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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_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 1.3. 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>
86 <!--=========================================================================-->
87 <div class="doc_subsubsection">
88 <a name="newfeatures">This release implements the following new features:</a>
91 <div class="doc_text">
94 <li>The LLVM <a href="LangRef.html#i_select"><tt>select</tt></a> instruction is
95 now fully implemented and supported by all transformations, native code
96 generators, and the interpreter.</li>
97 <li>Bugpoint can now narrow down code-generation bugs to a loop nest, where
98 before it could only narrow them down to a function being miscompiled.</li>
99 <li><a href="http://llvm.cs.uiuc.edu/PR40">Bugpoint can now debug arbitrary
100 modes of llc</a> and lli, by passing them command line flags (e.g.,
101 <tt>-regalloc=linearscan</tt>, <tt>-enable-correct-eh-support</tt>, etc.) </li>
102 <li>The Control Flow Graph in the native code generators is no longer
103 constrained to be the same as the CFG for the LLVM input code.</li>
104 <li>The LLVM induction variable analysis routines have been rewritten.</li>
105 <li>LLVM now has new loop unrolling and loop unswitching passes.</li>
106 <li>The induction variable substitution pass performs linear function test
107 replacement and exit value replacement optimizations.</li>
108 <li>The <a href="BytecodeFormat.html">LLVM Bytecode file format</a> is now
110 <li>LLVM now has first-class support for <a href="GarbageCollection.html">Accurate
111 Garbage Collection</a>, enabling the use of aggressive copying and generational
113 <li>LLVM now includes an implementation of Andersen's interprocedural alias
114 analysis algorithm.</li>
115 <li>Bugpoint can <a href="http://llvm.cs.uiuc.edu/PR327">extract individual
116 basic blocks</a> to track down reduce miscompilation testcases.</li>
117 <li>LLVM and the C front-end now work under Win32 using the cygnus libraries.
118 This includes the JIT compiler.</li>
124 <!--=========================================================================-->
125 <div class="doc_subsubsection">
126 In this release, the following missing features were implemented:
129 <div class="doc_text">
132 <li><a href="http://llvm.cs.uiuc.edu/PR82">LLVM cannot handle structures with
133 more than 256 elements</a></li>
134 <li><a href="http://llvm.cs.uiuc.edu/PR38">[bugpoint] External functions used in
135 non-instruction entities, such as global constant initializer</a></li>
136 <li><a href="http://llvm.cs.uiuc.edu/PR178">Stacker does not handle targets
137 with 64-bit pointers.</a></li>
138 <li><a href="http://llvm.cs.uiuc.edu/PR290">Bugpoint doesn't support
139 uses of external fns by immediate constant exprs</a></li>
144 <!--=========================================================================-->
145 <div class="doc_subsubsection">
146 <a name="qualityofimp">In this release, the following Quality of Implementation
147 issues were fixed:</a>
150 <div class="doc_text">
153 <li><a href="http://llvm.cs.uiuc.edu/PR305">LLVM tools will happily spew
154 bytecode onto your terminal</a></li>
155 <li><a href="http://llvm.cs.uiuc.edu/PR329">[llvmgcc] type names are not emitted
156 for structure typedefs</a></li>
157 <li>All documentation is now conformant to the HTML 4.01 (Strict) level.</li>
162 <!--=========================================================================-->
163 <div class="doc_subsubsection">
164 In this release, the following build problems were fixed:
167 <div class="doc_text">
169 <li><a href="http://llvm.cs.uiuc.edu/PR301">Minor configure bugs with
170 -disable/enable-povray and -disable-spec</a></li>
171 <li><a href="http://llvm.cs.uiuc.edu/PR289">shell scripts output by gccld don't
172 work if you change PATH</a></li>
176 <!--=========================================================================-->
177 <div class="doc_subsubsection">
178 <a name="codequality">This release includes the following Code Quality
182 <div class="doc_text">
184 <li>Fixed: <a href="http://llvm.cs.uiuc.edu/PR309">[vmcore] Code quality problem
185 due to long operand of getelementptr</a></li>
