[Bug tree-optimization/66768] address space gets lost on literal pointer

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66768

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Target|                            |avr
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-07-07
            Version|unknown                     |6.0
            Summary|__seg_fs and __seg_gs:      |address space gets lost on
                   |issue when adding address   |literal pointer
                   |space support               |
     Ever confirmed|0                           |1

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
IVOPTs seems to carry address-space info on 'type' here (in fact if I amend
tree dumping with address-space dumping on memory references I fail to get
proper address-space info on the first function _before_ IVOPTs...).

Address-space info is on the base object type, not on the type of the
memory reference (for MEM_REF and TARGET_MEM_REF, that is).

For the IVOPTs issue a way to fix the particular testcase is

Index: gcc/tree-ssa-address.c
===================================================================
--- gcc/tree-ssa-address.c      (revision 225504)
+++ gcc/tree-ssa-address.c      (working copy)
@@ -395,7 +395,7 @@ create_mem_ref_raw (tree type, tree alia
     }
   else
     {
-      base = build_int_cst (ptr_type_node, 0);
+      base = build_int_cst (build_pointer_type (type), 0);
       index2 = addr->base;
     }

but then we ICE in convert_memory_address_addr_space_1

#1  0x000000000093323b in convert_memory_address_addr_space_1 (
    to_mode=PSImode, x=0x7ffff69f5c60, as=7 '\a', in_const=false)
    at /space/rguenther/tramp3d/trunk/gcc/explow.c:282
282       gcc_assert (GET_MODE (x) == to_mode || GET_MODE (x) == VOIDmode);
(gdb) p debug_rtx (x)
(subreg:HI (reg:PSI 42 [ ivtmp.21 ]) 0)

at least the address-space is now on the MEM_REF:

  <bb 3>:
  # total_11 = PHI <total_5(3), 0(2)>
  # ivtmp.21_2 = PHI <ivtmp.21_7(3), 4660(2)>
  _12 = (sizetype) ivtmp.21_2;
  _4 = MEM[base: 0B, index: _12, offset: 0B]<address-space-7> ;

the ICE is probably a AVR bug (it's inside POITNERS_EXTEND_UNSIGNED).
Possibly the subreg case can be applied for POINTERS_EXTEND_UNSIGNED as well.