2008-04-02  Richard Guenther  <rguenther@suse.de>

	* tree-vrp.c (extract_range_from_assert): Make sure to not
	produce range min/max with TREE_OVERFOW set.
	If merging a anti-range and a range keep the anti-range if
	the range covers all values of the type.
	(register_edge_assert_for_2): Only allow sign-changing
	conversions in detecting canonical range checks.  Also
	register an assert for the unsigned name if useful.

	PR tree-optimization/35787
	* tree-vrp.c (vrp_val_max): New function.
	(vrp_val_min): Likewise.
	(vrp_val_is_max): Move earlier, use vrp_val_{min,max}.
	(vrp_val_is_min): Likewise.
	(supports_overflow_infinity): Use vrp_val_{min,max}.
	(negative_overflow_infinity): Likewise.
	(positive_overflow_infinity): Likewise.
	(is_negative_overflow_infinity): Use vrp_val_is_{min,max}.
	(is_positive_overflow_infinity): Likewise.
	(is_overflow_infinity): Likewise.
	(avoid_overflow_infinity): Use vrp_val_{min,max} and
	vrp_val_is_{min,max}.
	(set_and_canonicalize_value_range): Canonicalize anti-ranges
	to ranges if possible.  Avoid empty ranges.

	* gcc.dg/tree-ssa/vrp38.c: New testcase.
	* gcc.dg/tree-ssa/vrp39.c: Likewise.

From-SVN: r133808