1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7 <title>LLVM 1.9 Release Notes</title>
11 <div class="doc_title">LLVM 1.9 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>
19 <li><a href="#additionalinfo">Additional Information</a></li>
22 <div class="doc_author">
23 <p>Written by the <a href="http://llvm.org">LLVM Team</a><p>
26 <!-- *********************************************************************** -->
27 <div class="doc_section">
28 <a name="intro">Introduction</a>
30 <!-- *********************************************************************** -->
32 <div class="doc_text">
34 <p>This document contains the release notes for the LLVM compiler
35 infrastructure, release 1.9. Here we describe the status of LLVM, including any
36 known problems and major improvements from the previous release. The most
37 up-to-date version of this document (corresponding to LLVM CVS) can be found
39 href="http://llvm.org/releases/">LLVM releases web site</a>. If you are
40 not reading this on the LLVM web pages, you should probably go there because
41 this document may be updated after the release.</p>
43 <p>For more information about LLVM, including information about the latest
44 release, please check out the <a href="http://llvm.org/">main LLVM
45 web site</a>. If you have questions or comments, the <a
46 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
47 list</a> is a good place to send them.</p>
49 <p>Note that if you are reading this file from CVS or the main LLVM web page,
50 this document applies to the <i>next</i> release, not the current one. To see
51 the release notes for the current or previous releases, see the <a
52 href="http://llvm.org/releases/">releases page</a>.</p>
56 <!-- *********************************************************************** -->
57 <div class="doc_section">
58 <a name="whatsnew">What's New?</a>
60 <!-- *********************************************************************** -->
62 <div class="doc_text">
64 <p>This is the tenth public release of the LLVM Compiler Infrastructure. This
65 release incorporates a large number of enhancements, new features, and bug
66 fixes. We recommend that all users of previous LLVM versions upgrade.
71 <!--=========================================================================-->
72 <div class="doc_subsection">
73 <a name="newfeatures">New Features in LLVM 1.9</a>
76 <!--_________________________________________________________________________-->
77 <div class="doc_subsubsection"><a name="x86-64">New X86-64 Backend</a></div>
78 <div class="doc_text">
79 <p>LLVM 1.9 now fully supports the x86-64 instruction set on Mac OS/X, and
80 supports it on Linux (and other operating systems) when compiling in -static
81 mode. LLVM includes JIT support for X86-64, and supports both Intel EMT-64T
82 and AMD-64 architectures. The X86-64 instruction set permits addressing a
83 64-bit addressing space and provides the compiler with twice the
84 number of integer registers to use.</p>
87 <!--_________________________________________________________________________-->
88 <div class="doc_subsubsection"><a name="lto">Link-Time Optimization integration
89 with native linkers</a></div>
90 <div class="doc_text">
91 <p>LLVM now includes <a href="LinkTimeOptimization.html">liblto</a> which can
92 be used to integrate LLVM Link-Time Optimization support into a native linker.
93 This allows LLVM .bc to transparently participate with linking an application,
94 even when some .o files are in LLVM form and some are not.</p>
97 <!--_________________________________________________________________________-->
98 <div class="doc_subsubsection"><a name="dwarf">DWARF debugging
99 support for Linux, Cygwin and MinGW on X86</a></div>
100 <div class="doc_text">
101 <p>llvm-gcc4 now supports generating debugging info for Linux, Cygwin and MinGW.
102 This extends the PPC/Darwin and X86/Darwin debugging support available in the
103 1.8 release. DWARF is a standard debugging format used on many platforms.</p>
106 <!--_________________________________________________________________________-->
107 <div class="doc_subsubsection"><a name="optimizer">Optimizer
108 Improvements</a></div>
109 <div class="doc_text">
110 <p>The mid-level optimizer is now faster and produces better code in many cases.
