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<link rel="stylesheet" href="llvm.css" type="text/css">
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<title>LLVM 2.4 Release Notes</title>
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<body>
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2008-10-11 18:18:28 +00:00
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<div class="doc_title">LLVM 2.4 Release Notes</div>
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2003-10-02 04:57:28 +00:00
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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="#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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2003-10-02 04:57:28 +00:00
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<!-- *********************************************************************** -->
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2003-11-22 00:38:41 +00:00
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<div class="doc_text">
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2008-10-13 17:57:36 +00:00
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<p>This document contains the release notes for the LLVM Compiler
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Infrastructure, release 2.4. 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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2003-10-02 16:38:05 +00:00
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2004-12-07 08:04:13 +00:00
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<p>For more information about LLVM, including information about the latest
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2005-10-29 07:07:09 +00:00
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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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2003-10-02 04:57:28 +00:00
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2008-10-13 02:08:34 +00:00
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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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2008-10-11 18:18:28 +00:00
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<!-- Unfinished features in 2.4:
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Machine LICM
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Machine Sinking
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LegalizeDAGTypes
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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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-->
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2008-10-12 19:47:48 +00:00
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<!-- for announcement email:
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mention dev mtg
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Xcode 3.1 and 3.1.1.
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-->
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2008-02-10 07:46:44 +00:00
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2008-10-13 18:01:01 +00:00
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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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2006-04-18 06:18:36 +00:00
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</div>
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2008-10-13 18:01:01 +00:00
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<!-- *********************************************************************** -->
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2006-04-18 06:18:36 +00:00
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2007-05-14 06:56:09 +00:00
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<div class="doc_text">
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<p>
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The LLVM 2.4 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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2008-06-08 21:58:17 +00:00
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</p>
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2008-06-05 06:57:39 +00:00
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2008-06-08 21:58:17 +00:00
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</div>
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2008-06-05 06:57:39 +00:00
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2008-06-08 21:58:17 +00:00
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<!--=========================================================================-->
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2008-10-13 18:01:01 +00:00
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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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2008-06-08 21:58:17 +00:00
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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. Clang is continuing to make major strides forward in all
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areas. Its C and Objective-C parsing support is very solid, and the code
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generation support is far enough along to build many C applications. While not
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yet production quality, it is progressing very nicely. In addition, C++
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front-end work has started to make significant progress.</p>
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2008-10-27 09:27:33 +00:00
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<p>Clang, in conjunction with the <tt>ccc</tt> driver, is now usable as a
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replacement for gcc for building some small- to medium-sized C applications.
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Additionally, Clang now has code generation support for Objective-C on Mac OS X
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2008-10-27 09:27:33 +00:00
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platform. Major highlights include:</p>
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2008-10-14 23:25:09 +00:00
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<ul>
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<li> Clang/ccc pass almost all of the LLVM test suite on Mac OS X and Linux
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on the 32-bit x86 architecture. This includes significant C
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applications such as <a href="http://www.sqlite.org">sqlite3</a>,
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<a href="http://www.lua.org">lua</a>, and
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2008-10-27 09:27:33 +00:00
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<a href="http://www.clamav.net">Clam AntiVirus</a>. </li>
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<li> Clang can build the majority of Objective-C examples shipped with the
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2008-10-27 09:27:33 +00:00
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Mac OS X Developer Tools. </li>
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2008-10-14 23:25:09 +00:00
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</ul>
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2008-10-27 09:27:33 +00:00
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<p>Clang code generation still needs considerable testing and development,
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however. Some areas under active development include:</p>
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2008-10-14 23:25:09 +00:00
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<ul>
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<li> Improved support for C and Objective-C features, for example
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variable-length arrays, va_arg, exception handling (Obj-C), and garbage
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collection (Obj-C). </li>
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<li> ABI compatibility, especially for platforms other than 32-bit
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x86. </li>
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2008-10-14 23:25:09 +00:00
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</ul>
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2008-10-11 18:18:28 +00:00
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2008-10-13 18:11:54 +00:00
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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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2008-10-14 05:14:21 +00:00
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<p>The Clang project also includes an early stage static source code analysis
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tool for <a href="http://clang.llvm.org/StaticAnalysis.html">automatically
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finding bugs</a> in C and Objective-C programs. The tool performs a growing set
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2008-10-14 06:02:29 +00:00
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of checks to find bugs that occur on a specific path within a program. Examples
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2008-10-14 05:14:21 +00:00
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of bugs the tool finds include logic errors such as null dereferences,
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violations of various API rules, dead code, and potential memory leaks in
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2008-10-14 06:02:29 +00:00
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Objective-C programs. Since its inception, public feedback on the tool has been
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extremely positive, and conservative estimates put the number of real bugs it
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has found in industrial-quality software on the order of thousands.</p>
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2008-10-14 05:14:21 +00:00
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<p>The tool also provides a simple web GUI to inspect potential bugs found by
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2008-10-14 06:02:29 +00:00
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the tool. While still early in development, the GUI illustrates some of the key
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2008-10-14 05:14:21 +00:00
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features of Clang: accurate source location information, which is used by the
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GUI to highlight specific code expressions that relate to a bug (including those
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2008-10-27 09:27:33 +00:00
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that span multiple lines); and built-in knowledge of macros, which is used to
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2008-10-14 05:14:21 +00:00
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perform inline expansion of macros within the GUI itself.</p>
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2008-10-14 06:02:29 +00:00
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<p>The set of checks performed by the static analyzer is gradually expanding,
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2008-10-27 09:27:33 +00:00
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and future plans for the tool include full source-level inter-procedural
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analysis and deeper checks such as buffer overrun detection. There are many
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opportunities to extend and enhance the static analyzer, and anyone interested
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in working on this project is encouraged to get involved!</p>
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2008-06-08 21:58:17 +00:00
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</div>
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2008-10-13 18:01:01 +00:00
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<!--=========================================================================-->
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<div class="doc_subsection">
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2008-10-14 19:23:04 +00:00
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<a name="vmkit">VMKit: JVM/CLI Virtual Machine Implementation</a>
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2008-10-13 18:01:01 +00:00
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</div>
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<div class="doc_text">
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<p>
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2008-10-14 19:23:04 +00:00
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The <a href="http://vmkit.llvm.org/">VMKit project</a> is an implementation of
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2008-10-13 18:01:01 +00:00
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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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2008-10-15 20:25:04 +00:00
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<p>Following LLVM 2.4, VMKit has its first release 0.24 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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2008-10-13 18:01:01 +00:00
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2008-10-14 19:23:04 +00:00
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<ul>
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2008-10-27 09:27:33 +00:00
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<li> Support for generics in the .Net virtual machine.</li>
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<li> Initial support for the Mono class libraries. </li>
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<li> Support for MacOSX/x86, following LLVM's support for exceptions in
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2008-10-27 09:27:33 +00:00
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JIT on MacOSX/x86. </li>
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<li> A new vmkit driver: a program to run java or .net applications. The driver
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supports llvm command line arguments including the new "-fast" option. </li>
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2008-10-15 10:29:51 +00:00
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<li> A new memory allocation scheme in the JVM that makes unloading a
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class loader very fast. </li>
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<li> VMKit now follows the LLVM Makefile machinery. </li>
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2008-10-14 19:23:04 +00:00
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</ul>
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2008-10-13 18:01:01 +00:00
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</div>
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2008-06-08 21:58:17 +00:00
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<!-- *********************************************************************** -->
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<div class="doc_section">
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2008-10-13 18:01:01 +00:00
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<a name="whatsnew">What's New in LLVM?</a>
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2008-06-08 21:58:17 +00:00
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</div>
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<!-- *********************************************************************** -->
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2008-06-08 22:59:35 +00:00
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<div class="doc_text">
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2008-10-27 09:27:33 +00:00
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<p>This release includes a huge number of bug fixes, performance tweaks, and
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2008-10-13 17:57:36 +00:00
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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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2008-06-08 22:59:35 +00:00
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</p>
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</div>
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2008-06-08 21:34:41 +00:00
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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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2008-06-05 18:39:01 +00:00
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2008-06-08 21:34:41 +00:00
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<div class="doc_text">
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2008-06-05 06:57:39 +00:00
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2008-10-11 18:18:28 +00:00
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<p>LLVM 2.4 includes several major new capabilities:</p>
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2008-06-05 06:57:39 +00:00
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2008-06-08 21:34:41 +00:00
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<ul>
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2008-10-13 20:47:20 +00:00
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<li><p>The most visible end-user change in LLVM 2.4 is that it includes many
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2008-10-13 21:50:36 +00:00
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optimizations and changes to make -O0 compile times much faster. You should see
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2008-10-27 09:27:33 +00:00
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improvements in speed on the order of 30% (or more) than in LLVM 2.3. There are
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many pieces to this change described in more detail below. The speedups and new
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components can also be used for JIT compilers that want fast
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compilation.</p></li>
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2008-10-13 20:47:20 +00:00
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<li><p>The biggest change to the LLVM IR is that Multiple Return Values (which
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were introduced in LLVM 2.3) have been generalized to full support for "First
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Class Aggregate" values in LLVM 2.4. This means that LLVM IR supports using
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structs and arrays as values in a function. This capability is mostly useful
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for front-end authors, who prefer to treat things like complex numbers, simple
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2008-10-27 09:27:33 +00:00
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tuples, dope vectors, etc., as Value*'s instead of as a tuple of Value*'s or as
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2008-10-14 11:00:32 +00:00
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memory values. Bitcode files from LLVM 2.3 will automatically migrate to the
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general representation.</p></li>
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2008-10-13 20:47:20 +00:00
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<li><p>LLVM 2.4 also includes an initial port for the PIC16 microprocessor. This
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2008-10-27 09:27:33 +00:00
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target only has support for 8 bit registers, and a number of other crazy
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constraints. While the port is still in early development stages, it shows some
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interesting things you can do with LLVM.</p></li>
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2008-06-05 06:57:39 +00:00
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2008-06-05 06:25:56 +00:00
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</ul>
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2008-02-06 18:00:06 +00:00
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</div>
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2008-06-05 06:25:56 +00:00
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2008-02-06 18:00:06 +00:00
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<!--=========================================================================-->
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<div class="doc_subsection">
|
2008-06-08 21:34:41 +00:00
|
|
|
<a name="llvm-gcc">llvm-gcc 4.2 Improvements</a>
|
2008-02-06 18:00:06 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2008-10-13 20:47:20 +00:00
|
|
|
<p>LLVM fully supports the llvm-gcc 4.2 front-end, which marries the GCC
|
|
|
|
|
front-ends and driver with the LLVM optimizer and code generator. It currently
|
|
|
|
|
includes support for the C, C++, Objective-C, Ada, and Fortran front-ends.</p>
|
2008-02-06 18:00:06 +00:00
|
|
|
|
2008-06-08 22:59:35 +00:00
|
|
|
<ul>
|
2008-10-13 20:59:32 +00:00
|
|
|
<li>LLVM 2.4 supports the full set of atomic <tt>__sync_*</tt> builtins. LLVM
|
2008-10-27 09:27:33 +00:00
|
|
|
2.3 only supported those used by OpenMP, but 2.4 supports them all. Note that
|
|
|
|
|
while llvm-gcc supports all of these builtins, not all targets do. X86 support
|
|
|
|
|
them all in both 32-bit and 64-bit mode and PowerPC supports them all except for
|
|
|
|
|
the 64-bit operations when in 32-bit mode.</li>
|
2008-10-13 20:47:20 +00:00
|
|
|
|
2008-10-13 20:59:32 +00:00
|
|
|
<li>llvm-gcc now supports an <tt>-flimited-precision</tt> option, which tells
|
2008-10-27 09:27:33 +00:00
|
|
|
the compiler that it is okay to use low-precision approximations of certain libm
|
|
|
|
|
functions (like <tt>exp</tt>, <tt>log</tt>, etc). This allows you to get high
|
|
|
|
|
performance if you only need (say) 12-bits of precision.</li>
|
2008-10-13 20:47:20 +00:00
|
|
|
|
|
|
|
|
<li>llvm-gcc now supports a C language extension known as "<a
|
2008-10-17 14:43:58 +00:00
|
|
|
href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/002670.html">Blocks</a>".
