re PR rtl-optimization/83628 (performance regression when accessing arrays on alpha)

	PR target/83628
	* combine.c (force_int_to_mode) <case ASHIFT>: Use mode instead of
	op_mode in the force_to_mode call.

From-SVN: r256387

gcc/ChangeLog

+2018-01-09  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR target/83628
+	* combine.c (force_int_to_mode) <case ASHIFT>: Use mode instead of
+	op_mode in the force_to_mode call.
+
 2018-01-09  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* config/aarch64/aarch64.c (aarch64_evpc_trn): Use d.perm.series_p

gcc/combine.c

@@ -8908,7 +8908,7 @@ force_int_to_mode (rtx x, scalar_int_mode mode, scalar_int_mode xmode,
 	mask = fuller_mask;
 
       op0 = gen_lowpart_or_truncate (op_mode,
-				     force_to_mode (XEXP (x, 0), op_mode,
+				     force_to_mode (XEXP (x, 0), mode,
 						    mask, next_select));
 
       if (op_mode != xmode || op0 != XEXP (x, 0))