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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>
154 <!--=========================================================================-->
155 <div class="doc_subsubsection">
156 In this release, the following missing features were implemented:
159 <div class="doc_text">
162 <li><a href="http://llvm.cs.uiuc.edu/PR419">JIT interface should support
165 <li>The <tt>llvm-ar</tt> tool was previously incomplete and didn't properly
166 support other ar(1) implementations. This has been corrected. <tt>llvm-ar</tt>
167 now fully supports all archive editing functions, table of contents listing,
168 extraction, and printing. It can also read BSD4.4/MacOSX and SVR4 style
169 archives. See <a href="CommandGuide/html/llvm-ar.html">llvm-ar</a> for
176 <!--=========================================================================-->
177 <div class="doc_subsubsection">
178 <a name="qualityofimp">In this release, the following Quality of Implementation
179 issues were fixed:</a>
182 <div class="doc_text">
185 <li><a href="http://llvm.cs.uiuc.edu/PR426">[llvmg++] Tons of warnings
186 are spewed when linking to libstdc++</a>
188 <li><a href="http://llvm.cs.uiuc.edu/PR352">include/{Support,Config} ->
189 include/llvm/{Support,Config}</a>
191 <li>The names of the libraries generated by compiling LLVM source have been
192 changed to ensure they do not conflict with other packages upon installation.
193 Each LLVM library is now prefixed with LLVM and uses mixed clase. For example,
194 the library <tt>libasmparser.a</tt> in 1.3 has become
195 <tt>libLLVMAsmParser.a</tt> in release 1.4.
197 <li><a href="http://llvm.cs.uiuc.edu/PR459">[llvmg++] C++ frontend is expanding
198 lots of unused inline functions</a></li>
203 <!--=========================================================================-->
204 <div class="doc_subsubsection">
205 In this release, the following build problems were fixed:
208 <div class="doc_text">
210 <li><a href="http://llvm.cs.uiuc.edu/PR256">[autoconf] further standardizing
211 autoconf usage</a>. Various improvements in the configure.ac script were
212 made as well as the makefile system.
217 <!--=========================================================================-->
218 <div class="doc_subsubsection">
219 <a name="codequality">This release includes the following Code Quality
223 <div class="doc_text">
225 <li><a href="http://llvm.cs.uiuc.edu/PR362">Ugly code generated for
226 std::min/std::max</a>
231 <!--=========================================================================-->
232 <div class="doc_subsubsection">
233 <a name="bugfix">In this release, the following bugs in the previous release
237 <div class="doc_text">
239 <p>Bugs fixed in the LLVM Core:</p>
242 <li><a href="http://llvm.cs.uiuc.edu/PR420">[licm] LICM invalidates alias
243 analysis info and uses broken information</a> (optimizer crash)</li>
244 <li><a href="http://llvm.cs.uiuc.edu/PR422">[asmwriter] Asmwriter is really
245 slow for functions with lots of values</a></li>
246 <li><a href="http://llvm.cs.uiuc.edu/PR423">[anders-aa] Andersen's AA is
247 completely broken in LLVM 1.3</a></li>
248 <li><a href="http://llvm.cs.uiuc.edu/PR430">[bcwriter] Empty compaction
249 tables defined</a></li>
250 <li><a href="http://llvm.cs.uiuc.edu/PR227">[X86] llc output for functions
251 w/certain names tickles GNU 'as' bugs</a></li>
254 <p>Bugs in the C/C++ front-end:</p>
257 <li><a href="http://llvm.cs.uiuc.edu/PR445">[llvmg++] not enough templates are
258 instantiated</a></li>
259 <li><a href="http://llvm.cs.uiuc.edu/PR450">[llvmg++] Extern const globals
260 cannot be marked 'constant' if they have nontrivial ctors or dtors</a></li>
261 <li><a href="http://llvm.cs.uiuc.edu/PR461">[llvmgcc] Crash compiling unnamed
262 bitfield which does not increase struct size</a></li>
263 <li><a href="http://llvm.cs.uiuc.edu/PR424">[llvmgcc] llvmgcc emits invalid
264 constant exprs</a></li>
265 <li><a href="http://llvm.cs.uiuc.edu/PR421">[llvmg++] Crash in initializing
266 array with constructors in hard EH situations</a></li>
269 <p>Bugs fixed in the Sparc V9 back-end:</p>
272 <li><a href="http://llvm.cs.uiuc.edu/PR428">[sparcv9] regalloc assertion
273 failure with certain indirect calls</a></li>
278 <!-- *********************************************************************** -->
279 <div class="doc_section">
