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7 <title>LLVM 2.7 Release Notes</title>
11 <div class="doc_title">LLVM 2.7 Release Notes</div>
13 <img align=right src="http://llvm.org/img/DragonSmall.png"
14 width="136" height="136">
17 <li><a href="#intro">Introduction</a></li>
18 <li><a href="#subproj">Sub-project Status Update</a></li>
19 <li><a href="#externalproj">External Projects Using LLVM 2.7</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 2.7?</a></li>
21 <li><a href="GettingStarted.html">Installation Instructions</a></li>
22 <li><a href="#portability">Portability and Supported Platforms</a></li>
23 <li><a href="#knownproblems">Known Problems</a></li>
24 <li><a href="#additionalinfo">Additional Information</a></li>
27 <div class="doc_author">
28 <p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
32 <h1 style="color:red">These are in-progress notes for the upcoming LLVM 2.7
35 <a href="http://llvm.org/releases/2.6/docs/ReleaseNotes.html">LLVM 2.6
36 Release Notes</a>.</h1>-->
38 <!-- *********************************************************************** -->
39 <div class="doc_section">
40 <a name="intro">Introduction</a>
42 <!-- *********************************************************************** -->
44 <div class="doc_text">
46 <p>This document contains the release notes for the LLVM Compiler
47 Infrastructure, release 2.7. Here we describe the status of LLVM, including
48 major improvements from the previous release and significant known problems.
49 All LLVM releases may be downloaded from the <a
50 href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
52 <p>For more information about LLVM, including information about the latest
53 release, please check out the <a href="http://llvm.org/">main LLVM
54 web site</a>. If you have questions or comments, the <a
55 href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's
56 Mailing List</a> is a good place to send them.</p>
58 <p>Note that if you are reading this file from a Subversion checkout or the
59 main LLVM web page, this document applies to the <i>next</i> release, not the
60 current one. To see the release notes for a specific release, please see the
61 <a href="http://llvm.org/releases/">releases page</a>.</p>
64 <p>FIXME: llvm.org moved to new server, mention new logo, Ted and Doug new code
65 owners, web page in llvm-www repos.</p>
72 include/llvm/Analysis/LiveValues.h => Dan
73 lib/Transforms/IPO/MergeFunctions.cpp => consider for 2.8.
74 llvm/Analysis/PointerTracking.h => Edwin wants this, consider for 2.8.
77 lib/Transforms/Utils/SSI.cpp -> ABCD depends on it.
81 <!-- Features that need text if they're finished for 2.7:
84 variable debug info for optimized code
85 postalloc scheduler: anti dependence breaking, hazard recognizer?
87 loop dependence analysis
88 ELF Writer? How stable?
89 <li>PostRA scheduler improvements, ARM adoption (David Goodwin).</li>
92 <!-- for announcement email:
96 KLEE web page at klee.llvm.org
97 Many new papers added to /pubs/
101 <!-- *********************************************************************** -->
102 <div class="doc_section">
103 <a name="subproj">Sub-project Status Update</a>
105 <!-- *********************************************************************** -->
107 <div class="doc_text">
109 The LLVM 2.7 distribution currently consists of code from the core LLVM
110 repository (which roughly includes the LLVM optimizers, code generators
111 and supporting tools), the Clang repository and the llvm-gcc repository. In
112 addition to this code, the LLVM Project includes other sub-projects that are in
113 development. Here we include updates on these subprojects.
