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7 <title>LLVM 2.3 Release Notes</title>
11 <div class="doc_title">LLVM 2.3 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 <h1><font color="red">THIS IS A WORK IN PROGRESS FOR LLVM 2.3 (currently in
27 progress on SVN HEAD)</font></h1>
29 <!-- *********************************************************************** -->
30 <div class="doc_section">
31 <a name="intro">Introduction</a>
33 <!-- *********************************************************************** -->
35 <div class="doc_text">
37 <p>This document contains the release notes for the LLVM compiler
38 infrastructure, release 2.3. Here we describe the status of LLVM, including
39 major improvements from the previous release and any known problems. All LLVM
40 releases may be downloaded from the <a href="http://llvm.org/releases/">LLVM
41 releases web site</a>.</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 a Subversion checkout or the
50 main LLVM web page, this document applies to the <i>next</i> release, not the
51 current one. To see the release notes for a specific releases, please see the
52 <a 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 fourteenth public release of the LLVM Compiler Infrastructure.
65 It includes many features and refinements from LLVM 2.2.</p>
69 <!-- Unfinished features in 2.3:
70 Index Set Splitting not enabled by default
76 <!--=========================================================================-->
77 <div class="doc_subsection">
78 <a name="deprecation">Removed features in LLVM 2.3</a>
81 <div class="doc_text">
83 <p>LLVM 2.2 was the last LLVM release to support llvm-gcc 4.0 and llvm-upgrade.
84 llvm-gcc 4.0 has been replaced with llvm-gcc 4.2. llvm-upgrade was useful for
85 upgrading llvm 1.9 files to llvm 2.x syntax, but you can always use a previous
86 llvm release to do this.</p>
90 <!--=========================================================================-->
91 <div class="doc_subsection">
92 <a name="frontends">llvm-gcc 4.2 and clang</a>
95 <div class="doc_text">
97 <p>LLVM 2.3 fully supports llvm-gcc 4.2 front-end. </p>
99 <p>The <a href="http://clang.llvm.org/">clang project</a> is an effort to build
100 a set of new 'llvm native' front-end technologies for the LLVM optimizer
101 and code generator. Currently, its C and Objective-C support is maturing
102 nicely, and it has advanced source-to-source analysis and transformation
103 capabilities. If you are interested in building source-level tools for C and
104 Objective-C (and eventually C++), you should take a look. However, note that
105 clang is not an official part of the LLVM 2.3 release. If you are interested in
106 this project, please see its <a href="http://clang.llvm.org/">web site</a>.</p>
110 <!--=========================================================================-->
111 <div class="doc_subsection">
112 <a name="majorfeatures">Major New Features</a>
115 <div class="doc_text">
117 <p>LLVM 2.3 includes several major new capabilities:</p>
124 <!--=========================================================================-->
125 <div class="doc_subsection">
126 <a name="coreimprovements">LLVM Core Improvements</a>
129 <div class="doc_text">
130 <p>New features include:
139 <!--=========================================================================-->
140 <div class="doc_subsection">
141 <a name="codegen">Code Generator Improvements</a>
144 <div class="doc_text">
146 <p>We put a significant amount of work into the code generator infrastructure,
147 which allows us to implement more aggressive algorithms and make it run
151 <li>MemOperand in the code generator.</li>
156 <!--=========================================================================-->
157 <div class="doc_subsection">
158 <a name="optimizer">Optimizer Improvements</a>
161 <div class="doc_text">
163 <p>In addition to a huge array of bug fixes and minor performance tweaks, the
164 LLVM 2.3 optimizers support a few major enhancements:</p>
168 <li>Index set splitting on by default.</li>
175 <!--=========================================================================-->
176 <div class="doc_subsection">
177 <a name="targetspecific">Target Specific Improvements</a>
180 <div class="doc_text">
181 <p>New target-specific features include:
189 <!--=========================================================================-->
190 <div class="doc_subsection">
191 <a name="otherimprovements">Other Improvements</a>
194 <div class="doc_text">
195 <p>New features include:
203 <!-- *********************************************************************** -->
204 <div class="doc_section">
205 <a name="portability">Portability and Supported Platforms</a>
207 <!-- *********************************************************************** -->
209 <div class="doc_text">
211 <p>LLVM is known to work on the following platforms:</p>
214 <li>Intel and AMD machines running Red Hat Linux, Fedora Core and FreeBSD
215 (and probably other unix-like systems).</li>
216 <li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit and
218 <li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
219 <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
220 support is available for native builds with Visual C++).</li>
221 <li>Sun UltraSPARC workstations running Solaris 8.</li>
222 <li>Alpha-based machines running Debian GNU/Linux.</li>
223 <li>Itanium-based machines running Linux and HP-UX.</li>
226 <p>The core LLVM infrastructure uses
227 <a href="http://www.gnu.org/software/autoconf/">GNU autoconf</a> to adapt itself
228 to the machine and operating system on which it is built. However, minor
229 porting may be required to get LLVM to work on new platforms. We welcome your
230 portability patches and reports of successful builds or error messages.</p>
234 <!-- *********************************************************************** -->
235 <div class="doc_section">
236 <a name="knownproblems">Known Problems</a>
238 <!-- *********************************************************************** -->
