PR tree-optimization/18431
	* fold-const.c (associate_trees): Do not produce x + 0.
	(fold_widened_comparison, fold_sign_changed_comparison): New functions.
	(fold): Use them.
	* tree-ssa-loop-niter.c (upper_bound_in_type, lower_bound_in_type):
	Moved ...
	* tree.c (upper_bound_in_type, lower_bound_in_type): Here.
	* tree.h (upper_bound_in_type, lower_bound_in_type): Declare.

	* testsuite/gcc.c-torture/execute/20041114-1.c: New test.

From-SVN: r90646