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11 <h1>LLVM 3.0 Release Notes</h1>
13 <img align=right src="http://llvm.org/img/DragonSmall.png"
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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 3.0</a></li>
20 <li><a href="#whatsnew">What's New in LLVM 3.0?</a></li>
21 <li><a href="GettingStarted.html">Installation Instructions</a></li>
22 <li><a href="#knownproblems">Known Problems</a></li>
23 <li><a href="#additionalinfo">Additional Information</a></li>
26 <div class="doc_author">
27 <p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
31 <h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.0
34 <a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9
35 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 3.0. 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>
65 <!-- Features that need text if they're finished for 3.1:
69 loop dependence analysis
70 CorrelatedValuePropagation
71 lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
74 <!-- *********************************************************************** -->
76 <a name="subproj">Sub-project Status Update</a>
78 <!-- *********************************************************************** -->
82 The LLVM 3.0 distribution currently consists of code from the core LLVM
83 repository (which roughly includes the LLVM optimizers, code generators
84 and supporting tools), the Clang repository and the llvm-gcc repository. In
85 addition to this code, the LLVM Project includes other sub-projects that are in
86 development. Here we include updates on these subprojects.
89 <!--=========================================================================-->
91 <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
96 <p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
97 C++, and Objective-C languages. Clang aims to provide a better user experience
98 through expressive diagnostics, a high level of conformance to language
99 standards, fast compilation, and low memory use. Like LLVM, Clang provides a
100 modular, library-based architecture that makes it suitable for creating or
101 integrating with other development tools. Clang is considered a
102 production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
103 (32- and 64-bit), and for darwin/arm targets.</p>
105 <p>In the LLVM 3.0 time-frame, the Clang team has made many improvements:</p>
108 <li>Greatly improved support for building C++ applications, with greater stability and better diagnostics.</li>
110 <li><a href="http://clang.llvm.org/cxx_status.html">Improved support</a> for the <a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50372 ">C++ 2011</a> standard, including implementations of non-static data member initializers, alias templates, delegating constructors, the range-based for loop, and implicitly-generated move constructors and move assignment operators, among others.</li>
112 <li>Implemented support for some features of the upcoming C1x standard, including static assertions and generic selections.</li>
114 <li>Better detection of include and linking paths for system headers and libraries, especially for Linux distributions.</li>
116 <li>Implemented support for <a href="http://clang.llvm.org/docs/AutomaticReferenceCounting.html">Automatic Reference Counting</a> for Objective-C.</li>
118 <li>Implemented a number of optimizations in <tt>libclang</tt>, the Clang C interface, to improve the performance of code completion and the mapping from source locations to abstract syntax tree nodes.</li>
122 <p>If Clang rejects your code but another compiler accepts it, please take a
123 look at the <a href="http://clang.llvm.org/compatibility.html">language
124 compatibility</a> guide to make sure this is not intentional or a known issue.
129 <!--=========================================================================-->
131 <a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
136 <a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
137 <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
138 optimizers and code generators with LLVM's.
139 Currently it requires a patched version of gcc-4.5.
140 The plugin can target the x86-32 and x86-64 processor families and has been
141 used successfully on the Darwin, FreeBSD and Linux platforms.
142 The Ada, C, C++ and Fortran languages work well.
143 The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is
144 not known whether the compiled code actually works or not!
148 The 3.0 release has the following notable changes:
157 <!--=========================================================================-->
159 <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
164 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 components.
