Re: [061/nnn] poly_int: compute_data_ref_alignment

[Jeff Law]

On 10/23/2017 11:25 AM, Richard Sandiford wrote:
> This patch makes vect_compute_data_ref_alignment treat DR_INIT as a
> poly_int and handles cases in which the calculated misalignment might
> not be constant.
> 
> 
> 2017-10-23  Richard Sandiford  
>   Alan Hayward  
>   David Sherwood  
> 
> gcc/
>   * tree-vect-data-refs.c (vect_compute_data_ref_alignment):
>   Treat drb->init as a poly_int.  Fail if its misalignment wrt
>   vector_alignment isn't known.
OK.
jeff

[061/nnn] poly_int: compute_data_ref_alignment

[Richard Sandiford]

This patch makes vect_compute_data_ref_alignment treat DR_INIT as a
poly_int and handles cases in which the calculated misalignment might
not be constant.


2017-10-23  Richard Sandiford  
Alan Hayward  
David Sherwood  

gcc/
* tree-vect-data-refs.c (vect_compute_data_ref_alignment):
Treat drb->init as a poly_int.  Fail if its misalignment wrt
vector_alignment isn't known.

Index: gcc/tree-vect-data-refs.c
===
--- gcc/tree-vect-data-refs.c   2017-10-23 17:22:18.234826257 +0100
+++ gcc/tree-vect-data-refs.c   2017-10-23 17:22:24.456074525 +0100
@@ -944,8 +944,8 @@ vect_compute_data_ref_alignment (struct
   DR_VECT_AUX (dr)->base_misaligned = true;
   base_misalignment = 0;
 }
-  unsigned int misalignment = (base_misalignment
-  + TREE_INT_CST_LOW (drb->init));
+  poly_int64 misalignment
+= base_misalignment + wi::to_poly_offset (drb->init).force_shwi ();
 
   /* If this is a backward running DR then first access in the larger
  vectype actually is N-1 elements before the address in the DR.
@@ -955,7 +955,21 @@ vect_compute_data_ref_alignment (struct
 misalignment += ((TYPE_VECTOR_SUBPARTS (vectype) - 1)
 * TREE_INT_CST_LOW (drb->step));
 
-  SET_DR_MISALIGNMENT (dr, misalignment & (vector_alignment - 1));
+  unsigned int const_misalignment;
+  if (!known_misalignment (misalignment, vector_alignment,
+  _misalignment))
+{
+  if (dump_enabled_p ())
+   {
+ dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+  "Non-constant misalignment for access: ");
+ dump_generic_expr (MSG_MISSED_OPTIMIZATION, TDF_SLIM, ref);
+ dump_printf (MSG_MISSED_OPTIMIZATION, "\n");
+   }
+  return true;
+}
+
+  SET_DR_MISALIGNMENT (dr, const_misalignment);
 
   if (dump_enabled_p ())
 {