* match.pd (bit_and (plus/minus (convert @0) (convert @1) mask): New
	simplifier to narrow arithmetic.
	* generic-match-head.c: (types_match, single_use): New functions.
	* gimple-match-head.c: (types_match, single_use): New functions.

	* gcc.dg/tree-ssa/shorten-1.c: New test.

From-SVN: r222877