| 1 | Sun Feb 5 16:09:16 1995
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| 2 |
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| 3 | This file documents the changes and new features available with this
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| 4 | version of GNU gprof.
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| 5 |
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| 6 | * New Features
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| 7 |
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| 8 | o Long options
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| 9 |
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| 10 | o Supports generalized file format, without breaking backward compatibility:
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| 11 | new file format supports basic-block execution counts and non-realtime
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| 12 | histograms (see below)
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| 13 |
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| 14 | o Supports profiling at the line level: flat profiles, call-graph profiles,
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| 15 | and execution-counts can all be displayed at a level that identifies
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| 16 | individual lines rather than just functions
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| 17 |
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| 18 | o Test-coverage support (similar to Sun tcov program): source files
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| 19 | can be annotated with the number of times a function was invoked
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| 20 | or with the number of times each basic-block in a function was
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| 21 | executed
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| 22 |
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| 23 | o Generalized histograms: not just execution-time, but arbitrary
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| 24 | histograms are support (for example, performance counter based
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| 25 | profiles)
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| 26 |
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| 27 | o Powerful mechanism to select data to be included/excluded from
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| 28 | analysis and/or output
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| 29 |
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| 30 | o Support for DEC OSF/1 v3.0
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| 31 |
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| 32 | o Full cross-platform profiling support: gprof uses BFD to support
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| 33 | arbitrary, non-native object file formats and non-native byte-orders
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| 34 | (this feature has not been tested yet)
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| 35 |
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| 36 | o In the call-graph function index, static function names are now
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| 37 | printed together with the filename in which the function was defined
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| 38 | (required bfd_find_nearest_line() support and symbolic debugging
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| 39 | information to be present in the executable file)
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| 40 |
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| 41 | o Major overhaul of source code (compiles cleanly with -Wall, etc.)
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| 42 |
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| 43 | * Supported Platforms
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| 44 |
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| 45 | The current version is known to work on:
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| 46 |
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| 47 | o DEC OSF/1 v3.0
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| 48 | All features supported.
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| 49 |
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| 50 | o SunOS 4.1.x
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| 51 | All features supported.
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| 52 |
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| 53 | o Solaris 2.3
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| 54 | Line-level profiling unsupported because bfd_find_nearest_line()
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| 55 | is not fully implemented for Elf binaries.
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| 56 |
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| 57 | o HP-UX 9.01
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| 58 | Line-level profiling unsupported because bfd_find_nearest_line()
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| 59 | is not fully implemented for SOM binaries.
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| 60 |
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| 61 | * Detailed Description
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| 62 |
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| 63 | ** User Interface Changes
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| 64 |
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| 65 | The command-line interface is backwards compatible with earlier
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| 66 | versions of GNU gprof and Berkeley gprof. The only exception is
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| 67 | the option to delete arcs from the call graph. The old syntax
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| 68 | was:
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| 69 |
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| 70 | -k fromname toname
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| 71 |
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| 72 | while the new syntax is:
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| 73 |
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| 74 | -k fromname/toname
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| 75 |
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| 76 | This change was necessary to be compatible with long-option parsing.
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| 77 | Also, "fromname" and "toname" can now be arbitrary symspecs rather
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| 78 | than just function names (see below for an explanation of symspecs).
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| 79 | For example, option "-k gprof.c/" suppresses all arcs due to calls out
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| 80 | of file "gprof.c".
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| 81 |
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| 82 | *** Sym Specs
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| 83 |
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| 84 | It is often necessary to apply gprof only to specific parts of a
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| 85 | program. GNU gprof has a simple but powerful mechanism to achieve
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| 86 | this. So called {\em symspecs\/} provide the foundation for this
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| 87 | mechanism. A symspec selects the parts of a profiled program to which
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| 88 | an operation should be applied to. The syntax of a symspec is
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| 89 | simple:
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| 90 |
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| 91 | filename_containing_a_dot
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| 92 | | funcname_not_containing_a_dot
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| 93 | | linenumber
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| 94 | | ( [ any_filename ] `:' ( any_funcname | linenumber ) )
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| 95 |
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| 96 | Here are some examples:
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| 97 |
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| 98 | main.c Selects everything in file "main.c"---the
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| 99 | dot in the string tells gprof to interpret
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| 100 | the string as a filename, rather than as
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| 101 | a function name. To select a file whose
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| 102 | name does contain a dot, a trailing colon
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| 103 | should be specified. For example, "odd:" is
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| 104 | interpreted as the file named "odd".
