fold-const.c (fold_unary_loc): Move abs(abs(x)) -> abs(x)...

fold-const.c (fold_unary_loc): Move abs(abs(x)) -> abs(x)...

2015-06-30  Richard Biener  <rguenther@suse.de>

	* fold-const.c (fold_unary_loc): Move abs(abs(x)) -> abs(x),
	~ (-A) to A - 1, ~ (A - 1) or ~ (A + -1) to -A and some cases of
	~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify to ...
	* match.pd: ... here.
	Add a few cases of A - B -> A + (-B) when B "easily" negates.
	Move (x & y) | x -> x and friends before
	(x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2).

From-SVN: r225178