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11 <div class="doc_title">LLVM 2.2 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 2.2. Here we describe the status of LLVM, including
36 major improvements from the previous release and any known problems. All LLVM
37 releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
38 releases web site</a>.</p>
40 <p>For more information about LLVM, including information about the latest
41 release, please check out the <a href="http://llvm.org/">main LLVM
42 web site</a>. If you have questions or comments, the <a
43 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM developer's mailing
44 list</a> is a good place to send them.</p>
46 <p>Note that if you are reading this file from a Subversion checkout or the
47 main LLVM web page, this document applies to the <i>next</i> release, not the
48 current one. To see the release notes for a specific releases, please see the
49 <a href="http://llvm.org/releases/">releases page</a>.</p>
53 <!-- *********************************************************************** -->
54 <div class="doc_section">
55 <a name="whatsnew">What's New?</a>
57 <!-- *********************************************************************** -->
59 <div class="doc_text">
61 <p>This is the thirteenth public release of the LLVM Compiler Infrastructure.
62 It includes many features and refinements from LLVM 2.1.</p>
66 <!--=========================================================================-->
67 <div class="doc_subsection">
68 <a name="frontends">llvm-gcc 4.0, llvm-gcc 4.2, and clang</a>
71 <div class="doc_text">
73 <p>LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in
74 LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end
75 has made leaps and bounds and is now at least as good as 4.0 in virtually every
76 area, and is better in several areas (for example, exception handling
77 correctness). We strongly recommend that you migrate from llvm-gcc 4.0 to
78 llvm-gcc 4.2 in this release cycle because <b>LLVM 2.2 is the last release
79 that will support llvm-gcc 4.0</b>: LLVM 2.3 will only support the llvm-gcc
82 <p>The <a href="http://clang.llvm.org/">clang project</a> is an effort
83 to build a set of new front-end technology for the LLVM optimizer and code
84 generator. Currently, its C and Objective-C support is maturing nicely, and it
85 has advanced source-to-source analysis and transformation capabilities. If you
86 are interested in building source-level tools for C and Objective-C (and
87 eventually C++), you should take a look. However, note that clang is not an
88 official part of the LLVM 2.2 release. If you are interested in this project,
89 please see the web site and check it out from SVN head.</p>
93 <!--=========================================================================-->
94 <div class="doc_subsection">
95 <a name="optimizer">Optimizer Improvements</a>
98 <div class="doc_text">
100 <p>Some of the most noticable feature improvements this release have been in the
101 optimizer, speeding it up and making it more aggressive. For example:</p>
111 <!--=========================================================================-->
112 <div class="doc_subsection">
113 <a name="codegen">Code Generator Improvements</a>
116 <div class="doc_text">
118 <p>One of the main focuses of this release was performance tuning and bug
119 fixing. In addition to these, several new major changes occurred:</p>
130 <!--=========================================================================-->
131 <div class="doc_subsection">
132 <a name="targetspecific">Target Specific Improvements</a>
135 <div class="doc_text">
136 <p>New features include:
146 <!--=========================================================================-->
147 <div class="doc_subsection">
148 <a name="llvmgccimprovements">llvm-gcc Improvements</a>
151 <div class="doc_text">
152 <p>New features include:
162 <!--=========================================================================-->
163 <div class="doc_subsection">
164 <a name="coreimprovements">LLVM Core Improvements</a>
167 <div class="doc_text">
168 <p>New features include:
177 <!--=========================================================================-->
178 <div class="doc_subsection">
179 <a name="otherimprovements">Other Improvements</a>
182 <div class="doc_text">
183 <p>New features include:
192 <!-- *********************************************************************** -->
193 <div class="doc_section">
194 <a name="portability">Portability and Supported Platforms</a>
196 <!-- *********************************************************************** -->
198 <div class="doc_text">
200 <p>LLVM is known to work on the following platforms:</p>
203 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
204 (and probably other unix-like systems).</li>
205 <li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
207 <li>Intel and AMD machines running on Win32 using MinGW libraries (native)</li>
208 <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
209 support is available for native builds with Visual C++).</li>
210 <li>Sun UltraSPARC workstations running Solaris 8.</li>
211 <li>Alpha-based machines running Debian GNU/Linux.</li>
212 <li>Itanium-based machines running Linux and HP-UX.</li>
215 <p>The core LLVM infrastructure uses
216 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
217 to the machine and operating system on which it is built. However, minor
218 porting may be required to get LLVM to work on new platforms. We welcome your
219 portability patches and reports of successful builds or error messages.</p>
223 <!-- *********************************************************************** -->
224 <div class="doc_section">
225 <a name="knownproblems">Known Problems</a>
