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GCOV-TOOL(1)			       GNU			    GCOV-TOOL(1)

NAME
     gcov-tool - offline gcda profile processing tool

SYNOPSIS
     gcov-tool [-v|--version] [-h|--help]

     gcov-tool merge [merge-options] directory1 directory2
	  [-o|--output directory]
	  [-v|--verbose]
	  [-w|--weight w1,w2]

     gcov-tool merge-stream [merge-stream-options] [file]
	  [-v|--verbose]
	  [-w|--weight w1,w2]

     gcov-tool rewrite [rewrite-options] directory
	  [-n|--normalize long_long_value]
	  [-o|--output directory]
	  [-s|--scale float_or_simple-frac_value]
	  [-v|--verbose]

     gcov-tool overlap [overlap-options] directory1 directory2
	  [-f|--function]
	  [-F|--fullname]
	  [-h|--hotonly]
	  [-o|--object]
	  [-t|--hot_threshold] float
	  [-v|--verbose]

DESCRIPTION
     gcov-tool is an offline tool to process gcc's gcda profile files.

     Current gcov-tool supports the following functionalities:

     *	 merge two sets of profiles with weights.

     *	 read a stream of profiles with associated filenames and merge it with a
	 set of profiles with weights.

     *	 read one set of profile and rewrite profile contents. One can scale or
	 normalize the count values.

     Examples of the use cases for this tool are:

     *	 Collect the profiles for different set of inputs, and use this tool to
	 merge them. One can specify the weight to factor in the relative impor-
	 tance of each input.

     *	 Collect profiles from target systems without a filesystem (freestanding
	 environments).  Merge the collected profiles with associated profiles
	 present on the host system.  One can specify the weight to factor in
	 the relative importance of each input.

     *	 Rewrite the profile after removing a subset of the gcda files, while
	 maintaining the consistency of the summary and the histogram.

     *	 It can also be used to debug or libgcov code as the tools shares the
	 majority code as the runtime library.

     Note that for the merging operation, this profile generated offline may
     contain slight different values from the online merged profile. Here are a
     list of typical differences:

     *	 histogram difference: This offline tool recomputes the histogram after
	 merging the counters. The resulting histogram, therefore, is precise.
	 The online merging does not have this capability -- the histogram is
	 merged from two histograms and the result is an approximation.

     *	 summary checksum difference: Summary checksum uses a CRC32 operation.
	 The value depends on the link list order of gcov-info objects. This or-
	 der is different in gcov-tool from that in the online merge. It's ex-
	 pected to have different summary checksums. It does not really matter
	 as the compiler does not use this checksum anywhere.

     *	 value profile counter values difference: Some counter values for value
	 profile are runtime dependent, like heap addresses. It's normal to see
	 some difference in these kind of counters.

OPTIONS
     -h
     --help
	 Display help about using gcov-tool (on the standard output), and exit
	 without doing any further processing.

     -v
     --version
	 Display the gcov-tool version number (on the standard output), and exit
	 without doing any further processing.

     merge
	 Merge two profile directories.

	 -o directory
	 --output directory
	     Set the output profile directory. Default output directory name is
	     merged_profile.

	 -v
	 --verbose
	     Set the verbose mode.

	 -w w1,w2
	 --weight w1,w2
	     Set the merge weights of the directory1 and directory2, respec-
	     tively. The default weights are 1 for both.

     merge-stream
	 Collect profiles with associated filenames from a gcfn and gcda data
	 stream.  Read the stream from the file specified by file or from stdin.
	 Merge the profiles with associated profiles in the host filesystem.
	 Apply the optional weights while merging profiles.

	 For the generation of a gcfn and gcda data stream on the target system,
	 please have a look at the "__gcov_filename_to_gcfn()" and
	 "__gcov_info_to_gcda()" functions declared in "#include <gcov.h>".

	 -v
	 --verbose
	     Set the verbose mode.

	 -w w1,w2
	 --weight w1,w2
	     Set the merge weights of the profiles from the gcfn and gcda data
	     stream and the associated profiles in the host filesystem, respec-
	     tively.  The default weights are 1 for both.

     rewrite
	 Read the specified profile directory and rewrite to a new directory.

	 -n long_long_value
	 --normalize <long_long_value>
	     Normalize the profile. The specified value is the max counter value
	     in the new profile.

	 -o directory
	 --output directory
	     Set the output profile directory. Default output name is
	     rewrite_profile.

	 -s float_or_simple-frac_value
	 --scale float_or_simple-frac_value
	     Scale the profile counters. The specified value can be in floating
	     point value, or simple fraction value form, such 1, 2, 2/3, and
	     5/3.

	 -v
	 --verbose
	     Set the verbose mode.

     overlap
	 Compute the overlap score between the two specified profile directo-
	 ries.	The overlap score is computed based on the arc profiles. It is
	 defined as the sum of min (p1_counter[i] / p1_sum_all, p2_counter[i] /
	 p2_sum_all), for all arc counter i, where p1_counter[i] and
	 p2_counter[i] are two matched counters and p1_sum_all and p2_sum_all
	 are the sum of counter values in profile 1 and profile 2, respectively.

	 -f
	 --function
	     Print function level overlap score.

	 -F
	 --fullname
	     Print full gcda filename.

	 -h
	 --hotonly
	     Only print info for hot objects/functions.

	 -o
	 --object
	     Print object level overlap score.

	 -t float
	 --hot_threshold <float>
	     Set the threshold for hot counter value.

	 -v
	 --verbose
	     Set the verbose mode.

SEE ALSO
     gpl(7), gfdl(7), fsf-funding(7), gcc(1), gcov(1) and the Info entry for
     gcc.

COPYRIGHT
     Copyright (c) 2014-2024 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 1.3 or any later
     version published by the Free Software Foundation; with the Invariant Sec-
     tions being "GNU General Public License" and "Funding Free Software", the
     Front-Cover texts being (a) (see below), and with the Back-Cover Texts be-
     ing (b) (see below).  A copy of the license is included in the gfdl(7) man
     page.

     (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.

gcc-14.3.1			   2026-03-27			    GCOV-TOOL(1)

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