[committed][OG12] libgomp: no need to attach USM pointers

[Andrew Stubbs]

This patch fixes a bug in which libgomp doesn't know what to do with 
attached pointers in fortran derived types when using Unified Shared 
Memory instead of explicit mappings.

I've committed it to the devel/omp/gcc-12 branch (OG12) and will fold it 
into the next rebase/repost of the USM patches.

Andrewlibgomp: no need to attach USM pointers

Fix a bug in which Fortran pointers inside derived types caused a runtime
error when Unified Shared Memory was active.

libgomp/ChangeLog:

        * target.c (gomp_attach_pointer): Check for USM.
        * testsuite/libgomp.fortran/usm-3.f90: New test.

diff --git a/libgomp/target.c b/libgomp/target.c
index 24109f28ddc..fcc5b9dabca 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -836,6 +836,11 @@ gomp_attach_pointer (struct gomp_device_descr *devicep,
          gomp_fatal ("attempt to attach null pointer");
        }
 
+      if (devicep->is_usm_ptr_func
+         && devicep->is_usm_ptr_func ((void*)(target + bias)))
+       /* Nothing to do here.  */
+       return;
+
       s.host_start = target + bias;
       s.host_end = s.host_start + 1;
       tn = splay_tree_lookup (mem_map, &s);
diff --git a/libgomp/testsuite/libgomp.fortran/usm-3.f90 
b/libgomp/testsuite/libgomp.fortran/usm-3.f90
new file mode 100644
index 00000000000..ff15f4ba1f5
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/usm-3.f90
@@ -0,0 +1,33 @@
+! { dg-do run }
+! { dg-require-effective-target omp_usm }
+
+! Ensure that derived types containing allocated values work
+! with Unified Shared Memory.
+
+program usm
+!$omp requires unified_shared_memory
+  use iso_fortran_env
+  implicit none
+
+  type :: struct
+    real(real64), allocatable :: v(:)
+  end type struct
+
+  integer :: index
+  type(struct) :: s
+
+  real(real64), allocatable :: expected(:)
+
+  allocate(s%v(100))
+  do index = 1, size(s%v)
+    s%v(index) = index
+  end do
+  allocate(expected, mold=s%v)
+  expected = s%v - 1._real64
+
+  !$omp target
+  s%v = s%v - 1._real64
+  !$omp end target
+
+  if (any(s%v /= expected)) STOP 1
+end program usm