calls.c (expand_call): Strip a TARGET_EXPR if we're passing by invisible reference.

	* calls.c (expand_call): Strip a TARGET_EXPR if we're passing by
	invisible reference.

From-SVN: r24763

gcc/ChangeLog

+Tue Jan 19 11:54:04 1999  Jason Merrill  <jason@yorick.cygnus.com>
+
+	* calls.c (expand_call): Strip a TARGET_EXPR if we're passing by
+	invisible reference.
+
 Tue Jan 19 14:51:36 1999  David Edelsohn  <edelsohn@mhpcc.edu>
 
 	* rs6000.c (offsettable_addr_operand): Delete.

gcc/calls.c

@@ -1345,6 +1345,22 @@ expand_call (exp, target, ignore)
 #endif
 	      )
 	    {
+	      /* C++ uses a TARGET_EXPR to indicate that we want to make a
+	         new object from the argument.  If we are passing by
+	         invisible reference, the callee will do that for us, so we
+	         can strip off the TARGET_EXPR.  This is not always safe,
+	         but it is safe in the only case where this is a useful
+	         optimization; namely, when the argument is a plain object.
+	         In that case, the frontend is just asking the backend to
+	         make a bitwise copy of the argument. */
+		 
+	      if (TREE_CODE (args[i].tree_value) == TARGET_EXPR
+		  && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND
+						  (args[i].tree_value, 1)))
+		      == 'd')
+		  && ! REG_P (DECL_RTL (TREE_OPERAND (args[i].tree_value, 1))))
+		args[i].tree_value = TREE_OPERAND (args[i].tree_value, 1);
+
 	      args[i].tree_value = build1 (ADDR_EXPR,
 					   build_pointer_type (type),
 					   args[i].tree_value);