240 <div class="doc_text">
242 <p>This section contains all known problems with the LLVM system, listed by
243 component. As new problems are discovered, they will be added to these
244 sections. If you run into a problem, please check the <a
245 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
246 there isn't already one.</p>
250 <!-- ======================================================================= -->
251 <div class="doc_subsection">
252 <a name="experimental">Experimental features included with this release</a>
255 <div class="doc_text">
257 <p>The following components of this LLVM release are either untested, known to
258 be broken or unreliable, or are in early development. These components should
259 not be relied on, and bugs should not be filed against them, but they may be
260 useful to some people. In particular, if you would like to work on one of these
261 components, please contact us on the <a
262 href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
265 <li>The MSIL, IA64, Alpha, SPU, and MIPS backends are experimental.</li>
266 <li>The LLC "<tt>-filetype=asm</tt>" (the default) is the only supported
267 value for this option.</li>
268 <li>The llvmc tool is not supported.</li>
273 <!-- ======================================================================= -->
274 <div class="doc_subsection">
275 <a name="x86-be">Known problems with the X86 back-end</a>
278 <div class="doc_text">
281 <li>The X86 backend does not yet support <a href="http://llvm.org/PR879">inline
282 assembly that uses the X86 floating point stack</a>.</li>
283 <li>The X86 backend occasionally has <a href="http://llvm.org/PR1649">alignment
284 problems</a> on operating systems that don't require 16-byte stack alignment
285 (including most non-darwin OS's like linux).</li>
286 <li>The X86 backend generates inefficient floating point code when configured to
287 generate code for systems that don't have SSE2.</li>
292 <!-- ======================================================================= -->
293 <div class="doc_subsection">
294 <a name="ppc-be">Known problems with the PowerPC back-end</a>
297 <div class="doc_text">
300 <li>The Linux PPC32/ABI support needs testing for the interpreter and static
301 compilation, and lacks support for debug information.</li>
306 <!-- ======================================================================= -->
307 <div class="doc_subsection">
308 <a name="arm-be">Known problems with the ARM back-end</a>
311 <div class="doc_text">
314 <li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
315 processors, thumb programs can crash or produce wrong
316 results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
317 <li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
319 <li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly execute
320 programs compiled with LLVM. Please use more recent versions of QEMU.</li>
325 <!-- ======================================================================= -->
326 <div class="doc_subsection">
327 <a name="sparc-be">Known problems with the SPARC back-end</a>
330 <div class="doc_text">
333 <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
334 support the 64-bit SPARC ABI (-m64).</li>
339 <!-- ======================================================================= -->
340 <div class="doc_subsection">
341 <a name="alpha-be">Known problems with the Alpha back-end</a>
344 <div class="doc_text">
348 <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
349 appropriate nops inserted to ensure restartability.</li>
354 <!-- ======================================================================= -->
355 <div class="doc_subsection">
356 <a name="ia64-be">Known problems with the IA64 back-end</a>
359 <div class="doc_text">
363 <li>C++ programs are likely to fail on IA64, as calls to <tt>setjmp</tt> are
364 made where the argument is not 16-byte aligned, as required on IA64. (Strictly
365 speaking this is not a bug in the IA64 back-end; it will also be encountered
366 when building C++ programs using the C back-end.)</li>
368 <li>The C++ front-end does not use <a href="http://llvm.org/PR406">IA64
369 ABI compliant layout of v-tables</a>. In particular, it just stores function
370 pointers instead of function descriptors in the vtable. This bug prevents
371 mixing C++ code compiled with LLVM with C++ objects compiled by other C++
374 <li>There are a few ABI violations which will lead to problems when mixing LLVM
375 output with code built with other compilers, particularly for floating-point
378 <li>Defining vararg functions is not supported (but calling them is ok).</li>
380 <li>The Itanium backend has bitrotted somewhat.</li>
385 <!-- ======================================================================= -->
386 <div class="doc_subsection">
387 <a name="c-be">Known problems with the C back-end</a>
390 <div class="doc_text">
393 <li><a href="http://llvm.org/PR802">The C backend does not support inline
394 assembly code</a>.</li>
395 <li><a href="http://llvm.org/PR1126">The C backend does not support vectors
397 <li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
398 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
399 C++ code compiled with LLC or native compilers.</li>
400 <li>The C backend does not support all exception handling constructs.</li>
406 <!-- ======================================================================= -->
407 <div class="doc_subsection">
408 <a name="c-fe">Known problems with the C front-end</a>
411 <!-- _______________________________________________________________________ -->
412 <div class="doc_subsubsection">Bugs</div>
414 <div class="doc_text">
416 <p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
417 Optimization</a> on most platforms "out-of-the-box". Please inquire on the
418 llvmdev mailing list if you are interested.</p>
422 <!-- _______________________________________________________________________ -->
423 <div class="doc_subsubsection">
427 <div class="doc_text">
430 <li><p>llvm-gcc does <b>not</b> support <tt>__builtin_apply</tt> yet.
