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873 lines
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 2.5 Release Notes</title>
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</head>
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<body>
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<div class="doc_title">LLVM 2.5 Release Notes</div>
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<ol>
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<li><a href="#intro">Introduction</a></li>
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<li><a href="#subproj">Sub-project Status Update</a></li>
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<li><a href="#externalproj">External Projects Using LLVM 2.5</a></li>
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<li><a href="#whatsnew">What's New in LLVM?</a></li>
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<li><a href="GettingStarted.html">Installation Instructions</a></li>
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<li><a href="#portability">Portability and Supported Platforms</a></li>
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<li><a href="#knownproblems">Known Problems</a></li>
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<li><a href="#additionalinfo">Additional Information</a></li>
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</ol>
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<div class="doc_author">
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<p>Written by the <a href="http://llvm.org">LLVM Team</a></p>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="intro">Introduction</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This document contains the release notes for the LLVM Compiler
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Infrastructure, release 2.5. Here we describe the status of LLVM, including
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major improvements from the previous release and significant known problems.
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All LLVM releases may be downloaded from the <a
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href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
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<p>For more information about LLVM, including information about the latest
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release, please check out the <a href="http://llvm.org/">main LLVM
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web site</a>. If you have questions or comments, the <a
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href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developer's Mailing
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List</a> is a good place to send them.</p>
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<p>Note that if you are reading this file from a Subversion checkout or the
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main LLVM web page, this document applies to the <i>next</i> release, not the
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current one. To see the release notes for a specific release, please see the
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<a href="http://llvm.org/releases/">releases page</a>.</p>
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</div>
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<!-- Unfinished features in 2.5:
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Machine LICM
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Machine Sinking
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target-specific intrinsics
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gold lto plugin
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pre-alloc splitter, strong phi elim
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llc -enable-value-prop, propagation of value info (sign/zero ext info) from
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one MBB to another
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debug info for optimized code
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interpreter + libffi
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postalloc scheduler: anti dependence breaking, hazard recognizer?
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-->
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<!-- for announcement email:
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-->
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="subproj">Sub-project Status Update</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>
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The LLVM 2.5 distribution currently consists of code from the core LLVM
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repository (which roughly includes the LLVM optimizers, code generators and
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supporting tools) and the llvm-gcc repository. In addition to this code, the
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LLVM Project includes other sub-projects that are in development. The two which
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are the most actively developed are the <a href="#clang">Clang Project</a> and
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the <a href="#vmkit">VMKit Project</a>.
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</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
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</div>
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<div class="doc_text">
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<p>The <a href="http://clang.llvm.org/">Clang project</a> is an effort to build
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a set of new 'LLVM native' front-end technologies for the LLVM optimizer
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and code generator. While Clang is not included in the LLVM 2.5 release, it
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is continuing to make major strides forward in all areas. Its C and Objective-C
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parsing and code generation support is now very solid. For example, it is
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capable of successfully building many real applications for X86-32 and X86-64,
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including <a href="http://wiki.freebsd.org/BuildingFreeBSDWithClang">the FreeBSD
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kernel</a>. C++ is also making <a
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href="http://clang.llvm.org/cxx_status.html">incredible progress</a>, and work
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on templates has recently started.</p>
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<p>While Clang is not yet production quality, it is progressing very nicely and
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is quite usable for building many C and Objective-C applications. If you are
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interested in fast compiles and good diagnostics, we encourage you to try it out
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by <a href="http://clang.llvm.org/get_started.html">building from mainline</a>
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and reporting any issues you hit to the <a
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href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">Clang front-end mailing
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list</a>.</p>
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<p>In the LLVM 2.5 time-frame, the Clang team has made many improvements:</p>
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<ul>
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<li>Clang now has a new driver, which is focused on providing a GCC-compatible
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interface.</li>
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<li>The X86-64 ABI is now supported.</li>
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<li>Precompiled header support is now implemented.</li>
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<li>Objective-C support is significantly improved beyond LLVM 2.4, supporting
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many features, such as Objective-C Garbage Collection.</li>
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<li>Many many bugs are fixed.</li>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="clangsa">Clang Static Analyzer</a>
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</div>
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<div class="doc_text">
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<p>Previously announced in the last LLVM release, the Clang project also
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includes an early stage static source code analysis tool for <a
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href="http://clang.llvm.org/StaticAnalysis.html">automatically finding bugs</a>
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in C and Objective-C programs. The tool performs a growing set of checks to find
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bugs that occur on a specific path within a program.</p>
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<p>In the LLVM 2.5 time-frame there have been many significant improvements to
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the analyzer's core path simulation engine and machinery for generating
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path-based bug reports to end-users. Particularly noteworthy improvements
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include experimental support for full field-sensitivity and reasoning about heap
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objects as well as an improved value-constraints subengine that does a much
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better job of reasoning about inequality relationships (e.g., <tt>x > 2</tt>)
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between variables and constants.
