Fix for issue 171:...

src/stub-cache-arm.cc

 // Copyright 2006-2008 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 294 matching lines @@
   // Check that the object is a string.
   __ ldr(scratch1, FieldMemOperand(receiver, HeapObject::kMapOffset));
   __ ldrb(scratch1, FieldMemOperand(scratch1, Map::kInstanceTypeOffset));
   __ and_(scratch2, scratch1, Operand(kIsNotStringMask));
   // The cast is to resolve the overload for the argument of 0x0.
   __ cmp(scratch2, Operand(static_cast<int32_t>(kStringTag)));
   __ b(ne, non_string_object);
 }
 
 
+// Generate code to load the length from a string object and return the length.
+// If the receiver object is not a string or a wrapped string object the
+// execution continues at the miss label. The register containing the
+// receiver is potentially clobbered.
 void StubCompiler::GenerateLoadStringLength2(MacroAssembler* masm,
                                              Register receiver,
                                              Register scratch1,
                                              Register scratch2,
                                              Label* miss) {
-  Label load_length, check_wrapper;
+  Label check_string, check_wrapper;
 
+  __ bind(&check_string);
   // Check if the object is a string leaving the instance type in the
   // scratch1 register.
   GenerateStringCheck(masm, receiver, scratch1, scratch2,
                       miss, &check_wrapper);
 
   // Load length directly from the string.
-  __ bind(&load_length);
   __ and_(scratch1, scratch1, Operand(kStringSizeMask));
   __ add(scratch1, scratch1, Operand(String::kHashShift));
   __ ldr(r0, FieldMemOperand(receiver, String::kLengthOffset));
   __ mov(r0, Operand(r0, LSR, scratch1));
   __ mov(r0, Operand(r0, LSL, kSmiTagSize));
   __ Ret();
 
   // Check if the object is a JSValue wrapper.
   __ bind(&check_wrapper);
   __ cmp(scratch1, Operand(JS_VALUE_TYPE));
   __ b(ne, miss);
 
-  // Check if the wrapped value is a string and load the length
-  // directly if it is.
-  __ ldr(r0, FieldMemOperand(receiver, JSValue::kValueOffset));
-  GenerateStringCheck(masm, receiver, scratch1, scratch1, miss, miss);
-  __ b(&load_length);
+  // Unwrap the value in place and check if the wrapped value is a string.
+  __ ldr(receiver, FieldMemOperand(receiver, JSValue::kValueOffset));
+  __ b(&check_string);
 }
 
 
 // Generate StoreField code, value is passed in r0 register.
 // After executing generated code, the receiver_reg and name_reg
 // may be clobbered.
 void StubCompiler::GenerateStoreField(MacroAssembler* masm,
                                       Builtins::Name storage_extend,
                                       JSObject* object,
                                       int index,
@@ skipping 781 matching lines @@
   __ Jump(ic, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode(transition == NULL ? FIELD : MAP_TRANSITION);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal