1035 lines
38 KiB
Groff
1035 lines
38 KiB
Groff
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.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
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.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
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\{\
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.\" ========================================================================
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.\"
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|
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.IX Title "GCOV 1"
|
||
|
|
.TH GCOV 1 "2019-10-25" "gcc-9.2.1" "GNU"
|
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|
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.\" For nroff, turn off justification. Always turn off hyphenation; it makes
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.\" way too many mistakes in technical documents.
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.if n .ad l
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.nh
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.SH "NAME"
|
||
|
|
gcov \- coverage testing tool
|
||
|
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.SH "SYNOPSIS"
|
||
|
|
.IX Header "SYNOPSIS"
|
||
|
|
gcov [\fB\-v\fR|\fB\-\-version\fR] [\fB\-h\fR|\fB\-\-help\fR]
|
||
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[\fB\-a\fR|\fB\-\-all\-blocks\fR]
|
||
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[\fB\-b\fR|\fB\-\-branch\-probabilities\fR]
|
||
|
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[\fB\-c\fR|\fB\-\-branch\-counts\fR]
|
||
|
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[\fB\-d\fR|\fB\-\-display\-progress\fR]
|
||
|
|
[\fB\-f\fR|\fB\-\-function\-summaries\fR]
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||
|
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[\fB\-i\fR|\fB\-\-json\-format\fR]
|
||
|
|
[\fB\-j\fR|\fB\-\-human\-readable\fR]
|
||
|
|
[\fB\-k\fR|\fB\-\-use\-colors\fR]
|
||
|
|
[\fB\-l\fR|\fB\-\-long\-file\-names\fR]
|
||
|
|
[\fB\-m\fR|\fB\-\-demangled\-names\fR]
|
||
|
|
[\fB\-n\fR|\fB\-\-no\-output\fR]
|
||
|
|
[\fB\-o\fR|\fB\-\-object\-directory\fR \fIdirectory|file\fR]
|
||
|
|
[\fB\-p\fR|\fB\-\-preserve\-paths\fR]
|
||
|
|
[\fB\-q\fR|\fB\-\-use\-hotness\-colors\fR]
|
||
|
|
[\fB\-r\fR|\fB\-\-relative\-only\fR]
|
||
|
|
[\fB\-s\fR|\fB\-\-source\-prefix\fR \fIdirectory\fR]
|
||
|
|
[\fB\-t\fR|\fB\-\-stdout\fR]
|
||
|
|
[\fB\-u\fR|\fB\-\-unconditional\-branches\fR]
|
||
|
|
[\fB\-x\fR|\fB\-\-hash\-filenames\fR]
|
||
|
|
\fIfiles\fR
|
||
|
|
.SH "DESCRIPTION"
|
||
|
|
.IX Header "DESCRIPTION"
|
||
|
|
\&\fBgcov\fR is a test coverage program. Use it in concert with \s-1GCC\s0
|
||
|
|
to analyze your programs to help create more efficient, faster running
|
||
|
|
code and to discover untested parts of your program. You can use
|
||
|
|
\&\fBgcov\fR as a profiling tool to help discover where your
|
||
|
|
optimization efforts will best affect your code. You can also use
|
||
|
|
\&\fBgcov\fR along with the other profiling tool, \fBgprof\fR, to
|
||
|
|
assess which parts of your code use the greatest amount of computing
|
||
|
|
time.
|
||
|
|
.PP
|
||
|
|
Profiling tools help you analyze your code's performance. Using a
|
||
|
|
profiler such as \fBgcov\fR or \fBgprof\fR, you can find out some
|
||
|
|
basic performance statistics, such as:
|
||
|
|
.IP "*" 4
|
||
|
|
how often each line of code executes
|
||
|
|
.IP "*" 4
|
||
|
|
what lines of code are actually executed
|
||
|
|
.IP "*" 4
|
||
|
|
how much computing time each section of code uses
|
||
|
|
.PP
|
||
|
|
Once you know these things about how your code works when compiled, you
|
||
|
|
can look at each module to see which modules should be optimized.
|
||
|
|
\&\fBgcov\fR helps you determine where to work on optimization.
|
||
|
|
.PP
|
||
|
|
Software developers also use coverage testing in concert with
|
||
|
|
testsuites, to make sure software is actually good enough for a release.
|
||
|
|
Testsuites can verify that a program works as expected; a coverage
|
||
|
|
program tests to see how much of the program is exercised by the
|
||
|
|
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
|
||
|
|
final product.