280 <a name="portability">Portability and Supported Platforms</a>
282 <!-- *********************************************************************** -->
284 <div class="doc_text">
286 <p>LLVM is known to work in the following platforms:</p>
289 <li>Intel and AMD machines running Red Hat Linux and FreeBSD (and probably
290 other unix-like systems).</li>
291 <li>Sun UltraSPARC workstations running Solaris 8.</li>
292 <li>Intel and AMD machines running on Win32 with the Cygwin libraries.</li>
293 <li>PowerPC-based Mac OS X boxes, running 10.2 and above.</li>
296 <p>The core LLVM infrastructure uses
297 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
298 to the machine and operating system on which it is built. However, minor
299 porting may be required to get LLVM to work on new platforms. We welcome your
300 portability patches and reports of successful builds or error messages.</p>
302 <p>Note that the LLVM build system does not currently support directories with
303 spaces on them when running on Win32/cygwin. We strongly recommend running
304 LLVM and the C frontend out of a top-level directory without spaces (e.g.,
305 <tt>/cygdrive/c/llvm</tt>). Also, make sure to install <b>all</b> of the
306 cygwin packages. By default, many important tools are not installed that
307 are needed by the LLVM build process or test suite (e.g., /bin/time). Finally,
308 please make sure that there are no directories with spaces in them in your
309 PATH environment variable.</p>
313 <!-- *********************************************************************** -->
314 <div class="doc_section">
315 <a name="knownproblems">Known Problems</a>
317 <!-- *********************************************************************** -->
319 <div class="doc_text">
321 <p>This section contains all known problems with the LLVM system, listed by
322 component. As new problems are discovered, they will be added to these
323 sections. If you run into a problem, please check the <a
324 href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug database</a> and submit a bug if
325 there isn't already one.</p>
329 <!-- ======================================================================= -->
330 <div class="doc_subsection">
331 <a name="experimental">Experimental features included with this release</a>
334 <div class="doc_text">
336 <p>The following components of this LLVM release are either untested, known to
337 be broken or unreliable, or are in early development. These components should
338 not be relied on, and bugs should not be filed against them, but they may be
339 useful to some people. In particular, if you would like to work on one of these
340 components, please contact us on the llvmdev list.</p>
343 <li>The following passes are incomplete or buggy: <tt>-pgmdep, -memdep,
344 -ipmodref, -cee, -branch-combine, -instloops, -paths</tt></li>
345 <li>The <tt>-pre</tt> pass is incomplete (there are cases it doesn't handle that
346 it should) and not thoroughly tested.</li>
347 <li>The <tt>llvm-db</tt> tool is in a very early stage of development.</li>
352 <!-- ======================================================================= -->
353 <div class="doc_subsection">
354 <a name="core">Known problems with the LLVM Core</a>
357 <div class="doc_text">
360 <li>In the JIT, <tt>dlsym</tt> on a symbol compiled by the JIT will not work.
362 <li>The JIT does not use mutexes to protect its internal data structures. As
363 such, execution of a threaded program could cause these data structures to be
366 <li>Linking in static archive files (.a files) is slow by default because
367 there is no symbol table in the archive. To remedy this, run
368 <a href="CommandGuide/html/llvm-ranlib.html"><tt>llvm-ranlib</tt></a> on the
369 archive to add an LLVM symbol table.
371 <li>The gccld program <a href="http://llvm.cs.uiuc.edu/PR139">does not link
372 objects/archives in the order specified on the command line.</a>
374 <li><a href="http://llvm.cs.uiuc.edu/PR240">The lower-invoke pass does not
375 mark values live across a setjmp as volatile</a>. This missing feature
376 only affects targets whose setjmp/longjmp libraries do not save and restore
377 the entire register file.</li>
378 <li><a href="http://llvm.cs.uiuc.edu/PR427">[bytecode] Assertion on V1
379 Bytecode Files</a>. This bug won't be fixed because V1 bytecode had its own
380 problems, no one is using V1 bytecode any more, and the fix is non-trivial.