|
|
|
|
|
This feature is similar to nested functions and closures, but does not
|
2008-10-27 09:27:33 +00:00
|
|
|
require stack trampolines (with most ABIs), and supports returning closures
|
2008-10-13 20:47:20 +00:00
|
|
|
from functions that define them. Note that actually <em>using</em> Blocks
|
|
|
|
|
requires a small runtime that is not included with llvm-gcc.</li>
|
|
|
|
|
|
|
|
|
|
<li>llvm-gcc now supports a new <tt>-flto</tt> option. On systems that support
|
|
|
|
|
transparent Link Time Optimization (currently Darwin systems with Xcode 3.1 and
|
|
|
|
|
later) this allows the use of LTO with other optimization levels like -Os.
|
|
|
|
|
Previously, LTO could only be used with -O4, which implied optimizations in
|
|
|
|
|
-O3 that can increase code size.</li>
|
2008-06-09 06:06:18 +00:00
|
|
|
</ul>
|
2008-06-05 06:25:56 +00:00
|
|
|
|
2007-05-14 06:56:09 +00:00
|
|
|
</div>
|
|
|
|
|
|
2008-06-05 06:25:56 +00:00
|
|
|
|
2008-02-10 08:17:19 +00:00
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="coreimprovements">LLVM Core Improvements</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
2008-10-27 09:27:33 +00:00
|
|
|
<p>New features include:</p>
|
2008-02-10 08:17:19 +00:00
|
|
|
|
2008-06-08 22:59:35 +00:00
|
|
|
<ul>
|
2008-10-14 11:00:32 +00:00
|
|
|
<li>A major change to the <tt>Use</tt> class landed, which shrank it by 25%. Since
|
2008-10-13 20:59:32 +00:00
|
|
|
this is a pervasive part of the LLVM, it ended up reducing the memory use of
|
|
|
|
|
LLVM IR in general by 15% for most programs.</li>
|
|
|
|
|
|
|
|
|
|
<li>Values with no names are now pretty printed by <tt>llvm-dis</tt> more
|
|
|
|
|
nicely. They now print as "<tt>%3 = add i32 %A, 4</tt>" instead of
|
|
|
|
|
"<tt>add i32 %A, 4 ; <i32>:3</tt>", which makes it much easier to read.
|
|
|
|
|
</li>
|
|
|
|
|
|
|
|
|
|
<li>LLVM 2.4 includes some changes for better vector support. First, the shift
|
2008-10-27 09:27:33 +00:00
|
|
|
operations (<tt>shl</tt>, <tt>ashr</tt>, and <tt>lshr</tt>) now all support
|
|
|
|
|
vectors and do an element-by-element shift (shifts of the whole vector can be
|
2008-11-10 05:40:34 +00:00
|
|
|
accomplished by bitcasting the vector to <tt><1 x i128></tt>, for example). Second,
|
2008-10-27 09:27:33 +00:00
|
|
|
there is initial support in development for vector comparisons with the
|
|
|
|
|
<tt><a href="LangRef.html#i_fcmp">fcmp</a>/<a href="LangRef.html#i_icmp">icmp</a></tt>
|
2008-10-14 00:52:49 +00:00
|
|
|
instructions. These instructions compare two vectors and return a vector of
|
2008-10-27 09:27:33 +00:00
|
|
|
<tt>i1</tt>'s for each result. Note that there is very little codegen support
|
|
|
|
|
available for any of these IR features though.</li>
|
2008-10-13 20:59:32 +00:00
|
|
|
|
|
|
|
|
<li>A new <tt>DebugInfoBuilder</tt> class is available, which makes it much
|
|
|
|
|
easier for front-ends to create debug info descriptors, similar to the way that
|
2008-10-14 11:31:14 +00:00
|
|
|
<tt>IRBuilder</tt> makes it easier to create LLVM IR.</li>
|
2008-10-13 20:59:32 +00:00
|
|
|
|
2008-10-14 16:13:59 +00:00
|
|
|
<li>The <tt>IRBuilder</tt> class is now parameterized by a class responsible
|
2008-10-14 11:00:32 +00:00
|
|
|
for constant folding. The default <tt>ConstantFolder</tt> class does target independent
|
|
|
|
|
constant folding. The <tt>NoFolder</tt> class does no constant folding at all, which is
|
|
|
|
|
useful when learning how LLVM works. The <tt>TargetFolder</tt> class folds the most,
|
2008-10-14 07:06:37 +00:00
|
|
|
doing target dependent constant folding.</li>
|
|
|
|
|
|
2008-10-27 09:27:33 +00:00
|
|
|
<li>LLVM now supports "function attributes", which allow us to separate return
|
2008-10-13 20:59:32 +00:00
|
|
|
value attributes from function attributes. LLVM now supports attributes on a
|
|
|
|
|
function itself, a return value, and its parameters. New supported function
|
2008-10-27 09:27:33 +00:00
|
|
|
attributes include <tt>noinline/alwaysinline</tt> and the <tt>opt-size</tt> flag,
|
|
|
|
|
which says the function should be optimized for code size.</li>
|
2008-10-13 20:59:32 +00:00
|
|
|
|
2008-10-12 18:30:33 +00:00
|
|
|
<li>LLVM IR now directly represents "common" linkage, instead of
|
|
|
|
|
representing it as a form of weak linkage.</li>
|
2008-10-13 20:59:32 +00:00
|
|
|
|
2008-02-10 08:17:19 +00:00
