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2<html><head><title>LLVM 1.0 Release Notes</title></head>
3<body bgcolor=white>
4
5<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
6<tr><td>&nbsp; <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM 1.0 Release Notes</b></font></td>
7</tr></table>
8
9<ol>
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]10 <li><a href="#intro">Introduction</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]11 <li><a href="#whatsnew">What's New?</a>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]12 <li><a href="#portability">Portability and Supported Platforms</a>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]13 <li><a href="#install-instructions">Installation Instructions</a>
14 <li><a href="#knownproblems">Known Problems</a>
15 <ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]16<!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]17 <li><a href="#core">Known problems with the LLVM Core</a>
18 <li><a href="#c-fe">Known problems with the C Front-end</a>
19 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
20 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
21 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
22 <li><a href="#c-be">Known problems with the C back-end</a>
23 </ul>
24 <li><a href="#additionalinfo">Additional Information</a>
25 </ul>
26
27 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
28</ol>
29
30
31<!-- *********************************************************************** -->
32<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
33<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
34<a name="intro">Introduction
35</b></font></td></tr></table><ul>
36<!-- *********************************************************************** -->
37
38This document contains the release notes for the LLVM compiler infrastructure,
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]39release 1.0. Here we describe how to install LLVM, as well as any known
40problems. The most up-to-date version of this document can be found on the <a
41href="http://llvm.cs.uiuc.edu/releases/1.0/">LLVM 1.0 web site</a>. If you are
42not reading this on the LLVM web pages, you should probably go there, because
43this document may be updated after the release.<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]44
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]45For more information about LLVM, including information about potentially more
46current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
47web site</a>. If you have questions or comments, the <a
48href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
49list</a> is a good place to send them.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]50
51
52<!-- *********************************************************************** -->
53</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
54<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
55<a name="whatsnew">What's New?
56</b></font></td></tr></table><ul>
57<!-- *********************************************************************** -->
58
59This is the first public release of the LLVM compiler infrastructure. As such,
60it is all new! In particular, we are providing a stable C compiler, beta C++
61compiler, a C back-end, stable X86 and Sparc V9 static and JIT code generators,
62as well as a large suite of scalar and interprocedural optimizations.<p>
63
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]64The default optimizer sequence used by the C/C++ front-ends is:<p>
65
66<ol>
67<li>Interprocedural dead code elimination (-globaldce)
68<li>Exception handling pruning (-prune-eh)
69<li>Function inlining (-inline)
70<li>Instruction combining (-instcombine)
71<li>Cast elimination (-raise)
72<li>Tail duplication (-tailduplicate)
73<li>CFG simplification (-simplifycfg)
74<li>Scalar replacement of aggregates (-scalarrepl)
75<li>Tail call elimination (-tailcallelim)
76<li>Instruction combining (-instcombine)
77<li>Reassociation (-reassociate)
78<li>Instruction combining (-instcombine)
79<li>CFG simplification (-simplifycfg)
80<li>Loop canonnicalization (-preheaders)
81<li>Loop invariant code motion, with scalar promotion (-licm)
82<li>Global common subexpression elimination, with load elimination (-gcse)
83<li>Sparse conditional constant propagation (-sccp)
84<li>Instruction combining (-instcombine)
85<li>Induction variable canonicalization (-indvars)
86<li>Aggressive dead code elimination (-adce)
87<li>CFG simplication (-simplifycfg)
88<li>Dead type elimination (-deadtypeelim)
89<li>Global constant merging (-constmerge)
90</ol><p>
91
92At link-time, the following optimizations are run:<p>
93
94<ol>
95<li>Global constant merging (-constmerge)
96<li>[optional] Internalization [which marks most functions and global variables static] (-internalize)
97<li>Interprocedural dead argument elimination (-deadargelim)
98<li>Instruction combining (-instcombine)
99<li>CFG simplification (-simplifycfg)
100<li>Interprocedural dead code elimination (-globaldce)
101</ol><p>
102
103
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]104TODO: Works on: SPEC CPU 2000<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]105TODO: Works on: Olden/Ptrdist benchmarks<p>
106
107The What's New section should give a bulletted list of what is
108included, perhaps a couple of lists (Stable, Beta).<p>
109
110It would be useful to give a pointer to a list of the available passes (at least
111for the standard compiler techniques).<p>
112
113
114<!-- *********************************************************************** -->
115</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
116<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
117<a name="portability">Portability and Supported Platforms
118</b></font></td></tr></table><ul>
119<!-- *********************************************************************** -->
120
121LLVM has only been extensively tested on ia32-linux and sparc-solaris machines.
