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7 <title>LLVM 1.4 Release Notes</title>
11 <div class="doc_title">LLVM 1.4 Release Notes</div>
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#whatsnew">What's New?</a></li>
16 <li><a href="GettingStarted.html">Installation Instructions</a></li>
17 <li><a href="#portability">Portability and Supported Platforms</a></li>
18 <li><a href="#knownproblems">Known Problems</a>
20 <li><a href="#experimental">Experimental features included in this
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="#sparcv9-be">Known problems with the SparcV9 Back-end</a>
27 <li><a href="#ppc-be">Known problems with the PowerPC Back-end</a>
28 <li><a href="#c-be">Known problems with the C back-end</a>
30 <li><a href="#additionalinfo">Additional Information</a></li>
33 <div class="doc_author">
34 <p>Written by the <a href="http://llvm.cs.uiuc.edu">LLVM team</a><p>
37 <!-- *********************************************************************** -->
38 <div class="doc_section">
39 <a name="intro">Introduction</a>
41 <!-- *********************************************************************** -->
43 <div class="doc_text">
45 <p>This document contains the release notes for the LLVM compiler
46 infrastructure, release 1.4. Here we describe the status of LLVM, including any
47 known problems and bug fixes from the previous release. The most up-to-date
48 version of this document can be found on the <a
49 href="http://llvm.cs.uiuc.edu/releases/1.4/">LLVM 1.4 web site</a>. If you are
50 not reading this on the LLVM web pages, you should probably go there because
51 this document may be updated after the release.</p>
53 <p>For more information about LLVM, including information about potentially more
54 current releases, please check out the <a href="http://llvm.cs.uiuc.edu">main
55 web site</a>. If you have questions or comments, the <a
56 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
57 list</a> is a good place to send them.</p>
59 <p>Note that if you are reading this file from CVS, this document applies
60 to the <i>next</i> release, not the current one. To see the release notes for
61 the current or previous releases, see the <a
62 href="http://llvm.cs.uiuc.edu/releases/">releases page</a>.</p>
66 <!-- *********************************************************************** -->
67 <div class="doc_section">
68 <a name="whatsnew">What's New?</a>
70 <!-- *********************************************************************** -->
72 <div class="doc_text">
74 <p>This is the fifth public release of the LLVM compiler infrastructure.</p>
76 <p> At this time, LLVM is known to correctly compile and run all C & C++
77 SPEC CPU95 & 2000 benchmarks, the Olden benchmarks, and the Ptrdist
78 benchmarks, and <b>many</b> other C and C++ programs.</p>
82 <!--=========================================================================-->
83 <div class="doc_subsubsection">
84 <a name="newfeatures">This release implements the following new features:</a>
87 <div class="doc_text">
90 <li>The test/Programs hierarchy <a href="http://llvm.cs.uiuc.edu/PR257">has
91 been moved out of the main LLVM tree</a> into a separate CVS repo and
92 tarball. This shrinks the distribution size of LLVM itself dramatically.
94 <li>LLVM now optimizes global variables significantly more than it did
96 <li>LLVM now includes the new '<tt>undef</tt>' value and <a
97 href="LangRef.html#i_unreachable"><tt>unreachable</tt></a> instruction,
98 which give the optimizer more information about the behavior of the
100 <li>The LLVM makefiles have been improved to build LLVM much faster (2x) and
101 includes new targets (like dist-check, uninstall). One important change is
102 associated with <a href="http://llvm.cs.uiuc.edu/PR456>PR456">PR456</a>.
103 The libraries and tools will now be built into
104 <tt>$builddir/Debug/{bin,lib}</tt> instead of
105 <tt>$builddir/tools/Debug</tt> and <tt>$builddir/lib/Debug</tt>. Similarly
106 for <tt>Release</tt> and <tt>Profile</tt> builds.