167 For example, when compiling for a 32-bit target, converting a double to a 64-bit
168 unsigned integer is compiled into a runtime call to the "__fixunsdfdi"
169 function. The compiler-rt library provides highly optimized implementations of
170 this and other low-level routines (some are 3x faster than the equivalent
171 libgcc routines).</p>
173 <p>In the LLVM 3.0 timeframe,</p>
177 <!--=========================================================================-->
179 <a name="lldb">LLDB: Low Level Debugger</a>
184 <a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM
185 umbrella of projects. LLDB is a next generation, high-performance debugger. It
186 is built as a set of reusable components which highly leverage existing
187 libraries in the larger LLVM Project, such as the Clang expression parser, the
188 LLVM disassembler and the LLVM JIT.</p>
191 LLDB is has advanced by leaps and bounds in the 3.0 timeframe. It is
192 dramatically more stable and useful, and includes both a new <a
193 href="http://lldb.llvm.org/tutorial.html">tutorial</a> and a <a
194 href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with
199 <!--=========================================================================-->
201 <a name="libc++">libc++: C++ Standard Library</a>
206 <a href="http://libcxx.llvm.org/">libc++</a> is another new member of the LLVM
207 family. It is an implementation of the C++ standard library, written from the
208 ground up to specifically target the forthcoming C++'0X standard and focus on
209 delivering great performance.</p>
212 In the LLVM 3.0 timeframe,</p>
215 Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
216 licensed</a> under the MIT and UIUC license, allowing it to be used more
223 <!--=========================================================================-->
225 <a name="LLBrowse">LLBrowse: IR Browser</a>
230 <a href="http://llvm.org/svn/llvm-project/llbrowse/trunk/doc/LLBrowse.html">
231 LLBrowse</a> is an interactive viewer for LLVM modules. It can load any LLVM
232 module and displays its contents as an expandable tree view, facilitating an
233 easy way to inspect types, functions, global variables, or metadata nodes. It
234 is fully cross-platform, being based on the popular wxWidgets GUI toolkit.
238 <!--=========================================================================-->
240 <a name="vmkit">VMKit</a>
244 <p>The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation
245 of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
246 just-in-time compilation. As of LLVM 3.0, VMKit now supports generational
247 garbage collectors. The garbage collectors are provided by the MMTk framework,
248 and VMKit can be configured to use one of the numerous implemented collectors
254 <!--=========================================================================-->
257 <a name="klee">KLEE: A Symbolic Execution Virtual Machine</a>
262 <a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for
263 programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths
264 through the application and records state transitions that lead to fault
265 states. This allows it to construct testcases that lead to faults and can even
266 be used to verify some algorithms.
274 <!-- *********************************************************************** -->
276 <a name="externalproj">External Open Source Projects Using LLVM 3.0</a>
278 <!-- *********************************************************************** -->
282 <p>An exciting aspect of LLVM is that it is used as an enabling technology for
283 a lot of other language and tools projects. This section lists some of the
284 projects that have already been updated to work with LLVM 3.0.</p>
286 <!--=========================================================================-->
287 <h3>AddressSanitizer</h3>
291 <p><a href="http://code.google.com/p/address-sanitizer/">AddressSanitizer</a>
292 uses compiler instrumentation and a specialized malloc library to find C/C++
293 bugs such as use-after-free and out-of-bound accesses to heap, stack, and
294 globals. The key feature of the tool is speed: the average slowdown
295 introduced by AddressSanitizer is less than 2x.</p>
299 <!--=========================================================================-->
304 <p><a href="http://www.clamav.net">Clam AntiVirus</a> is an open source (GPL)
305 anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail
308 <p>Since version 0.96 it
309 has <a href="http://vrt-sourcefire.blogspot.com/2010/09/introduction-to-clamavs-low-level.html">bytecode
310 signatures</a> that allow writing detections for complex malware.</p>
312 <p>It uses LLVM's JIT to speed up the execution of bytecode on X86, X86-64,
313 PPC32/64, falling back to its own interpreter otherwise. The git version was
314 updated to work with LLVM 3.0.</p>
318 <!--=========================================================================-->
319 <!-- FIXME: Comment out
320 <h3>Crack Programming Language</h3>
324 <a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide the
325 ease of development of a scripting language with the performance of a compiled
326 language. The language derives concepts from C++, Java and Python, incorporating
327 object-oriented programming, operator overloading and strong typing.</p>
331 <!--=========================================================================-->
332 <h3>Glasgow Haskell Compiler (GHC)</h3>
336 <p>GHC is an open source, state-of-the-art programming suite for Haskell, a
337 standard lazy functional programming language. It includes an optimizing
338 static compiler generating good code for a variety of platforms, together
339 with an interactive system for convenient, quick development.</p>
