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4<head>
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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<!--_________________________________________________________________________-->
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 Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]169<div class="doc_text">
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]170<ol>
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]171 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattner64d9d2b2005-01-22 18:45:35 +0000[diff] [blame]172 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]173 -ipsccp, which is run by default at link-time.</li>
Chris Lattner406bddf2005-05-15 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 Lattnere14babd2005-02-13 22:27:24 +0000[diff] [blame]176 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattnerbe895ed2005-02-14 22:58:38 +0000[diff] [blame]177 href="GettingStartedVS.html">now documented</a>.</li>
Chris Lattner406bddf2005-05-15 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 Lattner81c1dd22005-02-28 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 Lattnerdb302f82005-03-11 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 Lattnerb34b2732005-05-07 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 Lattner406bddf2005-05-15 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 Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]194</ol>
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]195</div>
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]196
197<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]198<div class="doc_subsection">
199<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattner23257062004-05-23 20:42:08 +0000[diff] [blame]200</div>
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]201
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]202<div class="doc_text">
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]203<ol>
Chris Lattner406bddf2005-05-15 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
Reid Spencerea776852005-05-15 06:05:11 +0000[diff] [blame^]214<li>A new pass has been added to gccas to simplify well-known library calls. The
215pass will short circuit calls to many of the string, memory, and printf type
216functions or replace the calls with simpler/faster calls, where possible given
217information known statically about the arguments to the call. To use the
218pass, specify <tt>-simplify-libcalls</tt> to the <tt>opt</tt> tool.</li>
219
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]220
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]221</ol>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]222</div>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]223
224<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]225<div class="doc_subsection">
226<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]227</div>
228
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]229<div class="doc_text">
230
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]231
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]232<p>Bugs fixed in the LLVM Core:</p>
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]233<ol>
Chris Lattnerb5c253a2004-12-29 04:39:50 +0000[diff] [blame]234 <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that
235 are partially overwritten by smaller stores</a></li>
Chris Lattner181c8182005-04-19 06:08:04 +0000[diff] [blame]236 <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
237 setcc or setcc in one case</a></li>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]238 <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
239 parser. LLVM 1.0 bytecode files are still supported. </li>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]240</ol>
241
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]242<p>Code Generator Bugs:</p>
243<ol>
244 <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant
245 expressions (and/or/xor) not implemented</a></li>
246 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
247 respect 'volatile'</a></li>
248</ol>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]249
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]250<p>Bugs in the C/C++ front-end:</p>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]251<ol>
Chris Lattnere1329f42005-01-03 04:20:21 +0000[diff] [blame]252 <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly
253 rejects some constant initializers involving the addresses of array
254 elements</a></li>
Chris Lattner2a38aea2005-02-11 19:29:52 +0000[diff] [blame]255 <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling
256 anonymous union</a></li>
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]257 <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic
258 initialization where static init will do</a></li>
Chris Lattner1f031b22005-02-15 05:28:06 +0000[diff] [blame]259 <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset
260 miscalculated for some structure fields following bit fields</a></li>
Chris Lattner385a4732005-02-15 07:02:12 +0000[diff] [blame]261 <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes
262 incorrect for short circuit logical operations</a></li>
Chris Lattner48c23142005-02-19 07:29:25 +0000[diff] [blame]263 <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling
264 bitfield &lt;-&gt; aggregate assignment</a></li>
Chris Lattner6a3ae642005-02-19 17:13:20 +0000[diff] [blame]265 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattner3d6194f2005-02-19 17:17:32 +0000[diff] [blame]266 virtual function thunk with an unnamed argument</a></li>
Chris Lattner3a8f68e2005-02-20 23:31:49 +0000[diff] [blame]267 <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain
268 C99 complex number routines</a></li>
Chris Lattnerc6e33802005-02-27 19:31:02 +0000[diff] [blame]269 <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement
270 new on an array type</a></li>
Brian Gaeke730d8d62004-08-24 07:43:48 +0000[diff] [blame]271</ol>
272
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]273</div>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]274
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]275<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]276<div class="doc_section">
277 <a name="portability">Portability and Supported Platforms</a>
278</div>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]279<!-- *********************************************************************** -->
280
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]281<div class="doc_text">
282
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]283<p>LLVM is known to work on the following platforms:</p>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]284
285<ul>
286<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
287 other unix-like systems).</li>
