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| |
| <h1>LLVM 3.0 Release Notes</h1> |
| |
| <img align=right src="http://llvm.org/img/DragonSmall.png" |
| width="136" height="136" alt="LLVM Dragon Logo"> |
| |
| <ol> |
| <li><a href="#intro">Introduction</a></li> |
| <li><a href="#subproj">Sub-project Status Update</a></li> |
| <li><a href="#externalproj">External Projects Using LLVM 3.0</a></li> |
| <li><a href="#whatsnew">What's New in LLVM 3.0?</a></li> |
| <li><a href="GettingStarted.html">Installation Instructions</a></li> |
| <li><a href="#knownproblems">Known Problems</a></li> |
| <li><a href="#additionalinfo">Additional Information</a></li> |
| </ol> |
| |
| <div class="doc_author"> |
| <p>Written by the <a href="http://llvm.org/">LLVM Team</a></p> |
| </div> |
| |
| <!-- |
| <h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.0 |
| release.<br> |
| You may prefer the |
| <a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9 |
| Release Notes</a>.</h1> |
| --> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="intro">Introduction</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| |
| <p>This document contains the release notes for the LLVM Compiler |
| Infrastructure, release 3.0. Here we describe the status of LLVM, including |
| major improvements from the previous release and significant known problems. |
| All LLVM releases may be downloaded from the <a |
| href="http://llvm.org/releases/">LLVM releases web site</a>.</p> |
| |
| <p>For more information about LLVM, including information about the latest |
| release, please check out the <a href="http://llvm.org/">main LLVM |
| web site</a>. If you have questions or comments, the <a |
| href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's |
| Mailing List</a> is a good place to send them.</p> |
| |
| <p>Note that if you are reading this file from a Subversion checkout or the |
| main LLVM web page, this document applies to the <i>next</i> release, not the |
| current one. To see the release notes for a specific release, please see the |
| <a href="http://llvm.org/releases/">releases page</a>.</p> |
| |
| </div> |
| |
| <!-- Features that need text if they're finished for 3.1: |
| ARM EHABI |
| combiner-aa? |
| strong phi elim |
| loop dependence analysis |
| CorrelatedValuePropagation |
| lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1. |
| --> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="subproj">Sub-project Status Update</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| <p> |
| The LLVM 3.0 distribution currently consists of code from the core LLVM |
| repository (which roughly includes the LLVM optimizers, code generators |
| and supporting tools), the Clang repository and the llvm-gcc repository. In |
| addition to this code, the LLVM Project includes other sub-projects that are in |
| development. Here we include updates on these subprojects. |
| </p> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a> |
| </h3> |
| |
| <div> |
| |
| <p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C, |
| C++, and Objective-C languages. Clang aims to provide a better user experience |
| through expressive diagnostics, a high level of conformance to language |
| standards, fast compilation, and low memory use. Like LLVM, Clang provides a |
| modular, library-based architecture that makes it suitable for creating or |
| integrating with other development tools. Clang is considered a |
| production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86 |
| (32- and 64-bit), and for darwin/arm targets.</p> |
| |
| <p>In the LLVM 3.0 time-frame, the Clang team has made many improvements:</p> |
| |
| <p>If Clang rejects your code but another compiler accepts it, please take a |
| look at the <a href="http://clang.llvm.org/compatibility.html">language |
| compatibility</a> guide to make sure this is not intentional or a known issue. |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://dragonegg.llvm.org/">DragonEgg</a> is a |
| <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's |
| optimizers and code generators with LLVM's. |
| Currently it requires a patched version of gcc-4.5. |
| The plugin can target the x86-32 and x86-64 processor families and has been |
| used successfully on the Darwin, FreeBSD and Linux platforms. |
| The Ada, C, C++ and Fortran languages work well. |
| The plugin is capable of compiling plenty of Obj-C, Obj-C++ and Java but it is |
| not known whether the compiled code actually works or not! |
| </p> |
| |
| <p> |
| The 3.0 release has the following notable changes: |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a> |
| </h3> |
| |
| <div> |
| <p> |
| The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a> |
| is a simple library that provides an implementation of the low-level |
| target-specific hooks required by code generation and other runtime components. |
| For example, when compiling for a 32-bit target, converting a double to a 64-bit |
| unsigned integer is compiled into a runtime call to the "__fixunsdfdi" |
| function. The compiler-rt library provides highly optimized implementations of |
| this and other low-level routines (some are 3x faster than the equivalent |
| libgcc routines).</p> |
| |
| <p>In the LLVM 3.0 timeframe,</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="lldb">LLDB: Low Level Debugger</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://lldb.llvm.org/">LLDB</a> is a brand new member of the LLVM |
| umbrella of projects. LLDB is a next generation, high-performance debugger. It |
| is built as a set of reusable components which highly leverage existing |
| libraries in the larger LLVM Project, such as the Clang expression parser, the |
| LLVM disassembler and the LLVM JIT.</p> |
| |
| <p> |
| LLDB is has advanced by leaps and bounds in the 3.0 timeframe. It is |
| dramatically more stable and useful, and includes both a new <a |
| href="http://lldb.llvm.org/tutorial.html">tutorial</a> and a <a |
| href="http://lldb.llvm.org/lldb-gdb.html">side-by-side comparison with |
| GDB</a>.</p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="libc++">libc++: C++ Standard Library</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://libcxx.llvm.org/">libc++</a> is another new member of the LLVM |
| family. It is an implementation of the C++ standard library, written from the |
| ground up to specifically target the forthcoming C++'0X standard and focus on |
| delivering great performance.</p> |
| |
| <p> |
| In the LLVM 3.0 timeframe,</p> |
| |
| <p> |
| Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual |
| licensed</a> under the MIT and UIUC license, allowing it to be used more |
| permissively. |
| </p> |
| |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="LLBrowse">LLBrowse: IR Browser</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://llvm.org/svn/llvm-project/llbrowse/trunk/doc/LLBrowse.html"> |
| LLBrowse</a> is an interactive viewer for LLVM modules. It can load any LLVM |
| module and displays its contents as an expandable tree view, facilitating an |
| easy way to inspect types, functions, global variables, or metadata nodes. It |
| is fully cross-platform, being based on the popular wxWidgets GUI toolkit. |
| </p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="vmkit">VMKit</a> |
| </h3> |
| |
| <div> |
| <p>The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation |
| of a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and |
| just-in-time compilation. As of LLVM 3.0, VMKit now supports generational |
| garbage collectors. The garbage collectors are provided by the MMTk framework, |
| and VMKit can be configured to use one of the numerous implemented collectors |
| of MMTk. |
| </p> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <!-- |
| <h3> |
| <a name="klee">KLEE: A Symbolic Execution Virtual Machine</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://klee.llvm.org/">KLEE</a> is a symbolic execution framework for |
| programs in LLVM bitcode form. KLEE tries to symbolically evaluate "all" paths |
| through the application and records state transitions that lead to fault |
| states. This allows it to construct testcases that lead to faults and can even |
| be used to verify some algorithms. |
| </p> |
| |
| <p>UPDATE!</p> |
| </div>--> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="externalproj">External Open Source Projects Using LLVM 3.0</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| |
| <p>An exciting aspect of LLVM is that it is used as an enabling technology for |
| a lot of other language and tools projects. This section lists some of the |
| projects that have already been updated to work with LLVM 3.0.</p> |
| |
| <!--=========================================================================--> |
| <h3>Crack Programming Language</h3> |
| |
| <div> |
| <p> |
| <a href="http://code.google.com/p/crack-language/">Crack</a> aims to provide the |
| ease of development of a scripting language with the performance of a compiled |
| language. The language derives concepts from C++, Java and Python, incorporating |
| object-oriented programming, operator overloading and strong typing.</p> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <h3>TTA-based Codesign Environment (TCE)</h3> |
| |
| <div> |
| <p>TCE is a toolset for designing application-specific processors (ASP) based on |
| the Transport triggered architecture (TTA). The toolset provides a complete |
| co-design flow from C/C++ programs down to synthesizable VHDL and parallel |
| program binaries. Processor customization points include the register files, |