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| 105 |
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| 106 | main Selects all functions named "main". Notice
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| 107 | that there may be multiple instances of the
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| 108 | same function name because some of the
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| 109 | definitions may be local (i.e., static).
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| 110 | Unless a function name is unique in a program,
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| 111 | you must use the colon notation explained
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| 112 | below to specify a function from a specific
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| 113 | source file. Sometimes, functionnames contain
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| 114 | dots. In such cases, it is necessar to
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| 115 | add a leading colon to the name. For example,
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| 116 | ":.mul" selects function ".mul".
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| 117 |
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| 118 | main.c:main Selects function "main" in file "main.c".
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| 119 |
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| 120 | main.c:134 Selects line 134 in file "main.c".
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| 121 |
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| 122 | IMPLEMENTATION NOTE: The source code uses the type sym_id for symspecs.
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| 123 | At some point, this probably ought to be changed to "sym_spec" to make
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| 124 | reading the code easier.
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| 125 |
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| 126 | *** Long options
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| 127 |
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| 128 | GNU gprof now supports long options. The following is a list of all
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| 129 | supported options. Options that are listed without description
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| 130 | operate in the same manner as the corresponding option in older
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| 131 | versions of gprof.
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| 132 |
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| 133 | Short Form: Long Form:
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| 134 | ----------- ----------
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| 135 | -l --line
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| 136 | Request profiling at the line-level rather
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| 137 | than just at the function level. Source
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| 138 | lines are identified by symbols of the form:
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| 139 |
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| 140 | func (file:line)
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| 141 |
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| 142 | where "func" is the function name, "file" is the
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| 143 | file name and "line" is the line-number that
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| 144 | corresponds to the line.
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| 145 |
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| 146 | To work properly, the binary must contain symbolic
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| 147 | debugging information. This means that the source
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| 148 | have to be translated with option "-g" specified.
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| 149 | Functions for which there is no symbolic debugging
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| 150 | information available are treated as if "--line"
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| 151 | had not been specified. However, the line number
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| 152 | printed with such symbols is usually incorrect
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| 153 | and should be ignored.
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| 154 |
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| 155 | -a --no-static
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| 156 | -A[symspec] --annotated-source[=symspec]
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| 157 | Request output in the form of annotated source
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| 158 | files. If "symspec" is specified, print output only
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| 159 | for symbols selected by "symspec". If the option
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| 160 | is specified multiple times, annotated output is
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| 161 | generated for the union of all symspecs.
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| 162 |
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| 163 | Examples:
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| 164 |
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| 165 | -A Prints annotated source for all
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| 166 | source files.
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| 167 | -Agprof.c Prints annotated source for file
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| 168 | gprof.c.
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| 169 | -Afoobar Prints annotated source for files
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| 170 | containing a function named "foobar".
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| 171 | The entire file will be printed, but
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| 172 | only the function itself will be
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| 173 | annotated with profile data.
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| 174 |
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| 175 | -J[symspec] --no-annotated-source[=symspec]
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| 176 | Suppress annotated source output. If specified
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| 177 | without argument, annotated output is suppressed
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| 178 | completely. With an argument, annotated output
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| 179 | is suppressed only for the symbols selected by
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| 180 | "symspec". If the option is specified multiple
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| 181 | times, annotated output is suppressed for the
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| 182 | union of all symspecs. This option has lower
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| 183 | precedence than --annotated-source
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| 184 |
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| 185 | -p[symspec] --flat-profile[=symspec]
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| 186 | Request output in the form of a flat profile
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| 187 | (unless any other output-style option is specified,
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| 188 | this option is turned on by default). If
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| 189 | "symspec" is specified, include only symbols
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| 190 | selected by "symspec" in flat profile. If the
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| 191 | option is specified multiple times, the flat
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| 192 | profile includes symbols selected by the union
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| 193 | of all symspecs.
