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 32cbcb21ae75793564c8565d28fdac361c1df0b4..fe52c2b5e763fc4f7993e8adccd2a3bb0095cc4f 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -203,6 +203,22 @@ void MacroAssembler::CheckMap(Register obj,
 }
 
 
+void MacroAssembler::DispatchMap(Register obj,
+                                 Handle<Map> map,
+                                 Handle<Code> success,
+                                 bool is_heap_object) {
+  Label fail;
+  if (!is_heap_object) {
+    test(obj, Immediate(kSmiTagMask));
+    j(zero, &fail);
+  }
+  cmp(FieldOperand(obj, HeapObject::kMapOffset), Immediate(map));
+  j(equal, success, taken);
+
+  bind(&fail);
+}
+
+
 Condition MacroAssembler::IsObjectStringType(Register heap_object,
                                              Register map,
                                              Register instance_type) {