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<p>The set of checks performed by the static analyzer continue to expand, and
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future plans for the tool include full source-level inter-procedural analysis
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and deeper checks such as buffer overrun detection. There are many opportunities
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to extend and enhance the static analyzer, and anyone interested in working on
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this project is encouraged to get involved!</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
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</div>
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<div class="doc_text">
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<p>
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The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
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a JVM and a CLI Virtual Machines (Microsoft .NET is an
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implementation of the CLI) using the Just-In-Time compiler of LLVM.</p>
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<p>Following LLVM 2.5, VMKit has its first release ? that you can find on its
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<a href="http://vmkit.llvm.org/releases/">webpage</a>. The release includes
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bug fixes, cleanup and new features. The major changes are:</p>
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<ul>
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<li>Ahead of Time compiler: compiles .class files to llvm .bc. VMKit uses this
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functionality to native compile the standard classes (eg java.lang.String).
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Users can compile AOT .class files into dynamic libraries and run them with the
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help of VMKit.</li>
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<li>New exception model: the dwarf exception model is very slow for
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exception-intensive applications, so the JVM has had a new implementation of
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exceptions which check at each function call if an exception happened. There is
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a low performance penalty on applications without exceptions, but it is a big
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gain for exception-intensive applications. For example the jack benchmark in
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Spec JVM98 is 6x faster (performance gain of 83%).</li>
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<li>New support for OSX/X64, Linux/X64 (with the Boehm GC), Linux/ppc32.</li>
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</ul>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="externalproj">External Projects Using LLVM 2.5</a>
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</div>
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<!-- *********************************************************************** -->
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="pure">Pure</a>
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</div>
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<div class="doc_text">
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<p>
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http://pure-lang.googlecode.com/
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</p>
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<p>
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Pure is an algebraic/functional programming language based on term rewriting.
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Programs are collections of equations which are used to evaluate expressions in
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a symbolic fashion. Pure offers dynamic typing, eager and lazy evaluation,
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lexical closures, a hygienic macro system (also based on term rewriting),
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built-in list and matrix support (including list and matrix comprehensions) and
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an easy-to-use C interface. The interpreter uses LLVM as a backend to
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JIT-compile Pure programs to fast native code.</p>
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<p>In addition to the usual algebraic data structures, Pure also has
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MATLAB-style matrices in order to support numeric computations and signal
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processing in an efficient way. Pure is mainly aimed at mathematical
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applications right now, but it has been designed as a general purpose language.
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The dynamic interpreter environment and the C interface make it possible to use
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it as a kind of functional scripting language for many application areas.
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</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="ldc">LLVM D Compiler</a>
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</div>
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<div class="doc_text">
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<p>
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http://www.dsource.org/projects/ldc
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</p>
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<p>
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I'd like to inform that the LDC project (LLVM D
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Compiler) is working with release 2.5 of LLVM. In fact we've required
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2.5 in our trunk since the release was branched.
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The improvements in 2.5 have fixed a lot of problems with LDC, more
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specifically the new inline asm constraints, better debug info
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support, general bugfixes :) and better x86-64 support have allowed
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some major improvements in LDC, getting us much closer to being as
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fully featured as the original DMD compiler from DigitalMars.
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</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="RoadsendPHP">Roadsend PHP</a>
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</div>
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<div class="doc_text">
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<p>http://code.roadsend.com/rphp</p>
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<p>Roadsend PHP is using LLVM for code generation. This is an open source
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project.
