search for: vfmadd132ss

Hi Tim, Thanks for the thorough explanation. It makes perfect sense. I was not aware fast-math is supposed to prevent more precision being used than what is in the standard. I came across this issue while looking into the output or different compilers. XL and Microsoft compiler seem to have that turned on by default. But I assume that clang follows what gcc does, and have that turned off.

...gt; > $ cat fma.c > float foo(float x, float y, float z) { return x * y + z; } > > $ ./clang -march=core-avx2 -O2 -S fma.c -o - | grep ss >     vmulss    %xmm1, %xmm0, %xmm0 >     vaddss    %xmm2, %xmm0, %xmm0 > > $ ./gcc -march=core-avx2 -O2 -S fma.c -o - | grep ss >     vfmadd132ss    %xmm1, %xmm2, %xmm0 > > ---------------------------------------------------------------------- > This was brought up in Dec 2013 on this list: > http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-December/068868.html > > I don't see an answer as to whether this is a bug for a...