111 Significant changes include:</p>
114 <li>LLVM includes a new 'predicate simplifier' pass, which
115 currently performs dominator tree-based optimizations.</li>
116 <li>The complete loop unroll pass now supports unrolling of
117 multiple basic block loops.</li>
118 <li>The 'globalopt' pass can now perform the scalar replacement of
119 aggregates transformation on some heap allocations.</li>
120 <li>The globalsmodref-aa alias analysis can now track 'indirect pointer
121 globals' more accurately.</li>
122 <li>The instruction combiner can now perform element propagation
123 analysis of vector expressions, eliminating computation of vector elements
124 that are not used.</li>
129 <!--_________________________________________________________________________-->
130 <div class="doc_subsubsection"><a name="codegen">Code
131 Generator Enhancements</a></div>
133 <div class="doc_text">
135 The LLVM Target-Independent code generator now supports more target features and
136 optimizes many cases more aggressively. New features include:
140 <li>LLVM now includes a late branch folding pass which optimizes code
141 layout, performs several branch optzns, and deletes unreachable code.</li>
142 <li>The code generator now support targets that have pre/post-increment
143 addressing modes.</li>
144 <li>LLVM now supports dynamically-loadable register allocators and
146 <li>LLVM 1.9 includes several improvements to inline asm support,
147 including support for new constraints and modifiers.</li>
148 <li>The register coalescer is now more aggressive than before,
149 allowing it to eliminate more copies.</li>
152 <p>In addition, the LLVM target description format has itself been extended in
156 <li>tblgen now allows definition of '<a
157 href="TableGenFundamentals.html#multiclass">multiclasses</a>' which can be
158 used to factor instruction patterns more aggressively in .td files.</li>
159 <li>LLVM has a new TargetAsmInfo class which captures a variety of
160 information about the target assembly language format.</li>
161 <li>.td files now support "<tt>${:foo}</tt>" syntax for encoding
162 subtarget-specific assembler syntax into instruction descriptions.</li>
165 <p>Further, several significant target-specific enhancements are included in
169 <li>The LLVM ARM backend now supports more instructions
170 and the use of a frame pointer. It is now possible to build
171 libgcc and a simple cross compiler, but it is not considered "complete" yet.
173 <li>LLVM supports the Win32 dllimport/dllexport linkage and
174 stdcall/fastcall calling conventions.</li>
179 <!--_________________________________________________________________________-->
180 <div class="doc_subsubsection"><a name="other">Other Improvements</a></div>
181 <div class="doc_text">
182 <p>This release includes many other improvements, including improvements to
183 the optimizers and code generators (improving the generated code) changes to
184 speed up the compiler in many ways (improving algorithms and fine tuning
185 code), and changes to reduce the code size of the compiler itself.</p>
187 <p>More specific changes include:</p>
190 <li>The llvm-test framework now supports SPEC2006.</li>
191 <li>LLVM now includes a <a href="GetElementPtr.html">FAQ about the
192 <tt>getelementptr</tt> instruction</a>.</li>
193 <li>Bugpoint now supports a new "<tt>-find-bugs</tt>" mode. This mode makes
194 bugpoint permute pass sequences to try to expose bugs due to pass
196 <li>The JIT now supports lazily streaming code from multiple modules at a
197 time, implicitly linking the code as it goes.</li>
201 <!--=========================================================================-->
202 <div class="doc_subsection">
203 <a name="apichanges">Significant API Changes in LLVM 1.9</a>
206 <div class="doc_text">
208 <p>Several significant API changes have been made. If you are maintaining
209 out-of-tree code, please be aware that:</p>
212 <li>The ConstantSInt and ConstantUInt classes have been merged into the
213 ConstantInt class.</li>
214 <li><p>As a step towards making LLVM's integer types signless, several new
215 instructions have been added to LLVM. The <tt>Div</tt> instruction is now
216 <tt>UDiv</tt>, <tt>SDiv</tt>, and <tt>FDiv</tt>. The <tt>Rem</tt> instruction
217 is now <tt>URem</tt>, <tt>SRem</tt> and <tt>FRem</tt>. See the
218 <a href="LangRef.html">Language Reference</a> for details on these new
220 <li><p><tt>ConstantBool::True</tt> and <tt>ConstantBool::False</tt> have been
221 renamed to <tt>ConstantBool::getTrue()</tt> and
222 <tt>ConstantBool::getFalse()</tt>.</p></li>
223 <li>The 'analyze' tool has been merged into the 'opt' tool.</li>
229 <!-- *********************************************************************** -->
230 <div class="doc_section">
231 <a name="portability">Portability and Supported Platforms</a>
233 <!-- *********************************************************************** -->
235 <div class="doc_text">
237 <p>LLVM is known to work on the following platforms:</p>
