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gerrit-public.fairphone.software / toolchain / llvm-project / 683a847c2672c11d1206c5f287f44bb1bea77c53 / . / llvm / docs / ReleaseNotes.html
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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 Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]65<p>LLVM 1.5 is known to correctly compile a wide range of C and C++ programs,
66includes bug fixes for those problems found since the 1.4 release, and includes
67a large number of new features and enhancements, described below.</p>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]68
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]69</div>
70
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]71<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]72<div class="doc_subsection">
73<a name="newfeatures">New Features in LLVM 1.5</a>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]74</div>
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]75
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]76<!--_________________________________________________________________________-->
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]77<div class="doc_subsubsection"><a name="newcg">New Native Code
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]78Generators</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]79
80<div class="doc_text">
81<p>
82This release includes new native code generators for <a
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]83href="#alpha-be">Alpha</a>, <a href="#ia64-be">IA-64</a>, and <a
84href="#sparcv8">SPARC-V8</a> (32-bit SPARC). These code generators are still
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]85beta quality, but are progressing rapidly. The Alpha backend is implemented
86with an eye towards being compatible with the widely used SimpleScalar
87simulator.
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]88</p>
89</div>
90
91<!--_________________________________________________________________________-->
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]92<div class="doc_subsubsection"><a name="selectiondag">New Instruction
93Selector Framework</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]94
95<div class="doc_text">
96<p>This release includes a <a href="CodeGenerator.html#instselect">new framework
97for building instruction selectors</a>, which has long been the hardest part of
98building a new LLVM target. This framework handles a lot of the mundane (but
99easy to get wrong) details of writing the instruction selector, such as
100generating efficient code for <a
101href="LangRef.html#i_getelementptr">getelementptr</a> instructions, promoting
102small integer types to larger types (e.g. for RISC targets with one size of
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]103integer registers), expanding 64-bit integer operations for 32-bit targets, etc.
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]104Currently, the X86, PowerPC, Alpha, and IA-64 backends use this framework. The
105SPARC backends will be migrated when time permits.
106</p>
107</div>
108
109<!--_________________________________________________________________________-->
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]110<div class="doc_subsubsection"><a name="customccs">New Support for Per-Function
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]111Calling Conventions</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]112
113<div class="doc_text">
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]114<p>LLVM 1.5 adds supports for <a href="LangRef.html#callingconv">per-function
115calling conventions</a>. Traditionally, the LLVM code generators match the
116native C calling conventions for a target. This is important for compatibility,
117but is not very flexible. This release allows custom calling conventions to be
118established for functions, and defines three target-independent conventions (<a
119href="LangRef.html#callingconv">C call, fast call, and cold call</a>) which may
120be supported by code generators. When possible, the LLVM optimizer promotes C
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]121functions to use the "fastcc" convention, allowing the use of more efficient
122calling sequences (e.g., parameters are passed in registers in the X86 target).
123</p>
124
125<p>Targets may now also define target-specific calling conventions, allowing
126LLVM to fully support calling convention altering options (e.g. GCC's
127<tt>-mregparm</tt> flag) and well-defined target conventions (e.g. stdcall and
128fastcall on X86).</p>
129</div>
130
131<!--_________________________________________________________________________-->
Chris Lattner8563e392005-05-15 15:33:21 +0000[diff] [blame]132<div class="doc_subsubsection"><a name="tailcalls">New Support for
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]133Proper Tail Calls</a></div>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]134
135<div class="doc_text">
136<p>The release now includes support for <a
137href="http://doi.acm.org/10.1145/277650.277719">proper tail calls</a>, as
138required to implement languages like Scheme. Tail calls make use of two
139features: custom calling conventions (described above), which allow the code
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]140generator to use a convention where the caller deallocates its stack before it
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]141returns. The second feature is a flag on the <a href="LangRef.html#i_call">call
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]142instruction</a>, which indicates that the callee does not access the caller's
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]143stack frame (indicating that it is acceptable to deallocate the caller stack
144before invoking the callee). LLVM proper tail calls run on the system stack (as
145do normal calls), supports indirect tail calls, tail calls with arbitrary
146numbers of arguments, tail calls where the callee requires more argument space
147than the caller, etc. The only case not supported are varargs calls, but that
148could be added if desired.
