-@c Copyright (C) 1996, 1997, 1999, 2000, 2001,
-@c 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+@c Copyright (C) 1996-2020 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@ignore
@c man begin COPYRIGHT
-Copyright @copyright{} 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005
-Free Software Foundation, Inc.
+Copyright @copyright{} 1996-2020 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
+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 Sections being ``GNU General Public License'' and ``Funding
Free Software'', the Front-Cover texts being (a) (see below), and with
test code coverage in your programs.
@menu
-* Gcov Intro:: Introduction to gcov.
-* Invoking Gcov:: How to use gcov.
+* Gcov Intro:: Introduction to gcov.
+* Invoking Gcov:: How to use gcov.
* Gcov and Optimization:: Using gcov with GCC optimization.
* Gcov Data Files:: The files used by gcov.
* Cross-profiling:: Data file relocation.
@section Invoking @command{gcov}
@smallexample
-gcov @r{[}@var{options}@r{]} @var{sourcefiles}
+gcov @r{[}@var{options}@r{]} @var{files}
@end smallexample
@command{gcov} accepts the following options:
[@option{-a}|@option{--all-blocks}]
[@option{-b}|@option{--branch-probabilities}]
[@option{-c}|@option{--branch-counts}]
- [@option{-n}|@option{--no-output}]
+ [@option{-d}|@option{--display-progress}]
+ [@option{-f}|@option{--function-summaries}]
+ [@option{-i}|@option{--json-format}]
+ [@option{-j}|@option{--human-readable}]
+ [@option{-k}|@option{--use-colors}]
[@option{-l}|@option{--long-file-names}]
+ [@option{-m}|@option{--demangled-names}]
+ [@option{-n}|@option{--no-output}]
+ [@option{-o}|@option{--object-directory} @var{directory|file}]
[@option{-p}|@option{--preserve-paths}]
- [@option{-f}|@option{--function-summaries}]
- [@option{-o}|@option{--object-directory} @var{directory|file}] @var{sourcefiles}
+ [@option{-q}|@option{--use-hotness-colors}]
+ [@option{-r}|@option{--relative-only}]
+ [@option{-s}|@option{--source-prefix} @var{directory}]
+ [@option{-t}|@option{--stdout}]
[@option{-u}|@option{--unconditional-branches}]
+ [@option{-x}|@option{--hash-filenames}]
+ @var{files}
@c man end
@c man begin SEEALSO
gpl(7), gfdl(7), fsf-funding(7), gcc(1) and the Info entry for @file{gcc}.
@c man begin OPTIONS
@table @gcctabopt
-@item -h
-@itemx --help
-Display help about using @command{gcov} (on the standard output), and
-exit without doing any further processing.
-
-@item -v
-@itemx --version
-Display the @command{gcov} version number (on the standard output),
-and exit without doing any further processing.
@item -a
@itemx --all-blocks
Write branch frequencies as the number of branches taken, rather than
the percentage of branches taken.
-@item -n
-@itemx --no-output
-Do not create the @command{gcov} output file.
+@item -d
+@itemx --display-progress
+Display the progress on the standard output.
+
+@item -f
+@itemx --function-summaries
+Output summaries for each function in addition to the file level summary.
+
+@item -h
+@itemx --help
+Display help about using @command{gcov} (on the standard output), and
+exit without doing any further processing.
+
+@item -i
+@itemx --json-format
+Output gcov file in an easy-to-parse JSON intermediate format
+which does not require source code for generation. The JSON
+file is compressed with gzip compression algorithm
+and the files have @file{.gcov.json.gz} extension.