240 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
241 (and probably other unix-like systems).</li>
242 <li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
243 <li>Sun UltraSPARC workstations running Solaris 8.</li>
244 <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
245 support is available for native builds with Visual C++).</li>
246 <li>PowerPC and X86-based Mac OS X systems, running 10.2 and above in 32-bit and
248 <li>Alpha-based machines running Debian GNU/Linux.</li>
249 <li>Itanium-based machines running Linux and HP-UX.</li>
252 <p>The core LLVM infrastructure uses
253 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
254 to the machine and operating system on which it is built. However, minor
255 porting may be required to get LLVM to work on new platforms. We welcome your
256 portability patches and reports of successful builds or error messages.</p>
260 <!-- *********************************************************************** -->
261 <div class="doc_section">
262 <a name="knownproblems">Known Problems</a>
264 <!-- *********************************************************************** -->
266 <div class="doc_text">
268 <p>This section contains all known problems with the LLVM system, listed by
269 component. As new problems are discovered, they will be added to these
270 sections. If you run into a problem, please check the <a
271 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
272 there isn't already one.</p>
276 <!-- ======================================================================= -->
277 <div class="doc_subsection">
278 <a name="experimental">Experimental features included with this release</a>
281 <div class="doc_text">
283 <p>The following components of this LLVM release are either untested, known to
284 be broken or unreliable, or are in early development. These components should
285 not be relied on, and bugs should not be filed against them, but they may be
286 useful to some people. In particular, if you would like to work on one of these
287 components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
290 <li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in in a
292 <li>The IA64 code generator is experimental.</li>
293 <li>The ARM code generator is experimental.</li>
294 <li>The Alpha JIT is experimental.</li>
295 <li>"<tt>-filetype=asm</tt>" (the default) is the only supported value for the
296 <tt>-filetype</tt> llc option.</li>
301 <!-- ======================================================================= -->
302 <div class="doc_subsection">
303 <a name="x86-be">Known problems with the X86 back-end</a>
306 <div class="doc_text">
309 <li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
310 assembly that uses the X86 floating point stack</a>. See the <a
311 href="http://llvm.org/PR879">bug</a> for details on workarounds on
317 <!-- ======================================================================= -->
318 <div class="doc_subsection">
319 <a name="ppc-be">Known problems with the PowerPC back-end</a>
322 <div class="doc_text">
325 <li><a href="http://llvm.org/PR642">PowerPC backend does not correctly
326 implement ordered FP comparisons</a>.</li>
327 <li>The 64-bit PowerPC backend is not fully stable. If you desire PPC64 support,
328 please use mainline CVS LLVM, which has several important bug fixes.</li>
333 <!-- ======================================================================= -->
334 <div class="doc_subsection">
335 <a name="sparc-be">Known problems with the SPARC back-end</a>
338 <div class="doc_text">
341 <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
342 support the 64-bit SPARC ABI (-m64).</li>
347 <!-- ======================================================================= -->
348 <div class="doc_subsection">
349 <a name="c-be">Known problems with the C back-end</a>
352 <div class="doc_text">
356 <li>The C back-end produces code that violates the ANSI C Type-Based Alias
357 Analysis rules. As such, special options may be necessary to compile the code
358 (for example, GCC requires the <tt>-fno-strict-aliasing</tt> option). This
359 problem probably cannot be fixed.</li>
361 <li><a href="http://llvm.org/PR56">Zero arg vararg functions are not
362 supported</a>. This should not affect LLVM produced by the C or C++
365 <li>The C backend does not correctly implement the <a
366 href="LangRef.html#i_stacksave"><tt>llvm.stacksave</tt></a> or
367 <a href="LangRef.html#i_stackrestore"><tt>llvm.stackrestore</tt></a>
368 intrinsics. This means that some code compiled by it can run out of stack
369 space if they depend on these (e.g. C99 varargs).</li>
371 <li><a href="http://llvm.org/PR802">The C backend does not support inline
372 assembly code</a>.</li>
377 <!-- ======================================================================= -->
378 <div class="doc_subsection">
379 <a name="alpha-be">Known problems with the Alpha back-end</a>
382 <div class="doc_text">
386 <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
