re PR tree-optimization/77536 (Vectorizer not maintaining relationship of relative block frequencies in absence of real profile data)

	PR tree-optimization/77536
	* tree-ssa-loop-manip.c (niter_for_unrolled_loop): New function.
	(tree_transform_and_unroll_loop): Use above function to compute the
	estimated niter of unrolled loop and use it when scaling profile.
	Also use count info rather than frequency if it's non-zero.
	* tree-ssa-loop-manip.h niter_for_unrolled_loop(): New declaration.
	* tree-vect-loop.c (scale_profile_for_vect_loop): New function.
	(vect_transform_loop): Call above function.

	gcc/testsuite
	* gcc.dg/vect/pr79347.c: Revise testing string.

From-SVN: r245754