stor-layout.c (layout_type): Handle arrays of bits, for Chill.

Mon Jul 27 17:18:52 1998  Dave Brolley  <brolley@cygnus.com>
	* stor-layout.c (layout_type): Handle arrays of bits, for Chill.
	* expr.c (get_inner_reference): Handle zero-based, unsigned, array
	index conversion.

From-SVN: r21416

gcc/ChangeLog

+Mon Jul 27 17:18:52 1998  Dave Brolley  <brolley@cygnus.com>
+
+	* stor-layout.c (layout_type): Handle arrays of bits, for Chill.
+
+	* expr.c (get_inner_reference): Handle zero-based, unsigned, array
+	index conversion.
+
 Mon Jul 27 14:51:33 1998  Jeffrey A Law  (law@cygnus.com)
 
 	* mn10300.h (DEBUGGER_AUTO_OFFSET): Define.

gcc/expr.c

@@ -4546,8 +4546,20 @@ get_inner_reference (exp, pbitsize, pbitpos, poffset, pmode,
 	      index_type = TREE_TYPE (index);
 	    }
 
+	  /* Optimize the special-case of a zero lower bound.
+	     
+	     We convert the low_bound to sizetype to avoid some problems
+	     with constant folding.  (E.g. suppose the lower bound is 1,
+	     and its mode is QI.  Without the conversion,  (ARRAY
+	     +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
+	     +INDEX), which becomes (ARRAY+255+INDEX).  Oops!)
+	     
+	     But sizetype isn't quite right either (especially if
+	     the lowbound is negative).  FIXME */
+
 	  if (! integer_zerop (low_bound))
-	    index = fold (build (MINUS_EXPR, index_type, index, low_bound));
+	    index = fold (build (MINUS_EXPR, index_type, index,
+				 convert (sizetype, low_bound)));
 
 	  if (TREE_CODE (index) == INTEGER_CST)
 	    {

gcc/stor-layout.c

@@ -783,6 +783,7 @@ layout_type (type)
 	    tree ub = TYPE_MAX_VALUE (index);
 	    tree lb = TYPE_MIN_VALUE (index);
 	    tree length;
+	    tree element_size;
 
 	    /* If UB is max (lb - 1, x), remove the MAX_EXPR since the
 	       test for negative below covers it.  */
@@ -815,8 +816,19 @@ layout_type (type)
 		&& TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
 	      length = size_binop (MAX_EXPR, length, size_zero_node);
 
-	    TYPE_SIZE (type) = size_binop (MULT_EXPR, TYPE_SIZE (element),
-					   length);
+	    /* Special handling for arrays of bits (for Chill).  */
+	    element_size = TYPE_SIZE (element);
+	    if (TYPE_PACKED (type) && INTEGRAL_TYPE_P (element))
+	      {
+		HOST_WIDE_INT maxvalue, minvalue;
+		maxvalue = TREE_INT_CST_LOW (TYPE_MAX_VALUE (element));
+		minvalue = TREE_INT_CST_LOW (TYPE_MIN_VALUE (element));
+		if (maxvalue - minvalue == 1
+		    && (maxvalue == 1 || maxvalue == 0))
+		  element_size = integer_one_node;
+	      }
+
+	    TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size, length);
 
 	    /* If we know the size of the element, calculate the total
 	       size directly, rather than do some division thing below.