[compiler] Load elimination now traverses CheckTaggedPointer.

src/compiler/load-elimination.cc

Index: src/compiler/load-elimination.cc
diff --git a/src/compiler/load-elimination.cc b/src/compiler/load-elimination.cc
index a451cfce732d18d7a25aaec7234474cbdb57157d..0f9809ea3af895f5001c75bb6b6b13c6eb7310f4 100644
--- a/src/compiler/load-elimination.cc
+++ b/src/compiler/load-elimination.cc
@@ -25,6 +25,19 @@ Reduction LoadElimination::Reduce(Node* node) {
   return NoChange();
 }
 
+namespace {
+
+// If {node} is a CheckTaggedPointer, follow its input until {node} is no
+// longer a CheckTaggedPointer.
+Node* NormalizeCheckTaggedPointer(Node* node) {
+  while (node->opcode() == IrOpcode::kCheckTaggedPointer) {
+    node = NodeProperties::GetValueInput(node, 0);
+  }
+  return node;
+}
+
+}  // namespace
+
 Reduction LoadElimination::ReduceLoadField(Node* node) {
   DCHECK_EQ(IrOpcode::kLoadField, node->opcode());
   FieldAccess const access = FieldAccessOf(node->op());
@@ -44,7 +57,9 @@ Reduction LoadElimination::ReduceLoadField(Node* node) {
       }
       case IrOpcode::kStoreField: {
         if (access == FieldAccessOf(effect->op())) {
-          if (object == NodeProperties::GetValueInput(effect, 0)) {
+          Node* value_input = NormalizeCheckTaggedPointer(
+              NodeProperties::GetValueInput(effect, 0));
+          if (object == value_input) {
             Node* const value = NodeProperties::GetValueInput(effect, 1);
             Type* stored_value_type = NodeProperties::GetType(value);
             Type* load_type = NodeProperties::GetType(node);
@@ -74,7 +89,8 @@ Reduction LoadElimination::ReduceLoadField(Node* node) {
         // These can never interfere with field loads.
         break;
       }
-      case IrOpcode::kFinishRegion: {
+      case IrOpcode::kFinishRegion:
+      case IrOpcode::kCheckTaggedPointer: {
         // "Look through" FinishRegion nodes to make LoadElimination capable
         // of looking into atomic regions.
         if (object == effect) object = NodeProperties::GetValueInput(effect, 0);