fd939e46c9
contrib: * texi2pod.pl: Handle @option and @env. gcc: * configure.in: Require at least texinfo 4.0. Check for whether Pod::Man is sufficiently recent to regenerate GCC manpages. * configure: Regenerate. * Makefile.in (TEXI2POD): Call perl explicitly rather than relying on #!. (GENERATED_MANPAGES): Define. (generated-manpages): New target. Depend on cpp.1 as well as gcov.1. (install-man): Depend on $(GENERATED_MANPAGES) (defined by configure to generated-manpages or empty) rather than on the manpages directly. Remove execute permission from installed gcov.1 as well as cpp.1. * cpp.1, gcov.1: Regenerate. From-SVN: r38668
415 lines
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415 lines
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Groff
.\" Automatically generated by Pod::Man version 1.1
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.\" Wed Jan 3 20:06:14 2001
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.\"
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.\" Standard preamble:
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.\" ======================================================================
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.de Sh \" Subsection heading
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.\" index entries marked with X<> in POD. Of course, you'll have to process
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. de IX
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.\" ======================================================================
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.\"
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.IX Title "GCOV 1"
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.TH GCOV 1 "gcc-2.97" "2001-01-03" "GNU"
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.UC
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.SH "NAME"
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gcov \- coverage testing tool
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.SH "SYNOPSIS"
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.IX Header "SYNOPSIS"
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gcov [\fB\-b\fR] [\fB\-c\fR] [\fB\-v\fR] [\fB\-n\fR] [\fB\-l\fR] [\fB\-f\fR] [\fB\-o\fR \fIdirectory\fR] \fIsourcefile\fR
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.SH "DESCRIPTION"
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.IX Header "DESCRIPTION"
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\&\f(CW\*(C`gcov\*(C'\fR is a test coverage program. Use it in concert with \s-1GNU\s0
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\&\s-1CC\s0 to analyze your programs to help create more efficient, faster
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running code. You can use \f(CW\*(C`gcov\*(C'\fR as a profiling tool to help
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discover where your optimization efforts will best affect your code. You
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can also use \f(CW\*(C`gcov\*(C'\fR along with the other profiling tool,
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\&\f(CW\*(C`gprof\*(C'\fR, to assess which parts of your code use the greatest amount
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of computing time.
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.PP
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Profiling tools help you analyze your code's performance. Using a
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profiler such as \f(CW\*(C`gcov\*(C'\fR or \f(CW\*(C`gprof\*(C'\fR, you can find out some
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basic performance statistics, such as:
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.Ip "\(bu" 4
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how often each line of code executes
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.Ip "\(bu" 4
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what lines of code are actually executed
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.Ip "\(bu" 4
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how much computing time each section of code uses
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.PP
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Once you know these things about how your code works when compiled, you
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can look at each module to see which modules should be optimized.
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\&\f(CW\*(C`gcov\*(C'\fR helps you determine where to work on optimization.
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.PP
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Software developers also use coverage testing in concert with
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testsuites, to make sure software is actually good enough for a release.
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Testsuites can verify that a program works as expected; a coverage
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program tests to see how much of the program is exercised by the
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testsuite. Developers can then determine what kinds of test cases need
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to be added to the testsuites to create both better testing and a better
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final product.
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.PP
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You should compile your code without optimization if you plan to use
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\&\f(CW\*(C`gcov\*(C'\fR because the optimization, by combining some lines of code
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into one function, may not give you as much information as you need to
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look for `hot spots' where the code is using a great deal of computer
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time. Likewise, because \f(CW\*(C`gcov\*(C'\fR accumulates statistics by line (at
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the lowest resolution), it works best with a programming style that
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places only one statement on each line. If you use complicated macros
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that expand to loops or to other control structures, the statistics are
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less helpful\-\-\-they only report on the line where the macro call
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appears. If your complex macros behave like functions, you can replace
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them with inline functions to solve this problem.
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.PP
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\&\f(CW\*(C`gcov\*(C'\fR creates a logfile called \fI\fIsourcefile\fI.gcov\fR which
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indicates how many times each line of a source file \fI\fIsourcefile\fI.c\fR
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has executed. You can use these logfiles along with \f(CW\*(C`gprof\*(C'\fR to aid
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in fine-tuning the performance of your programs. \f(CW\*(C`gprof\*(C'\fR gives
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timing information you can use along with the information you get from
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\&\f(CW\*(C`gcov\*(C'\fR.
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.PP
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\&\f(CW\*(C`gcov\*(C'\fR works only on code compiled with \s-1GNU\s0 \s-1CC\s0. It is not
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compatible with any other profiling or test coverage mechanism.
