@c Copyright (C) 1996, 1997, 1999, 2000, 2001,
|
@c Copyright (C) 1996, 1997, 1999, 2000, 2001,
|
@c 2002, 2003, 2004, 2005, 2008 Free Software Foundation, Inc.
|
@c 2002, 2003, 2004, 2005, 2008 Free Software Foundation, Inc.
|
@c This is part of the GCC manual.
|
@c This is part of the GCC manual.
|
@c For copying conditions, see the file gcc.texi.
|
@c For copying conditions, see the file gcc.texi.
|
|
|
@ignore
|
@ignore
|
@c man begin COPYRIGHT
|
@c man begin COPYRIGHT
|
Copyright @copyright{} 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
|
Copyright @copyright{} 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
|
2008 Free Software Foundation, Inc.
|
2008 Free Software Foundation, Inc.
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
Permission is granted to copy, distribute and/or modify this document
|
under the terms of the GNU Free Documentation License, Version 1.2 or
|
under the terms of the GNU Free Documentation License, Version 1.2 or
|
any later version published by the Free Software Foundation; with the
|
any later version published by the Free Software Foundation; with the
|
Invariant Sections being ``GNU General Public License'' and ``Funding
|
Invariant Sections being ``GNU General Public License'' and ``Funding
|
Free Software'', the Front-Cover texts being (a) (see below), and with
|
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
|
the Back-Cover Texts being (b) (see below). A copy of the license is
|
included in the gfdl(7) man page.
|
included in the gfdl(7) man page.
|
|
|
(a) The FSF's Front-Cover Text is:
|
(a) The FSF's Front-Cover Text is:
|
|
|
A GNU Manual
|
A GNU Manual
|
|
|
(b) The FSF's Back-Cover Text is:
|
(b) The FSF's Back-Cover Text is:
|
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
You have freedom to copy and modify this GNU Manual, like GNU
|
software. Copies published by the Free Software Foundation raise
|
software. Copies published by the Free Software Foundation raise
|
funds for GNU development.
|
funds for GNU development.
|
@c man end
|
@c man end
|
@c Set file name and title for the man page.
|
@c Set file name and title for the man page.
|
@setfilename gcov
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@setfilename gcov
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@settitle coverage testing tool
|
@settitle coverage testing tool
|
@end ignore
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@end ignore
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|
|
@node Gcov
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@node Gcov
|
@chapter @command{gcov}---a Test Coverage Program
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@chapter @command{gcov}---a Test Coverage Program
|
|
|
@command{gcov} is a tool you can use in conjunction with GCC to
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@command{gcov} is a tool you can use in conjunction with GCC to
|
test code coverage in your programs.
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test code coverage in your programs.
|
|
|
@menu
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@menu
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* Gcov Intro:: Introduction to gcov.
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* Gcov Intro:: Introduction to gcov.
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* Invoking Gcov:: How to use gcov.
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* Invoking Gcov:: How to use gcov.
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* Gcov and Optimization:: Using gcov with GCC optimization.
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* Gcov and Optimization:: Using gcov with GCC optimization.
|
* Gcov Data Files:: The files used by gcov.
|
* Gcov Data Files:: The files used by gcov.
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* Cross-profiling:: Data file relocation.
|
* Cross-profiling:: Data file relocation.
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@end menu
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@end menu
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|
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@node Gcov Intro
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@node Gcov Intro
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@section Introduction to @command{gcov}
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@section Introduction to @command{gcov}
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@c man begin DESCRIPTION
|
@c man begin DESCRIPTION
|
|
|
@command{gcov} is a test coverage program. Use it in concert with GCC
|
@command{gcov} is a test coverage program. Use it in concert with GCC
|
to analyze your programs to help create more efficient, faster running
|
to analyze your programs to help create more efficient, faster running
|
code and to discover untested parts of your program. You can use
|
code and to discover untested parts of your program. You can use
|
@command{gcov} as a profiling tool to help discover where your
|
@command{gcov} as a profiling tool to help discover where your
|
optimization efforts will best affect your code. You can also use
|
optimization efforts will best affect your code. You can also use
|
@command{gcov} along with the other profiling tool, @command{gprof}, to
|
@command{gcov} along with the other profiling tool, @command{gprof}, to
|
assess which parts of your code use the greatest amount of computing
|
assess which parts of your code use the greatest amount of computing
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time.
|
time.
|
|
|
Profiling tools help you analyze your code's performance. Using a
|
Profiling tools help you analyze your code's performance. Using a
|
profiler such as @command{gcov} or @command{gprof}, you can find out some
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profiler such as @command{gcov} or @command{gprof}, you can find out some
|
basic performance statistics, such as:
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basic performance statistics, such as:
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|
|
@itemize @bullet
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@itemize @bullet
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@item
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@item
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how often each line of code executes
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how often each line of code executes
|
|
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@item
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@item
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what lines of code are actually executed
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what lines of code are actually executed
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|
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@item
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@item
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how much computing time each section of code uses
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how much computing time each section of code uses
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@end itemize
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@end itemize
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|
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Once you know these things about how your code works when compiled, you
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Once you know these things about how your code works when compiled, you
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can look at each module to see which modules should be optimized.
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can look at each module to see which modules should be optimized.
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@command{gcov} helps you determine where to work on optimization.
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@command{gcov} helps you determine where to work on optimization.
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|
|
Software developers also use coverage testing in concert with
|
Software developers also use coverage testing in concert with
|
testsuites, to make sure software is actually good enough for a release.
