incorrect composite_type result for pointers with mode

[Tristan Gingold]

Hi,

composite_type doesn't consider the pointer mode when creating a pointer.
As a consequence:

type char *p32 __attribute__((mode (SI));
type char *p32 __attribute__((mode (SI));

creates a 64-bit pointers (on ia64-hp-openvms and certainly some other 
configuration).
This breaks some compiler builds (depending on the build options).

As far as I know, this is not a regression, so it may not qualify for a stage 4 
submission.

Tristan.

2012-01-25  Tristan Gingold  <ging...@adacore.com>

        * c-typeck.c (composite_type): Keep mode for pointers.

diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index b696e5e..2e33763 100644
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -394,7 +394,7 @@ composite_type (tree t1, tree t2)
        tree pointed_to_1 = TREE_TYPE (t1);
        tree pointed_to_2 = TREE_TYPE (t2);
        tree target = composite_type (pointed_to_1, pointed_to_2);
-       t1 = build_pointer_type (target);
+       t1 = build_pointer_type_for_mode (target, TYPE_MODE (t1), false);
        t1 = build_type_attribute_variant (t1, attributes);
        return qualify_type (t1, t2);
       }