re PR middle-end/91866 (Sign extend of an int is not recognized)

	PR middle-end/91866
	* match.pd (((T)(A)) + CST -> (T)(A + CST)): Formatting fix.
	(((T)(A + CST1)) + CST2 -> (T)(A) + (T)CST1 + CST2): New optimization.

	* gcc.dg/tree-ssa/pr91866.c: New test.

From-SVN: r276096