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testsuites, to make sure software is actually good enough for a release.
|
Testsuites can verify that a program works as expected; a coverage
|
Testsuites can verify that a program works as expected; a coverage
|
program tests to see how much of the program is exercised by the
|
program tests to see how much of the program is exercised by the
|
testsuite. Developers can then determine what kinds of test cases need
|
testsuite. Developers can then determine what kinds of test cases need
|
to be added to the testsuites to create both better testing and a better
|
to be added to the testsuites to create both better testing and a better
|
final product.
|
final product.
|
|
|
You should compile your code without optimization if you plan to use
|
You should compile your code without optimization if you plan to use
|
@command{gcov} because the optimization, by combining some lines of code
|
@command{gcov} because the optimization, by combining some lines of code
|
into one function, may not give you as much information as you need to
|
into one function, may not give you as much information as you need to
|
look for `hot spots' where the code is using a great deal of computer
|
look for `hot spots' where the code is using a great deal of computer
|
time. Likewise, because @command{gcov} accumulates statistics by line (at
|
time. Likewise, because @command{gcov} accumulates statistics by line (at
|
the lowest resolution), it works best with a programming style that
|
the lowest resolution), it works best with a programming style that
|
places only one statement on each line. If you use complicated macros
|
places only one statement on each line. If you use complicated macros
|
that expand to loops or to other control structures, the statistics are
|
that expand to loops or to other control structures, the statistics are
|
less helpful---they only report on the line where the macro call
|
less helpful---they only report on the line where the macro call
|
appears. If your complex macros behave like functions, you can replace
|
appears. If your complex macros behave like functions, you can replace
|
them with inline functions to solve this problem.
|
them with inline functions to solve this problem.
|
|
|
@command{gcov} creates a logfile called @file{@var{sourcefile}.gcov} which
|
@command{gcov} creates a logfile called @file{@var{sourcefile}.gcov} which
|
indicates how many times each line of a source file @file{@var{sourcefile}.c}
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indicates how many times each line of a source file @file{@var{sourcefile}.c}
|
has executed. You can use these logfiles along with @command{gprof} to aid
|
has executed. You can use these logfiles along with @command{gprof} to aid
|
in fine-tuning the performance of your programs. @command{gprof} gives
|
in fine-tuning the performance of your programs. @command{gprof} gives
|
timing information you can use along with the information you get from
|
timing information you can use along with the information you get from
|
@command{gcov}.
|
@command{gcov}.
|
|
|
@command{gcov} works only on code compiled with GCC@. It is not
|
@command{gcov} works only on code compiled with GCC@. It is not
|
compatible with any other profiling or test coverage mechanism.
|
compatible with any other profiling or test coverage mechanism.
|
|
|
@c man end
|
@c man end
|
|
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@node Invoking Gcov
|
@node Invoking Gcov
|
@section Invoking @command{gcov}
|
@section Invoking @command{gcov}
|
|
|
@smallexample
|
@smallexample
|
gcov @r{[}@var{options}@r{]} @var{sourcefiles}
|
gcov @r{[}@var{options}@r{]} @var{sourcefiles}
|
@end smallexample
|
@end smallexample
|
|
|
@command{gcov} accepts the following options:
|
@command{gcov} accepts the following options:
|
|
|
@ignore
|
@ignore
|
@c man begin SYNOPSIS
|
@c man begin SYNOPSIS
|
gcov [@option{-v}|@option{--version}] [@option{-h}|@option{--help}]
|
gcov [@option{-v}|@option{--version}] [@option{-h}|@option{--help}]
|
[@option{-a}|@option{--all-blocks}]
|
[@option{-a}|@option{--all-blocks}]
|
[@option{-b}|@option{--branch-probabilities}]
|
[@option{-b}|@option{--branch-probabilities}]
|
[@option{-c}|@option{--branch-counts}]
|
[@option{-c}|@option{--branch-counts}]
|
[@option{-n}|@option{--no-output}]
|
[@option{-n}|@option{--no-output}]
|
[@option{-l}|@option{--long-file-names}]
|
[@option{-l}|@option{--long-file-names}]
|
[@option{-p}|@option{--preserve-paths}]
|
[@option{-p}|@option{--preserve-paths}]
|
[@option{-f}|@option{--function-summaries}]
|
[@option{-f}|@option{--function-summaries}]
|
[@option{-o}|@option{--object-directory} @var{directory|file}] @var{sourcefiles}
|
[@option{-o}|@option{--object-directory} @var{directory|file}] @var{sourcefiles}
|
[@option{-u}|@option{--unconditional-branches}]
|
[@option{-u}|@option{--unconditional-branches}]
|
@c man end
|
@c man end
|
@c man begin SEEALSO
|
@c man begin SEEALSO
|
gpl(7), gfdl(7), fsf-funding(7), gcc(1) and the Info entry for @file{gcc}.
|
gpl(7), gfdl(7), fsf-funding(7), gcc(1) and the Info entry for @file{gcc}.
|
@c man end
|
@c man end
|
@end ignore
|
@end ignore
|
|
|
@c man begin OPTIONS
|
@c man begin OPTIONS
|
@table @gcctabopt
|
@table @gcctabopt
|
@item -h
|
@item -h
|
@itemx --help
|
@itemx --help
|
Display help about using @command{gcov} (on the standard output), and
|
Display help about using @command{gcov} (on the standard output), and
|
exit without doing any further processing.