122The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
123work on more platforms than that. However, it is extremely likely that we
124missed something. We welcome portability patches and error messages.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]125
126
127<!-- *********************************************************************** -->
128</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
129<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
130<a name="install-instructions">Installation Instructions
131</b></font></td></tr></table><ul>
132<!-- *********************************************************************** -->
133
134FIXME
135
136
137<!-- *********************************************************************** -->
138</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
139<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
140<a name="knownproblems">Known Problems
141</b></font></td></tr></table><ul>
142<!-- *********************************************************************** -->
143
144This section contains all known problems with the LLVM system, listed by
145component. As new problems are discovered, they will be added to these
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]146sections.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]147
148
149<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]150<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]151</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]152-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]153
154
155<!-- _______________________________________________________________________ -->
156</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
157
158<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
159
160<li>The JIT does not use mutexes to protect its internal data structures. As
161 such, execution of a threaded program could cause these data structures to
162 be corrupted.<p>
163
164<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
165
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]166<li>Linking in static archive files (.a files) is very slow.
167
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]168<!-- _______________________________________________________________________ -->
169</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
170
171<li>Inline assembly is not yet supported.<p>
172
173<li>"long double" is transformed by the front-end into "double". There is no
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]174 support for floating point data types of any size other than 32 and 64 bits.
175 <p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]176<li>C99 Variable sized arrays do not release stack memory when they go out of
177 scope. Thus, the following program may run out of stack space:
178<pre>
179 for (i = 0; i != 1000000; ++i) {
180 int X[n];
181 foo(X);
182 }
183</pre><p>
184
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]185<li>The following Unix system functionality has not been tested and may not work:
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]186<ol>
187 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
188 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
189 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
190 - These functions have not been tested.
191</ol><p>
192
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]193<li>Bugs:<br>
194 <a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=6">Oversized integer bitfields cause crash</a>.<br>
195 <a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=9">LLVM needs explicit support for weak variables</a>.<br>
196<p>
197
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]198<li>Although many GCC extensions are supported, some are not. In particular,
199 the following extensions are known to <b>not be</b> supported:
200 <ol>
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
202 <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.
203 <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.
204 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
205 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
207 <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.
208 <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.
209 <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.
210 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
211 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
212 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
213 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
214 </ol><p>
215
216 The following GCC extensions are <b>partially</b> supported. An ignored
217 attribute means that the LLVM compiler ignores the presence of the attribute,
218 but the code should still work. An unsupported attribute is one which is
219 ignored by the LLVM compiler, which will cause a different interpretation of
220 the program.<p>
221
222 <ol>
223 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
224 Arrays whose length is computed at run time.<br>
225 Supported, but allocated stack space is not freed until the function returns (noted above).
226
227 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
228 Declaring that functions have no side effects, or that they can never return.<br>
229 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>, <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>, <tt>deprecated</tt>,
230 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
231 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>, <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>, <tt>malloc</tt>
232 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
233 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
234 <tt>fastcall</tt>, all other target specific attributes
235
236 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
237 Specifying attributes of variables.<br>
238 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
239 <tt>deprecated</tt>, <tt>transparent_union</tt>,
240 <tt>unused</tt>, <tt>weak</tt><br>
241 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
242 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
243 <tt>vector_size</tt>, <tt>dllimport</tt>,
244 <tt>dllexport</tt>, all target specific attributes.<br>
245
246 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
247 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
248 <tt>deprecated</tt>, <tt>may_alias</tt>
249 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
250 all target specific attributes.<br>
251 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
252 Other built-in functions.<br>
253 We support all builtins which have a C language equivalent (e.g.,
254 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
255 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
256 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
257 </ol><p>
258
259
260 The following extensions <b>are</b> known to be supported:
261 <ol>
262 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
263 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]264 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]265 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
266 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
267 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
268 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
269 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
270 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
271 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
272 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
273 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
274 <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.