341 <p>GHC 7.0 and onwards include an LLVM code generator, supporting LLVM 2.8 and
342 later. Since LLVM 2.9, GHC now includes experimental support for the ARM
343 platform with LLVM 3.0.</p>
347 <!--=========================================================================-->
352 <p><a href="http://botwars.tk/gwscript/">gwXscript</a> is an object oriented,
353 aspect oriented programming language which can create both executables (ELF,
354 EXE) and shared libraries (DLL, SO, DYNLIB). The compiler is implemented in
355 its own language and translates scripts into LLVM-IR which can be optimized
356 and translated into native code by the LLVM framework. Source code in
357 gwScript contains definitions that expand the namespaces. So you can build
358 your project and simply 'plug out' features by removing a file. The remaining
359 project does not leave scars since you directly separate concerns by the
360 'template' feature of gwX. It is also possible to add new features to a
361 project by just adding files and without editing the original project. This
362 language is used for example to create games or content management systems
363 that should be extendable.</p>
365 <p>gwXscript is strongly typed and offers comfort with its native types string,
366 hash and array. You can easily write new libraries in gwXscript or native
367 code. gwXscript is type safe and users should not be able to crash your
368 program or execute malicious code except code that is eating CPU time.</p>
372 <!--=========================================================================-->
377 <p>An open source, cross-platform implementation of C# and the CLR that is
378 binary compatible with Microsoft.NET. Has an optional, dynamically-loaded
379 LLVM code generation backend in Mini, the JIT compiler.</p>
381 <p>Note that we use a Git mirror of LLVM with some patches. See:
382 https://github.com/mono/llvm</p>
386 <!--=========================================================================-->
387 <h3>Portable OpenCL (pocl)</h3>
391 <p>Portable OpenCL is an open source implementation of the OpenCL standard which
392 can be easily adapted for new targets. One of the goals of the project is
393 improving performance portability of OpenCL programs, avoiding the need for
394 target-dependent manual optimizations. A "native" target is included, which
395 allows running OpenCL kernels on the host (CPU).</p>
399 <!--=========================================================================-->
403 <p><a href="http://pure-lang.googlecode.com/">Pure</a> is an
404 algebraic/functional programming language based on term rewriting. Programs
405 are collections of equations which are used to evaluate expressions in a
406 symbolic fashion. The interpreter uses LLVM as a backend to JIT-compile Pure
407 programs to fast native code. Pure offers dynamic typing, eager and lazy
408 evaluation, lexical closures, a hygienic macro system (also based on term
409 rewriting), built-in list and matrix support (including list and matrix
410 comprehensions) and an easy-to-use interface to C and other programming
411 languages (including the ability to load LLVM bitcode modules, and inline C,
412 C++, Fortran and Faust code in Pure programs if the corresponding LLVM-enabled
413 compilers are installed).</p>
415 <p>Pure version 0.48 has been tested and is known to work with LLVM 3.0
416 (and continues to work with older LLVM releases >= 2.5).</p>
420 <!--=========================================================================-->
421 <h3>Renderscript</h3>
425 <p><a href="http://developer.android.com/guide/topics/renderscript/index.html">Renderscript</a>
426 is Android's advanced 3D graphics rendering and compute API. It provides a
427 portable C99-based language with extensions to facilitate common use cases
428 for enhancing graphics and thread level parallelism. The Renderscript
429 compiler frontend is based on Clang/LLVM. It emits a portable bitcode format
430 for the actual compiled script code, as well as reflects a Java interface for
431 developers to control the execution of the compiled bitcode. Executable
432 machine code is then generated from this bitcode by an LLVM backend on the
433 device. Renderscript is thus able to provide a mechanism by which Android
434 developers can improve performance of their applications while retaining
439 <!--=========================================================================-->
444 <p><a href="http://safecode.cs.illinois.edu">SAFECode</a> is a memory safe C/C++
445 compiler built using LLVM. It takes standard, unannotated C/C++ code,
446 analyzes the code to ensure that memory accesses and array indexing
447 operations are safe, and instruments the code with run-time checks when
448 safety cannot be proven statically. SAFECode can be used as a debugging aid
449 (like Valgrind) to find and repair memory safety bugs. It can also be used
450 to protect code from security attacks at run-time.</p>
454 <!--=========================================================================-->
455 <h3>TTA-based Co-design Environment (TCE)</h3>
459 <p>TCE is a toolset for designing application-specific processors (ASP) based on
460 the Transport triggered architecture (TTA). The toolset provides a complete
461 co-design flow from C/C++ programs down to synthesizable VHDL and parallel
462 program binaries. Processor customization points include the register files,
463 function units, supported operations, and the interconnection network.</p>
465 <p>TCE uses Clang and LLVM for C/C++ language support, target independent
466 optimizations and also for parts of code generation. It generates new
467 LLVM-based code generators <i>on the fly</i> for the designed TTA processors