|
exit without doing any further processing.
|
|
|
@item -v
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@item -v
|
@itemx --version
|
@itemx --version
|
Display the @command{gcov} version number (on the standard output),
|
Display the @command{gcov} version number (on the standard output),
|
and exit without doing any further processing.
|
and exit without doing any further processing.
|
|
|
@item -a
|
@item -a
|
@itemx --all-blocks
|
@itemx --all-blocks
|
Write individual execution counts for every basic block. Normally gcov
|
Write individual execution counts for every basic block. Normally gcov
|
outputs execution counts only for the main blocks of a line. With this
|
outputs execution counts only for the main blocks of a line. With this
|
option you can determine if blocks within a single line are not being
|
option you can determine if blocks within a single line are not being
|
executed.
|
executed.
|
|
|
@item -b
|
@item -b
|
@itemx --branch-probabilities
|
@itemx --branch-probabilities
|
Write branch frequencies to the output file, and write branch summary
|
Write branch frequencies to the output file, and write branch summary
|
info to the standard output. This option allows you to see how often
|
info to the standard output. This option allows you to see how often
|
each branch in your program was taken. Unconditional branches will not
|
each branch in your program was taken. Unconditional branches will not
|
be shown, unless the @option{-u} option is given.
|
be shown, unless the @option{-u} option is given.
|
|
|
@item -c
|
@item -c
|
@itemx --branch-counts
|
@itemx --branch-counts
|
Write branch frequencies as the number of branches taken, rather than
|
Write branch frequencies as the number of branches taken, rather than
|
the percentage of branches taken.
|
the percentage of branches taken.
|
|
|
@item -n
|
@item -n
|
@itemx --no-output
|
@itemx --no-output
|
Do not create the @command{gcov} output file.
|
Do not create the @command{gcov} output file.
|
|
|
@item -l
|
@item -l
|
@itemx --long-file-names
|
@itemx --long-file-names
|
Create long file names for included source files. For example, if the
|
Create long file names for included source files. For example, if the
|
header file @file{x.h} contains code, and was included in the file
|
header file @file{x.h} contains code, and was included in the file
|
@file{a.c}, then running @command{gcov} on the file @file{a.c} will produce
|
@file{a.c}, then running @command{gcov} on the file @file{a.c} will produce
|
an output file called @file{a.c##x.h.gcov} instead of @file{x.h.gcov}.
|
an output file called @file{a.c##x.h.gcov} instead of @file{x.h.gcov}.
|
This can be useful if @file{x.h} is included in multiple source
|
This can be useful if @file{x.h} is included in multiple source
|
files. If you use the @samp{-p} option, both the including and
|
files. If you use the @samp{-p} option, both the including and
|
included file names will be complete path names.
|
included file names will be complete path names.
|
|
|
@item -p
|
@item -p
|
@itemx --preserve-paths
|
@itemx --preserve-paths
|
Preserve complete path information in the names of generated
|
Preserve complete path information in the names of generated
|
@file{.gcov} files. Without this option, just the filename component is
|
@file{.gcov} files. Without this option, just the filename component is
|
used. With this option, all directories are used, with @samp{/} characters
|
used. With this option, all directories are used, with @samp{/} characters
|
translated to @samp{#} characters, @file{.} directory components
|
translated to @samp{#} characters, @file{.} directory components
|
removed and @file{..}
|
removed and @file{..}
|
components renamed to @samp{^}. This is useful if sourcefiles are in several
|
components renamed to @samp{^}. This is useful if sourcefiles are in several
|
different directories. It also affects the @samp{-l} option.
|
different directories. It also affects the @samp{-l} option.
|
|
|
@item -f
|
@item -f
|
@itemx --function-summaries
|
@itemx --function-summaries
|
Output summaries for each function in addition to the file level summary.
|
Output summaries for each function in addition to the file level summary.
|
|
|
@item -o @var{directory|file}
|
@item -o @var{directory|file}
|
@itemx --object-directory @var{directory}
|
@itemx --object-directory @var{directory}
|
@itemx --object-file @var{file}
|
@itemx --object-file @var{file}
|
Specify either the directory containing the gcov data files, or the
|
Specify either the directory containing the gcov data files, or the
|
object path name. The @file{.gcno}, and
|
object path name. The @file{.gcno}, and
|
@file{.gcda} data files are searched for using this option. If a directory
|
@file{.gcda} data files are searched for using this option. If a directory
|
is specified, the data files are in that directory and named after the
|
is specified, the data files are in that directory and named after the
|
source file name, without its extension. If a file is specified here,
|
source file name, without its extension. If a file is specified here,
|
the data files are named after that file, without its extension. If this
|
the data files are named after that file, without its extension. If this
|
option is not supplied, it defaults to the current directory.
|
option is not supplied, it defaults to the current directory.
|
|
|
@item -u
|
@item -u
|
@itemx --unconditional-branches
|
@itemx --unconditional-branches
|
When branch probabilities are given, include those of unconditional branches.
|
When branch probabilities are given, include those of unconditional branches.
|
Unconditional branches are normally not interesting.
|
Unconditional branches are normally not interesting.
|
|
|
@end table
|
@end table
|
|
|
@command{gcov} should be run with the current directory the same as that
|
@command{gcov} should be run with the current directory the same as that
|
when you invoked the compiler. Otherwise it will not be able to locate
|
when you invoked the compiler. Otherwise it will not be able to locate
|
the source files. @command{gcov} produces files called
|
the source files. @command{gcov} produces files called
|
@file{@var{mangledname}.gcov} in the current directory. These contain
|
@file{@var{mangledname}.gcov} in the current directory. These contain
|
the coverage information of the source file they correspond to.
