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

src/arm/macro-assembler-arm.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.
 
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
@@ skipping 2642 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);
-  size_t offset = expected_kind * kPointerSize + FixedArrayBase::kHeaderSize;
-  ldr(ip, FieldMemOperand(scratch, offset));
+  ldr(scratch, NativeContextMemOperand());
+  ldr(ip, ContextMemOperand(scratch, Context::ArrayMapIndex(expected_kind)));
   cmp(map_in_out, ip);
   b(ne, no_map_match);
 
   // Use the transitioned cached map.
-  offset = transitioned_kind * kPointerSize +
-      FixedArrayBase::kHeaderSize;
-  ldr(map_in_out, FieldMemOperand(scratch, offset));
+  ldr(map_in_out,
+      ContextMemOperand(scratch, 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 997 matching lines @@
     }
   }
   if (mag.shift > 0) mov(result, Operand(result, ASR, mag.shift));
   add(result, result, Operand(dividend, LSR, 31));
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM