[turbofan] Add a Simplified::CheckMaps instruction.

src/compiler/verifier.cc

Index: src/compiler/verifier.cc
diff --git a/src/compiler/verifier.cc b/src/compiler/verifier.cc
index a0f68b09cf2f98bb7366126e0ee98ac65caa1442..31472ead737f4c62145a58717be4f7702280bb60 100644
--- a/src/compiler/verifier.cc
+++ b/src/compiler/verifier.cc
@@ -309,7 +309,7 @@ void Verifier::Visitor::Check(Node* node) {
       CHECK_EQ(IrOpcode::kStart,
                NodeProperties::GetValueInput(node, 0)->opcode());
       // Parameter has an input that produces enough values.
-      int index = OpParameter<int>(node);
+      int index = ParameterIndexOf(node->op());
       Node* input = NodeProperties::GetValueInput(node, 0);
       // Currently, parameter indices start at -1 instead of 0.
       CHECK_GT(input->op()->ValueOutputCount(), index + 1);
@@ -718,6 +718,15 @@ void Verifier::Visitor::Check(Node* node) {
       // CheckUpperIs(node, to));
       break;
     }
+    case IrOpcode::kCheckMaps: {
+      // CheckMaps only produces control.
+      CheckNotTyped(node);
+      int32_t map_count = OpParameter<int32_t>(node);
+      // expect [obj, map*, framestate, effect, control]
+      CHECK_EQ(map_count + 4, node->InputCount());
+      CHECK_EQ(IrOpcode::kFrameState, node->InputAt(1 + map_count)->opcode());
+      break;
+    }
 
     case IrOpcode::kLoadField:
       // Object -> fieldtype