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6 <title>LLVM 1.4 Release Notes</title>
10 <div class="doc_title">LLVM 1.4 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="#sparcv9-be">Known problems with the SparcV9 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_author">
32 <p>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM team</a><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 1.4. 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/1.4/">LLVM 1.4 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">
72 <p>This is the fifth public release of the LLVM compiler infrastructure.</p>
74 <p> At this time, LLVM is known to correctly compile and run all C & C++
75 SPEC CPU95 & 2000 benchmarks, the Olden benchmarks, and the Ptrdist
76 benchmarks, and <b>many</b> other C and C++ programs.</p>
80 <!--=========================================================================-->
81 <div class="doc_subsubsection">
82 <a name="newfeatures">This release implements the following new features:</a>
85 <div class="doc_text">
88 <li>The test/Programs hierarchy <a href="http://llvm.cs.uiuc.edu/PR257">has
89 been moved out of the main LLVM tree</a> into a separate CVS repo and
91 <li>LLVM now optimizes global variables significantly more than it did
93 <li>LLVM now includes the new '<tt>undef</tt>' value and <a
94 href="LangRef.html#i_unreachable"><tt>unreachable</tt></a> instruction,
95 which give the optimizer more information about the behavior of the
102 <!--=========================================================================-->
103 <div class="doc_subsubsection">
104 In this release, the following missing features were implemented:
107 <div class="doc_text">
110 <li><a href="http://llvm.cs.uiuc.edu/PR419">JIT interface should support
111 arbitrary calls</a></li>
116 <!--=========================================================================-->
117 <div class="doc_subsubsection">
118 <a name="qualityofimp">In this release, the following Quality of Implementation
119 issues were fixed:</a>
122 <div class="doc_text">
125 <li><a href="http://llvm.cs.uiuc.edu/PR426">[llvmg++] Tons of warnings are spewed when
126 linking to libstdc++</a></li>
127 <li><a href="http://llvm.cs.uiuc.edu/PR352">include/{Support,Config} ->
128 include/llvm/{Support,Config}</a></li>
133 <!--=========================================================================-->
134 <div class="doc_subsubsection">
135 In this release, the following build problems were fixed:
138 <div class="doc_text">
144 <!--=========================================================================-->
145 <div class="doc_subsubsection">
146 <a name="codequality">This release includes the following Code Quality
150 <div class="doc_text">
152 <li><a href="http://llvm.cs.uiuc.edu/PR362">Ugly code generated for
153 std::min/std::max</a></li>
157 <!--=========================================================================-->
158 <div class="doc_subsubsection">
159 <a name="bugfix">In this release, the following bugs in the previous release
163 <div class="doc_text">
165 <p>Bugs fixed in the LLVM Core:</p>
168 <li><a href="http://llvm.cs.uiuc.edu/PR420">[licm] LICM invalidates alias analysis info
169 and uses broken information</a> (optimizer crash)</li>
170 <li><a href="http://llvm.cs.uiuc.edu/PR422">[asmwriter] Asmwriter is really slow for
171 functions with lots of values</a></li>
172 <li><a href="http://llvm.cs.uiuc.edu/PR423">[anders-aa] Andersen's AA is completely
173 broken in LLVM 1.3</a></li>
174 <li><a href="http://llvm.cs.uiuc.edu/PR430">[bcwriter] Empty compaction tables
176 <li><a href="http://llvm.cs.uiuc.edu/PR227">[X86] llc output for functions w/certain
177 names tickles GNU 'as' bugs</a></li>
180 <p>Bugs in the C/C++ front-end:</p>
183 <li><a href="http://llvm.cs.uiuc.edu/PR445">[llvmg++] not enough templates are instantiated</a></li>
184 <li><a href="http://llvm.cs.uiuc.edu/PR450">[llvmg++] Extern const globals cannot be
185 marked 'constant' if they have nontrivial ctors or dtors</a></li>
188 <p>Bugs fixed in the Sparc V9 back-end:</p>
191 <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
192 failure with certain indirect calls</a></li>
197 <!-- *********************************************************************** -->
198 <div class="doc_section">
199 <a name="portability">Portability and Supported Platforms</a>
201 <!-- *********************************************************************** -->
203 <div class="doc_text">
205 <p>LLVM is known to work in the following platforms:</p>
208 <li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
209 other unix-like systems).</li>
210 <li>Sun UltraSPARC workstations running Solaris 8.</li>
211 <li>Intel and AMD machines running on Win32 with the Cygwin libraries.</li>
212 <li>PowerPC-based Mac OS X boxes, running 10.2 and above. Note that no JIT
213 support is available yet, and LLC support is beta. The C backend can be used
214 to produce stable code for this platform.</li>