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| 194 |
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| 195 | -P[symspec] --no-flat-profile[=symspec]
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| 196 | Suppress output in the flat profile. If given
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| 197 | without an argument, the flat profile is suppressed
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| 198 | completely. If "symspec" is specified, suppress
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| 199 | the selected symbols in the flat profile. If the
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| 200 | option is specified multiple times, the union of
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| 201 | the selected symbols is suppressed. This option
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| 202 | has lower precedence than --flat-profile.
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| 203 |
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| 204 | -q[symspec] --graph[=symspec]
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| 205 | Request output in the form of a call-graph
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| 206 | (unless any other output-style option is specified,
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| 207 | this option is turned on by default). If "symspec"
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| 208 | is specified, include only symbols selected by
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| 209 | "symspec" in the call-graph. If the option is
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| 210 | specified multiple times, the call-graph includes
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| 211 | symbols selected by the union of all symspecs.
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| 212 |
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| 213 | -Q[symspec] --no-graph[=symspec]
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| 214 | Suppress output in the call-graph. If given without
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| 215 | an argument, the call-graph is suppressed completely.
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| 216 | With a "symspec", suppress the selected symbols
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| 217 | from the call-graph. If the option is specified
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| 218 | multiple times, the union of the selected symbols
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| 219 | is suppressed. This option has lower precedence
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| 220 | than --graph.
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| 221 |
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| 222 | -C[symspec] --exec-counts[=symspec]
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| 223 | Request output in the form of execution counts.
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| 224 | If "symspec" is present, include only symbols
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| 225 | selected by "symspec" in the execution count
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| 226 | listing. If the option is specified multiple
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| 227 | times, the execution count listing includes
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| 228 | symbols selected by the union of all symspecs.
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| 229 |
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| 230 | -Z[symspec] --no-exec-counts[=symspec]
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| 231 | Suppress output in the execution count listing.
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| 232 | If given without an argument, the listing is
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| 233 | suppressed completely. With a "symspec", suppress
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| 234 | the selected symbols from the call-graph. If the
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| 235 | option is specified multiple times, the union of
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| 236 | the selected symbols is suppressed. This option
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| 237 | has lower precedence than --exec-counts.
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| 238 |
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| 239 | -i --file-info
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| 240 | Print information about the profile files that
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| 241 | are read. The information consists of the
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| 242 | number and types of records present in the
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| 243 | profile file. Currently, a profile file can
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| 244 | contain any number and any combination of histogram,
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| 245 | call-graph, or basic-block count records.
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| 246 |
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| 247 | -s --sum
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| 248 |
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| 249 | -x --all-lines
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| 250 | This option affects annotated source output only.
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| 251 | By default, only the lines at the beginning of
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| 252 | a basic-block are annotated. If this option is
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| 253 | specified, every line in a basic-block is annotated
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| 254 | by repeating the annotation for the first line.
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| 255 | This option is identical to tcov's "-a".
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| 256 |
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| 257 | -I dirs --directory-path=dirs
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| 258 | This option affects annotated source output only.
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| 259 | Specifies the list of directories to be searched
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| 260 | for source files. The argument "dirs" is a colon
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| 261 | separated list of directories. By default, gprof
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| 262 | searches for source files relative to the current
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| 263 | working directory only.
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| 264 |
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| 265 | -z --display-unused-functions
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| 266 |
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| 267 | -m num --min-count=num
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| 268 | This option affects annotated source and execution
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| 269 | count output only. Symbols that are executed
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| 270 | less than "num" times are suppressed. For annotated
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| 271 | source output, suppressed symbols are marked
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| 272 | by five hash-marks (#####). In an execution count
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| 273 | output, suppressed symbols do not appear at all.