| function units, supported operations, and the interconnection network.</p> |
| |
| <p>TCE uses Clang and LLVM for C/C++ language support, target independent |
| optimizations and also for parts of code generation. It generates new LLVM-based |
| code generators "on the fly" for the designed TTA processors and loads them in |
| to the compiler backend as runtime libraries to avoid per-target recompilation |
| of larger parts of the compiler chain.</p> |
| </div> |
| |
| |
| |
| <!--=========================================================================--> |
| <h3>PinaVM</h3> |
| |
| <div> |
| <p><a href="http://gitorious.org/pinavm/pages/Home">PinaVM</a> is an open |
| source, <a href="http://www.systemc.org/">SystemC</a> front-end. Unlike many |
| other front-ends, PinaVM actually executes the elaboration of the |
| program analyzed using LLVM's JIT infrastructure. It later enriches the |
| bitcode with SystemC-specific information.</p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3>Pure</h3> |
| |
| <div> |
| <p><a href="http://pure-lang.googlecode.com/">Pure</a> is an |
| algebraic/functional |
| programming language based on term rewriting. Programs are collections |
| of equations which are used to evaluate expressions in a symbolic |
| fashion. The interpreter uses LLVM as a backend to JIT-compile Pure |
| programs to fast native code. Pure offers dynamic typing, eager and lazy |
| evaluation, lexical closures, a hygienic macro system (also based on |
| term rewriting), built-in list and matrix support (including list and |
| matrix comprehensions) and an easy-to-use interface to C and other |
| programming languages (including the ability to load LLVM bitcode |
| modules, and inline C, C++, Fortran and Faust code in Pure programs if |
| the corresponding LLVM-enabled compilers are installed).</p> |
| |
| <p>Pure version 0.47 has been tested and is known to work with LLVM 3.0 |
| (and continues to work with older LLVM releases >= 2.5).</p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3 id="icedtea">IcedTea Java Virtual Machine Implementation</h3> |
| |
| <div> |
| <p> |
| <a href="http://icedtea.classpath.org/wiki/Main_Page">IcedTea</a> provides a |
| harness to build OpenJDK using only free software build tools and to provide |
| replacements for the not-yet free parts of OpenJDK. One of the extensions that |
| IcedTea provides is a new JIT compiler named <a |
| href="http://icedtea.classpath.org/wiki/ZeroSharkFaq">Shark</a> which uses LLVM |
| to provide native code generation without introducing processor-dependent |
| code. |
| </p> |
| |
| <p> OpenJDK 7 b112, IcedTea6 1.9 and IcedTea7 1.13 and later have been tested |
| and are known to work with LLVM 3.0 (and continue to work with older LLVM |
| releases >= 2.6 as well).</p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3>Glasgow Haskell Compiler (GHC)</h3> |
| |
| <div> |
| <p>GHC is an open source, state-of-the-art programming suite for Haskell, |
| a standard lazy functional programming language. It includes an |
| optimizing static compiler generating good code for a variety of |
| platforms, together with an interactive system for convenient, quick |
| development.</p> |
| |
| <p>In addition to the existing C and native code generators, GHC 7.0 now |
| supports an LLVM code generator. GHC supports LLVM 2.7 and later.</p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3>Polly - Polyhedral optimizations for LLVM</h3> |
| |
| <div> |
| <p>Polly is a project that aims to provide advanced memory access optimizations |
| to better take advantage of SIMD units, cache hierarchies, multiple cores or |
| even vector accelerators for LLVM. Built around an abstract mathematical |
| description based on Z-polyhedra, it provides the infrastructure to develop |
| advanced optimizations in LLVM and to connect complex external optimizers. In |
| its first year of existence Polly already provides an exact value-based |
| dependency analysis as well as basic SIMD and OpenMP code generation support. |
| Furthermore, Polly can use PoCC(Pluto) an advanced optimizer for data-locality |
| and parallelism.</p> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3>Rubinius</h3> |
| |
| <div> |
| <p><a href="http://github.com/evanphx/rubinius">Rubinius</a> is an environment |
| for running Ruby code which strives to write as much of the implementation in |
| Ruby as possible. Combined with a bytecode interpreting VM, it uses LLVM to |
| optimize and compile ruby code down to machine code. Techniques such as type |
| feedback, method inlining, and deoptimization are all used to remove dynamism |
| from ruby execution and increase performance.</p> |
| </div> |
| |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="FAUST">FAUST Real-Time Audio Signal Processing Language</a> |
