]427 attribute means that the LLVM compiler ignores the presence of the attribute,
428 but the code should still work. An unsupported attribute is one which is
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]429 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]430 the program.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]431
432 <ol>
433 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
434 Arrays whose length is computed at run time.<br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]435 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]436
437 <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]438
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]439 Declaring that functions have no side effects or that they can never
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]440 return.<br>
441
442 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]443 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
444 <tt>unused</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]445 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
446
John Criswell0b5b5e92004-12-08 20:35:47 +0000[diff] [blame]447 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]448 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
449 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
450
451 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
452 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
453 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]454
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
456 Specifying attributes of variables.<br>
457 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
458 <tt>deprecated</tt>, <tt>transparent_union</tt>,
459 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]460
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]461 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
462 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
463 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]464 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]465
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]466 <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]467 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukmanc4b7bee2003-12-12 04:37:31 +0000[diff] [blame]468 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]469
470 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
471 all target specific attributes.</li>
472
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]473 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
474 Other built-in functions.<br>
475 We support all builtins which have a C language equivalent (e.g.,
476 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
477 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerceebeb62004-06-18 06:26:29 +0000[diff] [blame]478 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
479 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattner7939b782005-05-07 02:21:21 +0000[diff] [blame]480 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
481 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
482 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]483 </ol>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]484
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]485 <p>The following extensions <b>are</b> known to be supported:</p>
486
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]487 <ol>
Chris Lattner7fe97dd2004-03-16 08:54:07 +0000[diff] [blame]488 <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]489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
490 <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]491 <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]492 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
494 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
496 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
497 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
498 <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>
499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
500 <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]501 <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]502 <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]503 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
504or arrays as values.</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]505 <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]506 <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]507 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
508 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
509 <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]510 <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]511 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
512 <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>
513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
514 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
515 <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>
516 <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>
517 <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]518 <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]519 <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>
520 <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]521 </ol></li>
522
523</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]524
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]525<p>If you run into GCC extensions which have not been included in any of these
526lists, please let us know (also including whether or not they work).</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]527
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]528</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]529
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]530<!-- ======================================================================= -->
531<div class="doc_subsection">
532 <a name="c++-fe">Known problems with the C++ front-end</a>
533</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]534
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]535<div class="doc_text">
536
Reid Spencere09ca642004-12-07 08:39:08 +0000[diff] [blame]537<p>For this release, the C++ front-end is considered to be fully
Chris Lattner7506b1d2004-12-07 08:04:13 +0000[diff] [blame]538tested and works for a number of non-trivial programs, including LLVM
539itself.</p>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]540
541</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]542
543<!-- _______________________________________________________________________ -->
Chris Lattner3a51be12004-02-14 04:12:41 +0000[diff] [blame]544<div class="doc_subsubsection">Bugs</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]545
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]546<div class="doc_text">
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]547
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]548<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]549<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]550 front-end</a>.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]551
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]552<li><b>IA-64 specific</b>: The C++ front-end does not use <a
553href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]554In particular, it just stores function pointers instead of function
555descriptors in the vtable. This bug prevents mixing C++ code compiled with
Chris Lattner04db8082004-08-02 20:29:51 +0000[diff] [blame]556LLVM with C++ objects compiled by other C++ compilers.</li>
Chris Lattner7962f712004-07-17 02:04:41 +0000[diff] [blame]557
Chris Lattnerd5713882004-08-02 20:28:44 +0000[diff] [blame]558</ul>
559
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]560</div>
561
562<!-- _______________________________________________________________________ -->
563<div class="doc_subsubsection">
564 Notes
565</div>
566
567<div class="doc_text">
568
569<ul>
Chris Lattnere01fcfb2003-10-27 18:30:37 +0000[diff] [blame]570
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]571<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