119 <!--=========================================================================-->
120 <div class="doc_subsection">
121 <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
124 <div class="doc_text">
126 <p>The <a href="http://clang.llvm.org/">Clang project</a> is ...</p>
128 <p>In the LLVM 2.7 time-frame, the Clang team has made many improvements:</p>
131 <li>FIXME: C++! Include a link to cxx_compatibility.html</li>
133 <li>FIXME: Static Analyzer improvements?</li>
135 <li>CIndex API and Python bindings: Clang now includes a C API as part of the
136 CIndex library. Although we make make some changes to the API in the future, it
137 is intended to be stable and has been designed for use by external projects. See
139 doxygen <a href="http://clang.llvm.org/doxygen/group__CINDEX.html">CIndex</a>
140 documentation for more details. The CIndex API also includings an preliminary
141 set of Python bindings.</li>
143 <li>ARM Support: Clang now has ABI support for both the Darwin and Linux ARM
144 ABIs. Coupled with many improvements to the LLVM ARM backend, Clang is now
145 suitable for use as a a beta quality ARM compiler.</li>
149 <!--=========================================================================-->
150 <div class="doc_subsection">
151 <a name="clangsa">Clang Static Analyzer</a>
154 <div class="doc_text">
156 <p>Previously announced in the 2.4, 2.5, and 2.6 LLVM releases, the Clang project also
157 includes an early stage static source code analysis tool for <a
158 href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
159 in C and Objective-C programs. The tool performs checks to find
160 bugs that occur on a specific path within a program.</p>
162 <p>In the LLVM 2.7 time-frame, the analyzer core has sprouted legs and...</p>
166 <!--=========================================================================-->
167 <div class="doc_subsection">
168 <a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
171 <div class="doc_text">
173 The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
174 a JVM and a CLI Virtual Machine (Microsoft .NET is an
175 implementation of the CLI) using LLVM for static and just-in-time
179 With the release of LLVM 2.7, VMKit has shifted to a great framework for writing
180 virtual machines. VMKit now offers precise and efficient garbage collection with
181 multi-threading support, thanks to the MMTk memory management toolkit, as well
182 as just in time and ahead of time compilation with LLVM. The major changes in
187 <li>Garbage collection: VMKit now uses the MMTk toolkit for garbage collectors.
188 The first collector to be ported is the MarkSweep collector, which is precise,
189 and drastically improves the performance of VMKit.</li>
190 <li>Line number information in the JVM: by using the debug metadata of LLVM, the
191 JVM now supports precise line number information, useful when printing a stack
193 <li>Interface calls in the JVM: we implemented a variant of the Interface Method
194 Table technique for interface calls in the JVM.
201 <!--=========================================================================-->
202 <div class="doc_subsection">
203 <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
206 <div class="doc_text">
208 The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
209 is a simple library that provides an implementation of the low-level
210 target-specific hooks required by code generation and other runtime components.
211 For example, when compiling for a 32-bit target, converting a double to a 64-bit
212 unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
213 function. The compiler-rt library provides highly optimized implementations of
214 this and other low-level routines (some are 3x faster than the equivalent
215 libgcc routines).</p>
218 All of the code in the compiler-rt project is available under the standard LLVM
219 License, a "BSD-style" license.</p>
223 <!--=========================================================================-->
224 <div class="doc_subsection">
225 <a name="dragonegg">DragonEgg: llvm-gcc ported to gcc-4.5</a>
228 <div class="doc_text">
230 <a href="http://dragonegg.llvm.org/">DragonEgg</a> is a port of llvm-gcc to
231 gcc-4.5. Unlike llvm-gcc, which makes many intrusive changes to the underlying
232 gcc-4.2 code, dragonegg in theory does not require any gcc-4.5 modifications
233 whatsoever (currently one small patch is needed). This is thanks to the new
234 <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin architecture</a>, which
235 makes it possible to modify the behaviour of gcc at runtime by loading a plugin,
236 which is nothing more than a dynamic library which conforms to the gcc plugin
237 interface. DragonEgg is a gcc plugin that causes the LLVM optimizers to be run
238 instead of the gcc optimizers, and the LLVM code generators instead of the gcc
239 code generators, just like llvm-gcc. To use it, you add
240 "-fplugin=path/dragonegg.so" to the gcc-4.5 command line, and gcc-4.5 magically
241 becomes llvm-gcc-4.5!
245 DragonEgg is still a work in progress. Currently C works very well, while C++,
246 Ada and Fortran work fairly well. All other languages either don't work at all,
247 or only work poorly. For the moment only the x86-32 and x86-64 targets are
248 supported, and only on linux.
252 DragonEgg has not yet been released. Once gcc-4.5 has been released, dragonegg
253 will probably be released as part of the following LLVM release.
