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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">
89 <li>LLVM now includes a JIT for the PowerPC target.</li>
90 <li>LLVM now optimizes global variables significantly more than it did
93 <li>LLVM now includes the new '<tt>undef</tt>' value and
94 <a href="LangRef.html#i_unreachable"><tt>unreachable</tt></a> instruction,
95 which give the optimizer more information about the behavior of the
98 <li>llvmgcc and llvmg++ now emit source line number information when '-g' is
99 passed in. This information can be used with llvm-db or other tools and
102 <li>The test/Programs hierarchy <a href="http://llvm.cs.uiuc.edu/PR257">has
103 been moved out of the main LLVM tree</a> into a separate CVS repository and
104 tarball. This shrinks the distribution size of LLVM itself significantly.
106 <li>Bytecode compression with bzip2 has been implemented. All bytecode files
107 generated by LLVM will now be compressed by default. Compression can be
108 disabled with the <tt>-disable-compression</tt> option to the tools that can
109 generate bytecode files.
111 <li>A generic <a href="http://llvm.cs.uiuc.edu/PR353">compiler driver</a> and
112 an associated <a href="CommandGuide/html/llvm-ld.html">generic linker</a> have
113 been implemented. The compiler driver is generic because it can be configured
114 to pre-process, translate, optimize, assemble, and link code from any source
115 language. This aids compiler writers because all that is needed is a
116 source-to-bytecode or source-to-assembly translator and a configuration file.
117 The linker is generic because it allows dynamically loadable optimization
118 modules to be executed for link-time optimization. Language specific
119 link-time optimization modules can be created and executed automatically.
121 <li>The <a href="http://llvm.cs.uiuc.edu/PR263">dependent libraries</a>
122 feature has been implemented. This allows front end compilers to indicate in
123 the bytecode which libraries the bytecode needs to be linked with. Both the
124 C/C++ front end and Stacker support generating the required libraries. The
125 Linker now supports using this information to ensure required libaries are
126 linked into the module. This minimizes the need to use the <tt>-l</tt> option
127 when using <a href="CommandGuide/html/llvmc.html"><tt>llvmc</tt></a>
129 <li>The LLVM makefiles have been improved to build LLVM faster (2x) and
130 includes new targets (like dist-check, uninstall). One important change is
131 associated with <a href="http://llvm.cs.uiuc.edu/PR456">PR456</a>. The
132 libraries and tools will now be built into <tt>$builddir/Debug/{bin,lib}</tt>
133 instead of <tt>$builddir/tools/Debug</tt> and <tt>$builddir/lib/Debug</tt>.
134 Similarly for <tt>Release</tt> and <tt>Profile</tt> builds.
136 <li>The LLVM source code is much more compatible with Microsoft Visual C++,
137 including the JIT and runtime-code generation, though the entire system
138 may not work with it.
140 <li>The target-to-JIT interfaces <a href="http://llvm.cs.uiuc.edu/PR283">are
141 now much simpler</a> and more powerful.
143 <li>zlib and libpng are <a href="http://llvm.cs.uiuc.edu/PR417">no longer
144 included in the main LLVM tarball</a>.</li>
145 <li>The LLVM code generator now generates asm writers for the target from
146 an abstract target description, instead of requiring them to be hand
148 <li>LLVM regression and feature tests can now be run with DejaGNU.</li>
149 <li>llvmgcc and llvmg++ now emit source-level line number information, making
150 it possible to map from LLVM code back to source. This is currently used
152 <li>Floating point intensive programs on X86 systems run much faster
153 with the LLC code generator and JIT than in 1.3.</li>
159 <!--=========================================================================-->
160 <div class="doc_subsubsection">
161 In this release, the following missing features were implemented:
164 <div class="doc_text">
167 <li><a href="http://llvm.cs.uiuc.edu/PR419">JIT interface should support
170 <li>The <tt>llvm-ar</tt> tool was previously incomplete and didn't properly
171 support other ar(1) implementations. This has been corrected. <tt>llvm-ar</tt>
172 now fully supports all archive editing functions, table of contents listing,
173 extraction, and printing. It can also read BSD4.4/MacOSX and SVR4 style
174 archives. See <a href="CommandGuide/html/llvm-ar.html">llvm-ar</a> for
181 <!--=========================================================================-->
182 <div class="doc_subsubsection">
183 <a name="qualityofimp">In this release, the following Quality of Implementation
184 issues were fixed:</a>
187 <div class="doc_text">
190 <li><a href="http://llvm.cs.uiuc.edu/PR426">[llvmg++] Tons of warnings
191 are spewed when linking to libstdc++</a>
193 <li><a href="http://llvm.cs.uiuc.edu/PR352">include/{Support,Config} ->
194 include/llvm/{Support,Config}</a>
196 <li>The names of the libraries generated by compiling LLVM source have been
197 changed to ensure they do not conflict with other packages upon installation.
198 Each LLVM library is now prefixed with LLVM and uses mixed clase. For example,
199 the library <tt>libasmparser.a</tt> in 1.3 has become
200 <tt>libLLVMAsmParser.a</tt> in release 1.4.
202 <li><a href="http://llvm.cs.uiuc.edu/PR459">[llvmg++] C++ frontend is expanding
203 lots of unused inline functions</a></li>
208 <!--=========================================================================-->
209 <div class="doc_subsubsection">
210 In this release, the following build problems were fixed:
213 <div class="doc_text">
215 <li><a href="http://llvm.cs.uiuc.edu/PR256">[autoconf] further standardizing
216 autoconf usage</a>. Various improvements in the configure.ac script were
217 made as well as the makefile system.
222 <!--=========================================================================-->
223 <div class="doc_subsubsection">
224 <a name="codequality">This release includes the following Code Quality
228 <div class="doc_text">
230 <li><a href="http://llvm.cs.uiuc.edu/PR362">Ugly code generated for
231 std::min/std::max</a>
236 <!--=========================================================================-->
237 <div class="doc_subsubsection">
238 <a name="bugfix">In this release, the following bugs in the previous release
242 <div class="doc_text">
244 <p>Bugs fixed in the LLVM Core:</p>
247 <li><a href="http://llvm.cs.uiuc.edu/PR420">[licm] LICM invalidates alias
248 analysis info and uses broken information</a> (optimizer crash)</li>
249 <li><a href="http://llvm.cs.uiuc.edu/PR422">[asmwriter] Asmwriter is really
250 slow for functions with lots of values</a></li>
251 <li><a href="http://llvm.cs.uiuc.edu/PR423">[anders-aa] Andersen's AA is
252 completely broken in LLVM 1.3</a></li>
253 <li><a href="http://llvm.cs.uiuc.edu/PR430">[bcwriter] Empty compaction
254 tables defined</a></li>
255 <li><a href="http://llvm.cs.uiuc.edu/PR227">[X86] llc output for functions
256 w/certain names tickles GNU 'as' bugs</a></li>
259 <p>Bugs in the C/C++ front-end:</p>
262 <li><a href="http://llvm.cs.uiuc.edu/PR445">[llvmg++] not enough templates are
263 instantiated</a></li>
264 <li><a href="http://llvm.cs.uiuc.edu/PR450">[llvmg++] Extern const globals
265 cannot be marked 'constant' if they have nontrivial ctors or dtors</a></li>
266 <li><a href="http://llvm.cs.uiuc.edu/PR461">[llvmgcc] Crash compiling unnamed
267 bitfield which does not increase struct size</a></li>
268 <li><a href="http://llvm.cs.uiuc.edu/PR424">[llvmgcc] llvmgcc emits invalid
269 constant exprs</a></li>
270 <li><a href="http://llvm.cs.uiuc.edu/PR421">[llvmg++] Crash in initializing
271 array with constructors in hard EH situations</a></li>
272 <li><a href="http://llvm.cs.uiuc.edu/PR397">[llvm-gcc] Inline function
273 redefinitions error due to 'asm' function rename</a></li>
274 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an
275 implicitly external function is re-declared as static</a></li>
276 <li><a href="http://llvm.cs.uiuc.edu/PR360">[llvmgcc] Structure field with
277 non-constant offset crashes llvmgcc</a></li>
278 <li><a href="http://llvm.cs.uiuc.edu/PR447">[llvmg++] Crash compiling
279 friend with default argument</a></li>
282 <p>Bugs fixed in the Sparc V9 back-end:</p>
285 <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
286 failure with certain indirect calls</a></li>
291 <!-- *********************************************************************** -->
292 <div class="doc_section">
293 <a name="portability">Portability and Supported Platforms</a>
295 <!-- *********************************************************************** -->
297 <div class="doc_text">
299 <p>LLVM is known to work in the following platforms:</p>
302 <li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
303 other unix-like systems).</li>
304 <li>Sun UltraSPARC workstations running Solaris 8.</li>
305 <li>Intel and AMD machines running on Win32 with the Cygwin libraries.</li>
306 <li>PowerPC-based Mac OS X boxes, running 10.2 and above.</li>
309 <p>The core LLVM infrastructure uses
310 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
311 to the machine and operating system on which it is built. However, minor
312 porting may be required to get LLVM to work on new platforms. We welcome your
313 portability patches and reports of successful builds or error messages.</p>
315 <p>Note that the LLVM build system does not currently support directories with
316 spaces on them when running on Win32/cygwin. We strongly recommend running
317 LLVM and the C frontend out of a top-level directory without spaces (e.g.,
318 <tt>/cygdrive/c/llvm</tt>). Also, make sure to install <b>all</b> of the
319 cygwin packages. By default, many important tools are not installed that
320 are needed by the LLVM build process or test suite (e.g., /bin/time). Finally,
321 please make sure that there are no directories with spaces in them in your
322 PATH environment variable.</p>
326 <!-- *********************************************************************** -->
327 <div class="doc_section">
328 <a name="knownproblems">Known Problems</a>
330 <!-- *********************************************************************** -->
332 <div class="doc_text">
334 <p>This section contains all known problems with the LLVM system, listed by
335 component. As new problems are discovered, they will be added to these
336 sections. If you run into a problem, please check the <a
337 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
338 there isn't already one.</p>
342 <!-- ======================================================================= -->
343 <div class="doc_subsection">
344 <a name="experimental">Experimental features included with this release</a>
347 <div class="doc_text">
349 <p>The following components of this LLVM release are either untested, known to
350 be broken or unreliable, or are in early development. These components should
351 not be relied on, and bugs should not be filed against them, but they may be
352 useful to some people. In particular, if you would like to work on one of these
353 components, please contact us on the llvmdev list.</p>
356 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
357 -ipmodref, -cee, -branch-combine, -instloops, -paths</tt></li>
358 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
359 it should) and not thoroughly tested.</li>
360 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
361 <li>The "iterative scan" register allocator (enabled with -regalloc=iterativescan)
367 <!-- ======================================================================= -->
368 <div class="doc_subsection">
369 <a name="core">Known problems with the LLVM Core</a>
372 <div class="doc_text">
375 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.
377 <li>The JIT does not use mutexes to protect its internal data structures. As
378 such, execution of a threaded program could cause these data structures to be
381 <li>Linking in static archive files (.a files) is slow by default because
382 there is no symbol table in the archive. To remedy this, run
383 <a href="CommandGuide/html/llvm-ranlib.html"><tt>llvm-ranlib</tt></a> on the
384 archive to add an LLVM symbol table.
386 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
387 objects/archives in the order specified on the command line.</a>
389 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
390 mark values live across a setjmp as volatile</a>. This missing feature
391 only affects targets whose setjmp/longjmp libraries do not save and restore
392 the entire register file.</li>
393 <li><a href="http://llvm.cs.uiuc.edu/PR427">[bytecode] Assertion on V1
394 Bytecode Files</a>. This bug won't be fixed because V1 bytecode had its own
395 problems, no one is using V1 bytecode any more, and the fix is non-trivial.
400 <!-- ======================================================================= -->
401 <div class="doc_subsection">
402 <a name="c-fe">Known problems with the C front-end</a>
405 <!-- _______________________________________________________________________ -->
406 <div class="doc_subsubsection">Bugs</div>
408 <div class="doc_text">
410 <li>C99 Variable sized arrays do not release stack memory when they go out of
411 scope. Thus, the following program may run out of stack space:
413 for (i = 0; i != 1000000; ++i) {
419 <li>Initialization of global union variables can only be done <a
420 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
423 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
424 external function is re-declared as static</a></li>
429 <!-- _______________________________________________________________________ -->
430 <div class="doc_subsubsection">
434 <div class="doc_text">
438 <li>Inline assembly is not yet supported.</li>
440 <li>"long double" is transformed by the front-end into "double". There is no
441 support for floating point data types of any size other than 32 and 64
444 <li>The following Unix system functionality has not been tested and may not
447 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
448 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
449 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
450 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
451 - These functions have not been tested.
