Better support for 'polymorphic' JS and external arrays

src/x64/macro-assembler-x64.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 1878 matching lines @@
                               Label* fail,
                               bool is_heap_object) {
   if (!is_heap_object) {
     JumpIfSmi(obj, fail);
   }
   Cmp(FieldOperand(obj, HeapObject::kMapOffset), map);
   j(not_equal, fail);
 }
 
 
+void MacroAssembler::CheckMaps(Register obj,
+                               ZoneMapList* receiver_maps,
+                               Label* fail,
+                               bool is_heap_object) {
+  if (!is_heap_object) {
+    testb(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), receiver_maps->at(0));
+    j(not_equal, fail);
+  } else {
+    NearLabel map_match;
+    for (int current = 0; current < receiver_maps->length() - 1; ++current) {
+      Handle<Map> current_map = receiver_maps->at(current);
+      Cmp(FieldOperand(obj, HeapObject::kMapOffset), current_map);
+      j(equal, &map_match);
+    }
+    Cmp(FieldOperand(obj, HeapObject::kMapOffset),
+        receiver_maps->at(receiver_maps->length()-1));
+    j(not_equal, fail);
+    bind(&map_match);
+  }
+}
+
+
 void MacroAssembler::AbortIfNotNumber(Register object) {
   NearLabel ok;
   Condition is_smi = CheckSmi(object);
   j(is_smi, &ok);
   Cmp(FieldOperand(object, HeapObject::kMapOffset),
       isolate()->factory()->heap_number_map());
   Assert(equal, "Operand not a number");
   bind(&ok);
 }
 
@@ skipping 1001 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // 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_X64