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

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 4453 matching lines @@
 }
 
 
 void MacroAssembler::LoadTransitionedArrayMapConditional(
     ElementsKind expected_kind,
     ElementsKind transitioned_kind,
     Register map_in_out,
     Register scratch1,
     Register scratch2,
     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, scratch1);
-  int offset = (expected_kind * kPointerSize) + FixedArrayBase::kHeaderSize;
-  Ldr(scratch2, FieldMemOperand(scratch1, offset));
+  Ldr(scratch1, NativeContextMemOperand());
+  Ldr(scratch2,
+      ContextMemOperand(scratch1, Context::ArrayMapIndex(expected_kind)));
   Cmp(map_in_out, scratch2);
   B(ne, no_map_match);
 
   // Use the transitioned cached map.
-  offset = (transitioned_kind * kPointerSize) + FixedArrayBase::kHeaderSize;
-  Ldr(map_in_out, FieldMemOperand(scratch1, offset));
+  Ldr(map_in_out,
+      ContextMemOperand(scratch1, Context::ArrayMapIndex(transitioned_kind)));
 }
 
 
 void MacroAssembler::LoadNativeContextSlot(int index, Register dst) {
   Ldr(dst, NativeContextMemOperand());
   Ldr(dst, ContextMemOperand(dst, index));
 }
 
 
 void MacroAssembler::LoadGlobalFunctionInitialMap(Register function,
@@ skipping 429 matching lines @@
 }
 
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64