re PR tree-optimization/68583 (Missed if-conversion)

re PR tree-optimization/68583 (Missed if-conversion)

2015-12-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/68583
	* tree-if-conv.c (ifc_dr): Make flags bool, add w_unconditionally
	flag and rename predicates to w_predicate, rw_predicate and
	base_w_predicate.
	(DR_WRITTEN_AT_LEAST_ONCE): Rename to ...
	(DR_BASE_W_UNCONDITIONALLY): ... this.
	(DR_W_UNCONDITIONALLY): Add.
	(hash_memrefs_baserefs_and_store_DRs_read): Adjust.  Compute
	unconditionally written separately from read or written.
	(ifcvt_memrefs_wont_trap): Properly treat reads.
	(ifcvt_could_trap_p): Inline ...
	(if_convertible_gimple_assign_stmt_p): ... here.  Refactor
	to avoid code duplication.
	(if_convertible_loop_p_1): Adjust and properly initialize
	predicates.

From-SVN: r231444