|
||
|
|
.PP
|
||
|
|
You should compile your code without optimization if you plan to use
|
||
|
|
\&\fBgcov\fR because the optimization, by combining some lines of code
|
||
|
|
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
|
||
|
|
time. Likewise, because \fBgcov\fR accumulates statistics by line (at
|
||
|
|
the lowest resolution), it works best with a programming style that
|
||
|
|
places only one statement on each line. If you use complicated macros
|
||
|
|
that expand to loops or to other control structures, the statistics are
|
||
|
|
less helpful\-\-\-they only report on the line where the macro call
|
||
|
|
appears. If your complex macros behave like functions, you can replace
|
||
|
|
them with inline functions to solve this problem.
|
||
|
|
.PP
|
||
|
|
\&\fBgcov\fR creates a logfile called \fI\fIsourcefile\fI.gcov\fR which
|
||
|
|
indicates how many times each line of a source file \fI\fIsourcefile\fI.c\fR
|
||
|
|
has executed. You can use these logfiles along with \fBgprof\fR to aid
|
||
|
|
in fine-tuning the performance of your programs. \fBgprof\fR gives
|
||
|
|
timing information you can use along with the information you get from
|
||
|
|
\&\fBgcov\fR.
|
||
|
|
.PP
|
||
|
|
\&\fBgcov\fR works only on code compiled with \s-1GCC\s0. It is not
|
||
|
|
compatible with any other profiling or test coverage mechanism.
|
||
|
|
.SH "OPTIONS"
|
||
|
|
.IX Header "OPTIONS"
|
||
|
|
.IP "\fB\-a\fR" 4
|
||
|
|
.IX Item "-a"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-all\-blocks\fR" 4
|
||
|
|
.IX Item "--all-blocks"
|
||
|
|
.PD
|
||
|
|
Write individual execution counts for every basic block. Normally gcov
|
||
|
|
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
|
||
|
|
executed.
|
||
|
|
.IP "\fB\-b\fR" 4
|
||
|
|
.IX Item "-b"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-branch\-probabilities\fR" 4
|
||
|
|
.IX Item "--branch-probabilities"
|
||
|
|
.PD
|
||
|
|
Write branch frequencies to the output file, and write branch summary
|
||
|
|
info to the standard output. This option allows you to see how often
|
||
|
|
each branch in your program was taken. Unconditional branches will not
|
||
|
|
be shown, unless the \fB\-u\fR option is given.
|
||
|
|
.IP "\fB\-c\fR" 4
|
||
|
|
.IX Item "-c"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-branch\-counts\fR" 4
|
||
|
|
.IX Item "--branch-counts"
|
||
|
|
.PD
|
||
|
|
Write branch frequencies as the number of branches taken, rather than
|
||
|
|
the percentage of branches taken.
|
||
|
|
.IP "\fB\-d\fR" 4
|
||
|
|
.IX Item "-d"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-display\-progress\fR" 4
|
||
|
|
.IX Item "--display-progress"
|
||
|
|
.PD
|
||
|
|
Display the progress on the standard output.
|
||
|
|
.IP "\fB\-f\fR" 4
|
||
|
|
.IX Item "-f"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-function\-summaries\fR" 4
|
||
|
|
.IX Item "--function-summaries"
|
||
|
|
.PD
|
||
|
|
Output summaries for each function in addition to the file level summary.
|
||
|
|
.IP "\fB\-h\fR" 4
|
||
|
|
.IX Item "-h"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-help\fR" 4
|
||
|
|
.IX Item "--help"
|
||
|
|
.PD
|
||
|
|
Display help about using \fBgcov\fR (on the standard output), and
|
||
|
|
exit without doing any further processing.
|
||
|
|
.IP "\fB\-i\fR" 4
|
||
|
|
.IX Item "-i"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-json\-format\fR" 4
|
||
|
|
.IX Item "--json-format"
|
||
|
|
.PD
|
||
|
|
Output gcov file in an easy-to-parse \s-1JSON\s0 intermediate format
|
||
|
|
which does not require source code for generation. The \s-1JSON\s0
|
||
|
|
file is compressed with gzip compression algorithm
|
||
|
|
and the files have \fI.gcov.json.gz\fR extension.
