stor-layout.c (compute_record_mode): Don't force BLKmode if field is zero-length BLKmode.

	* stor-layout.c (compute_record_mode): Don't force BLKmode if
	field is zero-length BLKmode.
	* expr.c (expand_expr, case COMPONENT_REF): Handle case of BLKmode
	zero-size references.

From-SVN: r72311

gcc/ChangeLog

 2003-10-10  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 
+	* stor-layout.c (compute_record_mode): Don't force BLKmode if
+	field is zero-length BLKmode.
+	* expr.c (expand_expr, case COMPONENT_REF): Handle case of BLKmode
+	zero-size references.
+
 	* combine.c (distribute_links): Properly test for REG being set.
 
 	* config/alpha/alpha.c (alpha_expand_block_mode): Don't use

gcc/expr.c

@@ -7223,6 +7223,12 @@ expand_expr (tree exp, rtx target, enum machine_mode tmode,
 
 	    if (ext_mode == BLKmode)
 	      {
+		if (target == 0)
+		  target = assign_temp (type, 0, 1, 1);
+
+		if (bitsize == 0)
+		  return target;
+
 		/* In this case, BITPOS must start at a byte boundary and
 		   TARGET, if specified, must be a MEM.  */
 		if (GET_CODE (op0) != MEM
@@ -7230,11 +7236,9 @@ expand_expr (tree exp, rtx target, enum machine_mode tmode,
 		    || bitpos % BITS_PER_UNIT != 0)
 		  abort ();
 
-		op0 = adjust_address (op0, VOIDmode, bitpos / BITS_PER_UNIT);
-		if (target == 0)
-		  target = assign_temp (type, 0, 1, 1);
-
-		emit_block_move (target, op0,
+		emit_block_move (target,
+				 adjust_address (op0, VOIDmode,
+						 bitpos / BITS_PER_UNIT),
 				 GEN_INT ((bitsize + BITS_PER_UNIT - 1)
 					  / BITS_PER_UNIT),
 				 (modifier == EXPAND_STACK_PARM

gcc/stor-layout.c

@@ -1318,7 +1318,9 @@ compute_record_mode (tree type)
 
       if (TREE_CODE (TREE_TYPE (field)) == ERROR_MARK
 	  || (TYPE_MODE (TREE_TYPE (field)) == BLKmode
-	      && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field)))
+	      && ! TYPE_NO_FORCE_BLK (TREE_TYPE (field))
+	      && !(TYPE_SIZE (TREE_TYPE (field)) != 0
+		   && integer_zerop (TYPE_SIZE (TREE_TYPE (field)))))
 	  || ! host_integerp (bit_position (field), 1)
 	  || DECL_SIZE (field) == 0
 	  || ! host_integerp (DECL_SIZE (field), 1))