[contexts] Place the initial JSArray maps on the native context directly.

src/x64/macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 5046 matching lines @@
   }
 }
 
 
 void MacroAssembler::LoadTransitionedArrayMapConditional(
     ElementsKind expected_kind,
     ElementsKind transitioned_kind,
     Register map_in_out,
     Register scratch,
     Label* no_map_match) {
+  DCHECK(IsFastElementsKind(expected_kind));
+  DCHECK(IsFastElementsKind(transitioned_kind));
+
   // Check that the function's map is the same as the expected cached map.
-  LoadNativeContextSlot(Context::JS_ARRAY_MAPS_INDEX, scratch);
-
-  int offset = expected_kind * kPointerSize +
-      FixedArrayBase::kHeaderSize;
-  cmpp(map_in_out, FieldOperand(scratch, offset));
+  movp(scratch, NativeContextOperand());
+  cmpp(map_in_out,
+       ContextOperand(scratch, Context::ArrayMapIndex(expected_kind)));
   j(not_equal, no_map_match);
 
   // Use the transitioned cached map.
-  offset = transitioned_kind * kPointerSize +
-      FixedArrayBase::kHeaderSize;
-  movp(map_in_out, FieldOperand(scratch, offset));
+  movp(map_in_out,
+       ContextOperand(scratch, Context::ArrayMapIndex(transitioned_kind)));
 }
 
 
 #ifdef _WIN64
 static const int kRegisterPassedArguments = 4;
 #else
 static const int kRegisterPassedArguments = 6;
 #endif
 
 
@@ skipping 463 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64