+
+Structure of the JSON is following:
+
+@smallexample
+@{
+ "current_working_directory": @var{current_working_directory},
+ "data_file": @var{data_file},
+ "format_version": @var{format_version},
+ "gcc_version": @var{gcc_version}
+ "files": [@var{file}]
+@}
+@end smallexample
+
+Fields of the root element have following semantics:
+
+@itemize @bullet
+@item
+@var{current_working_directory}: working directory where
+a compilation unit was compiled
+
+@item
+@var{data_file}: name of the data file (GCDA)
+
+@item
+@var{format_version}: semantic version of the format
+
+@item
+@var{gcc_version}: version of the GCC compiler
+@end itemize
+
+Each @var{file} has the following form:
+
+@smallexample
+@{
+ "file": @var{file_name},
+ "functions": [@var{function}],
+ "lines": [@var{line}]
+@}
+@end smallexample
+
+Fields of the @var{file} element have following semantics:
+
+@itemize @bullet
+@item
+@var{file_name}: name of the source file
+@end itemize
+
+Each @var{function} has the following form:
+
+@smallexample
+@{
+ "blocks": @var{blocks},
+ "blocks_executed": @var{blocks_executed},
+ "demangled_name": "@var{demangled_name},
+ "end_column": @var{end_column},
+ "end_line": @var{end_line},
+ "execution_count": @var{execution_count},
+ "name": @var{name},
+ "start_column": @var{start_column}
+ "start_line": @var{start_line}
+@}
+@end smallexample
+
+Fields of the @var{function} element have following semantics:
+
+@itemize @bullet
+@item
+@var{blocks}: number of blocks that are in the function
+
+@item
+@var{blocks_executed}: number of executed blocks of the function
+
+@item
+@var{demangled_name}: demangled name of the function
+
+@item
+@var{end_column}: column in the source file where the function ends
+
+@item
+@var{end_line}: line in the source file where the function ends
+
+@item
+@var{execution_count}: number of executions of the function
+
+@item
+@var{name}: name of the function
+
+@item
+@var{start_column}: column in the source file where the function begins
+
+@item
+@var{start_line}: line in the source file where the function begins
+@end itemize
+
+Note that line numbers and column numbers number from 1. In the current
+implementation, @var{start_line} and @var{start_column} do not include
+any template parameters and the leading return type but that
+this is likely to be fixed in the future.
+
+Each @var{line} has the following form:
+
+@smallexample
+@{
+ "branches": [@var{branch}],
+ "count": @var{count},
+ "line_number": @var{line_number},
+ "unexecuted_block": @var{unexecuted_block}
+ "function_name": @var{function_name},
+@}
+@end smallexample
+
+Branches are present only with @var{-b} option.
+Fields of the @var{line} element have following semantics:
+
+@itemize @bullet
+@item
+@var{count}: number of executions of the line
+
+@item
+@var{line_number}: line number
+
+@item
+@var{unexecuted_block}: flag whether the line contains an unexecuted block
+(not all statements on the line are executed)
+
+@item
+@var{function_name}: a name of a function this @var{line} belongs to
+(for a line with an inlined statements can be not set)
+@end itemize
+
+Each @var{branch} has the following form:
+
+@smallexample
+@{
+ "count": @var{count},
+ "fallthrough": @var{fallthrough},
+ "throw": @var{throw}
+@}
+@end smallexample
+
+Fields of the @var{branch} element have following semantics:
+
+@itemize @bullet
+@item
+@var{count}: number of executions of the branch
+
+@item
+@var{fallthrough}: true when the branch is a fall through branch
+
+@item
+@var{throw}: true when the branch is an exceptional branch
+@end itemize
+
+@item -j
+@itemx --human-readable
+Write counts in human readable format (like 24.6k).
+
+@item -k
+@itemx --use-colors
+
+Use colors for lines of code that have zero coverage. We use red color for
+non-exceptional lines and cyan for exceptional. Same colors are used for
+basic blocks with @option{-a} option.
@item -l
@itemx --long-file-names
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
-@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}.
-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
-included file names will be complete path names.
+@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}. This can be useful if @file{x.h} is included in
+multiple source files and you want to see the individual
+contributions. If you use the @samp{-p} option, both the including
+and included file names will be complete path names.
