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6 <title>LLVM 1.3 Release Notes</title>
10 <div class="doc_title">LLVM 1.3 Release Notes</div>
13 <li><a href="#intro">Introduction</a></li>
14 <li><a href="#whatsnew">What's New?</a></li>
15 <li><a href="GettingStarted.html">Installation Instructions</a></li>
16 <li><a href="#portability">Portability and Supported Platforms</a></li>
17 <li><a href="#knownproblems">Known Problems</a>
19 <li><a href="#experimental">Experimental features included in this
21 <li><a href="#core">Known problems with the LLVM Core</a>
22 <li><a href="#c-fe">Known problems with the C Front-end</a>
23 <li><a href="#c++-fe">Known problems with the C++ Front-end</a>
24 <li><a href="#x86-be">Known problems with the X86 Back-end</a>
25 <li><a href="#sparc-be">Known problems with the Sparc Back-end</a>
26 <li><a href="#c-be">Known problems with the C back-end</a>
28 <li><a href="#additionalinfo">Additional Information</a></li>
31 <div class="doc_text">
32 <p><b>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM team</a></b><p>
35 <!-- *********************************************************************** -->
36 <div class="doc_section">
37 <a name="intro">Introduction</a>
39 <!-- *********************************************************************** -->
41 <div class="doc_text">
43 <p>This document contains the release notes for the LLVM compiler
44 infrastructure, release 1.3. Here we describe the status of LLVM, including any
45 known problems and bug fixes from the previous release. The most up-to-date
46 version of this document can be found on the <a
47 href="http://llvm.cs.uiuc.edu/releases/1.3/">LLVM 1.3 web site</a>. If you are
48 not reading this on the LLVM web pages, you should probably go there because
49 this document may be updated after the release.</p>
51 <p>For more information about LLVM, including information about potentially more
52 current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
53 web site</a>. If you have questions or comments, the <a
54 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
55 list</a> is a good place to send them.</p>
57 <p>Note that if you are reading this file from CVS, this document applies
58 to the <i>next</i> release, not the current one. To see the release notes for
59 the current or previous releases, see the <a
60 href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
64 <!-- *********************************************************************** -->
65 <div class="doc_section">
66 <a name="whatsnew">What's New?</a>
68 <!-- *********************************************************************** -->
70 <div class="doc_text">
73 This is the fourth public release of the LLVM compiler infrastructure.
77 At this time, LLVM is known to correctly compile and run all C & C++ SPEC
78 CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist benchmarks. It has
79 also been used to compile <b>many</b> other programs. LLVM now also works with
80 a broad variety of C++ programs, though it has still received less testing than
84 <!--=========================================================================-->
85 <div class="doc_subsubsection">
86 <a name="newfeatures">This release implements the following new features:</a>
90 <li>The LLVM <a href="LangRef.html#i_select"><tt>select</tt></a> instruction is
91 now fully implemented and supported by all targets, including
92 <a href="http://llvm.cs.uiuc.edu/PR322">interpreter support.</a></li>
93 <li>Bugpoint can now narrow down code-generation bugs to a loop nest, where
94 before it could only narrow them down to a function being miscompiled.</li>
98 <!--=========================================================================-->
99 <div class="doc_subsubsection">
100 In this release, the following missing features were implemented:
104 <li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
105 more than 256 elements</a></li>
106 <li><a href="http://llvm.cs.uiuc.edu/PR38">[bugpoint] External functions used in
107 non-instruction entities, such as global constant initializer</a></li>
108 <li><a href="http://llvm.cs.uiuc.edu/PR290">Bugpoint doesn't support
109 uses of external fns by immediate constant exprs</a></li>
113 <!--=========================================================================-->
114 <div class="doc_subsubsection">
115 <a name="qualityofimp">In this release, the following Quality of Implementation
116 issues were fixed:</a>
120 <li><a href="http://llvm.cs.uiuc.edu/PR305">LLVM tools will happily spew
121 bytecode onto your terminal</a></li>
124 <!--=========================================================================-->
125 <div class="doc_subsubsection">
126 In this release, the following build problems were fixed:
130 <li><a href="http://llvm.cs.uiuc.edu/PR301">Minor configure bugs with -disable/enable-povray and -disable-spec</a></li>
133 <!--=========================================================================-->
134 <div class="doc_subsubsection">
135 <a name="codequality">In this release, the following Code Quality issues were
140 <li><a href="http://llvm.cs.uiuc.edu/PR309">[vmcore] Code quality problem due to
141 long operand of getelementptr</a></li>
143 <li>The X86 backend now generates substantially better code for 64-bit integer
144 and floating point operations.</li>
146 <li>The -inline pass no longer inlines mutually recursive functions until it
147 hits the inlining threshold.</li>
149 <li>The -inline pass no longer misses obvious inlining opportunities just
150 because the callee eventually calls into an external function.</li>
152 <li>The -simplifycfg pass can now "if convert" simple statements into the new
153 <tt>select</tt> instruction.</li>
155 <li>The -loopsimplify pass can now break <a
156 href="http://llvm.cs.uiuc.edu/PR35">natural loops with multiple backedges</a>
157 into multiple nested loops. This enables a variety of subsequent
160 <li>The -adce pass can now eliminate calls to functions that do not not write to
163 <li>The link-time optimizer now runs the -prune-eh pass (to remove unused
