107 lines
4.3 KiB
HTML
107 lines
4.3 KiB
HTML
<!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=ISO-8859-1" />
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<title>Clang - Performance</title>
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<link type="text/css" rel="stylesheet" href="menu.css" />
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<link type="text/css" rel="stylesheet" href="content.css" />
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<style type="text/css">
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</style>
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</head>
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<body>
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<!--#include virtual="menu.html.incl"-->
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<div id="content">
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<!--*************************************************************************-->
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<h1>Clang - Performance</h1>
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<!--*************************************************************************-->
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<p>This page shows the compile time performance of Clang on two
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interesting benchmarks:
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<ul>
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<li><i>Sketch</i>: The Objective-C example application shipped on
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Mac OS X as part of Xcode. <i>Sketch</i> is indicative of a
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"typical" Objective-C app. The source itself has a relatively
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small amount of code (~7,500 lines of source code), but it relies
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on the extensive Cocoa APIs to build its functionality. Like many
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Objective-C applications, it includes <tt>Cocoa/Cocoa.h</tt> in
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all of its source files, which represents a significant stress
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test of the front-end's performance on lexing, preprocessing,
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parsing, and syntax analysis.</li>
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<li><i>176.gcc</i>: This is the gcc-2.7.2.2 code base as present in
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SPECINT 2000. In contrast to Sketch, <i>176.gcc</i> consists of a
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large amount of C source code (~200,000 lines) with few system
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dependencies. This stresses the back-end's performance on generating
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assembly code and debug information.</li>
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</ul>
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</p>
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<p>
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For previous performance numbers, please
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go <a href="performance-2009-03-02.html">here</a>.
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</p>
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<h2><a name="experiments">Experiments</a></h2>
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<p>Measurements are done by running a full build (using xcodebuild or
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make for Sketch and 176.gcc respectively) using Clang and gcc 4.2 as
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compilers.</p>
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<p>In order to track the performance of various subsystems the timings
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have been broken down into separate stages where possible. This is
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done by over-riding the CC environment variable used during the build
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to point to one of a few simple shell scripts which may skip part of
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the build.
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<ul>
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<li><tt>non-compiler</tt>: The overhead of the build system itself;
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for Sketch this also includes the time to build/copy various
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non-source code resource files.</li>
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<li><tt>+ driver</tt>: Add execution of the driver, but do not execute any
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commands (by using the -### driver option).</li>
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<li><tt>+ pch gen</tt>: Add generation of PCH files (if used).</li>
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<li><tt>+ syntax</tt>: Add preprocessing, parsing, and semantic checking of
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source files.</li>
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<li><tt>+ IRgen</tt>: Add generation of LLVM IR (gcc has no
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corresponding phase).</li>
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<li><tt>+ codegen</tt>: Add generation of assembler files.</li>
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<li><tt>+ assembler</tt>: Add assembler time to generate .o files.</li>
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<li><tt>+ linker</tt>: Add linker time.</li>
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</ul>
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</p>
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<p>This set of stages is chosen to be approximately additive, that is each
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subsequent stage simply adds some additional processing. The timings measure the
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delta of the given stage from the previous one. For example, the timings
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for <tt>+ syntax</tt> below show the difference of running with <tt>+
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syntax</tt> versus the times for <tt>+ pch gen</tt>. This amounts to a fairly
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accurate measure of only the time to perform preprocessing, parsing, and
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semantic analysis after PCH generation is done.</p>
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<!--*************************************************************************-->
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<h2><a name="timings">Timing Results</a></h2>
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<!--*************************************************************************-->
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<!--=======================================================================-->
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<h3><a name="2009-06-26">2009-06-26</a></h3>
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<!--=======================================================================-->
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<a href="timing-data/2009-06-26/sketch.pdf">
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<img class="img_slide"
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src="timing-data/2009-06-26/sketch.png" alt="Sketch Timings"/>
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</a>
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<a href="timing-data/2009-06-26/176.gcc.pdf">
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<img class="img_slide"
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src="timing-data/2009-06-26/176.gcc.png" alt="176.gcc Timings"/>
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</a>
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</div>
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</body>
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</html>
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