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2 <html><head><title>LLVM 1.0 Release Notes</title></head>
5 <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
6 <tr><td> <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM 1.0 Release Notes</b></font></td>
10 <li><a href="#intro">Introduction</a>
11 <li><a href="#whatsnew">What's New?</a>
12 <li><a href="#portability">Portability and Supported Platforms</a>
13 <li><a href="#install-instructions">Installation Instructions</a>
14 <li><a href="#knownproblems">Known Problems</a>
16 <!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
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>
24 <li><a href="#additionalinfo">Additional Information</a>
27 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
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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 <!-- *********************************************************************** -->
38 This document contains the release notes for the LLVM compiler infrastructure,
39 release 1.0. The most up-to-date version of this document can be found on the
40 <a href="http://llvm.cs.uiuc.edu/releases/1.0/ReleaseNotes.html">LLVM web
41 site</a>. If you are not reading this on the LLVM web pages, you should
42 probably go there, because this document may be updated after the release.<p>
44 FIXME: What is this document? Where do I find other documents?<p>
47 <!-- *********************************************************************** -->
48 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
49 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
50 <a name="whatsnew">What's New?
51 </b></font></td></tr></table><ul>
52 <!-- *********************************************************************** -->
54 This is the first public release of the LLVM compiler infrastructure. As such,
55 it is all new! In particular, we are providing a stable C compiler, beta C++
56 compiler, a C back-end, stable X86 and Sparc V9 static and JIT code generators,
57 as well as a large suite of scalar and interprocedural optimizations.<p>
59 TODO: Works on: SPEC CPU 2000<p>
60 TODO: Works on: Olden/Ptrdist benchmarks<p>
62 The What's New section should give a bulletted list of what is
63 included, perhaps a couple of lists (Stable, Beta).<p>
65 It would be useful to give a pointer to a list of the available passes (at least
66 for the standard compiler techniques).<p>
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70 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
71 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
72 <a name="portability">Portability and Supported Platforms
73 </b></font></td></tr></table><ul>
74 <!-- *********************************************************************** -->
76 LLVM has only been extensively tested on ia32-linux and sparc-solaris machines.
77 The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
78 work on more platforms than that. However, it is extremely likely that we
79 missed something. We welcome portability patches and error messages.<p>
82 <!-- *********************************************************************** -->
83 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
84 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
85 <a name="install-instructions">Installation Instructions
86 </b></font></td></tr></table><ul>
87 <!-- *********************************************************************** -->
92 <!-- *********************************************************************** -->
93 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
94 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
95 <a name="knownproblems">Known Problems
96 </b></font></td></tr></table><ul>
97 <!-- *********************************************************************** -->
99 This section contains all known problems with the LLVM system, listed by
100 component. As new problems are discovered, they will be added to these
104 <!-- _______________________________________________________________________ -->
106 </ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
110 <!-- _______________________________________________________________________ -->
111 </ul><h4><a name="core"><hr size=0>Known problems with the LLVM Core</h4><ul>
113 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.<p>
115 <li>The JIT does not use mutexes to protect its internal data structures. As
116 such, execution of a threaded program could cause these data structures to
119 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.<p>
121 <li>Linking in static archive files (.a files) is very slow.
123 <!-- _______________________________________________________________________ -->
124 </ul><h4><a name="c-fe"><hr size=0>Known problems with the C front-end</h4><ul>
126 <li>Inline assembly is not yet supported.<p>
128 <li>"long double" is transformed by the front-end into "double". There is no
129 support for floating point data types of any size other than 32 and 64 bits.
131 <li>C99 Variable sized arrays do not release stack memory when they go out of
132 scope. Thus, the following program may run out of stack space:
134 for (i = 0; i != 1000000; ++i) {
140 <li>The following Unix system functionality has not been tested and may not work:
142 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
143 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions.
144 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
145 - These functions have not been tested.
148 <li>Although many GCC extensions are supported, some are not. In particular,
149 the following extensions are known to <b>not be</b> supported:
151 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.
152 <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.
153 <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.
154 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.
155 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.
156 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands
157 <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.
158 <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.
159 <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.
160 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.
161 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.
162 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.
163 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.
166 The following GCC extensions are <b>partially</b> supported. An ignored
167 attribute means that the LLVM compiler ignores the presence of the attribute,
168 but the code should still work. An unsupported attribute is one which is
169 ignored by the LLVM compiler, which will cause a different interpretation of
173 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
174 Arrays whose length is computed at run time.<br>
175 Supported, but allocated stack space is not freed until the function returns (noted above).
177 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
178 Declaring that functions have no side effects, or that they can never return.<br>
179 <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>,
180 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
181 <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>
182 <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
183 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>, <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
184 <tt>fastcall</tt>, all other target specific attributes
186 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
187 Specifying attributes of variables.<br>
188 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
189 <tt>deprecated</tt>, <tt>transparent_union</tt>,
190 <tt>unused</tt>, <tt>weak</tt><br>
191 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
192 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
193 <tt>vector_size</tt>, <tt>dllimport</tt>,
194 <tt>dllexport</tt>, all target specific attributes.<br>
196 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.
