Thread

1. khuey · 1789736380 · focus · HN ↗

   If you don't _need_ subnormals MXCSR.DAZ/FTZ (which you can get gcc to set via -mdaz-ftz) will let you ignore all of this.

   1. bee_rider · 1789738030 · focus · HN ↗

      IIRC intel’s compilers enable FTZ/DAZ, at least at higher optimization levels.

      1. account42 · 1789739823 · focus · HN ↗

         GCC does with the infamous -ffast-math as well.

         1. gpderetta · 1789743925 · focus · HN ↗

            IIRC that has been since split out of the flag and need to be asked for separately at link time.

            1. jcranmer · 1789744500 · focus · HN ↗

               If you use -ffast-math when linking an executable but not a shared library, both gcc and clang will link in crtfastmath.o which has the bit of code to set the DAZ/FTZ flags.

               1. gpderetta · 1789768601 · focus · HN ↗

                  right, but the issue was that if an application was linked with a library that happened to link with a fast-math shared library, it would unknowingly bring along the crt code. Now the only way to get it is to use the fast-math flag when linking the final binary, which at least is an explicit request.

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