[ARC] Fix move_double_src_operand predicate.

Durring compilation process, (subreg (mem ...) ...) can occur. Hence,
we need to check if the address of mem is a valid one. This patch is
fixing this check by directly calling the address_operand, instead of
calling move_double_src_operand, as the latter is always checking
against the original mode, thus, returning false when the inner and
outer modes are different.

gcc/
2017-03-27  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/predicates.md (move_double_src_operand): Replace the
	call to move_double_src_operand with a call to address_operand.

From-SVN: r246499

gcc/ChangeLog

 2017-03-27  Claudiu Zissulescu  <claziss@synopsys.com>
 
+	* config/arc/predicates.md (move_double_src_operand): Replace the
+	call to move_double_src_operand with a call to address_operand.
+
+2017-03-27  Claudiu Zissulescu  <claziss@synopsys.com>
+
 	* config/arc/elf.h (ARGET_ARC_TP_REGNO_DEFAULT): Define.
 	* config/arc/linux.h (ARGET_ARC_TP_REGNO_DEFAULT): Likewise.
 	* config/arc/arc.opt (mtp-regno): Use ARGET_ARC_TP_REGNO_DEFAULT.

gcc/config/arc/predicates.md

@@ -318,7 +318,7 @@
       /* (subreg (mem ...) ...) can occur here if the inner part was once a
 	 pseudo-reg and is now a stack slot.  */
       if (GET_CODE (SUBREG_REG (op)) == MEM)
-	return move_double_src_operand (SUBREG_REG (op), mode);
+	return address_operand (XEXP (SUBREG_REG (op), 0), mode);
       else
 	return register_operand (op, mode);
     case MEM :