Add complete ElementKind information directly to Map for objects with elements.

src/arm/full-codegen-arm.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 3415 matching lines @@
 
   // Separator operand is on the stack.
   __ pop(separator);
 
   // Check that the array is a JSArray.
   __ JumpIfSmi(array, &bailout);
   __ CompareObjectType(array, scratch1, scratch2, JS_ARRAY_TYPE);
   __ b(ne, &bailout);
 
   // Check that the array has fast elements.
-  __ ldrb(scratch2, FieldMemOperand(scratch1, Map::kBitField2Offset));
-  __ tst(scratch2, Operand(1 << Map::kHasFastElements));
-  __ b(eq, &bailout);
+  __ CheckFastElements(scratch1, scratch2, &bailout);
 
   // If the array has length zero, return the empty string.
   __ ldr(array_length, FieldMemOperand(array, JSArray::kLengthOffset));
   __ SmiUntag(array_length, SetCC);
   __ b(ne, &non_trivial_array);
   __ LoadRoot(r0, Heap::kEmptyStringRootIndex);
   __ b(&done);
 
   __ bind(&non_trivial_array);
 
@@ skipping 917 matching lines @@
   __ mov(r1, Operand(r1, ASR, 1));  // Un-smi-tag value.
   __ add(pc, r1, Operand(masm_->CodeObject()));
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM