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6 <title>LLVM 1.2 Release Notes</title>
10 <div class="doc_title">
11 LLVM 1.2 Release Notes
15 <li><a href="#intro">Introduction</a></li>
16 <li><a href="#whatsnew">What's New?</a></li>
17 <li><a href="#portability">Portability and Supported Platforms</a></li>
18 <li><a href="#install-instructions">Installation Instructions</a></li>
19 <li><a href="#knownproblems">Known Problems</a>
21 <!-- <li><a href="#portabilityprobs">Portability Problems</a> -->
22 <li><a href="#core">Known problems with the LLVM Core</a>
23 <li><a href="#c-fe">Known problems with the C Front-end</a>
24 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
25 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
26 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
27 <li><a href="#c-be">Known problems with the C back-end</a>
29 <li><a href="#additionalinfo">Additional Information</a></li>
32 <div class="doc_text">
33 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p>
36 <!-- *********************************************************************** -->
37 <div class="doc_section">
38 <a name="intro">Introduction</a>
40 <!-- *********************************************************************** -->
42 <div class="doc_text">
44 <p>This document contains the release notes for the LLVM compiler
45 infrastructure, release 1.2. Here we describe the status of LLVM, including any
46 known problems, and bug fixes from the previous release. The most up-to-date
47 version of this document can be found on the <a
48 href="http://llvm.cs.uiuc.edu/releases/1.2/">LLVM 1.2 web site</a>. If you are
49 not reading this on the LLVM web pages, you should probably go there, because
50 this document may be updated after the release.</p>
52 <p>For more information about LLVM, including information about potentially more
53 current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
54 web site</a>. If you have questions or comments, the <a
55 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
56 list</a> is a good place to send them.</p>
58 <p>Note that if you are reading this file from CVS, this document applies
59 to the <i>next</i> release, not the current one. To see the release notes for
60 the current or previous releases, see the <a
61 href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
65 <!-- *********************************************************************** -->
66 <div class="doc_section">
67 <a name="whatsnew">What's New?</a>
69 <!-- *********************************************************************** -->
71 <div class="doc_text">
73 <p>This is the third public release of the LLVM compiler infrastructure. OTHER
77 <p>At this time, LLVM is known to correctly compile and run all non-unwinding C
78 & C++ SPEC CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist
79 benchmarks. It has also been used to compile <b>many</b> other programs. LLVM
80 now also works with a broad variety of C++ programs, though it has still
81 received much less testing than the C front-end.
85 The LLVM native code generators are very stable, but do not currently support
86 unwinding (exception throwing or <tt>longjmp</tt>ing), which prevent them from
87 working with programs like the <tt>253.perlbmk</tt> in SPEC CPU2000. The C
88 backend and the rest of LLVM does support these programs however, so you can
89 still use LLVM with them. Support for unwinding will be added in a future
94 <!--=========================================================================-->
95 <div class="doc_subsubsection">
96 This release implements the following new features:
105 <!--=========================================================================-->
106 <div class="doc_subsubsection">
107 In this release, the following missing features were implemented:
116 <!--=========================================================================-->
117 <div class="doc_subsubsection">
118 In this release, the following Quality of Implementation issues were
130 <!--=========================================================================-->
131 <div class="doc_subsubsection">
132 In this release, the following bugs in the previous release were fixed:
135 <p>Bugs in the LLVM Core:</p>
138 <li><a href="http://llvm.cs.uiuc.edu/PR179">[licm] LICM promotes volatile memory
139 locations to registers</a></li>
144 <p>Bugs in the C/C++ front-end:</p>
147 <li><a href="http://llvm.cs.uiuc.edu/PR186">Need weak linkage on memory
148 management functions in libc runtime to allow them to be overriden</a></li>
154 <!-- *********************************************************************** -->
155 <div class="doc_section">
156 <a name="portability">Portability and Supported Platforms</a>
158 <!-- *********************************************************************** -->
160 <div class="doc_text">
162 <p>LLVM has been extensively tested on Intel and AMD machines running Red
163 Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations running Solaris 8.
165 LLVM works on Mac OS/X 10.3 and above, but only with the C backend or
166 interpreter (no native backend for the PowerPC is available yet).