454 <li>Although many GCC extensions are supported, some are not. In particular,
455 the following extensions are known to <b>not be</b> supported:
457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
458 <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>
459 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
460 <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>
461 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
462 <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>
463 <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>
464 <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>
465 <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>
466 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
467 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
470 <p>The following GCC extensions are <b>partially</b> supported. An ignored
471 attribute means that the LLVM compiler ignores the presence of the attribute,
472 but the code should still work. An unsupported attribute is one which is
473 ignored by the LLVM compiler and will cause a different interpretation of
477 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
478 Arrays whose length is computed at run time.<br>
479 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
481 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
483 Declaring that functions have no side effects or that they can never
486 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
487 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
488 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
490 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
491 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
492 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
494 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
495 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
496 <tt>fastcall</tt>, all other target specific attributes</li>
498 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
499 Specifying attributes of variables.<br>
500 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
501 <tt>deprecated</tt>, <tt>transparent_union</tt>,
502 <tt>unused</tt>, <tt>weak</tt><br>
504 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
505 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
506 <tt>vector_size</tt>, <tt>dllimport</tt>,
507 <tt>dllexport</tt>, all target specific attributes.</li>
509 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
510 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
511 <tt>deprecated</tt>, <tt>may_alias</tt><br>
513 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
514 all target specific attributes.</li>
516 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
517 Other built-in functions.<br>
518 We support all builtins which have a C language equivalent (e.g.,
519 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
520 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
521 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
522 (currently ignored). We also support builtins for ISO C99 floating
523 point comparison macros (e.g., <tt>__builtin_islessequal</tt>).</li>
526 <p>The following extensions <b>are</b> known to be supported:</p>
529 <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>
530 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
531 <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>
532 <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>
533 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
534 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
536 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
537 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
538 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
539 <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>
540 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
541 <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>
542 <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>
543 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
544 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
545 or arrays as values.</li>
546 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
547 <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>
548 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
549 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
550 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
551 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
552 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
553 <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>
554 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
555 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
556 <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>
557 <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>
558 <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>
559 <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>
560 <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>
561 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
566 <p>If you run into GCC extensions which have not been included in any of these
567 lists, please let us know (also including whether or not they work).</p>
571 <!-- ======================================================================= -->
572 <div class="doc_subsection">
573 <a name="c++-fe">Known problems with the C++ front-end</a>
576 <div class="doc_text">
578 <p>For this release, the C++ front-end is considered to be fully functional but
579 has not been tested as thoroughly as the C front-end. It has been tested and
580 works for a number of non-trivial programs, but there may be lurking bugs.
581 Please report any bugs or problems.</p>
585 <!-- _______________________________________________________________________ -->
586 <div class="doc_subsubsection">Bugs</div>
588 <div class="doc_text">
591 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
594 <li><b>IA-64 specific</b>: The C++ front-end does not use <a
595 href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
596 In particular, it just stores function pointers instead of function
597 descriptors in the vtable. This bug prevents mixing C++ code compiled with
598 LLVM with C++ objects compiled by other C++ compilers.</li>
604 <!-- _______________________________________________________________________ -->
605 <div class="doc_subsubsection">
609 <div class="doc_text">
613 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
614 parser is significantly more standards compliant (and picky) than prior GCC
615 versions. For more information, see the C++ section of the <a
616 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
618 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
619 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
620 function and in the <tt>setjmp</tt> receiver function may not be run.
621 Objects in intervening stack frames will be destroyed, however (which is
622 better than most compilers).</li>
624 <li>The LLVM C++ front-end follows the <a
625 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
626 This document, which is not Itanium specific, specifies a standard for name
627 mangling, class layout, v-table layout, RTTI formats, and other C++
628 representation issues. Because we use this API, code generated by the LLVM
629 compilers should be binary compatible with machine code generated by other
630 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
631 <i>However</i>, the exception handling mechanism used by LLVM is very
632 different from the model used in the Itanium ABI, so <b>exceptions will not
633 interact correctly</b>. </li>
639 <!-- ======================================================================= -->
640 <div class="doc_subsection">
641 <a name="x86-be">Known problems with the X86 back-end</a>
644 <div class="doc_text">
652 <!-- ======================================================================= -->
653 <div class="doc_subsection">
654 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
657 <div class="doc_text">
660 <li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
661 several programs in the LLVM test suite</a></li>
666 <!-- ======================================================================= -->
667 <div class="doc_subsection">
668 <a name="ppc-be">Known problems with the PowerPC back-end</a>
671 <div class="doc_text">
679 <!-- ======================================================================= -->
680 <div class="doc_subsection">
681 <a name="c-be">Known problems with the C back-end</a>
684 <div class="doc_text">
688 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
689 Analysis rules. As such, special options may be necessary to compile the code
690 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
691 problem probably cannot be fixed.</li>
693 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
694 cannot include special floating point numbers like Not-A-Number or
697 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
698 supported</a>. This should not affect LLVM produced by the C or C++
705 <!-- *********************************************************************** -->
706 <div class="doc_section">
707 <a name="additionalinfo">Additional Information</a>
709 <!-- *********************************************************************** -->
711 <div class="doc_text">
713 <p>A wide variety of additional information is available on the LLVM web page,
714 including mailing lists and publications describing algorithms and components
715 implemented in LLVM. The web page also contains versions of the API
716 documentation which is up-to-date with the CVS version of the source code. You
717 can access versions of these documents specific to this release by going into
718 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
720 <p>If you have any questions or comments about LLVM, please feel free to contact
721 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
726 <!-- *********************************************************************** -->
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