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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>
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame^]67<li>CFG simplification (-simplifycfg)
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]68<li>Interprocedural dead code elimination (-globaldce)
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame^]69<li>Interprocedural constant propagation (-ipconstprop)
70<li>Dead argument elimination (-deadargelim)
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]71<li>Exception handling pruning (-prune-eh)
72<li>Function inlining (-inline)
73<li>Instruction combining (-instcombine)
74<li>Cast elimination (-raise)
75<li>Tail duplication (-tailduplicate)
76<li>CFG simplification (-simplifycfg)
77<li>Scalar replacement of aggregates (-scalarrepl)
78<li>Tail call elimination (-tailcallelim)
79<li>Instruction combining (-instcombine)
80<li>Reassociation (-reassociate)
81<li>Instruction combining (-instcombine)
82<li>CFG simplification (-simplifycfg)
Chris Lattnerd59128a2003-10-12 21:51:55 +0000[diff] [blame]83<li>Loop canonicalization (-loopsimplify)
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]84<li>Loop invariant code motion, with scalar promotion (-licm)
85<li>Global common subexpression elimination, with load elimination (-gcse)
86<li>Sparse conditional constant propagation (-sccp)
87<li>Instruction combining (-instcombine)
88<li>Induction variable canonicalization (-indvars)
89<li>Aggressive dead code elimination (-adce)
90<li>CFG simplication (-simplifycfg)
91<li>Dead type elimination (-deadtypeelim)
92<li>Global constant merging (-constmerge)
93</ol><p>
94
95At link-time, the following optimizations are run:<p>
96
97<ol>
98<li>Global constant merging (-constmerge)
99<li>[optional] Internalization [which marks most functions and global variables static] (-internalize)
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame^]100<li>Interprocedural constant propagation (-ipconstprop)
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]101<li>Interprocedural dead argument elimination (-deadargelim)
102<li>Instruction combining (-instcombine)
103<li>CFG simplification (-simplifycfg)
104<li>Interprocedural dead code elimination (-globaldce)
105</ol><p>
106
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]107At this time, LLVM is known to work properly with SPEC CPU 2000, the Olden
108benchmarks, and the Ptrdist benchmarks among many other programs. Note however
109that the Sparc and X86 backends do not currently support exception throwing or
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame^]110long jumping (including 253.perlbmk in SPEC). For these programs you must use
111the C backend.<p>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]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
Brian Gaeke15a2a252003-10-22 18:19:08 +0000[diff] [blame]121LLVM has only been extensively tested on Intel and AMD machines running Red
122Hat Linux, and Sun UltraSPARC workstations running Solaris 8.
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]123The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
124work on more platforms than that. However, it is extremely likely that we
125missed something. We welcome portability patches and error messages.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]126
127
128<!-- *********************************************************************** -->
129</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
130<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
131<a name="install-instructions">Installation Instructions
132</b></font></td></tr></table><ul>
133<!-- *********************************************************************** -->
134
135FIXME
136
137
138<!-- *********************************************************************** -->
139</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
140<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
141<a name="knownproblems">Known Problems
142</b></font></td></tr></table><ul>
143<!-- *********************************************************************** -->
144
145This section contains all known problems with the LLVM system, listed by
146component. As new problems are discovered, they will be added to these
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]147sections.
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]148
149
150<!-- _______________________________________________________________________ -->
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]151<!--
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]152</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]153-->
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]154
155
156<!-- _______________________________________________________________________ -->
157</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
158
159<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
160
161<li>The JIT does not use mutexes to protect its internal data structures. As
162 such, execution of a threaded program could cause these data structures to
163 be corrupted.<p>
164
165<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
166
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]167<li>Linking in static archive files (.a files) is very slow (there is no symbol
168table in the archive).
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame]169
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]170<!-- _______________________________________________________________________ -->
171</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
172
173<li>Inline assembly is not yet supported.<p>
174
175<li>"long double" is transformed by the front-end into "double". There is no
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]176 support for floating point data types of any size other than 32 and 64 bits.
177 <p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]178<li>C99 Variable sized arrays do not release stack memory when they go out of
179 scope. Thus, the following program may run out of stack space:
180<pre>
181 for (i = 0; i != 1000000; ++i) {
182 int X[n];
183 foo(X);
184 }
185</pre><p>
186
Chris Lattner824b9a62003-10-02 05:09:46 +0000[diff] [blame]187<li>The following Unix system functionality has not been tested and may not work:
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]188<ol>
189 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
190 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
191 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
192 - These functions have not been tested.
193</ol><p>
194
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]195<li>Bugs:<br>
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]196 <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]197<p>
198
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]199<li>Although many GCC extensions are supported, some are not. In particular,
200 the following extensions are known to <b>not be</b> supported:
201 <ol>
202 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
203 <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.
204 <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.
205 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
207 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
208 <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.
209 <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.
210 <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.