| </h3> |
| |
| <div> |
| <p> |
| <a href="http://faust.grame.fr">FAUST</a> is a compiled language for real-time |
| audio signal processing. The name FAUST stands for Functional AUdio STream. Its |
| programming model combines two approaches: functional programming and block |
| diagram composition. In addition with the C, C++, JAVA output formats, the |
| Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7-3.0.</p> |
| |
| </div> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="whatsnew">What's New in LLVM 3.0?</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| |
| <p>This release includes a huge number of bug fixes, performance tweaks and |
| minor improvements. Some of the major improvements and new features are listed |
| in this section. |
| </p> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="majorfeatures">Major New Features</a> |
| </h3> |
| |
| <div> |
| |
| <p>LLVM 3.0 includes several major new capabilities:</p> |
| |
| <ul> |
| |
| <!-- |
| <li></li> |
| --> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="coreimprovements">LLVM IR and Core Improvements</a> |
| </h3> |
| |
| <div> |
| <p>LLVM IR has several new features for better support of new targets and that |
| expose new optimization opportunities:</p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="optimizer">Optimizer Improvements</a> |
| </h3> |
| |
| <div> |
| |
| <p>In addition to a large array of minor performance tweaks and bug fixes, this |
| release includes a few major enhancements and additions to the optimizers:</p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </li> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="mc">MC Level Improvements</a> |
| </h3> |
| |
| <div> |
| <p> |
| The LLVM Machine Code (aka MC) subsystem was created to solve a number |
| of problems in the realm of assembly, disassembly, object file format handling, |
| and a number of other related areas that CPU instruction-set level tools work |
| in.</p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| |
| <p>For more information, please see the <a |
| href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro to the |
| LLVM MC Project Blog Post</a>. |
| </p> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="codegen">Target Independent Code Generator Improvements</a> |
| </h3> |
| |
| <div> |
| |
| <p>We have put a significant amount of work into the code generator |
| infrastructure, which allows us to implement more aggressive algorithms and make |
| it run faster:</p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="x86">X86-32 and X86-64 Target Improvements</a> |
| </h3> |
| |
| <div> |
| <p>New features and major changes in the X86 target include: |
| </p> |
| |
| <ul> |
| <li>The CRC32 intrinsics have been renamed. The intrinsics were previously |
| @llvm.x86.sse42.crc32.[8|16|32] and @llvm.x86.sse42.crc64.[8|64]. They have |
| been renamed to @llvm.x86.sse42.crc32.32.[8|16|32] and |
| @llvm.x86.sse42.crc32.64.[8|64].</li> |
| |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="ARM">ARM Target Improvements</a> |
| </h3> |
| |
| <div> |
| <p>New features of the ARM target include: |
| </p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="OtherTS">Other Target Specific Improvements</a> |
| </h3> |
| |
| <div> |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="changes">Major Changes and Removed Features</a> |
| </h3> |
| |
| <div> |
| |
| <p>If you're already an LLVM user or developer with out-of-tree changes based |
| on LLVM 2.9, this section lists some "gotchas" that you may run into upgrading |
| from the previous release.</p> |
| |
| <ul> |
| <!-- |
| <li></li> |
| --> |
| </ul> |
| |
| </div> |
| |
| <!--=========================================================================--> |
| <h3> |
| <a name="api_changes">Internal API Changes</a> |
| </h3> |
| |
| <div> |
| |
| <p>In addition, many APIs have changed in this release. Some of the major |
| LLVM API changes are:</p> |
| |
| <ul> |
| <li>The biggest and most pervasive change is that llvm::Type's are no longer |
| returned or accepted as 'const' values. Instead, just pass around non-const |
| Type's.</li> |
| |
| <li><code>PHINode::reserveOperandSpace</code> has been removed. Instead, you |
| must specify how many operands to reserve space for when you create the |
| PHINode, by passing an extra argument into <code>PHINode::Create</code>.</li> |
| |
| <li>PHINodes no longer store their incoming BasicBlocks as operands. Instead, |
| the list of incoming BasicBlocks is stored separately, and can be accessed |
| with new functions <code>PHINode::block_begin</code> |
| and <code>PHINode::block_end</code>.</li> |
| |
| <li>Various functions now take an <code>ArrayRef</code> instead of either a pair |
| of pointers (or iterators) to the beginning and end of a range, or a pointer |
