[32/77] Check is_a <scalar_int_mode> before calling valid_pointer_mode

A future patch will make valid_pointer_mode take a scalar_int_mode
instead of a machine_mode.  is_a <...> rather than as_a <...> is
needed here because we're checking a mode supplied by the user.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/c-family/
	* c-attribs.c (handle_mode_attribute): Check for a scalar_int_mode
	before calling targetm.addr_space.valid_pointer_mode.

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

From-SVN: r251484

gcc/c-family/ChangeLog

@@ -2,6 +2,13 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* c-attribs.c (handle_mode_attribute): Check for a scalar_int_mode
+	before calling targetm.addr_space.valid_pointer_mode.
+
+2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* c-cppbuiltin.c (c_cpp_builtins): Use opt_scalar_float_mode.
 
 2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/c-family/c-attribs.c

@@ -1469,10 +1469,12 @@ handle_mode_attribute (tree *node, tree name, tree args,
 
       if (POINTER_TYPE_P (type))
 	{
+	  scalar_int_mode addr_mode;
 	  addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (type));
 	  tree (*fn)(tree, machine_mode, bool);
 
-	  if (!targetm.addr_space.valid_pointer_mode (mode, as))
+	  if (!is_a <scalar_int_mode> (mode, &addr_mode)
+	      || !targetm.addr_space.valid_pointer_mode (addr_mode, as))
 	    {
 	      error ("invalid pointer mode %qs", p);
 	      return NULL_TREE;
@@ -1482,7 +1484,7 @@ handle_mode_attribute (tree *node, tree name, tree args,
 	    fn = build_pointer_type_for_mode;
 	  else
 	    fn = build_reference_type_for_mode;
-	  typefm = fn (TREE_TYPE (type), mode, false);
+	  typefm = fn (TREE_TYPE (type), addr_mode, false);
 	}
       else
 	{