|
|
|
</ul>
|
2008-10-13 02:08:34 +00:00
|
|
|
|
2008-02-10 08:17:19 +00:00
|
|
|
</div>
|
|
|
|
|
|
2007-09-21 03:54:09 +00:00
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
2008-02-10 07:46:44 +00:00
|
|
|
<a name="optimizer">Optimizer Improvements</a>
|
2007-09-21 03:54:09 +00:00
|
|
|
</div>
|
2007-05-18 06:33:02 +00:00
|
|
|
|
2006-04-18 06:18:36 +00:00
|
|
|
<div class="doc_text">
|
2007-09-21 03:54:09 +00:00
|
|
|
|
2008-10-13 21:50:36 +00:00
|
|
|
<p>In addition to a huge array of bug fixes and minor performance tweaks, this
|
|
|
|
|
release includes a few major enhancements and additions to the optimizers:</p>
|
2007-09-26 05:44:21 +00:00
|
|
|
|
2006-11-18 07:51:14 +00:00
|
|
|
<ul>
|
2007-05-16 23:25:46 +00:00
|
|
|
|
2008-10-13 21:50:36 +00:00
|
|
|
<li>The Global Value Numbering (GVN) pass now does local Partial Redundancy
|
|
|
|
|
Elimination (PRE) to eliminate some partially redundant expressions in cases
|
|
|
|
|
where doing so won't grow code size.</li>
|
2008-10-12 19:47:48 +00:00
|
|
|
|
2008-10-13 21:50:36 +00:00
|
|
|
<li>LLVM 2.4 includes a new loop deletion pass (which removes output-free
|
|
|
|
|
provably-finite loops) and a rewritten Aggressive Dead Code Elimination (ADCE)
|
|
|
|
|
pass that no longer uses control dependence information. These changes speed up
|
2008-10-14 11:31:14 +00:00
|
|
|
the optimizer and also prevent it from deleting output-free infinite
|
2008-10-13 21:50:36 +00:00
|
|
|
loops.</li>
|
2008-10-12 19:47:48 +00:00
|
|
|
|
2008-10-13 21:50:36 +00:00
|
|
|
<li>The new AddReadAttrs pass works out which functions are read-only or
|
2008-10-14 11:31:14 +00:00
|
|
|
read-none (these correspond to 'pure' and 'const' in GCC) and marks them
|
2008-10-13 21:50:36 +00:00
|
|
|
with the appropriate attribute.</li>
|
2008-10-12 18:30:33 +00:00
|
|
|
|
2008-10-13 21:50:36 +00:00
|
|
|
<li>LLVM 2.4 now includes a new SparsePropagation framework, which makes it
|
|
|
|
|
trivial to build lattice-based dataflow solvers that operate over LLVM IR. Using
|
|
|
|
|
this interface means that you just define objects to represent your lattice
|
|
|
|
|
values and the transfer functions that operate on them. It handles the
|
|
|
|
|
mechanics of worklist processing, liveness tracking, handling PHI nodes,
|
|
|
|
|
etc.</li>
|
2008-10-12 18:30:33 +00:00
|
|
|
|
2008-10-14 06:02:29 +00:00
|
|
|
<li>The Loop Strength Reduction and induction variable optimization passes have
|
|
|
|
|
several improvements to avoid inserting MAX expressions, to optimize simple
|
|
|
|
|
floating point induction variables and to analyze trip counts of more
|
|
|
|
|
loops.</li>
|
|
|
|
|
|
2008-10-12 19:47:48 +00:00
|
|
|
<li>Various helper functions (ComputeMaskedBits, ComputeNumSignBits, etc) were
|
2008-10-13 21:50:36 +00:00
|
|
|
pulled out of the Instruction Combining pass and put into a new
|
|
|
|
|
<tt>ValueTracking.h</tt> header, where they can be reused by other passes.</li>
|
|
|
|
|
|
|
|
|
|
<li>The tail duplication pass has been removed from the standard optimizer
|
|
|
|
|
sequence used by llvm-gcc. This pass still exists, but the benefits it once
|
|
|
|
|
provided are now achieved by other passes.</li>
|
2008-10-12 19:47:48 +00:00
|
|
|
|
2008-06-08 02:45:07 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="codegen">Code Generator Improvements</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2008-10-14 11:31:14 +00:00
|
|
|
<p>We have put a significant amount of work into the code generator infrastructure,
|
2008-06-08 02:45:07 +00:00
|
|
|
which allows us to implement more aggressive algorithms and make it run
|
|
|
|
|
faster:</p>
|
|
|
|
|
|
|
|
|
|
<ul>
|
2008-10-13 21:50:36 +00:00
|
|
|
<li>The target-independent code generator supports (and the X86 backend
|
|
|
|
|
currently implements) a new interface for "fast" instruction selection. This
|
|
|
|
|
interface is optimized to produce code as quickly as possible, sacrificing
|
|
|
|
|
code quality to do it. This is used by default at -O0 or when using
|
|
|
|
|
"llc -fast" on X86. It is straight-forward to add support for
|
|
|
|
|
other targets if faster -O0 compilation is desired.</li>
|
|
|
|
|
|
|
|
|
|
<li>In addition to the new 'fast' instruction selection path, many existing
|
|
|
|
|
pieces of the code generator have been optimized in significant ways.
