[llvm] [SCEV] Updates for getUDivExactExpr() to improve handling of MulExpr numerators/denominators (PR #195704)

[Nikita Popov via llvm-commits]

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@@ -3745,6 +3745,39 @@ const SCEV *ScalarEvolution::getUDivExactExpr(SCEVUse LHS, SCEVUse RHS) {
   // just deal with u/exact (multiply, constant). See SCEVDivision towards the
   // end of this file for inspiration.
 
+  if (LHS == RHS)
+    return getConstant(LHS->getType(), 1);
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nikic wrote:

I think all of the logic in this function doesn't actually depend on exactness. Filed https://github.com/llvm/llvm-project/pull/195840 to remove it.

(The code originally handled non-nuw muls, but this was fixed in f1f49c82651af561fdcdab1528a1447da1254ace.)

https://github.com/llvm/llvm-project/pull/195704