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 2583 matching lines @@
   movq(temp_xmm_reg, temp_reg);
   addsd(temp_xmm_reg, input_reg);
   cvttsd2si(result_reg, temp_xmm_reg);
   testl(result_reg, Immediate(0xFFFFFF00));
   j(zero, &done, Label::kNear);
   Set(result_reg, 255);
   bind(&done);
 }
 
 
+void MacroAssembler::DispatchMap(Register obj,
+                                 Handle<Map> map,
+                                 Handle<Code> success,
+                                 SmiCheckType smi_check_type) {
+  Label fail;
+  if (smi_check_type == DO_SMI_CHECK) {
+    JumpIfSmi(obj, &fail);
+  }
+  Cmp(FieldOperand(obj, HeapObject::kMapOffset), map);
+  j(equal, success, RelocInfo::CODE_TARGET);
+
+  bind(&fail);
+}
+
+
 void MacroAssembler::AbortIfNotNumber(Register object) {
   Label ok;
   Condition is_smi = CheckSmi(object);
   j(is_smi, &ok, Label::kNear);
   Cmp(FieldOperand(object, HeapObject::kMapOffset),
       isolate()->factory()->heap_number_map());
   Assert(equal, "Operand not a number");
   bind(&ok);
 }
 
@@ skipping 1070 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