149</p>
150
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]151<p>In order for a front-end to get a guaranteed tail call, it must mark
152functions as "fastcc", mark calls with the 'tail' marker, and follow the call
153with a return of the called value (or void). The optimizer and code generator
154attempt to handle more general cases, but the simple case will always work if
155the code generator supports tail calls. Here is an example:</p>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]156
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]157<pre>
Chris Lattner55f987b2005-05-15 06:07:40 +0000[diff] [blame]158 fastcc int %bar(int %X, int(double, int)* %FP) { ;<i> fastcc</i>
159 %Y = tail call fastcc int %FP(double 0.0, int %X) ;<i> tail, fastcc</i>
160 ret int %Y
161 }
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]162</pre>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]163
164<p>In LLVM 1.5, the X86 code generator is the only target that has been enhanced
165to support proper tail calls (other targets will be enhanced in future).
166Further, because this support was added very close to the release, it is
Chris Lattner55f987b2005-05-15 06:07:40 +0000[diff] [blame]167disabled by default. Pass <tt>-enable-x86-fastcc</tt> to llc to enable it (this
168will be enabled by default in the next release). The example above compiles to:
169</p>
170
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]171<pre>
Chris Lattner55f987b2005-05-15 06:07:40 +0000[diff] [blame]172 bar:
173 sub ESP, 8 # Callee uses more space than the caller
174 mov ECX, DWORD PTR [ESP + 8] # Get the old return address
175 mov DWORD PTR [ESP + 4], 0 # First half of 0.0
176 mov DWORD PTR [ESP + 8], 0 # Second half of 0.0
177 mov DWORD PTR [ESP], ECX # Put the return address where it belongs
178 jmp EDX # Tail call "FP"
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]179</pre>
Chris Lattner55f987b2005-05-15 06:07:40 +0000[diff] [blame]180
181<p>
182With fastcc on X86, the first two integer arguments are passed in EAX/EDX, the
183callee pops its arguments off the stack, and the argument area is always a
184multiple of 8 bytes in size.
185</p>
186
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]187</div>
188
189<!--_________________________________________________________________________-->
190<div class="doc_subsubsection">Other New Features</div>
191
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]192<div class="doc_text">
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]193<ol>
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]194 <li>LLVM now includes an <a href="http://llvm.cs.uiuc.edu/PR415">
Chris Lattner64d9d2b2005-01-22 18:45:35 +0000[diff] [blame]195 Interprocedural Sparse Conditional Constant Propagation</a> pass, named
Chris Lattner7bf2e542004-12-11 06:10:52 +0000[diff] [blame]196 -ipsccp, which is run by default at link-time.</li>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]197 <li>LLVM 1.5 is now about 15% faster than LLVM 1.4 and its core data
198 structures use about 30% less memory.</li>
Chris Lattnere14babd2005-02-13 22:27:24 +0000[diff] [blame]199 <li>Support for Microsoft Visual Studio is improved, and <a
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]200 href="GettingStartedVS.html">now documented</a>. Most LLVM tools build
201 natively with Visual C++ now.</li>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]202 <li><a href="GettingStarted.html#config">Configuring LLVM to build a subset
203 of the available targets</a> is now implemented, via the
204 <tt>--enable-targets=</tt> option.</li>
Chris Lattner81c1dd22005-02-28 16:52:28 +0000[diff] [blame]205 <li>LLVM can now create native shared libraries with '<tt>llvm-gcc ...
206 -shared -Wl,-native</tt>' (or with <tt>-Wl,-native-cbe</tt>).</li>
Chris Lattnerdb302f82005-03-11 06:16:26 +0000[diff] [blame]207 <li>LLVM now supports a new "<a href="LangRef.html#i_prefetch">llvm.prefetch
208 </a>" intrinsic, and llvm-gcc now supports __builtin_prefetch.
Chris Lattnerb34b2732005-05-07 02:21:21 +0000[diff] [blame]209 <li>LLVM now supports intrinsics for <a href="LangRef.html#int_count">bit
210 counting</a> and llvm-gcc now implements the GCC
211 <tt>__builtin_popcount</tt>, <tt>__builtin_ctz</tt>, and
212 <tt>__builtin_clz</tt> builtins.</li>
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]213 <li>LLVM now mostly builds on HP-UX with the HP aCC Compiler.</li>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]214 <li>The LLVM X86 backend can now emit Cygwin-compatible .s files.</li>
215 <li>LLVM now includes workarounds in the code generator generator which
216 reduces the likelyhood of <a href="http://llvm.cs.uiuc.edu/PR448">GCC
217 hitting swap during optimized builds</a>.</li>
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]218 <li>The <a href="http://llvm.cs.uiuc.edu/ProjectsWithLLVM/#llvmtv">LLVM
219 Transformation Visualizer</a> (llvm-tv) project has been updated to
220 work with LLVM CVS.</li>
221 <li>Nightly tester output is now archived on the <a
222 href="http://mail.cs.uiuc.edu/pipermail/llvm-testresults/">
223 llvm-testresults</a> mailing list.</li>
224
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]225</ol>
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]226</div>
Brian Gaeke8b05e4f2004-01-16 21:55:04 +0000[diff] [blame]227
228<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]229<div class="doc_subsection">
230<a name="codequality">Code Quality Improvements in LLVM 1.5</a>
Chris Lattner23257062004-05-23 20:42:08 +0000[diff] [blame]231</div>
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]232
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]233<div class="doc_text">
Chris Lattner639579c2003-10-27 17:06:39 +0000[diff] [blame]234<ol>
Chris Lattner17b2e482005-05-15 06:09:55 +0000[diff] [blame]235<li>The new -simplify-libcalls pass improves code generated for well-known
236library calls. The pass optimizes calls to many of the string, memory, and
237standard I/O functions (e.g. replace the calls with simpler/faster calls) when
238possible, given information known statically about the arguments to the call.
239</li>
240
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]241<li>The -globalopt pass now promotes non-address-taken static globals that are
242only accessed in main to SSA registers.</li>
243
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]244<li>Loops with trip counts based on array pointer comparisons (e.g. "<tt>for (i
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]245= 0; &amp;A[i] != &amp;A[n]; ++i) ...</tt>") are optimized better than before,
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]246which primarily helps iterator-intensive C++ codes.</li>
247
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]248<li>The optimizer now eliminates simple cases where redundant conditions exist
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]249 between neighboring blocks.</li>
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]250
251<li>The reassociation pass (which turns (1+X+3) into (X+1+3) among other
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]252things), is more aggressive and intelligent.</li>
253
254<li>The -prune-eh pass now detects no-return functions in addition to the
255 no-unwind functions it did before.</li>
256
257<li>The -globalsmodref alias analysis generates more precise results in some
258 cases.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]259</ol>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]260</div>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]261
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]262
263<!--=========================================================================-->
264<div class="doc_subsection">
265<a name="codequality">Code Generator Improvements in LLVM 1.5</a>
266</div>
267
268<div class="doc_text">
269<ol>
270<li>The code generator now can provide and use information about commutative
271 two-address instructions when performing register allocation.</li>
272
273<li>The code generator now tracks function live-in registers explicitly,
274 instead of requiring the target to generate 'implicit defs' at the
275 entry to a function.</li>
276
277<li>The code generator can lower integer division by a constant to
278 multiplication by a magic constant and multiplication by a constant into
279 shift/add sequences.</li>
280
281<li>The code generator compiles fabs/fneg/sin/cos/sqrt to assembly instructions
282 when possible.</li>
283
284<li>The PowerPC backend generates better code in many cases, making use of
285 FMA instructions and the recording ("dot") forms of various PowerPC
286 instructions.</li>
287</ol>
288</div>
289
290
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]291<!--=========================================================================-->
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]292<div class="doc_subsection">
293<a name="bugfix">Significant Bugs Fixed in LLVM 1.5</a>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]294</div>
295
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]296<div class="doc_text">
297
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]298
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]299<p>Bugs fixed in the LLVM Core:</p>
Chris Lattnere7525b52003-10-07 21:38:31 +0000[diff] [blame]300<ol>
Chris Lattnerb5c253a2004-12-29 04:39:50 +0000[diff] [blame]301 <li><a href="http://llvm.cs.uiuc.edu/PR491">[dse] DSE deletes stores that
302 are partially overwritten by smaller stores</a></li>
Chris Lattner181c8182005-04-19 06:08:04 +0000[diff] [blame]303 <li><a href="http://llvm.cs.uiuc.edu/PR548">[instcombine] miscompilation of
304 setcc or setcc in one case</a></li>
