How to apply gprof on gcc?

[Chunhua Liao]

Hi,
I'd like to see the hotspots in gcc using gprof. Does anybody has similar
experience ?
Here is my unsuccessful attempt:

Build gcc 3.5 2004-8-10 with:
 make BOOT_CFLAGS='-pg -O0' bootstrap
but it failed.

    However, there were some gmon.out scattered in the build directories
after that,  I tried gprof cc1 gmon.out in the builddir/gcc and found the
call graph was very incomplete. Only a few out of over 6000 functions were
shown.

Best Regards
Liao