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diff --git a/man-pages/gcov3.1 b/man-pages/gcov3.1 new file mode 100644 index 00000000000..f68ba8afbf2 --- /dev/null +++ b/man-pages/gcov3.1 @@ -0,0 +1,453 @@ +.\" Automatically generated by Pod::Man version 1.15 +.\" Wed Jun 19 19:36:24 2002 +.\" +.\" Standard preamble: +.\" ====================================================================== +.de Sh \" Subsection heading +.br +.if t .Sp +.ne 5 +.PP +\fB\\$1\fR +.PP +.. +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Ip \" List item +.br +.ie \\n(.$>=3 .ne \\$3 +.el .ne 3 +.IP "\\$1" \\$2 +.. +.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. | will give a +.\" real vertical bar. \*(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-|\(bv\*(Tr +.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\} +.\" +.\" If the F register is turned on, we'll generate index entries on stderr +.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and +.\" index entries marked with X<> in POD. Of course, you'll have to process +.\" the output yourself in some meaningful fashion. +.if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. nr % 0 +. rr F +.\} +.\" +.\" For nroff, turn off justification. 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Use it in concert with \s-1GCC\s0 +to analyze your programs to help create more efficient, faster +running code. 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\-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. +.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. +.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\fR" 4 +.IX Item "-o directory" +.PD 0 +.Ip "\fB\*(--object-directory\fR \fIdirectory\fR" 4 +.IX Item "object-directory directory" +.PD +The directory where the object files live. Gcov will search for \fI.bb\fR, +\&\fI.bbg\fR, and \fI.da\fR files in this directory. +.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 source code 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.da\fR +file will be placed in the source 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 +\& 87.50% of 8 source lines executed in file tmp.c +\& Creating tmp.c.gcov. +.Ve +The file \fItmp.c.gcov\fR contains output from \fBgcov\fR. +Here is a sample: +.PP +.Vb 3 +\& main() +\& { +\& 1 int i, total; +.Ve +.Vb 1 +\& 1 total = 0; +.Ve +.Vb 2 +\& 11 for (i = 0; i < 10; i++) +\& 10 total += i; +.Ve +.Vb 5 +\& 1 if (total != 45) +\& ###### printf ("Failure\en"); +\& else +\& 1 printf ("Success\en"); +\& 1 } +.Ve +When you use the \fB\-b\fR option, your output looks like this: +.PP +.Vb 6 +\& $ gcov -b tmp.c +\& 87.50% of 8 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 +Here is a sample of a resulting \fItmp.c.gcov\fR file: +.PP +.Vb 3 +\& main() +\& { +\& 1 int i, total; +.Ve +.Vb 1 +\& 1 total = 0; +.Ve +.Vb 5 +\& 11 for (i = 0; i < 10; i++) +\& branch 0 taken = 91% +\& branch 1 taken = 100% +\& branch 2 taken = 100% +\& 10 total += i; +.Ve +.Vb 9 +\& 1 if (total != 45) +\& branch 0 taken = 100% +\& ###### printf ("Failure\en"); +\& call 0 never executed +\& branch 1 never executed +\& else +\& 1 printf ("Success\en"); +\& call 0 returns = 100% +\& 1 } +.Ve +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 ``never executed'' 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 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.da\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 \fIrun\fR\|(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.da\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.da\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. +.Sh "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 +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 if (a != b) +\& 100 c = 1; +\& 100 else +\& 100 c = 0; +.Ve +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. +.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 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 1.1 or +any later version published by the Free Software Foundation; with the +Invariant Sections being ``\s-1GNU\s0 General Public License'' and ``Funding +Free Software'', the Front-Cover texts being (a) (see below), and with +the Back-Cover Texts being (b) (see below). A copy of the license is +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 +(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 |