[PATCH] D71312: [InstCombine] Fold X / abs(X) to X < 0 ? -1 : 1

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 added a comment.

In D71312#1778626 <https://reviews.llvm.org/D71312#1778626>, @craig.topper wrote:

> Isn't it sufficient to just check that the true/false values of the select are x and -x. The condition itself doesn't matter.   x / (select c, x, -x) ->  select c ? 1 : -1




  Name: div abs
  %cmp = icmp slt i32 %x, 0
  %sub = sub nsw i32 0, %x
  %cond = select i1 %cmp, i32 %sub, i32 %x
  %div = sdiv i32 %x, %cond
  =>
  %div = select i1 %cmp, i32 -1, i32 1

Right.


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https://reviews.llvm.org/D71312