108 <li>The LLVM source code is much more compatible with Microsoft Visual C++,
109 including the JIT and runtime-code generation, though the entire system
110 may not work with it.</li>
111 <li>llvmgcc and llvmg++ now emit source line number information when '-g' is
112 passed in. This information can be used with llvm-db or other tools and
119 <!--=========================================================================-->
120 <div class="doc_subsubsection">
121 In this release, the following missing features were implemented:
124 <div class="doc_text">
127 <li><a href="http://llvm.cs.uiuc.edu/PR419">JIT interface should support
128 arbitrary calls</a></li>
129 <li>The <tt>llvm-ar</tt> tool was previously incomplete and didn't properly
130 support other ar(1) implementations. This has been corrected. <tt>llvm-ar</tt>
131 now fully supports all archive editing functions, table of contents listing,
132 extraction, and printing. It can also read BSD4.4/MacOSX and SVR4 style
134 href="http://llvm.cs.uiuc.edu/docs/CommandGuide/html/llvm-ar.html">llvm-ar</a>
140 <!--=========================================================================-->
141 <div class="doc_subsubsection">
142 <a name="qualityofimp">In this release, the following Quality of Implementation
143 issues were fixed:</a>
146 <div class="doc_text">
149 <li><a href="http://llvm.cs.uiuc.edu/PR426">[llvmg++] Tons of warnings are spewed when
150 linking to libstdc++</a></li>
151 <li><a href="http://llvm.cs.uiuc.edu/PR352">include/{Support,Config} ->
152 include/llvm/{Support,Config}</a></li>
153 <li>The names of the libraries generated by compiling LLVM source have been
154 changed to ensure they do not conflict with other packages upon installation.
155 Each LLVM library is now prefixed with LLVM and uses mixed clase. For example,
156 the library <tt>libasmparser.a</tt> in 1.3 has become
157 <tt>libLLVMAsmParser.a</tt> in release 1.4.</li>
162 <!--=========================================================================-->
163 <div class="doc_subsubsection">
164 In this release, the following build problems were fixed:
167 <div class="doc_text">
173 <!--=========================================================================-->
174 <div class="doc_subsubsection">
175 <a name="codequality">This release includes the following Code Quality
179 <div class="doc_text">
181 <li><a href="http://llvm.cs.uiuc.edu/PR362">Ugly code generated for
182 std::min/std::max</a></li>
186 <!--=========================================================================-->
187 <div class="doc_subsubsection">
188 <a name="bugfix">In this release, the following bugs in the previous release
192 <div class="doc_text">
194 <p>Bugs fixed in the LLVM Core:</p>
197 <li><a href="http://llvm.cs.uiuc.edu/PR420">[licm] LICM invalidates alias analysis info
198 and uses broken information</a> (optimizer crash)</li>
199 <li><a href="http://llvm.cs.uiuc.edu/PR422">[asmwriter] Asmwriter is really slow for
200 functions with lots of values</a></li>
201 <li><a href="http://llvm.cs.uiuc.edu/PR423">[anders-aa] Andersen's AA is completely
202 broken in LLVM 1.3</a></li>
203 <li><a href="http://llvm.cs.uiuc.edu/PR430">[bcwriter] Empty compaction tables
205 <li><a href="http://llvm.cs.uiuc.edu/PR227">[X86] llc output for functions w/certain
206 names tickles GNU 'as' bugs</a></li>
209 <p>Bugs in the C/C++ front-end:</p>
212 <li><a href="http://llvm.cs.uiuc.edu/PR445">[llvmg++] not enough templates are instantiated</a></li>
213 <li><a href="http://llvm.cs.uiuc.edu/PR450">[llvmg++] Extern const globals cannot be
214 marked 'constant' if they have nontrivial ctors or dtors</a></li>
217 <p>Bugs fixed in the Sparc V9 back-end:</p>
220 <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
221 failure with certain indirect calls</a></li>
226 <!-- *********************************************************************** -->
227 <div class="doc_section">
228 <a name="portability">Portability and Supported Platforms</a>
230 <!-- *********************************************************************** -->
232 <div class="doc_text">
234 <p>LLVM is known to work in the following platforms:</p>
237 <li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
238 other unix-like systems).</li>
239 <li>Sun UltraSPARC workstations running Solaris 8.</li>
240 <li>Intel and AMD machines running on Win32 with the Cygwin libraries.</li>
241 <li>PowerPC-based Mac OS X boxes, running 10.2 and above. Note that no JIT
242 support is available yet, and LLC support is beta. The C backend can be used
243 to produce stable code for this platform.</li>
246 <p>The core LLVM infrastructure uses
247 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
248 to the machine and operating system on which it is built. However, minor
