glibc/csu/gmon-start.c

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/* Code to enable profiling at program startup.
Copyright (C) 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <sys/types.h>
#include <sys/gmon.h>
#include <stdlib.h>
#include <unistd.h>
/* Beginning and end of our code segment. */
extern void _start (void), etext (void);
#ifndef HAVE_INITFINI
/* This function gets called at startup by the normal constructor
mechanism. We link this file together with start.o to produce gcrt1.o,
so this constructor will be first in the list. */
void __gmon_start__ (void) __attribute__ ((constructor));
#else
/* In ELF and COFF, we cannot use the normal constructor mechanism to call
__gmon_start__ because gcrt1.o appears before crtbegin.o in the link.
Instead crti.o calls it specially (see initfini.c). */
#endif
void
__gmon_start__ (void)
{
/* Start keeping profiling records. */
monstartup ((u_long) &_start, (u_long) &etext);
/* Call _mcleanup before exitting; it will write out gmon.out from the
collected data. */
atexit (&_mcleanup);
}