A64: Fix result in CompileStringCharAtCall and CompileStringCharCodeAtCall.

src/a64/stub-cache-a64.cc

 // Copyright 2013 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 2031 matching lines @@
   generator.GenerateFast(masm());
   __ Drop(argc + 1);
   __ Mov(x0, result);
   __ Ret();
 
   StubRuntimeCallHelper call_helper;
   generator.GenerateSlow(masm(), call_helper);
 
   if (index_out_of_range.is_linked()) {
     __ Bind(&index_out_of_range);
-    __ LoadRoot(result, Heap::kNanValueRootIndex);
+    __ LoadRoot(x0, Heap::kNanValueRootIndex);
     __ Drop(argc + 1);
     __ Ret();
   }
 
   __ Bind(&miss);
   // Restore function name in x2.
   __ Mov(x2, Operand(name));
   __ Bind(&name_miss);
   GenerateMissBranch();
 
@@ skipping 48 matching lines @@
   generator.GenerateFast(masm());
   __ Drop(argc + 1);
   __ Mov(x0, result);
   __ Ret();
 
   StubRuntimeCallHelper call_helper;
   generator.GenerateSlow(masm(), call_helper);
 
   if (index_out_of_range.is_linked()) {
     __ Bind(&index_out_of_range);
-    __ LoadRoot(result, Heap::kempty_stringRootIndex);
+    __ LoadRoot(x0, Heap::kempty_stringRootIndex);
     __ Drop(argc + 1);
     __ Ret();
   }
 
   __ Bind(&miss);
   // Restore function name in x2.
   __ Mov(x2, Operand(name));
   __ Bind(&name_miss);
   GenerateMissBranch();
 
@@ skipping 874 matching lines @@
 
   // Miss case, call the runtime.
   __ Bind(&miss);
   TailCallBuiltin(masm, Builtins::kKeyedLoadIC_Miss);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_A64