Chris Lattner406bddf2005-05-15 05:44:51 +0000[diff] [blame]305 <li>Transition code for LLVM 1.0 style varargs was removed from the .ll file
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]306 parser. LLVM 1.0 bytecode files are still supported. </li>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]307</ol>
308
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]309<p>Code Generator Bugs:</p>
310<ol>
311 <li><a href="http://llvm.cs.uiuc.edu/PR490">[cbackend] Logical constant
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]312 expressions (and/or/xor) not implemented</a>.</li>
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]313 <li><a href="http://llvm.cs.uiuc.edu/PR511">[cbackend] C backend does not
Chris Lattnera3ea6442005-05-16 06:58:39 +0000[diff] [blame]314 respect 'volatile'</a>.</li>
315 <li>The JIT sometimes miscompiled globals and constant pool entries for
316 64-bit integer constants on 32-bit hosts.</li>
Chris Lattner7e1f2622005-05-16 16:56:09 +0000[diff] [blame]317 <li>The C backend should no longer produce code that crashes ICC 8.1.</li>
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]318</ol>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]319
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]320<p>Bugs in the C/C++ front-end:</p>
Chris Lattnerba7bd472003-12-06 20:22:41 +0000[diff] [blame]321<ol>
Chris Lattnere1329f42005-01-03 04:20:21 +0000[diff] [blame]322 <li><a href="http://llvm.cs.uiuc.edu/PR487">[llvmgcc] llvm-gcc incorrectly
323 rejects some constant initializers involving the addresses of array
324 elements</a></li>
Chris Lattner2a38aea2005-02-11 19:29:52 +0000[diff] [blame]325 <li><a href="http://llvm.cs.uiuc.edu/PR501">[llvm-g++] Crash compiling
326 anonymous union</a></li>
Chris Lattner1c75b252005-02-14 16:57:55 +0000[diff] [blame]327 <li><a href="http://llvm.cs.uiuc.edu/PR509">[llvm-g++] Do not use dynamic
328 initialization where static init will do</a></li>
Chris Lattner1f031b22005-02-15 05:28:06 +0000[diff] [blame]329 <li><a href="http://llvm.cs.uiuc.edu/PR510">[llvmgcc] Field offset
330 miscalculated for some structure fields following bit fields</a></li>
Chris Lattner385a4732005-02-15 07:02:12 +0000[diff] [blame]331 <li><a href="http://llvm.cs.uiuc.edu/PR513">[llvm-g++] Temporary lifetimes
332 incorrect for short circuit logical operations</a></li>
Chris Lattner48c23142005-02-19 07:29:25 +0000[diff] [blame]333 <li><a href="http://llvm.cs.uiuc.edu/PR517">[llvm-gcc] Crash compiling
334 bitfield &lt;-&gt; aggregate assignment</a></li>
Chris Lattner6a3ae642005-02-19 17:13:20 +0000[diff] [blame]335 <li><a href="http://llvm.cs.uiuc.edu/PR520">[llvm-g++] Error compiling
Chris Lattner3d6194f2005-02-19 17:17:32 +0000[diff] [blame]336 virtual function thunk with an unnamed argument</a></li>
Chris Lattner3a8f68e2005-02-20 23:31:49 +0000[diff] [blame]337 <li><a href="http://llvm.cs.uiuc.edu/PR522">[llvm-gcc] Crash on certain
338 C99 complex number routines</a></li>
Chris Lattnerc6e33802005-02-27 19:31:02 +0000[diff] [blame]339 <li><a href="http://llvm.cs.uiuc.edu/PR529">[llvm-g++] Crash using placement
340 new on an array type</a></li>
Brian Gaeke730d8d62004-08-24 07:43:48 +0000[diff] [blame]341</ol>
342
Chris Lattner21a90402004-05-24 04:50:25 +0000[diff] [blame]343</div>
Reid Spencer3e58f582004-05-23 17:23:13 +0000[diff] [blame]344
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]345<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]346<div class="doc_section">
347 <a name="portability">Portability and Supported Platforms</a>
348</div>
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]349<!-- *********************************************************************** -->
350
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]351<div class="doc_text">
352
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]353<p>LLVM is known to work on the following platforms:</p>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]354
355<ul>
356<li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
357 other unix-like systems).</li>
358<li>Sun UltraSPARC workstations running Solaris 8.</li>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]359<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
360 support is available for native builds with Visual C++).</li>
361<li>PowerPC-based Mac OS X systems, running 10.2 and above.</li>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]362<li>Alpha-based machines running Debian GNU/Linux.</li>
363<li>Itanium-based machines running Linux and HP-UX.</li>
Chris Lattner2c7b0872004-06-01 18:22:41 +0000[diff] [blame]364</ul>
365
Brian Gaekee3e557e2004-05-09 05:28:35 +0000[diff] [blame]366<p>The core LLVM infrastructure uses
367<a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
368to the machine and operating system on which it is built. However, minor
369porting may be required to get LLVM to work on new platforms. We welcome your
370portability patches and reports of successful builds or error messages.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]371
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]372</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]373
374<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]375<div class="doc_section">
376 <a name="knownproblems">Known Problems</a>
377</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]378<!-- *********************************************************************** -->
379
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]380<div class="doc_text">
381
382<p>This section contains all known problems with the LLVM system, listed by
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]383component. As new problems are discovered, they will be added to these
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]384sections. If you run into a problem, please check the <a