+
+@item -m
+@itemx --demangled-names
+Display demangled function names in output. The default is to show
+mangled function names.
+
+@item -n
+@itemx --no-output
+Do not create the @command{gcov} output file.
+
+@item -o @var{directory|file}
+@itemx --object-directory @var{directory}
+@itemx --object-file @var{file}
+Specify either the directory containing the gcov data files, or the
+object path name. The @file{.gcno}, and
+@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
+input file name, without its extension. If a file is specified here,
+the data files are named after that file, without its extension.
@item -p
@itemx --preserve-paths
@file{.gcov} files. Without this option, just the filename component is
used. With this option, all directories are used, with @samp{/} characters
translated to @samp{#} characters, @file{.} directory components
-removed and @file{..}
+removed and unremoveable @file{..}
components renamed to @samp{^}. This is useful if sourcefiles are in several
-different directories. It also affects the @samp{-l} option.
+different directories.
-@item -f
-@itemx --function-summaries
-Output summaries for each function in addition to the file level summary.
+@item -q
+@itemx --use-hotness-colors
-@item -o @var{directory|file}
-@itemx --object-directory @var{directory}
-@itemx --object-file @var{file}
-Specify either the directory containing the gcov data files, or the
-object path name. The @file{.gcno}, and
-@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
-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
-option is not supplied, it defaults to the current directory.
+Emit perf-like colored output for hot lines. Legend of the color scale
+is printed at the very beginning of the output file.
+
+@item -r
+@itemx --relative-only
+Only output information about source files with a relative pathname
+(after source prefix elision). Absolute paths are usually system
+header files and coverage of any inline functions therein is normally
+uninteresting.
+
+@item -s @var{directory}
+@itemx --source-prefix @var{directory}
+A prefix for source file names to remove when generating the output
+coverage files. This option is useful when building in a separate
+directory, and the pathname to the source directory is not wanted when
+determining the output file names. Note that this prefix detection is
+applied before determining whether the source file is absolute.
+
+@item -t
+@itemx --stdout
+Output to standard output instead of output files.
@item -u
@itemx --unconditional-branches
When branch probabilities are given, include those of unconditional branches.
Unconditional branches are normally not interesting.
+@item -v
+@itemx --version
+Display the @command{gcov} version number (on the standard output),
+and exit without doing any further processing.
+
+@item -w
+@itemx --verbose
+Print verbose informations related to basic blocks and arcs.
+
+@item -x
+@itemx --hash-filenames
+When using @var{--preserve-paths},
+gcov uses the full pathname of the source files to create
+an output filename. This can lead to long filenames that can overflow
+filesystem limits. This option creates names of the form
+@file{@var{source-file}##@var{md5}.gcov},
+where the @var{source-file} component is the final filename part and
+the @var{md5} component is calculated from the full mangled name that
+would have been used otherwise. The option is an alternative
+to the @var{--preserve-paths} on systems which have a filesystem limit.
+
@end table
@command{gcov} should be run with the current directory the same as that
the source files. @command{gcov} produces files called
@file{@var{mangledname}.gcov} in the current directory. These contain
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 (or header) file
+containing code,
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
be something more complicated if the @samp{-l} or @samp{-p} options are
given. Refer to those options for details.
+If you invoke @command{gcov} with multiple input files, the
+contributions from each input file are summed. Typically you would
+invoke it with the same list of files as the final link of your executable.
+
The @file{.gcov} files contain the @samp{:} separated fields along with
program source code. The format is
Additional block information may succeed each line, when requested by
command line option. The @var{execution_count} is @samp{-} for lines
-containing no code and @samp{#####} for lines which were never executed.
-Some lines of information at the start have @var{line_number} of zero.
+containing no code. Unexecuted lines are marked @samp{#####} or
+@samp{=====}, depending on whether they are reachable by
+non-exceptional paths or only exceptional paths such as C++ exception
+handlers, respectively. Given the @samp{-a} option, unexecuted blocks are
+marked @samp{$$$$$} or @samp{%%%%%}, depending on whether a basic block
+is reachable via non-exceptional or exceptional paths.
