Relax trap assumptions in tree if convert.

Relax trap assumptions in tree if convert.

2015-11-17  Venkataramanan Kumar  <Venkataramanan.Kumar@amd.com>

	* tree-if-conv.c: Include varasm.h
	(ref_DR_map): Define.
	(baseref_DR_map): Like wise
	(struct ifc_dr): Add new tree predicate field.
	(hash_memrefs_baserefs_and_store_DRs_read_written_info): New function.
	(memrefs_read_or_written_unconditionally): Remove.
	(write_memrefs_written_at_least_once): Remove.
	(ifcvt_memrefs_wont_trap): Use hash maps to query
	unconditional read/written information.
	(if_convertible_loop_p_1):  Initialize hash maps and predicates
	before hashing data references and delete hashmaps at the end.

2015-11-17  Venkataramanan Kumar  <Venkataramanan.Kumar@amd.com>

	* gcc.dg/tree-ssa/ifc-8.c: New test.

From-SVN: r230454