tree-optimization/100519 - avoid reassociating asm goto defs

tree-optimization/100519 - avoid reassociating asm goto defs

This splits can_associate_p into checks for SSA defs and checks
for the type so it can be called from is_reassociable_op to
catch cases not catched by the earlier fix.

2021-05-11  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100519
	* tree-ssa-reassoc.c (can_associate_p): Split into...
	(can_associate_op_p): ... this
	(can_associate_type_p): ... and this.
	(is_reassociable_op): Call can_associate_op_p.
	(break_up_subtract_bb): Call the appropriate predicates.
	(reassociate_bb): Likewise.

	* gcc.dg/torture/pr100519.c: New testcase.