|
|
|
|
|
SelectionDAG's are now pool allocated and use better algorithms in many
|
2008-10-14 11:31:14 +00:00
|
|
|
places, the ".s" file printers now use <tt>raw_ostream</tt> to emit text much faster,
|
2008-10-13 21:50:36 +00:00
|
|
|
etc. The end result of these improvements is that the compiler also takes
|
|
|
|
|
substantially less time to generate code that is just as good (and often
|
|
|
|
|
better) than before.</li>
|
|
|
|
|
|
2008-10-14 11:31:14 +00:00
|
|
|
<li>Each target has been split to separate the ".s" file printing logic from the
|
2008-10-13 21:50:36 +00:00
|
|
|
rest of the target. This enables JIT compilers that don't link in the
|
2008-10-14 11:31:14 +00:00
|
|
|
(somewhat large) code and data tables used for printing a ".s" file.</li>
|
2008-10-13 21:50:36 +00:00
|
|
|
|
|
|
|
|
<li>The code generator now includes a "stack slot coloring" pass, which packs
|
|
|
|
|
together individual spilled values into common stack slots. This reduces
|
|
|
|
|
the size of stack frames with many spills, which tends to increase L1 cache
|
|
|
|
|
effectiveness.</li>
|
|
|
|
|
|
|
|
|
|
<li>Various pieces of the register allocator (e.g. the coalescer and two-address
|
|
|
|
|
operation elimination pass) now know how to rematerialize trivial operations
|
|
|
|
|
to avoid copies and include several other optimizations.</li>
|
|
|
|
|
|
|
|
|
|
<li>The <a href="CodeGenerator.html#selectiondag_process">graphs</a> produced by
|
|
|
|
|
the <tt>llc -view-*-dags</tt> options are now significantly prettier and
|
|
|
|
|
easier to read.</li>
|
|
|
|
|
|
|
|
|
|
<li>LLVM 2.4 includes a new register allocator based on Partitioned Boolean
|
|
|
|
|
Quadratic Programming (PBQP). This register allocator is still in
|
|
|
|
|
development, but is very simple and clean.</li>
|
2008-06-08 02:45:07 +00:00
|
|
|
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
2007-09-21 03:54:09 +00:00
|
|
|
|
2006-04-18 06:18:36 +00:00
|
|
|
</div>
|
|
|
|
|
|
2007-09-21 03:54:09 +00:00
|
|
|
|
|
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
2008-10-13 22:06:31 +00:00
|
|
|
<a name="targetspecific">Target Specific Improvements</a>
|
2007-09-21 03:54:09 +00:00
|
|
|
</div>
|
2006-11-18 07:51:14 +00:00
|
|
|
|
2006-04-18 06:18:36 +00:00
|
|
|
<div class="doc_text">
|
2008-02-10 08:17:19 +00:00
|
|
|
<p>New target-specific features include:
|
2007-05-14 06:56:09 +00:00
|
|
|
</p>
|
|
|
|
|
|
|
|
|
|
<ul>
|
2008-10-12 19:47:48 +00:00
|
|
|
<li>Exception handling is supported by default on Linux/x86-64.</li>
|
2008-10-13 17:32:15 +00:00
|
|
|
<li>Position Independent Code (PIC) is now supported on Linux/x86-64.</li>
|
2008-10-27 10:17:24 +00:00
|
|
|
<li><tt>@llvm.frameaddress</tt> now supports getting the frame address of stack frames
|
2008-10-14 06:02:29 +00:00
|
|
|
> 0 on x86/x86-64.</li>
|
2008-10-25 14:56:26 +00:00
|
|
|
<li>MIPS has improved a lot since last release, the most important changes
|
|
|
|
|
are: Little endian support, floating point support, allegrex core and
|
|
|
|
|
intrinsics support. O32 ABI is improved but isn't complete. The EABI
|
|
|
|
|
was implemented and is fully supported. We also have support for small
|
|
|
|
|
sections and gp_rel relocation for its access, a threshold in bytes can be
|
|
|
|
|
specified through command line.</li>
|
2008-10-13 22:06:31 +00:00
|
|
|
<li>The PowerPC backend now supports trampolines.</li>
|
2008-06-05 08:02:49 +00:00
|
|
|
</ul>
|
|
|
|
|
|
2008-10-13 02:08:34 +00:00
|
|
|
</div>
|
2008-06-05 08:02:49 +00:00
|
|
|
|
|
|
|
|
|
2007-09-21 03:54:09 +00:00
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="otherimprovements">Other Improvements</a>
|
|
|
|
|
</div>
|
2007-05-14 06:56:09 +00:00
|
|
|
|
2006-04-18 06:32:08 +00:00
|
|
|
<div class="doc_text">
|
2007-09-21 03:54:09 +00:00
|
|
|
<p>New features include:
|
|
|
|
|
</p>
|
2006-04-18 06:18:36 +00:00
|
|
|
|
2006-02-05 06:39:36 +00:00
|
|
|
<ul>
|
2008-10-13 02:46:01 +00:00
|
|
|
<li><tt>llvmc2</tt> (the generic compiler driver) gained plugin
|
2008-10-13 22:06:31 +00:00
|
|
|
support. It is now easier to experiment with <tt>llvmc2</tt> and
|
|
|
|
|
build your own tools based on it.</li>
|
|
|
|
|
|
|
|
|
|
<li>LLVM 2.4 includes a number of new generic algorithms and data structures,
|
2008-11-10 05:40:34 +00:00
|
|
|
including a scoped hash table, 'immutable' data structures, a simple
|
2008-10-14 15:14:55 +00:00
|
|
|
free-list manager, and a <tt>raw_ostream</tt> class.
|
|
|
|
|
The <tt>raw_ostream</tt> class and
|
2008-10-13 22:06:31 +00:00
|
|
|
<tt>format</tt> allow for efficient file output, and various pieces of LLVM
|
|
|
|
|
have switched over to use it. The eventual goal is to eliminate
|
2008-11-10 05:40:34 +00:00
|
|
|
use of <tt>std::ostream</tt> in favor of it.</li>
|
2008-10-13 22:06:31 +00:00
|
|
|
|
2008-11-04 21:48:10 +00:00
|
|
|
<li>LLVM 2.4 includes an optional build system based on CMake. It
|
|
|
|
|
still is in its early stages but can be useful for Visual C++
|
|
|
|
|
users who can not use the Visual Studio IDE.</li>
|
2008-11-04 18:40:27 +00:00
|
|
|
|
2007-05-17 21:41:31 +00:00
|
|
|
</ul>
|
2008-10-13 02:08:34 +00:00
|
|
|
|
2007-05-17 21:41:31 +00:00
|
|
|
</div>
|
2006-03-03 00:34:26 +00:00
|
|
|
|
2008-10-13 17:57:36 +00:00
|
|
|
<!--=========================================================================-->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="changes">Major Changes and Removed Features</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
<p>If you're already an LLVM user or developer with out-of-tree changes based
|
|
|
|
|
on LLVM 2.3, this section lists some "gotchas" that you may run into upgrading
|
|
|
|
|
from the previous release.</p>
|
2008-10-13 18:01:01 +00:00
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
<ul>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
<li>The LLVM IR generated by llvm-gcc no longer names all instructions. This
|
|
|
|
|
makes it run faster, but may be more confusing to some people. If you
|
|
|
|
|
prefer to have names, the '<tt>opt -instnamer</tt>' pass will add names to
|
|
|
|
|
all instructions.</li>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
<li>The LoadVN and GCSE passes have been removed from the tree. They are
|
|
|
|
|
obsolete and have been replaced with the GVN and MemoryDependence passes.
