no_instrument_function attribute ignored by -Os

[Groleo Marius]

Hi,

I tried using -finstrument-functions and -Os flags at the same time but
the compiled test program segfaults due to recursive calls:

$> gcc -g -Os -finstrument-functions ptrace.c && ./a.out
Segmentation fault (core dumped)
$> gdb a.out core
#0  0x080485b7 in __cyg_profile_func_enter (this_fn=0x80485a2,
call_site=0x80485bc) at ptrace.c:15
#1  0x080485bc in __cyg_profile_func_enter (this_fn=0x80485a2,
call_site=0x80485bc) at ptrace.c:15
#2  0x080485bc in __cyg_profile_func_enter (this_fn=0x80485a2,
call_site=0x80485bc) at ptrace.c:15
#3  0x080485bc in __cyg_profile_func_enter (this_fn=0x80485a2,
call_site=0x80485bc) at ptrace.c:15
#4  0x080485bc in __cyg_profile_func_enter (this_fn=0x80485a2,
call_site=0x80485bc) at ptrace.c:15

I disabled function instrumentation for __cyg_profile_func_enter using
 __attribute__ ((no_instrument_function))
but it looks like it's ignored.

Does -Os behavior specifically ignores  the 'no_instrument_function' attribute ?

Taking -Os out makes it work:
$> gcc -g -finstrument-functions ptrace.c && ./a.out
enter 0x8048552
enter 0x804851f
enter 0x80484ec
enter 0x80484be
exit 0x80484be
exit 0x80484ec
exit 0x804851f
enter 0x80484be
exit 0x80484be
exit 0x8048552


-- 
Regards!
http://groleo.wordpress.com/

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>

#ifdef __cplusplus
extern "C" {
#endif

/* called upon function entry */
void
__attribute__ ((no_instrument_function))
__cyg_profile_func_enter(void *this_fn, void *call_site)
{
	fprintf(stdout, "enter %p\n", this_fn);
}

/* called upon function exit */
void
__attribute__ ((no_instrument_function))
__cyg_profile_func_exit(void *this_fn, void *call_site)
{
	fprintf(stdout, "exit %p\n", this_fn);
}
void func_c( void )
{
	return;
}

void func_b( void )
{
	func_c();
}

void func_a( void )
{
	func_b();
}

#ifdef __cplusplus
}
#endif

int main()
{
	func_a();
	func_c();
}