From Bugzilla Helper:
User-Agent: Mozilla/5.0 Galeon/1.2.7 (X11; Linux i686; U;) Gecko/20021203

Description of problem:
A simple function is miscompiled under the following combination of flags: -O
-fPIC -pg

Version-Release number of selected component (if applicable):
gcc-3.2.2-5

How reproducible:
Always

Steps to Reproduce:
1. Create two source files

2. Compile with proper cflags
$ gcc -O2 -fPIC -pg -c bug.c
$ gcc -pg -c bug-main.c
$ gcc -pg bug.o bug-main.o

3. Execute resulting binary
$ ./a.out
Segmentation fault


Actual Results:  Segmentation fault

Expected Results:  Program exits with result code 0

Additional info:
/* bug.c */
/* compile with -pg -fPIC -O2 -> wrong code generated by redhat 9's gcc */
typedef struct { void *(*f)(void *, int); } T;
void *g(T *t) { return t->f(t, 0); }

To actually show the problem, you also need this:
/* bug-main.c */
/* compile with -pg (at least) and use with bug.c */
typedef struct { void *(*f)(void *, int); } T;
void *ff(void* a, int b) { return 0; }
int main(void) { T x = {ff}; g(&x); return 0; }