|
the coverage information of the source file they correspond to.
|
One @file{.gcov} file is produced for each source file containing code,
|
One @file{.gcov} file is produced for each source file containing code,
|
which was compiled to produce the data files. The @var{mangledname} part
|
which was compiled to produce the data files. The @var{mangledname} part
|
of the output file name is usually simply the source file name, but can
|
of the output file name is usually simply the source file name, but can
|
be something more complicated if the @samp{-l} or @samp{-p} options are
|
be something more complicated if the @samp{-l} or @samp{-p} options are
|
given. Refer to those options for details.
|
given. Refer to those options for details.
|
|
|
The @file{.gcov} files contain the @samp{:} separated fields along with
|
The @file{.gcov} files contain the @samp{:} separated fields along with
|
program source code. The format is
|
program source code. The format is
|
|
|
@smallexample
|
@smallexample
|
@var{execution_count}:@var{line_number}:@var{source line text}
|
@var{execution_count}:@var{line_number}:@var{source line text}
|
@end smallexample
|
@end smallexample
|
|
|
Additional block information may succeed each line, when requested by
|
Additional block information may succeed each line, when requested by
|
command line option. The @var{execution_count} is @samp{-} for lines
|
command line option. The @var{execution_count} is @samp{-} for lines
|
containing no code and @samp{#####} for lines which were never executed.
|
containing no code and @samp{#####} for lines which were never executed.
|
Some lines of information at the start have @var{line_number} of zero.
|
Some lines of information at the start have @var{line_number} of zero.
|
|
|
The preamble lines are of the form
|
The preamble lines are of the form
|
|
|
@smallexample
|
@smallexample
|
-:0:@var{tag}:@var{value}
|
-:0:@var{tag}:@var{value}
|
@end smallexample
|
@end smallexample
|
|
|
The ordering and number of these preamble lines will be augmented as
|
The ordering and number of these preamble lines will be augmented as
|
@command{gcov} development progresses --- do not rely on them remaining
|
@command{gcov} development progresses --- do not rely on them remaining
|
unchanged. Use @var{tag} to locate a particular preamble line.
|
unchanged. Use @var{tag} to locate a particular preamble line.
|
|
|
The additional block information is of the form
|
The additional block information is of the form
|
|
|
@smallexample
|
@smallexample
|
@var{tag} @var{information}
|
@var{tag} @var{information}
|
@end smallexample
|
@end smallexample
|
|
|
The @var{information} is human readable, but designed to be simple
|
The @var{information} is human readable, but designed to be simple
|
enough for machine parsing too.
|
enough for machine parsing too.
|
|
|
When printing percentages, 0% and 100% are only printed when the values
|
When printing percentages, 0% and 100% are only printed when the values
|
are @emph{exactly} 0% and 100% respectively. Other values which would
|
are @emph{exactly} 0% and 100% respectively. Other values which would
|
conventionally be rounded to 0% or 100% are instead printed as the
|
conventionally be rounded to 0% or 100% are instead printed as the
|
nearest non-boundary value.
|
nearest non-boundary value.
|
|
|
When using @command{gcov}, you must first compile your program with two
|
When using @command{gcov}, you must first compile your program with two
|
special GCC options: @samp{-fprofile-arcs -ftest-coverage}.
|
special GCC options: @samp{-fprofile-arcs -ftest-coverage}.
|
This tells the compiler to generate additional information needed by
|
This tells the compiler to generate additional information needed by
|
gcov (basically a flow graph of the program) and also includes
|
gcov (basically a flow graph of the program) and also includes
|
additional code in the object files for generating the extra profiling
|
additional code in the object files for generating the extra profiling
|
information needed by gcov. These additional files are placed in the
|
information needed by gcov. These additional files are placed in the
|
directory where the object file is located.
|
directory where the object file is located.
|
|
|
Running the program will cause profile output to be generated. For each
|
Running the program will cause profile output to be generated. For each
|
source file compiled with @option{-fprofile-arcs}, an accompanying
|
source file compiled with @option{-fprofile-arcs}, an accompanying
|
@file{.gcda} file will be placed in the object file directory.
|
@file{.gcda} file will be placed in the object file directory.
|
|
|
Running @command{gcov} with your program's source file names as arguments
|
Running @command{gcov} with your program's source file names as arguments
|
will now produce a listing of the code along with frequency of execution
|
will now produce a listing of the code along with frequency of execution
|
for each line. For example, if your program is called @file{tmp.c}, this
|
for each line. For example, if your program is called @file{tmp.c}, this
|
is what you see when you use the basic @command{gcov} facility:
|
is what you see when you use the basic @command{gcov} facility:
|
|
|
@smallexample
|
@smallexample
|
$ gcc -fprofile-arcs -ftest-coverage tmp.c
|
$ gcc -fprofile-arcs -ftest-coverage tmp.c
|
$ a.out
|
$ a.out
|
$ gcov tmp.c
|
$ gcov tmp.c
|
90.00% of 10 source lines executed in file tmp.c
|
90.00% of 10 source lines executed in file tmp.c
|
Creating tmp.c.gcov.
|
Creating tmp.c.gcov.
|
@end smallexample
|
@end smallexample
|
|
|
The file @file{tmp.c.gcov} contains output from @command{gcov}.