259 <!--=========================================================================-->
260 <div class="doc_subsection">
261 <a name="mc">llvm-mc: Machine Code Toolkit</a>
264 <div class="doc_text">
266 The LLVM Machine Code (MC) Toolkit project is ...
272 <!-- *********************************************************************** -->
273 <div class="doc_section">
274 <a name="externalproj">External Open Source Projects Using LLVM 2.7</a>
276 <!-- *********************************************************************** -->
278 <div class="doc_text">
280 <p>An exciting aspect of LLVM is that it is used as an enabling technology for
281 a lot of other language and tools projects. This section lists some of the
282 projects that have already been updated to work with LLVM 2.7.</p>
286 <!--=========================================================================-->
287 <div class="doc_subsection">
288 <a name="Rubinius">Rubinius</a>
291 <div class="doc_text">
294 <p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
295 for running Ruby code which strives to write as much of the core class
296 implementation in Ruby as possible. Combined with a bytecode interpreting VM, it
297 uses LLVM to optimize and compile ruby code down to machine code. Techniques
298 such as type feedback, method inlining, and uncommon traps are all used to
299 remove dynamism from ruby execution and increase performance.</p>
301 <p>Since LLVM 2.5, Rubinius has made several major leaps forward, implementing
302 a counter based JIT, type feedback and speculative method inlining.
308 <!--=========================================================================-->
309 <div class="doc_subsection">
310 <a name="macruby">MacRuby</a>
313 <div class="doc_text">
318 <a href="http://macruby.org">MacRuby</a> is an implementation of Ruby on top of
319 core Mac OS X technologies, such as the Objective-C common runtime and garbage
320 collector and the CoreFoundation framework. It is principally developed by
321 Apple and aims at enabling the creation of full-fledged Mac OS X applications.
325 MacRuby uses LLVM for optimization passes, JIT and AOT compilation of Ruby
326 expressions. It also uses zero-cost DWARF exceptions to implement Ruby exception
332 <!--=========================================================================-->
333 <div class="doc_subsection">
334 <a name="pure">Pure</a>
337 <div class="doc_text">
339 <a href="http://pure-lang.googlecode.com/">Pure</a>
340 is an algebraic/functional programming language based on term rewriting.
341 Programs are collections of equations which are used to evaluate expressions in
342 a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
343 lexical closures, a hygienic macro system (also based on term rewriting),
344 built-in list and matrix support (including list and matrix comprehensions) and
345 an easy-to-use C interface. The interpreter uses LLVM as a backend to
346 JIT-compile Pure programs to fast native code.</p>
348 <p>Pure versions 0.43 and later have been tested and are known to work with
349 LLVM 2.7 (and continue to work with older LLVM releases >= 2.5).</p>
354 <!--=========================================================================-->
355 <div class="doc_subsection">
356 <a name="ldc">LLVM D Compiler</a>
359 <div class="doc_text">
363 <a href="http://www.dsource.org/projects/ldc">LDC</a> is an implementation of
364 the D Programming Language using the LLVM optimizer and code generator.
365 The LDC project works great with the LLVM 2.6 release. General improvements in
367 cycle have included new inline asm constraint handling, better debug info
368 support, general bug fixes and better x86-64 support. This has allowed
369 some major improvements in LDC, getting it much closer to being as
370 fully featured as the original DMD compiler from DigitalMars.-->
374 <!--=========================================================================-->
375 <div class="doc_subsection">
376 <a name="RoadsendPHP">Roadsend PHP</a>
379 <div class="doc_text">
381 <a href="http://code.roadsend.com/rphp">Roadsend PHP</a> (rphp) is an open
382 source implementation of the PHP programming
383 language that uses LLVM for its optimizer, JIT and static compiler. This is a
384 reimplementation of an earlier project that is now based on LLVM.
