[PATCH] D48754: [InstCombine] canonicalize abs pattern

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

Actually, it will fail even without the extra use, so this is a minimal test:

  define i32 @abs_canonical_9(i32 %a, i32 %b) {
    %tmp2 = sub i32 %b, %a
    %tmp1 = sub i32 %a, %b
    %cmp = icmp sgt i32 %tmp1, -1
    %abs = select i1 %cmp, i32 %tmp1, i32 %tmp2
    ret i32 %abs
  }

We can not just replace operands without considering the order of the instructions. It would be better to create a new instruction with the IRBuilder, so we don't have to worry about this problem.


https://reviews.llvm.org/D48754