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11 <h1>LLVM 3.1 Release Notes</h1>
14 <img style="float:right" src="http://llvm.org/img/DragonSmall.png"
15 width="136" height="136" alt="LLVM Dragon Logo">
19 <li><a href="#intro">Introduction</a></li>
20 <li><a href="#subproj">Sub-project Status Update</a></li>
21 <li><a href="#externalproj">External Projects Using LLVM 3.1</a></li>
22 <li><a href="#whatsnew">What's New in LLVM?</a></li>
23 <li><a href="GettingStarted.html">Installation Instructions</a></li>
24 <li><a href="#knownproblems">Known Problems</a></li>
25 <li><a href="#additionalinfo">Additional Information</a></li>
28 <div class="doc_author">
29 <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 3.1
35 <a href="http://llvm.org/releases/3.0/docs/ReleaseNotes.html">LLVM 3.0
36 Release Notes</a>.</h1>
38 <!-- *********************************************************************** -->
40 <a name="intro">Introduction</a>
42 <!-- *********************************************************************** -->
46 <p>This document contains the release notes for the LLVM Compiler
47 Infrastructure, release 3.1. Here we describe the status of LLVM, including
48 major improvements from the previous release, improvements in various
49 subprojects of LLVM, and some of the current users of the code.
50 All LLVM releases may be downloaded from
51 the <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
53 <p>For more information about LLVM, including information about the latest
54 release, please check out the <a href="http://llvm.org/">main LLVM web
55 site</a>. If you have questions or comments,
56 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM
57 Developer's Mailing List</a> is a good place to send them.</p>
59 <p>Note that if you are reading this file from a Subversion checkout or the main
60 LLVM web page, this document applies to the <i>next</i> release, not the
61 current one. To see the release notes for a specific release, please see the
62 <a href="http://llvm.org/releases/">releases page</a>.</p>
67 <!-- *********************************************************************** -->
69 <a name="subproj">Sub-project Status Update</a>
71 <!-- *********************************************************************** -->
75 <p>The LLVM 3.1 distribution currently consists of code from the core LLVM
76 repository (which roughly includes the LLVM optimizers, code generators and
77 supporting tools), and the Clang repository. In addition to this code, the
78 LLVM Project includes other sub-projects that are in development. Here we
79 include updates on these subprojects.</p>
81 <!--=========================================================================-->
83 <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
88 <p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
89 C++, and Objective-C languages. Clang aims to provide a better user
90 experience through expressive diagnostics, a high level of conformance to
91 language standards, fast compilation, and low memory use. Like LLVM, Clang
92 provides a modular, library-based architecture that makes it suitable for
93 creating or integrating with other development tools. Clang is considered a
94 production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
95 (32- and 64-bit), and for Darwin/ARM targets.</p>
97 <p>In the LLVM 3.1 time-frame, the Clang team has made many improvements.
98 Highlights include:</p>
100 <li>Greatly expanded <a href="http://clang.llvm.org/cxx_status.html">C++11
101 support</a> including lambdas, initializer lists, constexpr, user-defined
102 literals, and atomics.</li>
103 <li>A new <a href="http://clang.llvm.org/docs/Tooling.html">tooling</a>
104 library to ease building of clang-based standalone tools.</li>
105 <li>Extended support for
106 <a href="http://clang.llvm.org/docs/ObjectiveCLiterals.html">literals in
107 Objective C</a>.</li>
110 <p>For more details about the changes to Clang since the 3.0 release, see the
111 <a href="http://clang.llvm.org/docs/ReleaseNotes.html">Clang release
114 <p>If Clang rejects your code but another compiler accepts it, please take a
115 look at the <a href="http://clang.llvm.org/compatibility.html">language
116 compatibility</a> guide to make sure this is not intentional or a known