288<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]289<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
290 support is available for native builds with Visual C++).</li>
291<li>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]292<li>Alpha-based machines running Debian GNU/Linux.</li>
293<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]294</ul>
295
Brian Gaekee3e557e2004-05-09 05:28:35 +0000[diff] [blame]296<p>The core LLVM infrastructure uses
297<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
298to the machine and operating system on which it is built. However, minor
299porting may be required to get LLVM to work on new platforms. We welcome your
300portability patches and reports of successful builds or error messages.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]301
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]302</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]303
304<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]305<div class="doc_section">
306 <a name="knownproblems">Known Problems</a>
307</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]308<!-- *********************************************************************** -->
309
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]310<div class="doc_text">
311
312<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]313component. As new problems are discovered, they will be added to these
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]314sections. If you run into a problem, please check the <a
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]315href="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]316there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]317
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]318</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]319
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]320<!-- ======================================================================= -->
321<div class="doc_subsection">
322 <a name="experimental">Experimental features included with this release</a>
323</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]324
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]325<div class="doc_text">
326
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]327<p>The following components of this LLVM release are either untested, known to
328be broken or unreliable, or are in early development. These components should
329not be relied on, and bugs should not be filed against them, but they may be
330useful to some people. In particular, if you would like to work on one of these
331components, please contact us on the llvmdev list.</p>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]332
333<ul>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]334<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner38389b12005-01-28 06:13:52 +0000[diff] [blame]335 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]336<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
337 be used to step through programs and inspect the stack.</li>
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]338<li>The "iterative scan" register allocator (enabled with
339 <tt>-regalloc=iterativescan</tt>) is not stable.</li>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]340<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]341</ul>
342
343</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]344
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]345<!-- ======================================================================= -->
346<div class="doc_subsection">
347 <a name="core">Known problems with the LLVM Core</a>
348</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]349
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]350<div class="doc_text">
351
352<ul>
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]353 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
354 work.</li>
Reid Spencer493d9c22004-11-25 22:38:30 +0000[diff] [blame]355 <li>The JIT does not use mutexes to protect its internal data structures. As
356 such, execution of a threaded program could cause these data structures to be
357 corrupted.
358 </li>
Reid Spencer493d9c22004-11-25 22:38:30 +0000[diff] [blame]359 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
360 mark values live across a setjmp as volatile</a>. This missing feature
361 only affects targets whose setjmp/longjmp libraries do not save and restore
362 the entire register file.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]363</ul>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]364</div>
365
366<!-- ======================================================================= -->
367<div class="doc_subsection">
368 <a name="c-fe">Known problems with the C front-end</a>
369</div>
Chris Lattner178f3db2003-10-02 05:07:23 +0000[diff] [blame]370
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]371<!-- _______________________________________________________________________ -->
Chris Lattner5a8a7282003-12-14 05:03:43 +0000[diff] [blame]372<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]373
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]374<div class="doc_text">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]375<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]376<li>C99 Variable sized arrays do not release stack memory when they go out of
377 scope. Thus, the following program may run out of stack space:
378<pre>
379 for (i = 0; i != 1000000; ++i) {
380 int X[n];
381 foo(X);
382 }
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]383</pre></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]384
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]385<li>Initialization of global union variables can only be done <a
Misha Brukman68ef9a92004-12-04 00:45:09 +0000[diff] [blame]386href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattner1ab58dd2004-03-16 21:39:04 +0000[diff] [blame]387
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]388</ul>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]389</div>
390
391<!-- _______________________________________________________________________ -->
392<div class="doc_subsubsection">
393 Notes
394</div>
395
396<div class="doc_text">
397
398<ul>
399
400<li>Inline assembly is not yet supported.</li>
Chris Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]401
402<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]403support for floating point data types of any size other than 32 and 64
404bits.</li>
405
406<li>The following Unix system functionality has not been tested and may not
407work:
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]408 <ol>
409 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
410 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
411 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
412 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
413 - These functions have not been tested.