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</p>
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</div>
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|
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<!-- *********************************************************************** -->
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<div class="doc_section">
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<a name="whatsnew">What's New in LLVM?</a>
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</div>
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<!-- *********************************************************************** -->
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<div class="doc_text">
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<p>This release includes a huge number of bug fixes, performance tweaks, and
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minor improvements. Some of the major improvements and new features are listed
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in this section.
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</p>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="majorfeatures">Major New Features</a>
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</div>
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<div class="doc_text">
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<p>LLVM 2.5 includes several major new capabilities:</p>
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<ul>
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<li><p>The code generator now supports arbitrary precision integers.
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Types like <tt>i33</tt> have long been valid in the LLVM IR, but previously
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could only be used with the interpreter.
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Now IR using such types can be compiled to native code on all targets.
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All operations are supported if the integer is not bigger than twice the
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target machine word size.
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Simple operations like loads, stores and shifts by a constant amount are
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supported for integers of any size.
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</p></li>
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<!--
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Random stuff:
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Pure project: http://code.google.com/p/pure-lang/
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xcore backend!
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fortran on darwin!
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.ll parser rewrite, caret diags, better errors, less fragile (less likely to
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crash on strange things). No longer depends on flex/bison.
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GCC inliner off, llvm handles always-inline.
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cmake mature?
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x86 backend GS segment -> addr space 256 (r62980)
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nocapture
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memdep (used by GVN and memcpyopt) is faster / more aggressive.
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how to write a backend doc docs/WritingAnLLVMBackend.html
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fastisel + exception handling
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vector widening <3 x float> -> <4 x float>
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arm port improvements? arm jit encoding stuff, constant island support?
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JIT TLS support on x86-32 but not x86-64.
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mem2reg now faster on code with huge basic blocks
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stack protectors/stack canaries, -fstack-protector, controllable on a
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per-function basis with attributes.
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shufflevector is generalized to allow different shuffle mask width than its
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input vectors.
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loop optimizer improves floating point induction variables
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llvm/Analysis/DebugInfo.h classes, llvm-gcc and clang and codegen use them.
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DebugInfoBuilder gone.
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asmprinters seperate from targets for jits
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PBQP register allocator now supports register coalescing.
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JIT supports exceptions on linux/x86-64 and linux/x86-64.
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integer overflow intrinsics for [us](add/sub/mul). Supported on all targets,
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but only generates efficient code on x86.
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X86 backend now supports -disable-mmx.
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noalias attribute on return value indicates that function returns new memory
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(e.g. malloc).
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llvmc2 renamed to llvmc
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Jump threading more powerful: it is iterative, handles threading based on values
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with fully redundant and partially redundant loads.
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LSR improvements?
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ARM debug info support?
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unit test framework based on Google Test.
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vector shift support + X86 backend.
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x86 JIT now detects core i7 and atom, autoconfiguring itself appropriately.
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SROA is more aggressive about promoting unions.
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non-zero __builtin_return_address values on X86.
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x86-64 now uses red zone (unless -mno-red-zone option is specified).
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private linkage.
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llvm-gcc defaults to -fno-math-errno on all x86 targets.
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initial support for debug line numbers when optimization enabled, not useful in
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2.5 but will be for 2.6.
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-->
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
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</div>
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<div class="doc_text">
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<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
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front-ends and driver with the LLVM optimizer and code generator. It currently
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includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
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<ul>
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<li>?</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="coreimprovements">LLVM Core Improvements</a>
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</div>
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<div class="doc_text">
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<p>New features include:</p>
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<ul>
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<li>?</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="optimizer">Optimizer Improvements</a>
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</div>
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<div class="doc_text">
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<p>In addition to a huge array of bug fixes and minor performance tweaks, this
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release includes a few major enhancements and additions to the optimizers:</p>
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<ul>
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<li>?</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="codegen">Code Generator Improvements</a>
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</div>
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<div class="doc_text">
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<p>We have put a significant amount of work into the code generator infrastructure,
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which allows us to implement more aggressive algorithms and make it run
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faster:</p>
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<ul>
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<li>The type legalization logic has been completely rewritten, and is now
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more powerful (it supports arbitrary precision integer types for example)
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and hopefully more correct.
