>>>>> On Tue, 18 Oct 2022, Mike Gilbert wrote: > Reference: https://gcc.gnu.org/wiki/x87note
Which says: | ... the amount of worst-case error that could possibly happen using | the x87 (with any amount of intermediate rounding) is at worst the | same as true 64 or 32 bit arithmetic, and in practice is almost always | better. and: | Note, however, that this greater repeatability comes at the cost of | lost precision (i.e. SSE always gets the same precision because it | always takes the equivalent of the x87's worst case: a forced round | down at each step). So, it comes with a price, and I wonder if we shouldn't leave that choice to the user, and go with the upstream GCC default? > -CFLAGS_x86="-m32" > +CFLAGS_x86="-m32 -mfpmath=sse" Also, why add the flag only to CFLAGS_x86 but not to CFLAGS_amd64? They should have the same single and double precision arithmetic? Ulrich
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