Hi,
I think this should be part of the same transition, as without it, gcc
will often prefer x87 instructions even if SSE is available, because
that is the cheapest way to be compatible to the 32-bit ABI.
For example:
double square(double num) {
return num * num;
}
without -mfpmath=sse becomes
square(double):
fld QWORD PTR [esp+4]
fmul st, st(0)
ret
even if SSE2 is available, because the return value is expected at the
top of the FP stack. With -mfpmath=sse, it is explicitly loaded there:
square(double):
sub esp, 12
movsd xmm0, QWORD PTR [esp+16]
mulsd xmm0, xmm0
movsd QWORD PTR [esp], xmm0
fld QWORD PTR [esp]
add esp, 12
ret
Simon
