[turbofan] Track multiple maps for LoadElimination.

src/compiler/js-builtin-reducer.cc

Index: src/compiler/js-builtin-reducer.cc
diff --git a/src/compiler/js-builtin-reducer.cc b/src/compiler/js-builtin-reducer.cc
index 762020438878fdbc5566ba07848fd601c870b6ca..b4db6fe2b0696f8e5f10fd3e4f1f959f345064c7 100644
--- a/src/compiler/js-builtin-reducer.cc
+++ b/src/compiler/js-builtin-reducer.cc
@@ -113,11 +113,10 @@ MaybeHandle<Map> GetMapWitness(Node* node) {
   for (Node* dominator = effect;;) {
     if (dominator->opcode() == IrOpcode::kCheckMaps &&
         dominator->InputAt(0) == receiver) {
-      if (dominator->op()->ValueInputCount() == 2) {
-        HeapObjectMatcher m(dominator->InputAt(1));
-        if (m.HasValue()) return Handle<Map>::cast(m.Value());
-      }
-      return MaybeHandle<Map>();
+      ZoneHandleSet<Map> const& maps =
+          CheckMapsParametersOf(dominator->op()).maps();
+      return (maps.size() == 1) ? MaybeHandle<Map>(maps[0])
+                                : MaybeHandle<Map>();
     }
     if (dominator->op()->EffectInputCount() != 1) {
       // Didn't find any appropriate CheckMaps node.
@@ -326,14 +325,11 @@ bool HasInstanceTypeWitness(Node* receiver, Node* effect,
   for (Node* dominator = effect;;) {
     if (dominator->opcode() == IrOpcode::kCheckMaps &&
         dominator->InputAt(0) == receiver) {
+      ZoneHandleSet<Map> const& maps =
+          CheckMapsParametersOf(dominator->op()).maps();
       // Check if all maps have the given {instance_type}.
-      for (int i = 1; i < dominator->op()->ValueInputCount(); ++i) {
-        Node* const map = NodeProperties::GetValueInput(dominator, i);
-        Type* const map_type = NodeProperties::GetType(map);
-        if (!map_type->IsConstant()) return false;
-        Handle<Map> const map_value =
-            Handle<Map>::cast(map_type->AsConstant()->Value());
-        if (map_value->instance_type() != instance_type) return false;
+      for (size_t i = 0; i < maps.size(); ++i) {
+        if (maps[i]->instance_type() != instance_type) return false;
       }
       return true;
     }