[cfe-dev] [llvm-dev] RFC: change -fp-contract=off to actually disable FMAs
Stephen Canon via cfe-dev
cfe-dev at lists.llvm.org
Fri Jul 12 10:30:42 PDT 2019
> On Jul 12, 2019, at 12:55 PM, Matt Arsenault <arsenm2 at gmail.com> wrote:
> Yes. FMAD is supposed to give the same result as the separate FMUL and FADD with the intermediate rounding step. It exists because most of the combines for FMA still apply, and AMDGPU has an instruction that does this (as long as denormal flushing is OK). I don’t know of any other users.
armv7 also has a non-fused floating-point multiply-add (VMLA as opposed to the fused operation VFMA).
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