re PR tree-optimization/57558 (Loop not vectorized if iteration count could be infinite)

re PR tree-optimization/57558 (Loop not vectorized if iteration count could be infinite)

	PR tree-optimization/57558
	* tree-vect-loop-manip.c (vect_create_cond_for_niters_checks): New
	function.
	(vect_loop_versioning): Support versioning with niter assumptions.
	* tree-vect-loop.c (tree-ssa-loop.h): Include header file.
	(vect_get_loop_niters): New parameter.  Reimplement to support
	assumptions in loop niter info.
	(vect_analyze_loop_form_1, vect_analyze_loop_form): Ditto.
	(new_loop_vec_info): Init LOOP_VINFO_NITERS_ASSUMPTIONS.
	(vect_estimate_min_profitable_iters): Use LOOP_REQUIRES_VERSIONING.
	Support loop versioning for niters.
	* tree-vectorizer.c (tree-ssa-loop-niter.h): Include header file.
	(vect_free_loop_info_assumptions): New function.
	(vectorize_loops): Free loop niter info for loops with flag
	LOOP_F_ASSUMPTIONS set if vectorization failed.
	* tree-vectorizer.h (struct _loop_vec_info): New field
	num_iters_assumptions.
	(LOOP_VINFO_NITERS_ASSUMPTIONS): New macro.
	(LOOP_REQUIRES_VERSIONING_FOR_NITERS): New macro.
	(LOOP_REQUIRES_VERSIONING): New macro.
	(vect_free_loop_info_assumptions): New decl.

	gcc/testsuite
	PR tree-optimization/57558
	* gcc.dg/vect/pr57558-1.c: New test.
	* gcc.dg/vect/pr57558-2.c: New test.

From-SVN: r238877