187 <li>The X86 backend now generates substantially better code for 64-bit integer
188 and floating point operations.</li>
190 <li>The -inline pass no longer inlines mutually recursive functions until it
191 hits the inlining threshold.</li>
193 <li>The -inline pass no longer misses obvious inlining opportunities just
194 because the callee eventually calls into an external function.</li>
196 <li>The -simplifycfg pass can now "if convert" simple statements into the new
197 <tt>select</tt> instruction.</li>
199 <li>The -loopsimplify pass can now break <a
200 href="http://llvm.cs.uiuc.edu/PR35">natural loops with multiple backedges</a>
201 into multiple nested loops. This enables a variety of subsequent
204 <li>The -adce pass can now eliminate calls to functions that do not not write to
207 <li>The link-time optimizer now runs the -prune-eh pass (to remove unused
208 exception handlers).</li>
210 <li>The -simplifycfg pass can now eliminate simple correlated branches (such as
211 "<tt>if (A < B && A < B)</tt>", and can turn short-circuiting
212 operators into the strict versions when useful (such as "<tt>if (A < B || A
213 > C)</tt>" into "<tt>if (A < B | A > C)</tt>"</li>
215 <li>LLVM now has infrastructure for (simple and sparse conditional) constant
216 propagation of function calls. It currently supports a few math library
217 functions like sqrt/sin/cos/etc.</li>
221 <!--=========================================================================-->
222 <div class="doc_subsubsection">
223 <a name="bugfix">In this release, the following bugs in the previous release
227 <div class="doc_text">
229 <p>Bugs in the LLVM Core:</p>
232 <li><a href="http://llvm.cs.uiuc.edu/PR330">[vmcore] Linker causes erroneous
234 <li><a href="http://llvm.cs.uiuc.edu/PR306">[loopsimplify] Loop simplify
235 incorrectly updates dominator information</a></li>
236 <li><a href="http://llvm.cs.uiuc.edu/PR310">[tailduplicate] DemoteRegToStack
237 breaks SSA form</a></li>
238 <li><a href="http://llvm.cs.uiuc.edu/PR313">[X86] JIT miscompiles unsigned short
239 to floating point cast</a></li>
240 <li><a href="http://llvm.cs.uiuc.edu/PR332">[adce] Crash handling unreachable
241 code that unwinds</a></li>
242 <li><a href="http://llvm.cs.uiuc.edu/PR333">[sparc] LLC can't emit 2 functions
243 of the same name, both having constant pools</a></li>
244 <li><a href="http://llvm.cs.uiuc.edu/PR337">[livevar] Live variables missed
245 physical register use of aliased definition</a></li>
246 <li><a href="http://llvm.cs.uiuc.edu/PR340">Verifier misses malformed switch instruction</a></li>
249 <p>Bugs in the C/C++ front-end:</p>
252 <li><a href="http://llvm.cs.uiuc.edu/PR326">[llvmgcc] Crash on use of undeclared
254 <li><a href="http://llvm.cs.uiuc.edu/PR298">[llvmgcc] Variable length array
255 indexing miscompiled</a></li>
259 <!-- *********************************************************************** -->
260 <div class="doc_section">
261 <a name="portability">Portability and Supported Platforms</a>
263 <!-- *********************************************************************** -->
265 <div class="doc_text">
267 <p>LLVM is known to work in the following platforms:</p>
270 <li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
271 other unix-like systems).</li>
272 <li>Sun UltraSPARC workstations running Solaris 8.</li>
273 <li>PowerPC-based Mac OS X boxes, running 10.3 and above (C backend and
274 interpreter only, no native codegen is available yet).</li>
275 <li>Intel and AMD machines running on Win32 with the Cygwin libraries.</li>
279 <p>The core LLVM infrastructure uses
280 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
281 to the machine and operating system on which it is built. However, minor
282 porting may be required to get LLVM to work on new platforms. We welcome your
283 portability patches and reports of successful builds or error messages.</p>
285 <p>Note that the LLVM build system does not currently support directories with
286 spaces on them when running on Win32/cygwin. We strongly recommend running
287 LLVM and the C frontend out of a top-level directory without spaces (e.g.,
288 <tt>/cygdrive/c/llvm</tt>).</p>
292 <!--=========================================================================-->
293 <div class="doc_subsection">