217 <p>The core LLVM infrastructure uses
218 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
219 to the machine and operating system on which it is built. However, minor
220 porting may be required to get LLVM to work on new platforms. We welcome your
221 portability patches and reports of successful builds or error messages.</p>
223 <p>Note that the LLVM build system does not currently support directories with
224 spaces on them when running on Win32/cygwin. We strongly recommend running
225 LLVM and the C frontend out of a top-level directory without spaces (e.g.,
226 <tt>/cygdrive/c/llvm</tt>). Also, make sure to install <b>all</b> of the
227 cygwin packages. By default, many important tools are not installed that
228 are needed by the LLVM build process or test suite (e.g., /bin/time). Finally,
229 please make sure that there are no directories with spaces in them in your
230 PATH environment variable.</p>
234 <!-- *********************************************************************** -->
235 <div class="doc_section">
236 <a name="knownproblems">Known Problems</a>
238 <!-- *********************************************************************** -->
240 <div class="doc_text">
242 <p>This section contains all known problems with the LLVM system, listed by
243 component. As new problems are discovered, they will be added to these
244 sections. If you run into a problem, please check the <a
245 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
246 there isn't already one.</p>
250 <!-- ======================================================================= -->
251 <div class="doc_subsection">
252 <a name="experimental">Experimental features included with this release</a>
255 <div class="doc_text">
257 <p>The following components of this LLVM release are either untested, known to
258 be broken or unreliable, or are in early development. These components should
259 not be relied on, and bugs should not be filed against them, but they may be
260 useful to some people. In particular, if you would like to work on one of these
261 components, please contact us on the llvmdev list.</p>
264 <li>The PowerPC backend is incomplete and is known to miscompile several SPEC
265 benchmarks. The file <tt>llvm/lib/Target/PowerPC/README.txt</tt> has
267 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
268 -ipmodref, -cee, -branch-combine, -instloops, -paths</tt></li>
269 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
270 it should) and not thoroughly tested.</li>
271 <li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
272 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
277 <!-- ======================================================================= -->
278 <div class="doc_subsection">
279 <a name="core">Known problems with the LLVM Core</a>
282 <div class="doc_text">
286 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
289 <li>The JIT does not use mutexes to protect its internal data structures. As
290 such, execution of a threaded program could cause these data structures to be
293 <li>Linking in static archive files (.a files) is slow (there is no symbol
294 table in the archive).</li>
296 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
297 objects/archives in the order specified on the command line.</a></li>
299 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
300 values live across a setjmp as volatile</a>. This missing feature only affects
301 targets whose setjmp/longjmp libraries do not save and restore the entire
306 <!-- ======================================================================= -->
307 <div class="doc_subsection">
308 <a name="c-fe">Known problems with the C front-end</a>
311 <!-- _______________________________________________________________________ -->
312 <div class="doc_subsubsection">Bugs</div>
314 <div class="doc_text">
316 <li>C99 Variable sized arrays do not release stack memory when they go out of
317 scope. Thus, the following program may run out of stack space:
319 for (i = 0; i != 1000000; ++i) {
325 <li>Initialization of global union variables can only be done <a
326 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
329 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
330 external function is re-declared as static</a></li>
335 <!-- _______________________________________________________________________ -->
336 <div class="doc_subsubsection">
340 <div class="doc_text">
344 <li>Inline assembly is not yet supported.</li>
346 <li>"long double" is transformed by the front-end into "double". There is no
347 support for floating point data types of any size other than 32 and 64
350 <li>The following Unix system functionality has not been tested and may not
353 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
354 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
355 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
356 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
357 - These functions have not been tested.
