[llvm] [SCEV] Introduce exact flag for UDiv (PR #225065)

[David Sherwood via llvm-commits]

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@@ -346,8 +346,12 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
       BO->setHasNoUnsignedWrap();
     if (IsNSW)
       BO->setHasNoSignedWrap();
+    if (IsExact)
+      BO->setIsExact();
     return Builder.Insert(BO);
   }
+  if (IsExact)
+    return Builder.CreateExactBinOp(Opcode, LHS, RHS, IsExact);
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david-arm wrote:

Are the `exact` and `nsw`/`nuw` flags mutually exclusive here? If so, is it worth asserting somewhere during the creation of SCEV nodes that we never set `exact` in combination with other flags?

https://github.com/llvm/llvm-project/pull/225065