121 <!--=========================================================================-->
123 <a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
128 <p><a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
129 <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
130 optimizers and code generators with LLVM's. It works with gcc-4.5 and gcc-4.6
131 (and partially with gcc-4.7), can target the x86-32/x86-64 and ARM processor
132 families, and has been successfully used on the Darwin, FreeBSD, KFreeBSD,
133 Linux and OpenBSD platforms. It fully supports Ada, C, C++ and Fortran. It
134 has partial support for Go, Java, Obj-C and Obj-C++.</p>
136 <p>The 3.1 release has the following notable changes:</p>
139 <li>Partial support for gcc-4.7. Ada support is poor, but other languages work
142 <li>Support for ARM processors. Some essential gcc headers that are needed to
143 build DragonEgg for ARM are not installed by gcc. To work around this,
144 copy the missing headers from the gcc source tree.</li>
146 <li>Better optimization for Fortran by exploiting the fact that Fortran scalar
147 arguments have 'restrict' semantics.</li>
149 <li>Better optimization for all languages by passing information about type
150 aliasing and type ranges to the LLVM optimizers.</li>
152 <li>A regression test-suite was added.</li>
157 <!--=========================================================================-->
159 <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
164 <p>The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
165 is a simple library that provides an implementation of the low-level
166 target-specific hooks required by code generation and other runtime
167 components. For example, when compiling for a 32-bit target, converting a
168 double to a 64-bit unsigned integer is compiled into a runtime call to the
169 "__fixunsdfdi" function. The compiler-rt library provides highly optimized
170 implementations of this and other low-level routines (some are 3x faster than
171 the equivalent libgcc routines).</p>
173 <p>As of 3.1, compiler-rt includes the helper functions for atomic operations,
174 allowing atomic operations on arbitrary-sized quantities to work. These
175 functions follow the specification defined by gcc and are used by clang.</p>
179 <!--=========================================================================-->
181 <a name="lldb">LLDB: Low Level Debugger</a>
186 <p><a href="http://lldb.llvm.org">LLDB</a> is a ground-up implementation of a
187 command line debugger, as well as a debugger API that can be used from other
188 applications. LLDB makes use of the Clang parser to provide high-fidelity
189 expression parsing (particularly for C++) and uses the LLVM JIT for target
194 <!--=========================================================================-->
196 <a name="libc++">libc++: C++ Standard Library</a>
201 <p>Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
202 licensed</a> under the MIT and UIUC license, allowing it to be used more
205 <p>Within the LLVM 3.1 time-frame there were the following highlights:</p>
208 <li>The <code><atomic></code> header is now passing all tests, when
209 compiling with clang and linking against the support code from
211 <li>FreeBSD now includes libc++ as part of the base system.</li>
212 <li>libc++ has been ported to Solaris and, in combination with libcxxrt and
213 clang, is working with a large body of existing code.</li>
218 <!--=========================================================================-->
220 <a name="vmkit">VMKit</a>
225 <p>The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation
226 of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
227 just-in-time compilation.</p>
229 <p>In the LLVM 3.1 time-frame, VMKit has had significant improvements on both
230 runtime and startup performance.</p>
235 <!--=========================================================================-->
237 <a name="Polly">Polly: Polyhedral Optimizer</a>
242 <p><a href="http://polly.llvm.org/">Polly</a> is an <em>experimental</em>
243 optimizer for data locality and parallelism. It currently provides high-level
244 loop optimizations and automatic parallelisation (using the OpenMP run time).