468 and loads them in to the compiler backend as runtime libraries to avoid
469 per-target recompilation of larger parts of the compiler chain.</p>
473 <!--=========================================================================-->
474 <h3>Tart Programming Language</h3>
478 <p><a href="http://code.google.com/p/tart/">Tart</a> is a general-purpose,
479 strongly typed programming language designed for application
480 developers. Strongly inspired by Python and C#, Tart focuses on practical
481 solutions for the professional software developer, while avoiding the clutter
482 and boilerplate of legacy languages like Java and C++. Although Tart is still
483 in development, the current implementation supports many features expected of
484 a modern programming language, such as garbage collection, powerful
485 bidirectional type inference, a greatly simplified syntax for template
486 metaprogramming, closures and function literals, reflection, operator
487 overloading, explicit mutability and immutability, and much more. Tart is
488 flexible enough to accommodate a broad range of programming styles and
489 philosophies, while maintaining a strong commitment to simplicity, minimalism
490 and elegance in design.</p>
494 <!--=========================================================================-->
499 <p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open
500 source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many
501 other front-ends, PinaVM actually executes the elaboration of the
502 program analyzed using LLVM's JIT infrastructure. It later enriches the
503 bitcode with SystemC-specific information.</p>
508 <!--=========================================================================-->
510 <h3 id="icedtea">IcedTea Java Virtual Machine Implementation</h3>
514 <a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a
515 harness to build OpenJDK using only free software build tools and to provide
516 replacements for the not-yet free parts of OpenJDK. One of the extensions that
517 IcedTea provides is a new JIT compiler named <a
518 href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM
519 to provide native code generation without introducing processor-dependent
523 <p> OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested
524 and are known to work with LLVM 3.0 (and continue to work with older LLVM
525 releases >= 2.6 as well).</p>
529 <!--=========================================================================-->
531 <h3>Polly - Polyhedral optimizations for LLVM</h3>
534 <p>Polly is a project that aims to provide advanced memory access optimizations
535 to better take advantage of SIMD units, cache hierarchies, multiple cores or
536 even vector accelerators for LLVM. Built around an abstract mathematical
537 description based on Z-polyhedra, it provides the infrastructure to develop
538 advanced optimizations in LLVM and to connect complex external optimizers. In
539 its first year of existence Polly already provides an exact value-based
540 dependency analysis as well as basic SIMD and OpenMP code generation support.
541 Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality
546 <!--=========================================================================-->
551 <p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment
552 for running Ruby code which strives to write as much of the implementation in
553 Ruby as possible. Combined with a bytecode interpreting VM, it uses LLVM to
554 optimize and compile ruby code down to machine code. Techniques such as type
555 feedback, method inlining, and deoptimization are all used to remove dynamism
556 from ruby execution and increase performance.</p>
560 <!--=========================================================================-->
563 <a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a>
568 <a href="http://faust.grame.fr">FAUST</a> is a compiled language for real-time
569 audio signal processing. The name FAUST stands for Functional AUdio STream. Its
570 programming model combines two approaches: functional programming and block
571 diagram composition. In addition with the C, C++, JAVA output formats, the
572 Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7-3.0.</p>
579 <!-- *********************************************************************** -->
581 <a name="whatsnew">What's New in LLVM 3.0?</a>
583 <!-- *********************************************************************** -->
587 <p>This release includes a huge number of bug fixes, performance tweaks and
588 minor improvements. Some of the major improvements and new features are listed
592 <!--=========================================================================-->
594 <a name="majorfeatures">Major New Features</a>
599 <p>LLVM 3.0 includes several major new capabilities:</p>
611 <!--=========================================================================-->
613 <a name="coreimprovements">LLVM IR and Core Improvements</a>
617 <p>LLVM IR has several new features for better support of new targets and that
618 expose new optimization opportunities:</p>
628 <!--=========================================================================-->
630 <a name="optimizer">Optimizer Improvements</a>
635 <p>In addition to a large array of minor performance tweaks and bug fixes, this
636 release includes a few major enhancements and additions to the optimizers:</p>
648 <!--=========================================================================-->
650 <a name="mc">MC Level Improvements</a>
655 The LLVM Machine Code (aka MC) subsystem was created to solve a number
656 of problems in the realm of assembly, disassembly, object file format handling,
657 and a number of other related areas that CPU instruction-set level tools work