167 The core LLVM infrastructure uses "autoconf" for portability, so hopefully we
168 work on more platforms than that. However, it is likely that we
169 missed something, and that minor porting is required to get LLVM to work on
170 new platforms. We welcome portability patches and error messages.</p>
174 <!-- *********************************************************************** -->
175 <div class="doc_section">
176 <a name="knownproblems">Known Problems</a>
178 <!-- *********************************************************************** -->
180 <div class="doc_text">
182 <p>This section contains all known problems with the LLVM system, listed by
183 component. As new problems are discovered, they will be added to these
184 sections. If you run into a problem, please check the <a
185 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a>, and submit a bug if
186 there isn't already one.</p>
190 <!-- _______________________________________________________________________ -->
192 </ul><h4><a name="portability"><hr size=0>Portability Problems</h4><ul>
196 <!-- ======================================================================= -->
197 <div class="doc_subsection">
198 <a name="core">Known problems with the LLVM Core</a>
201 <div class="doc_text">
205 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
208 <li>The JIT does not use mutexes to protect its internal data structures. As
209 such, execution of a threaded program could cause these data structures to be
212 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
214 <li>Linking in static archive files (.a files) is very slow (there is no symbol
215 table in the archive).</li>
217 <li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
218 more than 256 elements</a>.</li>
224 <!-- ======================================================================= -->
225 <div class="doc_subsection">
226 <a name="c-fe">Known problems with the C front-end</a>
229 <!-- _______________________________________________________________________ -->
230 <div class="doc_subsubsection">Bugs</div>
232 <div class="doc_text">
236 <li>C99 Variable sized arrays do not release stack memory when they go out of
237 scope. Thus, the following program may run out of stack space:
239 for (i = 0; i != 1000000; ++i) {
249 <!-- _______________________________________________________________________ -->
250 <div class="doc_subsubsection">
254 <div class="doc_text">
258 <li>Inline assembly is not yet supported.</li>
260 <li>"long double" is transformed by the front-end into "double". There is no
261 support for floating point data types of any size other than 32 and 64
264 <li>The following Unix system functionality has not been tested and may not
267 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
268 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
269 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
270 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
271 - These functions have not been tested.
274 <li>Although many GCC extensions are supported, some are not. In particular,
275 the following extensions are known to <b>not be</b> supported:
277 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
278 <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.</li>
279 <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.</li>
280 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
281 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Extended%20Asm">Extended Asm</a>: Assembler instructions with C expressions as operands.</li>
282 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands</li>
283 <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.</li>
284 <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.</li>
285 <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.</li>
286 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Vector-Extensions.html#Vector%20Extensions">Vector Extensions</a>: Using vector instructions through built-in functions.</li>
287 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Target-Builtins.html#Target%20Builtins">Target Builtins</a>: Built-in functions specific to particular targets.</li>
288 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
289 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
292 <p>The following GCC extensions are <b>partially</b> supported. An ignored
293 attribute means that the LLVM compiler ignores the presence of the attribute,
294 but the code should still work. An unsupported attribute is one which is
295 ignored by the LLVM compiler, which will cause a different interpretation of
299 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
300 Arrays whose length is computed at run time.<br>
301 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
303 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
305 Declaring that functions have no side effects, or that they can never
308 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
309 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
310 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
312 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
313 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
314 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
316 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
317 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
318 <tt>fastcall</tt>, all other target specific attributes</li>
320 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
321 Specifying attributes of variables.<br>
322 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
323 <tt>deprecated</tt>, <tt>transparent_union</tt>,
324 <tt>unused</tt>, <tt>weak</tt><br>
326 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
327 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
328 <tt>vector_size</tt>, <tt>dllimport</tt>,
329 <tt>dllexport</tt>, all target specific attributes.</li>
331 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
332 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
333 <tt>deprecated</tt>, <tt>may_alias</tt><br>
335 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
336 all target specific attributes.</li>
338 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
339 Other built-in functions.<br>
340 We support all builtins which have a C language equivalent (e.g.,
341 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
342 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
343 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
347 <p>The following extensions <b>are</b> known to be supported:</p>
350 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
351 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Typeof.html#Typeof">Typeof</a>: <code>typeof</code>: referring to the type of an expression.</li>
352 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
353 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
354 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
355 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
356 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
357 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
358 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
359 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variadic-Macros.html#Variadic%20Macros">Variadic Macros</a>: Macros with a variable number of arguments.</li>
360 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
361 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Subscripting.html#Subscripting">Subscripting</a>: Any array can be subscripted, even if not an lvalue.</li>
362 <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.</li>
363 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
364 <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.</li>
365 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
366 <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.</li>
367 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
368 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
369 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
370 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
371 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
372 <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>.</li>
373 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
374 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
375 <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.</li>
376 <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.</li>
377 <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.</li>
378 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Unnamed-Fields.html#Unnamed%20Fields">Unnamed Fields</a>: Unnamed struct/union fields within structs/unions.</li>
379 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
384 <p>If you run into GCC extensions which have not been included in any of these
385 lists, please let us know (also including whether or not they work).</p>
389 <!-- ======================================================================= -->
390 <div class="doc_subsection">
391 <a name="c++-fe">Known problems with the C++ front-end</a>
394 <div class="doc_text">
396 <p>For this release, the C++ front-end is considered to be fully functional, but
397 has not been tested as thoroughly as the C front-end. It has been tested and
398 works for a number of non-trivial programs, but there may be lurking bugs.
