re PR middle-end/31115 (libstdc++ 22_locale/num_get/get/char/2.cc 27_io/basic_ostream/inserters_arithmetic/char/6.cc)

2007-03-11  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/31115
	* tree-vrp.c (extract_range_from_binary_expr): Make sure
	the shift count is positive and non-anti-range for RSHIFT_EXPR.
	A shift count of zero is not special as with *_DIV_EXPR.
	(vrp_int_const_binop): Handle RSHIFT_EXPR for determining overflow
	direction.

	* gcc.dg/torture/pr31115.c: New testcase.

From-SVN: r122821