227 <!-- *********************************************************************** -->
229 <div class="doc_text">
231 <p>This section contains all known problems with the LLVM system, listed by
232 component. As new problems are discovered, they will be added to these
233 sections. If you run into a problem, please check the <a
234 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
235 there isn't already one.</p>
239 <!-- ======================================================================= -->
240 <div class="doc_subsection">
241 <a name="experimental">Experimental features included with this release</a>
244 <div class="doc_text">
246 <p>The following components of this LLVM release are either untested, known to
247 be broken or unreliable, or are in early development. These components should
248 not be relied on, and bugs should not be filed against them, but they may be
249 useful to some people. In particular, if you would like to work on one of these
250 components, please contact us on the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
253 <li>The <tt>-cee</tt> pass is known to be buggy, and may be removed in a
255 <li>The MSIL, IA64, Alpha, and MIPS backends are experimental.</li>
256 <li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
257 value for this option.</li>
258 <li>The llvmc tool is not supported.</li>
263 <!-- ======================================================================= -->
264 <div class="doc_subsection">
265 <a name="x86-be">Known problems with the X86 back-end</a>
268 <div class="doc_text">
271 <li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
272 assembly that uses the X86 floating point stack</a>.</li>
273 <li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
274 problems</a> on operating systems that don't require 16-byte stack alignment
275 (including most non-darwin OS's like linux).</li>
280 <!-- ======================================================================= -->
281 <div class="doc_subsection">
282 <a name="ppc-be">Known problems with the PowerPC back-end</a>
285 <div class="doc_text">
288 <li>The Linux PPC32/ABI support needs testing for the interpreter and static
289 compilation, and lacks support for debug information.</li>
294 <!-- ======================================================================= -->
295 <div class="doc_subsection">
296 <a name="arm-be">Known problems with the ARM back-end</a>
299 <div class="doc_text">
302 <li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
303 processors, thumb programs can crash or produce wrong
304 results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
305 <li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
307 <li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
308 programs compiled with LLVM. Please use more recent versions of QEMU.</li>
313 <!-- ======================================================================= -->
314 <div class="doc_subsection">
315 <a name="sparc-be">Known problems with the SPARC back-end</a>
318 <div class="doc_text">
321 <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
322 support the 64-bit SPARC ABI (-m64).</li>
327 <!-- ======================================================================= -->
328 <div class="doc_subsection">
329 <a name="alpha-be">Known problems with the Alpha back-end</a>
332 <div class="doc_text">
336 <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
337 appropriate nops inserted to ensure restartability.</li>
342 <!-- ======================================================================= -->
343 <div class="doc_subsection">
344 <a name="ia64-be">Known problems with the IA64 back-end</a>
347 <div class="doc_text">
351 <li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
352 made where the argument is not 16-byte aligned, as required on IA64. (Strictly
353 speaking this is not a bug in the IA64 back-end; it will also be encountered
354 when building C++ programs using the C back-end.)</li>
356 <li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
357 ABI compliant layout of v-tables</a>. In particular, it just stores function
358 pointers instead of function descriptors in the vtable. This bug prevents
359 mixing C++ code compiled with LLVM with C++ objects compiled by other C++
362 <li>There are a few ABI violations which will lead to problems when mixing LLVM
363 output with code built with other compilers, particularly for floating-point
366 <li>Defining vararg functions is not supported (but calling them is ok).</li>
368 <li>The Itanium backend has bitrotted somewhat.</li>
373 <!-- ======================================================================= -->
374 <div class="doc_subsection">
375 <a name="c-be">Known problems with the C back-end</a>
378 <div class="doc_text">
381 <li><a href="http://llvm.org/PR802">The C backend does not support inline
382 assembly code</a>.</li>
383 <li><a href="http://llvm.org/PR1126">The C backend does not support vectors
385 <li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
386 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
387 C++ code compiled with LLC or native compilers.</li>
393 <!-- ======================================================================= -->
394 <div class="doc_subsection">
395 <a name="c-fe">Known problems with the C front-end</a>
398 <!-- _______________________________________________________________________ -->
399 <div class="doc_subsubsection">Bugs</div>
401 <div class="doc_text">
403 <p>llvm-gcc4 does not currently support <a href="http://llvm.org/PR869">Link-Time
404 Optimization</a> on most platforms "out-of-the-box". Please inquire on the
405 llvmdev mailing list if you are interested.</p>
409 <!-- _______________________________________________________________________ -->