249 porting may be required to get LLVM to work on new platforms. We welcome your
250 portability patches and reports of successful builds or error messages.</p>
252 <p>Note that the LLVM build system does not currently support directories with
253 spaces on them when running on Win32/cygwin. We strongly recommend running
254 LLVM and the C frontend out of a top-level directory without spaces (e.g.,
255 <tt>/cygdrive/c/llvm</tt>). Also, make sure to install <b>all</b> of the
256 cygwin packages. By default, many important tools are not installed that
257 are needed by the LLVM build process or test suite (e.g., /bin/time). Finally,
258 please make sure that there are no directories with spaces in them in your
259 PATH environment variable.</p>
263 <!-- *********************************************************************** -->
264 <div class="doc_section">
265 <a name="knownproblems">Known Problems</a>
267 <!-- *********************************************************************** -->
269 <div class="doc_text">
271 <p>This section contains all known problems with the LLVM system, listed by
272 component. As new problems are discovered, they will be added to these
273 sections. If you run into a problem, please check the <a
274 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
275 there isn't already one.</p>
279 <!-- ======================================================================= -->
280 <div class="doc_subsection">
281 <a name="experimental">Experimental features included with this release</a>
284 <div class="doc_text">
286 <p>The following components of this LLVM release are either untested, known to
287 be broken or unreliable, or are in early development. These components should
288 not be relied on, and bugs should not be filed against them, but they may be
289 useful to some people. In particular, if you would like to work on one of these
290 components, please contact us on the llvmdev list.</p>
293 <li>The PowerPC backend is incomplete and is known to miscompile several SPEC
294 benchmarks. The file <tt>llvm/lib/Target/PowerPC/README.txt</tt> has
296 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
297 -ipmodref, -cee, -branch-combine, -instloops, -paths</tt></li>
298 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
299 it should) and not thoroughly tested.</li>
300 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
305 <!-- ======================================================================= -->
306 <div class="doc_subsection">
307 <a name="core">Known problems with the LLVM Core</a>
310 <div class="doc_text">
314 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
317 <li>The JIT does not use mutexes to protect its internal data structures. As
318 such, execution of a threaded program could cause these data structures to be
321 <li>Linking in static archive files (.a files) is slow (there is no symbol
322 table in the archive).</li>
324 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
325 objects/archives in the order specified on the command line.</a></li>
327 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
328 values live across a setjmp as volatile</a>. This missing feature only affects
329 targets whose setjmp/longjmp libraries do not save and restore the entire
334 <!-- ======================================================================= -->
335 <div class="doc_subsection">
336 <a name="c-fe">Known problems with the C front-end</a>
339 <!-- _______________________________________________________________________ -->
340 <div class="doc_subsubsection">Bugs</div>
342 <div class="doc_text">
344 <li>C99 Variable sized arrays do not release stack memory when they go out of
345 scope. Thus, the following program may run out of stack space:
347 for (i = 0; i != 1000000; ++i) {
353 <li>Initialization of global union variables can only be done <a
354 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
357 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
358 external function is re-declared as static</a></li>
363 <!-- _______________________________________________________________________ -->
364 <div class="doc_subsubsection">
368 <div class="doc_text">
372 <li>Inline assembly is not yet supported.</li>
374 <li>"long double" is transformed by the front-end into "double". There is no
375 support for floating point data types of any size other than 32 and 64
378 <li>The following Unix system functionality has not been tested and may not
381 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
382 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
383 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
384 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
385 - These functions have not been tested.
