fold-const.c (negate_expr_p): We can optimize -((int)X>>C) where C is an integer constant one bit less than...


	* fold-const.c (negate_expr_p) <RSHIFT_EXPR>: We can optimize
	-((int)X>>C) where C is an integer constant one bit less than the
	size of X into (unsigned)X>>C.  Similarly for unsigned->signed.
	(negate_expr) <RSHIFT_EXPR>: Implement the above transformations.

	* simplify-rtx.c (simplify_unary_operation): Also implement the
	above transformations at the RTL level.

	* gcc.c-torture/execute/20040311-1.c: New test case.

From-SVN: r79334