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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)
Chris Lattnerd59128a2003-10-12 21:51:55 +0000[diff] [blame]80<li>Loop canonicalization (-loopsimplify)
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]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
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]103At this time, LLVM is known to work properly with SPEC CPU 2000, the Olden
104benchmarks, and the Ptrdist benchmarks among many other programs. Note however
105that the Sparc and X86 backends do not currently support exception throwing or
106long jumping. For these programs you must use the C backend.<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]107
108
109<!-- *********************************************************************** -->
110</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
111<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
112<a name="portability">Portability and Supported Platforms
113</b></font></td></tr></table><ul>
114<!-- *********************************************************************** -->
115
116LLVM has only been extensively tested on ia32-linux and sparc-solaris machines.
117The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
118work on more platforms than that. However, it is extremely likely that we
119missed something. We welcome portability patches and error messages.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]120
121
122<!-- *********************************************************************** -->
123</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
124<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
125<a name="install-instructions">Installation Instructions
126</b></font></td></tr></table><ul>
127<!-- *********************************************************************** -->
128
129FIXME
130
131
132<!-- *********************************************************************** -->
133</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
134<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
135<a name="knownproblems">Known Problems
136</b></font></td></tr></table><ul>
137<!-- *********************************************************************** -->
138
139This section contains all known problems with the LLVM system, listed by
140component. As new problems are discovered, they will be added to these
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]141sections.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]142
143
144<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]145<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]146</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]147-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]148
149
150<!-- _______________________________________________________________________ -->
151</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
152
153<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
154
155<li>The JIT does not use mutexes to protect its internal data structures. As
156 such, execution of a threaded program could cause these data structures to
157 be corrupted.<p>
158
159<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
160
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]161<li>Linking in static archive files (.a files) is very slow (there is no symbol
162table in the archive).
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]163
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]164<!-- _______________________________________________________________________ -->
165</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
166
167<li>Inline assembly is not yet supported.<p>
168
169<li>"long double" is transformed by the front-end into "double". There is no
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]170 support for floating point data types of any size other than 32 and 64 bits.
171 <p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]172<li>C99 Variable sized arrays do not release stack memory when they go out of
173 scope. Thus, the following program may run out of stack space:
174<pre>
175 for (i = 0; i != 1000000; ++i) {
176 int X[n];
177 foo(X);
178 }
179</pre><p>
180
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]181<li>The following Unix system functionality has not been tested and may not work:
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]182<ol>
183 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
184 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
185 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
186 - These functions have not been tested.
187</ol><p>
188
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]189<li>Bugs:<br>
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]190 <a href="http://llvm.cs.uiuc.edu/PR6">Oversized integer bitfields cause crash</a>.<br>
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]191<p>
192
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]193<li>Although many GCC extensions are supported, some are not. In particular,
194 the following extensions are known to <b>not be</b> supported:
195 <ol>
196 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
197 <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.
198 <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.
199 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
200 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
202 <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.
203 <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.
204 <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.
205 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
207 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
208 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
209 </ol><p>
210
211 The following GCC extensions are <b>partially</b> supported. An ignored
212 attribute means that the LLVM compiler ignores the presence of the attribute,