388 <!--=========================================================================-->
389 <div class="doc_subsection">
390 <a name="UnladenSwallow">Unladen Swallow</a>
393 <div class="doc_text">
395 <a href="http://code.google.com/p/unladen-swallow/">Unladen Swallow</a> is a
396 branch of <a href="http://python.org/">Python</a> intended to be fully
397 compatible and significantly faster. It uses LLVM's optimization passes and JIT
402 <!--=========================================================================-->
403 <div class="doc_subsection">
404 <a name="llvm-lua">llvm-lua</a>
407 <div class="doc_text">
411 <a href="http://code.google.com/p/llvm-lua/">LLVM-Lua</a> uses LLVM to add JIT
412 and static compiling support to the Lua VM. Lua bytecode is analyzed to
413 remove type checks, then LLVM is used to compile the bytecode down to machine
418 <!--=========================================================================-->
419 <div class="doc_subsection">
420 <a name="icedtea">IcedTea Java Virtual Machine Implementation</a>
423 <div class="doc_text">
427 <a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
428 harness to build OpenJDK using only free software build tools and to provide
429 replacements for the not-yet free parts of OpenJDK. One of the extensions that
430 IcedTea provides is a new JIT compiler named <a
431 href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
432 to provide native code generation without introducing processor-dependent
438 <!--=========================================================================-->
439 <div class="doc_subsection">
440 <a name="tce">TTA-based Codesign Environment (TCE)</a>
443 <div class="doc_text">
445 <a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
446 application-specific processors (ASP) based on the Transport triggered
447 architecture (TTA). The toolset provides a complete co-design flow from C/C++
448 programs down to synthesizable VHDL and parallel program binaries. Processor
449 customization points include the register files, function units, supported
450 operations, and the interconnection network.</p>
452 <p>TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
453 independent optimizations and also for parts of code generation. It generates
454 new LLVM-based code generators "on the fly" for the designed TTA processors and
455 loads them in to the compiler backend as runtime libraries to avoid per-target
456 recompilation of larger parts of the compiler chain.</p>
460 <!--=========================================================================-->
461 <div class="doc_subsection">
462 <a name="safecode">SAFECode Compiler</a>
465 <div class="doc_text">
467 <a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C
468 compiler built using LLVM. It takes standard, unannotated C code, analyzes the
469 code to ensure that memory accesses and array indexing operations are safe, and
470 instruments the code with run-time checks when safety cannot be proven
476 <!-- *********************************************************************** -->
477 <div class="doc_section">
478 <a name="whatsnew">What's New in LLVM 2.7?</a>
480 <!-- *********************************************************************** -->
482 <div class="doc_text">
484 <p>This release includes a huge number of bug fixes, performance tweaks and
485 minor improvements. Some of the major improvements and new features are listed
491 <!--=========================================================================-->
492 <div class="doc_subsection">
493 <a name="majorfeatures">Major New Features</a>
496 <div class="doc_text">
498 <p>LLVM 2.7 includes several major new capabilities:</p>
504 Extensible metadata solid.
506 Debug info improvements: using metadata instead of llvm.dbg global variables.
507 This brings several enhancements including improved compile times.
509 New instruction selector.
510 GHC Haskell ABI/ calling conv support.
511 Pre-Alpha support for unions in IR.
512 New InlineHint and StackAlignment function attributes
513 Code generator MC'ized except for debug info and EH.
514 New SCEV AA pass: -scev-aa
515 Inliner reuses arrays allocas when inlining multiple callers to reduce stack usage.
516 MC encoding and disassembler apis.
517 Optimal Edge Profiling?
518 Instcombine is now a library, has its own IRBuilder to simplify itself.
519 New llvm/Support/Regex.h API. FileCheck now does regex's
520 Many subtle pointer invalidation bugs in Callgraph have been fixed and it now uses asserting value handles.
521 MC Disassembler (with blog post), MCInstPrinter. Many X86 backend and AsmPrinter simplifications
522 Various tools like llc and opt now read either .ll or .bc files as input.
523 Malloc and free instructions got removed, along with LowerAllocations pass.
524 compiler-rt support for ARM.
525 completely llvm-gcc NEON support.
526 Can transcode from GAS to intel syntax with "llvm-mc foo.s -output-asm-variant=1"
527 JIT debug information with GDB 7.0
528 New CodeGen Level CSE
529 CMake can now run tests, what other improvements?
530 ARM/Thumb using reg scavenging for stack object address materialization (PEI).
531 New SSAUpdater and MachineSSAUpdater classes for unstructured ssa updating,
532 changed jump threading, GVN, etc to use it which simplified them and speed
534 Combiner-AA improvements, why not on by default?
535 Pre-regalloc tail duplication
536 x86 sibcall / tailcall optimization in CCC mode.
537 New LSR with "full strength reduction" mode. Description?
538 Codegen level OptimizeExtsPass pass, takes advantage of x86 subregs.
539 Better code size analysis in loop unswitch, inliner code split out to a new
540 CodeMetrics class for reuse.
541 The ARM backend now has good support for ARMv4 backend (tested on StrongARM
542 hardware), previously only supported ARMv4T and newer.
543 Half-float support in APFloat
544 Indirect branch + address of label (blog post), particularly useful for interpreters.
545 Many changes to the pass ordering for improved optimization effectiveness.
546 BasicAA improved to be less dependent on "type safe" pointers, it can now look
547 through bitcasts more aggressively.
548 GVN PHI Translation improvements. blog post: http://blog.llvm.org/2009/12/advanced-topics-in-redundant-load.html
551 PostRA scheduler for X86?
552 llvm.dbg.value, not being used by default though, more in 2.8. Many improvements to debug info
553 Support for the GCC option -fno-schedule-insns
554 non-temporal load/store
555 libllvm2.7.so?? configure with --enable-shared
556 dbgs() and -debug-buffer-size=N
557 New MicroBlaze backend. http://en.wikipedia.org/wiki/MicroBlaze
558 XMM subreg modeling for extraction of the low element.
561 Opt now works conservatively if no target data is set (is this fully working?)
562 Target data now has notion of 'native' integer data types which optimizations can use.
563 ARM backend generates instructions in unified assembly syntax.
564 New Analysis/InstructionSimplify.h interface for simplifying instructions that don't exist.
565 Jump threading is now much more aggressive at simplifying correlated
566 conditionals and threading blocks with otherwise complex logic. CondProp pass
567 removed (functionality merged into jump threading).
568 X86 and XCore supports returning arbitrary return values, returning too many values is
569 supported by returning through a hidden pointer.
570 verbose-asm now produces information about spill slots and loop nests
573 Defaults to RTTI off (smaller code size!), packagers should build with make REQUIRE_RTTI=1.
575 PredSimplify, LoopVR, GVNPRE, RSProfiling (random sampling profiling) got removed.
576 LLVM command line tools now overwrite their output, before they would only do this with -f.
577 DOUT removed, use DEBUG(errs() instead.
578 Much stuff converted to use raw_ostream instead of std::ostream.
579 TargetAsmInfo renamed to MCAsmInfo
580 llvm/ADT/iterator.h gone.
585 <!--=========================================================================-->
586 <div class="doc_subsection">
587 <a name="coreimprovements">LLVM IR and Core Improvements</a>
590 <div class="doc_text">
591 <p>LLVM IR has several new features for better support of new targets and that
592 expose new optimization opportunities:</p>
600 <!--=========================================================================-->
601 <div class="doc_subsection">
602 <a name="optimizer">Optimizer Improvements</a>
605 <div class="doc_text">
607 <p>In addition to a large array of minor performance tweaks and bug fixes, this
608 release includes a few major enhancements and additions to the optimizers:</p>
616 <p>Also, -anders-aa was removed</p>
621 <!--=========================================================================-->
622 <div class="doc_subsection">
623 <a name="executionengine">Interpreter and JIT Improvements</a>
626 <div class="doc_text">
630 href="http://llvm.org/viewvc/llvm-project?view=rev&revision=85295">defaults
631 to compiling eagerly</a> to avoid a race condition in the lazy JIT.
632 Clients that still want the lazy JIT can switch it on by calling
633 <tt>ExecutionEngine::DisableLazyCompilation(false)</tt>.</li>
634 <li>It is now possible to create more than one JIT instance in the same process.