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.SH "OPTIONS"
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.IX Header "OPTIONS"
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.if n .Ip "\f(CW""\-b""\fR" 4
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.el .Ip "\f(CW\-b\fR" 4
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.IX Item "-b"
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Write branch frequencies to the output file, and write branch summary
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info to the standard output. This option allows you to see how often
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each branch in your program was taken.
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.if n .Ip "\f(CW""\-c""\fR" 4
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.el .Ip "\f(CW\-c\fR" 4
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.IX Item "-c"
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Write branch frequencies as the number of branches taken, rather than
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the percentage of branches taken.
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.if n .Ip "\f(CW""\-v""\fR" 4
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.el .Ip "\f(CW\-v\fR" 4
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.IX Item "-v"
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Display the \f(CW\*(C`gcov\*(C'\fR version number (on the standard error stream).
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.if n .Ip "\f(CW""\-n""\fR" 4
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.el .Ip "\f(CW\-n\fR" 4
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.IX Item "-n"
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Do not create the \f(CW\*(C`gcov\*(C'\fR output file.
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.if n .Ip "\f(CW""\-l""\fR" 4
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.el .Ip "\f(CW\-l\fR" 4
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.IX Item "-l"
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Create long file names for included source files. For example, if the
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header file \fBx.h\fR contains code, and was included in the file
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\&\fBa.c\fR, then running \f(CW\*(C`gcov\*(C'\fR on the file \fBa.c\fR will produce
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an output file called \fBa.c.x.h.gcov\fR instead of \fBx.h.gcov\fR.
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This can be useful if \fBx.h\fR is included in multiple source files.
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.if n .Ip "\f(CW""\-f""\fR" 4
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.el .Ip "\f(CW\-f\fR" 4
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.IX Item "-f"
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Output summaries for each function in addition to the file level summary.
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.if n .Ip "\f(CW""\-o""\fR" 4
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.el .Ip "\f(CW\-o\fR" 4
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.IX Item "-o"
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The directory where the object files live. Gcov will search for \f(CW\*(C`.bb\*(C'\fR,
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\&\f(CW\*(C`.bbg\*(C'\fR, and \f(CW\*(C`.da\*(C'\fR files in this directory.
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.PP
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When using \f(CW\*(C`gcov\*(C'\fR, you must first compile your program with two
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special \s-1GNU\s0 \s-1CC\s0 options: \fB\-fprofile-arcs \-ftest-coverage\fR.
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This tells the compiler to generate additional information needed by
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gcov (basically a flow graph of the program) and also includes
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additional code in the object files for generating the extra profiling
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information needed by gcov. These additional files are placed in the
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directory where the source code is located.
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.PP
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Running the program will cause profile output to be generated. For each
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source file compiled with \-fprofile-arcs, an accompanying \f(CW\*(C`.da\*(C'\fR
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file will be placed in the source directory.
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.PP
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Running \f(CW\*(C`gcov\*(C'\fR with your program's source file names as arguments
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will now produce a listing of the code along with frequency of execution
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for each line. For example, if your program is called \fBtmp.c\fR, this
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is what you see when you use the basic \f(CW\*(C`gcov\*(C'\fR facility:
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.PP
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.Vb 5
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\& $ gcc -fprofile-arcs -ftest-coverage tmp.c
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\& $ a.out
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\& $ gcov tmp.c
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\& 87.50% of 8 source lines executed in file tmp.c
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\& Creating tmp.c.gcov.
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.Ve
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The file \fItmp.c.gcov\fR contains output from \f(CW\*(C`gcov\*(C'\fR.
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Here is a sample:
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.PP
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.Vb 3
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\& main()
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\& {
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\& 1 int i, total;
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.Ve
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.Vb 1
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\& 1 total = 0;
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.Ve
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.Vb 2
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\& 11 for (i = 0; i < 10; i++)
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\& 10 total += i;
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.Ve
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.Vb 5
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\& 1 if (total != 45)
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\& ###### printf ("Failure\en");
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\& else
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\& 1 printf ("Success\en");
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\& 1 }
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.Ve
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When you use the \fB\-b\fR option, your output looks like this:
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.PP
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.Vb 6
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\& $ gcov -b tmp.c
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\& 87.50% of 8 source lines executed in file tmp.c
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\& 80.00% of 5 branches executed in file tmp.c
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\& 80.00% of 5 branches taken at least once in file tmp.c
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\& 50.00% of 2 calls executed in file tmp.c
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\& Creating tmp.c.gcov.