|
The file @file{tmp.c.gcov} contains output from @command{gcov}.
|
Here is a sample:
|
Here is a sample:
|
|
|
@smallexample
|
@smallexample
|
-: 0:Source:tmp.c
|
-: 0:Source:tmp.c
|
-: 0:Graph:tmp.gcno
|
-: 0:Graph:tmp.gcno
|
-: 0:Data:tmp.gcda
|
-: 0:Data:tmp.gcda
|
-: 0:Runs:1
|
-: 0:Runs:1
|
-: 0:Programs:1
|
-: 0:Programs:1
|
-: 1:#include <stdio.h>
|
-: 1:#include <stdio.h>
|
-: 2:
|
-: 2:
|
-: 3:int main (void)
|
-: 3:int main (void)
|
1: 4:@{
|
1: 4:@{
|
1: 5: int i, total;
|
1: 5: int i, total;
|
-: 6:
|
-: 6:
|
1: 7: total = 0;
|
1: 7: total = 0;
|
-: 8:
|
-: 8:
|
11: 9: for (i = 0; i < 10; i++)
|
11: 9: for (i = 0; i < 10; i++)
|
10: 10: total += i;
|
10: 10: total += i;
|
-: 11:
|
-: 11:
|
1: 12: if (total != 45)
|
1: 12: if (total != 45)
|
#####: 13: printf ("Failure\n");
|
#####: 13: printf ("Failure\n");
|
-: 14: else
|
-: 14: else
|
1: 15: printf ("Success\n");
|
1: 15: printf ("Success\n");
|
1: 16: return 0;
|
1: 16: return 0;
|
-: 17:@}
|
-: 17:@}
|
@end smallexample
|
@end smallexample
|
|
|
When you use the @option{-a} option, you will get individual block
|
When you use the @option{-a} option, you will get individual block
|
counts, and the output looks like this:
|
counts, and the output looks like this:
|
|
|
@smallexample
|
@smallexample
|
-: 0:Source:tmp.c
|
-: 0:Source:tmp.c
|
-: 0:Graph:tmp.gcno
|
-: 0:Graph:tmp.gcno
|
-: 0:Data:tmp.gcda
|
-: 0:Data:tmp.gcda
|
-: 0:Runs:1
|
-: 0:Runs:1
|
-: 0:Programs:1
|
-: 0:Programs:1
|
-: 1:#include <stdio.h>
|
-: 1:#include <stdio.h>
|
-: 2:
|
-: 2:
|
-: 3:int main (void)
|
-: 3:int main (void)
|
1: 4:@{
|
1: 4:@{
|
1: 4-block 0
|
1: 4-block 0
|
1: 5: int i, total;
|
1: 5: int i, total;
|
-: 6:
|
-: 6:
|
1: 7: total = 0;
|
1: 7: total = 0;
|
-: 8:
|
-: 8:
|
11: 9: for (i = 0; i < 10; i++)
|
11: 9: for (i = 0; i < 10; i++)
|
11: 9-block 0
|
11: 9-block 0
|
10: 10: total += i;
|
10: 10: total += i;
|
10: 10-block 0
|
10: 10-block 0
|
-: 11:
|
-: 11:
|
1: 12: if (total != 45)
|
1: 12: if (total != 45)
|
1: 12-block 0
|
1: 12-block 0
|
#####: 13: printf ("Failure\n");
|
#####: 13: printf ("Failure\n");
|
$$$$$: 13-block 0
|
$$$$$: 13-block 0
|
-: 14: else
|
-: 14: else
|
1: 15: printf ("Success\n");
|
1: 15: printf ("Success\n");
|
1: 15-block 0
|
1: 15-block 0
|
1: 16: return 0;
|
1: 16: return 0;
|
1: 16-block 0
|
1: 16-block 0
|
-: 17:@}
|
-: 17:@}
|
@end smallexample
|
@end smallexample
|
|
|
In this mode, each basic block is only shown on one line -- the last
|
In this mode, each basic block is only shown on one line -- the last
|
line of the block. A multi-line block will only contribute to the
|
line of the block. A multi-line block will only contribute to the
|
execution count of that last line, and other lines will not be shown
|
execution count of that last line, and other lines will not be shown
|
to contain code, unless previous blocks end on those lines.
|
to contain code, unless previous blocks end on those lines.
|
The total execution count of a line is shown and subsequent lines show
|
The total execution count of a line is shown and subsequent lines show
|
the execution counts for individual blocks that end on that line. After each
|
the execution counts for individual blocks that end on that line. After each
|
block, the branch and call counts of the block will be shown, if the
|
block, the branch and call counts of the block will be shown, if the
|
@option{-b} option is given.
|
@option{-b} option is given.
|
|
|
Because of the way GCC instruments calls, a call count can be shown
|
Because of the way GCC instruments calls, a call count can be shown
|
after a line with no individual blocks.
|
after a line with no individual blocks.
|
As you can see, line 13 contains a basic block that was not executed.
|
As you can see, line 13 contains a basic block that was not executed.
