diff options
Diffstat (limited to 'gcc-4.9/gcc/doc/gcov.1')
| -rw-r--r-- | gcc-4.9/gcc/doc/gcov.1 | 733 |
1 files changed, 0 insertions, 733 deletions
diff --git a/gcc-4.9/gcc/doc/gcov.1 b/gcc-4.9/gcc/doc/gcov.1 deleted file mode 100644 index 8de32cb85..000000000 --- a/gcc-4.9/gcc/doc/gcov.1 +++ /dev/null @@ -1,733 +0,0 @@ -.\" Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28) -.\" -.\" 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" '' -. ds C` -. ds C' -'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. -.\" -.\" Avoid warning from groff about undefined register 'F'. -.de IX -.. -.nr rF 0 -.if \n(.g .if rF .nr rF 1 -.if (\n(rF:(\n(.g==0)) \{ -. if \nF \{ -. de IX -. tm Index:\\$1\t\\n%\t"\\$2" -.. -. if !\nF==2 \{ -. nr % 0 -. nr F 2 -. \} -. \} -.\} -.rr rF -.\" -.\" 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 "2014-04-22" "gcc-4.9.0" "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\-d\fR|\fB\-\-display\-progress\fR] - [\fB\-f\fR|\fB\-\-function\-summaries\fR] - [\fB\-i\fR|\fB\-\-intermediate\-format\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\-r\fR|\fB\-\-relative\-only\fR] - [\fB\-s\fR|\fB\-\-source\-prefix\fR \fIdirectory\fR] - [\fB\-u\fR|\fB\-\-unconditional\-branches\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 "\(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 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\-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\-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\-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 -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\-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\-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\-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\-i\fR" 4 -.IX Item "-i" -.PD 0 -.IP "\fB\-\-intermediate\-format\fR" 4 -.IX Item "--intermediate-format" -.PD -Output gcov file in an easy-to-parse intermediate text format that can -be used by \fBlcov\fR or other tools. The output is a single -\&\fI.gcov\fR file per \fI.gcda\fR file. No source code is required. -.Sp -The format of the intermediate \fI.gcov\fR file is plain text with -one entry per line -.Sp -.Vb 4 -\& file:<source_file_name> -\& function:<line_number>,<execution_count>,<function_name> -\& lcount:<line number>,<execution_count> -\& branch:<line_number>,<branch_coverage_type> -\& -\& Where the <branch_coverage_type> is -\& notexec (Branch not executed) -\& taken (Branch executed and taken) -\& nottaken (Branch executed, but not taken) -\& -\& There can be multiple <file> entries in an intermediate gcov -\& file. All entries following a <file> pertain to that source file -\& until the next <file> entry. -.Ve -.Sp -Here is a sample when \fB\-i\fR is used in conjunction with \fB\-b\fR option: -.Sp -.Vb 9 -\& file:array.cc -\& function:11,1,_Z3sumRKSt6vectorIPiSaIS0_EE -\& function:22,1,main -\& lcount:11,1 -\& lcount:12,1 -\& lcount:14,1 -\& branch:14,taken -\& lcount:26,1 -\& branch:28,nottaken -.Ve -.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. -.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. -.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 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. -.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. -.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\-2014 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 |