|
||
|
|
.Sp
|
||
|
|
Structure of the \s-1JSON\s0 is following:
|
||
|
|
.Sp
|
||
|
|
.Vb 7
|
||
|
|
\& {
|
||
|
|
\& "current_working_directory": <current_working_directory>,
|
||
|
|
\& "data_file": <data_file>,
|
||
|
|
\& "format_version": <format_version>,
|
||
|
|
\& "gcc_version": <gcc_version>
|
||
|
|
\& "files": [<file>]
|
||
|
|
\& }
|
||
|
|
.Ve
|
||
|
|
.Sp
|
||
|
|
Fields of the root element have following semantics:
|
||
|
|
.RS 4
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIcurrent_working_directory\fR: working directory where
|
||
|
|
a compilation unit was compiled
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIdata_file\fR: name of the data file (\s-1GCDA\s0)
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIformat_version\fR: semantic version of the format
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIgcc_version\fR: version of the \s-1GCC\s0 compiler
|
||
|
|
.RE
|
||
|
|
.RS 4
|
||
|
|
.Sp
|
||
|
|
Each \fIfile\fR has the following form:
|
||
|
|
.Sp
|
||
|
|
.Vb 5
|
||
|
|
\& {
|
||
|
|
\& "file": <file_name>,
|
||
|
|
\& "functions": [<function>],
|
||
|
|
\& "lines": [<line>]
|
||
|
|
\& }
|
||
|
|
.Ve
|
||
|
|
.Sp
|
||
|
|
Fields of the \fIfile\fR element have following semantics:
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIfile_name\fR: name of the source file
|
||
|
|
.RE
|
||
|
|
.RS 4
|
||
|
|
.Sp
|
||
|
|
Each \fIfunction\fR has the following form:
|
||
|
|
.Sp
|
||
|
|
.Vb 11
|
||
|
|
\& {
|
||
|
|
\& "blocks": <blocks>,
|
||
|
|
\& "blocks_executed": <blocks_executed>,
|
||
|
|
\& "demangled_name": "<demangled_name>,
|
||
|
|
\& "end_column": <end_column>,
|
||
|
|
\& "end_line": <end_line>,
|
||
|
|
\& "execution_count": <execution_count>,
|
||
|
|
\& "name": <name>,
|
||
|
|
\& "start_column": <start_column>
|
||
|
|
\& "start_line": <start_line>
|
||
|
|
\& }
|
||
|
|
.Ve
|
||
|
|
.Sp
|
||
|
|
Fields of the \fIfunction\fR element have following semantics:
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIblocks\fR: number of blocks that are in the function
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIblocks_executed\fR: number of executed blocks of the function
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIdemangled_name\fR: demangled name of the function
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIend_column\fR: column in the source file where the function ends
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIend_line\fR: line in the source file where the function ends
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIexecution_count\fR: number of executions of the function
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIname\fR: name of the function
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIstart_column\fR: column in the source file where the function begins
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIstart_line\fR: line in the source file where the function begins
|
||
|
|
.RE
|
||
|
|
.RS 4
|
||
|
|
.Sp
|
||
|
|
Note that line numbers and column numbers number from 1. In the current
|
||
|
|
implementation, \fIstart_line\fR and \fIstart_column\fR do not include
|
||
|
|
any template parameters and the leading return type but that
|
||
|
|
this is likely to be fixed in the future.
|
||
|
|
.Sp
|
||
|
|
Each \fIline\fR has the following form:
|
||
|
|
.Sp
|
||
|
|
.Vb 7
|
||
|
|
\& {
|
||
|
|
\& "branches": [<branch>],
|
||
|
|
\& "count": <count>,
|
||
|
|
\& "line_number": <line_number>,
|
||
|
|
\& "unexecuted_block": <unexecuted_block>
|
||
|
|
\& "function_name": <function_name>,
|
||
|
|
\& }
|
||
|
|
.Ve
|
||
|
|
.Sp
|
||
|
|
Branches are present only with \fI\-b\fR option.