385 <!-- ======================================================================= -->
386 <div class="doc_subsection">
387 <a name="c-fe">Known problems with the C front-end</a>
390 <!-- _______________________________________________________________________ -->
391 <div class="doc_subsubsection">Bugs</div>
393 <div class="doc_text">
395 <li>C99 Variable sized arrays do not release stack memory when they go out of
396 scope. Thus, the following program may run out of stack space:
398 for (i = 0; i != 1000000; ++i) {
404 <li>Initialization of global union variables can only be done <a
405 href="http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=162">with the largest union
408 <li><a href="http://llvm.cs.uiuc.edu/PR244">[llvm-gcc] Error when an implicitly
409 external function is re-declared as static</a></li>
414 <!-- _______________________________________________________________________ -->
415 <div class="doc_subsubsection">
419 <div class="doc_text">
423 <li>Inline assembly is not yet supported.</li>
425 <li>"long double" is transformed by the front-end into "double". There is no
426 support for floating point data types of any size other than 32 and 64
429 <li>The following Unix system functionality has not been tested and may not
432 <li><tt>sigsetjmp</tt>, <tt>siglongjmp</tt> - These are not turned into the
433 appropriate <tt>invoke</tt>/<tt>unwind</tt> instructions. Note that
434 <tt>setjmp</tt> and <tt>longjmp</tt> <em>are</em> compiled correctly.
435 <li><tt>getcontext</tt>, <tt>setcontext</tt>, <tt>makecontext</tt>
436 - These functions have not been tested.
439 <li>Although many GCC extensions are supported, some are not. In particular,
440 the following extensions are known to <b>not be</b> supported:
442 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
443 <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>
444 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
445 <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>
446 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
447 <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>
448 <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>
449 <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>
450 <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>
451 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html#Thread-Local">Thread-Local</a>: Per-thread variables.</li>
452 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
455 <p>The following GCC extensions are <b>partially</b> supported. An ignored
456 attribute means that the LLVM compiler ignores the presence of the attribute,
457 but the code should still work. An unsupported attribute is one which is
458 ignored by the LLVM compiler and will cause a different interpretation of
462 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
463 Arrays whose length is computed at run time.<br>
464 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
466 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
468 Declaring that functions have no side effects or that they can never
471 <b>Supported:</b> <tt>format</tt>, <tt>format_arg</tt>, <tt>non_null</tt>,
472 <tt>constructor</tt>, <tt>destructor</tt>, <tt>unused</tt>,
473 <tt>deprecated</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
475 <b>Ignored:</b> <tt>noreturn</tt>, <tt>noinline</tt>,
476 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
477 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
479 <b>Unsupported:</b> <tt>used</tt>, <tt>section</tt>, <tt>alias</tt>,
480 <tt>visibility</tt>, <tt>regparm</tt>, <tt>stdcall</tt>,
481 <tt>fastcall</tt>, all other target specific attributes</li>
483 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
484 Specifying attributes of variables.<br>
485 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
486 <tt>deprecated</tt>, <tt>transparent_union</tt>,
487 <tt>unused</tt>, <tt>weak</tt><br>
489 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
490 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
491 <tt>vector_size</tt>, <tt>dllimport</tt>,
492 <tt>dllexport</tt>, all target specific attributes.</li>
494 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
495 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
496 <tt>deprecated</tt>, <tt>may_alias</tt><br>
498 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
499 all target specific attributes.</li>
501 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
502 Other built-in functions.<br>
503 We support all builtins which have a C language equivalent (e.g.,
504 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
505 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
506 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
507 (currently ignored). We also support builtins for ISO C99 floating
508 point comparison macros (e.g., <tt>__builtin_islessequal</tt>).</li>
511 <p>The following extensions <b>are</b> known to be supported:</p>
514 <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>
515 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
516 <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>
517 <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>
518 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
519 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
520 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
521 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
522 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
523 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
524 <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>
525 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
526 <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>
527 <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>
528 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
529 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
530 or arrays as values.</li>
531 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
532 <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>
533 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
534 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
535 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
536 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C---Comments.html#C++%20Comments">C++ Comments</a>: C++ comments are recognized.</li>
537 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
538 <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>
539 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
540 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
541 <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>
542 <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>
543 <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>
544 <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>
545 <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>
546 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
551 <p>If you run into GCC extensions which have not been included in any of these
552 lists, please let us know (also including whether or not they work).</p>
556 <!-- ======================================================================= -->
557 <div class="doc_subsection">
558 <a name="c++-fe">Known problems with the C++ front-end</a>
561 <div class="doc_text">
563 <p>For this release, the C++ front-end is considered to be fully functional but
564 has not been tested as thoroughly as the C front-end. It has been tested and
565 works for a number of non-trivial programs, but there may be lurking bugs.