211 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
212 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
213 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
214 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
215 </ol><p>
216
217 The following GCC extensions are <b>partially</b> supported. An ignored
218 attribute means that the LLVM compiler ignores the presence of the attribute,
219 but the code should still work. An unsupported attribute is one which is
220 ignored by the LLVM compiler, which will cause a different interpretation of
221 the program.<p>
222
223 <ol>
224 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
225 Arrays whose length is computed at run time.<br>
226 Supported, but allocated stack space is not freed until the function returns (noted above).
227
228 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
229 Declaring that functions have no side effects, or that they can never return.<br>
230 <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>,
231 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
232 <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>
233 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
234 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
235 <tt>fastcall</tt>, all other target specific attributes
236
237 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
238 Specifying attributes of variables.<br>
239 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
240 <tt>deprecated</tt>, <tt>transparent_union</tt>,
241 <tt>unused</tt>, <tt>weak</tt><br>
242 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
243 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
244 <tt>vector_size</tt>, <tt>dllimport</tt>,
245 <tt>dllexport</tt>, all target specific attributes.<br>
246
247 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
248 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
249 <tt>deprecated</tt>, <tt>may_alias</tt>
250 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
251 all target specific attributes.<br>
252 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
253 Other built-in functions.<br>
254 We support all builtins which have a C language equivalent (e.g.,
255 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
256 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
257 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
258 </ol><p>
259
260
261 The following extensions <b>are</b> known to be supported:
262 <ol>
263 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
264 <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]265 <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]266 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
267 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
268 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
269 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
270 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
271 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
272 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
273 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
274 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
275 <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.
276 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
277 <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.
278 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
279
280 <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.
281 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
282 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
283
284 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
285 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
286 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
287 <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;.
288 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
289 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
290 <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.
291 <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.
292 <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.
293 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
294 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
295 </ol><p>
296
297 If you run into GCC extensions which have not been included in any of these
298 lists, please let us know (also including whether or not they work).
299
300
301<!-- _______________________________________________________________________ -->
302</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
303
304For this release, the C++ front-end is considered to be of <b>beta</b> quality.
305It works for a large number of simple programs, but has not been extensively
306tested. We welcome bug reports though!<p>
307
308<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
309 front-end</a><p>
310
311<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
312parser is significantly more standards compliant (and picky) than prior GCC
313versions. For more information, see the C++ section of the <a
314href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
315
316<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]317 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]318 function and in the <tt>setjmp</tt> receiver function may not be run.
319 Objects in intervening stack frames will be destroyed however (which is
320 better than most compilers).<p>
321
Chris Lattner19092612003-10-02 16:38:05 +0000[diff] [blame]322<li>The LLVM C++ front-end follows the <a
323 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
324 This document, which is not Itanium specific, specifies a standard for name
325 mangling, class layout, v-table layout, RTTI formats, and other C++
326 representation issues. Because we use this API, code generated by the LLVM
327 compilers should be binary compatible with machine code generated by other
328 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
329 <i>However</i>, the exception handling mechanism used by LLVM is very
330 different from the model used in the Itanium ABI, so <b>exceptions will not
331 interact correctly</b> .
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]332
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]333<li><a href="http://llvm.cs.uiuc.edu/PR11">Code for executing
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]334destructors when unwinding is not shared</a>.
335
336
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]337<!-- _______________________________________________________________________ -->
338</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
339
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]340<li>The X86 code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]341href="http://llvm.cs.uiuc.edu/PR16">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]342support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
343or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]344
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]345
346<!-- _______________________________________________________________________ -->
347</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
348
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]349<li>The Sparc code generator <a
Chris Lattner0d4379a2003-10-08 06:01:38 +0000[diff] [blame]350href="http://llvm.cs.uiuc.edu/PR15">does not currently
Chris Lattnerfcc54b32003-10-07 22:14:37 +0000[diff] [blame]351support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
352or calls the C <tt>longjmp</tt> function will abort.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]353
354
355<!-- _______________________________________________________________________ -->
356</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
357
358<li>The C back-end produces code that violates the ANSI C Type-Based Alias
359Analysis rules. As such, special options may be necessary to compile the code
360(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
361problem probably cannot be fixed.<p>
362
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]363<li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
364cannot include special floating point numbers like Not-A-Number or Infinity.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]365
Chris Lattner2af46052003-10-24 04:03:19 +0000[diff] [blame^]366<li><a href="http://zion.cs.uiuc.edu/PR56">Zero arg vararg functions are not
367supported</a>. This should not affect LLVM produced by the C or C++
368frontends.<p>
369
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]370<li>The code produces by the C back-end has only been tested with the Sun CC and
371GCC compilers. It is possible that it will have to be adjusted to support other
372C compilers.<p>
373
374
375
376<!-- *********************************************************************** -->
377</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
378<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
379<a name="additionalinfo">Additional Information
380</b></font></td></tr></table><ul>
381<!-- *********************************************************************** -->
382
383A wide variety of additional information is available on the LLVM web page,
384including mailing lists publications describing algorithms and components
385implemented in LLVM. The web page also contains versions of the API
386documentation which is up-to-date with the CVS version of the source code. You
387can access versions of these documents specific to this release by going into
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]388the "<tt>llvm/doc/</tt>" directory in the LLVM tree.<p>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]389
390If you have any questions or comments about LLVM, please feel free to contact us
391via the mailing lists.<p>
392
393
394<!-- *********************************************************************** -->
395</ul>
396<!-- *********************************************************************** -->
397
398<hr><font size-1>
399
Chris Lattner47ad72c2003-10-07 21:38:31 +0000[diff] [blame]400Maintained By: <a href="http://llvm.cs.uiuc.edu/">The LLVM Team</a><br>
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]401<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
402<!-- hhmts start -->
Chris Lattnere84843b2003-10-20 19:05:03 +0000[diff] [blame]403Last modified: Mon Oct 20 14:04:51 CDT 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]404<!-- hhmts end -->
405</body></html>