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-Ofast doesn't license any transforms that can break GEMM. Everything that it licenses is already used universally by GEMM kernels, because those transforms hav
by stephencanon 5y ago
-Ofast doesn't license any transforms that can break GEMM. Everything that it licenses is already used universally by GEMM kernels, because those transforms have no effect on the standard backwards stability bounds for matrix multiplication.
- gnufx 5y agoIndeed, the BLIS test suite with generic C kernels passes, not just level 3, though only the -funsafe-math-optimizations of -ffast-math is used by default. (I don't know the specifics for OpenBLAS, but it must be similar.) At least some of BLAS was defined before there even was an IEEE floating point standard.