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]385href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
Chris Lattnerb84f3322003-12-12 21:22:16 +0000[diff] [blame]386there isn't already one.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]387
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]388</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]389
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]390<!-- ======================================================================= -->
391<div class="doc_subsection">
392 <a name="experimental">Experimental features included with this release</a>
393</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]394
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]395<div class="doc_text">
396
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]397<p>The following components of this LLVM release are either untested, known to
398be broken or unreliable, or are in early development. These components should
399not be relied on, and bugs should not be filed against them, but they may be
400useful to some people. In particular, if you would like to work on one of these
401components, please contact us on the llvmdev list.</p>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]402
403<ul>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]404<li>The following passes are incomplete or buggy, and may be removed in future
Chris Lattner38389b12005-01-28 06:13:52 +0000[diff] [blame]405 releases: <tt>-cee, -branch-combine, -instloops, -paths, -pre</tt></li>
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]406<li>The <tt>llvm-db</tt> tool is in a very early stage of development, but can
407 be used to step through programs and inspect the stack.</li>
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]408<li>The "iterative scan" register allocator (enabled with
409 <tt>-regalloc=iterativescan</tt>) is not stable.</li>
John Criswelld5234922005-05-13 20:28:15 +0000[diff] [blame]410<li>The SparcV8, Alpha, and IA64 code generators are experimental.</li>
Chris Lattnerb911de42004-03-14 02:03:02 +0000[diff] [blame]411</ul>
412
413</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]414
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]415<!-- ======================================================================= -->
416<div class="doc_subsection">
417 <a name="core">Known problems with the LLVM Core</a>
418</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]419
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]420<div class="doc_text">
421
422<ul>
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]423 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
424 work.</li>
Reid Spencer493d9c22004-11-25 22:38:30 +0000[diff] [blame]425 <li>The JIT does not use mutexes to protect its internal data structures. As
426 such, execution of a threaded program could cause these data structures to be
427 corrupted.
428 </li>
Reid Spencer493d9c22004-11-25 22:38:30 +0000[diff] [blame]429 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
430 mark values live across a setjmp as volatile</a>. This missing feature
431 only affects targets whose setjmp/longjmp libraries do not save and restore
432 the entire register file.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]433</ul>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]434</div>
435
436<!-- ======================================================================= -->
437<div class="doc_subsection">
438 <a name="c-fe">Known problems with the C front-end</a>
439</div>
Chris Lattner178f3db2003-10-02 05:07:23 +0000[diff] [blame]440
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]441<!-- _______________________________________________________________________ -->
Chris Lattner5a8a7282003-12-14 05:03:43 +0000[diff] [blame]442<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]443
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]444<div class="doc_text">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]445<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]446<li>C99 Variable sized arrays do not release stack memory when they go out of
447 scope. Thus, the following program may run out of stack space:
448<pre>
449 for (i = 0; i != 1000000; ++i) {
450 int X[n];
451 foo(X);
452 }
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]453</pre></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]454
Misha Brukmanfa50a222004-05-12 21:46:05 +0000[diff] [blame]455<li>Initialization of global union variables can only be done <a
Misha Brukman68ef9a92004-12-04 00:45:09 +0000[diff] [blame]456href="http://llvm.cs.uiuc.edu/PR162">with the largest union member</a>.</li>
Chris Lattner1ab58dd2004-03-16 21:39:04 +0000[diff] [blame]457
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]458</ul>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]459</div>
460
461<!-- _______________________________________________________________________ -->
462<div class="doc_subsubsection">
463 Notes
464</div>
465
466<div class="doc_text">
467
468<ul>
469
470<li>Inline assembly is not yet supported.</li>
Chris Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]471
472<li>"long double" is transformed by the front-end into "double". There is no
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]473support for floating point data types of any size other than 32 and 64
474bits.</li>
475
476<li>The following Unix system functionality has not been tested and may not
477work:
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]478 <ol>
479 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
480 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
481 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
482 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
483 - These functions have not been tested.
