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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">
72 <p>This is the fourth public release of the LLVM compiler infrastructure. This
73 release primarily improves the <a href="#codequality">performance of the
74 code</a> produced by all aspects of the LLVM compiler and adds some <a
75 href="#newfeatures">new features</a>, though it does <a href="#bugfix">fix a few
78 <p> At this time, LLVM is known to correctly compile and run all C & C++
79 SPEC CPU2000 benchmarks, the Olden benchmarks, and the Ptrdist benchmarks. It
80 has also been used to compile <b>many</b> other programs. LLVM now also works
81 with a broad variety of C++ programs, though it has still received less testing
82 than the C front-end.</p>
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 transformations, native code
92 generators, and the interpreter.</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>
95 <li><a href="http://llvm.cs.uiuc.edu/PR40">Bugpoint can now debug arbitrary
96 modes of llc</a> and lli, by passing them command line flags (e.g.,
97 <tt>-regalloc=linearscan</tt>, <tt>-enable-correct-eh-support</tt>, etc.) </li>
98 <li>The Control Flow Graph in the native code generators is no longer
99 constrained to be the same as the CFG for the LLVM input code.</li>
100 <li>The LLVM induction variable analysis routines have been rewritten.</li>
101 <li>LLVM now has new loop unrolling and loop unswitching passes.</li>
102 <li>The induction variable substitution pass performs linear function test
103 replacement and exit value replacement optimizations.</li>
107 <!--=========================================================================-->
108 <div class="doc_subsubsection">
109 In this release, the following missing features were implemented:
113 <li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
114 more than 256 elements</a></li>
115 <li><a href="http://llvm.cs.uiuc.edu/PR38">[bugpoint] External functions used in
116 non-instruction entities, such as global constant initializer</a></li>
117 <li><a href="http://llvm.cs.uiuc.edu/PR178">Stacker does not handle targets
118 with 64-bit pointers.</a></li>
119 <li><a href="http://llvm.cs.uiuc.edu/PR290">Bugpoint doesn't support
120 uses of external fns by immediate constant exprs</a></li>
124 <!--=========================================================================-->
125 <div class="doc_subsubsection">
126 <a name="qualityofimp">In this release, the following Quality of Implementation
127 issues were fixed:</a>
131 <li><a href="http://llvm.cs.uiuc.edu/PR305">LLVM tools will happily spew
132 bytecode onto your terminal</a></li>
133 <li><a href="http://llvm.cs.uiuc.edu/PR329">[llvmgcc] type names are not emitted
134 for structure typedefs</a></li>
137 <!--=========================================================================-->
138 <div class="doc_subsubsection">
139 In this release, the following build problems were fixed:
143 <li><a href="http://llvm.cs.uiuc.edu/PR301">Minor configure bugs with
144 -disable/enable-povray and -disable-spec</a></li>
145 <li><a href="http://llvm.cs.uiuc.edu/PR289">shell scripts output by gccld don't
146 work if you change PATH</a></li>
149 <!--=========================================================================-->
150 <div class="doc_subsubsection">
151 <a name="codequality">This release includes the following Code Quality
156 <li>Fixed: <a href="http://llvm.cs.uiuc.edu/PR309">[vmcore] Code quality problem
157 due to long operand of getelementptr</a></li>
159 <li>The X86 backend now generates substantially better code for 64-bit integer
160 and floating point operations.</li>
162 <li>The -inline pass no longer inlines mutually recursive functions until it
163 hits the inlining threshold.</li>
165 <li>The -inline pass no longer misses obvious inlining opportunities just
166 because the callee eventually calls into an external function.</li>
168 <li>The -simplifycfg pass can now "if convert" simple statements into the new
169 <tt>select</tt> instruction.</li>
171 <li>The -loopsimplify pass can now break <a
172 href="http://llvm.cs.uiuc.edu/PR35">natural loops with multiple backedges</a>
173 into multiple nested loops. This enables a variety of subsequent
176 <li>The -adce pass can now eliminate calls to functions that do not not write to
179 <li>The link-time optimizer now runs the -prune-eh pass (to remove unused
180 exception handlers).</li>
182 <li>The -simplifycfg pass can now eliminate simple correlated branches (such as
183 "<tt>if (A < B && A < B)</tt>", and can turn short-circuiting
184 operators into the strict versions when useful (such as "<tt>if (A < B || A
185 > C)</tt>" into "<tt>if (A < B | A > C)</tt>"</li>
187 <li>LLVM now has infrastructure for (simple and sparse conditional) constant
188 propagation of function calls. It currently supports a few math library
189 functions like sqrt/sin/cos/etc.</li>
193 <!--=========================================================================-->
194 <div class="doc_subsubsection">
195 <a name="bugfix">In this release, the following bugs in the previous release
199 <p>Bugs in the LLVM Core:</p>
202 <li><a href="http://llvm.cs.uiuc.edu/PR330">[vmcore] Linker causes erroneous
