Optimizing redundant load away

[Tilmann Scheller]

Hi,

quick question: I want to implement the transformation below and I'm wondering where in the middle-end this kind of transformation would fit in, any suggestions?

All instructions are in the same basic block:

  %arrayidx = getelementptr inbounds [128 x float]* @heap, i32 0, i32 %ito
  %a0 = load float* %arrayidx, align 4, !tbaa !3

  %add = add i32 %ito, 1
  %arrayidx1 = getelementptr inbounds [128 x float]* @heap, i32 0, i32 %add
  %a1 = load float* %arrayidx1, align 4, !tbaa !3

; Use of %a0 and %a1 and no stores which would invalidate %a0 or %a1
...

; Do the following transformation (e.g. kill the redundant load):
  %ito.addr.0 = select i1 %cmp, i32 %add, i32 %ito
  %arrayidx2 = getelementptr inbounds [128 x float]* @heap, i32 0, i32 %ito.addr.0
  %a2 = load float* %arrayidx2, align 4, !tbaa !3
-->
  %a2 = select i1 %cmp, float %a1, float %a0

; Use of %a2
...

Thanks!

Regards,

Tilmann