Fix keyed element access wrt string wrappers

src/ic/arm64/ic-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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/codegen.h"
 #include "src/ic/ic.h"
@@ skipping 639 matching lines @@
   // Check that the receiver does not require access checks and is not observed.
   // The generic stub does not perform map checks or handle observed objects.
   __ Ldrb(x10, FieldMemOperand(receiver_map, Map::kBitFieldOffset));
   __ TestAndBranchIfAnySet(
       x10, (1 << Map::kIsAccessCheckNeeded) | (1 << Map::kIsObserved), &slow);
 
   // Check if the object is a JS array or not.
   Register instance_type = x10;
   __ CompareInstanceType(receiver_map, instance_type, JS_ARRAY_TYPE);
   __ B(eq, &array);
-  // Check that the object is some kind of JSObject.
-  __ Cmp(instance_type, FIRST_JS_OBJECT_TYPE);
+  // Check that the object is some kind of JS object EXCEPT JS Value type. In
+  // the case that the object is a value-wrapper object, we enter the runtime
+  // system to make sure that indexing into string objects works as intended.
+  DCHECK(JS_VALUE_TYPE < JS_OBJECT_TYPE);
+  __ Cmp(instance_type, JS_OBJECT_TYPE);
   __ B(lt, &slow);

[Jakob Kummerow, 2015/07/13 15:00:58]

s/lt/lo/ for unsigned comparison

 
   // Object case: Check key against length in the elements array.
   __ Ldr(elements, FieldMemOperand(receiver, JSObject::kElementsOffset));
   // Check array bounds. Both the key and the length of FixedArray are smis.
   __ Ldrsw(x10, UntagSmiFieldMemOperand(elements, FixedArray::kLengthOffset));
   __ Cmp(x10, Operand::UntagSmi(key));
   __ B(hi, &fast_object);
 
 
   __ Bind(&slow);
@@ skipping 208 matching lines @@
   } else {
     DCHECK(to_patch->Mask(TestBranchMask) == TBNZ);
     // This is JumpIfSmi(smi_reg, branch_imm).
     patcher.tbz(smi_reg, 0, branch_imm);
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64