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95 lines
4.5 KiB
HTML
95 lines
4.5 KiB
HTML
4 years ago
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<html lang="en">
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<head>
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<title>Cross-profiling - Using the GNU Compiler Collection (GCC)</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Using the GNU Compiler Collection (GCC)">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Gcov.html#Gcov" title="Gcov">
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<link rel="prev" href="Gcov-Data-Files.html#Gcov-Data-Files" title="Gcov Data Files">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development.-->
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<style type="text/css"><!--
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pre.display { font-family:inherit }
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span.sansserif { font-family:sans-serif; font-weight:normal; }
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Cross-profiling"></a>
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<a name="Cross_002dprofiling"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Gcov-Data-Files.html#Gcov-Data-Files">Gcov Data Files</a>,
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Up: <a rel="up" accesskey="u" href="Gcov.html#Gcov">Gcov</a>
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<hr>
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</div>
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<h3 class="section">10.5 Data File Relocation to Support Cross-Profiling</h3>
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<p>Running the program will cause profile output to be generated. For each
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source file compiled with <samp><span class="option">-fprofile-arcs</span></samp>, an accompanying <samp><span class="file">.gcda</span></samp>
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file will be placed in the object file directory. That implicitly requires
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running the program on the same system as it was built or having the same
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absolute directory structure on the target system. The program will try
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to create the needed directory structure, if it is not already present.
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<p>To support cross-profiling, a program compiled with <samp><span class="option">-fprofile-arcs</span></samp>
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can relocate the data files based on two environment variables:
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<ul>
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<li>GCOV_PREFIX contains the prefix to add to the absolute paths
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in the object file. Prefix can be absolute, or relative. The
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default is no prefix.
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<li>GCOV_PREFIX_STRIP indicates the how many initial directory names to strip off
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the hardwired absolute paths. Default value is 0.
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<p><em>Note:</em> If GCOV_PREFIX_STRIP is set without GCOV_PREFIX is undefined,
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then a relative path is made out of the hardwired absolute paths.
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</ul>
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<p>For example, if the object file <samp><span class="file">/user/build/foo.o</span></samp> was built with
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<samp><span class="option">-fprofile-arcs</span></samp>, the final executable will try to create the data file
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<samp><span class="file">/user/build/foo.gcda</span></samp> when running on the target system. This will
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fail if the corresponding directory does not exist and it is unable to create
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it. This can be overcome by, for example, setting the environment as
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‘<samp><span class="samp">GCOV_PREFIX=/target/run</span></samp>’ and ‘<samp><span class="samp">GCOV_PREFIX_STRIP=1</span></samp>’. Such a
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setting will name the data file <samp><span class="file">/target/run/build/foo.gcda</span></samp>.
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<p>You must move the data files to the expected directory tree in order to
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use them for profile directed optimizations (<samp><span class="option">--use-profile</span></samp>), or to
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use the <samp><span class="command">gcov</span></samp> tool.
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<!-- Copyright (C) 2014-2015 Free Software Foundation, Inc. -->
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<!-- This is part of the GCC manual. -->
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<!-- For copying conditions, see the file gcc.texi. -->
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</body></html>
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