[PATCH] D11866: transform fmin/fmax calls when possible (PR24314)

[Sanjay Patel via llvm-commits]

spatel added a comment.

"rewriting an fmax() implementation in IR"

For reference, I think that would look like this:

  define double @fmax(double %x, double %y) {
  entry:
    %cmp0 = fcmp uno double %x, %x
    br i1 %cmp0, label %return, label %if.1
  
  if.1:
    %cmp1 = fcmp uno double %y, %y
    br i1 %cmp1, label %return, label %if.2
  
  if.2:
    %cmp2 = fcmp ogt double %x, %y
    %max = select i1 %cmp2, double %x, double %y
    br label %return
  
  return:
    %retval = phi double [ %y, %entry ], [ %x, %if.1 ], [ %max, %if.2 ]
    ret double %retval
  }

This is based on the C reference code from:
http://www.opensource.apple.com/source/Libm/Libm-315/Source/PowerPC/minmaxdim.c


http://reviews.llvm.org/D11866