[llvm] [LV] Rewrite UDiv A, B -> UDiv A, UMax(B, 1) in trip counts if needed. (PR #92177)

[Florian Hahn via llvm-commits]

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@@ -4304,12 +4304,22 @@ ScalarEvolution::getSequentialMinMaxExpr(SCEVTypes Kind,
   }
 
   for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
+    bool MayBeUB = SCEVExprContains(Ops[i], [this](const SCEV *S) {
+      auto *UDiv = dyn_cast<SCEVUDivExpr>(S);
+      // The UDiv may be UB if the divisor is poison or zero. Unless the divisor
+      // is a non-zero constant, we have to assume the UDiv may be UB.
+      return UDiv && (!isa<SCEVConstant>(UDiv->getOperand(1)) ||
+                      !isKnownNonZero(UDiv->getOperand(1)));
+    });
+
+    if (MayBeUB)
+      continue;
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fhahn wrote:

Added thanks!

https://github.com/llvm/llvm-project/pull/92177