[llvm-dev] FMA canonicalization in IR

Sanjay Patel via llvm-dev llvm-dev at lists.llvm.org
Sat Nov 19 08:26:17 PST 2016

If I have my FMA intrinsics story straight now (thanks for the explanation,
Hal!), I think it raises another question about IR canonicalization (and
may affect the proposed revision to IR FMF):

define float @foo(float %a, float %b, float %c) {
  %mul = fmul fast float %a, %b     ; using 'fast' because there is no
'fma' flag
  %add = fadd fast float %mul, %c
  ret float %add

Should this be:

define float @goo(float %a, float %b, float %c) {
  %maybe.fma = call fast float @llvm.fmuladd.f32(float %a, float %b, float
  ret float %maybe.fma
declare float @llvm.fmuladd.f32(float %a, float %b, float %c)
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