360 <li>Although many GCC extensions are supported, some are not. In particular,
361 the following extensions are known to <b>not be</b> supported:
363 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
364 <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>
365 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
366 <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>
367 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
368 <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>
369 <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>
370 <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>
371 <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>
372 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
373 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
376 <p>The following GCC extensions are <b>partially</b> supported. An ignored
377 attribute means that the LLVM compiler ignores the presence of the attribute,
378 but the code should still work. An unsupported attribute is one which is
379 ignored by the LLVM compiler and will cause a different interpretation of
383 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
384 Arrays whose length is computed at run time.<br>
385 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
387 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
389 Declaring that functions have no side effects or that they can never
392 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
393 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
394 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
396 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
397 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
398 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
400 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
401 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
402 <tt>fastcall</tt>, all other target specific attributes</li>
404 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
405 Specifying attributes of variables.<br>
406 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
407 <tt>deprecated</tt>, <tt>transparent_union</tt>,
408 <tt>unused</tt>, <tt>weak</tt><br>
410 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
411 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
412 <tt>vector_size</tt>, <tt>dllimport</tt>,
413 <tt>dllexport</tt>, all target specific attributes.</li>
415 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
416 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
417 <tt>deprecated</tt>, <tt>may_alias</tt><br>
419 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
420 all target specific attributes.</li>
422 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
423 Other built-in functions.<br>
424 We support all builtins which have a C language equivalent (e.g.,
425 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
426 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
427 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
428 (currently ignored). We also support builtins for ISO C99 floating
429 point comparison macros (e.g., <tt>__builtin_islessequal</tt>).</li>
432 <p>The following extensions <b>are</b> known to be supported:</p>
435 <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>
436 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
437 <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>
438 <li><a href="http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
439 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
440 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
441 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
442 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
443 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
444 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
445 <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>
446 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
447 <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>
448 <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>
449 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
450 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
451 or arrays as values.</li>
452 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
453 <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>
454 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
456 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
458 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
459 <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>
460 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
461 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
462 <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>
463 <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>
464 <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>
465 <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>
466 <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>
467 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
472 <p>If you run into GCC extensions which have not been included in any of these
473 lists, please let us know (also including whether or not they work).</p>
477 <!-- ======================================================================= -->
478 <div class="doc_subsection">
479 <a name="c++-fe">Known problems with the C++ front-end</a>
482 <div class="doc_text">
484 <p>For this release, the C++ front-end is considered to be fully functional but
485 has not been tested as thoroughly as the C front-end. It has been tested and
486 works for a number of non-trivial programs, but there may be lurking bugs.
487 Please report any bugs or problems.</p>
491 <!-- _______________________________________________________________________ -->
492 <div class="doc_subsubsection">Bugs</div>
494 <div class="doc_text">
497 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
500 <li><b>IA-64 specific</b>: The C++ front-end does not use <a
501 href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
502 In particular, it just stores function pointers instead of function
503 descriptors in the vtable. This bug prevents mixing C++ code compiled with
504 LLVM with C++ objects compiled by other C++ compilers.</li>
510 <!-- _______________________________________________________________________ -->
511 <div class="doc_subsubsection">
515 <div class="doc_text">
519 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
520 parser is significantly more standards compliant (and picky) than prior GCC
521 versions. For more information, see the C++ section of the <a
522 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
524 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
525 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
526 function and in the <tt>setjmp</tt> receiver function may not be run.
527 Objects in intervening stack frames will be destroyed, however (which is
528 better than most compilers).</li>
530 <li>The LLVM C++ front-end follows the <a
531 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
532 This document, which is not Itanium specific, specifies a standard for name
533 mangling, class layout, v-table layout, RTTI formats, and other C++
534 representation issues. Because we use this API, code generated by the LLVM
535 compilers should be binary compatible with machine code generated by other
536 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
537 <i>However</i>, the exception handling mechanism used by LLVM is very
538 different from the model used in the Itanium ABI, so <b>exceptions will not
539 interact correctly</b>. </li>
545 <!-- ======================================================================= -->
546 <div class="doc_subsection">
547 <a name="x86-be">Known problems with the X86 back-end</a>
550 <div class="doc_text">
558 <!-- ======================================================================= -->
559 <div class="doc_subsection">
560 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
563 <div class="doc_text">
566 <li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
567 several programs in the LLVM test suite</a></li>
572 <!-- ======================================================================= -->
573 <div class="doc_subsection">
574 <a name="c-be">Known problems with the C back-end</a>
577 <div class="doc_text">
581 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
582 Analysis rules. As such, special options may be necessary to compile the code
583 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
584 problem probably cannot be fixed.</li>
586 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
587 cannot include special floating point numbers like Not-A-Number or
590 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
591 supported</a>. This should not affect LLVM produced by the C or C++
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600 <a name="additionalinfo">Additional Information</a>
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606 <p>A wide variety of additional information is available on the LLVM web page,
607 including mailing lists and publications describing algorithms and components
608 implemented in LLVM. The web page also contains versions of the API
609 documentation which is up-to-date with the CVS version of the source code. You
610 can access versions of these documents specific to this release by going into
611 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
613 <p>If you have any questions or comments about LLVM, please feel free to contact
614 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
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