middle-end: Refactor vectorizer loop conditionals and separate out IV to new variables

This is extracted out of the patch series to support early break vectorization
in order to simplify the review of that patch series.

The goal of this one is to separate out the refactoring from the new
functionality.

This first patch separates out the vectorizer's definition of an exit to their
own values inside loop_vinfo.  During vectorization we can have three separate
copies for each loop: scalar, vectorized, epilogue.  The scalar loop can also be
the versioned loop before peeling.

Because of this we track 3 different exits inside loop_vinfo corresponding to
each of these loops.  Additionally each function that uses an exit, when not
obviously clear which exit is needed will now take the exit explicitly as an
argument.

This is because often times the callers switch the loops being passed around.
While the caller knows which loops it is, the callee does not.

For now the loop exits are simply initialized to same value as before determined
by single_exit (..).

No change in functionality is expected throughout this patch series.

gcc/ChangeLog:

	* tree-loop-distribution.cc (copy_loop_before): Pass exit explicitly.
	(loop_distribution::distribute_loop): Bail out of not single exit.
	* tree-scalar-evolution.cc (get_loop_exit_condition): New.
	* tree-scalar-evolution.h (get_loop_exit_condition): New.
	* tree-vect-data-refs.cc (vect_enhance_data_refs_alignment): Pass exit
	explicitly.
	* tree-vect-loop-manip.cc (vect_set_loop_condition_partial_vectors,
	vect_set_loop_condition_partial_vectors_avx512,
	vect_set_loop_condition_normal, vect_set_loop_condition): Explicitly
	take exit.
	(slpeel_tree_duplicate_loop_to_edge_cfg): Explicitly take exit and
	return new peeled corresponding peeled exit.
	(slpeel_can_duplicate_loop_p): Explicitly take exit.
	(find_loop_location): Handle not knowing an explicit exit.
	(vect_update_ivs_after_vectorizer, vect_gen_vector_loop_niters_mult_vf,
	find_guard_arg, slpeel_update_phi_nodes_for_loops,
	slpeel_update_phi_nodes_for_guard2): Use new exits.
	(vect_do_peeling): Update bookkeeping to keep track of exits.
	* tree-vect-loop.cc (vect_get_loop_niters): Explicitly take exit to
	analyze.
	(vec_init_loop_exit_info): New.
	(_loop_vec_info::_loop_vec_info): Initialize vec_loop_iv,
	vec_epilogue_loop_iv, scalar_loop_iv.
	(vect_analyze_loop_form): Initialize exits.
	(vect_create_loop_vinfo): Set main exit.
	(vect_create_epilog_for_reduction, vectorizable_live_operation,
	vect_transform_loop): Use it.
	(scale_profile_for_vect_loop): Explicitly take exit to scale.
	* tree-vectorizer.cc (set_uid_loop_bbs): Initialize loop exit.
	* tree-vectorizer.h (LOOP_VINFO_IV_EXIT, LOOP_VINFO_EPILOGUE_IV_EXIT,
	LOOP_VINFO_SCALAR_IV_EXIT): New.
	(struct loop_vec_info): Add vec_loop_iv, vec_epilogue_loop_iv,
	scalar_loop_iv.
	(vect_set_loop_condition, slpeel_can_duplicate_loop_p,
	slpeel_tree_duplicate_loop_to_edge_cfg): Take explicit exits.
	(vec_init_loop_exit_info): New.
	(struct vect_loop_form_info): Add loop_exit.

1 files changed, 2 insertions, 1 deletions

diff --git a/gcc/tree-loop-distribution.cc b/gcc/tree-loop-distribution.cc
index 39fd440..2cafd01 100644
--- a/gcc/tree-loop-distribution.cc
+++ b/gcc/tree-loop-distribution.cc
@@ -949,7 +949,8 @@ copy_loop_before (class loop *loop, bool redirect_lc_phi_defs)
   edge preheader = loop_preheader_edge (loop);
 
   initialize_original_copy_tables ();
-  res = slpeel_tree_duplicate_loop_to_edge_cfg (loop, NULL, preheader);
+  res = slpeel_tree_duplicate_loop_to_edge_cfg (loop, single_exit (loop), NULL,
+						NULL, preheader, NULL);
   gcc_assert (res != NULL);
 
   /* When a not last partition is supposed to keep the LC PHIs computed