204 <li><a href="http://llvm.cs.uiuc.edu/PR306">[loopsimplify] Loop simplify
205 incorrectly updates dominator information</a></li>
206 <li><a href="http://llvm.cs.uiuc.edu/PR310">[tailduplicate] DemoteRegToStack
207 breaks SSA form</a></li>
208 <li><a href="http://llvm.cs.uiuc.edu/PR313">[X86] JIT miscompiles unsigned short
209 to floating point cast</a></li>
210 <li><a href="http://llvm.cs.uiuc.edu/PR332">[adce] Crash handling unreachable
211 code that unwinds</a></li>
212 <li><a href="http://llvm.cs.uiuc.edu/PR333">[sparc] LLC can't emit 2 functions
213 of the same name, both having constant pools</a></li>
214 <li><a href="http://llvm.cs.uiuc.edu/PR337">[livevar] Live variables missed
215 physical register use of aliased definition</a></li>
218 <p>Bugs in the C/C++ front-end:</p>
221 <li><a href="http://llvm.cs.uiuc.edu/PR326">[llvmgcc] Crash on use of undeclared
223 <li><a href="http://llvm.cs.uiuc.edu/PR298">[llvmgcc] Variable length array
224 indexing miscompiled</a></li>
229 <!-- *********************************************************************** -->
230 <div class="doc_section">
231 <a name="portability">Portability and Supported Platforms</a>
233 <!-- *********************************************************************** -->
235 <div class="doc_text">
237 <p>LLVM has been extensively tested on Intel and AMD machines running Red Hat
238 Linux. It has also been tested under FreeBSD, and on Sun UltraSPARC
239 workstations running Solaris 8. Additionally, LLVM works on Mac OS X 10.3 and
240 above, but only with the C backend and interpreter; no native machine-code
241 generator for the PowerPC is available yet.</p>
243 <p>The core LLVM infrastructure uses
244 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
245 to the machine and operating system on which it is built. However, minor
246 porting may be required to get LLVM to work on new platforms. We welcome your
247 portability patches and reports of successful builds or error messages.</p>
251 <!--=========================================================================-->
252 <div class="doc_subsection">
253 In this release, the following portability problems were fixed:
257 <li><a href="http://llvm.cs.uiuc.edu/PR304">warnings compiling Stacker compiler
259 <li><a href="http://llvm.cs.uiuc.edu/PR308">Archive file reader doesn't
260 understand abbreviated names in headers</a></li>
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 following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
294 -ipmodref, -sortstructs, -swapstructs, -cee</tt></li>
296 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
297 it should) and not thoroughly tested.</li>
298 <li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
299 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
304 <!-- ======================================================================= -->
305 <div class="doc_subsection">
306 <a name="core">Known problems with the LLVM Core</a>
309 <div class="doc_text">
313 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
316 <li>The JIT does not use mutexes to protect its internal data structures. As
317 such, execution of a threaded program could cause these data structures to be
320 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
322 <li>Linking in static archive files (.a files) is very slow (there is no symbol
323 table in the archive).</li>
325 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
326 objects/archives in the order specified on the command line.</a></li>
328 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
329 values live across a setjmp as volatile</a>. This missing feature only affects
330 targets whose setjmp/longjmp libraries do not save and restore the entire
335 <!-- ======================================================================= -->
336 <div class="doc_subsection">
337 <a name="c-fe">Known problems with the C front-end</a>
340 <!-- _______________________________________________________________________ -->
341 <div class="doc_subsubsection">Bugs</div>
343 <div class="doc_text">
345 <li>C99 Variable sized arrays do not release stack memory when they go out of
346 scope. Thus, the following program may run out of stack space:
348 for (i = 0; i != 1000000; ++i) {
354 <li>Initialization of global union variables can only be done <a
355 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
358 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
359 external function is re-declared as static</a></li>
364 <!-- _______________________________________________________________________ -->
365 <div class="doc_subsubsection">
369 <div class="doc_text">
373 <li>Inline assembly is not yet supported.</li>
375 <li>"long double" is transformed by the front-end into "double". There is no
376 support for floating point data types of any size other than 32 and 64
379 <li>The following Unix system functionality has not been tested and may not
382 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
383 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
384 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
385 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
386 - These functions have not been tested.
