re PR middle-end/78726 (Incorrect unsigned arithmetic optimization)

re PR middle-end/78726 (Incorrect unsigned arithmetic optimization)

	PR tree-optimization/78726
	* tree-ssa-reassoc.c (make_new_ssa_for_def): Add OPCODE and OP
	argument.  For lhs uses in debug stmts, don't replace lhs with
	new_lhs, but with a debug temp set to new_lhs opcode op.
	(make_new_ssa_for_all_defs): Add OPCODE argument, pass OPCODE and
	OP down to make_new_ssa_for_def.
	(zero_one_operation): Call make_new_ssa_for_all_defs even when
	stmts_to_fix is empty, if *def has not changed yet.  Pass
	OPCODE to make_new_ssa_for_all_defs.

	* gcc.c-torture/execute/pr78726.c: New test.
	* gcc.dg/guality/pr78726.c: New test.

From-SVN: r243476