|
|
|
@need 450
|
@need 450
|
When you use the @option{-b} option, your output looks like this:
|
When you use the @option{-b} option, your output looks like this:
|
|
|
@smallexample
|
@smallexample
|
$ gcov -b tmp.c
|
$ gcov -b tmp.c
|
90.00% of 10 source lines executed in file tmp.c
|
90.00% of 10 source lines executed in file tmp.c
|
80.00% of 5 branches executed in file tmp.c
|
80.00% of 5 branches executed in file tmp.c
|
80.00% of 5 branches taken at least once in file tmp.c
|
80.00% of 5 branches taken at least once in file tmp.c
|
50.00% of 2 calls executed in file tmp.c
|
50.00% of 2 calls executed in file tmp.c
|
Creating tmp.c.gcov.
|
Creating tmp.c.gcov.
|
@end smallexample
|
@end smallexample
|
|
|
Here is a sample of a resulting @file{tmp.c.gcov} file:
|
Here is a sample of a resulting @file{tmp.c.gcov} file:
|
|
|
@smallexample
|
@smallexample
|
-: 0:Source:tmp.c
|
-: 0:Source:tmp.c
|
-: 0:Graph:tmp.gcno
|
-: 0:Graph:tmp.gcno
|
-: 0:Data:tmp.gcda
|
-: 0:Data:tmp.gcda
|
-: 0:Runs:1
|
-: 0:Runs:1
|
-: 0:Programs:1
|
-: 0:Programs:1
|
-: 1:#include <stdio.h>
|
-: 1:#include <stdio.h>
|
-: 2:
|
-: 2:
|
-: 3:int main (void)
|
-: 3:int main (void)
|
function main called 1 returned 1 blocks executed 75%
|
function main called 1 returned 1 blocks executed 75%
|
1: 4:@{
|
1: 4:@{
|
1: 5: int i, total;
|
1: 5: int i, total;
|
-: 6:
|
-: 6:
|
1: 7: total = 0;
|
1: 7: total = 0;
|
-: 8:
|
-: 8:
|
11: 9: for (i = 0; i < 10; i++)
|
11: 9: for (i = 0; i < 10; i++)
|
branch 0 taken 91% (fallthrough)
|
branch 0 taken 91% (fallthrough)
|
branch 1 taken 9%
|
branch 1 taken 9%
|
10: 10: total += i;
|
10: 10: total += i;
|
-: 11:
|
-: 11:
|
1: 12: if (total != 45)
|
1: 12: if (total != 45)
|
branch 0 taken 0% (fallthrough)
|
branch 0 taken 0% (fallthrough)
|
branch 1 taken 100%
|
branch 1 taken 100%
|
#####: 13: printf ("Failure\n");
|
#####: 13: printf ("Failure\n");
|
call 0 never executed
|
call 0 never executed
|
-: 14: else
|
-: 14: else
|
1: 15: printf ("Success\n");
|
1: 15: printf ("Success\n");
|
call 0 called 1 returned 100%
|
call 0 called 1 returned 100%
|
1: 16: return 0;
|
1: 16: return 0;
|
-: 17:@}
|
-: 17:@}
|
@end smallexample
|
@end smallexample
|
|
|
For each function, a line is printed showing how many times the function
|
For each function, a line is printed showing how many times the function
|
is called, how many times it returns and what percentage of the
|
is called, how many times it returns and what percentage of the
|
function's blocks were executed.
|
function's blocks were executed.
|
|
|
For each basic block, a line is printed after the last line of the basic
|
For each basic block, a line is printed after the last line of the basic
|
block describing the branch or call that ends the basic block. There can
|
block describing the branch or call that ends the basic block. There can
|
be multiple branches and calls listed for a single source line if there
|
be multiple branches and calls listed for a single source line if there
|
are multiple basic blocks that end on that line. In this case, the
|
are multiple basic blocks that end on that line. In this case, the
|
branches and calls are each given a number. There is no simple way to map
|
branches and calls are each given a number. There is no simple way to map
|
these branches and calls back to source constructs. In general, though,
|
these branches and calls back to source constructs. In general, though,
|
the lowest numbered branch or call will correspond to the leftmost construct
|
the lowest numbered branch or call will correspond to the leftmost construct
|
on the source line.
|
on the source line.
|
|
|
For a branch, if it was executed at least once, then a percentage
|
For a branch, if it was executed at least once, then a percentage
|
indicating the number of times the branch was taken divided by the
|
indicating the number of times the branch was taken divided by the
|
number of times the branch was executed will be printed. Otherwise, the
|
number of times the branch was executed will be printed. Otherwise, the
|
message ``never executed'' is printed.
|
message ``never executed'' is printed.
|
|
|
For a call, if it was executed at least once, then a percentage
|
For a call, if it was executed at least once, then a percentage
|
indicating the number of times the call returned divided by the number
|
indicating the number of times the call returned divided by the number
|
of times the call was executed will be printed. This will usually be
|
of times the call was executed will be printed. This will usually be
|
100%, but may be less for functions that call @code{exit} or @code{longjmp},
|
100%, but may be less for functions that call @code{exit} or @code{longjmp},
|
and thus may not return every time they are called.
|
and thus may not return every time they are called.
|
|
|
The execution counts are cumulative. If the example program were
|
The execution counts are cumulative. If the example program were
|
executed again without removing the @file{.gcda} file, the count for the
|
executed again without removing the @file{.gcda} file, the count for the
|
number of times each line in the source was executed would be added to
|
number of times each line in the source was executed would be added to
|
the results of the previous run(s). This is potentially useful in
|
the results of the previous run(s). This is potentially useful in
|
several ways. For example, it could be used to accumulate data over a
|
several ways. For example, it could be used to accumulate data over a
|
number of program runs as part of a test verification suite, or to
|
number of program runs as part of a test verification suite, or to
|
provide more accurate long-term information over a large number of
|
provide more accurate long-term information over a large number of
|
program runs.
