poly_int: indirect_refs_may_alias_p

poly_int: indirect_refs_may_alias_p

This patch makes indirect_refs_may_alias_p use ranges_may_overlap_p
rather than ranges_overlap_p.  Unlike the former, the latter can handle
negative offsets, so the fix for PR44852 should no longer be necessary.
It can also handle offset_int, so avoids unchecked truncations to
HOST_WIDE_INT.

2017-12-20  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p)
	(indirect_refs_may_alias_p): Use ranges_may_overlap_p
	instead of ranges_overlap_p.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r255871