245 Work in the area of automatic SIMD and accelerator code generation was
248 <p>Within the LLVM 3.1 time-frame there were the following highlights:</p>
251 <li>Polly became an official LLVM project</li>
252 <li>Polly can be loaded directly into clang (enabled by '-O3 -mllvm -polly')</li>
253 <li>An automatic scheduling optimizer (derived
254 from <a href="http://pluto-compiler.sourceforge.net/">Pluto</a>) was
255 integrated. It performs loop transformations to optimize for data-locality
256 and parallelism. The transformations include, but are not limited to
257 interchange, fusion, fission, skewing and tiling.</li>
264 <!-- *********************************************************************** -->
266 <a name="externalproj">External Open Source Projects Using LLVM 3.1</a>
268 <!-- *********************************************************************** -->
272 <p>An exciting aspect of LLVM is that it is used as an enabling technology for
273 a lot of other language and tools projects. This section lists some of the
274 projects that have already been updated to work with LLVM 3.1.</p>
280 <p><a href="http://faust.grame.fr/">FAUST</a> is a compiled language for
281 real-time audio signal processing. The name FAUST stands for Functional
282 AUdio STream. Its programming model combines two approaches: functional
283 programming and block diagram composition. In addition with the C, C++, Java,
284 JavaScript output formats, the Faust compiler can generate LLVM bitcode, and
285 works with LLVM 2.7-3.1.</p>
289 <h3>Glasgow Haskell Compiler (GHC)</h3>
293 <p><a href="http://www.haskell.org/ghc/">GHC</a> is an open source compiler and
294 programming suite for Haskell, a lazy functional programming language. It
295 includes an optimizing static compiler generating good code for a variety of
296 platforms, together with an interactive system for convenient, quick
299 <p>GHC 7.0 and onwards include an LLVM code generator, supporting LLVM 2.8 and
308 <p><a href="https://github.com/JuliaLang/julia">Julia</a> is a high-level,
309 high-performance dynamic language for technical computing. It provides a
310 sophisticated compiler, distributed parallel execution, numerical accuracy,
311 and an extensive mathematical function library. The compiler uses type
312 inference to generate fast code without any type declarations, and uses
313 LLVM's optimization passes and JIT compiler. The
314 <a href="http://julialang.org/"> Julia Language</a> is designed
315 around multiple dispatch, giving programs a large degree of flexibility. It
316 is ready for use on many kinds of problems.</p>
320 <h3>LLVM D Compiler</h3>
324 <p><a href="https://github.com/ldc-developers/ldc">LLVM D Compiler</a> (LDC) is
325 a compiler for the D programming Language. It is based on the DMD frontend
326 and uses LLVM as backend.</p>
330 <h3>Open Shading Language</h3>
334 <p><a href="https://github.com/imageworks/OpenShadingLanguage/">Open Shading
335 Language (OSL)</a> is a small but rich language for programmable shading in
336 advanced global illumination renderers and other applications, ideal for
337 describing materials, lights, displacement, and pattern generation. It uses
338 LLVM to JIT complex shader networks to x86 code at runtime.</p>
340 <p>OSL was developed by Sony Pictures Imageworks for use in its in-house
341 renderer used for feature film animation and visual effects, and is
342 distributed as open source software with the "New BSD" license.</p>
346 <h3>Portable OpenCL (pocl)</h3>
350 <p>In addition to producing an easily portable open source OpenCL
351 implementation, another major goal of <a href="http://pocl.sourceforge.net/">
352 pocl</a> is improving performance portability of OpenCL programs with
353 compiler optimizations, reducing the need for target-dependent manual
354 optimizations. An important part of pocl is a set of LLVM passes used to
355 statically parallelize multiple work-items with the kernel compiler, even in
356 the presence of work-group barriers. This enables static parallelization of
357 the fine-grained static concurrency in the work groups in multiple ways
358 (SIMD, VLIW, superscalar,...).</p>
366 <p><a href="http://pure-lang.googlecode.com/">Pure</a> is an
367 algebraic/functional programming language based on term rewriting. Programs
368 are collections of equations which are used to evaluate expressions in a
369 symbolic fashion. The interpreter uses LLVM as a backend to JIT-compile Pure
370 programs to fast native code. Pure offers dynamic typing, eager and lazy
371 evaluation, lexical closures, a hygienic macro system (also based on term
372 rewriting), built-in list and matrix support (including list and matrix
373 comprehensions) and an easy-to-use interface to C and other programming
374 languages (including the ability to load LLVM bitcode modules, and inline C,
375 C++, Fortran and Faust code in Pure programs if the corresponding
376 LLVM-enabled compilers are installed).</p>
378 <p>Pure version 0.54 has been tested and is known to work with LLVM 3.1 (and
379 continues to work with older LLVM releases >= 2.5).</p>
383 <h3>TTA-based Co-design Environment (TCE)</h3>
387 <p><a href="http://tce.cs.tut.fi/">TCE</a> is a toolset for designing
388 application-specific processors (ASP) based on the Transport triggered
389 architecture (TTA). The toolset provides a complete co-design flow from C/C++
390 programs down to synthesizable VHDL/Verilog and parallel program binaries.