666 <p>For more information, please see the <a
667 href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the
668 LLVM MC Project Blog Post</a>.
673 <!--=========================================================================-->
675 <a name="codegen">Target Independent Code Generator Improvements</a>
680 <p>We have put a significant amount of work into the code generator
681 infrastructure, which allows us to implement more aggressive algorithms and make
691 <!--=========================================================================-->
693 <a name="x86">X86-32 and X86-64 Target Improvements</a>
697 <p>New features and major changes in the X86 target include:
701 <li>The CRC32 intrinsics have been renamed. The intrinsics were previously
702 @llvm.x86.sse42.crc32.[8|16|32] and @llvm.x86.sse42.crc64.[8|64]. They have
703 been renamed to @llvm.x86.sse42.crc32.32.[8|16|32] and
704 @llvm.x86.sse42.crc32.64.[8|64].</li>
710 <!--=========================================================================-->
712 <a name="ARM">ARM Target Improvements</a>
716 <p>New features of the ARM target include:
726 <!--=========================================================================-->
728 <a name="OtherTS">Other Target Specific Improvements</a>
739 <!--=========================================================================-->
741 <a name="changes">Major Changes and Removed Features</a>
746 <p>If you're already an LLVM user or developer with out-of-tree changes based on
747 LLVM 2.9, this section lists some "gotchas" that you may run into upgrading
748 from the previous release.</p>
751 <li>The <code>LLVMC</code> front end code was removed while separating
752 out language independence.</li>
753 <li>The <code>LowerSetJmp</code> pass wasn't used effectively by any
754 target and has been removed.</li>
755 <li>The old <code>TailDup</code> pass was not used in the standard pipeline
756 and was unable to update ssa form, so it has been removed.
757 <li>The syntax of volatile loads and stores in IR has been changed to
758 "<code>load volatile</code>"/"<code>store volatile</code>". The old
759 syntax ("<code>volatile load</code>"/"<code>volatile store</code>")
760 is still accepted, but is now considered deprecated.</li>
761 <li>The old atomic intrinscs (<code>llvm.memory.barrier</code> and
762 <code>llvm.atomic.*</code>) are now gone. Please use the new atomic
763 instructions, described in the <a href="Atomics.html">atomics guide</a>.
766 <h4>Windows (32-bit)</h4>
769 <li>On Win32(MinGW32 and MSVC), Windows 2000 will not be supported.
770 Windows XP or higher is required.</li>
776 <!--=========================================================================-->
778 <a name="api_changes">Internal API Changes</a>
783 <p>In addition, many APIs have changed in this release. Some of the major
784 LLVM API changes are:</p>
787 <li>The biggest and most pervasive change is that llvm::Type's are no longer
788 returned or accepted as 'const' values. Instead, just pass around non-const
791 <li><code>PHINode::reserveOperandSpace</code> has been removed. Instead, you
792 must specify how many operands to reserve space for when you create the
793 PHINode, by passing an extra argument into <code>PHINode::Create</code>.</li>
795 <li>PHINodes no longer store their incoming BasicBlocks as operands. Instead,
796 the list of incoming BasicBlocks is stored separately, and can be accessed
797 with new functions <code>PHINode::block_begin</code>
798 and <code>PHINode::block_end</code>.</li>
800 <li>Various functions now take an <code>ArrayRef</code> instead of either a pair
801 of pointers (or iterators) to the beginning and end of a range, or a pointer
802 and a length. Others now return an <code>ArrayRef</code> instead of a
803 reference to a <code>SmallVector</code> or <code>std::vector</code>. These
806 <!-- Please keep this list sorted. -->
807 <li><code>CallInst::Create</code></li>
808 <li><code>ComputeLinearIndex</code> (in <code>llvm/CodeGen/Analysis.h</code>)</li>
809 <li><code>ConstantArray::get</code></li>
810 <li><code>ConstantExpr::getExtractElement</code></li>
811 <li><code>ConstantExpr::getGetElementPtr</code></li>
812 <li><code>ConstantExpr::getInBoundsGetElementPtr</code></li>
813 <li><code>ConstantExpr::getIndices</code></li>
814 <li><code>ConstantExpr::getInsertElement</code></li>
815 <li><code>ConstantExpr::getWithOperands</code></li>
816 <li><code>ConstantFoldCall</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li>
817 <li><code>ConstantFoldInstOperands</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li>
818 <li><code>ConstantVector::get</code></li>
819 <li><code>DIBuilder::createComplexVariable</code></li>
820 <li><code>DIBuilder::getOrCreateArray</code></li>
821 <li><code>ExtractValueInst::Create</code></li>
822 <li><code>ExtractValueInst::getIndexedType</code></li>
823 <li><code>ExtractValueInst::getIndices</code></li>
824 <li><code>FindInsertedValue</code> (in <code>llvm/Analysis/ValueTracking.h</code>)</li>