|
|
|
|
|
</li>
|
|
|
|
|
</ul>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
|
|
|
|
|
<p>In addition, many APIs have changed in this release. Some of the major LLVM
|
|
|
|
|
API changes are:</p>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
|
|
|
|
<ul>
|
|
|
|
|
|
2008-10-14 20:03:43 +00:00
|
|
|
<li>Now, function attributes and return value attributes are managed
|
2008-10-15 10:47:24 +00:00
|
|
|
separately. Interface exported by <tt>ParameterAttributes.h</tt> header is now
|
2008-11-10 05:40:34 +00:00
|
|
|
exported by <tt>Attributes.h</tt> header. The new attributes interface changes are:
|
2008-10-14 20:03:43 +00:00
|
|
|
<ul>
|
|
|
|
|
<li><tt>getParamAttrs</tt> method is now replaced by
|
|
|
|
|
<tt>getParamAttributes</tt>, <tt>getRetAttributes</tt> and
|
|
|
|
|
<tt>getFnAttributes</tt> methods.</li>
|
|
|
|
|
<li> Return value attributes are stored at index 0. Function attributes are
|
|
|
|
|
stored at index ~0U. Parameter attributes are stored at index that matches
|
|
|
|
|
parameter number.</li>
|
|
|
|
|
<li> <tt>ParamAttr</tt> namespace is now renamed as <tt>Attribute</tt>.</li>
|
2008-10-15 10:29:51 +00:00
|
|
|
<li> The name of the class that manages reference count of opaque
|
2008-10-14 20:03:43 +00:00
|
|
|
attributes is changed from <tt>PAListPtr</tt> to <tt>AttrListPtr</tt>.</li>
|
|
|
|
|
<li> <tt>ParamAttrsWithIndex</tt> is now renamed as <tt>AttributeWithIndex</tt>.
|
|
|
|
|
</li>
|
|
|
|
|
</ul>
|
|
|
|
|
</li>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
|
|
|
|
<li>The <tt>DbgStopPointInst</tt> methods <tt>getDirectory</tt> and
|
|
|
|
|
<tt>getFileName</tt> now return <tt>Value*</tt> instead of strings. These can be
|
|
|
|
|
converted to strings using <tt>llvm::GetConstantStringInfo</tt> defined via
|
2008-10-14 11:31:14 +00:00
|
|
|
"<tt>llvm/Analysis/ValueTracking.h</tt>".</li>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
2008-10-13 22:06:31 +00:00
|
|
|
<li>The APIs to create various instructions have changed from lower case
|
|
|
|
|
"create" methods to upper case "Create" methods (e.g.
|
|
|
|
|
<tt>BinaryOperator::create</tt>). LLVM 2.4 includes both cases, but the
|
2008-11-10 05:40:34 +00:00
|
|
|
lower case ones are removed in mainline (2.5 and later), please migrate.</li>
|
2008-10-13 22:06:31 +00:00
|
|
|
|
2008-10-14 11:31:14 +00:00
|
|
|
<li>Various header files like "<tt>llvm/ADT/iterator</tt>" were given a ".h" suffix.
|
|
|
|
|
Change your code to #include "<tt>llvm/ADT/iterator.h</tt>" instead.</li>
|
2008-10-13 17:57:36 +00:00
|
|
|
|
2008-10-27 04:39:23 +00:00
|
|
|
<li>The <tt>getresult</tt> instruction has been removed and replaced with the
|
|
|
|
|
<tt>extractvalue</tt> instruction. This is part of support for first class
|
|
|
|
|
aggregates.</li>
|
|
|
|
|
|
2008-10-14 11:31:14 +00:00
|
|
|
<li>In the code generator, many <tt>MachineOperand</tt> predicates were renamed to be
|
2008-10-14 06:37:11 +00:00
|
|
|
shorter (e.g. <tt>isFrameIndex()</tt> -> <tt>isFI()</tt>),
|
|
|
|
|
<tt>SDOperand</tt> was renamed to <tt>SDValue</tt> (and the "<tt>Val</tt>"
|
|
|
|
|
member was changed to be the <tt>getNode()</tt> accessor), and the
|
|
|
|
|
<tt>MVT::ValueType</tt> enum has been replaced with an "<tt>MVT</tt>"
|
2008-10-14 17:06:44 +00:00
|
|
|
struct. The <tt>getSignExtended</tt> and <tt>getValue</tt> methods in the
|
|
|
|
|
ConstantSDNode class were renamed to <tt>getSExtValue</tt> and
|
|
|
|
|
<tt>getZExtValue</tt> respectively, to be more consistent with
|
|
|
|
|
the <tt>ConstantInt</tt> class.</li>
|
2008-10-13 17:57:36 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2003-10-02 16:38:05 +00:00
|
|
|
<!-- *********************************************************************** -->
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_section">
|
|
|
|
|
<a name="portability">Portability and Supported Platforms</a>
|
|
|
|
|
</div>
|
2003-10-02 16:38:05 +00:00
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2004-12-08 20:35:47 +00:00
|
|
|
<p>LLVM is known to work on the following platforms:</p>
|
2004-06-01 18:22:41 +00:00
|
|
|
|
|
|
|
|
<ul>
|
2008-11-10 05:40:34 +00:00
|
|
|
<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>
|
2008-02-06 18:00:06 +00:00
|
|
|
<li>Intel and AMD machines running on Win32 using MinGW libraries (native).</li>
|
2004-12-07 08:04:13 +00:00
|
|
|
<li>Intel and AMD machines running on Win32 with the Cygwin libraries (limited
|
|
|
|
|
support is available for native builds with Visual C++).</li>
|
2008-06-05 18:39:01 +00:00
|
|
|
<li>Sun UltraSPARC workstations running Solaris 10.</li>
|
2005-05-13 20:28:15 +00:00
|
|
|
<li>Alpha-based machines running Debian GNU/Linux.</li>
|
2008-06-05 18:39:01 +00:00
|
|
|
<li>Itanium-based (IA64) machines running Linux and HP-UX.</li>
|
2004-06-01 18:22:41 +00:00
|
|
|
</ul>
|
|
|
|
|
|
2008-06-05 06:57:39 +00:00
|
|
|
<p>The core LLVM infrastructure uses GNU autoconf to adapt itself
|
2004-05-09 05:28:35 +00:00
|
|
|
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>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_section">
|
|
|
|
|
<a name="knownproblems">Known Problems</a>
|
|
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2008-11-10 05:40:34 +00:00
|
|
|
<p>This section contains significant known problems with the LLVM system,
|
|
|
|
|
listed by component. If you run into a problem, please check the <a
|
2005-10-29 07:07:09 +00:00
|
|
|
href="http://llvm.org/bugs/">LLVM bug database</a> and submit a bug if
|
2003-12-12 21:22:16 +00:00
|
|
|
there isn't already one.</p>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2004-03-14 02:03:02 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="experimental">Experimental features included with this release</a>
|
|
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2004-03-14 02:03:02 +00:00