391 Processor customization points include the register files, function units,
392 supported operations, and the interconnection network.</p>
394 <p>TCE uses Clang and LLVM for C/C++ language support, target independent
395 optimizations and also for parts of code generation. It generates new
396 LLVM-based code generators "on the fly" for the designed TTA processors and
397 loads them in to the compiler backend as runtime libraries to avoid
398 per-target recompilation of larger parts of the compiler chain.</p>
404 <!-- *********************************************************************** -->
406 <a name="whatsnew">What's New in LLVM 3.1?</a>
408 <!-- *********************************************************************** -->
412 <p>This release includes a huge number of bug fixes, performance tweaks and
413 minor improvements. Some of the major improvements and new features are
414 listed in this section.</p>
416 <!--=========================================================================-->
418 <a name="majorfeatures">Major New Features</a>
423 <!-- Features that need text if they're finished for 3.1:
427 loop dependence analysis
428 CorrelatedValuePropagation
429 lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
430 Integrated assembler on by default for arm/thumb?
435 Analysis/RegionInfo.h + Dom Frontiers
436 SparseBitVector: used in LiveVar.
437 llvm/lib/Archive - replace with lib object?
440 <p>LLVM 3.1 includes several major changes and big features:</p>
443 <li><a href="../tools/clang/docs/AddressSanitizer.html">AddressSanitizer</a>,
444 a fast memory error detector.</li>
445 <li><a href="CodeGenerator.html#machineinstrbundle">MachineInstr Bundles</a>,
446 Support to model instruction bundling / packing.</li>
447 <li><a href="#armintegratedassembler">ARM Integrated Assembler</a>,
448 A full featured assembler and direct-to-object support for ARM.</li>
449 <li><a href="#blockplacement">Basic Block Placement</a>
450 Probability driven basic block placement.</li>
456 <!--=========================================================================-->
458 <a name="coreimprovements">LLVM IR and Core Improvements</a>
463 <p>LLVM IR has several new features for better support of new targets and that
464 expose new optimization opportunities:</p>
467 <li>A new type representing 16 bit <i>half</i> floating point values has
469 <li>IR now supports vectors of pointers, including vector GEPs.</li>
470 <li>Module flags have been introduced. They convey information about the
471 module as a whole to LLVM subsystems. This is currently used to encode
472 Objective C ABI information.</li>
473 <li>Loads can now have range metadata attached to them to describe the
474 possible values being loaded.</li>
475 <li>The <tt>llvm.ctlz</tt> and <tt>llvm.cttz</tt> intrinsics now have an
476 additional argument which indicates whether the behavior of the intrinsic
477 is undefined on a zero input. This can be used to generate more efficient
478 code on platforms that only have instructions which don't return the type
479 size when counting bits in 0.</li>
484 <!--=========================================================================-->
486 <a name="optimizer">Optimizer Improvements</a>
491 <p>In addition to many minor performance tweaks and bug fixes, this
492 release includes a few major enhancements and additions to the
496 <li>The loop unroll pass now is able to unroll loops with run-time trip counts.