|
program runs.
|
|
|
The data in the @file{.gcda} files is saved immediately before the program
|
The data in the @file{.gcda} files is saved immediately before the program
|
exits. For each source file compiled with @option{-fprofile-arcs}, the
|
exits. For each source file compiled with @option{-fprofile-arcs}, the
|
profiling code first attempts to read in an existing @file{.gcda} file; if
|
profiling code first attempts to read in an existing @file{.gcda} file; if
|
the file doesn't match the executable (differing number of basic block
|
the file doesn't match the executable (differing number of basic block
|
counts) it will ignore the contents of the file. It then adds in the
|
counts) it will ignore the contents of the file. It then adds in the
|
new execution counts and finally writes the data to the file.
|
new execution counts and finally writes the data to the file.
|
|
|
@node Gcov and Optimization
|
@node Gcov and Optimization
|
@section Using @command{gcov} with GCC Optimization
|
@section Using @command{gcov} with GCC Optimization
|
|
|
If you plan to use @command{gcov} to help optimize your code, you must
|
If you plan to use @command{gcov} to help optimize your code, you must
|
first compile your program with two special GCC options:
|
first compile your program with two special GCC options:
|
@samp{-fprofile-arcs -ftest-coverage}. Aside from that, you can use any
|
@samp{-fprofile-arcs -ftest-coverage}. Aside from that, you can use any
|
other GCC options; but if you want to prove that every single line
|
other GCC options; but if you want to prove that every single line
|
in your program was executed, you should not compile with optimization
|
in your program was executed, you should not compile with optimization
|
at the same time. On some machines the optimizer can eliminate some
|
at the same time. On some machines the optimizer can eliminate some
|
simple code lines by combining them with other lines. For example, code
|
simple code lines by combining them with other lines. For example, code
|
like this:
|
like this:
|
|
|
@smallexample
|
@smallexample
|
if (a != b)
|
if (a != b)
|
c = 1;
|
c = 1;
|
else
|
else
|
c = 0;
|
c = 0;
|
@end smallexample
|
@end smallexample
|
|
|
@noindent
|
@noindent
|
can be compiled into one instruction on some machines. In this case,
|
can be compiled into one instruction on some machines. In this case,
|
there is no way for @command{gcov} to calculate separate execution counts
|
there is no way for @command{gcov} to calculate separate execution counts
|
for each line because there isn't separate code for each line. Hence
|
for each line because there isn't separate code for each line. Hence
|
the @command{gcov} output looks like this if you compiled the program with
|
the @command{gcov} output looks like this if you compiled the program with
|
optimization:
|
optimization:
|
|
|
@smallexample
|
@smallexample
|
100: 12:if (a != b)
|
100: 12:if (a != b)
|
100: 13: c = 1;
|
100: 13: c = 1;
|
100: 14:else
|
100: 14:else
|
100: 15: c = 0;
|
100: 15: c = 0;
|
@end smallexample
|
@end smallexample
|
|
|
The output shows that this block of code, combined by optimization,
|
The output shows that this block of code, combined by optimization,
|
executed 100 times. In one sense this result is correct, because there
|
executed 100 times. In one sense this result is correct, because there
|
was only one instruction representing all four of these lines. However,
|
was only one instruction representing all four of these lines. However,
|
the output does not indicate how many times the result was 0 and how
|
the output does not indicate how many times the result was 0 and how
|
many times the result was 1.
|
many times the result was 1.
|
|
|
Inlineable functions can create unexpected line counts. Line counts are
|
Inlineable functions can create unexpected line counts. Line counts are
|
shown for the source code of the inlineable function, but what is shown
|
shown for the source code of the inlineable function, but what is shown
|
depends on where the function is inlined, or if it is not inlined at all.
|
depends on where the function is inlined, or if it is not inlined at all.
|
|
|
If the function is not inlined, the compiler must emit an out of line
|
If the function is not inlined, the compiler must emit an out of line
|
copy of the function, in any object file that needs it. If
|
copy of the function, in any object file that needs it. If
|
@file{fileA.o} and @file{fileB.o} both contain out of line bodies of a
|
@file{fileA.o} and @file{fileB.o} both contain out of line bodies of a
|
particular inlineable function, they will also both contain coverage
|
particular inlineable function, they will also both contain coverage
|
counts for that function. When @file{fileA.o} and @file{fileB.o} are
|
counts for that function. When @file{fileA.o} and @file{fileB.o} are
|
linked together, the linker will, on many systems, select one of those
|
linked together, the linker will, on many systems, select one of those
|
out of line bodies for all calls to that function, and remove or ignore
|
out of line bodies for all calls to that function, and remove or ignore
|
the other. Unfortunately, it will not remove the coverage counters for
|
the other. Unfortunately, it will not remove the coverage counters for
|
the unused function body. Hence when instrumented, all but one use of
|
the unused function body. Hence when instrumented, all but one use of
|
that function will show zero counts.
|
that function will show zero counts.
|
|
|
If the function is inlined in several places, the block structure in
|
If the function is inlined in several places, the block structure in
|
each location might not be the same. For instance, a condition might
|
each location might not be the same. For instance, a condition might
|
now be calculable at compile time in some instances. Because the
|
now be calculable at compile time in some instances. Because the
|
coverage of all the uses of the inline function will be shown for the
|
coverage of all the uses of the inline function will be shown for the
|
same source lines, the line counts themselves might seem inconsistent.