164 exception handlers.</li>
169 <!--=========================================================================-->
170 <div class="doc_subsubsection">
171 <a name="bugfix">In this release, the following bugs in the previous release
175 <p>Bugs in the LLVM Core:</p>
178 <li><a href="http://llvm.cs.uiuc.edu/PR306">[loopsimplify] Loop simplify
179 incorrectly updates dominator information</a></li>
180 <li><a href="http://llvm.cs.uiuc.edu/PR310">[tailduplicate] DemoteRegToStack
181 breaks SSA form</a></li>
182 <li><a href="http://llvm.cs.uiuc.edu/PR313">[X86] JIT miscompiles unsigned short
183 to floating point cast</a></li>
188 <p>Bugs in the C/C++ front-end:</p>
191 <li><a href="http://llvm.cs.uiuc.edu/PR326">[llvmgcc] Crash on use of undeclared enum type</a></li></li>
196 <!-- *********************************************************************** -->
197 <div class="doc_section">
198 <a name="portability">Portability and Supported Platforms</a>
200 <!-- *********************************************************************** -->
202 <div class="doc_text">
204 <p>LLVM has been extensively tested on Intel and AMD machines running Red
205 Hat Linux and FreeBSD. It has also been tested on Sun UltraSPARC workstations
206 running Solaris 8. Additionally, LLVM works on Mac OS X 10.3 and above, but
207 only with the C backend or interpreter (no native backend for the PowerPC is
208 available yet). The core LLVM infrastructure uses "autoconf" for portability,
209 so hopefully we work on more platforms than that. However, it is likely that we
210 missed something and that minor porting is required to get LLVM to work on new
211 platforms. We welcome portability patches and error messages.</p>
215 <!--=========================================================================-->
216 <div class="doc_subsection">
217 In this release, the following portability problems were fixed:
221 <li><a href="http://llvm.cs.uiuc.edu/PR304">warnings compiling Stacker compiler on Mac OS X</a></li>
222 <li><a href="http://llvm.cs.uiuc.edu/PR308">getObjectType doesn't understand abbreviated names in headers</a></li>
225 <!-- *********************************************************************** -->
226 <div class="doc_section">
227 <a name="knownproblems">Known Problems</a>
229 <!-- *********************************************************************** -->
231 <div class="doc_text">
233 <p>This section contains all known problems with the LLVM system, listed by
234 component. As new problems are discovered, they will be added to these
235 sections. If you run into a problem, please check the <a
236 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
237 there isn't already one.</p>
241 <!-- ======================================================================= -->
242 <div class="doc_subsection">
243 <a name="experimental">Experimental features included with this release</a>
246 <div class="doc_text">
249 The following components of this LLVM release are either untested, known to be
250 broken or unreliable, or are in early development. These components should not
251 be relied on, and bugs should not be filed against them, but they may be useful
252 to some people. In particular, if you would like to work on one of these
253 components, please contact us on the llvmdev list.
257 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
258 -ipmodref, -sortstructs, -swapstructs, -cee</tt></li>
260 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
261 it should) and not thoroughly tested.</li>
262 <li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
263 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
268 <!-- ======================================================================= -->
269 <div class="doc_subsection">
270 <a name="core">Known problems with the LLVM Core</a>
273 <div class="doc_text">
277 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
280 <li>The JIT does not use mutexes to protect its internal data structures. As
281 such, execution of a threaded program could cause these data structures to be
284 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
286 <li>Linking in static archive files (.a files) is very slow (there is no symbol
287 table in the archive).</li>
289 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
290 objects/archives in the order specified on the command line.</a></li>
292 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
293 values live across a setjmp as volatile</a>. This missing feature only affects
294 targets whose setjmp/longjmp libraries do not save and restore the entire
299 <!-- ======================================================================= -->
300 <div class="doc_subsection">
301 <a name="c-fe">Known problems with the C front-end</a>
304 <!-- _______________________________________________________________________ -->
305 <div class="doc_subsubsection">Bugs</div>
307 <div class="doc_text">
309 <li>C99 Variable sized arrays do not release stack memory when they go out of
310 scope. Thus, the following program may run out of stack space:
312 for (i = 0; i != 1000000; ++i) {
319 Initialization of global union variables can only be done
320 <a href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest
324 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
325 external function is re-declared as static</a></li>
330 <!-- _______________________________________________________________________ -->
331 <div class="doc_subsubsection">
335 <div class="doc_text">
339 <li>Inline assembly is not yet supported.</li>
341 <li>"long double" is transformed by the front-end into "double". There is no
342 support for floating point data types of any size other than 32 and 64
345 <li>The following Unix system functionality has not been tested and may not
348 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
349 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
350 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
351 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
352 - These functions have not been tested.