399 Please report any bugs or problems.</p>
403 <!-- _______________________________________________________________________ -->
404 <div class="doc_subsubsection">
408 <div class="doc_text">
411 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
417 <!-- _______________________________________________________________________ -->
418 <div class="doc_subsubsection">
422 <div class="doc_text">
426 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
427 parser is significantly more standards compliant (and picky) than prior GCC
428 versions. For more information, see the C++ section of the <a
429 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
431 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
432 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
433 function and in the <tt>setjmp</tt> receiver function may not be run.
434 Objects in intervening stack frames will be destroyed however (which is
435 better than most compilers).</li>
437 <li>The LLVM C++ front-end follows the <a
438 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
439 This document, which is not Itanium specific, specifies a standard for name
440 mangling, class layout, v-table layout, RTTI formats, and other C++
441 representation issues. Because we use this API, code generated by the LLVM
442 compilers should be binary compatible with machine code generated by other
443 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
444 <i>However</i>, the exception handling mechanism used by LLVM is very
445 different from the model used in the Itanium ABI, so <b>exceptions will not
446 interact correctly</b>. </li>
452 <!-- ======================================================================= -->
453 <div class="doc_subsection">
454 <a name="x86-be">Known problems with the X86 back-end</a>
457 <div class="doc_text">
461 <li>The X86 code generator <a
462 href="http://llvm.cs.uiuc.edu/PR16">does not currently
463 support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
464 or calls the C <tt>longjmp</tt> function will abort.</li>
470 <!-- ======================================================================= -->
471 <div class="doc_subsection">
472 <a name="sparc-be">Known problems with the Sparc back-end</a>
475 <div class="doc_text">
479 <li>The Sparc code generator <a
480 href="http://llvm.cs.uiuc.edu/PR15">does not currently
481 support the <tt>unwind</tt> instruction</a>, so code that throws a C++ exception
482 or calls the C <tt>longjmp</tt> function will abort.</li>
488 <!-- ======================================================================= -->
489 <div class="doc_subsection">
490 <a name="c-be">Known problems with the C back-end</a>
493 <div class="doc_text">
497 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
498 Analysis rules. As such, special options may be necessary to compile the code
499 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
500 problem probably cannot be fixed.</li>
502 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
503 cannot include special floating point numbers like Not-A-Number or
506 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
507 supported</a>. This should not affect LLVM produced by the C or C++
514 <!-- *********************************************************************** -->
515 <div class="doc_section">
516 <a name="additionalinfo">Additional Information</a>
518 <!-- *********************************************************************** -->
520 <div class="doc_text">
522 <p>A wide variety of additional information is available on the LLVM web page,
523 including mailing lists publications describing algorithms and components
524 implemented in LLVM. The web page also contains versions of the API
525 documentation which is up-to-date with the CVS version of the source code. You
526 can access versions of these documents specific to this release by going into
527 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
529 <p>If you have any questions or comments about LLVM, please feel free to contact
530 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
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