+Executed basic blocks having a statement with zero @var{execution_count}
+end with @samp{*} character and are colored with magenta color with
+the @option{-k} option. This functionality is not supported in Ada.
+
+Note that GCC can completely remove the bodies of functions that are
+not needed -- for instance if they are inlined everywhere. Such functions
+are marked with @samp{-}, which can be confusing.
+Use the @option{-fkeep-inline-functions} and @option{-fkeep-static-functions}
+options to retain these functions and
+allow gcov to properly show their @var{execution_count}.
-The preamble lines are of the form
+Some lines of information at the start have @var{line_number} of zero.
+These preamble lines are of the form
@smallexample
-:0:@var{tag}:@var{value}
conventionally be rounded to 0% or 100% are instead printed as the
nearest non-boundary value.
-When using @command{gcov}, you must first compile your program with two
-special GCC options: @samp{-fprofile-arcs -ftest-coverage}.
+When using @command{gcov}, you must first compile your program
+with a special GCC option @samp{--coverage}.
This tells the compiler to generate additional information needed by
gcov (basically a flow graph of the program) and also includes
additional code in the object files for generating the extra profiling
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
-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.cpp}, this
is what you see when you use the basic @command{gcov} facility:
@smallexample
-$ gcc -fprofile-arcs -ftest-coverage tmp.c
+$ g++ --coverage tmp.cpp
$ a.out
-$ gcov tmp.c
-90.00% of 10 source lines executed in file tmp.c
-Creating tmp.c.gcov.
+$ gcov tmp.cpp -m
+File 'tmp.cpp'
+Lines executed:92.86% of 14
+Creating 'tmp.cpp.gcov'
@end smallexample
-The file @file{tmp.c.gcov} contains output from @command{gcov}.
+The file @file{tmp.cpp.gcov} contains output from @command{gcov}.
Here is a sample:
@smallexample
- -: 0:Source:tmp.c
+ -: 0:Source:tmp.cpp
+ -: 0:Working directory:/home/gcc/testcase
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
- -: 3:int main (void)
- 1: 4:@{
- 1: 5: int i, total;
- -: 6:
- 1: 7: total = 0;
- -: 8:
- 11: 9: for (i = 0; i < 10; i++)
- 10: 10: total += i;
- -: 11:
- 1: 12: if (total != 45)
- #####: 13: printf ("Failure\n");
- -: 14: else
- 1: 15: printf ("Success\n");
- 1: 16: return 0;
- -: 17:@}
+ -: 3:template<class T>
+ -: 4:class Foo
+ -: 5:@{
+ -: 6: public:
+ 1*: 7: Foo(): b (1000) @{@}
+------------------
+Foo<char>::Foo():
+ #####: 7: Foo(): b (1000) @{@}
+------------------
+Foo<int>::Foo():
+ 1: 7: Foo(): b (1000) @{@}
+------------------
+ 2*: 8: void inc () @{ b++; @}
+------------------
+Foo<char>::inc():
+ #####: 8: void inc () @{ b++; @}
+------------------
+Foo<int>::inc():
+ 2: 8: void inc () @{ b++; @}
+------------------
+ -: 9:
+ -: 10: private:
+ -: 11: int b;
+ -: 12:@};
+ -: 13:
+ -: 14:template class Foo<int>;
+ -: 15:template class Foo<char>;
+ -: 16:
+ -: 17:int
+ 1: 18:main (void)
+ -: 19:@{
+ -: 20: int i, total;
+ 1: 21: Foo<int> counter;
+ -: 22:
+ 1: 23: counter.inc();
+ 1: 24: counter.inc();
+ 1: 25: total = 0;
+ -: 26:
+ 11: 27: for (i = 0; i < 10; i++)
+ 10: 28: total += i;
+ -: 29:
+ 1*: 30: int v = total > 100 ? 1 : 2;
+ -: 31:
+ 1: 32: if (total != 45)
+ #####: 33: printf ("Failure\n");
+ -: 34: else
+ 1: 35: printf ("Success\n");
+ 1: 36: return 0;
+ -: 37:@}
@end smallexample
+Note that line 7 is shown in the report multiple times. First occurrence
+presents total number of execution of the line and the next two belong
+to instances of class Foo constructors. As you can also see, line 30 contains
+some unexecuted basic blocks and thus execution count has asterisk symbol.
