| <html lang="en"> |
| <head> |
| <title>Cross-profiling - Using the GNU Compiler Collection (GCC)</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Using the GNU Compiler Collection (GCC)"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Gcov.html#Gcov" title="Gcov"> |
| <link rel="prev" href="Gcov-Data-Files.html#Gcov-Data-Files" title="Gcov Data Files"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, |
| 2008 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.2 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Funding Free Software'', the Front-Cover |
| Texts being (a) (see below), and with the Back-Cover Texts being (b) |
| (see below). A copy of the license is included in the section entitled |
| ``GNU Free Documentation License''. |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| You have freedom to copy and modify this GNU Manual, like GNU |
| software. Copies published by the Free Software Foundation raise |
| funds for GNU development.--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Cross-profiling"></a> |
| <a name="Cross_002dprofiling"></a> |
| <p> |
| Previous: <a rel="previous" accesskey="p" href="Gcov-Data-Files.html#Gcov-Data-Files">Gcov Data Files</a>, |
| Up: <a rel="up" accesskey="u" href="Gcov.html#Gcov">Gcov</a> |
| <hr> |
| </div> |
| |
| <h3 class="section">10.5 Data file relocation to support cross-profiling</h3> |
| |
| <p>Running the program will cause profile output to be generated. For each |
| source file compiled with <samp><span class="option">-fprofile-arcs</span></samp>, an accompanying <samp><span class="file">.gcda</span></samp> |
| file will be placed in the object file directory. That implicitly requires |
| running the program on the same system as it was built or having the same |
| absolute directory structure on the target system. The program will try |
| to create the needed directory structure, if it is not already present. |
| |
| <p>To support cross-profiling, a program compiled with <samp><span class="option">-fprofile-arcs</span></samp> |
| can relocate the data files based on two environment variables: |
| |
| <ul> |
| <li>GCOV_PREFIX contains the prefix to add to the absolute paths |
| in the object file. Prefix must be absolute as well, otherwise its |
| value is ignored. The default is no prefix. |
| |
| <li>GCOV_PREFIX_STRIP indicates the how many initial directory names to strip off |
| the hardwired absolute paths. Default value is 0. |
| |
| <p><em>Note:</em> GCOV_PREFIX_STRIP has no effect if GCOV_PREFIX is undefined, empty |
| or non-absolute. |
| </ul> |
| |
| <p>For example, if the object file <samp><span class="file">/user/build/foo.o</span></samp> was built with |
| <samp><span class="option">-fprofile-arcs</span></samp>, the final executable will try to create the data file |
| <samp><span class="file">/user/build/foo.gcda</span></samp> when running on the target system. This will |
| fail if the corresponding directory does not exist and it is unable to create |
| it. This can be overcome by, for example, setting the environment as |
| ‘<samp><span class="samp">GCOV_PREFIX=/target/run</span></samp>’ and ‘<samp><span class="samp">GCOV_PREFIX_STRIP=1</span></samp>’. Such a |
| setting will name the data file <samp><span class="file">/target/run/build/foo.gcda</span></samp>. |
| |
| <p>You must move the data files to the expected directory tree in order to |
| use them for profile directed optimizations (<samp><span class="option">--use-profile</span></samp>), or to |
| use the <samp><span class="command">gcov</span></samp> tool. |
| |
| <!-- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, --> |
| <!-- 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 --> |
| <!-- Free Software Foundation, Inc. --> |
| <!-- This is part of the GCC manual. --> |
| <!-- For copying conditions, see the file gcc.texi. --> |
| </body></html> |
| |