497 This feature is turned off by default, and is enabled with the
498 <code>-unroll-runtime</code> flag.</li>
499 <li>A new basic-block autovectorization pass is available. Pass
500 <code>-vectorize</code> to run this pass along with some associated
501 post-vectorization cleanup passes. For more information, see the EuroLLVM
502 2012 slides: <a href="http://llvm.org/devmtg/2012-04-12/Slides/Hal_Finkel.pdf">
503 Autovectorization with LLVM</a>.</li>
504 <li>Inline cost heuristics have been completely overhauled and now closely
505 model constant propagation through call sites, disregard trivially dead
506 code costs, and can model C++ STL iterator patterns.</li>
511 <!--=========================================================================-->
513 <a name="mc">MC Level Improvements</a>
518 <p>The LLVM Machine Code (aka MC) subsystem was created to solve a number of
519 problems in the realm of assembly, disassembly, object file format handling,
520 and a number of other related areas that CPU instruction-set level tools work
521 in. For more information, please see
522 the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro
523 to the LLVM MC Project Blog Post</a>.</p>
526 <li>The integrated assembler can optionally emit debug information when
527 assembling a </tt>.s</tt> file. It can be enabled by passing the
528 <tt>-g</tt> option to <tt>llvm-mc</tt>.</li>
533 <!--=========================================================================-->
535 <a name="codegen">Target Independent Code Generator Improvements</a>
540 <p>We have changed the way that the Type Legalizer legalizes vectors. The type
541 legalizer now attempts to promote integer elements. This enabled the
542 implementation of vector-select. Additionally, we see a performance boost on
543 workloads which use vectors of chars and shorts, since they are now promoted
544 to 32-bit types, which are better supported by the SIMD instruction set.
545 Floating point types are still widened as before.</p>
548 <p>We have put a significant amount of work into the code generator
549 infrastructure, which allows us to implement more aggressive algorithms and
550 make it run faster:</p>
553 <li>TableGen can now synthesize register classes that are only needed to
554 represent combinations of constraints from instructions and sub-registers.
555 The synthetic register classes inherit most of their properties form their
556 closest user-defined super-class.</li>
557 <li><code>MachineRegisterInfo</code> now allows the reserved registers to be
558 frozen when register allocation starts. Target hooks should use the
559 <code>MRI->canReserveReg(FramePtr)</code> method to avoid accidentally
560 disabling frame pointer elimination during register allocation.</li>
561 <li>A new kind of <code>MachineOperand</code> provides a compact
562 representation of large clobber lists on call instructions. The register
563 mask operand references a bit mask of preserved registers. Everything else
565 <li>The DWARF debug info writer gained support for emitting data for the
566 <a href="SourceLevelDebugging.html#acceltable">name accelerator tables
567 DWARF extension</a>. It is used by LLDB to speed up name lookup.</li>
570 <p> We added new TableGen infrastructure to support bundling for
571 Very Long Instruction Word (VLIW) architectures. TableGen can now
572 automatically generate a deterministic finite automaton from a VLIW
573 target's schedule description which can be queried to determine
574 legal groupings of instructions in a bundle.</p>
576 <p> We have added a new target independent VLIW packetizer based on the
577 DFA infrastructure to group machine instructions into bundles.</p>
582 <a name="blockplacement">Basic Block Placement</a>
585 <p>A probability based block placement and code layout algorithm was added to
586 LLVM's code generator. This layout pass supports probabilities derived from
587 static heuristics as well as source code annotations such as
588 <code>__builtin_expect</code>.</p>
591 <!--=========================================================================-->
593 <a name="x86">X86-32 and X86-64 Target Improvements</a>
598 <p>New features and major changes in the X86 target include:</p>
601 <li>Greatly improved support for AVX2.</li>
602 <li>Lots of bug fixes and improvements for AVX1.</li>
603 <li>Support for the FMA4 and XOP instruction set extensions.</li>
604 <li>Call instructions use the new register mask operands for faster compile
605 times and better support for different calling conventions. The old WINCALL
606 instructions are no longer needed.</li>
607 <li>DW2 Exception Handling is enabled on Cygwin and MinGW.</li>
608 <li>Support for implicit TLS model used with MSVC runtime.</li>
613 <!--=========================================================================-->
615 <a name="ARM">ARM Target Improvements</a>
620 <p>New features of the ARM target include:</p>
623 <li>The constant island pass now supports basic block and constant pool entry
624 alignments greater than 4 bytes.</li>
625 <li>On Darwin, the ARM target now has a full-featured integrated assembler.
