We should catch problems like JDK-8257166 during CCP by adding some verification code:

@@ -1717,11 +1717,13 @@ void PhaseCCP::analyze() {
   // Push root onto worklist
   Unique_Node_List worklist;
   worklist.push(C->root());
+  DEBUG_ONLY(Unique_Node_List worklist_verify;)
 
   // Pull from worklist; compute new value; push changes out.
   // This loop is the meat of CCP.
   while( worklist.size() ) {
     Node *n = worklist.pop();
+    DEBUG_ONLY(worklist_verify.push(n);)
     const Type *t = n->Value(this);
     if (t != type(n)) {
       assert(ccp_type_widens(t, type(n)), "ccp type must widen");
@@ -1813,6 +1815,21 @@ void PhaseCCP::analyze() {
       }
     }
   }
+#ifdef ASSERT
+  while (worklist_verify.size()) {
+    Node* n = worklist_verify.pop();
+    const Type* told = type(n);
+    const Type* tnew = n->Value(this);
+    if (told != tnew) {
+      told->dump_on(tty);
+      tty->print_cr("");
+      tnew->dump_on(tty);
+      tty->print_cr("");
+      n->dump(1);
+      fatal("missed optimization opportunity");
+    }
+  }
+#endif
 }