Revert "Refactor FirstObject logic"

This reverts commit f160e9c.

Author: nikic

llvm/lib/Analysis/ValueTracking.cpp

@@ -6615,18 +6615,19 @@ const Value *llvm::getUnderlyingObjectAggressive(const Value *V) {
   SmallPtrSet<const Value *, 8> Visited;
   SmallVector<const Value *, 8> Worklist;
   Worklist.push_back(V);
-  const Value *Object = nullptr;
+  const Value *Object = nullptr, *FirstObject = nullptr;
   do {
     const Value *P = Worklist.pop_back_val();
     P = getUnderlyingObject(P);
 
+    if (!FirstObject)
+      FirstObject = P;
+
     if (!Visited.insert(P).second)
       continue;
 
-    if (Visited.size() == MaxVisited) {
-      Object = nullptr;
-      break;
-    }
+    if (Visited.size() == MaxVisited)
+      return FirstObject;
 
     if (auto *SI = dyn_cast<SelectInst>(P)) {
       Worklist.push_back(SI->getTrueValue());
@@ -6641,16 +6642,10 @@ const Value *llvm::getUnderlyingObjectAggressive(const Value *V) {
 
     if (!Object)
       Object = P;
-    else if (Object != P) {
-      Object = nullptr;
-      break;
-    }
+    else if (Object != P)
+      return FirstObject;
   } while (!Worklist.empty());
 
-  // If we tried looking through phi/select but did not end up with a single
-  // underlying object, fall back to the non-recursive underlying object of V.
-  if (!Object)
-    return getUnderlyingObject(V);
   return Object;
 }