825 <li><code>gep_type_begin</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li>
826 <li><code>gep_type_end</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li>
827 <li><code>GetElementPtrInst::Create</code></li>
828 <li><code>GetElementPtrInst::CreateInBounds</code></li>
829 <li><code>GetElementPtrInst::getIndexedType</code></li>
830 <li><code>InsertValueInst::Create</code></li>
831 <li><code>InsertValueInst::getIndices</code></li>
832 <li><code>InvokeInst::Create</code></li>
833 <li><code>IRBuilder::CreateCall</code></li>
834 <li><code>IRBuilder::CreateExtractValue</code></li>
835 <li><code>IRBuilder::CreateGEP</code></li>
836 <li><code>IRBuilder::CreateInBoundsGEP</code></li>
837 <li><code>IRBuilder::CreateInsertValue</code></li>
838 <li><code>IRBuilder::CreateInvoke</code></li>
839 <li><code>MDNode::get</code></li>
840 <li><code>MDNode::getIfExists</code></li>
841 <li><code>MDNode::getTemporary</code></li>
842 <li><code>MDNode::getWhenValsUnresolved</code></li>
843 <li><code>SimplifyGEPInst</code> (in <code>llvm/Analysis/InstructionSimplify.h</code>)</li>
844 <li><code>TargetData::getIndexedOffset</code></li>
847 <li>All forms of <code>StringMap::getOrCreateValue</code> have been remove
848 except for the one which takes a <code>StringRef</code>.</li>
850 <li>The <code>LLVMBuildUnwind</code> function from the C API was removed. The
851 LLVM <code>unwind</code> instruction has been deprecated for a long time and
852 isn't used by the current front-ends. So this was removed during the
853 exception handling rewrite.</li>
855 <li>The <code>LLVMAddLowerSetJmpPass</code> function from the C API was removed
856 because the <code>LowerSetJmp</code> pass was removed.</li>
858 <li>The <code>DIBuilder</code> interface used by front ends to encode debugging
859 information in the LLVM IR now expects clients to use <code>DIBuilder::finalize()</code>
860 at the end of translation unit to complete debugging information encoding.</li>
862 <li>The way the type system works has been rewritten: <code>PATypeHolder</code>
863 and <code>OpaqueType</code> are gone, and all APIs deal with <code>Type*</code>
864 instead of <code>const Type*</code>.
865 If you need to create recursive structures, then create a named structure,
866 and use <code>setBody()</code> when all its elements are built.
867 Type merging and refining is gone too: named structures are not
868 merged with other structures, even if their layout is identical.
869 (of course anonymous structures are still uniqued by layout).
872 <li>TargetSelect.h moved to Support/ from Target/</li>
874 <li>UpgradeIntrinsicCall no longer upgrades pre-2.9 intrinsic calls
875 (for example <code>llvm.memset.i32</code>).</li>
877 <li>It is mandatory to initialize all out-of-tree passes too and their dependencies now with
878 <code>INITIALIZE_PASS{BEGIN,END,}</code> and <code>INITIALIZE_{PASS,AG}_DEPENDENCY</code>.</li>
880 <li>The interface for MemDepResult in MemoryDependenceAnalysis has been enhanced
881 with new return types Unknown and NonFuncLocal, in addition to the existing
882 types Clobber, Def, and NonLocal.</li>
889 <!-- *********************************************************************** -->
891 <a name="knownproblems">Known Problems</a>
893 <!-- *********************************************************************** -->
897 <p>This section contains significant known problems with the LLVM system,
898 listed by component. If you run into a problem, please check the <a
899 href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
900 there isn't already one.</p>
902 <!-- ======================================================================= -->
904 <a name="experimental">Experimental features included with this release</a>
909 <p>The following components of this LLVM release are either untested, known to
910 be broken or unreliable, or are in early development. These components should
911 not be relied on, and bugs should not be filed against them, but they may be
912 useful to some people. In particular, if you would like to work on one of these
913 components, please contact us on the <a
914 href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
917 <li>The Alpha, CellSPU, MicroBlaze, MSP430, MIPS, PTX,
918 and XCore backends are experimental.</li>
919 <li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets
920 other than darwin and ELF X86 systems.</li>
926 <!-- ======================================================================= -->
928 <a name="x86-be">Known problems with the X86 back-end</a>
934 <li>The X86 backend does not yet support
935 all <a href="http://llvm.org/PR879">inline assembly that uses the X86
936 floating point stack</a>. It supports the 'f' and 't' constraints, but not
938 <li>The X86-64 backend does not yet support the LLVM IR instruction
939 <tt>va_arg</tt>. Currently, front-ends support variadic
940 argument constructs on X86-64 by lowering them manually.</li>
941 <li>Windows x64 (aka Win64) code generator has a few issues.