484 </ol></li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]485
486<li>Although many GCC extensions are supported, some are not. In particular,
487 the following extensions are known to <b>not be</b> supported:
488 <ol>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]490 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>: As in Algol and Pascal, lexical scoping of functions.</li>
491 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
492 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]494 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Asm-Labels.html#Asm%20Labels">Asm Labels</a>: Specifying the assembler name to use for a C symbol.</li>
495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Explicit-Reg-Vars.html#Explicit%20Reg%20Vars">Explicit Reg Vars</a>: Defining variables residing in specified registers.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]496 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
497 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
Tanya Lattner63371342004-12-08 18:25:34 +0000[diff] [blame]498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]500 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]501
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]502 <p>The following GCC extensions are <b>partially</b> supported. An ignored
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]503 attribute means that the LLVM compiler ignores the presence of the attribute,
504 but the code should still work. An unsupported attribute is one which is
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]505 ignored by the LLVM compiler and will cause a different interpretation of
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]506 the program.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]507
508 <ol>
509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
510 Arrays whose length is computed at run time.<br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]511 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]512
513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]514
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]515 Declaring that functions have no side effects or that they can never
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]516 return.<br>
517
518 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]519 <tt>noreturn</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
520 <tt>unused</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]521 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
522
John Criswell64307722004-12-08 20:35:47 +0000[diff] [blame]523 <b>Ignored:</b> <tt>noinline</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]524 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
525 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
526
527 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
528 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
529 <tt>fastcall</tt>, all other target specific attributes</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]530
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
532 Specifying attributes of variables.<br>
533 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
534 <tt>deprecated</tt>, <tt>transparent_union</tt>,
535 <tt>unused</tt>, <tt>weak</tt><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]536
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]537 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
538 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
539 <tt>vector_size</tt>, <tt>dllimport</tt>,
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]540 <tt>dllexport</tt>, all target specific attributes.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]541
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]542 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]543 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]544 <tt>deprecated</tt>, <tt>may_alias</tt><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]545
546 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
547 all target specific attributes.</li>
548
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
550 Other built-in functions.<br>
551 We support all builtins which have a C language equivalent (e.g.,
552 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
553 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
Chris Lattnerb7c4bac2004-06-18 06:26:29 +0000[diff] [blame]554 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
555 (currently ignored). We also support builtins for ISO C99 floating
Chris Lattnerb34b2732005-05-07 02:21:21 +0000[diff] [blame]556 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
557 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
558 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]559 </ol>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]560
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]561 <p>The following extensions <b>are</b> known to be supported:</p>
562
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]563 <ol>
Chris Lattnerd3dc8502004-03-16 08:54:07 +0000[diff] [blame]564 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html#Labels%20as%20Values">Labels as Values</a>: Getting pointers to labels and computed gotos.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]565 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
566 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
Tanya Lattnerce33a1b2004-06-22 03:48:17 +0000[diff] [blame]567 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]568 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
569 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
570 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
572 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
573 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
574 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
575 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
576 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]577 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pointer-Arith.html#Pointer%20Arith">Pointer Arith</a>: Arithmetic on <code>void</code>-pointers and function pointers.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]578 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
580or arrays as values.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]581 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
Misha Brukman8395d732003-12-12 04:37:31 +0000[diff] [blame]582 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Cast-to-Union.html#Cast%20to%20Union">Cast to Union</a>: Casting to union type from any member of the union.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]583 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
