629 lines
24 KiB
Groff
629 lines
24 KiB
Groff
|
.\" Automatically generated by Pod::Man 2.23 (Pod::Simple 3.14)
|
||
|
|
.\"
|
||
|
|
.\" Standard preamble:
|
||
|
|
.\" ========================================================================
|
||
|
|
.de Sp \" Vertical space (when we can't use .PP)
|
||
|
|
.if t .sp .5v
|
||
|
|
.if n .sp
|
||
|
|
..
|
||
|
|
.de Vb \" Begin verbatim text
|
||
|
|
.ft CW
|
||
|
|
.nf
|
||
|
|
.ne \\$1
|
||
|
|
..
|
||
|
|
.de Ve \" End verbatim text
|
||
|
|
.ft R
|
||
|
|
.fi
|
||
|
|
..
|
||
|
|
.\" Set up some character translations and predefined strings. \*(-- will
|
||
|
|
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
|
||
|
|
.\" double quote, and \*(R" will give a right double quote. \*(C+ will
|
||
|
|
.\" give a nicer C++. Capital omega is used to do unbreakable dashes and
|
||
|
|
.\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
|
||
|
|
.\" nothing in troff, for use with C<>.
|
||
|
|
.tr \(*W-
|
||
|
|
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
|
||
|
|
.ie n \{\
|
||
|
|
. ds -- \(*W-
|
||
|
|
. ds PI pi
|
||
|
|
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
|
||
|
|
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
|
||
|
|
. ds L" ""
|
||
|
|
. ds R" ""
|
||
|
|
. ds C` ""
|
||
|
|
. ds C' ""
|
||
|
|
'br\}
|
||
|
|
.el\{\
|
||
|
|
. ds -- \|\(em\|
|
||
|
|
. ds PI \(*p
|
||
|
|
. ds L" ``
|
||
|
|
. ds R" ''
|
||
|
|
'br\}
|
||
|
|
.\"
|
||
|
|
.\" Escape single quotes in literal strings from groff's Unicode transform.
|
||
|
|
.ie \n(.g .ds Aq \(aq
|
||
|
|
.el .ds Aq '
|
||
|
|
.\"
|
||
|
|
.\" If the F register is turned on, we'll generate index entries on stderr for
|
||
|
|
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
|
||
|
|
.\" entries marked with X<> in POD. Of course, you'll have to process the
|
||
|
|
.\" output yourself in some meaningful fashion.
|
||
|
|
.ie \nF \{\
|
||
|
|
. de IX
|
||
|
|
. tm Index:\\$1\t\\n%\t"\\$2"
|
||
|
|
..
|
||
|
|
. nr % 0
|
||
|
|
. rr F
|
||
|
|
.\}
|
||
|
|
.el \{\
|
||
|
|
. de IX
|
||
|
|
..
|
||
|
|
.\}
|
||
|
|
.\"
|
||
|
|
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
|
||
|
|
.\" Fear. Run. Save yourself. No user-serviceable parts.
|
||
|
|
. \" fudge factors for nroff and troff
|
||
|
|
.if n \{\
|
||
|
|
. ds #H 0
|
||
|
|
. ds #V .8m
|
||
|
|
. ds #F .3m
|
||
|
|
. ds #[ \f1
|
||
|
|
. ds #] \fP
|
||
|
|
.\}
|
||
|
|
.if t \{\
|
||
|
|
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
|
||
|
|
. ds #V .6m
|
||
|
|
. ds #F 0
|
||
|
|
. ds #[ \&
|
||
|
|
. ds #] \&
|
||
|
|
.\}
|
||
|
|
. \" simple accents for nroff and troff
|
||
|
|
.if n \{\
|
||
|
|
. ds ' \&
|
||
|
|
. ds ` \&
|
||
|
|
. ds ^ \&
|
||
|
|
. ds , \&
|
||
|
|
. ds ~ ~
|
||
|
|
. ds /
|
||
|
|
.\}
|
||
|
|
.if t \{\
|
||
|
|
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
|
||
|
|
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
|
||
|
|
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
|
||
|
|
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
|
||
|
|
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
|
||
|
|
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
|
||
|
|
.\}
|
||
|
|
. \" troff and (daisy-wheel) nroff accents
|
||
|
|
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
|
||
|
|
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
|
||
|
|
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
|
||
|
|
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
|
||
|
|
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
|
||
|
|
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
|
||
|
|
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
|
||
|
|
.ds ae a\h'-(\w'a'u*4/10)'e
|
||
|
|
.ds Ae A\h'-(\w'A'u*4/10)'E
|
||
|
|
. \" corrections for vroff
|
||
|
|
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
|
||
|
|
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
|
||
|
|
. \" for low resolution devices (crt and lpr)
|
||
|
|
.if \n(.H>23 .if \n(.V>19 \
|
||
|
|
\{\
|
||
|
|
. ds : e
|
||
|
|
. ds 8 ss
|
||
|
|
. ds o a
|
||
|
|
. ds d- d\h'-1'\(ga
|
||
|
|
. ds D- D\h'-1'\(hy
|
||
|
|
. ds th \o'bp'
|
||
|
|
. ds Th \o'LP'
|
||
|
|
. ds ae ae
|
||
|
|
. ds Ae AE
|
||
|
|
.\}
|
||
|
|
.rm #[ #] #H #V #F C
|
||
|
|
.\" ========================================================================
|
||
|
|
.\"
|
||
|
|
.IX Title "GCOV 1"
|
||
|
|
.TH GCOV 1 "2011-06-23" "gcc-4.1.3" "GNU"
|
||
|
|
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
|
||
|
|
.\" way too many mistakes in technical documents.