|
||
|
|
Fields of the \fIline\fR element have following semantics:
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIcount\fR: number of executions of the line
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIline_number\fR: line number
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIunexecuted_block\fR: flag whether the line contains an unexecuted block
|
||
|
|
(not all statements on the line are executed)
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIfunction_name\fR: a name of a function this \fIline\fR belongs to
|
||
|
|
(for a line with an inlined statements can be not set)
|
||
|
|
.RE
|
||
|
|
.RS 4
|
||
|
|
.Sp
|
||
|
|
Each \fIbranch\fR has the following form:
|
||
|
|
.Sp
|
||
|
|
.Vb 5
|
||
|
|
\& {
|
||
|
|
\& "count": <count>,
|
||
|
|
\& "fallthrough": <fallthrough>,
|
||
|
|
\& "throw": <throw>
|
||
|
|
\& }
|
||
|
|
.Ve
|
||
|
|
.Sp
|
||
|
|
Fields of the \fIbranch\fR element have following semantics:
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIcount\fR: number of executions of the branch
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIfallthrough\fR: true when the branch is a fall through branch
|
||
|
|
.IP "*" 4
|
||
|
|
\&\fIthrow\fR: true when the branch is an exceptional branch
|
||
|
|
.RE
|
||
|
|
.RS 4
|
||
|
|
.RE
|
||
|
|
.IP "\fB\-j\fR" 4
|
||
|
|
.IX Item "-j"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-human\-readable\fR" 4
|
||
|
|
.IX Item "--human-readable"
|
||
|
|
.PD
|
||
|
|
Write counts in human readable format (like 24.6k).
|
||
|
|
.IP "\fB\-k\fR" 4
|
||
|
|
.IX Item "-k"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-use\-colors\fR" 4
|
||
|
|
.IX Item "--use-colors"
|
||
|
|
.PD
|
||
|
|
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 \fB\-a\fR option.
|
||
|
|
.IP "\fB\-l\fR" 4
|
||
|
|
.IX Item "-l"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-long\-file\-names\fR" 4
|
||
|
|
.IX Item "--long-file-names"
|
||
|
|
.PD
|
||
|
|
Create long file names for included source files. For example, if the
|
||
|
|
header file \fIx.h\fR contains code, and was included in the file
|
||
|
|
\&\fIa.c\fR, then running \fBgcov\fR on the file \fIa.c\fR will
|
||
|
|
produce an output file called \fIa.c##x.h.gcov\fR instead of
|
||
|
|
\&\fIx.h.gcov\fR. This can be useful if \fIx.h\fR is included in
|
||
|
|
multiple source files and you want to see the individual
|
||
|
|
contributions. If you use the \fB\-p\fR option, both the including
|
||
|
|
and included file names will be complete path names.
|
||
|
|
.IP "\fB\-m\fR" 4
|
||
|
|
.IX Item "-m"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-demangled\-names\fR" 4
|
||
|
|
.IX Item "--demangled-names"
|
||
|
|
.PD
|
||
|
|
Display demangled function names in output. The default is to show
|
||
|
|
mangled function names.
|
||
|
|
.IP "\fB\-n\fR" 4
|
||
|
|
.IX Item "-n"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-no\-output\fR" 4
|
||
|
|
.IX Item "--no-output"
|
||
|
|
.PD
|
||
|
|
Do not create the \fBgcov\fR output file.
|
||
|
|
.IP "\fB\-o\fR \fIdirectory|file\fR" 4
|
||
|
|
.IX Item "-o directory|file"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-object\-directory\fR \fIdirectory\fR" 4
|
||
|
|
.IX Item "--object-directory directory"
|
||
|
|
.IP "\fB\-\-object\-file\fR \fIfile\fR" 4
|
||
|
|
.IX Item "--object-file file"
|
||
|
|
.PD
|
||
|
|
Specify either the directory containing the gcov data files, or the
|
||
|
|
object path name. The \fI.gcno\fR, and
|
||
|
|
\&\fI.gcda\fR 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.
|
||
|
|
.IP "\fB\-p\fR" 4
|
||
|
|
.IX Item "-p"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-preserve\-paths\fR" 4
|
||
|
|
.IX Item "--preserve-paths"
|
||
|
|
.PD
|
||
|
|
Preserve complete path information in the names of generated
|
||
|
|
\&\fI.gcov\fR files. Without this option, just the filename component is
|
||
|
|
used. With this option, all directories are used, with \fB/\fR characters
|
||
|
|
translated to \fB#\fR characters, \fI.\fR directory components
|
||
|
|
removed and unremoveable \fI..\fR
|
||
|
|
components renamed to \fB^\fR. This is useful if sourcefiles are in several
|
||
|
|
different directories.
|
||
|
|
.IP "\fB\-q\fR" 4
|
||
|
|
.IX Item "-q"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-use\-hotness\-colors\fR" 4
|
||
|
|
.IX Item "--use-hotness-colors"
|
||
|
|
.PD
|
||
|
|
Emit perf-like colored output for hot lines. Legend of the color scale
|
||
|
|
is printed at the very beginning of the output file.