572parser is significantly more standards compliant (and picky) than prior GCC
573versions. For more information, see the C++ section of the <a
Chris Lattner9e848092003-12-12 04:25:33 +0000[diff] [blame]574href="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]575
576<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]577 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]578 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswelld000e1d2003-12-18 16:43:17 +0000[diff] [blame]579 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]580 better than most compilers).</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]581
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]582<li>The LLVM C++ front-end follows the <a
583 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
584 This document, which is not Itanium specific, specifies a standard for name
585 mangling, class layout, v-table layout, RTTI formats, and other C++
586 representation issues. Because we use this API, code generated by the LLVM
587 compilers should be binary compatible with machine code generated by other
588 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
589 <i>However</i>, the exception handling mechanism used by LLVM is very
590 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]591 interact correctly</b>. </li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]592
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]593</ul>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]594
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]595</div>
596
597<!-- ======================================================================= -->
598<div class="doc_subsection">
599 <a name="x86-be">Known problems with the X86 back-end</a>
600</div>
601
602<div class="doc_text">
603
604<ul>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]605 <li>None yet</li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]606</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]607
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]608</div>
609
610<!-- ======================================================================= -->
611<div class="doc_subsection">
Misha Brukmanadb1c392004-07-12 16:55:41 +0000[diff] [blame]612 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]613</div>
614
615<div class="doc_text">
616
617<ul>
Misha Brukmanadb1c392004-07-12 16:55:41 +0000[diff] [blame]618<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
619several programs in the LLVM test suite</a></li>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]620</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]621
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]622</div>
623
624<!-- ======================================================================= -->
625<div class="doc_subsection">
Chris Lattnerf32a5f52004-11-07 01:55:32 +0000[diff] [blame]626 <a name="ppc-be">Known problems with the PowerPC back-end</a>
627</div>
628
629<div class="doc_text">
630
631<ul>
John Criswell9321fa82005-05-13 20:28:15 +0000[diff] [blame]632<li>None yet</li>
Chris Lattnerf32a5f52004-11-07 01:55:32 +0000[diff] [blame]633</ul>
634
635</div>
636
637<!-- ======================================================================= -->
638<div class="doc_subsection">
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]639 <a name="c-be">Known problems with the C back-end</a>
640</div>
641
642<div class="doc_text">
643
644<ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]645
646<li>The C back-end produces code that violates the ANSI C Type-Based Alias
647Analysis rules. As such, special options may be necessary to compile the code
648(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]649problem probably cannot be fixed.</li>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]650
Chris Lattner2855ecd2003-11-04 20:06:53 +0000[diff] [blame]651<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]652supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]653frontends.</li>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame]654
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]655</ul>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]656
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]657</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]658
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]659<!-- ======================================================================= -->
660<div class="doc_subsection">
661 <a name="alpha-be">Known problems with the Alpha back-end</a>
662</div>
663
664<div class="doc_text">
665
666<ul>
667
668<li>On 21164s, some rare FP arithmatic sequences which may trap do not have the appropriate nops inserted to ensure restartability.</li>
669
670<li>Vararg functions are not supported.</li>
671
Andrew Lenharth01f40b32005-05-14 17:43:00 +0000[diff] [blame]672<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>
673
Andrew Lenharth30a1f8f2005-05-03 16:59:09 +0000[diff] [blame]674</ul>
675
676</div>
677
Duraid Madina2e36d6e2005-05-14 05:48:13 +0000[diff] [blame]678<!-- ======================================================================= -->
679<div class="doc_subsection">
680 <a name="ia64-be">Known problems with the IA64 back-end</a>
681</div>
682
683<div class="doc_text">
684
685<ul>
686
687<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
688made where the argument is not 16-byte aligned, as required on IA64. (Strictly
689speaking this is not a bug in the IA64 back-end; it will also be encountered
690when building C++ programs using the C back-end.)</li>
691
692<li>There are a few ABI violations which will lead to problems
693when mixing LLVM output with code built with other compilers,
694particularly for C++ and floating-point programs.</li>
695
696<li>Vararg functions are not supported.</li>
697
698</ul>
699
700</div>
701
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]702<!-- *********************************************************************** -->
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]703<div class="doc_section">
704 <a name="additionalinfo">Additional Information</a>
705</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]706<!-- *********************************************************************** -->
707
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]708<div class="doc_text">
709
710<p>A wide variety of additional information is available on the LLVM web page,
Misha Brukman109d9e82005-03-30 19:14:24 +0000[diff] [blame]711including <a href="http://llvm.cs.uiuc.edu/docs/#maillist">mailing lists</a> and
712<a href="http://llvm.cs.uiuc.edu/pubs/">publications describing algorithms and
713components implemented in LLVM</a>. The web page also contains versions of the
714API documentation which is up-to-date with the CVS version of the source code.
715You can access versions of these documents specific to this release by going
716into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]717
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]718<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]719us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
720lists</a>.</p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]721
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]722</div>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]723
724<!-- *********************************************************************** -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]725
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]726<hr>
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]727<address>
Misha Brukman38847d52003-12-21 22:53:21 +0000[diff] [blame]728 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]729 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
730 <a href="http://validator.w3.org/check/referer"><img
731 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
732
Misha Brukmane0c891c2003-11-22 01:00:11 +0000[diff] [blame]733 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]734 Last modified: $Date$
Misha Brukman2061e892003-11-22 01:23:39 +0000[diff] [blame]735</address>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]736
Misha Brukman500bc302003-11-22 00:38:41 +0000[diff] [blame]737</body>
738</html>