630 <a name="armintegratedassembler">ARM Integrated Assembler</a>
633 <p>The ARM target now includes a full featured macro assembler, including
634 direct-to-object module support for clang. The assembler is currently enabled
635 by default for Darwin only pending testing and any additional necessary
636 platform specific support for Linux.</p>
638 <p>Full support is included for Thumb1, Thumb2 and ARM modes, along with
639 subtarget and CPU specific extensions for VFP2, VFP3 and NEON.</p>
641 <p>The assembler is Unified Syntax only (see ARM Architecural Reference Manual
642 for details). While there is some, and growing, support for pre-unfied (divided)
643 syntax, there are still significant gaps in that support.</p>
647 <!--=========================================================================-->
649 <a name="MIPS">MIPS Target Improvements</a>
653 New features and major changes in the MIPS target include:</p>
656 <li>MIPS32 little-endian direct object code emission is functional.</li>
657 <li>MIPS64 little-endian code generation is largely functional for N64 ABI in assembly printing mode with the exception of handling of long double (f128) type.</li>
658 <li>Support for new instructions has been added, which includes swap-bytes
659 instructions (WSBH and DSBH), floating point multiply-add/subtract and
660 negative multiply-add/subtract instructions, and floating
661 point load/store instructions with reg+reg addressing (LWXC1, etc.)</li>
662 <li>Various fixes to improve performance have been implemented.</li>
663 <li>Post-RA scheduling is now enabled at -O3.</li>
664 <li>Support for soft-float code generation has been added.</li>
665 <li>clang driver's support for MIPS 64-bits targets.</li>
666 <li>Support for MIPS floating point ABI option in clang driver.</li>
670 <!--=========================================================================-->
672 <a name="PTX">PTX Target Improvements</a>
677 <p>An outstanding conditional inversion bug was fixed in this release.</p>
679 <p><b>NOTE</b>: LLVM 3.1 marks the last release of the PTX back-end, in its
680 current form. The back-end is currently being replaced by the NVPTX
681 back-end, currently in SVN ToT.</p>
685 <!--=========================================================================-->
687 <a name="OtherTS">Other Target Specific Improvements</a>
693 <li>Support for Qualcomm's Hexagon VLIW processor has been added.</li>
698 <!--=========================================================================-->
700 <a name="changes">Major Changes and Removed Features</a>
705 <p>If you're already an LLVM user or developer with out-of-tree changes based on
706 LLVM 3.1, this section lists some "gotchas" that you may run into upgrading
707 from the previous release.</p>
710 <li>LLVM's build system now requires a python 2 interpreter to be present at
711 build time. A perl interpreter is no longer required.</li>
712 <li>The C backend has been removed. It had numerous problems, to the point of
713 not being able to compile any nontrivial program.</li>
714 <li>The Alpha, Blackfin and SystemZ targets have been removed due to lack of
716 <li>LLVM 3.1 removes support for reading LLVM 2.9 bitcode files. Going
717 forward, we aim for all future versions of LLVM to read bitcode files and
718 <tt>.ll</tt> files produced by LLVM 3.0 and later.</li>
719 <li>The <tt>unwind</tt> instruction is now gone. With the introduction of the
720 new exception handling system in LLVM 3.0, the <tt>unwind</tt> instruction
721 became obsolete.</li>
722 <li>LLVM 3.0 and earlier automatically added the returns_twice fo functions
723 like setjmp based on the name. This functionality was removed in 3.1.
