------- Comment #3 from uros at kss-loka dot si 2006-10-04 06:46 -------
> I'm afraid you're missing my point. > The problem is that for 64-bit and 32-bit floating-point to integer > conversion, > x86 (32bit) target uses fistp* whereas x86_64 (64-bit) target uses cvt* WHEN > -mfpmath=387. > This defeats the purpose of the option -mfpmath=387 which is supposed to make > floating-point computations to use 387, instead of SSE2. If SSE is available, then SSE cvt* is used in order to avoid long control-word setting sequences. This is cheaper even if we have to move value from x87 register, as cvt* can handle mem->reg transformations. If you really need fistp* sequence, you can try with -mno-sse2 (you can't just disable sse on x86_64 target) or perhaps use -msse3, where fisttp insn will be generated. Saying that, I wonder where excess precision effects come into play here. We are talking about truncate-to-integer instruction, so I would really like to see an example of this effect. > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29337
