Better support for 'polymorphic' JS and external arrays

src/ia32/macro-assembler-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 185 matching lines @@
                               bool is_heap_object) {
   if (!is_heap_object) {
     test(obj, Immediate(kSmiTagMask));
     j(zero, fail);
   }
   cmp(FieldOperand(obj, HeapObject::kMapOffset), Immediate(map));
   j(not_equal, fail);
 }
 
 
+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) {
   mov(map, FieldOperand(heap_object, HeapObject::kMapOffset));
   movzx_b(instance_type, FieldOperand(map, Map::kInstanceTypeOffset));
   ASSERT(kNotStringTag != 0);
   test(instance_type, Immediate(kIsNotStringMask));
   return zero;
 }
 
@@ skipping 1820 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32