correct usage of string comparison in MakeNames and Slot

Author: lukasstadler

com.oracle.truffle.r.nodes.builtin/src/com/oracle/truffle/r/nodes/builtin/base/MakeNames.java

@@ -176,7 +176,7 @@ protected RAbstractStringVector makeNames(RAbstractStringVector names, byte allo
                             newNames = updateNewNames(names, reuse, namesIter.getIndex(), newName, newNames);
                         } else {
                             newName = getName(name, allowUnderscore);
-                            if (!Utils.identityEquals(newName, name)) {
+                            if (!Utils.fastPathIdentityEquals(newName, name)) {
                                 // getName returns "name" in case nothing's changed
                                 newNames = updateNewNames(names, reuse, namesIter.getIndex(), newName, newNames);
                             }

com.oracle.truffle.r.nodes.builtin/src/com/oracle/truffle/r/nodes/builtin/base/Slot.java

@@ -64,7 +64,7 @@ public String execute(Object nameObj) {
             CompilerDirectives.transferToInterpreterAndInvalidate();
             value = getValue(nameObj);
         }
-        if (Utils.identityEquals(value, ERROR_MARKER)) {
+        if (Utils.fastPathIdentityEquals(value, ERROR_MARKER)) {
             CompilerDirectives.transferToInterpreter();
             throw RError.error(RError.NO_CALLER, RError.Message.GENERIC, "invalid type or length for slot name");
         }