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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
Brian Gaeke15a2a252003-10-22 18:19:08 +0000[diff] [blame^]116LLVM has only been extensively tested on Intel and AMD machines running Red
117Hat Linux, and Sun UltraSPARC workstations running Solaris 8.
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]118The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
119work on more platforms than that. However, it is extremely likely that we
120missed something. We welcome portability patches and error messages.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]121
122
123<!-- *********************************************************************** -->
124</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
125<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
126<a name="install-instructions">Installation Instructions
127</b></font></td></tr></table><ul>
128<!-- *********************************************************************** -->
129
130FIXME
131
132
133<!-- *********************************************************************** -->
134</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
135<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
136<a name="knownproblems">Known Problems
137</b></font></td></tr></table><ul>
138<!-- *********************************************************************** -->
139
140This section contains all known problems with the LLVM system, listed by
141component. As new problems are discovered, they will be added to these
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]142sections.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]143
144
145<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]146<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]147</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]148-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]149
150
151<!-- _______________________________________________________________________ -->
152</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
153
154<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
155
156<li>The JIT does not use mutexes to protect its internal data structures. As
157 such, execution of a threaded program could cause these data structures to
158 be corrupted.<p>
159
160<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
161
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]162<li>Linking in static archive files (.a files) is very slow (there is no symbol
163table in the archive).
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]164
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]165<!-- _______________________________________________________________________ -->
166</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
167
168<li>Inline assembly is not yet supported.<p>
169
170<li>"long double" is transformed by the front-end into "double". There is no
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]171 support for floating point data types of any size other than 32 and 64 bits.
172 <p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]173<li>C99 Variable sized arrays do not release stack memory when they go out of
174 scope. Thus, the following program may run out of stack space:
175<pre>
176 for (i = 0; i != 1000000; ++i) {
177 int X[n];
178 foo(X);
179 }
180</pre><p>
181
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]182<li>The following Unix system functionality has not been tested and may not work:
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]183<ol>
184 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
185 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
186 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
187 - These functions have not been tested.
188</ol><p>
189
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]190<li>Bugs:<br>
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]191 <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]192<p>
193
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]194<li>Although many GCC extensions are supported, some are not. In particular,
195 the following extensions are known to <b>not be</b> supported:
196 <ol>
197 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
198 <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.
199 <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.
200 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
202 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
203 <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.
204 <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.
205 <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.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
207 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
208 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
209 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
210 </ol><p>
211
212 The following GCC extensions are <b>partially</b> supported. An ignored
213 attribute means that the LLVM compiler ignores the presence of the attribute,
214 but the code should still work. An unsupported attribute is one which is
215 ignored by the LLVM compiler, which will cause a different interpretation of
216 the program.<p>
217
218 <ol>
219 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
220 Arrays whose length is computed at run time.<br>
221 Supported, but allocated stack space is not freed until the function returns (noted above).
222
223 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
224 Declaring that functions have no side effects, or that they can never return.<br>
225 <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>,
226 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
227 <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>
228 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
229 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
230 <tt>fastcall</tt>, all other target specific attributes
231
232 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
233 Specifying attributes of variables.<br>
234 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
235 <tt>deprecated</tt>, <tt>transparent_union</tt>,
236 <tt>unused</tt>, <tt>weak</tt><br>
237 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
238 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
239 <tt>vector_size</tt>, <tt>dllimport</tt>,
240 <tt>dllexport</tt>, all target specific attributes.<br>
241
242 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
243 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
244 <tt>deprecated</tt>, <tt>may_alias</tt>
245 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
246 all target specific attributes.<br>
247 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
248 Other built-in functions.<br>
249 We support all builtins which have a C language equivalent (e.g.,
250 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
251 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
252 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
253 </ol><p>
254
255
256 The following extensions <b>are</b> known to be supported:
257 <ol>
258 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
259 <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]260 <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]261 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
262 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
263 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
264 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
265 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
266 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
267 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
268 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
269 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
270 <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.
271 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
272 <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.
273 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
274
275 <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.
276 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
277 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
278
279 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
280 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
281 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
282 <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;.
283 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
284 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
285 <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.
286 <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.
287 <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.
288 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
289 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
290 </ol><p>
291
292 If you run into GCC extensions which have not been included in any of these
293 lists, please let us know (also including whether or not they work).
294
295
296<!-- _______________________________________________________________________ -->
297</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
298
299For this release, the C++ front-end is considered to be of <b>beta</b> quality.
300It works for a large number of simple programs, but has not been extensively
301tested. We welcome bug reports though!<p>
302
303<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
304 front-end</a><p>
305
306<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
307parser is significantly more standards compliant (and picky) than prior GCC
308versions. For more information, see the C++ section of the <a
309href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
310
311<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]312 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]313 function and in the <tt>setjmp</tt> receiver function may not be run.
314 Objects in intervening stack frames will be destroyed however (which is
315 better than most compilers).<p>
316
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]317<li>The LLVM C++ front-end follows the <a
318 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
319 This document, which is not Itanium specific, specifies a standard for name
320 mangling, class layout, v-table layout, RTTI formats, and other C++
321 representation issues. Because we use this API, code generated by the LLVM
322 compilers should be binary compatible with machine code generated by other
323 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
324 <i>However</i>, the exception handling mechanism used by LLVM is very
325 different from the model used in the Itanium ABI, so <b>exceptions will not
326 interact correctly</b> .
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]327
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]328<li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]329destructors when unwinding is not shared</a>.
330
331
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]332<!-- _______________________________________________________________________ -->
333</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
334
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]335<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]336href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]337support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
338or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]339
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]340
341<!-- _______________________________________________________________________ -->
342</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
343
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]344<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]345href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]346support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
347or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]348
349
350<!-- _______________________________________________________________________ -->
351</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
352
353<li>The C back-end produces code that violates the ANSI C Type-Based Alias
354Analysis rules. As such, special options may be necessary to compile the code
355(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
356problem probably cannot be fixed.<p>
357
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]358<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
359cannot include special floating point numbers like Not-A-Number or Infinity.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]360
361<li>The code produces by the C back-end has only been tested with the Sun CC and
362GCC compilers. It is possible that it will have to be adjusted to support other
363C compilers.<p>
364
365
366
367<!-- *********************************************************************** -->
368</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
369<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
370<a name="additionalinfo">Additional Information
371</b></font></td></tr></table><ul>
372<!-- *********************************************************************** -->
373
374A wide variety of additional information is available on the LLVM web page,
375including mailing lists publications describing algorithms and components
376implemented in LLVM. The web page also contains versions of the API
377documentation which is up-to-date with the CVS version of the source code. You
378can access versions of these documents specific to this release by going into
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]379the "<tt>llvm/doc/</tt>" directory in the LLVM tree.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]380
381If you have any questions or comments about LLVM, please feel free to contact us
382via the mailing lists.<p>
383
384
385<!-- *********************************************************************** -->
386</ul>
387<!-- *********************************************************************** -->
388
389<hr><font size-1>
390
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]391Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]392<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
393<!-- hhmts start -->
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]394Last modified: Mon Oct 20 14:04:51 CDT 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]395<!-- hhmts end -->
396</body></html>