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2004-05-12 21:46:05 +00:00
|
|
|
<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
|
2008-02-12 06:29:45 +00:00
|
|
|
components, please contact us on the <a
|
|
|
|
|
href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVMdev list</a>.</p>
|
2004-03-14 02:03:02 +00:00
|
|
|
|
|
|
|
|
<ul>
|
2008-10-14 11:31:14 +00:00
|
|
|
<li>The MSIL, IA64, Alpha, SPU, MIPS, and PIC16 backends are experimental.</li>
|
2008-06-08 20:18:35 +00:00
|
|
|
<li>The llc "<tt>-filetype=asm</tt>" (the default) is the only supported
|
2008-02-06 06:30:34 +00:00
|
|
|
value for this option.</li>
|
2004-03-14 02:03:02 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2005-11-08 21:11:33 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2006-11-18 07:51:14 +00:00
|
|
|
<a name="x86-be">Known problems with the X86 back-end</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2008-06-08 10:24:13 +00:00
|
|
|
<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>
|
2008-06-08 21:19:07 +00:00
|
|
|
<li>The X86 backend generates inefficient floating point code when configured
|
|
|
|
|
to generate code for systems that don't have SSE2.</li>
|
2008-06-08 19:38:43 +00:00
|
|
|
<li>Win64 code generation wasn't widely tested. Everything should work, but we
|
2008-06-08 10:24:13 +00:00
|
|
|
expect small issues to happen. Also, llvm-gcc cannot build mingw64 runtime
|
|
|
|
|
currently due
|
|
|
|
|
to <a href="http://llvm.org/PR2255">several</a>
|
2008-06-08 23:12:47 +00:00
|
|
|
<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>
|
2008-06-08 23:05:11 +00:00
|
|
|
<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>
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="ppc-be">Known problems with the PowerPC back-end</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2007-05-15 09:21:28 +00:00
|
|
|
<li>The Linux PPC32/ABI support needs testing for the interpreter and static
|
2007-05-23 04:39:32 +00:00
|
|
|
compilation, and lacks support for debug information.</li>
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2007-05-14 06:56:09 +00:00
|
|
|
<a name="arm-be">Known problems with the ARM back-end</a>
|
2006-11-18 07:51:14 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2007-05-23 04:39:32 +00:00
|
|
|
<li>Thumb mode works only on ARMv6 or higher processors. On sub-ARMv6
|
2007-09-26 15:59:54 +00:00
|
|
|
processors, thumb programs can crash or produce wrong
|
2007-05-23 04:39:32 +00:00
|
|
|
results (<a href="http://llvm.org/PR1388">PR1388</a>).</li>
|
2007-05-14 06:56:09 +00:00
|
|
|
<li>Compilation for ARM Linux OABI (old ABI) is supported, but not fully tested.
|
|
|
|
|
</li>
|
2008-06-08 21:19:07 +00:00
|
|
|
<li>There is a bug in QEMU-ARM (<= 0.9.0) which causes it to incorrectly
|
|
|
|
|
execute
|
2007-05-23 04:39:32 +00:00
|
|
|
programs compiled with LLVM. Please use more recent versions of QEMU.</li>
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2007-05-14 06:56:09 +00:00
|
|
|
<a name="sparc-be">Known problems with the SPARC back-end</a>
|
2006-11-18 07:51:14 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2007-05-14 06:56:09 +00:00
|
|
|
<li>The SPARC backend only supports the 32-bit SPARC ABI (-m32), it does not
|
|
|
|
|
support the 64-bit SPARC ABI (-m64).</li>
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
2008-10-25 14:56:26 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<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>
|
|
|
|
|
|
2006-11-18 07:51:14 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="alpha-be">Known problems with the Alpha back-end</a>
|
2005-11-08 21:11:33 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2006-11-18 07:51:14 +00:00
|
|
|
|
|
|
|
|
<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>
|
2008-06-08 23:12:47 +00:00
|
|
|
<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
|
2008-10-15 10:47:24 +00:00
|
|
|
are interested, please contact the LLVMdev mailing list.</li>
|
2005-11-08 21:11:33 +00:00
|
|
|
</ul>
|
2006-11-18 07:51:14 +00:00
|
|
|
|
2005-11-08 21:11:33 +00:00
|
|
|
</div>
|
|
|
|
|
|
2006-11-18 07:51:14 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2007-05-14 06:56:09 +00:00
|
|
|
<a name="c-be">Known problems with the C back-end</a>
|
2006-11-18 07:51:14 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
|
|
|
|
<ul>
|
2008-06-05 06:35:40 +00:00
|
|
|
<li><a href="http://llvm.org/PR802">The C backend has only basic support for
|
|
|
|
|
inline assembly code</a>.</li>
|
2007-09-26 06:01:35 +00:00
|
|
|
<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
|
2008-06-08 20:18:35 +00:00
|
|
|
C++ code compiled with llc or native compilers.</li>
|
2008-02-10 13:40:55 +00:00
|
|
|
<li>The C backend does not support all exception handling constructs.</li>
|
2006-11-18 07:51:14 +00:00
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
</div>
|
2005-11-08 21:11:33 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2008-06-05 06:35:40 +00:00
|
|
|
<a name="c-fe">Known problems with the llvm-gcc C front-end</a>
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
2003-10-02 05:07:23 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_text">
|
2006-03-03 00:34:26 +00:00
|
|
|
|
2008-02-06 18:00:06 +00:00
|
|
|
<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
|
2008-10-15 10:47:24 +00:00
|
|
|
LLVMdev mailing list if you are interested.</p>
|
2006-11-18 07:51:14 +00:00
|
|
|
|
2008-06-05 06:35:40 +00:00
|
|
|
<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
|
2008-06-08 20:18:35 +00:00
|
|
|
supported on some targets (these are used when you take the address of a
|
|
|
|
|
nested function).</p>
|
2007-09-26 15:59:54 +00:00
|
|
|
|
2008-06-05 06:35:40 +00:00
|
|
|
<p>If you run into GCC extensions which are not supported, please let us know.