|
||
|
|
.IP "\fB\-r\fR" 4
|
||
|
|
.IX Item "-r"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-relative\-only\fR" 4
|
||
|
|
.IX Item "--relative-only"
|
||
|
|
.PD
|
||
|
|
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.
|
||
|
|
.IP "\fB\-s\fR \fIdirectory\fR" 4
|
||
|
|
.IX Item "-s directory"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-source\-prefix\fR \fIdirectory\fR" 4
|
||
|
|
.IX Item "--source-prefix directory"
|
||
|
|
.PD
|
||
|
|
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.
|
||
|
|
.IP "\fB\-t\fR" 4
|
||
|
|
.IX Item "-t"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-stdout\fR" 4
|
||
|
|
.IX Item "--stdout"
|
||
|
|
.PD
|
||
|
|
Output to standard output instead of output files.
|
||
|
|
.IP "\fB\-u\fR" 4
|
||
|
|
.IX Item "-u"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-unconditional\-branches\fR" 4
|
||
|
|
.IX Item "--unconditional-branches"
|
||
|
|
.PD
|
||
|
|
When branch probabilities are given, include those of unconditional branches.
|
||
|
|
Unconditional branches are normally not interesting.
|
||
|
|
.IP "\fB\-v\fR" 4
|
||
|
|
.IX Item "-v"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-version\fR" 4
|
||
|
|
.IX Item "--version"
|
||
|
|
.PD
|
||
|
|
Display the \fBgcov\fR version number (on the standard output),
|
||
|
|
and exit without doing any further processing.
|
||
|
|
.IP "\fB\-w\fR" 4
|
||
|
|
.IX Item "-w"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-verbose\fR" 4
|
||
|
|
.IX Item "--verbose"
|
||
|
|
.PD
|
||
|
|
Print verbose informations related to basic blocks and arcs.
|
||
|
|
.IP "\fB\-x\fR" 4
|
||
|
|
.IX Item "-x"
|
||
|
|
.PD 0
|
||
|
|
.IP "\fB\-\-hash\-filenames\fR" 4
|
||
|
|
.IX Item "--hash-filenames"
|
||
|
|
.PD
|
||
|
|
When using \fI\-\-preserve\-paths\fR,
|
||
|
|
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
|
||
|
|
\&\fI\fIsource-file\fI##\fImd5\fI.gcov\fR,
|
||
|
|
where the \fIsource-file\fR component is the final filename part and
|
||
|
|
the \fImd5\fR component is calculated from the full mangled name that
|
||
|
|
would have been used otherwise. The option is an alternative
|
||
|
|
to the \fI\-\-preserve\-paths\fR on systems which have a filesystem limit.
|
||
|
|
.PP
|
||
|
|
\&\fBgcov\fR should be run with the current directory the same as that
|
||
|
|
when you invoked the compiler. Otherwise it will not be able to locate
|
||
|
|
the source files. \fBgcov\fR produces files called
|
||
|
|
\&\fI\fImangledname\fI.gcov\fR in the current directory. These contain
|
||
|
|
the coverage information of the source file they correspond to.
|
||
|
|
One \fI.gcov\fR file is produced for each source (or header) file
|
||
|
|
containing code,
|
||
|
|
which was compiled to produce the data files. The \fImangledname\fR part
|
||
|
|
of the output file name is usually simply the source file name, but can
|
||
|
|
be something more complicated if the \fB\-l\fR or \fB\-p\fR options are
|
||
|
|
given. Refer to those options for details.
|
||
|
|
.PP
|
||
|
|
If you invoke \fBgcov\fR 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.
|
||
|
|
.PP
|
||
|
|
The \fI.gcov\fR files contain the \fB:\fR separated fields along with
|
||
|
|
program source code. The format is
|
||
|
|
.PP
|
||
|
|
.Vb 1
|
||
|
|
\& <execution_count>:<line_number>:<source line text>
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
Additional block information may succeed each line, when requested by
|
||
|
|
command line option. The \fIexecution_count\fR is \fB\-\fR for lines
|
||
|
|
containing no code. Unexecuted lines are marked \fB#####\fR or
|
||
|
|
\&\fB=====\fR, depending on whether they are reachable by
|
||
|
|
non-exceptional paths or only exceptional paths such as \*(C+ exception
|
||
|
|
handlers, respectively. Given the \fB\-a\fR option, unexecuted blocks are
|
||
|
|
marked \fB$$$$$\fR or \fB%%%%%\fR, depending on whether a basic block
|
||
|
|
is reachable via non-exceptional or exceptional paths.