388 <li>Although many GCC extensions are supported, some are not. In particular,
389 the following extensions are known to <b>not be</b> supported:
391 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
392 <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>
393 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
394 <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>
395 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
396 <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>
397 <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>
398 <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>
399 <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>
400 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
401 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
404 <p>The following GCC extensions are <b>partially</b> supported. An ignored
405 attribute means that the LLVM compiler ignores the presence of the attribute,
406 but the code should still work. An unsupported attribute is one which is
407 ignored by the LLVM compiler and will cause a different interpretation of
411 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
412 Arrays whose length is computed at run time.<br>
413 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
415 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
417 Declaring that functions have no side effects or that they can never
420 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
421 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
422 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
424 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
425 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
426 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
428 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
429 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
430 <tt>fastcall</tt>, all other target specific attributes</li>
432 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
433 Specifying attributes of variables.<br>
434 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
435 <tt>deprecated</tt>, <tt>transparent_union</tt>,
436 <tt>unused</tt>, <tt>weak</tt><br>
438 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
439 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
440 <tt>vector_size</tt>, <tt>dllimport</tt>,
441 <tt>dllexport</tt>, all target specific attributes.</li>
443 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
444 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
445 <tt>deprecated</tt>, <tt>may_alias</tt><br>
447 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
448 all target specific attributes.</li>
450 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
451 Other built-in functions.<br>
452 We support all builtins which have a C language equivalent (e.g.,
453 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
454 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
455 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
456 (currently ignored). We also support builtins for ISO C99 floating
457 point comparison macros (e.g., <tt>__builtin_islessequal</tt>).</li>
460 <p>The following extensions <b>are</b> known to be supported:</p>
463 <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>
464 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
465 <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>
466 <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>
467 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
468 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
469 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
470 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
471 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
472 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
473 <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>
474 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
475 <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>
476 <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>
477 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
478 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
479 or arrays as values.</li>
480 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
481 <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>
482 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
483 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
484 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
485 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
486 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
487 <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>
488 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
490 <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>
491 <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>
492 <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>
493 <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>
494 <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>
495 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
500 <p>If you run into GCC extensions which have not been included in any of these
501 lists, please let us know (also including whether or not they work).</p>
505 <!-- ======================================================================= -->
506 <div class="doc_subsection">
507 <a name="c++-fe">Known problems with the C++ front-end</a>
510 <div class="doc_text">
512 <p>For this release, the C++ front-end is considered to be fully functional but
513 has not been tested as thoroughly as the C front-end. It has been tested and
514 works for a number of non-trivial programs, but there may be lurking bugs.
515 Please report any bugs or problems.</p>
519 <!-- _______________________________________________________________________ -->
520 <div class="doc_subsubsection">Bugs</div>
522 <div class="doc_text">
525 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
528 <li><b>IA-64 specific</b>: The C++ front-end does not use <a
529 href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
530 In particular, it just stores function pointers instead of function
531 descriptors in the vtable. This bug prevents mixing C++ code compiled with
532 LLVM with C++ objects compiled by other C++ compilers.</li>
538 <!-- _______________________________________________________________________ -->
539 <div class="doc_subsubsection">
543 <div class="doc_text">
547 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
548 parser is significantly more standards compliant (and picky) than prior GCC
549 versions. For more information, see the C++ section of the <a
550 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
552 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
553 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
554 function and in the <tt>setjmp</tt> receiver function may not be run.
555 Objects in intervening stack frames will be destroyed, however (which is
556 better than most compilers).</li>
558 <li>The LLVM C++ front-end follows the <a
559 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
560 This document, which is not Itanium specific, specifies a standard for name
561 mangling, class layout, v-table layout, RTTI formats, and other C++
562 representation issues. Because we use this API, code generated by the LLVM
563 compilers should be binary compatible with machine code generated by other
564 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
565 <i>However</i>, the exception handling mechanism used by LLVM is very
566 different from the model used in the Itanium ABI, so <b>exceptions will not
567 interact correctly</b>. </li>
573 <!-- ======================================================================= -->
574 <div class="doc_subsection">
575 <a name="x86-be">Known problems with the X86 back-end</a>
578 <div class="doc_text">
586 <!-- ======================================================================= -->
587 <div class="doc_subsection">
588 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
591 <div class="doc_text">
594 <li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
595 several programs in the LLVM test suite</a></li>
600 <!-- ======================================================================= -->
601 <div class="doc_subsection">
602 <a name="ppc-be">Known problems with the PowerPC back-end</a>
605 <div class="doc_text">
613 <!-- ======================================================================= -->
614 <div class="doc_subsection">
615 <a name="c-be">Known problems with the C back-end</a>
618 <div class="doc_text">
622 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
623 Analysis rules. As such, special options may be necessary to compile the code
624 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
625 problem probably cannot be fixed.</li>
627 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
628 cannot include special floating point numbers like Not-A-Number or
631 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
632 supported</a>. This should not affect LLVM produced by the C or C++
639 <!-- *********************************************************************** -->
640 <div class="doc_section">
641 <a name="additionalinfo">Additional Information</a>
643 <!-- *********************************************************************** -->
645 <div class="doc_text">
647 <p>A wide variety of additional information is available on the LLVM web page,
648 including mailing lists and publications describing algorithms and components
649 implemented in LLVM. The web page also contains versions of the API
650 documentation which is up-to-date with the CVS version of the source code. You
651 can access versions of these documents specific to this release by going into
652 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
654 <p>If you have any questions or comments about LLVM, please feel free to contact
655 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
660 <!-- *********************************************************************** -->
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