+
When you use the @option{-a} option, you will get individual block
counts, and the output looks like this:
@smallexample
- -: 0:Source:tmp.c
+ -: 0:Source:tmp.cpp
+ -: 0:Working directory:/home/gcc/testcase
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
- -: 3:int main (void)
- 1: 4:@{
- 1: 4-block 0
- 1: 5: int i, total;
- -: 6:
- 1: 7: total = 0;
- -: 8:
- 11: 9: for (i = 0; i < 10; i++)
- 11: 9-block 0
- 10: 10: total += i;
- 10: 10-block 0
- -: 11:
- 1: 12: if (total != 45)
- 1: 12-block 0
- #####: 13: printf ("Failure\n");
- $$$$$: 13-block 0
- -: 14: else
- 1: 15: printf ("Success\n");
- 1: 15-block 0
- 1: 16: return 0;
- 1: 16-block 0
- -: 17:@}
+ -: 3:template<class T>
+ -: 4:class Foo
+ -: 5:@{
+ -: 6: public:
+ 1*: 7: Foo(): b (1000) @{@}
+------------------
+Foo<char>::Foo():
+ #####: 7: Foo(): b (1000) @{@}
+------------------
+Foo<int>::Foo():
+ 1: 7: Foo(): b (1000) @{@}
+------------------
+ 2*: 8: void inc () @{ b++; @}
+------------------
+Foo<char>::inc():
+ #####: 8: void inc () @{ b++; @}
+------------------
+Foo<int>::inc():
+ 2: 8: void inc () @{ b++; @}
+------------------
+ -: 9:
+ -: 10: private:
+ -: 11: int b;
+ -: 12:@};
+ -: 13:
+ -: 14:template class Foo<int>;
+ -: 15:template class Foo<char>;
+ -: 16:
+ -: 17:int
+ 1: 18:main (void)
+ -: 19:@{
+ -: 20: int i, total;
+ 1: 21: Foo<int> counter;
+ 1: 21-block 0
+ -: 22:
+ 1: 23: counter.inc();
+ 1: 23-block 0
+ 1: 24: counter.inc();
+ 1: 24-block 0
+ 1: 25: total = 0;
+ -: 26:
+ 11: 27: for (i = 0; i < 10; i++)
+ 1: 27-block 0
+ 11: 27-block 1
+ 10: 28: total += i;
+ 10: 28-block 0
+ -: 29:
+ 1*: 30: int v = total > 100 ? 1 : 2;
+ 1: 30-block 0
+ %%%%%: 30-block 1
+ 1: 30-block 2
+ -: 31:
+ 1: 32: if (total != 45)
+ 1: 32-block 0
+ #####: 33: printf ("Failure\n");
+ %%%%%: 33-block 0
+ -: 34: else
+ 1: 35: printf ("Success\n");
+ 1: 35-block 0
+ 1: 36: return 0;
+ 1: 36-block 0
+ -: 37:@}
@end smallexample
In this mode, each basic block is only shown on one line -- the last
Because of the way GCC instruments calls, a call count can be shown
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 33 contains a basic block that was not executed.
@need 450
When you use the @option{-b} option, your output looks like this:
@smallexample
-$ gcov -b 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 taken at least once in file tmp.c
-50.00% of 2 calls executed in file tmp.c
-Creating tmp.c.gcov.
