Better support for 'polymorphic' JS and external arrays

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index ad567bca3d3981fd7f5292f202555558a929ea14..16a2c789c637176903a43136e5538ebff8428f01 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -203,6 +203,37 @@ void MacroAssembler::CheckMap(Register obj,
 }
 
 
+void MacroAssembler::CheckMaps(Register obj,
+                               ZoneMapList* receiver_maps,
+                               Label* fail,
+                               bool is_heap_object) {
+  if (!is_heap_object) {
+    test(obj, Immediate(kSmiTagMask));
+    j(zero, fail);
+  }
+
+  // Check that the map matches.
+  if (receiver_maps->length() == 0) {
+    jmp(fail);
+  } else if (receiver_maps->length() == 1) {
+    cmp(FieldOperand(obj, HeapObject::kMapOffset),
+        Immediate(Handle<Map>(receiver_maps->at(0))));
+    j(not_equal, fail, not_taken);
+  } else {
+    NearLabel map_match;
+    for (int current = 0; current < receiver_maps->length() - 1; ++current) {
+      cmp(FieldOperand(obj, HeapObject::kMapOffset),
+          Immediate(Handle<Map>(receiver_maps->at(current))));
+      j(equal, &map_match, not_taken);
+    }
+    cmp(FieldOperand(obj, HeapObject::kMapOffset),
+        Immediate(Handle<Map>(receiver_maps->at(receiver_maps->length()-1))));
+    j(not_equal, fail, not_taken);
+    bind(&map_match);
+  }
+}
+
+
 Condition MacroAssembler::IsObjectStringType(Register heap_object,
                                              Register map,
                                              Register instance_type) {