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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>
10 <li><a href="#intro">Instroduction</a>
11 <li><a href="#whatsnew">What's New?</a>
12 <li><a href="#install-instructions">Installation Instructions</a>
13 <li><a href="#knownproblems">Known Problems</a>
14 <ul>
15 <li><a href="#portability">Portability Problems</a>
16 <li><a href="#core">Known problems with the LLVM Core</a>
17 <li><a href="#c-fe">Known problems with the C Front-end</a>
18 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
19 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
20 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
21 <li><a href="#c-be">Known problems with the C back-end</a>
22 </ul>
23 <li><a href="#additionalinfo">Additional Information</a>
24 </ul>
25
26 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
27</ol>
28
29
30<!-- *********************************************************************** -->
31<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
32<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
33<a name="intro">Introduction
34</b></font></td></tr></table><ul>
35<!-- *********************************************************************** -->
36
37This document contains the release notes for the LLVM compiler infrastructure,
38release 1.0. The most up-to-date version of this document can be found on the
39<a href="http://llvm.cs.uiuc.edu/releases/1.0/ReleaseNotes.html">LLVM web
40site</a>. Since this document may be updated after the release, it is best to
41read the copy hosted there.
42
43
44<!-- *********************************************************************** -->
45</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
46<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
47<a name="whatsnew">What's New?
48</b></font></td></tr></table><ul>
49<!-- *********************************************************************** -->
50
51This is the first public release of the LLVM compiler infrastructure. As such,
52it is all new! In particular, we are providing a stable C compiler, beta C++
53compiler, a C back-end, stable X86 and Sparc V9 static and JIT code generators,
54as well as a large suite of scalar and interprocedural optimizations.<p>
55
56TODO: Works on: SPEC CPU 2000<p>
57TODO: Works on: Olden/Ptrdist benchmarks
58
59
60<!-- *********************************************************************** -->
61</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
62<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
63<a name="install-instructions">Installation Instructions
64</b></font></td></tr></table><ul>
65<!-- *********************************************************************** -->
66
67FIXME
68
69
70<!-- *********************************************************************** -->
71</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
72<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
73<a name="knownproblems">Known Problems
74</b></font></td></tr></table><ul>
75<!-- *********************************************************************** -->
76
77This section contains all known problems with the LLVM system, listed by
78component. As new problems are discovered, they will be added to these
79sections, so it is important to check the <a
80href="http://llvm.cs.uiuc.edu/releases/1.0/ReleaseNotes.html">web version</a> of
81this document for up-to-date information.
82
83
84<!-- _______________________________________________________________________ -->
85</ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
86
87LLVM has only been extensively tested on ia32-linux and sparc-solaris machines.
88The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
89work on more platforms than that. However, it is extremely likely that we
90missed something. We welcome portability patches and error messages.<p>
91
92
93<!-- _______________________________________________________________________ -->
94</ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
95
96<li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
97
98<li>The JIT does not use mutexes to protect its internal data structures. As
99 such, execution of a threaded program could cause these data structures to
100 be corrupted.<p>
101
102<li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
103
104<!-- _______________________________________________________________________ -->
105</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
106
107<li>Inline assembly is not yet supported.<p>
108
109<li>"long double" is transformed by the front-end into "double". There is no
110 support for floating point data types of any size other than 32 and 64 bits.
111 <p>
112<li>C99 Variable sized arrays do not release stack memory when they go out of
113 scope. Thus, the following program may run out of stack space:
114<pre>
115 for (i = 0; i != 1000000; ++i) {
116 int X[n];
117 foo(X);
118 }
119</pre><p>
120
121<li>The following unix system functionality has not been tested and may not work:
122<ol>
123 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
124 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
125 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
126 - These functions have not been tested.
127</ol><p>
128
129<li>Although many GCC extensions are supported, some are not. In particular,
130 the following extensions are known to <b>not be</b> supported:
131 <ol>
132 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
133 <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.
134 <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.
135 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
136 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
137 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
138 <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.
139 <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.
140 <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.
