PR tree-optimization/81555

	PR tree-optimization/81555
	PR tree-optimization/81556
	* tree-ssa-reassoc.c (rewrite_expr_tree): Add NEXT_CHANGED argument,
	if true, force CHANGED for the recursive invocation.
	(reassociate_bb): Remember original length of ops array, pass
	len != orig_len as NEXT_CHANGED in rewrite_expr_tree call.

	* gcc.c-torture/execute/pr81555.c: New test.
	* gcc.c-torture/execute/pr81556.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@250609 138bc75d-0d04-0410-961f-82ee72b054a4