On 12/02/15 13:10:44, Richard Guenther wrote: > On Tue, Dec 1, 2015 at 7:02 AM, Gary Funck <g...@intrepid.com> wrote: > > UPC pointers-to-shared have an internal representation which is > > defined as a 'struct' with three fields. Special logic is > > needed in promote_mode() to handle this case. > > Errr - but how are 'struct's ever REFERENCE_TYPE or POINTER_TYPE?
UPC pointers-to-shared types are pointer types, but they typically have a mode that is 2x the size of the normal pointer mode. Currently, 'upc_pts_type_node' is a global tree mode that describes the internal representation of a UPC pointer-to-shared. The code shown below takes the mode of 'upc_pts_type_node' (TIMode, typically on 64 bit targets) and returns that. As noted in an earlier reply, this mode could be saved in a global somewhere (similar to pointer_mode) which could be used to avoid the reference to 'upc_pts_type_node' below. > > +++ gcc/explow.c (.../branches/gupc) (revision 231080) > > @@ -794,6 +794,8 @@ promote_mode (const_tree type ATTRIBUTE_ > > case REFERENCE_TYPE: > > case POINTER_TYPE: > > *punsignedp = POINTERS_EXTEND_UNSIGNED; > > + if (SHARED_TYPE_P (TREE_TYPE (type))) > > + return TYPE_MODE (upc_pts_type_node); > > return targetm.addr_space.address_mode > > (TYPE_ADDR_SPACE (TREE_TYPE (type))); > > break; Asked in previous email: Can an address space be used for UPC pointers-to-shared? Yes, if TIMode were allowed, for example (on 64-bit targets), and that was the mode associated with th special UPC reserved address space number, it would take care of returning the proper mode for UPC pointers-to-shared types. Address spaces are insufficient however to handle the situations where the semantics of pointer arithmetic for UPC pointers-to-shared differs from those of regular "C" pointers, or for conversions, and situations where optimizations of operations involving "C" pointers do not apply to "UPC" shared pointers. So, we can't just dedicate an address space for UPC pointers-to-shared and be done with it. thanks, - Gary
