Handle variable-length vectors in compute_record_mode

This patch makes compute_record_mode handle SVE vectors in the
same way as it would handle fixed-length vectors.  There should
be no change in behaviour for other targets.

This is needed for the SVE equivalent of arm_neon.h types like
int8x8x2_t (i.e. a pair of int8x8_ts).

2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* stor-layout.c (compute_record_mode): Operate on poly_uint64
	sizes instead of uhwi sizes.

From-SVN: r275869

gcc/ChangeLog

 2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* stor-layout.c (compute_record_mode): Operate on poly_uint64
+	sizes instead of uhwi sizes.
+
+2019-09-18  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* dwarf2out.c (loc_list_from_tree_1): Handle POLY_INT_CST.
 	(add_const_value_attribute): Handle CONST_POLY_INT.
 

gcc/stor-layout.c

@@ -1811,7 +1811,8 @@ compute_record_mode (tree type)
      line.  */
   SET_TYPE_MODE (type, BLKmode);
 
-  if (! tree_fits_uhwi_p (TYPE_SIZE (type)))
+  poly_uint64 type_size;
+  if (!poly_int_tree_p (TYPE_SIZE (type), &type_size))
     return;
 
   /* A record which has any BLKmode members must itself be
@@ -1822,20 +1823,21 @@ compute_record_mode (tree type)
       if (TREE_CODE (field) != FIELD_DECL)
 	continue;
 
+      poly_uint64 field_size;
       if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
 	  || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
 	      && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
 	      && !(TYPE_SIZE (TREE_TYPE (field)) != 0
 		   && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
-	  || ! tree_fits_uhwi_p (bit_position (field))
+	  || !tree_fits_poly_uint64_p (bit_position (field))
 	  || DECL_SIZE (field) == 0
-	  || ! tree_fits_uhwi_p (DECL_SIZE (field)))
+	  || !poly_int_tree_p (DECL_SIZE (field), &field_size))
 	return;
 
       /* If this field is the whole struct, remember its mode so
 	 that, say, we can put a double in a class into a DF
 	 register instead of forcing it to live in the stack.  */
-      if (simple_cst_equal (TYPE_SIZE (type), DECL_SIZE (field))
+      if (known_eq (field_size, type_size)
 	  /* Partial int types (e.g. __int20) may have TYPE_SIZE equal to
 	     wider types (e.g. int32), despite precision being less.  Ensure
 	     that the TYPE_MODE of the struct does not get set to the partial
@@ -1855,7 +1857,6 @@ compute_record_mode (tree type)
      For UNION_TYPE, if the widest field is MODE_INT then use that mode.
      If the widest field is MODE_PARTIAL_INT, and the union will be passed
      by reference, then use that mode.  */
-  poly_uint64 type_size;
   if ((TREE_CODE (type) == RECORD_TYPE
        || (TREE_CODE (type) == UNION_TYPE
 	   && (GET_MODE_CLASS (mode) == MODE_INT
@@ -1864,7 +1865,6 @@ compute_record_mode (tree type)
 		       (pack_cumulative_args (0),
 			function_arg_info (type, mode, /*named=*/false)))))))
       && mode != VOIDmode
-      && poly_int_tree_p (TYPE_SIZE (type), &type_size)
       && known_eq (GET_MODE_BITSIZE (mode), type_size))
     ;
   else