|
|
|
|
|
</p>
|
2003-11-22 00:38:41 +00:00
|
|
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2008-06-05 06:35:40 +00:00
|
|
|
<a name="c++-fe">Known problems with the llvm-gcc C++ front-end</a>
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2007-05-14 06:56:09 +00:00
|
|
|
<p>The C++ front-end is considered to be fully
|
2004-12-07 08:04:13 +00:00
|
|
|
tested and works for a number of non-trivial programs, including LLVM
|
2007-05-14 06:56:09 +00:00
|
|
|
itself, Qt, Mozilla, etc.</p>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<ul>
|
2008-10-11 18:27:16 +00:00
|
|
|
<li>Exception handling works well on the X86 and PowerPC targets. Currently
|
2008-11-10 05:40:34 +00:00
|
|
|
only Linux and Darwin targets are supported (both 32 and 64 bit).</li>
|
2003-11-22 00:38:41 +00:00
|
|
|
</ul>
|
2003-10-07 22:14:37 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
2003-10-07 22:14:37 +00:00
|
|
|
|
2008-10-30 03:58:13 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
|
|
|
|
<a name="fortran-fe">Known problems with the llvm-gcc Fortran front-end</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc_text">
|
2008-11-04 21:50:59 +00:00
|
|
|
<ul>
|
2008-10-30 03:58:13 +00:00
|
|
|
<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>
|
2008-11-04 21:50:59 +00:00
|
|
|
</ul>
|
2008-10-30 03:58:13 +00:00
|
|
|
</div>
|
2006-04-18 06:18:36 +00:00
|
|
|
|
2008-02-12 06:29:45 +00:00
|
|
|
<!-- ======================================================================= -->
|
|
|
|
|
<div class="doc_subsection">
|
2008-06-05 06:35:40 +00:00
|
|
|
<a name="ada-fe">Known problems with the llvm-gcc Ada front-end</a>
|
2008-02-12 06:29:45 +00:00
|
|
|
</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>
|
2008-06-08 20:18:35 +00:00
|
|
|
<li>The Ada front-end currently only builds on X86-32. This is mainly due
|
2008-02-12 06:29:45 +00:00
|
|
|
to lack of trampoline support (pointers to nested functions) on other platforms,
|
2008-06-08 20:18:35 +00:00
|
|
|
however it <a href="http://llvm.org/PR2006">also fails to build on X86-64</a>
|
2008-02-12 06:29:45 +00:00
|
|
|
which does support trampolines.</li>
|
|
|
|
|
<li>The Ada front-end <a href="http://llvm.org/PR2007">fails to bootstrap</a>.
|
|
|
|
|
Workaround: configure with --disable-bootstrap.</li>
|
2008-10-13 17:27:23 +00:00
|
|
|
<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).</li>
|
|
|
|
|
<li>Some gcc specific Ada tests continue to crash the compiler.</li>
|
2008-02-12 06:29:45 +00:00
|
|
|
<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>
|
2008-06-08 21:19:07 +00:00
|
|
|
<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>
|
2008-02-12 06:29:45 +00:00
|
|
|
</ul>
|
|
|
|
|
</div>
|
|
|
|
|
|
2003-10-02 04:57:28 +00:00
|
|
|
<!-- *********************************************************************** -->
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_section">
|
|
|
|
|
<a name="additionalinfo">Additional Information</a>
|
|
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<div class="doc_text">
|
|
|
|
|
|
2005-05-16 17:13:10 +00:00
|
|
|
<p>A wide variety of additional information is available on the <a
|
2007-05-18 00:44:29 +00:00
|
|
|
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
|
2007-07-09 08:04:31 +00:00
|
|
|
contains versions of the API documentation which is up-to-date with the
|
|
|
|
|
Subversion version of the source code.
|
2005-03-30 19:14:24 +00:00
|
|
|
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>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<p>If you have any questions or comments about LLVM, please feel free to contact
|
2005-10-29 07:07:09 +00:00
|
|
|
us via the <a href="http://llvm.org/docs/#maillist"> mailing
|
2003-12-12 21:22:16 +00:00
|
|
|
lists</a>.</p>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
</div>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
|
|
|
|
<!-- *********************************************************************** -->
|
|
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
<hr>
|
2003-11-22 01:23:39 +00:00
|
|
|
<address>
|
2003-12-21 22:53:21 +00:00
|
|
|
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
|
2003-11-22 01:23:39 +00:00
|
|
|
src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
|
|
|
|
|
<a href="http://validator.w3.org/check/referer"><img
|
2008-02-10 08:18:42 +00:00
|
|
|
src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
|
2003-11-22 01:23:39 +00:00
|
|
|
|
2007-05-18 00:44:29 +00:00
|
|
|
<a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
|
2003-11-22 00:38:41 +00:00
|
|
|
Last modified: $Date$
|
2003-11-22 01:23:39 +00:00
|
|
|
</address>
|
2003-10-02 04:57:28 +00:00
|
|
|
|
2003-11-22 00:38:41 +00:00
|
|
|
</body>
|
|
|
|
|
</html>
|