141 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
142 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
143 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
144 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
145 </ol><p>
146
147 The following GCC extensions are <b>partially</b> supported. An ignored
148 attribute means that the LLVM compiler ignores the presence of the attribute,
149 but the code should still work. An unsupported attribute is one which is
150 ignored by the LLVM compiler, which will cause a different interpretation of
151 the program.<p>
152
153 <ol>
154 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
155 Arrays whose length is computed at run time.<br>
156 Supported, but allocated stack space is not freed until the function returns (noted above).
157
158 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
159 Declaring that functions have no side effects, or that they can never return.<br>
160 <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>,
161 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
162 <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>
163 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
164 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
165 <tt>fastcall</tt>, all other target specific attributes
166
167 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
168 Specifying attributes of variables.<br>
169 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
170 <tt>deprecated</tt>, <tt>transparent_union</tt>,
171 <tt>unused</tt>, <tt>weak</tt><br>
172 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
173 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
174 <tt>vector_size</tt>, <tt>dllimport</tt>,
175 <tt>dllexport</tt>, all target specific attributes.<br>
176
177 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
178 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
179 <tt>deprecated</tt>, <tt>may_alias</tt>
180 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
181 all target specific attributes.<br>
182 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
183 Other built-in functions.<br>
184 We support all builtins which have a C language equivalent (e.g.,
185 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
186 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
187 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
188 </ol><p>
189
190
191 The following extensions <b>are</b> known to be supported:
192 <ol>
193 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
194 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
195 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, <code>,</code> and casts in lvalues.
196 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
197 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
198 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
199 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
200 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
202 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
203 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
204 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
205 <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.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
207 <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.
208 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
209
210 <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.
211 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
212 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
213
214 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
215 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
216 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
217 <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;.
218 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
219 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
220 <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.
221 <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.
222 <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.
223 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
224 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
225 </ol><p>
226
227 If you run into GCC extensions which have not been included in any of these
228 lists, please let us know (also including whether or not they work).
229
230
231<!-- _______________________________________________________________________ -->
232</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
233
234For this release, the C++ front-end is considered to be of <b>beta</b> quality.
235It works for a large number of simple programs, but has not been extensively
236tested. We welcome bug reports though!<p>
237
238<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
239 front-end</a><p>
240
241<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
242parser is significantly more standards compliant (and picky) than prior GCC
243versions. For more information, see the C++ section of the <a
244href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
245
246<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
247 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
248 function and in the <tt>setjmp</tt> receiver function may not be run.
249 Objects in intervening stack frames will be destroyed however (which is
250 better than most compilers).<p>
251
252<li>The calling conventions and name mangling used by the LLVM C++ front-end do
253 follow the <a href="http://www.codesourcery.com/cxx-abi">Itanium C++
254 ABI</a>, and thus we should be binary compatible with native C++ code
255 compiled with a recent GCC compiler. However, the exception handling
256 mechanisms are very different, so they will not interact correctly.
257
258<!-- _______________________________________________________________________ -->
259</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
260
261<li>The X86 code generator does not currently support the <tt>unwind</tt>
262instruction, so code that throws a C++ exception or calls the C <tt>longjmp</tt>
263function will abort.<p>
264
265<li>Some executables produced by LLC seem to intermittently crash (extremely
266infrequently). The cause of the problem has not been diagnosed, and does not
267affect the JIT.<p>
268
269
270<!-- _______________________________________________________________________ -->
271</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
272
273<li>The Sparc code generator does not currently support the <tt>invoke</tt> or
274<tt>unwind</tt> instructions, so code produced by the C++ front-end and C code
275that calls the <tt>setjmp</tt> or <tt>longjmp</tt> functions will not compile.
276
277
278<!-- _______________________________________________________________________ -->
279</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
280
281<li>The C back-end produces code that violates the ANSI C Type-Based Alias
282Analysis rules. As such, special options may be necessary to compile the code
283(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
284problem probably cannot be fixed.<p>
285
286<li>Initializers for global variables that include floating point numbers may
287not be initialized with exactly the right floating point number, if the number
288is not accurately representable in decimal. This prevents the Olden "power"
289benchmark from producing exactly the right results with the C backend.<p>
290
291<li>The code produces by the C back-end has only been tested with the Sun CC and
292GCC compilers. It is possible that it will have to be adjusted to support other
293C compilers.<p>
294
295
296
297<!-- *********************************************************************** -->
298</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
299<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
300<a name="additionalinfo">Additional Information
301</b></font></td></tr></table><ul>
302<!-- *********************************************************************** -->
303
304A wide variety of additional information is available on the LLVM web page,
305including mailing lists publications describing algorithms and components
306implemented in LLVM. The web page also contains versions of the API
307documentation which is up-to-date with the CVS version of the source code. You
308can access versions of these documents specific to this release by going into
309the "<tt>llvm/www/doc/</tt>" directory in the LLVM tree.<p>
310
311If you have any questions or comments about LLVM, please feel free to contact us
312via the mailing lists.<p>
313
314
315<!-- *********************************************************************** -->
316</ul>
317<!-- *********************************************************************** -->
318
319<hr><font size-1>
320
321<address>By: <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
322<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
323<!-- hhmts start -->
324Last modified: Wed Oct 1 23:56:16 CDT 2003
325<!-- hhmts end -->
326</body></html>