584 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
585 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
Tanya Lattner7591b822004-12-08 18:29:38 +0000[diff] [blame]586 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]587 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
588 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character &lt;ESC&gt;.</li>
589 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
590 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
591 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate%20Keywords">Alternate Keywords</a>:<code>__const__</code>, <code>__asm__</code>, etc., for header files.</li>
592 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>: <code>enum foo;</code>, with details to follow.</li>
593 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Names.html#Function%20Names">Function Names</a>: Printable strings which are the name of the current function.</li>
Chris Lattner3646dad2004-02-14 04:08:29 +0000[diff] [blame]594 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html#Return%20Address">Return Address</a>: Getting the return or frame address of a function.</li>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]595 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
596 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]597 </ol></li>
598
599</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]600
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]601<p>If you run into GCC extensions which have not been included in any of these
602lists, please let us know (also including whether or not they work).</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]603
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]604</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]605
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]606<!-- ======================================================================= -->
607<div class="doc_subsection">
608 <a name="c++-fe">Known problems with the C++ front-end</a>
609</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]610
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]611<div class="doc_text">
612
Reid Spencer55684c32004-12-07 08:39:08 +0000[diff] [blame]613<p>For this release, the C++ front-end is considered to be fully
Chris Lattnerb5bb5972004-12-07 08:04:13 +0000[diff] [blame]614tested and works for a number of non-trivial programs, including LLVM
615itself.</p>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]616
617</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]618
619<!-- _______________________________________________________________________ -->
Chris Lattner141ebb62004-02-14 04:12:41 +0000[diff] [blame]620<div class="doc_subsubsection">Bugs</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]621
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]622<div class="doc_text">
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]623
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]624<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]625<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]626 front-end</a>.</li>
Chris Lattner041e6c92004-07-17 02:04:41 +0000[diff] [blame]627
Chris Lattner5cd40922004-08-02 20:28:44 +0000[diff] [blame]628</ul>
629
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]630</div>
631
632<!-- _______________________________________________________________________ -->
633<div class="doc_subsubsection">
634 Notes
635</div>
636
637<div class="doc_text">
638
639<ul>
Chris Lattnerd2a74272003-10-27 18:30:37 +0000[diff] [blame]640
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]641<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
642parser is significantly more standards compliant (and picky) than prior GCC
643versions. For more information, see the C++ section of the <a
Chris Lattnere76e9ab2003-12-12 04:25:33 +0000[diff] [blame]644href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]645
646<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]647 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]648 function and in the <tt>setjmp</tt> receiver function may not be run.
John Criswell86a3a482003-12-18 16:43:17 +0000[diff] [blame]649 Objects in intervening stack frames will be destroyed, however (which is
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]650 better than most compilers).</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]651
Chris Lattner62495762003-10-02 16:38:05 +0000[diff] [blame]652<li>The LLVM C++ front-end follows the <a
653 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
654 This document, which is not Itanium specific, specifies a standard for name
655 mangling, class layout, v-table layout, RTTI formats, and other C++
656 representation issues. Because we use this API, code generated by the LLVM
657 compilers should be binary compatible with machine code generated by other
658 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
659 <i>However</i>, the exception handling mechanism used by LLVM is very
660 different from the model used in the Itanium ABI, so <b>exceptions will not
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]661 interact correctly</b>. </li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]662
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]663</ul>
Chris Lattner46ecf612003-10-07 22:14:37 +0000[diff] [blame]664
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]665</div>
666
667<!-- ======================================================================= -->
668<div class="doc_subsection">
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]669 <a name="c-be">Known problems with the C back-end</a>
670</div>
671
672<div class="doc_text">
673
674<ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]675
676<li>The C back-end produces code that violates the ANSI C Type-Based Alias
677Analysis rules. As such, special options may be necessary to compile the code
678(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]679problem probably cannot be fixed.</li>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]680
Chris Lattnerc679fbb2003-11-04 20:06:53 +0000[diff] [blame]681<li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]682supported</a>. This should not affect LLVM produced by the C or C++
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]683frontends.</li>
Chris Lattnerb28c3282003-10-24 04:03:19 +0000[diff] [blame]684
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]685</ul>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]686