566 Please report any bugs or problems.</p>
570 <!-- _______________________________________________________________________ -->
571 <div class="doc_subsubsection">Bugs</div>
573 <div class="doc_text">
576 <li>The C++ front-end inherits all problems afflicting the <a href="#c-fe">C
579 <li><b>IA-64 specific</b>: The C++ front-end does not use <a
580 href="http://llvm.cs.uiuc.edu/PR406">IA64 ABI compliant layout of v-tables</a>.
581 In particular, it just stores function pointers instead of function
582 descriptors in the vtable. This bug prevents mixing C++ code compiled with
583 LLVM with C++ objects compiled by other C++ compilers.</li>
589 <!-- _______________________________________________________________________ -->
590 <div class="doc_subsubsection">
594 <div class="doc_text">
598 <li>The C++ front-end is based on a pre-release of the GCC 3.4 C++ parser. This
599 parser is significantly more standards compliant (and picky) than prior GCC
600 versions. For more information, see the C++ section of the <a
601 href="http://gcc.gnu.org/gcc-3.4/changes.html">GCC 3.4 release notes</a>.</li>
603 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
604 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
605 function and in the <tt>setjmp</tt> receiver function may not be run.
606 Objects in intervening stack frames will be destroyed, however (which is
607 better than most compilers).</li>
609 <li>The LLVM C++ front-end follows the <a
610 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
611 This document, which is not Itanium specific, specifies a standard for name
612 mangling, class layout, v-table layout, RTTI formats, and other C++
613 representation issues. Because we use this API, code generated by the LLVM
614 compilers should be binary compatible with machine code generated by other
615 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
616 <i>However</i>, the exception handling mechanism used by LLVM is very
617 different from the model used in the Itanium ABI, so <b>exceptions will not
618 interact correctly</b>. </li>
624 <!-- ======================================================================= -->
625 <div class="doc_subsection">
626 <a name="x86-be">Known problems with the X86 back-end</a>
629 <div class="doc_text">
637 <!-- ======================================================================= -->
638 <div class="doc_subsection">
639 <a name="sparcv9-be">Known problems with the SparcV9 back-end</a>
642 <div class="doc_text">
645 <li><a href="http://llvm.cs.uiuc.edu/PR60">[sparcv9] SparcV9 backend miscompiles
646 several programs in the LLVM test suite</a></li>
651 <!-- ======================================================================= -->
652 <div class="doc_subsection">
653 <a name="ppc-be">Known problems with the PowerPC back-end</a>
656 <div class="doc_text">
664 <!-- ======================================================================= -->
665 <div class="doc_subsection">
666 <a name="c-be">Known problems with the C back-end</a>
669 <div class="doc_text">
673 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
674 Analysis rules. As such, special options may be necessary to compile the code
675 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
676 problem probably cannot be fixed.</li>
678 <li><a href="http://llvm.cs.uiuc.edu/PR33">Initializers for global variables</a>
679 cannot include special floating point numbers like Not-A-Number or
682 <li><a href="http://llvm.cs.uiuc.edu/PR56">Zero arg vararg functions are not
683 supported</a>. This should not affect LLVM produced by the C or C++
690 <!-- *********************************************************************** -->
691 <div class="doc_section">
692 <a name="additionalinfo">Additional Information</a>
694 <!-- *********************************************************************** -->
696 <div class="doc_text">
698 <p>A wide variety of additional information is available on the LLVM web page,
699 including mailing lists and publications describing algorithms and components
700 implemented in LLVM. The web page also contains versions of the API
701 documentation which is up-to-date with the CVS version of the source code. You
702 can access versions of these documents specific to this release by going into
703 the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
705 <p>If you have any questions or comments about LLVM, please feel free to contact
706 us via the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">mailing
711 <!-- *********************************************************************** -->
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