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	1. pointer-vector 2. type legalizer changes and vector-select 3. X86 ISA changes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146964 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
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			529 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 3.1 Release Notes</title>
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| </head>
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| <body>
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| 
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| <h1>LLVM 3.1 Release Notes</h1>
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| 
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| <div>
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| <img style="float:right" src="http://llvm.org/img/DragonSmall.png"
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|      width="136" height="136" alt="LLVM Dragon Logo">
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| </div>
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| 
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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 3.1</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="#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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| 
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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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| <h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.1
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| release.<br>
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| You may prefer the
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| <a href="http://llvm.org/releases/3.0/docs/ReleaseNotes.html">LLVM 3.0
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| Release Notes</a>.</h1>
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| 
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| <!-- *********************************************************************** -->
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| <h2>
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|   <a name="intro">Introduction</a>
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| </h2>
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| <!-- *********************************************************************** -->
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| 
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| <div>
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| 
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| <p>This document contains the release notes for the LLVM Compiler
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|    Infrastructure, release 3.1.  Here we describe the status of LLVM, including
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|    major improvements from the previous release, improvements in various
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|    subprojects of LLVM, and some of the current users of the code.
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|    All LLVM releases may be downloaded from
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|    the <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
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| 
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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 web
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|    site</a>.  If you have questions or comments,
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|    the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM
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|    Developer's Mailing List</a> is a good place to send them.</p>
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| 
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| <p>Note that if you are reading this file from a Subversion checkout or the main
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|    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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| 
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| </div>
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| 
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| 
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| <!-- *********************************************************************** -->
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| <h2>
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|   <a name="subproj">Sub-project Status Update</a>
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| </h2>
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| <!-- *********************************************************************** -->
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| 
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| <div>
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| 
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| <p>The LLVM 3.1 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 Clang repository.  In
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|    addition to this code, the LLVM Project includes other sub-projects that are
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|    in development.  Here we include updates on these subprojects.</p>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="clang">Clang: C/C++/Objective-C Frontend Toolkit</a>
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| </h3>
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| 
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| <div>
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| 
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| <p><a href="http://clang.llvm.org/">Clang</a> is an LLVM front end for the C,
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|    C++, and Objective-C languages. Clang aims to provide a better user
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|    experience through expressive diagnostics, a high level of conformance to
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|    language standards, fast compilation, and low memory use. Like LLVM, Clang
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|    provides a modular, library-based architecture that makes it suitable for
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|    creating or integrating with other development tools. Clang is considered a
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|    production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
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|    (32- and 64-bit), and for Darwin/ARM targets.</p>
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| 
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| <p>In the LLVM 3.1 time-frame, the Clang team has made many improvements:</p>
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| <ul>
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|   <li>...</li>
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| </ul>
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| 
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|   <p>For more details about the changes to Clang since the 2.9 release, see the
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| <a href="http://clang.llvm.org/docs/ReleaseNotes.html">Clang release notes</a>
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| </p>
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| 
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| 
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| <p>If Clang rejects your code but another compiler accepts it, please take a
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|    look at the <a href="http://clang.llvm.org/compatibility.html">language
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|    compatibility</a> guide to make sure this is not intentional or a known
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|    issue.</p>
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| 
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| </div>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="dragonegg">DragonEgg: GCC front-ends, LLVM back-end</a>
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| </h3>
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| 
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| <div>
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| <p><a href="http://dragonegg.llvm.org/">DragonEgg</a> is a
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|    <a href="http://gcc.gnu.org/wiki/plugins">gcc plugin</a> that replaces GCC's
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|    optimizers and code generators with LLVM's. It works with gcc-4.5 or gcc-4.6,
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|    targets the x86-32 and x86-64 processor families, and has been successfully
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|    used on the Darwin, FreeBSD, KFreeBSD, Linux and OpenBSD platforms.  It fully
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|    supports Ada, C, C++ and Fortran.  It has partial support for Go, Java, Obj-C
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|    and Obj-C++.</p>
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| 
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| <p>The 3.1 release has the following notable changes:</p>
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| 
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|   <ul>
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| 
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|   <li>...</li>
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| 
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| </ul>
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| 
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| </div>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="compiler-rt">compiler-rt: Compiler Runtime Library</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>The new LLVM <a href="http://compiler-rt.llvm.org/">compiler-rt project</a>
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|    is a simple library that provides an implementation of the low-level
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|    target-specific hooks required by code generation and other runtime
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|    components.  For example, when compiling for a 32-bit target, converting a
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|    double to a 64-bit unsigned integer is compiled into a runtime call to the
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|    "__fixunsdfdi" function. The compiler-rt library provides highly optimized
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|    implementations of this and other low-level routines (some are 3x faster than
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|    the equivalent libgcc routines).</p>
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| 
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| <p>....</p>
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| 
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| </div>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="lldb">LLDB: Low Level Debugger</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>LLDB is a ground-up implementation of a command line debugger, as well as a
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|    debugger API that can be used from other applications.  LLDB makes use of the
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|    Clang parser to provide high-fidelity expression parsing (particularly for
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|    C++) and uses the LLVM JIT for target support.</p>
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| 
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| <p>...</p>
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| 
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| </div>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="libc++">libc++: C++ Standard Library</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>Like compiler_rt, libc++ is now <a href="DeveloperPolicy.html#license">dual
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|    licensed</a> under the MIT and UIUC license, allowing it to be used more
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|    permissively.</p>
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| 
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| <p>...</p>
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| 
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| </div>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="vmkit">VMKit</a>
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| </h3>
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| 
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| <div>
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| 
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|   <p>The <a href="http://vmkit.llvm.org/">VMKit project</a> is an
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|   implementation of a Java Virtual Machine (Java VM or JVM) that uses LLVM for
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|   static and just-in-time compilation.