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The type legalizer converts operations on types that are not natively
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supported by the target machine into equivalent code sequences that only use
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natively supported types.
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The old type legalizer is still available and will be used if
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<tt>-disable-legalize-types</tt> is passed to <tt>llc</tt>.
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</li>
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<li>?</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="pic16">PIC16 Target Improvements</a>
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</div>
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<div class="doc_text">
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<p>New features of the PIC16 target include:
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</p>
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<ul>
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<li>Both direct and indirect load/stores work now.</li>
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<li>Logical, bitwise and conditional operations now work for integer data
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types.</li>
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<li>Function calls involving basic types work now.</li>
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<li>Support for integer arrays.</li>
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<li>Compiler can now emit libcalls for operations not support by m/c insns.</li>
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<li>Support for both data and rom address spaces.</li>
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</li>
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</ul>
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<p>Things not yet supported:</p>
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<ul>
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<li>Floating point.</li>
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<li>Passing/returning aggregate types to/from functions.</li>
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<li>Variable arguments.</li>
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<li>Indirect function calls.</li>
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<li>Interrupts/prgrams.</li>
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<li>Debug info.</li>
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</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="othertargetspecific">Other Target Specific Improvements</a>
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</div>
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<div class="doc_text">
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<p>New target-specific features include:
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</p>
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|
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<ul>
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<li>?</li>
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</ul>
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</div>
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|
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="otherimprovements">Other Improvements</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
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<p>New features include:
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</p>
|
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|
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<ul>
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<li>?</li>
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</ul>
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</div>
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<!--=========================================================================-->
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<div class="doc_subsection">
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<a name="changes">Major Changes and Removed Features</a>
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</div>
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|
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<div class="doc_text">
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|
|
<p>If you're already an LLVM user or developer with out-of-tree changes based
|
|
on LLVM 2.4, this section lists some "gotchas" that you may run into upgrading
|
|
from the previous release.</p>
|
|
|
|
<ul>
|
|
|
|
<li>?</li>
|
|
</ul>
|
|
|
|
|
|
<p>In addition, many APIs have changed in this release. Some of the major LLVM
|
|
API changes are:</p>
|
|
|
|
<ul>
|
|
<li>?</li>
|
|
</ul>
|
|
|
|
<li>?</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="portability">Portability and Supported Platforms</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>LLVM is known to work on the following platforms:</p>
|
|
|
|
<ul>
|
|
<li>Intel and AMD machines (IA32, X86-64, AMD64, EMT-64) running Red Hat
|
|
Linux, Fedora Core and FreeBSD (and probably other unix-like systems).</li>
|
|
<li>PowerPC and X86-based Mac OS X systems, running 10.3 and above in 32-bit
|
|
and 64-bit modes.</li>
|
|
<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
|
|
<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
|
|
support is available for native builds with Visual C++).</li>
|
|
<li>Sun UltraSPARC workstations running Solaris 10.</li>
|
|
<li>Alpha-based machines running Debian GNU/Linux.</li>
|
|
<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
|
|
</ul>
|
|
|
|
<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
|
|
to the machine and operating system on which it is built. However, minor
|
|
porting may be required to get LLVM to work on new platforms. We welcome your
|
|
portability patches and reports of successful builds or error messages.</p>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="knownproblems">Known Problems</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<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>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="experimental">Experimental features included with this release</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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 MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
|
|
<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
|
|
value for this option.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="x86-be">Known problems with the X86 back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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 backend generates inefficient floating point code when configured
|
|
to generate code for systems that don't have SSE2.</li>
|
|
<li>Win64 code generation wasn't widely tested. Everything should work, but we
|
|
expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
|
|
currently due
|
|
to <a href="http://llvm.org/PR2255">several</a>
|
|
<a href="http://llvm.org/PR2257">bugs</a> due to lack of support for the
|
|
'u' inline assembly constraint and X87 floating point inline assembly.</li>
|
|
<li>The X86-64 backend does not yet support the LLVM IR instruction
|
|
<tt>va_arg</tt>. Currently, the llvm-gcc front-end supports variadic
|
|
argument constructs on X86-64 by lowering them manually.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ppc-be">Known problems with the PowerPC back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The Linux PPC32/ABI support needs testing for the interpreter and static
|
|
compilation, and lacks support for debug information.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="arm-be">Known problems with the ARM back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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>
|
|
<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly
|
|
execute
|
|
programs compiled with LLVM. Please use more recent versions of QEMU.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="sparc-be">Known problems with the SPARC back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="mips-be">Known problems with the MIPS back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The O32 ABI is not fully supported.</li>
|
|
<li>64-bit MIPS targets are not supported yet.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="alpha-be">Known problems with the Alpha back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ia64-be">Known problems with the IA64 back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ul>
|
|
<li>The Itanium backend is highly experimental, and has a number of known
|
|
issues. We are looking for a maintainer for the Itanium backend. If you
|
|
are interested, please contact the LLVMdev mailing list.</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c-be">Known problems with the C back-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<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 llc 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>
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c-fe">Known problems with the llvm-gcc C front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>llvm-gcc does not currently support <a href="http://llvm.org/PR869">Link-Time
|
|
Optimization</a> on most platforms "out-of-the-box". Please inquire on the
|
|
LLVMdev mailing list if you are interested.</p>
|
|
|
|
<p>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>If you run into GCC extensions which are not supported, please let us know.