|
||
|
|
.if n .ad l
|
||
|
|
.nh
|
||
|
|
.SH "NAME"
|
||
|
|
gcov \- coverage testing tool
|
||
|
|
.SH "SYNOPSIS"
|
||
|
|
.IX Header "SYNOPSIS"
|
||
|
|
gcov [\fB\-v\fR|\fB\-\-version\fR] [\fB\-h\fR|\fB\-\-help\fR]
|
||
|
|
[\fB\-a\fR|\fB\-\-all\-blocks\fR]
|
||
|
|
[\fB\-b\fR|\fB\-\-branch\-probabilities\fR]
|
||
|
|
[\fB\-c\fR|\fB\-\-branch\-counts\fR]
|
||
|
|
[\fB\-n\fR|\fB\-\-no\-output\fR]
|
||
|
|
[\fB\-l\fR|\fB\-\-long\-file\-names\fR]
|
||
|
|
[\fB\-p\fR|\fB\-\-preserve\-paths\fR]
|
||
|
|
[\fB\-f\fR|\fB\-\-function\-summaries\fR]
|
||
|
|
[\fB\-o\fR|\fB\-\-object\-directory\fR \fIdirectory|file\fR]
|
||
|
|
[\fB\-u\fR|\fB\-\-unconditional\-branches\fR]
|
||
|
|
\fIsourcefile\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 "\(bu" 4
|
||
|
|
how often each line of code executes
|
||
|
|
.IP "\(bu" 4
|
||
|
|
what lines of code are actually executed
|
||
|
|
.IP "\(bu" 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\-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\-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\-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\-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\-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. If you use the \fB\-p\fR option, both the including and
|
||
|
|
included file names will be complete path names.
|
||
|
|
.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 \fI..\fR
|
||
|
|
components renamed to \fB^\fR. This is useful if sourcefiles are in several
|
||
|
|
different directories. It also affects the \fB\-l\fR option.
|
||
|
|
.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\-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
|
||
|
|
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.
|
||
|
|
.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.
|
||
|
|
.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 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
|
||
|
|
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 and \fB#####\fR for lines which were never executed.
|
||
|
|
Some lines of information at the start have \fIline_number\fR of zero.
|
||
|
|
.PP
|
||
|
|
The 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 two
|
||
|
|
special \s-1GCC\s0 options: \fB\-fprofile\-arcs \-ftest\-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.c\fR, this
|
||
|
|
is what you see when you use the basic \fBgcov\fR facility:
|
||
|
|
.PP
|
||
|
|
.Vb 5
|
||
|
|
\& $ gcc \-fprofile\-arcs \-ftest\-coverage tmp.c
|
||
|
|
\& $ a.out
|
||
|
|
\& $ gcov tmp.c
|
||
|
|
\& 90.00% of 10 source lines executed in file tmp.c
|
||
|
|
\& Creating tmp.c.gcov.
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
The file \fItmp.c.gcov\fR contains output from \fBgcov\fR.
|
||
|
|
Here is a sample:
|
||
|
|
.PP
|
||
|
|
.Vb 10
|
||
|
|
\& \-: 0:Source:tmp.c
|
||
|
|
\& \-: 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\en");
|
||
|
|
\& \-: 14: else
|
||
|
|
\& 1: 15: printf ("Success\en");
|
||
|
|
\& 1: 16: return 0;
|
||
|
|
\& \-: 17:}
|
||
|
|
.Ve
|
||
|
|
.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.c
|
||
|
|
\& \-: 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\en");
|
||
|
|
\& $$$$$: 13\-block 0
|
||
|
|
\& \-: 14: else
|
||
|
|
\& 1: 15: printf ("Success\en");
|
||
|
|
\& 1: 15\-block 0
|
||
|
|
\& 1: 16: return 0;
|
||
|
|
\& 1: 16\-block 0
|
||
|
|
\& \-: 17:}
|
||
|
|
.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 13 contains a basic block that was not executed.
|
||
|
|
.PP
|
||
|
|
When you use the \fB\-b\fR option, your output looks like this:
|
||
|
|
.PP
|
||
|
|
.Vb 6
|
||
|
|
\& $ 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.
|
||
|
|
.Ve
|
||
|
|
.PP
|
||
|
|
Here is a sample of a resulting \fItmp.c.gcov\fR file:
|
||
|
|
.PP
|
||
|
|
.Vb 10
|
||
|
|
\& \-: 0:Source:tmp.c
|
||
|
|
\& \-: 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++)
|
||
|
|
\& branch 0 taken 91% (fallthrough)
|
||
|
|
\& branch 1 taken 9%
|
||
|
|
\& 10: 10: total += i;
|
||
|
|
\& \-: 11:
|
||
|
|
\& 1: 12: if (total != 45)
|
||
|
|
\& branch 0 taken 0% (fallthrough)
|
||
|
|
\& branch 1 taken 100%
|
||
|
|
\& #####: 13: printf ("Failure\en");
|
||
|
|
\& call 0 never executed
|
||
|
|
\& \-: 14: else
|
||
|
|
\& 1: 15: printf ("Success\en");
|
||
|
|
\& call 0 called 1 returned 100%
|
||
|
|
\& 1: 16: return 0;
|
||
|
|
\& \-: 17:}
|
||
|
|
.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 two special \s-1GCC\s0 options:
|
||
|
|
\&\fB\-fprofile\-arcs \-ftest\-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.
|
||
|
|
.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, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2005
|
||
|
|
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 1.2 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
|