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]687</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]688
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]689<!-- ======================================================================= -->
690<div class="doc_subsection">
Chris Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame^]691 <a name="x86-be">Known problems with the X86 back-end</a>
692</div>
693
694<div class="doc_text">
695
696<ul>
697 <li>None yet</li>
698</ul>
699
700</div>
701
702<!-- ======================================================================= -->
703<div class="doc_subsection">
704 <a name="ppc-be">Known problems with the PowerPC back-end</a>
705</div>
706
707<div class="doc_text">
708
709<ul>
710<li>None yet</li>
711</ul>
712
713</div>
714
715<!-- ======================================================================= -->
716<div class="doc_subsection">
717 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
718</div>
719
720<div class="doc_text">
721
722<ul>
723<li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
724several programs in the LLVM test suite</a></li>
725</ul>
726
727</div>
728
729<!-- ======================================================================= -->
730<div class="doc_subsection">
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]731 <a name="alpha-be">Known problems with the Alpha back-end</a>
732</div>
733
734<div class="doc_text">
735
736<ul>
737
Chris Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame^]738<li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
739appropriate nops inserted to ensure restartability.</li>
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]740
Chris Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame^]741<li>Defining vararg functions is not supported (but calling them is ok).</li>
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]742
Andrew Lenharth8ecaa452005-05-14 17:43:00 +0000[diff] [blame]743<li>Due to the vararg problems, C++ exceptions do not work. Small changes are required to the CFE (which break correctness in the exception handler) to compile the exception handling library (and thus the C++ standard library).</li>
744
Andrew Lenharth2e18c622005-05-03 16:59:09 +0000[diff] [blame]745</ul>
746
747</div>
748
Duraid Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]749<!-- ======================================================================= -->
750<div class="doc_subsection">
751 <a name="ia64-be">Known problems with the IA64 back-end</a>
752</div>
753
754<div class="doc_text">
755
756<ul>
757
758<li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
759made where the argument is not 16-byte aligned, as required on IA64. (Strictly
760speaking this is not a bug in the IA64 back-end; it will also be encountered
761when building C++ programs using the C back-end.)</li>
762
Chris Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame^]763<li>The C++ front-end does not use <a href="http://llvm.cs.uiuc.edu/PR406">IA64
764ABI compliant layout of v-tables</a>. In particular, it just stores function
765pointers instead of function descriptors in the vtable. This bug prevents
766mixing C++ code compiled with LLVM with C++ objects compiled by other C++
767compilers.</li>
Duraid Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]768
Chris Lattner683a8472005-05-16 17:06:29 +0000[diff] [blame^]769<li>There are a few ABI violations which will lead to problems when mixing LLVM
770output with code built with other compilers, particularly for floating-point
771programs.</li>
772
773<li>Defining vararg functions is not supported (but calling them is ok).</li>
Duraid Madina9a449002005-05-14 05:48:13 +0000[diff] [blame]774
775</ul>
776
777</div>
778
Chris Lattnerb62a5f02005-05-15 16:01:20 +0000[diff] [blame]779<!-- ======================================================================= -->
780<div class="doc_subsection">
781 <a name="sparcv8">Known problems with the SPARC-V8 back-end</a>
782</div>
783
784<div class="doc_text">
785
786<ul>
787<li>Many features are still missing (e.g. support for 64-bit integer
788arithmetic).</li>
789
790<li>This backend needs to be updated to use the SelectionDAG instruction
791selection framework.</li>
792</ul>
793
794</div>
795
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]796<!-- *********************************************************************** -->
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]797<div class="doc_section">
798 <a name="additionalinfo">Additional Information</a>
799</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]800<!-- *********************************************************************** -->
801
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]802<div class="doc_text">
803
804<p>A wide variety of additional information is available on the LLVM web page,
Misha Brukman96158092005-03-30 19:14:24 +0000[diff] [blame]805including <a href="http://llvm.cs.uiuc.edu/docs/#maillist">mailing lists</a> and
806<a href="http://llvm.cs.uiuc.edu/pubs/">publications describing algorithms and
807components implemented in LLVM</a>. The web page also contains versions of the
808API documentation which is up-to-date with the CVS version of the source code.
809You can access versions of these documents specific to this release by going
810into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]811
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]812<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]813us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
814lists</a>.</p>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]815
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]816</div>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]817
818<!-- *********************************************************************** -->
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]819
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]820<hr>
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]821<address>
Misha Brukman8834af92003-12-21 22:53:21 +0000[diff] [blame]822 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]823 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
824 <a href="http://validator.w3.org/check/referer"><img
825 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
826
Misha Brukman7cb4e382003-11-22 01:00:11 +0000[diff] [blame]827 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]828 Last modified: $Date$
Misha Brukman68aab3b2003-11-22 01:23:39 +0000[diff] [blame]829</address>
Chris Lattner3d482502003-10-02 04:57:28 +0000[diff] [blame]830
Misha Brukman80731b92003-11-22 00:38:41 +0000[diff] [blame]831</body>
832</html>