410 <div class="doc_subsubsection">
414 <div class="doc_text">
417 <li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
418 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
421 <li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
423 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
425 As in Algol and Pascal, lexical scoping of functions.
426 Nested functions are supported, but llvm-gcc does not support
427 taking the address of a nested function (except on the X86-32 target)
428 or non-local gotos.</li>
430 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
432 Declaring that functions have no side effects or that they can never
435 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
436 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
437 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
438 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
439 <tt>noreturn</tt>, <tt>pure</tt>, <tt>regparm</tt>
440 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
441 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
443 <b>Ignored:</b> <tt>nothrow</tt>, <tt>malloc</tt>,
444 <tt>no_instrument_function</tt></li>
448 <li><p>llvm-gcc supports the vast majority of GCC extensions, including:</p>
451 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas">Pragmas</a>: Pragmas accepted by GCC.</li>
452 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Local-Labels.html#Local%20Labels">Local Labels</a>: Labels local to a block.</li>
453 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#Other%20Builtins">Other Builtins</a>:
454 Other built-in functions.</li>
455 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html#Variable%20Attributes">Variable Attributes</a>:
456 Specifying attributes of variables.</li>
457 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type%20Attributes">Type Attributes</a>: Specifying attributes of types.</li>
458 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Thread_002dLocal.html">Thread-Local</a>: Per-thread variables.</li>
459 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html#Variable%20Length">Variable Length</a>:
460 Arrays whose length is computed at run time.</li>
461 <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>
462 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html#Statement%20Exprs">Statement Exprs</a>: Putting statements and declarations inside expressions.</li>
463 <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>
464 <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>
465 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals">Conditionals</a>: Omitting the middle operand of a <code>?:</code> expression.</li>
466 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Long-Long.html#Long%20Long">Long Long</a>: Double-word integers.</li>
467 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Complex.html#Complex">Complex</a>: Data types for complex numbers.</li>
468 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html#Hex%20Floats">Hex Floats</a>:Hexadecimal floating-point constants.</li>
469 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html#Zero%20Length">Zero Length</a>: Zero-length arrays.</li>
470 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html#Empty%20Structures">Empty Structures</a>: Structures with no members.</li>
471 <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>
472 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Escaped-Newlines.html#Escaped%20Newlines">Escaped Newlines</a>: Slightly looser rules for escaped newlines.</li>
473 <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>
474 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Constraints.html#Constraints">Constraints</a>: Constraints for asm operands.</li>
475 <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>
476 <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>
477 <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>
478 <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>
479 <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>
480 <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>
481 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Initializers.html#Initializers">Initializers</a>: Non-constant initializers.</li>
482 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Compound-Literals.html#Compound%20Literals">Compound Literals</a>: Compound literals give structures, unions,
483 or arrays as values.</li>
484 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html#Designated%20Inits">Designated Inits</a>: Labeling elements of initializers.</li>
485 <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>
486 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Case-Ranges.html#Case%20Ranges">Case Ranges</a>: `case 1 ... 9' and such.</li>
487 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Mixed-Declarations.html#Mixed%20Declarations">Mixed Declarations</a>: Mixing declarations and code.</li>
488 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Prototypes.html#Function%20Prototypes">Function Prototypes</a>: Prototype declarations and old-style definitions.</li>
489 <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>
490 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Dollar-Signs.html#Dollar%20Signs">Dollar Signs</a>: Dollar sign is allowed in identifiers.</li>
491 <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>
492 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Alignment.html#Alignment">Alignment</a>: Inquiring about the alignment of a type or variable.</li>
493 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Inline.html#Inline">Inline</a>: Defining inline functions (as fast as macros).</li>
494 <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>
495 <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>
496 <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>
497 <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>
498 <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>
499 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Attribute%20Syntax">Attribute Syntax</a>: Formal syntax for attributes.</li>
504 <p>If you run into GCC extensions which have not been included in any of these
505 lists, please let us know (also including whether or not they work).</p>
509 <!-- ======================================================================= -->
510 <div class="doc_subsection">
511 <a name="c++-fe">Known problems with the C++ front-end</a>
514 <div class="doc_text">
516 <p>The C++ front-end is considered to be fully
517 tested and works for a number of non-trivial programs, including LLVM
518 itself, Qt, Mozilla, etc.</p>
521 <li>Exception handling only works well on the X86 and PowerPC targets.</li>
528 <!-- *********************************************************************** -->
529 <div class="doc_section">
530 <a name="additionalinfo">Additional Information</a>
532 <!-- *********************************************************************** -->
534 <div class="doc_text">
536 <p>A wide variety of additional information is available on the <a
537 href="http://llvm.org">LLVM web page</a>, in particular in the <a
538 href="http://llvm.org/docs/">documentation</a> section. The web page also
539 contains versions of the API documentation which is up-to-date with the
540 Subversion version of the source code.
541 You can access versions of these documents specific to this release by going
542 into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
544 <p>If you have any questions or comments about LLVM, please feel free to contact
545 us via the <a href="http://llvm.org/docs/#maillist"> mailing
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