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Nick Clifton 2003-10-29 18:21:10 +00:00
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9
gprof/ChangeLog
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@ -1,3 +1,12 @@
2003-10-29 Nick Clifton <nickc@redhat.com>
* gprof.texi: Apply patch supplied by Eric S Raymond via RMS.
(Compiling): Mention that -pg must be passed to both the compiler
and the linker.
Mention that -a is now deprecated.
(How do I?): Add an entry describing how to get more information
about program hotspots.
2003-10-11 Alan Modra <amodra@bigpond.net.au>
* corefile.c (core_create_function_syms): Don't refer directly to

36
gprof/gprof.texi
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@ -1,6 +1,6 @@
\input texinfo @c -*-texinfo-*-
@setfilename gprof.info
@c Copyright 1988, 1992, 1993, 1998, 1999, 2000, 2001
@c Copyright 1988, 1992, 1993, 1998, 1999, 2000, 2001, 2003
@c Free Software Foundation, Inc.
@settitle GNU gprof
@setchapternewpage odd
@ -19,7 +19,7 @@ END-INFO-DIR-ENTRY
This file documents the gprof profiler of the GNU system.
@c man begin COPYRIGHT
Copyright (C) 1988, 92, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
Copyright (C) 1988, 92, 97, 98, 99, 2000, 2001, 2003 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
@ -53,9 +53,10 @@ This manual describes the @sc{gnu} profiler, @code{gprof}, and how you
can use it to determine which parts of a program are taking most of the
execution time. We assume that you know how to write, compile, and
execute programs. @sc{gnu} @code{gprof} was written by Jay Fenlason.
Eric S. Raymond made some minor corrections and additions in 2003.
@vskip 0pt plus 1filll
Copyright @copyright{} 1988, 92, 97, 98, 99, 2000 Free Software Foundation, Inc.
Copyright @copyright{} 1988, 92, 97, 98, 99, 2000, 2003 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
@ -278,6 +279,14 @@ The @samp{-pg} option also works with a command that both compiles and links:
cc -o myprog myprog.c utils.c -g -pg
@end example
Note: The @samp{-pg} option must be part of your compilation options
as well as your link options. If it is not, when you run @code{gprof}
you will get no profile report and an error message like this:
@example
gprof: gmon.out file is missing call-graph data
@end example
If you run the linker @code{ld} directly instead of through a compiler
such as @code{cc}, you may have to specify a profiling startup file
@file{gcrt0.o} as the first input file instead of the usual startup
@ -307,10 +316,13 @@ instructing the compiler to insert debugging symbols into the program
that match program addresses to source code lines.
@xref{Line-by-line}.
In addition to the @samp{-pg} and @samp{-g} options,
you may also wish to specify the @samp{-a} option when compiling.
This will instrument
the program to perform basic-block counting. As the program runs,
In addition to the @samp{-pg} and @samp{-g} options, older versions of
GCC required you to specify the @samp{-a} option when compiling in
order to instrument it to perform basic-block counting. Newer
versions do not require this option and will not accept it;
basic-block counting is always enabled when @samp{-pg} is on.
When basic-block counting is enabled, as the program runs
it will count how many times it executed each branch of each @samp{if}
statement, each iteration of each @samp{do} loop, etc. This will
enable @code{gprof} to construct an annotated source code
@ -337,7 +349,7 @@ Your program will write the profile data into a file called @file{gmon.out}
just before exiting. If there is already a file called @file{gmon.out},
its contents are overwritten. There is currently no way to tell the
program to write the profile data under a different name, but you can rename
the file afterward if you are concerned that it may be overwritten.
the file afterwards if you are concerned that it may be overwritten.
In order to write the @file{gmon.out} file properly, your program must exit
normally: by returning from @code{main} or by calling @code{exit}. Calling
@ -1627,6 +1639,14 @@ nonce, the estimated figures are usually more useful than misleading.
@chapter Answers to Common Questions
@table @asis
@item How can I get more exact information about hot spots in my program?
Looking at the per-line call counts only tells part of the story.
Because @code{gprof} can only report call times and counts by function,
the best way to get finer-grained information on where the program
is spending its time is to re-factor large functions into sequences
of calls to smaller ones.
@item How do I find which lines in my program were executed the most times?
Compile your program with basic-block counting enabled, run it, then