2017-02-17  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/79529
	* tree-ssa-loop-unswitch.c (is_maybe_undefined): Use
	ssa_defined_default_def_p to handle cases which are implicitly
	defined.
	* tree-ssa.c (ssa_defined_default_def_p): New function.
	(ssa_undefined_value_p): Use ssa_defined_default_def_p to handle cases
	which are implicitly defined.
	* tree-ssa.h (ssa_defined_default_def_p): Declare.

From-SVN: r245530