re PR rtl-optimization/57439 (FAIL: gcc.c-torture/execute/920501-6.c execution, -O1)

        PR rtl-optimization/57439
        * postreload.c (move2add_use_add2_insn): Use gen_lowpart_common.

From-SVN: r199387

gcc/ChangeLog

+2013-05-28  Joern Rennecke <joern.rennecke@embecosm.com>
+
+	PR rtl-optimization/57439
+	* postreload.c (move2add_use_add2_insn): Use gen_lowpart_common.
+
 2013-05-28  Easwaran Raman  <eraman@google.com>
 
 	PR tree-optimization/57337

gcc/postreload.c

@@ -1794,8 +1794,7 @@ move2add_use_add2_insn (rtx reg, rtx sym, rtx off, rtx insn)
 		  && ((reg_offset[regno] & ~GET_MODE_MASK (narrow_mode))
 		      == (INTVAL (off) & ~GET_MODE_MASK (narrow_mode))))
 		{
-		  rtx narrow_reg = gen_rtx_REG (narrow_mode,
-						REGNO (reg));
+		  rtx narrow_reg = gen_lowpart_common (narrow_mode, reg);
 		  rtx narrow_src = gen_int_mode (INTVAL (off),
 						 narrow_mode);
 		  rtx new_set