275 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
276 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions or arrays as values.
277 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
278
279 <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.
280 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
281 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
282
283 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
284 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
285 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
286 <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;.
287 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
288 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
289 <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.
290 <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.
291 <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.
292 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
293 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
294 </ol><p>
295
296 If you run into GCC extensions which have not been included in any of these
297 lists, please let us know (also including whether or not they work).
298
299
300<!-- _______________________________________________________________________ -->
301</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
302
303For this release, the C++ front-end is considered to be of <b>beta</b> quality.
304It works for a large number of simple programs, but has not been extensively
305tested. We welcome bug reports though!<p>
306
307<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
308 front-end</a><p>
309
310<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
311parser is significantly more standards compliant (and picky) than prior GCC
312versions. For more information, see the C++ section of the <a
313href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
314
315<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]316 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]317 function and in the <tt>setjmp</tt> receiver function may not be run.
318 Objects in intervening stack frames will be destroyed however (which is
319 better than most compilers).<p>
320
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]321<li>The LLVM C++ front-end follows the <a
322 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
323 This document, which is not Itanium specific, specifies a standard for name
324 mangling, class layout, v-table layout, RTTI formats, and other C++
325 representation issues. Because we use this API, code generated by the LLVM
326 compilers should be binary compatible with machine code generated by other
327 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
328 <i>However</i>, the exception handling mechanism used by LLVM is very
329 different from the model used in the Itanium ABI, so <b>exceptions will not
330 interact correctly</b> .
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]331
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]332<li><a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=11">Code for executing
333destructors when unwinding is not shared</a>.
334
335
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]336<!-- _______________________________________________________________________ -->
337</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
338
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]339<li>The X86 code generator <a
340href="http://zion.cs.uiuc.edu/bugs/show_bug.cgi?id=16">does not currently
341support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
342or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]343
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]344<li><a href="http://zion.cs.uiuc.edu/bugs/show_bug.cgi?id=4">Some executables
345produced by LLC seem to intermittently crash (extremely infrequently)</a>. The
346cause of the problem has not been diagnosed, and does not affect the JIT.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]347
348
349<!-- _______________________________________________________________________ -->
350</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
351
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]352<li>The Sparc code generator <a
353href="http://zion.cs.uiuc.edu/bugs/show_bug.cgi?id=15">does not currently
354support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
355or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]356
357
358<!-- _______________________________________________________________________ -->
359</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
360
361<li>The C back-end produces code that violates the ANSI C Type-Based Alias
362Analysis rules. As such, special options may be necessary to compile the code
363(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
364problem probably cannot be fixed.<p>
365
366<li>Initializers for global variables that include floating point numbers may
367not be initialized with exactly the right floating point number, if the number
368is not accurately representable in decimal. This prevents the Olden "power"
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]369benchmark from producing exactly the right results with the C back-end.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]370
371<li>The code produces by the C back-end has only been tested with the Sun CC and
372GCC compilers. It is possible that it will have to be adjusted to support other
373C compilers.<p>
374
375
376
377<!-- *********************************************************************** -->
378</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
379<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
380<a name="additionalinfo">Additional Information
381</b></font></td></tr></table><ul>
382<!-- *********************************************************************** -->
383
384A wide variety of additional information is available on the LLVM web page,
385including mailing lists publications describing algorithms and components
386implemented in LLVM. The web page also contains versions of the API
387documentation which is up-to-date with the CVS version of the source code. You
388can access versions of these documents specific to this release by going into
389the "<tt>llvm/www/doc/</tt>" directory in the LLVM tree.<p>
390
391If you have any questions or comments about LLVM, please feel free to contact us
392via the mailing lists.<p>
393
394
395<!-- *********************************************************************** -->
396</ul>
397<!-- *********************************************************************** -->
398
399<hr><font size-1>
400
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]401Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]402<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
403<!-- hhmts start -->
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame^]404Last modified: Tue Oct 7 17:10:14 CDT 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]405<!-- hhmts end -->
406</body></html>