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| 
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|   <p>In the LLVM 3.1 time-frame, VMKit has had significant improvements on both
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|   runtime and startup performance:</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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| 
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| </div>
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| 
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| </div>
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| 
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| <!-- *********************************************************************** -->
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| <h2>
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|   <a name="externalproj">External Open Source Projects Using LLVM 3.1</a>
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| </h2>
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| <!-- *********************************************************************** -->
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| 
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| <div>
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| 
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| <p>An exciting aspect of LLVM is that it is used as an enabling technology for
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|    a lot of other language and tools projects.  This section lists some of the
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|    projects that have already been updated to work with LLVM 3.1.</p>
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| 
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|   ... to be filled in right before the release ...
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| 
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| </div>
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| 
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| <!-- *********************************************************************** -->
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| <h2>
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|   <a name="whatsnew">What's New in LLVM 3.1?</a>
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| </h2>
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| <!-- *********************************************************************** -->
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| 
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| <div>
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| 
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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
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|    listed in this section.</p>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="majorfeatures">Major New Features</a>
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| </h3>
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| 
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| <div>
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| 
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|   <!-- Features that need text if they're finished for 3.1:
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|    ARM EHABI
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|    combiner-aa?
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|    strong phi elim
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|    loop dependence analysis
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|    CorrelatedValuePropagation
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|    lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.1.
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|    Integrated assembler on by default for arm/thumb?
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| 
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|    -->
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| 
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|   <!-- Near dead:
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|    Analysis/RegionInfo.h + Dom Frontiers
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|    SparseBitVector: used in LiveVar.
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|    llvm/lib/Archive - replace with lib object?
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|    -->
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| 
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| <p>LLVM 3.1 includes several major changes and big features:</p>
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| 
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| <ul>
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|   <li><a href="../tools/clang/docs/AddressSanitizer.html">AddressSanitizer</a>,
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|       a fast memory error detector.</li>
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|   <li><a href="CodeGenerator.html#machineinstrbundle">MachineInstr Bundles</a>,
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|       Support to model instruction bundling / packing.</li>
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|   <li>....</li>
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| </ul>
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| 
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| </div>
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| 
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="coreimprovements">LLVM IR and Core Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>LLVM IR has several new features for better support of new targets and that
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|    expose new optimization opportunities:</p>
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| 
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|   <ul>
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|     <li>IR support for half float</li>
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| 	<li>IR support for vectors of pointers, including vector GEPs.</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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| <h3>
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| <a name="optimizer">Optimizer Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>In addition to many minor performance tweaks and bug fixes, this
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|    release includes a few major enhancements and additions to the
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|    optimizers:</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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| 
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| </div>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="mc">MC Level Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>The LLVM Machine Code (aka MC) subsystem was created to solve a number of
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|    problems in the realm of assembly, disassembly, object file format handling,
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|    and a number of other related areas that CPU instruction-set level tools work
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|    in. For more information, please see
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|   the <a href="http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html">Intro
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|     to the LLVM MC Project Blog Post</a>.</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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| 
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| </div>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="codegen">Target Independent Code Generator Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>We have changed the way that the Type Legalizer legalizes vectors.
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| 	The type legalizer now attempts to promote integer elements.
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| 	This enabled the implementation of vector-select.