|
||
|
|
Executed basic blocks having a statement with zero \fIexecution_count\fR
|
||
|
|
end with \fB*\fR character and are colored with magenta color with
|
||
|
|
the \fB\-k\fR option. This functionality is not supported in Ada.
|
||
|
|
.PP
|
||
|
|
Note that \s-1GCC\s0 can completely remove the bodies of functions that are
|
||
|
|
not needed \*(-- for instance if they are inlined everywhere. Such functions
|
||
|
|
are marked with \fB\-\fR, which can be confusing.
|
||
|
|
Use the \fB\-fkeep\-inline\-functions\fR and \fB\-fkeep\-static\-functions\fR
|
||
|
|
options to retain these functions and
|
||
|
|
allow gcov to properly show their \fIexecution_count\fR.
|
||
|
|
.PP
|
||
|
|
Some lines of information at the start have \fIline_number\fR of zero.
|
||
|
|
These preamble lines are of the form
|
||
|
|
.PP
|
||
|
|
.Vb 1
|
||
|
|
\& \-:0:<tag>:<value>
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
The ordering and number of these preamble lines will be augmented as
|
||
|
|
\&\fBgcov\fR development progresses \-\-\- do not rely on them remaining
|
||
|
|
unchanged. Use \fItag\fR to locate a particular preamble line.
|
||
|
|
.PP
|
||
|
|
The additional block information is of the form
|
||
|
|
.PP
|
||
|
|
.Vb 1
|
||
|
|
\& <tag> <information>
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
The \fIinformation\fR is human readable, but designed to be simple
|
||
|
|
enough for machine parsing too.
|
||
|
|
.PP
|
||
|
|
When printing percentages, 0% and 100% are only printed when the values
|
||
|
|
are \fIexactly\fR 0% and 100% respectively. Other values which would
|
||
|
|
conventionally be rounded to 0% or 100% are instead printed as the
|
||
|
|
nearest non-boundary value.
|
||
|
|
.PP
|
||
|
|
When using \fBgcov\fR, you must first compile your program
|
||
|
|
with a special \s-1GCC\s0 option \fB\-\-coverage\fR.
|
||
|
|
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
|
||
|
|
information needed by gcov. These additional files are placed in the
|
||
|
|
directory where the object file is located.
|
||
|
|
.PP
|
||
|
|
Running the program will cause profile output to be generated. For each
|
||
|
|
source file compiled with \fB\-fprofile\-arcs\fR, an accompanying
|
||
|
|
\&\fI.gcda\fR file will be placed in the object file directory.
|
||
|
|
.PP
|
||
|
|
Running \fBgcov\fR 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 \fItmp.cpp\fR, this
|
||
|
|
is what you see when you use the basic \fBgcov\fR facility:
|
||
|
|
.PP
|
||
|
|
.Vb 6
|
||
|
|
\& $ g++ \-\-coverage tmp.cpp
|
||
|
|
\& $ a.out
|
||
|
|
\& $ gcov tmp.cpp \-m
|
||
|
|
\& File \*(Aqtmp.cpp\*(Aq
|
||
|
|
\& Lines executed:92.86% of 14
|
||
|
|
\& Creating \*(Aqtmp.cpp.gcov\*(Aq
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
The file \fItmp.cpp.gcov\fR contains output from \fBgcov\fR.
|
||
|
|
Here is a sample:
|
||
|
|
.PP
|
||
|
|
.Vb 10
|
||
|
|
\& \-: 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: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\en");
|
||
|
|
\& \-: 34: else
|
||
|
|
\& 1: 35: printf ("Success\en");
|
||
|
|
\& 1: 36: return 0;
|
||
|
|
\& \-: 37:}
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
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.
|
||
|
|
.PP
|
||
|
|
When you use the \fB\-a\fR option, you will get individual block
|
||
|
|
counts, and the output looks like this:
|
||
|
|
.PP
|
||
|
|
.Vb 10
|
||
|
|
\& \-: 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: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\en");
|
||
|
|
\& %%%%%: 33\-block 0
|
||
|
|
\& \-: 34: else
|
||
|
|
\& 1: 35: printf ("Success\en");
|
||
|
|
\& 1: 35\-block 0
|
||
|
|
\& 1: 36: return 0;
|
||
|
|
\& 1: 36\-block 0
|
||
|
|
\& \-: 37:}
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
execution count of that last line, and other lines will not be shown
|
||
|
|
to contain code, unless previous blocks end on those lines.