294 In this release, the following portability problems were fixed:
297 <div class="doc_text">
300 <li><a href="http://llvm.cs.uiuc.edu/PR304">warnings compiling Stacker compiler
302 <li><a href="http://llvm.cs.uiuc.edu/PR308">Archive file reader doesn't
303 understand abbreviated names in headers</a></li>
308 <!-- *********************************************************************** -->
309 <div class="doc_section">
310 <a name="knownproblems">Known Problems</a>
312 <!-- *********************************************************************** -->
314 <div class="doc_text">
316 <p>This section contains all known problems with the LLVM system, listed by
317 component. As new problems are discovered, they will be added to these
318 sections. If you run into a problem, please check the <a
319 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
320 there isn't already one.</p>
324 <!-- ======================================================================= -->
325 <div class="doc_subsection">
326 <a name="experimental">Experimental features included with this release</a>
329 <div class="doc_text">
331 <p>The following components of this LLVM release are either untested, known to
332 be broken or unreliable, or are in early development. These components should
333 not be relied on, and bugs should not be filed against them, but they may be
334 useful to some people. In particular, if you would like to work on one of these
335 components, please contact us on the llvmdev list.</p>
338 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
339 -ipmodref, -sortstructs, -swapstructs, -cee</tt></li>
341 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
342 it should) and not thoroughly tested.</li>
343 <li>The <tt>llvm-ar</tt> tool is incomplete and probably buggy.</li>
344 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
349 <!-- ======================================================================= -->
350 <div class="doc_subsection">
351 <a name="core">Known problems with the LLVM Core</a>
354 <div class="doc_text">
358 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not
361 <li>The JIT does not use mutexes to protect its internal data structures. As
362 such, execution of a threaded program could cause these data structures to be
365 <li>It is not possible to <tt>dlopen</tt> an LLVM bytecode file in the JIT.</li>
367 <li>Linking in static archive files (.a files) is very slow (there is no symbol
368 table in the archive).</li>
370 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
371 objects/archives in the order specified on the command line.</a></li>
373 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not mark
374 values live across a setjmp as volatile</a>. This missing feature only affects
375 targets whose setjmp/longjmp libraries do not save and restore the entire
380 <!-- ======================================================================= -->
381 <div class="doc_subsection">
382 <a name="c-fe">Known problems with the C front-end</a>
385 <!-- _______________________________________________________________________ -->
386 <div class="doc_subsubsection">Bugs</div>
388 <div class="doc_text">
390 <li>C99 Variable sized arrays do not release stack memory when they go out of
391 scope. Thus, the following program may run out of stack space:
393 for (i = 0; i != 1000000; ++i) {
399 <li>Initialization of global union variables can only be done <a
400 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
403 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
404 external function is re-declared as static</a></li>
409 <!-- _______________________________________________________________________ -->
410 <div class="doc_subsubsection">
414 <div class="doc_text">
418 <li>Inline assembly is not yet supported.</li>
420 <li>"long double" is transformed by the front-end into "double". There is no
421 support for floating point data types of any size other than 32 and 64
424 <li>The following Unix system functionality has not been tested and may not
427 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
428 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
429 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
430 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
431 - These functions have not been tested.