414 </ol></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]415
416<li>Although many GCC extensions are supported, some are not. In particular,
417 the following extensions are known to <b>not be</b> supported:
418 <ol>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]419 <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]420 <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>
421 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
422 <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]423 <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]424 <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>
425 <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]426 <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>
427 <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]428 <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]429 <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]430 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]431
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]432 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]433 attribute means that the LLVM compiler ignores the presence of the attribute,
434 but the code should still work. An unsupported attribute is one which is
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]435 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]436 the program.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]437
438 <ol>
439 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
440 Arrays whose length is computed at run time.<br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]441 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]442
443 <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]444
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]445 Declaring that functions have no side effects or that they can never
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]446 return.<br>
447
448 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]449 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
450 <tt>unused</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]451 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
452
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]453 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]454 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
455 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
456
457 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
458 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
459 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]460
461 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
462 Specifying attributes of variables.<br>
463 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
464 <tt>deprecated</tt>, <tt>transparent_union</tt>,
465 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]466
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]467 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
468 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
469 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]470 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]471
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]472 <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]473 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]474 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]475
476 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
477 all target specific attributes.</li>
478
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]479 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
480 Other built-in functions.<br>
481 We support all builtins which have a C language equivalent (e.g.,
482 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
483 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerb7c4bac2004-06-18 06:26:29 +0000[diff] [blame]484 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
485 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattnerb34b2732005-05-07 02:21:21 +0000[diff] [blame]486 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
487 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
488 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]489 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]490
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]491 <p>The following extensions <b>are</b> known to be supported:</p>
492
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]493 <ol>
Chris Lattnerd3dc8502004-03-16 08:54:07 +0000[diff] [blame]494 <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]495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
496 <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]497 <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]498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
500 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
501 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
502 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
503 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
504 <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>
505 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
506 <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]507 <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]508 <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]509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
510or arrays as values.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]511 <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]512 <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]513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
514 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
515 <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]516 <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]517 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
518 <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>
519 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
520 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
521 <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>
522 <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>
523 <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]524 <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]525 <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>
526 <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]527 </ol></li>
528
529</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]530
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]531<p>If you run into GCC extensions which have not been included in any of these
532lists, please let us know (also including whether or not they work).</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]533
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]534</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]535
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]536<!-- ======================================================================= -->
537<div class="doc_subsection">
538 <a name="c++-fe">Known problems with the C++ front-end</a>
539</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]540
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]541<div class="doc_text">
542
Reid Spencer55684c32004-12-07 08:39:08 +0000[diff] [blame]543<p>For this release, the C++ front-end is considered to be fully
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]544tested and works for a number of non-trivial programs, including LLVM
545itself.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]546
547</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]548
549<!-- _______________________________________________________________________ -->
Chris Lattner141ebb62004-02-14 04:12:41 +0000[diff] [blame]550<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]551
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]552<div class="doc_text">
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]553
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]554<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]555<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]556 front-end</a>.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]557
Chris Lattner5cd40922004-08-02 20:28:44 +0000[diff] [blame]558<li><b>IA-64 specific</b>: The C++ front-end does not use <a
559href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]560In particular, it just stores function pointers instead of function
561descriptors in the vtable. This bug prevents mixing C++ code compiled with