943 <li>llvm-gcc cannot build the mingw-w64 runtime currently
944 due to lack of support for the 'u' inline assembly
945 constraint and for X87 floating point inline assembly.</li>
946 <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt>
947 due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>.
948 It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li>
949 <li>Miss-aligned MOVDQA might crash your program. It is due to
950 <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>,
951 lack of handling aligned internal globals.</li>
959 <!-- ======================================================================= -->
961 <a name="ppc-be">Known problems with the PowerPC back-end</a>
967 <li>The Linux PPC32/ABI support needs testing for the interpreter and static
968 compilation, and lacks support for debug information.</li>
973 <!-- ======================================================================= -->
975 <a name="arm-be">Known problems with the ARM back-end</a>
981 <li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
982 processors, thumb programs can crash or produce wrong
983 results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
984 <li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested.
990 <!-- ======================================================================= -->
992 <a name="sparc-be">Known problems with the SPARC back-end</a>
998 <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not
999 support the 64-bit SPARC ABI (-m64).</li>
1004 <!-- ======================================================================= -->
1006 <a name="mips-be">Known problems with the MIPS back-end</a>
1012 <li>64-bit MIPS targets are not supported yet.</li>
1017 <!-- ======================================================================= -->
1019 <a name="alpha-be">Known problems with the Alpha back-end</a>
1026 <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the
1027 appropriate nops inserted to ensure restartability.</li>
1032 <!-- ======================================================================= -->
1034 <a name="c-be">Known problems with the C back-end</a>
1039 <p>The C backend has numerous problems and is not being actively maintained.
1040 Depending on it for anything serious is not advised.</p>
1043 <li><a href="http://llvm.org/PR802">The C backend has only basic support for
1044 inline assembly code</a>.</li>
1045 <li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common
1046 C++ programs</a>, preventing intermixing between C++ compiled by the CBE and
1047 C++ code compiled with <tt>llc</tt> or native compilers.</li>
1048 <li>The C backend does not support all exception handling constructs.</li>
1049 <li>The C backend does not support arbitrary precision integers.</li>
1055 <!-- ======================================================================= -->
1057 <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a>
1062 <p><b>LLVM 3.0 will be the last release of llvm-gcc.</b></p>
1064 <p>llvm-gcc is generally very stable for the C family of languages. The only
1065 major language feature of GCC not supported by llvm-gcc is the
1066 <tt>__builtin_apply</tt> family of builtins. However, some extensions
1067 are only supported on some targets. For example, trampolines are only
1068 supported on some targets (these are used when you take the address of a
1069 nested function).</p>
1071 <p>Fortran support generally works, but there are still several unresolved bugs
1072 in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the
1073 tools/gfortran component for details. Note that llvm-gcc is missing major
1074 Fortran performance work in the frontend and library that went into GCC after
1075 4.2. If you are interested in Fortran, we recommend that you consider using
1076 <a href="#dragonegg">dragonegg</a> instead.</p>
1078 <p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being
1079 actively maintained. If you are interested in Ada, we recommend that you
1080 consider using <a href="#dragonegg">dragonegg</a> instead.</p>
1085 <!-- *********************************************************************** -->
1087 <a name="additionalinfo">Additional Information</a>
1089 <!-- *********************************************************************** -->
1093 <p>A wide variety of additional information is available on the <a
1094 href="http://llvm.org/">LLVM web page</a>, in particular in the <a
1095 href="http://llvm.org/docs/">documentation</a> section. The web page also
1096 contains versions of the API documentation which is up-to-date with the
1097 Subversion version of the source code.
1098 You can access versions of these documents specific to this release by going
1099 into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p>
1101 <p>If you have any questions or comments about LLVM, please feel free to contact
1102 us via the <a href="http://llvm.org/docs/#maillist"> mailing
1107 <!-- *********************************************************************** -->
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