355 <li>Although many GCC extensions are supported, some are not. In particular,
356 the following extensions are known to <b>not be</b> supported:
358 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
359 <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>
360 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
361 <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>
362 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
363 <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>
364 <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>
365 <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>
366 <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>
367 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
368 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
371 <p>The following GCC extensions are <b>partially</b> supported. An ignored
372 attribute means that the LLVM compiler ignores the presence of the attribute,
373 but the code should still work. An unsupported attribute is one which is
374 ignored by the LLVM compiler and will cause a different interpretation of
378 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
379 Arrays whose length is computed at run time.<br>
380 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
382 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
384 Declaring that functions have no side effects or that they can never
387 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
388 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
389 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
391 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
392 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
393 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
395 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
396 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
397 <tt>fastcall</tt>, all other target specific attributes</li>
399 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
400 Specifying attributes of variables.<br>
401 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
402 <tt>deprecated</tt>, <tt>transparent_union</tt>,
403 <tt>unused</tt>, <tt>weak</tt><br>
405 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
406 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
407 <tt>vector_size</tt>, <tt>dllimport</tt>,
408 <tt>dllexport</tt>, all target specific attributes.</li>
410 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
411 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
412 <tt>deprecated</tt>, <tt>may_alias</tt><br>
414 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
415 all target specific attributes.</li>
417 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
418 Other built-in functions.<br>
419 We support all builtins which have a C language equivalent (e.g.,
420 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
421 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
422 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
426 <p>The following extensions <b>are</b> known to be supported:</p>
429 <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>
430 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
431 <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>
432 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
433 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
434 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
435 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
436 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
437 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
438 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
439 <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>
440 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
441 <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>
442 <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>
443 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
444 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
445 or arrays as values.</li>
446 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
447 <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>
448 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
449 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
450 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
451 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
452 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
453 <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>
454 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
456 <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>
457 <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>
458 <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>
459 <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>
460 <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>
461 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
466 <p>If you run into GCC extensions which have not been included in any of these
467 lists, please let us know (also including whether or not they work).</p>
471 <!-- ======================================================================= -->
472 <div class="doc_subsection">
473 <a name="c++-fe">Known problems with the C++ front-end</a>
476 <div class="doc_text">
478 <p>For this release, the C++ front-end is considered to be fully functional but
479 has not been tested as thoroughly as the C front-end. It has been tested and
480 works for a number of non-trivial programs, but there may be lurking bugs.
481 Please report any bugs or problems.</p>
485 <!-- _______________________________________________________________________ -->
486 <div class="doc_subsubsection">Bugs</div>
488 <div class="doc_text">
491 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
496 <!-- _______________________________________________________________________ -->
497 <div class="doc_subsubsection">
501 <div class="doc_text">
505 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
506 parser is significantly more standards compliant (and picky) than prior GCC
507 versions. For more information, see the C++ section of the <a
508 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
510 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
511 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
512 function and in the <tt>setjmp</tt> receiver function may not be run.
513 Objects in intervening stack frames will be destroyed, however (which is
514 better than most compilers).</li>
516 <li>The LLVM C++ front-end follows the <a
517 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
518 This document, which is not Itanium specific, specifies a standard for name
519 mangling, class layout, v-table layout, RTTI formats, and other C++
520 representation issues. Because we use this API, code generated by the LLVM
521 compilers should be binary compatible with machine code generated by other
522 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
523 <i>However</i>, the exception handling mechanism used by LLVM is very
524 different from the model used in the Itanium ABI, so <b>exceptions will not
525 interact correctly</b>. </li>
531 <!-- ======================================================================= -->
532 <div class="doc_subsection">
533 <a name="x86-be">Known problems with the X86 back-end</a>
536 <div class="doc_text">
544 <!-- ======================================================================= -->
545 <div class="doc_subsection">
546 <a name="sparc-be">Known problems with the Sparc back-end</a>
549 <div class="doc_text">
552 <li>There are several programs in the LLVM testsuite that the Sparc code generator is known to miscompile.</li>
557 <!-- ======================================================================= -->
558 <div class="doc_subsection">
559 <a name="c-be">Known problems with the C back-end</a>
562 <div class="doc_text">
566 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
567 Analysis rules. As such, special options may be necessary to compile the code
568 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
569 problem probably cannot be fixed.</li>
571 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
572 cannot include special floating point numbers like Not-A-Number or
575 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
576 supported</a>. This should not affect LLVM produced by the C or C++
583 <!-- *********************************************************************** -->
584 <div class="doc_section">
585 <a name="additionalinfo">Additional Information</a>
587 <!-- *********************************************************************** -->
589 <div class="doc_text">
591 <p>A wide variety of additional information is available on the LLVM web page,
592 including mailing lists and publications describing algorithms and components
593 implemented in LLVM. The web page also contains versions of the API
594 documentation which is up-to-date with the CVS version of the source code. You
595 can access versions of these documents specific to this release by going into
596 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
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