389 <li>Although many GCC extensions are supported, some are not. In particular,
390 the following extensions are known to <b>not be</b> supported:
392 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
393 <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>
394 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
395 <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>
396 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
397 <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>
398 <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>
399 <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>
400 <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>
401 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
402 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
405 <p>The following GCC extensions are <b>partially</b> supported. An ignored
406 attribute means that the LLVM compiler ignores the presence of the attribute,
407 but the code should still work. An unsupported attribute is one which is
408 ignored by the LLVM compiler and will cause a different interpretation of
412 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
413 Arrays whose length is computed at run time.<br>
414 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
416 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
418 Declaring that functions have no side effects or that they can never
421 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
422 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
423 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
425 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
426 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
427 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
429 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
430 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
431 <tt>fastcall</tt>, all other target specific attributes</li>
433 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
434 Specifying attributes of variables.<br>
435 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
436 <tt>deprecated</tt>, <tt>transparent_union</tt>,
437 <tt>unused</tt>, <tt>weak</tt><br>
439 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
440 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
441 <tt>vector_size</tt>, <tt>dllimport</tt>,
442 <tt>dllexport</tt>, all target specific attributes.</li>
444 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
445 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
446 <tt>deprecated</tt>, <tt>may_alias</tt><br>
448 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
449 all target specific attributes.</li>
451 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
452 Other built-in functions.<br>
453 We support all builtins which have a C language equivalent (e.g.,
454 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
455 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
456 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</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/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
530 <!-- _______________________________________________________________________ -->
531 <div class="doc_subsubsection">
535 <div class="doc_text">
539 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
540 parser is significantly more standards compliant (and picky) than prior GCC
541 versions. For more information, see the C++ section of the <a
542 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
544 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
545 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
546 function and in the <tt>setjmp</tt> receiver function may not be run.
547 Objects in intervening stack frames will be destroyed, however (which is
548 better than most compilers).</li>
550 <li>The LLVM C++ front-end follows the <a
551 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
552 This document, which is not Itanium specific, specifies a standard for name
553 mangling, class layout, v-table layout, RTTI formats, and other C++
554 representation issues. Because we use this API, code generated by the LLVM
555 compilers should be binary compatible with machine code generated by other
556 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
557 <i>However</i>, the exception handling mechanism used by LLVM is very
558 different from the model used in the Itanium ABI, so <b>exceptions will not
559 interact correctly</b>. </li>
565 <!-- ======================================================================= -->
566 <div class="doc_subsection">
567 <a name="x86-be">Known problems with the X86 back-end</a>
570 <div class="doc_text">
578 <!-- ======================================================================= -->
579 <div class="doc_subsection">
580 <a name="sparc-be">Known problems with the Sparc back-end</a>
583 <div class="doc_text">
586 <li>There are several programs in the LLVM testsuite that the Sparc code generator is known to miscompile.</li>
591 <!-- ======================================================================= -->
592 <div class="doc_subsection">
593 <a name="c-be">Known problems with the C back-end</a>
596 <div class="doc_text">
600 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
601 Analysis rules. As such, special options may be necessary to compile the code
602 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
603 problem probably cannot be fixed.</li>
605 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
606 cannot include special floating point numbers like Not-A-Number or
609 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
610 supported</a>. This should not affect LLVM produced by the C or C++
617 <!-- *********************************************************************** -->
618 <div class="doc_section">
619 <a name="additionalinfo">Additional Information</a>
621 <!-- *********************************************************************** -->
623 <div class="doc_text">
625 <p>A wide variety of additional information is available on the LLVM web page,
626 including mailing lists and publications describing algorithms and components
627 implemented in LLVM. The web page also contains versions of the API
628 documentation which is up-to-date with the CVS version of the source code. You
629 can access versions of these documents specific to this release by going into
630 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
632 <p>If you have any questions or comments about LLVM, please feel free to contact
633 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
638 <!-- *********************************************************************** -->
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