|
||
|
|
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
|
||
|
|
block, the branch and call counts of the block will be shown, if the
|
||
|
|
\&\fB\-b\fR option is given.
|
||
|
|
.PP
|
||
|
|
Because of the way \s-1GCC\s0 instruments calls, a call count can be shown
|
||
|
|
after a line with no individual blocks.
|
||
|
|
As you can see, line 33 contains a basic block that was not executed.
|
||
|
|
.PP
|
||
|
|
When you use the \fB\-b\fR option, your output looks like this:
|
||
|
|
.PP
|
||
|
|
.Vb 10
|
||
|
|
\& \-: 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: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: 28: total += i;
|
||
|
|
\& \-: 29:
|
||
|
|
\& 1*: 30: int v = total > 100 ? 1 : 2;
|
||
|
|
\& branch 0 taken 0% (fallthrough)
|
||
|
|
\& branch 1 taken 100%
|
||
|
|
\& \-: 31:
|
||
|
|
\& 1: 32: if (total != 45)
|
||
|
|
\& branch 0 taken 0% (fallthrough)
|
||
|
|
\& branch 1 taken 100%
|
||
|
|
\& #####: 33: printf ("Failure\en");
|
||
|
|
\& call 0 never executed
|
||
|
|
\& branch 1 never executed
|
||
|
|
\& branch 2 never executed
|
||
|
|
\& \-: 34: else
|
||
|
|
\& 1: 35: printf ("Success\en");
|
||
|
|
\& call 0 returned 100%
|
||
|
|
\& branch 1 taken 100% (fallthrough)
|
||
|
|
\& branch 2 taken 0% (throw)
|
||
|
|
\& 1: 36: return 0;
|
||
|
|
\& \-: 37:}
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
function's blocks were executed.
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
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
|
||
|
|
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,
|
||
|
|
the lowest numbered branch or call will correspond to the leftmost construct
|
||
|
|
on the source line.
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
number of times the branch was executed will be printed. Otherwise, the
|
||
|
|
message \*(L"never executed\*(R" is printed.
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
of times the call was executed will be printed. This will usually be
|
||
|
|
100%, but may be less for functions that call \f(CW\*(C`exit\*(C'\fR or \f(CW\*(C`longjmp\*(C'\fR,
|
||
|
|
and thus may not return every time they are called.
|
||
|
|
.PP
|
||
|
|
The execution counts are cumulative. If the example program were
|
||
|
|
executed again without removing the \fI.gcda\fR file, the count for the
|
||
|
|
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
|
||
|
|
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
|
||
|
|
provide more accurate long-term information over a large number of
|
||
|
|
program runs.
|
||
|
|
.PP
|
||
|
|
The data in the \fI.gcda\fR files is saved immediately before the program
|
||
|
|
exits. For each source file compiled with \fB\-fprofile\-arcs\fR, the
|
||
|
|
profiling code first attempts to read in an existing \fI.gcda\fR file; if
|
||
|
|
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
|
||
|
|
new execution counts and finally writes the data to the file.
|
||
|
|
.SS "Using \fBgcov\fP with \s-1GCC\s0 Optimization"
|
||
|
|
.IX Subsection "Using gcov with GCC Optimization"
|
||
|
|
If you plan to use \fBgcov\fR to help optimize your code, you must
|
||
|
|
first compile your program with a special \s-1GCC\s0 option
|
||
|
|
\&\fB\-\-coverage\fR. Aside from that, you can use any
|
||
|
|
other \s-1GCC\s0 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
|
||
|
|
simple code lines by combining them with other lines. For example, code
|
||
|
|
like this:
|
||
|
|
.PP
|
||
|
|
.Vb 4
|
||
|
|
\& if (a != b)
|
||
|
|
\& c = 1;
|
||
|
|
\& else
|
||
|
|
\& c = 0;
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
can be compiled into one instruction on some machines. In this case,
|
||
|
|
there is no way for \fBgcov\fR to calculate separate execution counts
|
||
|
|
for each line because there isn't separate code for each line. Hence
|
||
|
|
the \fBgcov\fR output looks like this if you compiled the program with
|
||
|
|
optimization:
|
||
|
|
.PP
|
||
|
|
.Vb 4
|
||
|
|
\& 100: 12:if (a != b)
|
||
|
|
\& 100: 13: c = 1;
|
||
|
|
\& 100: 14:else
|
||
|
|
\& 100: 15: c = 0;
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
The output shows that this block of code, combined by optimization,
|
||
|
|
executed 100 times. In one sense this result is correct, because there
|
||
|
|
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
|
||
|
|
many times the result was 1.
|
||
|
|
.PP
|
||
|
|
Inlineable functions can create unexpected line counts. Line counts are
|
||
|
|
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.
