PR middle-end/40815
	* tree-ssa-reassoc.c (broken_up_substracts): Rename to plus_negates.
	(negate_value): Move code to push elements to broken_up_substracts ...
	(eliminate_plus_minus_pair): ... here.  Push operands that have no
	negative pair to plus_negates.
	(repropagate_negates, init_reassoc, fini_reassoc): Update.

	PR middle-end/40815
	* gcc.dg/tree-ssa/reassoc-19.c: New.

From-SVN: r158105