387 appropriate nops inserted to ensure restartability.</li>
392 <!-- ======================================================================= -->
393 <div class="doc_subsection">
394 <a name="ia64-be">Known problems with the IA64 back-end</a>
397 <div class="doc_text">
401 <li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
402 made where the argument is not 16-byte aligned, as required on IA64. (Strictly
403 speaking this is not a bug in the IA64 back-end; it will also be encountered
404 when building C++ programs using the C back-end.)</li>
406 <li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
407 ABI compliant layout of v-tables</a>. In particular, it just stores function
408 pointers instead of function descriptors in the vtable. This bug prevents
409 mixing C++ code compiled with LLVM with C++ objects compiled by other C++
412 <li>There are a few ABI violations which will lead to problems when mixing LLVM
413 output with code built with other compilers, particularly for floating-point
416 <li>Defining vararg functions is not supported (but calling them is ok).</li>
422 <!-- ======================================================================= -->
423 <div class="doc_subsection">
424 <a name="arm-be">Known problems with the ARM back-end</a>
427 <div class="doc_text">
430 <li>The ARM backend is currently in early development stages, it is not
431 ready for production use.</li>
436 <!-- ======================================================================= -->
437 <div class="doc_subsection">
438 <a name="core">Known problems with the LLVM Core</a>
441 <div class="doc_text">
444 <li>In the JIT, <tt>dlsym()</tt> on a symbol compiled by the JIT will not
449 <!-- ======================================================================= -->
450 <div class="doc_subsection">
451 <a name="c-fe">Known problems with the C front-end</a>
454 <!-- _______________________________________________________________________ -->
455 <div class="doc_subsubsection">Bugs</div>
457 <div class="doc_text">
461 <p>llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but
462 does not currently support <a href="http://llvm.org/PR869">Link-Time
463 Optimization</a> or <a href="http://llvm.org/PR870">C++ Exception Handling</a>,
464 which llvm-gcc3 does.</p>
466 <p>llvm-gcc4 does not support the <a href="http://llvm.org/PR947">GCC indirect
467 goto extension</a>, but llvm-gcc3 does.</p>
471 <!-- _______________________________________________________________________ -->
472 <div class="doc_subsubsection">
476 <div class="doc_text">
480 <li>"long double" is transformed by the front-end into "double". There is no
481 support for floating point data types of any size other than 32 and 64
484 <li>Although many GCC extensions are supported, some are not. In particular,
485 the following extensions are known to <b>not be</b> supported:
487 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
488 <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>
489 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</li>
490 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
491 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
494 <p>The following GCC extensions are <b>partially</b> supported. An ignored
495 attribute means that the LLVM compiler ignores the presence of the attribute,
496 but the code should still work. An unsupported attribute is one which is
497 ignored by the LLVM compiler and will cause a different interpretation of
501 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
502 Arrays whose length is computed at run time.<br>
503 Supported, but allocated stack space is not freed until the function returns (noted above).</li>
505 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
507 Declaring that functions have no side effects or that they can never
510 <b>Supported:</b> <tt>constructor</tt>, <tt>destructor</tt>,
511 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
512 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noreturn</tt>,
513 <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
514 <tt>warn_unused_result</tt>, <tt>weak</tt><br>
516 <b>Ignored:</b> <tt>noinline</tt>,
517 <tt>always_inline</tt>, <tt>pure</tt>, <tt>const</tt>, <tt>nothrow</tt>,
518 <tt>malloc</tt>, <tt>no_instrument_function</tt>, <tt>cdecl</tt><br>
520 <b>Unsupported:</b> <tt>section</tt>, <tt>alias</tt>,
521 <tt>visibility</tt>, <tt>regparm</tt>, all other target specific
524 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
525 Specifying attributes of variables.<br>
526 <b>Supported:</b> <tt>cleanup</tt>, <tt>common</tt>, <tt>nocommon</tt>,
527 <tt>deprecated</tt>, <tt>dllimport</tt>,
528 <tt>dllexport</tt>, <tt>transparent_union</tt>,
529 <tt>unused</tt>, <tt>used</tt>, <tt>weak</tt><br>
531 <b>Unsupported:</b> <tt>aligned</tt>, <tt>mode</tt>, <tt>packed</tt>,
532 <tt>section</tt>, <tt>shared</tt>, <tt>tls_model</tt>,
533 <tt>vector_size</tt>, all target specific attributes.
