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

[David Sherwood via llvm-commits]

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@@ -313,6 +310,13 @@ class SCEVUDivExpr : public SCEV {
 
   ArrayRef<SCEVUse> operands() const { return Operands; }
 
+  void setExactFlag(SCEVFlags Flags) {
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david-arm wrote:

nit: Would be good to add some brief comments here to be consistent with other methods.

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