| and a length. Others now return an <code>ArrayRef</code> instead of a |
| reference to a <code>SmallVector</code> or <code>std::vector</code>. These |
| include: |
| <ul> |
| <!-- Please keep this list sorted. --> |
| <li><code>CallInst::Create</code></li> |
| <li><code>ComputeLinearIndex</code> (in <code>llvm/CodeGen/Analysis.h</code>)</li> |
| <li><code>ConstantArray::get</code></li> |
| <li><code>ConstantExpr::getExtractElement</code></li> |
| <li><code>ConstantExpr::getGetElementPtr</code></li> |
| <li><code>ConstantExpr::getInBoundsGetElementPtr</code></li> |
| <li><code>ConstantExpr::getIndices</code></li> |
| <li><code>ConstantExpr::getInsertElement</code></li> |
| <li><code>ConstantExpr::getWithOperands</code></li> |
| <li><code>ConstantFoldCall</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li> |
| <li><code>ConstantFoldInstOperands</code> (in <code>llvm/Analysis/ConstantFolding.h</code>)</li> |
| <li><code>ConstantVector::get</code></li> |
| <li><code>DIBuilder::createComplexVariable</code></li> |
| <li><code>DIBuilder::getOrCreateArray</code></li> |
| <li><code>ExtractValueInst::Create</code></li> |
| <li><code>ExtractValueInst::getIndexedType</code></li> |
| <li><code>ExtractValueInst::getIndices</code></li> |
| <li><code>FindInsertedValue</code> (in <code>llvm/Analysis/ValueTracking.h</code>)</li> |
| <li><code>gep_type_begin</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li> |
| <li><code>gep_type_end</code> (in <code>llvm/Support/GetElementPtrTypeIterator.h</code>)</li> |
| <li><code>IRBuilder::CreateCall</code></li> |
| <li><code>IRBuilder::CreateExtractValue</code></li> |
| <li><code>IRBuilder::CreateInsertValue</code></li> |
| <li><code>IRBuilder::CreateInvoke</code></li> |
| <li><code>InsertValueInst::Create</code></li> |
| <li><code>InsertValueInst::getIndices</code></li> |
| <li><code>InvokeInst::Create</code></li> |
| <li><code>MDNode::get</code></li> |
| <li><code>MDNode::getIfExists</code></li> |
| <li><code>MDNode::getTemporary</code></li> |
| <li><code>MDNode::getWhenValsUnresolved</code></li> |
| <li><code>SimplifyGEPInst</code> (in <code>llvm/Analysis/InstructionSimplify.h</code>)</li> |
| <li><code>TargetData::getIndexedOffset</code></li> |
| </ul></li> |
| |
| <li>All forms of <code>StringMap::getOrCreateValue</code> have been remove |
| except for the one which takes a <code>StringRef</code>.</li> |
| |
| </ul> |
| </div> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="knownproblems">Known Problems</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| |
| <p>This section contains significant known problems with the LLVM system, |
| listed by component. If you run into a problem, please check the <a |
| href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if |
| there isn't already one.</p> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="experimental">Experimental features included with this release</a> |
| </h3> |
| |
| <div> |
| |
| <p>The following components of this LLVM release are either untested, known to |
| be broken or unreliable, or are in early development. These components should |
| not be relied on, and bugs should not be filed against them, but they may be |
| useful to some people. In particular, if you would like to work on one of these |
| components, please contact us on the <a |
| href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p> |
| |
| <ul> |
| <li>The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ |
| and XCore backends are experimental.</li> |
| <li><tt>llc</tt> "<tt>-filetype=obj</tt>" is experimental on all targets |
| other than darwin and ELF X86 systems.</li> |
| |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="x86-be">Known problems with the X86 back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| <li>The X86 backend does not yet support |
| all <a href="http://llvm.org/PR879">inline assembly that uses the X86 |
| floating point stack</a>. It supports the 'f' and 't' constraints, but not |
| 'u'.</li> |
| <li>The X86-64 backend does not yet support the LLVM IR instruction |
| <tt>va_arg</tt>. Currently, front-ends support variadic |
| argument constructs on X86-64 by lowering them manually.</li> |
| <li>Windows x64 (aka Win64) code generator has a few issues. |
| <ul> |
| <li>llvm-gcc cannot build the mingw-w64 runtime currently |
| due to lack of support for the 'u' inline assembly |
| constraint and for X87 floating point inline assembly.</li> |
| <li>On mingw-w64, you will see unresolved symbol <tt>__chkstk</tt> |
| due to <a href="http://llvm.org/bugs/show_bug.cgi?id=8919">Bug 8919</a>. |
| It is fixed in <a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20110321/118499.html">r128206</a>.</li> |
| <li>Miss-aligned MOVDQA might crash your program. It is due to |
