Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6607,22 +6607,29 @@
   return nullptr;
 }
 
+/// Fills \p Ops with unique operands of \p S, if it has operands. If not,
+/// \p Ops remains unmodified.
+static void collectUniqueOps(const SCEV *S,
+                             SmallPtrSetImpl<const SCEV *> &Ops) {
+  if (auto *S2 = dyn_cast<SCEVCastExpr>(S))
+    for (auto *Op : S2->operands())
+      Ops.insert(Op);
+  else if (auto *S2 = dyn_cast<SCEVNAryExpr>(S))
+    for (auto *Op : S2->operands())
+      Ops.insert(Op);
+  else if (auto *S2 = dyn_cast<SCEVUDivExpr>(S))
+    for (auto *Op : S2->operands())
+      Ops.insert(Op);
+}
+
 const Instruction *
 ScalarEvolution::getDefiningScopeBound(ArrayRef<const SCEV *> Ops) {
   // Do a bounded search of the def relation of the requested SCEVs.
-  SmallSet<const SCEV *, 16> Visited;
+  SmallPtrSet<const SCEV *, 16> Visited;
   SmallVector<const SCEV *> Worklist;
-  auto pushOp = [&](const SCEV *S) {
-    if (!Visited.insert(S).second)
-      return;
-    // Threshold of 30 here is arbitrary.
-    if (Visited.size() > 30)
-      return;
-    Worklist.push_back(S);
-  };
-
   for (auto *S : Ops)
-    pushOp(S);
+    if (Visited.insert(S).second)
+      Worklist.push_back(S);
 
   const Instruction *Bound = nullptr;
   while (!Worklist.empty()) {
@@ -6630,15 +6637,14 @@
     if (auto *DefI = getNonTrivialDefiningScopeBound(S)) {
       if (!Bound || DT.dominates(Bound, DefI))
         Bound = DefI;
-    } else if (auto *S2 = dyn_cast<SCEVCastExpr>(S))
-      for (auto *Op : S2->operands())
-        pushOp(Op);
-    else if (auto *S2 = dyn_cast<SCEVNAryExpr>(S))
-      for (auto *Op : S2->operands())
-        pushOp(Op);
-    else if (auto *S2 = dyn_cast<SCEVUDivExpr>(S))
-      for (auto *Op : S2->operands())
-        pushOp(Op);
+    } else {
+      SmallPtrSet<const SCEV *, 4> Ops;
+      collectUniqueOps(S, Ops);
+      for (auto *Op : Ops)
+        // Threshold of 30 here is arbitrary.
+        if (Visited.size() <= 30 && Visited.insert(Op).second)
+          Worklist.push_back(Op);
+    }
   }
   return Bound ? Bound : &*F.getEntryBlock().begin();
 }
@@ -12915,14 +12921,7 @@
   // Verify intergity of SCEV users.
   for (const auto &S : UniqueSCEVs) {
     SmallPtrSet<const SCEV *, 4> Ops;
-    if (const auto *NS = dyn_cast<SCEVNAryExpr>(&S))
-      Ops.insert(NS->op_begin(), NS->op_end());
-    else if (const auto *CS = dyn_cast<SCEVCastExpr>(&S))
-      Ops.insert(CS->getOperand());
-    else if (const auto *DS = dyn_cast<SCEVUDivExpr>(&S)) {
-      Ops.insert(DS->getLHS());
-      Ops.insert(DS->getRHS());
-    }
+    collectUniqueOps(&S, Ops);
     for (const auto *Op : Ops) {
       // We do not store dependencies of constants.
       if (isa<SCEVConstant>(Op))