213 but the code should still work. An unsupported attribute is one which is
214 ignored by the LLVM compiler, which will cause a different interpretation of
215 the program.<p>
216
217 <ol>
218 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
219 Arrays whose length is computed at run time.<br>
220 Supported, but allocated stack space is not freed until the function returns (noted above).
221
222 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
223 Declaring that functions have no side effects, or that they can never return.<br>
224 <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>,
225 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
226 <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>
227 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
228 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
229 <tt>fastcall</tt>, all other target specific attributes
230
231 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
232 Specifying attributes of variables.<br>
233 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
234 <tt>deprecated</tt>, <tt>transparent_union</tt>,
235 <tt>unused</tt>, <tt>weak</tt><br>
236 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
237 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
238 <tt>vector_size</tt>, <tt>dllimport</tt>,
239 <tt>dllexport</tt>, all target specific attributes.<br>
240
241 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
242 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
243 <tt>deprecated</tt>, <tt>may_alias</tt>
244 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
245 all target specific attributes.<br>
246 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
247 Other built-in functions.<br>
248 We support all builtins which have a C language equivalent (e.g.,
249 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
250 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
251 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
252 </ol><p>
253
254
255 The following extensions <b>are</b> known to be supported:
256 <ol>
257 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
258 <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]259 <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]260 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
261 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
262 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
263 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
264 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
265 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
266 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
267 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
268 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
269 <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.
270 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
271 <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.
272 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
273
274 <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.
275 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
276 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
277
278 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
279 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
280 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
281 <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;.
282 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
283 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
284 <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.
285 <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.
286 <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.
287 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
288 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
289 </ol><p>
290
291 If you run into GCC extensions which have not been included in any of these
292 lists, please let us know (also including whether or not they work).
293
294
295<!-- _______________________________________________________________________ -->
296</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
297
298For this release, the C++ front-end is considered to be of <b>beta</b> quality.
299It works for a large number of simple programs, but has not been extensively
300tested. We welcome bug reports though!<p>
301
302<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
303 front-end</a><p>
304
305<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
306parser is significantly more standards compliant (and picky) than prior GCC
307versions. For more information, see the C++ section of the <a
308href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
309
310<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]311 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]312 function and in the <tt>setjmp</tt> receiver function may not be run.
313 Objects in intervening stack frames will be destroyed however (which is
314 better than most compilers).<p>
315
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]316<li>The LLVM C++ front-end follows the <a
317 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
318 This document, which is not Itanium specific, specifies a standard for name
319 mangling, class layout, v-table layout, RTTI formats, and other C++
320 representation issues. Because we use this API, code generated by the LLVM
321 compilers should be binary compatible with machine code generated by other
322 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
323 <i>However</i>, the exception handling mechanism used by LLVM is very
324 different from the model used in the Itanium ABI, so <b>exceptions will not
325 interact correctly</b> .
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]326
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]327<li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]328destructors when unwinding is not shared</a>.
329
330
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]331<!-- _______________________________________________________________________ -->
332</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
333
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]334<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]335href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]336support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
337or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]338
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]339
340<!-- _______________________________________________________________________ -->
341</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
342
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]343<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]344href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]345support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
346or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]347
348
349<!-- _______________________________________________________________________ -->
350</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
351
352<li>The C back-end produces code that violates the ANSI C Type-Based Alias
353Analysis rules. As such, special options may be necessary to compile the code
354(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
355problem probably cannot be fixed.<p>
356
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]357<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
358cannot include special floating point numbers like Not-A-Number or Infinity.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]359
360<li>The code produces by the C back-end has only been tested with the Sun CC and
361GCC compilers. It is possible that it will have to be adjusted to support other
362C compilers.<p>
363
364
365
366<!-- *********************************************************************** -->
367</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
368<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
369<a name="additionalinfo">Additional Information
370</b></font></td></tr></table><ul>
371<!-- *********************************************************************** -->
372
373A wide variety of additional information is available on the LLVM web page,
374including mailing lists publications describing algorithms and components
375implemented in LLVM. The web page also contains versions of the API
376documentation which is up-to-date with the CVS version of the source code. You
377can access versions of these documents specific to this release by going into
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]378the "<tt>llvm/doc/</tt>" directory in the LLVM tree.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]379
380If you have any questions or comments about LLVM, please feel free to contact us
381via the mailing lists.<p>
382
383
384<!-- *********************************************************************** -->
385</ul>
386<!-- *********************************************************************** -->
387
388<hr><font size-1>
389
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]390Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]391<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
392<!-- hhmts start -->
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]393Last modified: Mon Oct 20 14:04:51 CDT 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]394<!-- hhmts end -->
395</body></html>