Add a vect_get_scalar_dr_size helper function

This patch adds a helper function for getting the number of bytes
accessed by an unvectorised data reference, which helps when general
modes have a variable size.

2017-09-22  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-vectorizer.h (vect_get_scalar_dr_size): New function.
	* tree-vect-data-refs.c (vect_update_misalignment_for_peel): Use it.
	(vect_enhance_data_refs_alignment): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r253099

gcc/ChangeLog

+2017-09-22  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
+	* tree-vectorizer.h (vect_get_scalar_dr_size): New function.
+	* tree-vect-data-refs.c (vect_update_misalignment_for_peel): Use it.
+	(vect_enhance_data_refs_alignment): Likewise.
+
 2017-09-22  Richard Earnshaw  <richard.earnshaw@arm.com>
 
 	* config/arm/parsecpu.awk (fatal): Note that we've encountered an

gcc/tree-vect-data-refs.c

@@ -955,7 +955,6 @@ vect_compute_data_ref_alignment (struct data_reference *dr)
   return true;
 }
 
-
 /* Function vect_update_misalignment_for_peel.
    Sets DR's misalignment
    - to 0 if it has the same alignment as DR_PEEL,
@@ -975,8 +974,8 @@ vect_update_misalignment_for_peel (struct data_reference *dr,
   unsigned int i;
   vec<dr_p> same_aligned_drs;
   struct data_reference *current_dr;
-  int dr_size = GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (DR_REF (dr))));
-  int dr_peel_size = GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (DR_REF (dr_peel))));
+  int dr_size = vect_get_scalar_dr_size (dr);
+  int dr_peel_size = vect_get_scalar_dr_size (dr_peel);
   stmt_vec_info stmt_info = vinfo_for_stmt (DR_STMT (dr));
   stmt_vec_info peel_stmt_info = vinfo_for_stmt (DR_STMT (dr_peel));
 
@@ -1664,8 +1663,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
 
               vectype = STMT_VINFO_VECTYPE (stmt_info);
               nelements = TYPE_VECTOR_SUBPARTS (vectype);
-              mis = DR_MISALIGNMENT (dr) / GET_MODE_SIZE (TYPE_MODE (
-                                                TREE_TYPE (DR_REF (dr))));
+	      mis = DR_MISALIGNMENT (dr) / vect_get_scalar_dr_size (dr);
 	      if (DR_MISALIGNMENT (dr) != 0)
 		npeel_tmp = (negative ? (mis - nelements)
 			     : (nelements - mis)) & (nelements - 1);
@@ -1937,8 +1935,7 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
                  updating DR_MISALIGNMENT values.  The peeling factor is the
                  vectorization factor minus the misalignment as an element
                  count.  */
-              mis = DR_MISALIGNMENT (dr0);
-              mis /= GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (DR_REF (dr0))));
+	      mis = DR_MISALIGNMENT (dr0) / vect_get_scalar_dr_size (dr0);
               npeel = ((negative ? mis - nelements : nelements - mis)
 		       & (nelements - 1));
             }

gcc/tree-vectorizer.h

@@ -1095,6 +1095,19 @@ vect_get_num_copies (loop_vec_info loop_vinfo, tree vectype)
 	  / TYPE_VECTOR_SUBPARTS (vectype));
 }
 
+/* Return the size of the value accessed by unvectorized data reference DR.
+   This is only valid once STMT_VINFO_VECTYPE has been calculated for the
+   associated gimple statement, since that guarantees that DR accesses
+   either a scalar or a scalar equivalent.  ("Scalar equivalent" here
+   includes things like V1SI, which can be vectorized in the same way
+   as a plain SI.)  */
+
+inline unsigned int
+vect_get_scalar_dr_size (struct data_reference *dr)
+{
+  return tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr))));
+}
+
 /* Source location */
 extern source_location vect_location;