simplify-rtx.c (simplify_unary_operation_1): Optimize (sign_extend...

simplify-rtx.c (simplify_unary_operation_1): Optimize (sign_extend (zero_extend ()) and ({sign,zero}_extend (lshiftrt...

	* simplify-rtx.c (simplify_unary_operation_1): Optimize
	(sign_extend (zero_extend ()) and
	({sign,zero}_extend (lshiftrt (ashift X (const_int I)) (const_int I))).

Co-Authored-By: Paolo Bonzini <bonzini@gnu.org>

From-SVN: r163413