635 These JITs can generate machine code in parallel,
636 although <a href="http://llvm.org/docs/ProgrammersManual.html#jitthreading">you
637 still have to obey the other threading restrictions</a>.</li>
642 <!--=========================================================================-->
643 <div class="doc_subsection">
644 <a name="codegen">Target Independent Code Generator Improvements</a>
647 <div class="doc_text">
649 <p>We have put a significant amount of work into the code generator
650 infrastructure, which allows us to implement more aggressive algorithms and make
659 <!--=========================================================================-->
660 <div class="doc_subsection">
661 <a name="x86">X86-32 and X86-64 Target Improvements</a>
664 <div class="doc_text">
665 <p>New features of the X86 target include:
676 <!--=========================================================================-->
677 <div class="doc_subsection">
678 <a name="pic16">PIC16 Target Improvements</a>
681 <div class="doc_text">
682 <p>New features of the PIC16 target include:
689 <p>Things not yet supported:</p>
692 <li>Variable arguments.</li>
693 <li>Interrupts/programs.</li>
698 <!--=========================================================================-->
699 <div class="doc_subsection">
700 <a name="ARM">ARM Target Improvements</a>
703 <div class="doc_text">
704 <p>New features of the ARM target include:
715 <!--=========================================================================-->
716 <div class="doc_subsection">
717 <a name="OtherTarget">Other Target Specific Improvements</a>
720 <div class="doc_text">
721 <p>New features of other targets include:
730 <!--=========================================================================-->
731 <div class="doc_subsection">
732 <a name="newapis">New Useful APIs</a>
735 <div class="doc_text">
737 <p>This release includes a number of new APIs that are used internally, which
738 may also be useful for external clients.
748 <!--=========================================================================-->
749 <div class="doc_subsection">
750 <a name="otherimprovements">Other Improvements and New Features</a>
753 <div class="doc_text">
754 <p>Other miscellaneous features include:</p>
763 <!--=========================================================================-->
764 <div class="doc_subsection">
765 <a name="changes">Major Changes and Removed Features</a>
768 <div class="doc_text">
770 <p>If you're already an LLVM user or developer with out-of-tree changes based
771 on LLVM 2.6, this section lists some "gotchas" that you may run into upgrading
772 from the previous release.</p>
775 <li>The LLVM interpreter now defaults to <em>not</em> using <tt>libffi</tt> even
776 if you have it installed. This makes it more likely that an LLVM built on one
777 system will work when copied to a similar system. To use <tt>libffi</tt>,
778 configure with <tt>--enable-libffi</tt>.
783 <p>In addition, many APIs have changed in this release. Some of the major LLVM
787 <li><tt>ModuleProvider</tt> has been <a
788 href="http://llvm.org/viewvc/llvm-project?view=rev&revision=94686">removed</a>
789 and its methods moved to <tt>Module</tt> and <tt>GlobalValue</tt>.
790 Most clients can remove uses of <tt>ExistingModuleProvider</tt>,
791 replace <tt>getBitcodeModuleProvider</tt> with
792 <tt>getLazyBitcodeModule</tt>, and pass their <tt>Module</tt> to
793 functions that used to accept <tt>ModuleProvider</tt>. Clients who
794 wrote their own <tt>ModuleProvider</tt>s will need to derive from
795 <tt>GVMaterializer</tt> instead and use
796 <tt>Module::setMaterializer</tt> to attach it to a
797 <tt>Module</tt>.</li>
799 <li><tt>GhostLinkage</tt> has given up the ghost.
800 <tt>GlobalValue</tt>s that have not yet been read from their backing
801 storage have the same linkage they will have after being read in.
802 Clients must replace calls to
803 <tt>GlobalValue::hasNotBeenReadFromBitcode</tt> with
804 <tt>GlobalValue::isMaterializable</tt>.</li>
806 <li>FIXME: Debug info has been totally redone. Add pointers to new APIs. Substantial caveats about compatibility of .ll and .bc files.</li>
808 <li>The <tt>llvm/Support/DataTypes.h</tt> header has moved
809 to <tt>llvm/System/DataTypes.h</tt>.</li>
811 <li>The <tt>isInteger</tt>, <tt>isIntOrIntVector</tt>, <tt>isFloatingPoint</tt>,
812 <tt>isFPOrFPVector</tt> and <tt>isFPOrFPVector</tt> methods have been renamed
813 <tt>isIntegerTy</tt>, <tt>isIntOrIntVectorTy</tt>, <tt>isFloatingPointTy</tt>,
814 <tt>isFPOrFPVectorTy</tt> and <tt>isFPOrFPVectorTy</tt> respectively.</li>
821 <!-- *********************************************************************** -->
822 <div class="doc_section">
823 <a name="portability">Portability and Supported Platforms</a>
825 <!-- *********************************************************************** -->
827 <div class="doc_text">
829 <p>LLVM is known to work on the following platforms:</p>
832 <li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
833 Linux, Fedora Core, FreeBSD and AuroraUX (and probably other unix-like
835 <li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
836 and 64-bit modes.</li>
837 <li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
838 <li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
839 support is available for native builds with Visual C++).</li>
840 <li>Sun x86 and AMD64 machines running Solaris 10, OpenSolaris 0906.</li>
841 <li>Alpha-based machines running Debian GNU/Linux.</li>
844 <p>The core LLVM infrastructure uses GNU autoconf to adapt itself
845 to the machine and operating system on which it is built. However, minor
846 porting may be required to get LLVM to work on new platforms. We welcome your
847 portability patches and reports of successful builds or error messages.</p>
851 <!-- *********************************************************************** -->
852 <div class="doc_section">
853 <a name="knownproblems">Known Problems</a>
855 <!-- *********************************************************************** -->