| <a href="http://llvm.org/bugs/show_bug.cgi?id=9483">Bug 9483</a>, |
| lack of handling aligned internal globals.</li> |
| </ul> |
| </li> |
| |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="ppc-be">Known problems with the PowerPC back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| <li>The Linux PPC32/ABI support needs testing for the interpreter and static |
| compilation, and lacks support for debug information.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="arm-be">Known problems with the ARM back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| <li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6 |
| processors, thumb programs can crash or produce wrong |
| results (<a href="http://llvm.org/PR1388">PR1388</a>).</li> |
| <li>Compilation for ARM Linux OABI (old ABI) is supported but not fully tested. |
| </li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="sparc-be">Known problems with the SPARC back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| <li>The SPARC backend only supports the 32-bit SPARC ABI (-m32); it does not |
| support the 64-bit SPARC ABI (-m64).</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="mips-be">Known problems with the MIPS back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| <li>64-bit MIPS targets are not supported yet.</li> |
| </ul> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="alpha-be">Known problems with the Alpha back-end</a> |
| </h3> |
| |
| <div> |
| |
| <ul> |
| |
| <li>On 21164s, some rare FP arithmetic sequences which may trap do not have the |
| appropriate nops inserted to ensure restartability.</li> |
| |
| </ul> |
| </div> |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="c-be">Known problems with the C back-end</a> |
| </h3> |
| |
| <div> |
| |
| <p>The C backend has numerous problems and is not being actively maintained. |
| Depending on it for anything serious is not advised.</p> |
| |
| <ul> |
| <li><a href="http://llvm.org/PR802">The C backend has only basic support for |
| inline assembly code</a>.</li> |
| <li><a href="http://llvm.org/PR1658">The C backend violates the ABI of common |
| C++ programs</a>, preventing intermixing between C++ compiled by the CBE and |
| C++ code compiled with <tt>llc</tt> or native compilers.</li> |
| <li>The C backend does not support all exception handling constructs.</li> |
| <li>The C backend does not support arbitrary precision integers.</li> |
| </ul> |
| |
| </div> |
| |
| |
| <!-- ======================================================================= --> |
| <h3> |
| <a name="llvm-gcc">Known problems with the llvm-gcc front-end</a> |
| </h3> |
| |
| <div> |
| |
| <p><b>LLVM 3.0 will be the last release of llvm-gcc.</b></p> |
| |
| <p>llvm-gcc is generally very stable for the C family of languages. The only |
| major language feature of GCC not supported by llvm-gcc is the |
| <tt>__builtin_apply</tt> family of builtins. However, some extensions |
| are only supported on some targets. For example, trampolines are only |
| supported on some targets (these are used when you take the address of a |
| nested function).</p> |
| |
| <p>Fortran support generally works, but there are still several unresolved bugs |
| in <a href="http://llvm.org/bugs/">Bugzilla</a>. Please see the |
| tools/gfortran component for details. Note that llvm-gcc is missing major |
| Fortran performance work in the frontend and library that went into GCC after |
| 4.2. If you are interested in Fortran, we recommend that you consider using |
| <a href="#dragonegg">dragonegg</a> instead.</p> |
| |
| <p>The llvm-gcc 4.2 Ada compiler has basic functionality, but is no longer being |
| actively maintained. If you are interested in Ada, we recommend that you |
| consider using <a href="#dragonegg">dragonegg</a> instead.</p> |
| </div> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <h2> |
| <a name="additionalinfo">Additional Information</a> |
| </h2> |
| <!-- *********************************************************************** --> |
| |
| <div> |
| |
| <p>A wide variety of additional information is available on the <a |
| href="http://llvm.org/">LLVM web page</a>, in particular in the <a |
| href="http://llvm.org/docs/">documentation</a> section. The web page also |
| contains versions of the API documentation which is up-to-date with the |
| Subversion version of the source code. |
| You can access versions of these documents specific to this release by going |
| into the "<tt>llvm/doc/</tt>" directory in the LLVM tree.</p> |
| |
| <p>If you have any questions or comments about LLVM, please feel free to contact |
| us via the <a href="http://llvm.org/docs/#maillist"> mailing |
| lists</a>.</p> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| |
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