poly_int: vector_alignment_reachable_p

This patch makes vector_alignment_reachable_p cope with variable-length
vectors.

2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-vect-data-refs.c (vector_alignment_reachable_p): Treat the
	number of units as polynomial.

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

From-SVN: r256132

gcc/ChangeLog

@@ -2,6 +2,13 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* tree-vect-data-refs.c (vector_alignment_reachable_p): Treat the
+	number of units as polynomial.
+
+2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* target.h (vector_sizes, auto_vector_sizes): New typedefs.
 	* target.def (autovectorize_vector_sizes): Return the vector sizes
 	by pointer, using vector_sizes rather than a bitmask.

gcc/tree-vect-data-refs.c

@@ -1154,16 +1154,17 @@ vector_alignment_reachable_p (struct data_reference *dr)
 	 the prolog loop ({VF - misalignment}), is a multiple of the
 	 number of the interleaved accesses.  */
       int elem_size, mis_in_elements;
-      int nelements = TYPE_VECTOR_SUBPARTS (vectype);
 
       /* FORNOW: handle only known alignment.  */
       if (!known_alignment_for_access_p (dr))
 	return false;
 
-      elem_size = GET_MODE_SIZE (TYPE_MODE (vectype)) / nelements;
+      poly_uint64 nelements = TYPE_VECTOR_SUBPARTS (vectype);
+      poly_uint64 vector_size = GET_MODE_SIZE (TYPE_MODE (vectype));
+      elem_size = vector_element_size (vector_size, nelements);
       mis_in_elements = DR_MISALIGNMENT (dr) / elem_size;
 
-      if ((nelements - mis_in_elements) % GROUP_SIZE (stmt_info))
+      if (!multiple_p (nelements - mis_in_elements, GROUP_SIZE (stmt_info)))
 	return false;
     }