197 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
198 <tt>deprecated</tt>, <tt>may_alias</tt>
199 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>
200 all target specific attributes.<br>
201 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
202 Other built-in functions.<br>
203 We support all builtins which have a C language equivalent (e.g.,
204 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
205 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
206 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).
210 The following extensions <b>are</b> known to be supported:
212 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.
213 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.
214 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.
215 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.
216 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.
217 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.
218 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.
219 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.
220 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.
221 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.
222 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.
223 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.
224 <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.
225 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.
226 <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.
227 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.
229 <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.
230 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.
231 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.
233 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.
234 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.
235 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.
236 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Character-Escapes.html#Character%20Escapes">Character Escapes</a>: <code>\e</code> stands for the character <ESC>.
237 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.
238 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).
239 <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.
240 <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.
241 <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.
242 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.
243 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.
246 If you run into GCC extensions which have not been included in any of these
247 lists, please let us know (also including whether or not they work).
250 <!-- _______________________________________________________________________ -->
251 </ul><h4><a name="c++-fe"><hr size=0>Known problems with the C++ front-end</h4><ul>
253 For this release, the C++ front-end is considered to be of <b>beta</b> quality.
254 It works for a large number of simple programs, but has not been extensively
255 tested. We welcome bug reports though!<p>
257 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
260 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
261 parser is significantly more standards compliant (and picky) than prior GCC
262 versions. For more information, see the C++ section of the <a
263 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.<p>
265 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
266 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
267 function and in the <tt>setjmp</tt> receiver function may not be run.
268 Objects in intervening stack frames will be destroyed however (which is
269 better than most compilers).<p>
271 <li>The LLVM C++ front-end follows the <a
272 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
273 This document, which is not Itanium specific, specifies a standard for name
274 mangling, class layout, v-table layout, RTTI formats, and other C++
275 representation issues. Because we use this API, code generated by the LLVM
276 compilers should be binary compatible with machine code generated by other
277 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
278 <i>However</i>, the exception handling mechanism used by LLVM is very
279 different from the model used in the Itanium ABI, so <b>exceptions will not
280 interact correctly</b> .
282 <!-- _______________________________________________________________________ -->
283 </ul><h4><a name="x86-be"><hr size=0>Known problems with the X86 back-end</h4><ul>
285 <li>The X86 code generator does not currently support the <tt>unwind</tt>
286 instruction, so code that throws a C++ exception or calls the C <tt>longjmp</tt>
287 function will abort.<p>
289 <li>Some executables produced by LLC seem to intermittently crash (extremely
290 infrequently). The cause of the problem has not been diagnosed, and does not
294 <!-- _______________________________________________________________________ -->
295 </ul><h4><a name="sparc-be"><hr size=0>Known problems with the Sparc back-end</h4><ul>
297 <li>The Sparc code generator does not currently support the <tt>invoke</tt> or
298 <tt>unwind</tt> instructions, so code produced by the C++ front-end and C code
299 that calls the <tt>setjmp</tt> or <tt>longjmp</tt> functions will not compile.
302 <!-- _______________________________________________________________________ -->
303 </ul><h4><a name="c-be"><hr size=0>Known problems with the C back-end</h4><ul>
305 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
306 Analysis rules. As such, special options may be necessary to compile the code
307 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
308 problem probably cannot be fixed.<p>
310 <li>Initializers for global variables that include floating point numbers may
311 not be initialized with exactly the right floating point number, if the number
312 is not accurately representable in decimal. This prevents the Olden "power"
313 benchmark from producing exactly the right results with the C back-end.<p>
315 <li>The code produces by the C back-end has only been tested with the Sun CC and
316 GCC compilers. It is possible that it will have to be adjusted to support other
321 <!-- *********************************************************************** -->
322 </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
323 <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
324 <a name="additionalinfo">Additional Information
325 </b></font></td></tr></table><ul>
326 <!-- *********************************************************************** -->
328 A wide variety of additional information is available on the LLVM web page,
329 including mailing lists publications describing algorithms and components
330 implemented in LLVM. The web page also contains versions of the API
331 documentation which is up-to-date with the CVS version of the source code. You
332 can access versions of these documents specific to this release by going into
333 the "<tt>llvm/www/doc/</tt>" directory in the LLVM tree.<p>
335 If you have any questions or comments about LLVM, please feel free to contact us
336 via the mailing lists.<p>
339 <!-- *********************************************************************** -->
341 <!-- *********************************************************************** -->
345 <address>By: <a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
346 <!-- Created: Wed Oct 1 17:38:54 CDT 2003 -->
348 Last modified: Thu Oct 2 11:37:25 CDT 2003