|
|
</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>The C++ front-end is considered to be fully
|
|
tested and works for a number of non-trivial programs, including LLVM
|
|
itself, Qt, Mozilla, etc.</p>
|
|
|
|
<ul>
|
|
<li>Exception handling works well on the X86 and PowerPC targets. Currently
|
|
only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
|
|
</ul>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
<ul>
|
|
<li>Fortran support generally works, but there are still several unresolved bugs
|
|
in Bugzilla. Please see the tools/gfortran component for details.</li>
|
|
|
|
<li>The Fortran front-end currently does not build on Darwin (without tweaks)
|
|
due to unresolved dependencies on the C front-end.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature
|
|
technology and problems should be expected.
|
|
<ul>
|
|
<li>The Ada front-end currently only builds on X86-32. This is mainly due
|
|
to lack of trampoline support (pointers to nested functions) on other platforms,
|
|
however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
|
|
which does support trampolines.</li>
|
|
<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
|
|
This is due to lack of LLVM support for <tt>setjmp</tt>/<tt>longjmp</tt> style
|
|
exception handling, which is used internally by the compiler.
|
|
Workaround: configure with --disable-bootstrap.</li>
|
|
<li>The c380004, <a href="http://llvm.org/PR2010">c393010</a>
|
|
and <a href="http://llvm.org/PR2421">cxg2021</a> ACATS tests fail
|
|
(c380004 also fails with gcc-4.2 mainline).
|
|
If the compiler is built with checks disabled then <a href="http://llvm.org/PR2010">c393010</a>
|
|
causes the compiler to go into an infinite loop, using up all system memory.</li>
|
|
<li>Some gcc specific Ada tests continue to crash the compiler.</li>
|
|
<li>The -E binder option (exception backtraces)
|
|
<a href="http://llvm.org/PR1982">does not work</a> and will result in programs
|
|
crashing if an exception is raised. Workaround: do not use -E.</li>
|
|
<li>Only discrete types <a href="http://llvm.org/PR1981">are allowed to start
|
|
or finish at a non-byte offset</a> in a record. Workaround: do not pack records
|
|
or use representation clauses that result in a field of a non-discrete type
|
|
starting or finishing in the middle of a byte.</li>
|
|
<li>The <tt>lli</tt> interpreter <a href="http://llvm.org/PR2009">considers
|
|
'main' as generated by the Ada binder to be invalid</a>.
|
|
Workaround: hand edit the file to use pointers for <tt>argv</tt> and
|
|
<tt>envp</tt> rather than integers.</li>
|
|
<li>The <tt>-fstack-check</tt> option <a href="http://llvm.org/PR2008">is
|
|
ignored</a>.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="additionalinfo">Additional Information</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<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>
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
<hr>
|
|
<address>
|
|
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
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<a href="http://validator.w3.org/check/referer"><img
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src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
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|
|
<a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
|
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Last modified: $Date$
|
|
</address>
|
|
|
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</body>
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</html>
|