536 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.<br>
537 <b>Supported:</b> <tt>transparent_union</tt>, <tt>unused</tt>,
538 <tt>deprecated</tt>, <tt>may_alias</tt><br>
540 <b>Unsupported:</b> <tt>aligned</tt>, <tt>packed</tt>,
541 all target specific attributes.</li>
543 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
544 Other built-in functions.<br>
545 We support all builtins which have a C language equivalent (e.g.,
546 <tt>__builtin_cos</tt>), <tt>__builtin_alloca</tt>,
547 <tt>__builtin_types_compatible_p</tt>, <tt>__builtin_choose_expr</tt>,
548 <tt>__builtin_constant_p</tt>, and <tt>__builtin_expect</tt>
549 (currently ignored). We also support builtins for ISO C99 floating
550 point comparison macros (e.g., <tt>__builtin_islessequal</tt>),
551 <tt>__builtin_prefetch</tt>, <tt>__builtin_popcount[ll]</tt>,
552 <tt>__builtin_clz[ll]</tt>, and <tt>__builtin_ctz[ll]</tt>.</li>
555 <p>The following extensions <b>are</b> known to be supported:</p>
558 <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>
559 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
560 <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>
561 <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>
562 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
563 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
564 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
565 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
566 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
567 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
568 <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>
569 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
570 <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>
571 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
572 <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>
573 <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>
574 <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>
575 <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>
576 <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>
577 <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>
578 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
579 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
580 or arrays as values.</li>
581 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
582 <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>
583 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
584 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
585 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
586 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Comments.html#C_002b_002b-Comments">C++ Comments</a>: C++ comments are recognized.</li>
587 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
588 <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>
589 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
590 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
591 <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>
592 <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>
593 <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>
594 <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>
595 <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>
596 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
601 <p>If you run into GCC extensions which have not been included in any of these
602 lists, please let us know (also including whether or not they work).</p>
606 <!-- ======================================================================= -->
607 <div class="doc_subsection">
608 <a name="c++-fe">Known problems with the C++ front-end</a>
611 <div class="doc_text">
613 <p>For this release, the C++ front-end is considered to be fully
614 tested and works for a number of non-trivial programs, including LLVM
619 <!-- _______________________________________________________________________ -->
620 <div class="doc_subsubsection">
624 <div class="doc_text">
626 <li>llvm-gcc4 does not support C++ exception handling at all yet.</li>
628 <li>Destructors for local objects are not always run when a <tt>longjmp</tt> is
629 performed. In particular, destructors for objects in the <tt>longjmp</tt>ing
630 function and in the <tt>setjmp</tt> receiver function may not be run.
631 Objects in intervening stack frames will be destroyed, however (which is
632 better than most compilers).</li>
634 <li>The LLVM C++ front-end follows the <a
635 href="http://www.codesourcery.com/cxx-abi">Itanium C++ ABI</a>.
636 This document, which is not Itanium specific, specifies a standard for name
637 mangling, class layout, v-table layout, RTTI formats, and other C++
638 representation issues. Because we use this API, code generated by the LLVM
639 compilers should be binary compatible with machine code generated by other
640 Itanium ABI C++ compilers (such as G++, the Intel and HP compilers, etc).
641 <i>However</i>, the exception handling mechanism used by llvm-gcc3 is very
642 different from the model used in the Itanium ABI, so <b>exceptions will not
643 interact correctly</b>. </li>
651 <!-- *********************************************************************** -->
652 <div class="doc_section">
653 <a name="additionalinfo">Additional Information</a>
655 <!-- *********************************************************************** -->
657 <div class="doc_text">
659 <p>A wide variety of additional information is available on the <a
660 href="http://llvm.org">LLVM web page</a>, including <a
661 href="http://llvm.org/docs/">documentation</a> and <a
662 href="http://llvm.org/pubs/">publications describing algorithms and
663 components implemented in LLVM</a>. The web page also contains versions of the
664 API documentation which is up-to-date with the CVS version of the source code.
665 You can access versions of these documents specific to this release by going
666 into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
668 <p>If you have any questions or comments about LLVM, please feel free to contact
669 us via the <a href="http://llvm.org/docs/#maillist"> mailing
674 <!-- *********************************************************************** -->
678 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
679 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
680 <a href="http://validator.w3.org/check/referer"><img
681 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
683 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
684 Last modified: $Date$