Chris Lattner2fd93492004-08-02 20:29:51 +0000[diff] [blame]562LLVM with C++ objects compiled by other C++ compilers.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]563
Chris Lattner5cd40922004-08-02 20:28:44 +0000[diff] [blame]564</ul>
565
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]566</div>
567
568<!-- _______________________________________________________________________ -->
569<div class="doc_subsubsection">
570 Notes
571</div>
572
573<div class="doc_text">
574
575<ul>
Chris Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]576
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]577<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
578parser is significantly more standards compliant (and picky) than prior GCC
579versions. For more information, see the C++ section of the <a
Chris Lattnere76e9ab2003-12-12 04:25:33 +0000[diff] [blame]580href="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]581
582<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]583 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]584 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]585 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]586 better than most compilers).</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]587
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]588<li>The LLVM C++ front-end follows the <a
589 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
590 This document, which is not Itanium specific, specifies a standard for name
591 mangling, class layout, v-table layout, RTTI formats, and other C++
592 representation issues. Because we use this API, code generated by the LLVM
593 compilers should be binary compatible with machine code generated by other
594 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
595 <i>However</i>, the exception handling mechanism used by LLVM is very
596 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]597 interact correctly</b>. </li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]598
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]599</ul>
Chris Lattner46ecf612003-10-07 22:14:37 +0000[diff] [blame]600
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]601</div>
602
603<!-- ======================================================================= -->
604<div class="doc_subsection">
605 <a name="x86-be">Known problems with the X86 back-end</a>
606</div>
607
608<div class="doc_text">
609
610<ul>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]611 <li>None yet</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]612</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]613
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]614</div>
615
616<!-- ======================================================================= -->
617<div class="doc_subsection">
Misha Brukmana516e992004-07-12 16:55:41 +0000[diff] [blame]618 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]619</div>
620
621<div class="doc_text">
622
623<ul>
Misha Brukmana516e992004-07-12 16:55:41 +0000[diff] [blame]624<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
625several programs in the LLVM test suite</a></li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]626</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]627
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]628</div>
629
630<!-- ======================================================================= -->
631<div class="doc_subsection">
Chris Lattnerdf925ce2004-11-07 01:55:32 +0000[diff] [blame]632 <a name="ppc-be">Known problems with the PowerPC back-end</a>
633</div>
634
635<div class="doc_text">
636
637<ul>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]638<li>None yet</li>
Chris Lattnerdf925ce2004-11-07 01:55:32 +0000[diff] [blame]639</ul>
640
641</div>
642
643<!-- ======================================================================= -->
644<div class="doc_subsection">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]645 <a name="c-be">Known problems with the C back-end</a>
646</div>
647
648<div class="doc_text">
649
650<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]651
652<li>The C back-end produces code that violates the ANSI C Type-Based Alias
653Analysis rules. As such, special options may be necessary to compile the code
654(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]655problem probably cannot be fixed.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]656
Chris Lattnerc679fbb2003-11-04 20:06:53 +0000[diff] [blame]657<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]658supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]659frontends.</li>
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]660
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]661</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]662
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]663</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]664
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]665<!-- ======================================================================= -->
666<div class="doc_subsection">
667 <a name="alpha-be">Known problems with the Alpha back-end</a>
668</div>
669
670<div class="doc_text">
671
672<ul>
673
674<li>On 21164s, some rare FP arithmatic sequences which may trap do not have the appropriate nops inserted to ensure restartability.</li>
675
676<li>Vararg functions are not supported.</li>
677
Andrew Lenharth8ecaa452005-05-14 17:43:00 +0000[diff] [blame]678<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>
679
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]680</ul>
681
682</div>
683
Duraid Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]684<!-- ======================================================================= -->
685<div class="doc_subsection">
686 <a name="ia64-be">Known problems with the IA64 back-end</a>
687</div>
688
689<div class="doc_text">
690
691<ul>
692
693<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
694made where the argument is not 16-byte aligned, as required on IA64. (Strictly
695speaking this is not a bug in the IA64 back-end; it will also be encountered
696when building C++ programs using the C back-end.)</li>
697
698<li>There are a few ABI violations which will lead to problems
699when mixing LLVM output with code built with other compilers,
700particularly for C++ and floating-point programs.</li>
701
702<li>Vararg functions are not supported.</li>
703
704</ul>
705
706</div>
707
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]708<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]709<div class="doc_section">
710 <a name="additionalinfo">Additional Information</a>
711</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]712<!-- *********************************************************************** -->
713
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]714<div class="doc_text">
715
716<p>A wide variety of additional information is available on the LLVM web page,
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]717including <a href="http://llvm.cs.uiuc.edu/docs/#maillist">mailing lists</a> and
718<a href="http://llvm.cs.uiuc.edu/pubs/">publications describing algorithms and
719components implemented in LLVM</a>. The web page also contains versions of the
720API documentation which is up-to-date with the CVS version of the source code.
721You can access versions of these documents specific to this release by going
722into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]723
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]724<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]725us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
726lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]727
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]728</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]729
730<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]731
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]732<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]733<address>
Misha Brukman8834af92003-12-21 22:53:21 +0000[diff] [blame]734 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]735 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
736 <a href="http://validator.w3.org/check/referer"><img
737 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
738
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]739 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]740 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]741</address>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]742
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]743</body>
744</html>