[PATCH] D15294: [x86] inline calls to fmaxf / llvm.maxnum.f32 using maxss (PR24475)

[Zia Ansari via llvm-commits]

zansari added a comment.

Hi Sanjay,

Quick high-level question : wouldn't it be better to pull the intermediate value out of the fmax to reduce the dependence chain?

So, instead of :

cond = isnan(op0)
V = select (op1, op0, cond)
Result = FMAX(op1, V)

do this:

t = FMAX(op1, op0)
cond = isnan(op0)
Result = select (op1, t, cond)

This way, we go from isnan->select->fmax   to   fmax/isnan -> select.


http://reviews.llvm.org/D15294