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| 	Additionally, we see a performance boost on workloads which use vectors of chars and shorts, since they are now promoted
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| 	to 32-bit types, which are better supported by the SIMD instruction set.
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| 	Floating point types are still widened as before.</p>
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| 
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| 
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| <p>We have put a significant amount of work into the code generator
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|    infrastructure, which allows us to implement more aggressive algorithms and
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|    make it run faster:</p>
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| 
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| <ul>
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|   <li>TableGen can now synthesize register classes that are only needed to
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|   represent combinations of constraints from instructions and sub-registers.
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|   The synthetic register classes inherit most of their properties form their
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|   closest user-defined super-class.</li>
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| </ul>
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| </div>
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="x86">X86-32 and X86-64 Target Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>New features and major changes in the X86 target include:</p>
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| 
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| <ul>
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|   <li>Bug fixes and improved support for AVX1</li>
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|   <li>Support for AVX2 (still incomplete at this point)</li>
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|   <li>....</li>
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| </ul>
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| 
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| </div>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="ARM">ARM Target Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>New features of the ARM target include:</p>
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| 
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| <ul>
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|   <li>The constant island pass now supports basic block and constant pool entry
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|   alignments greater than 4 bytes.</li> </ul>
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| </div>
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| 
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| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="MIPS">MIPS Target Improvements</a>
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| </h3>
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| 
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| <div>
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| 
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| <p>This release has seen major new work on just about every aspect of the MIPS
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|   backend.  Some of the major new features include:</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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| <h3>
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| <a name="OtherTS">Other Target Specific Improvements</a>
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| </h3>
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| 
 | |
| <div>
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| 
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| <ul>
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|   <li>....</li>
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| 
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| 
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| </ul>
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| 
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| </div>
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| 
 | |
| <!--=========================================================================-->
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| <h3>
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| <a name="changes">Major Changes and Removed Features</a>
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| </h3>
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| 
 | |
| <div>
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| 
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| <p>If you're already an LLVM user or developer with out-of-tree changes based on
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|    LLVM 3.1, this section lists some "gotchas" that you may run into upgrading
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|    from the previous release.</p>
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| 
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| <ul>
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| <li>LLVM 3.1 removes support for reading LLVM 2.9 bitcode files.  Going forward,
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|     we aim for all future versions of LLVM to read bitcode files and .ll files
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|     produced by LLVM 3.0 and later.</li>
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|   <li>....</li>
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| </ul>
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| 
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| </div>
 | |
| 
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| <!--=========================================================================-->
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| <h3>
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| <a name="api_changes">Internal API Changes</a>
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| </h3>
 | |
| 
 | |
| <div>
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| 
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| <p>In addition, many APIs have changed in this release.  Some of the major
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|    LLVM API changes are:</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>
 | |
| 
 | |
| </div>
 | |
| 
 | |
| <!-- *********************************************************************** -->
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| <h2>
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|   <a name="knownproblems">Known Problems</a>
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| </h2>
 | |
| <!-- *********************************************************************** -->
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| 
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| <div>
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| 
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| <p>LLVM is generally a production quality compiler, and is used by a broad range
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|    of applications and shipping in many products.  That said, not every
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|    subsystem is as mature as the aggregate, particularly the more obscure
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|    targets.  If you run into a problem, please check the <a
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|    href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
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|    there isn't already one or ask on the <a
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|     href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev
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|     list</a>.</p>
 | |
| 
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|   <p>Known problem areas include:</p>
 | |
| 
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| <ul>
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|   <li>The Alpha, Blackfin, CellSPU, MSP430, PTX, SystemZ and
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|       XCore backends are experimental, and the Alpha, Blackfin and SystemZ
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|       targets have already been removed from mainline.</li>
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| 
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|   <li>The integrated assembler, disassembler, and JIT is not supported by
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|       several targets.  If an integrated assembler is not supported, then a
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|       system assembler is required.  For more details, see the <a
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|       href="CodeGenerator.html#targetfeatures">Target Features Matrix</a>.
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|   </li>
 | |
| 
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|   <li>The C backend has numerous problems and is not being actively maintained.
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|     Depending on it for anything serious is not advised.</li>
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| </ul>
 | |
| 
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| </div>
 | |
| 
 | |
| <!-- *********************************************************************** -->
 | |
| <h2>
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|   <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>
 | |
| 
 | |
| <!-- *********************************************************************** -->
 | |
| 
 | |
| <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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| 
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|   <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
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|   Last modified: $Date$
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| </address>
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| 
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| </body>
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| </html>
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