-@end smallexample
-
-Here is a sample of a resulting @file{tmp.c.gcov} file:
-
-@smallexample
- -: 0:Source:tmp.c
+ -: 0:Source:tmp.cpp
+ -: 0:Working directory:/home/gcc/testcase
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
- -: 3:int main (void)
-function main called 1 returned 1 blocks executed 75%
- 1: 4:@{
- 1: 5: int i, total;
- -: 6:
- 1: 7: total = 0;
- -: 8:
- 11: 9: for (i = 0; i < 10; i++)
+ -: 3:template<class T>
+ -: 4:class Foo
+ -: 5:@{
+ -: 6: public:
+ 1*: 7: Foo(): b (1000) @{@}
+------------------
+Foo<char>::Foo():
+function Foo<char>::Foo() called 0 returned 0% blocks executed 0%
+ #####: 7: Foo(): b (1000) @{@}
+------------------
+Foo<int>::Foo():
+function Foo<int>::Foo() called 1 returned 100% blocks executed 100%
+ 1: 7: Foo(): b (1000) @{@}
+------------------
+ 2*: 8: void inc () @{ b++; @}
+------------------
+Foo<char>::inc():
+function Foo<char>::inc() called 0 returned 0% blocks executed 0%
+ #####: 8: void inc () @{ b++; @}
+------------------
+Foo<int>::inc():
+function Foo<int>::inc() called 2 returned 100% blocks executed 100%
+ 2: 8: void inc () @{ b++; @}
+------------------
+ -: 9:
+ -: 10: private:
+ -: 11: int b;
+ -: 12:@};
+ -: 13:
+ -: 14:template class Foo<int>;
+ -: 15:template class Foo<char>;
+ -: 16:
+ -: 17:int
+function main called 1 returned 100% blocks executed 81%
+ 1: 18:main (void)
+ -: 19:@{
+ -: 20: int i, total;
+ 1: 21: Foo<int> counter;
+call 0 returned 100%
+branch 1 taken 100% (fallthrough)
+branch 2 taken 0% (throw)
+ -: 22:
+ 1: 23: counter.inc();
+call 0 returned 100%
+branch 1 taken 100% (fallthrough)
+branch 2 taken 0% (throw)
+ 1: 24: counter.inc();
+call 0 returned 100%
+branch 1 taken 100% (fallthrough)
+branch 2 taken 0% (throw)
+ 1: 25: total = 0;
+ -: 26:
+ 11: 27: for (i = 0; i < 10; i++)
branch 0 taken 91% (fallthrough)
branch 1 taken 9%
- 10: 10: total += i;
- -: 11:
- 1: 12: if (total != 45)
+ 10: 28: total += i;
+ -: 29:
+ 1*: 30: int v = total > 100 ? 1 : 2;
branch 0 taken 0% (fallthrough)
branch 1 taken 100%
- #####: 13: printf ("Failure\n");
+ -: 31:
+ 1: 32: if (total != 45)
+branch 0 taken 0% (fallthrough)
+branch 1 taken 100%
+ #####: 33: printf ("Failure\n");
call 0 never executed
- -: 14: else
- 1: 15: printf ("Success\n");
-call 0 called 1 returned 100%
- 1: 16: return 0;
- -: 17:@}
+branch 1 never executed
+branch 2 never executed
+ -: 34: else
+ 1: 35: printf ("Success\n");
+call 0 returned 100%
+branch 1 taken 100% (fallthrough)
+branch 2 taken 0% (throw)
+ 1: 36: return 0;
+ -: 37:@}
@end smallexample
For each function, a line is printed showing how many times the function
@section Using @command{gcov} with GCC Optimization
If you plan to use @command{gcov} to help optimize your code, you must
-first compile your program with two special GCC options:
-@samp{-fprofile-arcs -ftest-coverage}. Aside from that, you can use any
+first compile your program with a special GCC option
+@samp{--coverage}. Aside from that, you can use any
other GCC options; but if you want to prove that every single line
in your program was executed, you should not compile with optimization
at the same time. On some machines the optimizer can eliminate some
coverage of all the uses of the inline function will be shown for the
same source lines, the line counts themselves might seem inconsistent.