431 See <a href="http://gcc.gnu.org/onlinedocs/gcc/Constructing-Calls.html#Constructing%20Calls">Constructing Calls</a>: Dispatching a call to another function.</p>
434 <li><p>llvm-gcc <b>partially</b> supports these GCC extensions:</p>
436 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html#Nested%20Functions">Nested Functions</a>:
438 As in Algol and Pascal, lexical scoping of functions.
439 Nested functions are supported, but llvm-gcc does not support
440 taking the address of a nested function (except on X86 targets)
441 or non-local gotos.</li>
443 <li><a href="http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function%20Attributes">Function Attributes</a>:
445 Declaring that functions have no side effects or that they can never
448 <b>Supported:</b> <tt>alias</tt>, <tt>always_inline</tt>, <tt>cdecl</tt>,
449 <tt>const</tt>, <tt>constructor</tt>, <tt>destructor</tt>,
450 <tt>deprecated</tt>, <tt>fastcall</tt>, <tt>format</tt>,
451 <tt>format_arg</tt>, <tt>non_null</tt>, <tt>noinline</tt>,
452 <tt>noreturn</tt>, <tt>nothrow</tt>, <tt>pure</tt>, <tt>regparm</tt>
453 <tt>section</tt>, <tt>stdcall</tt>, <tt>unused</tt>, <tt>used</tt>,
454 <tt>visibility</tt>, <tt>warn_unused_result</tt>, <tt>weak</tt><br>
456 <b>Ignored:</b> <tt>malloc</tt>,
457 <tt>no_instrument_function</tt></li>
463 <p>If you run into GCC extensions which have not been included in any of these
464 lists, please let us know (also including whether or not they work).</p>
468 <!-- ======================================================================= -->
469 <div class="doc_subsection">
470 <a name="c++-fe">Known problems with the C++ front-end</a>
473 <div class="doc_text">
475 <p>The C++ front-end is considered to be fully
476 tested and works for a number of non-trivial programs, including LLVM
477 itself, Qt, Mozilla, etc.</p>
480 <li>Exception handling only works well on the X86 and PowerPC targets.
481 It works well for x86-64 darwin but not x86-64 linux.</li>
487 <!-- ======================================================================= -->
488 <div class="doc_subsection">
489 <a name="ada-fe">Known problems with the Ada front-end</a>
492 <div class="doc_text">
493 The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
494 technology and problems should be expected.
496 <li>The Ada front-end currently only builds on x86-32. This is mainly due
497 to lack of trampoline support (pointers to nested functions) on other platforms,
498 however it <a href="http://llvm.org/PR2006">also fails to build on x86-64</a>
499 which does support trampolines.</li>
500 <li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
501 Workaround: configure with --disable-bootstrap.</li>
502 <li>The c380004 and <a href="http://llvm.org/PR2010">c393010</a> ACATS tests
503 fail (c380004 also fails with gcc-4.2 mainline).</li>
504 <li>Many gcc specific Ada tests continue to crash the compiler.</li>
505 <li>The -E binder option (exception backtraces)
506 <a href="http://llvm.org/PR1982">does not work</a> and will result in programs
507 crashing if an exception is raised. Workaround: do not use -E.</li>
508 <li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
509 or finish at a non-byte offset</a> in a record. Workaround: do not pack records
510 or use representation clauses that result in a field of a non-discrete type
511 starting or finishing in the middle of a byte.</li>
512 <li>The lli interpreter <a href="http://llvm.org/PR2009">considers 'main'
513 as generated by the Ada binder to be invalid</a>.
514 Workaround: hand edit the file to use pointers for argv and envp rather than
516 <li>The -fstack-check option <a href="http://llvm.org/PR2008">is ignored</a>.</li>
520 <!-- ======================================================================= -->
521 <div class="doc_subsection">
522 <a name="fortran-fe">Known problems with the Fortran front-end</a>
525 <div class="doc_text">
528 <li>The llvm-gcc 4.2 gfortran front-end supports a broad range of Fortran code, but does
529 <a href="http://llvm.org/PR1971">not support EQUIVALENCE yet</a>.</li>
535 <!-- *********************************************************************** -->
536 <div class="doc_section">
537 <a name="additionalinfo">Additional Information</a>
539 <!-- *********************************************************************** -->
541 <div class="doc_text">
543 <p>A wide variety of additional information is available on the <a
544 href="http://llvm.org">LLVM web page</a>, in particular in the <a
545 href="http://llvm.org/docs/">documentation</a> section. The web page also
546 contains versions of the API documentation which is up-to-date with the
547 Subversion version of the source code.
548 You can access versions of these documents specific to this release by going
549 into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
551 <p>If you have any questions or comments about LLVM, please feel free to contact
552 us via the <a href="http://llvm.org/docs/#maillist"> mailing
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