[llvm] [InstCombine] Simplify `(X / C0) * C1 + (X % C0) * C2` to `(X / C0) * (C1 - C2 * C0) + X * C2` (PR #76285)

[Yingwei Zheng via llvm-commits]

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@@ -3872,6 +3872,10 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
     }
   }
 
+  if (cast<PossiblyDisjointInst>(I).isDisjoint())
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dtcxzyw wrote:

It is ugly. But I don't know the best approach to treat `or disjoint` as `add nsw nuw`.

It is a phase ordering issue. We cannot assume that `ReassociatePass` will revert the canonicalization `add -> or disjoint`. BTW, I see this change achieves higher coverage in my benchmark (in `openexr/ImfTimeCode.cpp` and `z3/mpf.cpp`).


https://github.com/llvm/llvm-project/pull/76285