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
\&\fIfileA.o\fR and \fIfileB.o\fR both contain out of line bodies of a
|
||
|
|
particular inlineable function, they will also both contain coverage
|
||
|
|
counts for that function. When \fIfileA.o\fR and \fIfileB.o\fR are
|
||
|
|
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
|
||
|
|
the other. Unfortunately, it will not remove the coverage counters for
|
||
|
|
the unused function body. Hence when instrumented, all but one use of
|
||
|
|
that function will show zero counts.
|
||
|
|
.PP
|
||
|
|
If the function is inlined in several places, the block structure in
|
||
|
|
each location might not be the same. For instance, a condition might
|
||
|
|
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
|
||
|
|
same source lines, the line counts themselves might seem inconsistent.
|
||
|
|
.PP
|
||
|
|
Long-running applications can use the \f(CW\*(C`_\|_gcov_reset\*(C'\fR and \f(CW\*(C`_\|_gcov_dump\*(C'\fR
|
||
|
|
facilities to restrict profile collection to the program region of
|
||
|
|
interest. Calling \f(CW\*(C`_\|_gcov_reset(void)\*(C'\fR will clear all profile counters
|
||
|
|
to zero, and calling \f(CW\*(C`_\|_gcov_dump(void)\*(C'\fR will cause the profile information
|
||
|
|
collected at that point to be dumped to \fI.gcda\fR output files.
|
||
|
|
Instrumented applications use a static destructor with priority 99
|
||
|
|
to invoke the \f(CW\*(C`_\|_gcov_dump\*(C'\fR function. Thus \f(CW\*(C`_\|_gcov_dump\*(C'\fR
|
||
|
|
is executed after all user defined static destructors,
|
||
|
|
as well as handlers registered with \f(CW\*(C`atexit\*(C'\fR.
|
||
|
|
If an executable loads a dynamic shared object via dlopen functionality,
|
||
|
|
\&\fB\-Wl,\-\-dynamic\-list\-data\fR is needed to dump all profile data.
|
||
|
|
.PP
|
||
|
|
Profiling run-time library reports various errors related to profile
|
||
|
|
manipulation and profile saving. Errors are printed into standard error output
|
||
|
|
or \fB\s-1GCOV_ERROR_FILE\s0\fR file, if environment variable is used.
|
||
|
|
In order to terminate immediately after an errors occurs
|
||
|
|
set \fB\s-1GCOV_EXIT_AT_ERROR\s0\fR environment variable.
|
||
|
|
That can help users to find profile clashing which leads
|
||
|
|
to a misleading profile.
|
||
|
|
.SH "SEE ALSO"
|
||
|
|
.IX Header "SEE ALSO"
|
||
|
|
\&\fIgpl\fR\|(7), \fIgfdl\fR\|(7), \fIfsf\-funding\fR\|(7), \fIgcc\fR\|(1) and the Info entry for \fIgcc\fR.
|
||
|
|
.SH "COPYRIGHT"
|
||
|
|
.IX Header "COPYRIGHT"
|
||
|
|
Copyright (c) 1996\-2019 Free Software Foundation, Inc.
|
||
|
|
.PP
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.3 or
|
||
|
|
any later version published by the Free Software Foundation; with the
|
||
|
|
Invariant Sections being \*(L"\s-1GNU\s0 General Public License\*(R" and \*(L"Funding
|
||
|
|
Free Software\*(R", 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 \fIgfdl\fR\|(7) man page.
|
||
|
|
.PP
|
||
|
|
(a) The \s-1FSF\s0's Front-Cover Text is:
|
||
|
|
.PP
|
||
|
|
.Vb 1
|
||
|
|
\& A GNU Manual
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
(b) The \s-1FSF\s0's Back-Cover Text is:
|
||
|
|
.PP
|
||
|
|
.Vb 3
|
||
|
|
\& 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.
|
||
|
|
.Ve
|