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| 274 |
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| 275 | -L --print-path
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| 276 | Normally, source filenames are printed with the path
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| 277 | component suppressed. With this option, gprof
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| 278 | can be forced to print the full pathname of
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| 279 | source filenames. The full pathname is determined
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| 280 | from symbolic debugging information in the image file
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| 281 | and is relative to the directory in which the compiler
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| 282 | was invoked.
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| 283 |
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| 284 | -y --separate-files
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| 285 | This option affects annotated source output only.
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| 286 | Normally, gprof prints annotated source files
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| 287 | to standard-output. If this option is specified,
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| 288 | annotated source for a file named "path/filename"
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| 289 | is generated in the file "filename-ann". That is,
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| 290 | annotated output is {\em always\/} generated in
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| 291 | gprof's current working directory. Care has to
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| 292 | be taken if a program consists of files that have
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| 293 | identical filenames, but distinct paths.
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| 294 |
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| 295 | -c --static-call-graph
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| 296 |
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| 297 | -t num --table-length=num
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| 298 | This option affects annotated source output only.
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| 299 | After annotating a source file, gprof generates
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| 300 | an execution count summary consisting of a table
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| 301 | of lines with the top execution counts. By
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| 302 | default, this table is ten entries long.
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| 303 | This option can be used to change the table length
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| 304 | or, by specifying an argument value of 0, it can be
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| 305 | suppressed completely.
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| 306 |
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| 307 | -n symspec --time=symspec
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| 308 | Only symbols selected by "symspec" are considered
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| 309 | in total and percentage time computations.
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| 310 | However, this option does not affect percentage time
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| 311 | computation for the flat profile.
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| 312 | If the option is specified multiple times, the union
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| 313 | of all selected symbols is used in time computations.
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| 314 |
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| 315 | -N --no-time=symspec
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| 316 | Exclude the symbols selected by "symspec" from
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| 317 | total and percentage time computations.
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| 318 | However, this option does not affect percentage time
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| 319 | computation for the flat profile.
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| 320 | This option is ignored if any --time options are
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| 321 | specified.
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| 322 |
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| 323 | -w num --width=num
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| 324 | Sets the output line width. Currently, this option
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| 325 | affects the printing of the call-graph function index
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| 326 | only.
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| 327 |
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| 328 | -e <no long form---for backwards compatibility only>
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| 329 | -E <no long form---for backwards compatibility only>
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| 330 | -f <no long form---for backwards compatibility only>
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| 331 | -F <no long form---for backwards compatibility only>
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| 332 | -k <no long form---for backwards compatibility only>
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| 333 | -b --brief
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| 334 | -dnum --debug[=num]
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| 335 |
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| 336 | -h --help
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| 337 | Prints a usage message.
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| 338 |
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| 339 | -O name --file-format=name
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| 340 | Selects the format of the profile data files.
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| 341 | Recognized formats are "auto", "bsd", "magic",
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| 342 | and "prof". The last one is not yet supported.
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| 343 | Format "auto" attempts to detect the file format
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| 344 | automatically (this is the default behavior).
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| 345 | It attempts to read the profile data files as
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| 346 | "magic" files and if this fails, falls back to
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| 347 | the "bsd" format. "bsd" forces gprof to read
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| 348 | the data files in the BSD format. "magic" forces
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| 349 | gprof to read the data files in the "magic" format.
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| 350 |
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| 351 | -T --traditional
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| 352 | -v --version
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| 353 |
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| 354 | ** File Format Changes
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| 355 |
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| 356 | The old BSD-derived format used for profile data does not contain a
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| 357 | magic cookie that allows to check whether a data file really is a
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| 358 | gprof file. Furthermore, it does not provide a version number, thus
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| 359 | rendering changes to the file format almost impossible. GNU gprof
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| 360 | uses a new file format that provides these features. For backward
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| 361 | compatibility, GNU gprof continues to support the old BSD-derived
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| 362 | format, but not all features are supported with it. For example,
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| 363 | basic-block execution counts cannot be accommodated by the old file
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| 364 | format.
