match.pd: Implement missed optimization (~X | Y) ^ X -> ~(X & Y) [PR109986]

match.pd: Implement missed optimization (~X | Y) ^ X -> ~(X & Y) [PR109986]

Adds a simplification for (~X | Y) ^ X to be folded into ~(X & Y).
Also adds the macro bitwise_equal_p for generic and gimple which
returns true iff EXPR1 and EXPR2 have the same value. This helps
to reduce the number of nop_converts necessary to match the pattern.

	PR middle-end/109986

gcc/ChangeLog:

	* generic-match-head.cc (bitwise_equal_p): New macro.
	* gimple-match-head.cc (bitwise_equal_p): New macro.
	(gimple_nop_convert): Declare.
	(gimple_bitwise_equal_p): Helper for bitwise_equal_p.
	* match.pd ((~X | Y) ^ X -> ~(X & Y)): New simplification.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/execute/pr109986.c: New test.
	* gcc.dg/tree-ssa/pr109986.c: New test.

Co-authored-by: Jakub Jelinek <jakub@redhat.com>