-O3 ?

[Kyle Sallee]

I tried compiling p7zip with CFLAGS and CXXFLAGS -O3,
yet it segfaulted when ran.
However, when compiling it with -Os it works fine.
I used to expect that problems with optimizations not work
were the fault of a bug in gcc.
But is it?
The problem does not occur when I compile p7zip -O3
and statically link it with glibc instead.
I am almost tempted to try to compile it with -O3 and -g
and run gdb on it.
But is -O3 optimized code debuggable?

For now I will use -Os,
but I wondered if anyone had any information about why -O3
might be problematic with programs linked with uClibc, please.