857 <div class="doc_text">
859 <p>This section contains significant known problems with the LLVM system,
860 listed by component. If you run into a problem, please check the <a
861 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
862 there isn't already one.</p>
865 <li>LLVM will not correctly compile on Solaris and/or OpenSolaris
866 using the stock GCC 3.x.x series 'out the box',
867 See: <a href="GettingStarted.html#brokengcc">Broken versions of GCC and other tools</a>.
868 However, A <a href="http://pkg.auroraux.org/GCC">Modern GCC Build</a>
869 for x86/x86-64 has been made available from the third party AuroraUX Project
870 that has been meticulously tested for bootstrapping LLVM & Clang.</li>
875 <!-- ======================================================================= -->
876 <div class="doc_subsection">
877 <a name="experimental">Experimental features included with this release</a>
880 <div class="doc_text">
882 <p>The following components of this LLVM release are either untested, known to
883 be broken or unreliable, or are in early development. These components should
884 not be relied on, and bugs should not be filed against them, but they may be
885 useful to some people. In particular, if you would like to work on one of these
886 components, please contact us on the <a
887 href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
890 <li>The MSIL, Alpha, SPU, MIPS, PIC16, Blackfin, MSP430, SystemZ and MicroBlaze
891 backends are experimental.</li>
892 <li>The <tt>llc</tt> "<tt>-filetype=asm</tt>" (the default) is the only
893 supported value for this option. The MachO writer is experimental, and
894 works much better in mainline SVN.</li>
899 <!-- ======================================================================= -->
900 <div class="doc_subsection">
901 <a name="x86-be">Known problems with the X86 back-end</a>
904 <div class="doc_text">
907 <li>The X86 backend does not yet support
908 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
909 floating point stack</a>. It supports the 'f' and 't' constraints, but not
911 <li>The X86 backend generates inefficient floating point code when configured
912 to generate code for systems that don't have SSE2.</li>
913 <li>Win64 code generation wasn't widely tested. Everything should work, but we
914 expect small issues to happen. Also, llvm-gcc cannot build the mingw64
915 runtime currently due
916 to <a href="http://llvm.org/PR2255">several</a>
917 <a href="http://llvm.org/PR2257">bugs</a> and due to lack of support for
919 'u' inline assembly constraint and for X87 floating point inline assembly.</li>
920 <li>The X86-64 backend does not yet support the LLVM IR instruction
921 <tt>va_arg</tt>. Currently, the llvm-gcc and front-ends support variadic
922 argument constructs on X86-64 by lowering them manually.</li>
927 <!-- ======================================================================= -->
928 <div class="doc_subsection">
929 <a name="ppc-be">Known problems with the PowerPC back-end</a>
932 <div class="doc_text">
935 <li>The Linux PPC32/ABI support needs testing for the interpreter and static
936 compilation, and lacks support for debug information.</li>
941 <!-- ======================================================================= -->
942 <div class="doc_subsection">
943 <a name="arm-be">Known problems with the ARM back-end</a>
946 <div class="doc_text">
949 <li>Support for the Advanced SIMD (Neon) instruction set is still incomplete
950 and not well tested. Some features may not work at all, and the code quality
951 may be poor in some cases.</li>
952 <li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
953 processors, thumb programs can crash or produce wrong
954 results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
955 <li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
961 <!-- ======================================================================= -->
962 <div class="doc_subsection">
963 <a name="sparc-be">Known problems with the SPARC back-end</a>
966 <div class="doc_text">
969 <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
970 support the 64-bit SPARC ABI (-m64).</li>
975 <!-- ======================================================================= -->
976 <div class="doc_subsection">
977 <a name="mips-be">Known problems with the MIPS back-end</a>
980 <div class="doc_text">
983 <li>64-bit MIPS targets are not supported yet.</li>
988 <!-- ======================================================================= -->
989 <div class="doc_subsection">
990 <a name="alpha-be">Known problems with the Alpha back-end</a>
993 <div class="doc_text">
997 <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
998 appropriate nops inserted to ensure restartability.</li>
1003 <!-- ======================================================================= -->