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.Ve
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Here is a sample of a resulting \fItmp.c.gcov\fR file:
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.PP
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.Vb 3
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\& main()
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\& {
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\& 1 int i, total;
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.Ve
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.Vb 1
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\& 1 total = 0;
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.Ve
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.Vb 5
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\& 11 for (i = 0; i < 10; i++)
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\& branch 0 taken = 91%
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\& branch 1 taken = 100%
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\& branch 2 taken = 100%
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\& 10 total += i;
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.Ve
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.Vb 9
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\& 1 if (total != 45)
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\& branch 0 taken = 100%
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\& ###### printf ("Failure\en");
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\& call 0 never executed
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\& branch 1 never executed
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\& else
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\& 1 printf ("Success\en");
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\& call 0 returns = 100%
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\& 1 }
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.Ve
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For each basic block, a line is printed after the last line of the basic
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block describing the branch or call that ends the basic block. There can
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be multiple branches and calls listed for a single source line if there
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are multiple basic blocks that end on that line. In this case, the
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branches and calls are each given a number. There is no simple way to map
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these branches and calls back to source constructs. In general, though,
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the lowest numbered branch or call will correspond to the leftmost construct
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on the source line.
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.PP
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For a branch, if it was executed at least once, then a percentage
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indicating the number of times the branch was taken divided by the
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number of times the branch was executed will be printed. Otherwise, the
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message ``never executed'' is printed.
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.PP
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For a call, if it was executed at least once, then a percentage
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|
indicating the number of times the call returned divided by the number
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of times the call was executed will be printed. This will usually be
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100%, but may be less for functions call \f(CW\*(C`exit\*(C'\fR or \f(CW\*(C`longjmp\*(C'\fR,
|
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and thus may not return every time they are called.
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.PP
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The execution counts are cumulative. If the example program were
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executed again without removing the \f(CW\*(C`.da\*(C'\fR file, the count for the
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number of times each line in the source was executed would be added to
|
|
the results of the previous \fIrun\fR\|(s). This is potentially useful in
|
|
several ways. For example, it could be used to accumulate data over a
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|
number of program runs as part of a test verification suite, or to
|
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provide more accurate long-term information over a large number of
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program runs.
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.PP
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The data in the \f(CW\*(C`.da\*(C'\fR files is saved immediately before the program
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exits. For each source file compiled with \-fprofile-arcs, the profiling
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code first attempts to read in an existing \f(CW\*(C`.da\*(C'\fR file; if the file
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doesn't match the executable (differing number of basic block counts) it
|
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will ignore the contents of the file. It then adds in the new execution
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counts and finally writes the data to the file.
|
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.if n .Sh "Using \f(CW""gcov""\fP with \s-1GCC\s0 Optimization"
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.el .Sh "Using \f(CWgcov\fP with \s-1GCC\s0 Optimization"
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.IX Subsection "Using gcov with GCC Optimization"
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If you plan to use \f(CW\*(C`gcov\*(C'\fR to help optimize your code, you must
|
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first compile your program with two special \s-1GNU\s0 \s-1CC\s0 options:
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\&\fB\-fprofile-arcs \-ftest-coverage\fR. Aside from that, you can use any
|
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other \s-1GNU\s0 \s-1CC\s0 options; but if you want to prove that every single line
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in your program was executed, you should not compile with optimization
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|
at the same time. On some machines the optimizer can eliminate some
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simple code lines by combining them with other lines. For example, code
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like this:
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.PP
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.Vb 4
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\& if (a != b)
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\& c = 1;
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\& else
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\& c = 0;
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.Ve
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can be compiled into one instruction on some machines. In this case,
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there is no way for \f(CW\*(C`gcov\*(C'\fR to calculate separate execution counts
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for each line because there isn't separate code for each line. Hence
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the \f(CW\*(C`gcov\*(C'\fR output looks like this if you compiled the program with
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optimization:
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.PP
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.Vb 4
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\& 100 if (a != b)
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\& 100 c = 1;
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\& 100 else
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\& 100 c = 0;
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.Ve
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The output shows that this block of code, combined by optimization,
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executed 100 times. In one sense this result is correct, because there
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was only one instruction representing all four of these lines. However,
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the output does not indicate how many times the result was 0 and how
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many times the result was 1.
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.SH "SEE ALSO"
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.IX Header "SEE ALSO"
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\&\fIgcc\fR\|(1) and the Info entry for \fIgcc\fR.
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.SH "COPYRIGHT"
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.IX Header "COPYRIGHT"
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Copyright (c) 1996, 1997, 1999, 2000 Free Software Foundation, Inc.
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.PP
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Permission is granted to make and distribute verbatim copies of this
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manual provided the copyright notice and this permission notice are
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preserved on all copies.
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.PP
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Permission is granted to copy and distribute modified versions of this
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manual under the conditions for verbatim copying, provided also that the
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entire resulting derived work is distributed under the terms of a
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permission notice identical to this one.
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.PP
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Permission is granted to copy and distribute translations of this manual
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into another language, under the above conditions for modified versions,
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except that this permission notice may be included in translations
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approved by the Free Software Foundation instead of in the original
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English.
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