434 <li>Although many GCC extensions are supported, some are not. In particular,
435 the following extensions are known to <b>not be</b> supported:
437 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
438 <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>
439 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
440 <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>
441 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
442 <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>
443 <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>
444 <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>
445 <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>
446 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
447 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
450 <p>The following GCC extensions are <b>partially</b> supported. An ignored
451 attribute means that the LLVM compiler ignores the presence of the attribute,
452 but the code should still work. An unsupported attribute is one which is
453 ignored by the LLVM compiler and will cause a different interpretation of
457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
458 Arrays whose length is computed at run time.<br>
459 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
461 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
463 Declaring that functions have no side effects or that they can never
466 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
467 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
468 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
470 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
471 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
472 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
474 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
475 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
476 <tt>fastcall</tt>, all other target specific attributes</li>
478 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
479 Specifying attributes of variables.<br>
480 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
481 <tt>deprecated</tt>, <tt>transparent_union</tt>,
482 <tt>unused</tt>, <tt>weak</tt><br>
484 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
485 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
486 <tt>vector_size</tt>, <tt>dllimport</tt>,
487 <tt>dllexport</tt>, all target specific attributes.</li>
489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
490 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
491 <tt>deprecated</tt>, <tt>may_alias</tt><br>
493 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
494 all target specific attributes.</li>
496 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
497 Other built-in functions.<br>
498 We support all builtins which have a C language equivalent (e.g.,
499 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
500 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
501 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt> (ignored).</li>
505 <p>The following extensions <b>are</b> known to be supported:</p>
508 <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>
509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
510 <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>
511 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Lvalues.html#Lvalues">Lvalues</a>: Using <code>?:</code>, "<code>,</code>" and casts in lvalues.</li>
512 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
513 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
514 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
515 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
516 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
517 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
518 <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>
519 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
520 <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>
521 <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>
522 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
523 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
524 or arrays as values.</li>
525 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
526 <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>
527 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
528 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
529 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
530 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
532 <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>
533 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
534 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
535 <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>
536 <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>
537 <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>
538 <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>
539 <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>
540 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
545 <p>If you run into GCC extensions which have not been included in any of these
546 lists, please let us know (also including whether or not they work).</p>
550 <!-- ======================================================================= -->
551 <div class="doc_subsection">
552 <a name="c++-fe">Known problems with the C++ front-end</a>
555 <div class="doc_text">
557 <p>For this release, the C++ front-end is considered to be fully functional but
558 has not been tested as thoroughly as the C front-end. It has been tested and
559 works for a number of non-trivial programs, but there may be lurking bugs.
560 Please report any bugs or problems.</p>
564 <!-- _______________________________________________________________________ -->
565 <div class="doc_subsubsection">Bugs</div>
567 <div class="doc_text">
570 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
575 <!-- _______________________________________________________________________ -->
576 <div class="doc_subsubsection">
580 <div class="doc_text">
584 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
585 parser is significantly more standards compliant (and picky) than prior GCC
586 versions. For more information, see the C++ section of the <a
587 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
589 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
590 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
591 function and in the <tt>setjmp</tt> receiver function may not be run.
592 Objects in intervening stack frames will be destroyed, however (which is
593 better than most compilers).</li>
595 <li>The LLVM C++ front-end follows the <a
596 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
597 This document, which is not Itanium specific, specifies a standard for name
598 mangling, class layout, v-table layout, RTTI formats, and other C++
599 representation issues. Because we use this API, code generated by the LLVM
600 compilers should be binary compatible with machine code generated by other
601 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
602 <i>However</i>, the exception handling mechanism used by LLVM is very
603 different from the model used in the Itanium ABI, so <b>exceptions will not
604 interact correctly</b>. </li>
610 <!-- ======================================================================= -->
611 <div class="doc_subsection">
612 <a name="x86-be">Known problems with the X86 back-end</a>
615 <div class="doc_text">
623 <!-- ======================================================================= -->
624 <div class="doc_subsection">
625 <a name="sparc-be">Known problems with the Sparc back-end</a>
628 <div class="doc_text">
631 <li>There are several programs in the LLVM testsuite that the Sparc code generator is known to miscompile.</li>
636 <!-- ======================================================================= -->
637 <div class="doc_subsection">
638 <a name="c-be">Known problems with the C back-end</a>
641 <div class="doc_text">
645 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
646 Analysis rules. As such, special options may be necessary to compile the code
647 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
648 problem probably cannot be fixed.</li>
650 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
651 cannot include special floating point numbers like Not-A-Number or
654 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
655 supported</a>. This should not affect LLVM produced by the C or C++
662 <!-- *********************************************************************** -->
663 <div class="doc_section">
664 <a name="additionalinfo">Additional Information</a>
666 <!-- *********************************************************************** -->
668 <div class="doc_text">
670 <p>A wide variety of additional information is available on the LLVM web page,
671 including mailing lists and publications describing algorithms and components
672 implemented in LLVM. The web page also contains versions of the API
673 documentation which is up-to-date with the CVS version of the source code. You
674 can access versions of these documents specific to this release by going into
675 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
677 <p>If you have any questions or comments about LLVM, please feel free to contact
678 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
683 <!-- *********************************************************************** -->
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