724 This affects Clang users, if -ffreestanding is used.</li>
729 <!--=========================================================================-->
731 <a name="api_changes">Internal API Changes</a>
736 <p>In addition, many APIs have changed in this release. Some of the major
737 LLVM API changes are:</p>
740 <li>Target specific options have been moved from global variables to members
741 on the new <code>TargetOptions</code> class, which is local to each
742 <code>TargetMachine</code>. As a consequence, the associated flags will
743 no longer be accepted by <tt>clang -mllvm</tt>. This includes:
745 <li><code>llvm::PrintMachineCode</code></li>
746 <li><code>llvm::NoFramePointerElim</code></li>
747 <li><code>llvm::NoFramePointerElimNonLeaf</code></li>
748 <li><code>llvm::DisableFramePointerElim(const MachineFunction &)</code></li>
749 <li><code>llvm::LessPreciseFPMADOption</code></li>
750 <li><code>llvm::LessPrecideFPMAD()</code></li>
751 <li><code>llvm::NoExcessFPPrecision</code></li>
752 <li><code>llvm::UnsafeFPMath</code></li>
753 <li><code>llvm::NoInfsFPMath</code></li>
754 <li><code>llvm::NoNaNsFPMath</code></li>
755 <li><code>llvm::HonorSignDependentRoundingFPMathOption</code></li>
756 <li><code>llvm::HonorSignDependentRoundingFPMath()</code></li>
757 <li><code>llvm::UseSoftFloat</code></li>
758 <li><code>llvm::FloatABIType</code></li>
759 <li><code>llvm::NoZerosInBSS</code></li>
760 <li><code>llvm::JITExceptionHandling</code></li>
761 <li><code>llvm::JITEmitDebugInfo</code></li>
762 <li><code>llvm::JITEmitDebugInfoToDisk</code></li>
763 <li><code>llvm::GuaranteedTailCallOpt</code></li>
764 <li><code>llvm::StackAlignmentOverride</code></li>
765 <li><code>llvm::RealignStack</code></li>
766 <li><code>llvm::DisableJumpTables</code></li>
767 <li><code>llvm::EnableFastISel</code></li>
768 <li><code>llvm::getTrapFunctionName()</code></li>
769 <li><code>llvm::EnableSegmentedStacks</code></li>
772 <li>The <code>MDBuilder</code> class has been added to simplify the creation
778 <!--=========================================================================-->
780 <a name="tools_changes">Tools Changes</a>
785 <p>In addition, some tools have changed in this release. Some of the changes
790 <li><tt>llvm-stress</tt> is a command line tool for generating random
791 <tt>.ll</tt> files to fuzz different LLVM components. </li>
792 <li>The <tt>llvm-ld</tt> tool has been removed. The clang driver provides a
793 more reliable solution for turning a set of bitcode files into a binary.
794 To merge bitcode files <tt>llvm-link</tt> can be used instead.</li>
800 <!--=========================================================================-->
802 <a name="python">Python Bindings</a>
807 <p>Officially supported Python bindings have been added! Feature support is far
808 from complete. The current bindings support interfaces to:</p>
810 <li>Object File Interface</li>
811 <li>Disassembler</li>
814 <p>Using the Object File Interface, it is possible to inspect binary object files.
815 Think of it as a Python version of readelf or llvm-objdump.</p>
817 <p>Support for additional features is currently being developed by community
818 contributors. If you are interested in shaping the direction of the Python
819 bindings, please express your intent on IRC or the developers list.</p>
825 <!-- *********************************************************************** -->
827 <a name="knownproblems">Known Problems</a>
829 <!-- *********************************************************************** -->
833 <p>LLVM is generally a production quality compiler, and is used by a broad range
834 of applications and shipping in many products. That said, not every
835 subsystem is as mature as the aggregate, particularly the more obscure
836 targets. If you run into a problem, please check the <a
837 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
838 there isn't already one or ask on the <a
839 href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev
842 <p>Known problem areas include:</p>
845 <li>The CellSPU, MSP430, PTX and XCore backends are experimental.</li>
847 <li>The integrated assembler, disassembler, and JIT is not supported by
848 several targets. If an integrated assembler is not supported, then a
849 system assembler is required. For more details, see the <a
850 href="CodeGenerator.html#targetfeatures">Target Features Matrix</a>.
856 <!-- *********************************************************************** -->
858 <a name="additionalinfo">Additional Information</a>
860 <!-- *********************************************************************** -->
864 <p>A wide variety of additional information is available on
865 the <a href="http://llvm.org/">LLVM web page</a>, in particular in
866 the <a href="http://llvm.org/docs/">documentation</a> section. The web page
867 also contains versions of the API documentation which is up-to-date with the
868 Subversion version of the source code. You can access versions of these
869 documents specific to this release by going into the "<tt>llvm/doc/</tt>"
870 directory in the LLVM tree.</p>
872 <p>If you have any questions or comments about LLVM, please feel free to contact
873 us via the <a href="http://llvm.org/docs/#maillist"> mailing lists</a>.</p>
877 <!-- *********************************************************************** -->
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