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| 365 |
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| 366 | The new file format is defined in header file \file{gmon_out.h}. It
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| 367 | consists of a header containing the magic cookie and a version number,
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| 368 | as well as some spare bytes available for future extensions. All data
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| 369 | in a profile data file is in the native format of the host on which
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| 370 | the profile was collected. GNU gprof adapts automatically to the
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| 371 | byte-order in use.
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| 372 |
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| 373 | In the new file format, the header is followed by a sequence of
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| 374 | records. Currently, there are three different record types: histogram
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| 375 | records, call-graph arc records, and basic-block execution count
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| 376 | records. Each file can contain any number of each record type. When
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| 377 | reading a file, GNU gprof will ensure records of the same type are
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| 378 | compatible with each other and compute the union of all records. For
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| 379 | example, for basic-block execution counts, the union is simply the sum
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| 380 | of all execution counts for each basic-block.
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| 381 |
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| 382 | *** Histogram Records
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| 383 |
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| 384 | Histogram records consist of a header that is followed by an array of
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| 385 | bins. The header contains the text-segment range that the histogram
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| 386 | spans, the size of the histogram in bytes (unlike in the old BSD
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| 387 | format, this does not include the size of the header), the rate of the
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| 388 | profiling clock, and the physical dimension that the bin counts
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| 389 | represent after being scaled by the profiling clock rate. The
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| 390 | physical dimension is specified in two parts: a long name of up to 15
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| 391 | characters and a single character abbreviation. For example, a
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| 392 | histogram representing real-time would specify the long name as
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| 393 | "seconds" and the abbreviation as "s". This feature is useful for
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| 394 | architectures that support performance monitor hardware (which,
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| 395 | fortunately, is becoming increasingly common). For example, under DEC
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| 396 | OSF/1, the "uprofile" command can be used to produce a histogram of,
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| 397 | say, instruction cache misses. In this case, the dimension in the
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| 398 | histogram header could be set to "i-cache misses" and the abbreviation
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| 399 | could be set to "1" (because it is simply a count, not a physical
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| 400 | dimension). Also, the profiling rate would have to be set to 1 in
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| 401 | this case.
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| 402 |
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| 403 | Histogram bins are 16-bit numbers and each bin represent an equal
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| 404 | amount of text-space. For example, if the text-segment is one
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| 405 | thousand bytes long and if there are ten bins in the histogram, each
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| 406 | bin represents one hundred bytes.
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| 407 |
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| 408 |
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| 409 | *** Call-Graph Records
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| 410 |
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| 411 | Call-graph records have a format that is identical to the one used in
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| 412 | the BSD-derived file format. It consists of an arc in the call graph
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| 413 | and a count indicating the number of times the arc was traversed
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| 414 | during program execution. Arcs are specified by a pair of addresses:
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| 415 | the first must be within caller's function and the second must be
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| 416 | within the callee's function. When performing profiling at the
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| 417 | function level, these addresses can point anywhere within the
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| 418 | respective function. However, when profiling at the line-level, it is
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| 419 | better if the addresses are as close to the call-site/entry-point as
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| 420 | possible. This will ensure that the line-level call-graph is able to
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| 421 | identify exactly which line of source code performed calls to a
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| 422 | function.
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| 423 |
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| 424 | *** Basic-Block Execution Count Records
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| 425 |
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| 426 | Basic-block execution count records consist of a header followed by a
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| 427 | sequence of address/count pairs. The header simply specifies the
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| 428 | length of the sequence. In an address/count pair, the address
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| 429 | identifies a basic-block and the count specifies the number of times
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| 430 | that basic-block was executed. Any address within the basic-address can
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| 431 | be used.
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| 432 |
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| 433 | IMPLEMENTATION NOTE: gcc -a can be used to instrument a program to
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| 434 | record basic-block execution counts. However, the __bb_exit_func()
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| 435 | that is currently present in libgcc2.c does not generate a gmon.out
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| 436 | file in a suiteable format. This should be fixed for future releases
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| 437 | of gcc. In the meantime, contact davidm@cs.arizona.edu for a version
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| 438 | of __bb_exit_func() to is appropriate.
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