tree-optimization/96522 - transfer of flow-sensitive info in copy_ref_info

tree-optimization/96522 - transfer of flow-sensitive info in copy_ref_info

This removes the bogus tranfer of flow-sensitive info in copy_ref_info
plus fixes one oversight in FRE when flow-sensitive non-NULLness was added to
points-to info.

2020-08-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/96522
	* tree-ssa-address.c (copy_ref_info): Reset flow-sensitive
	info of the copied points-to.  Transfer bigger alignment
	via the access type.
	* tree-ssa-sccvn.c (eliminate_dom_walker::eliminate_stmt):
	Reset all flow-sensitive info.

	* gcc.dg/torture/pr96522.c: New testcase.

(cherry picked from commit eb68d9d828f94d28afa5900fbf3072bbcd64ba8a)