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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
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame^]104<li>Linking in static archive files (.a files) is very slow.
105
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]106<!-- _______________________________________________________________________ -->
107</ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
108
109<li>Inline assembly is not yet supported.<p>
110
111<li>"long double" is transformed by the front-end into "double". There is no
112 support for floating point data types of any size other than 32 and 64 bits.
113 <p>
114<li>C99 Variable sized arrays do not release stack memory when they go out of
115 scope. Thus, the following program may run out of stack space:
116<pre>
117 for (i = 0; i != 1000000; ++i) {
118 int X[n];
119 foo(X);
120 }
121</pre><p>
122
123<li>The following unix system functionality has not been tested and may not work:
124<ol>
125 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
126 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
127 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
128 - These functions have not been tested.
129</ol><p>
130
131<li>Although many GCC extensions are supported, some are not. In particular,
132 the following extensions are known to <b>not be</b> supported:
133 <ol>
134 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
135 <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.
136 <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.
137 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
138 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
139 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
140 <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.
141 <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.
142 <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.
143 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
144 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
145 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
146 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
147 </ol><p>
148
149 The following GCC extensions are <b>partially</b> supported. An ignored
150 attribute means that the LLVM compiler ignores the presence of the attribute,
151 but the code should still work. An unsupported attribute is one which is
152 ignored by the LLVM compiler, which will cause a different interpretation of
153 the program.<p>
154
155 <ol>
156 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
157 Arrays whose length is computed at run time.<br>
158 Supported, but allocated stack space is not freed until the function returns (noted above).
159
160 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
161 Declaring that functions have no side effects, or that they can never return.<br>
162 <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>,
163 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
164 <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>
165 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
166 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
167 <tt>fastcall</tt>, all other target specific attributes
168
169 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
170 Specifying attributes of variables.<br>
171 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
172 <tt>deprecated</tt>, <tt>transparent_union</tt>,
173 <tt>unused</tt>, <tt>weak</tt><br>
174 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
175 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
176 <tt>vector_size</tt>, <tt>dllimport</tt>,
177 <tt>dllexport</tt>, all target specific attributes.<br>
178
179 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
180 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
181 <tt>deprecated</tt>, <tt>may_alias</tt>
182 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
183 all target specific attributes.<br>
184 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
185 Other built-in functions.<br>
186 We support all builtins which have a C language equivalent (e.g.,
187 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
188 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
189 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
190 </ol><p>
191
192
193 The following extensions <b>are</b> known to be supported:
194 <ol>
195 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
196 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
197 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, <code>,</code> and casts in lvalues.
198 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
199 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
200 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
202 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
203 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
204 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
205 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
206 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
207 <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.
208 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
209 <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.
210 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
211
212 <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.
213 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
214 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
215
216 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
217 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
218 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
219 <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;.
220 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
221 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
222 <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.
223 <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.
224 <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.
225 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
226 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
227 </ol><p>
228
229 If you run into GCC extensions which have not been included in any of these
230 lists, please let us know (also including whether or not they work).
231
232
233<!-- _______________________________________________________________________ -->
234</ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
235
236For this release, the C++ front-end is considered to be of <b>beta</b> quality.
237It works for a large number of simple programs, but has not been extensively
238tested. We welcome bug reports though!<p>
239
240<li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
241 front-end</a><p>
242
243<li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
244parser is significantly more standards compliant (and picky) than prior GCC
245versions. For more information, see the C++ section of the <a
246href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
247
248<li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
249 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
250 function and in the <tt>setjmp</tt> receiver function may not be run.
251 Objects in intervening stack frames will be destroyed however (which is
252 better than most compilers).<p>
253
254<li>The calling conventions and name mangling used by the LLVM C++ front-end do
255 follow the <a href="http://www.codesourcery.com/cxx-abi">Itanium C++
256 ABI</a>, and thus we should be binary compatible with native C++ code
257 compiled with a recent GCC compiler. However, the exception handling
258 mechanisms are very different, so they will not interact correctly.
259
260<!-- _______________________________________________________________________ -->
261</ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
262
263<li>The X86 code generator does not currently support the <tt>unwind</tt>
264instruction, so code that throws a C++ exception or calls the C <tt>longjmp</tt>
265function will abort.<p>
266
267<li>Some executables produced by LLC seem to intermittently crash (extremely
268infrequently). The cause of the problem has not been diagnosed, and does not
269affect the JIT.<p>
270
271
272<!-- _______________________________________________________________________ -->
273</ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
274
275<li>The Sparc code generator does not currently support the <tt>invoke</tt> or
276<tt>unwind</tt> instructions, so code produced by the C++ front-end and C code
277that calls the <tt>setjmp</tt> or <tt>longjmp</tt> functions will not compile.
278
279
280<!-- _______________________________________________________________________ -->
281</ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
282
283<li>The C back-end produces code that violates the ANSI C Type-Based Alias
284Analysis rules. As such, special options may be necessary to compile the code
285(for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
286problem probably cannot be fixed.<p>
287
288<li>Initializers for global variables that include floating point numbers may
289not be initialized with exactly the right floating point number, if the number
290is not accurately representable in decimal. This prevents the Olden "power"
291benchmark from producing exactly the right results with the C backend.<p>
292
293<li>The code produces by the C back-end has only been tested with the Sun CC and
294GCC compilers. It is possible that it will have to be adjusted to support other
295C compilers.<p>
296
297
298
299<!-- *********************************************************************** -->
300</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
301<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
302<a name="additionalinfo">Additional Information
303</b></font></td></tr></table><ul>
304<!-- *********************************************************************** -->
305
306A wide variety of additional information is available on the LLVM web page,
307including mailing lists publications describing algorithms and components
308implemented in LLVM. The web page also contains versions of the API
309documentation which is up-to-date with the CVS version of the source code. You
310can access versions of these documents specific to this release by going into
311the "<tt>llvm/www/doc/</tt>" directory in the LLVM tree.<p>
312
313If you have any questions or comments about LLVM, please feel free to contact us
314via the mailing lists.<p>
315
316
317<!-- *********************************************************************** -->
318</ul>
319<!-- *********************************************************************** -->
320
321<hr><font size-1>
322
323<address>By: <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
324<!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
325<!-- hhmts start -->
Chris Lattner47588f92003-10-02 05:07:23 +0000[diff] [blame^]326Last modified: Thu Oct 2 00:06:58 CDT 2003
Chris Lattner79c3fe12003-10-02 04:57:28 +0000[diff] [blame]327<!-- hhmts end -->
328</body></html>