match.pd: Simplify unsigned A - B - 1 >= A to B >= A [PR94913]

match.pd: Simplify unsigned A - B - 1 >= A to B >= A [PR94913]

Implemented thusly.  The TYPE_OVERFLOW_WRAPS is there just because the
pattern above it has it too, if you want, I can throw it away from both.

2020-05-08  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94913
	* match.pd (A - B + -1 >= A to B >= A): New simplification.
	(A - B > A to A < B): Don't test TYPE_OVERFLOW_WRAPS which is always
	true for TYPE_UNSIGNED integral types.

	* gcc.dg/tree-ssa/pr94913.c: New test.