+Long-running applications can use the @code{__gcov_reset} and @code{__gcov_dump}
+facilities to restrict profile collection to the program region of
+interest. Calling @code{__gcov_reset(void)} will clear all profile counters
+to zero, and calling @code{__gcov_dump(void)} will cause the profile information
+collected at that point to be dumped to @file{.gcda} output files.
+Instrumented applications use a static destructor with priority 99
+to invoke the @code{__gcov_dump} function. Thus @code{__gcov_dump}
+is executed after all user defined static destructors,
+as well as handlers registered with @code{atexit}.
+If an executable loads a dynamic shared object via dlopen functionality,
+@option{-Wl,--dynamic-list-data} is needed to dump all profile data.
+
+Profiling run-time library reports various errors related to profile
+manipulation and profile saving. Errors are printed into standard error output
+or @samp{GCOV_ERROR_FILE} file, if environment variable is used.
+In order to terminate immediately after an errors occurs
+set @samp{GCOV_EXIT_AT_ERROR} environment variable.
+That can help users to find profile clashing which leads
+to a misleading profile.
+
@c man end
@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
are derived from the original @emph{object} file by substituting the
-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
-stored in a platform-independent format.
-
-The @file{.gcno} file is generated when the source file is compiled with
-the GCC @option{-ftest-coverage} option. It contains information to
+file suffix with either @file{.gcno}, or @file{.gcda}. The files
+contain coverage and profile data stored in a platform-independent format.
+The @file{.gcno} files are placed in the same directory as the object
+file. By default, the @file{.gcda} files are also stored in the same
+directory as the object file, but the GCC @option{-fprofile-dir} option
+may be used to store the @file{.gcda} files in a separate directory.
+
+The @file{.gcno} notes file is generated when the source file is compiled
+with the GCC @option{-ftest-coverage} option. It contains information to
reconstruct the basic block graphs and assign source line numbers to
blocks.
-The @file{.gcda} file is generated when a program containing object files
-built with the GCC @option{-fprofile-arcs} option is executed. A
-separate @file{.gcda} file is created for each object file compiled with
-this option. It contains arc transition counts, and some summary
-information.
+The @file{.gcda} count data file is generated when a program containing
+object files built with the GCC @option{-fprofile-arcs} option is executed.
+A separate @file{.gcda} file is created for each object file compiled with
+this option. It contains arc transition counts, value profile counts, and
+some summary information.
-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
-coverage files.
+It is not recommended to access the coverage files directly.
+Consumers should use the intermediate format that is provided
+by @command{gcov} tool via @option{--json-format} option.
@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
-source file compiled with @option{-fprofile-arcs}, an accompanying @file{.gcda}
-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 will cause profile output to be generated. For each
+source file compiled with @option{-fprofile-arcs}, an accompanying @file{.gcda}
+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.
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
@item
-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.
+GCOV_PREFIX contains the prefix to add to the absolute paths
+in the object file. Prefix can be absolute, or relative. The
+default is no prefix.
@item
GCOV_PREFIX_STRIP indicates the how many initial directory names to strip off
the hardwired absolute paths. Default value is 0.
-@emph{Note:} GCOV_PREFIX_STRIP has no effect if GCOV_PREFIX is undefined, empty
-or non-absolute.
+@emph{Note:} If GCOV_PREFIX_STRIP is set without GCOV_PREFIX is undefined,
+ then a relative path is made out of the hardwired absolute paths.
@end itemize
For example, if the object file @file{/user/build/foo.o} was built with
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
-use them for profile directed optimizations (@option{--use-profile}), or to
+use them for profile directed optimizations (@option{-fprofile-use}), or to
use the @command{gcov} tool.
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