[Bug middle-end/105905] A possible rounding error

pinskia at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Sun Jun 12 01:24:25 GMT 2022


Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
         Resolution|---                         |INVALID
             Status|WAITING                     |RESOLVED

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So clang defaults to -ffp-contract=off (maybe on which is actually the same as
off for GCC) while GCC defaults to -ffp-contract=fast. And with -march=native,
the FMA instruction is enabled which allows GCC to do contractions for some
floating point and uses FMA more.

Using -ffp-contract=off (or -ffp-contract=on) will get the behavior the
developer wants.

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