|
same source lines, the line counts themselves might seem inconsistent.
|
|
|
@c man end
|
@c man end
|
|
|
@node Gcov Data Files
|
@node Gcov Data Files
|
@section Brief description of @command{gcov} data files
|
@section Brief description of @command{gcov} data files
|
|
|
@command{gcov} uses two files for profiling. The names of these files
|
@command{gcov} uses two files for profiling. The names of these files
|
are derived from the original @emph{object} file by substituting the
|
are derived from the original @emph{object} file by substituting the
|
file suffix with either @file{.gcno}, or @file{.gcda}. All of these files
|
file suffix with either @file{.gcno}, or @file{.gcda}. All of these files
|
are placed in the same directory as the object file, and contain data
|
are placed in the same directory as the object file, and contain data
|
stored in a platform-independent format.
|
stored in a platform-independent format.
|
|
|
The @file{.gcno} file is generated when the source file is compiled with
|
The @file{.gcno} file is generated when the source file is compiled with
|
the GCC @option{-ftest-coverage} option. It contains information to
|
the GCC @option{-ftest-coverage} option. It contains information to
|
reconstruct the basic block graphs and assign source line numbers to
|
reconstruct the basic block graphs and assign source line numbers to
|
blocks.
|
blocks.
|
|
|
The @file{.gcda} file is generated when a program containing object files
|
The @file{.gcda} file is generated when a program containing object files
|
built with the GCC @option{-fprofile-arcs} option is executed. A
|
built with the GCC @option{-fprofile-arcs} option is executed. A
|
separate @file{.gcda} file is created for each object file compiled with
|
separate @file{.gcda} file is created for each object file compiled with
|
this option. It contains arc transition counts, and some summary
|
this option. It contains arc transition counts, and some summary
|
information.
|
information.
|
|
|
The full details of the file format is specified in @file{gcov-io.h},
|
The full details of the file format is specified in @file{gcov-io.h},
|
and functions provided in that header file should be used to access the
|
and functions provided in that header file should be used to access the
|
coverage files.
|
coverage files.
|
|
|
@node Cross-profiling
|
@node Cross-profiling
|
@section Data file relocation to support cross-profiling
|
@section Data file relocation to support cross-profiling
|
|
|
Running the program will cause profile output to be generated. For each
|
Running the program will cause profile output to be generated. For each
|
source file compiled with @option{-fprofile-arcs}, an accompanying @file{.gcda}
|
source file compiled with @option{-fprofile-arcs}, an accompanying @file{.gcda}
|
file will be placed in the object file directory. That implicitly requires
|
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
|
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
|
absolute directory structure on the target system. The program will try
|
to create the needed directory structure, if it is not already present.
|
to create the needed directory structure, if it is not already present.
|
|
|
To support cross-profiling, a program compiled with @option{-fprofile-arcs}
|
To support cross-profiling, a program compiled with @option{-fprofile-arcs}
|
can relocate the data files based on two environment variables:
|
can relocate the data files based on two environment variables:
|
|
|
@itemize @bullet
|
@itemize @bullet
|
@item
|
@item
|
GCOV_PREFIX contains the prefix to add to the absolute paths
|
GCOV_PREFIX contains the prefix to add to the absolute paths
|
in the object file. Prefix must be absolute as well, otherwise its
|
in the object file. Prefix must be absolute as well, otherwise its
|
value is ignored. The default is no prefix.
|
value is ignored. The default is no prefix.
|
|
|
@item
|
@item
|
GCOV_PREFIX_STRIP indicates the how many initial directory names to strip off
|
GCOV_PREFIX_STRIP indicates the how many initial directory names to strip off
|
the hardwired absolute paths. Default value is 0.
|
the hardwired absolute paths. Default value is 0.
|
|
|
@emph{Note:} GCOV_PREFIX_STRIP has no effect if GCOV_PREFIX is undefined, empty
|
@emph{Note:} GCOV_PREFIX_STRIP has no effect if GCOV_PREFIX is undefined, empty
|
or non-absolute.
|
or non-absolute.
|
@end itemize
|
@end itemize
|
|
|
For example, if the object file @file{/user/build/foo.o} was built with
|
For example, if the object file @file{/user/build/foo.o} was built with
|
@option{-fprofile-arcs}, the final executable will try to create the data file
|
@option{-fprofile-arcs}, the final executable will try to create the data file
|
@file{/user/build/foo.gcda} when running on the target system. This will
|
@file{/user/build/foo.gcda} when running on the target system. This will
|
fail if the corresponding directory does not exist and it is unable to create
|
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
|
it. This can be overcome by, for example, setting the environment as
|
@samp{GCOV_PREFIX=/target/run} and @samp{GCOV_PREFIX_STRIP=1}. Such a
|
@samp{GCOV_PREFIX=/target/run} and @samp{GCOV_PREFIX_STRIP=1}. Such a
|
setting will name the data file @file{/target/run/build/foo.gcda}.
|
setting will name the data file @file{/target/run/build/foo.gcda}.
|
|
|
You must move the data files to the expected directory tree in order to
|
You must move the data files to the expected directory tree in order to
|
use them for profile directed optimizations (@option{--use-profile}), or to
|
use them for profile directed optimizations (@option{--use-profile}), or to
|
use the @command{gcov} tool.
|
use the @command{gcov} tool.
|
|
|