1004 <div class="doc_subsection">
1005 <a name="c-be">Known problems with the C back-end</a>
1008 <div class="doc_text">
1011 <li><a href="http://llvm.org/PR802">The C backend has only basic support for
1012 inline assembly code</a>.</li>
1013 <li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1014 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1015 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1016 <li>The C backend does not support all exception handling constructs.</li>
1017 <li>The C backend does not support arbitrary precision integers.</li>
1023 <!-- ======================================================================= -->
1024 <div class="doc_subsection">
1025 <a name="c-fe">Known problems with the llvm-gcc C and C++ front-end</a>
1028 <div class="doc_text">
1030 <p>The only major language feature of GCC not supported by llvm-gcc is
1031 the <tt>__builtin_apply</tt> family of builtins. However, some extensions
1032 are only supported on some targets. For example, trampolines are only
1033 supported on some targets (these are used when you take the address of a
1034 nested function).</p>
1036 <p>If you run into GCC extensions which are not supported, please let us know.
1041 <!-- ======================================================================= -->
1042 <div class="doc_subsection">
1043 <a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
1046 <div class="doc_text">
1048 <li>Fortran support generally works, but there are still several unresolved bugs
1049 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1050 tools/gfortran component for details.</li>
1054 <!-- ======================================================================= -->
1055 <div class="doc_subsection">
1056 <a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
1059 <div class="doc_text">
1060 The llvm-gcc 4.2 Ada compiler works fairly well; however, this is not a mature
1061 technology, and problems should be expected.
1063 <li>The Ada front-end currently only builds on X86-32. This is mainly due
1064 to lack of trampoline support (pointers to nested functions) on other platforms.
1065 However, it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
1066 which does support trampolines.</li>
1067 <li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
1068 This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
1069 exception handling, which is used internally by the compiler.
1070 Workaround: configure with <tt>--disable-bootstrap</tt>.</li>
1071 <li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
1072 and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
1073 (c380004 also fails with gcc-4.2 mainline).
1074 If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
1075 causes the compiler to go into an infinite loop, using up all system memory.</li>
1076 <li>Some GCC specific Ada tests continue to crash the compiler.</li>
1077 <li>The <tt>-E</tt> binder option (exception backtraces)
1078 <a href="http://llvm.org/PR1982">does not work</a> and will result in programs
1079 crashing if an exception is raised. Workaround: do not use <tt>-E</tt>.</li>
1080 <li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
1081 or finish at a non-byte offset</a> in a record. Workaround: do not pack records
1082 or use representation clauses that result in a field of a non-discrete type
1083 starting or finishing in the middle of a byte.</li>
1084 <li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
1085 'main' as generated by the Ada binder to be invalid</a>.
1086 Workaround: hand edit the file to use pointers for <tt>argv</tt> and
1087 <tt>envp</tt> rather than integers.</li>
1088 <li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
1093 <!-- *********************************************************************** -->
1094 <div class="doc_section">
1095 <a name="additionalinfo">Additional Information</a>
1097 <!-- *********************************************************************** -->
1099 <div class="doc_text">
1101 <p>A wide variety of additional information is available on the <a
1102 href="http://llvm.org">LLVM web page</a>, in particular in the <a
1103 href="http://llvm.org/docs/">documentation</a> section. The web page also
1104 contains versions of the API documentation which is up-to-date with the
1105 Subversion version of the source code.
1106 You can access versions of these documents specific to this release by going
1107 into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1109 <p>If you have any questions or comments about LLVM, please feel free to contact
1110 us via the <a href="http://llvm.org/docs/#maillist"> mailing
1115 <!-- *********************************************************************** -->
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