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Re: [PATCH, vec-tails 07/10] Support loop epilogue combining

On 06/28/2016 06:24 AM, Ilya Enkovich wrote:

Here is an updated patch version.


2016-05-28  Ilya Enkovich  <>

	* dbgcnt.def (vect_tail_combine): New.
	* tree-vect-data-refs.c (vect_get_new_ssa_name): Support vect_mask_var.
	* tree-vect-loop-manip.c (slpeel_tree_peel_loop_to_edge): Support
	epilogue combined with loop body.
	(vect_do_peeling_for_loop_bound): LIkewise.
	(vect_do_peeling_for_alignment): ???
	* tree-vect-loop.c Include alias.h and dbgcnt.h.
	(vect_estimate_min_profitable_iters): Add ret_min_profitable_combine_niters
	arg, compute number of iterations for which loop epilogue combining is
	(vect_generate_tmps_on_preheader): Support combined apilogue.
	(vect_gen_ivs_for_masking): New.
	(vect_get_mask_index_for_elems): New.
	(vect_get_mask_index_for_type): New.
	(vect_gen_loop_masks): New.
	(vect_mask_reduction_stmt): New.
	(vect_mask_mask_load_store_stmt): New.
	(vect_mask_load_store_stmt): New.
	(vect_combine_loop_epilogue): New.
	(vect_transform_loop): Support combined apilogue.

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 41b9380..08fad82 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -6895,6 +7044,489 @@ vect_generate_tmps_on_preheader (loop_vec_info loop_vinfo,

+/* Function vect_gen_loop_masks.
+   Create masks to mask a loop described by LOOP_VINFO.  Masks
+   are created according to LOOP_VINFO_REQUIRED_MASKS and are stored
+   into MASKS vector.
+   Index of a mask in a vector is computed according to a number
+   of masks's elements.  Masks are sorted by number of its elements
+   in descending order.  Index 0 is used to access a mask with
+   current_vector_size elements.  Among masks with the same number
+   of elements the one with lower index is used to mask iterations
+   with smaller iteration counter.  Note that you may get NULL elements
+   for masks which are not required.  Use vect_get_mask_index_for_elems
+   or vect_get_mask_index_for_type to access resulting vector.  */
+static void
+vect_gen_loop_masks (loop_vec_info loop_vinfo, vec<tree> *masks)
I find myself wondering if this ought to be broken down a bit (without changing the underlying semantics).

+  /* Create narrowed masks.  */
+  cur_mask_elems = iv_elems;
+  nmasks = ivs.length ();
+  while (cur_mask_elems < max_mask_elems)
+    {
+      prev_mask = vect_get_mask_index_for_elems (cur_mask_elems);
+      cur_mask_elems <<= 1;
+      nmasks >>= 1;
+      cur_mask = vect_get_mask_index_for_elems (cur_mask_elems);
+      mask_type = build_truth_vector_type (cur_mask_elems, vec_size);
+      for (unsigned i = 0; i < nmasks; i++)
+	{
+	  tree mask_low = (*masks)[prev_mask++];
+	  tree mask_hi = (*masks)[prev_mask++];
+	  mask = vect_get_new_ssa_name (mask_type, vect_mask_var);
+	  stmt = gimple_build_assign (mask, VEC_PACK_TRUNC_EXPR,
+				      mask_low, mask_hi);
+	  gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
+	  (*masks)[cur_mask++] = mask;
+	}
+    }
For example, pull this into its own function as well as the code to create widened masks. In fact, didn't I see those functions in one of the other patches as their own separate subroutines?

It's not a huge deal and I don't think it requires another round of review. I just found myself scrolling through multiple pages of this function and thought it'd be slightly easier to grok if were simply smaller.

+/* Function vect_mask_reduction_stmt.
+   Mask given vectorized reduction statement STMT using
+   MASK.  In case scalar reduction statement is vectorized
+   into several vector statements then PREV holds a
+   preceding vetor statement copy for STMT.

With the one function split up and the typo fix I think this is OK for the trunk when the set as a whole is ready.


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