Hi,
This patch adds the OpenMP runtime routine "omp_target_is_accessible" which was
introduced in OpenMP 5.1 (specification section 3.8.4):
"The omp_target_is_accessible routine tests whether host memory is accessible
from a given device."
"This routine returns true if the storage of size bytes starting at the address
given by ptr is accessible from device device_num. Otherwise, it returns false."
"The value of ptr must be a valid host pointer or NULL (or C_NULL_PTR, for
Fortran). The device_num argument must be greater than or equal to zero and less
than or equal to the result of omp_get_num_devices()."
"When called from within a target region the effect is unspecified."
Currently, the only way of accessing host memory on a non-host device is via
shared memory. This will change with unified shared memory (usm) that was
recently submitted but not yet approved/committed. A follow-up patch for
omp_target_is_accessible is planned considering usm when available. The current
patch handles the basic implementation for C/C++ and Fortran and includes
comments pointing to usm.
Although not explicitly specified in the OpenMP 5.1 standard, the implemented
function returns "true" if the given device_num is equal to
"omp_get_num_devices" (i.e. the host) as it is expected that host memory can be
accessed from the host device.
The patch was tested on x86_64-linux and PowerPC, both with nvptx offloading.
All with no regressions.
Marcel
-----------------
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634
München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas
Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht
München, HRB 106955
OpenMP, libgomp: Add new runtime routine omp_target_is_accessible.
gcc/ChangeLog:
* omp-low.cc (omp_runtime_api_call): Added target_is_accessible to
omp_runtime_apis array.
libgomp/ChangeLog:
* libgomp.map: Added omp_target_is_accessible.
* libgomp.texi: Tagged omp_target_is_accessible as supported.
* omp.h.in: Added omp_target_is_accessible.
* omp_lib.f90.in: Added interface for omp_target_is_accessible.
* omp_lib.h.in: Likewise.
* target.c (omp_target_is_accessible): Added implementation of
omp_target_is_accessible.
* testsuite/libgomp.c-c++-common/target-is-accessible-1.c: New test.
* testsuite/libgomp.fortran/target-is-accessible-1.f90: New test.
diff --git a/gcc/omp-low.cc b/gcc/omp-low.cc
index 77176ef..bf38fad 100644
--- a/gcc/omp-low.cc
+++ b/gcc/omp-low.cc
@@ -3959,6 +3959,7 @@ omp_runtime_api_call (const_tree fndecl)
"target_associate_ptr",
"target_disassociate_ptr",
"target_free",
+ "target_is_accessible",
"target_is_present",
"target_memcpy",
"target_memcpy_rect",
diff --git a/libgomp/libgomp.map b/libgomp/libgomp.map
index 2ac5809..1764380 100644
--- a/libgomp/libgomp.map
+++ b/libgomp/libgomp.map
@@ -226,6 +226,11 @@ OMP_5.1 {
omp_get_teams_thread_limit_;
} OMP_5.0.2;
+OMP_5.1.1 {
+ global:
+ omp_target_is_accessible;
+} OMP_5.1;
+
GOMP_1.0 {
global:
GOMP_atomic_end;
diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
index 161a423..58e432c 100644
--- a/libgomp/libgomp.texi
+++ b/libgomp/libgomp.texi
@@ -311,7 +311,7 @@ The OpenMP 4.5 specification is fully supported.
@item @code{omp_set_num_teams}, @code{omp_set_teams_thread_limit},
@code{omp_get_max_teams}, @code{omp_get_teams_thread_limit} runtime
routines @tab Y @tab
-@item @code{omp_target_is_accessible} runtime routine @tab N @tab
+@item @code{omp_target_is_accessible} runtime routine @tab Y @tab
@item @code{omp_target_memcpy_async} and @code{omp_target_memcpy_rect_async}
runtime routines @tab N @tab
@item @code{omp_get_mapped_ptr} runtime routine @tab N @tab
diff --git a/libgomp/omp.h.in b/libgomp/omp.h.in
index 89c5d65..1ec7415 100644
--- a/libgomp/omp.h.in
+++ b/libgomp/omp.h.in
@@ -282,6 +282,8 @@ extern int omp_target_memcpy_rect (void *, const void *,
__SIZE_TYPE__, int,
extern int omp_target_associate_ptr (const void *, const void *, __SIZE_TYPE__,
__SIZE_TYPE__, int) __GOMP_NOTHROW;
extern int omp_target_disassociate_ptr (const void *, int) __GOMP_NOTHROW;
+extern int omp_target_is_accessible (const void *, __SIZE_TYPE__, int)
+ __GOMP_NOTHROW;
extern void omp_set_affinity_format (const char *) __GOMP_NOTHROW;
extern __SIZE_TYPE__ omp_get_affinity_format (char *, __SIZE_TYPE__)
diff --git a/libgomp/omp_lib.f90.in b/libgomp/omp_lib.f90.in
index daf40dc..f369507 100644
--- a/libgomp/omp_lib.f90.in
+++ b/libgomp/omp_lib.f90.in
@@ -835,6 +835,16 @@
end function omp_target_disassociate_ptr
end interface
+ interface
+ function omp_target_is_accessible (ptr, size, device_num) bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_size_t, c_int
+ integer(c_int) :: omp_target_is_accessible
+ type(c_ptr), value :: ptr
+ integer(c_size_t), value :: size
+ integer(c_int), value :: device_num
+ end function omp_target_is_accessible
+ end interface
+
#if _OPENMP >= 201811
!GCC$ ATTRIBUTES DEPRECATED :: omp_get_nested, omp_set_nested
#endif
diff --git a/libgomp/omp_lib.h.in b/libgomp/omp_lib.h.in
index ff857a4..5ea0366 100644
--- a/libgomp/omp_lib.h.in
+++ b/libgomp/omp_lib.h.in
@@ -416,3 +416,14 @@
integer(c_int), value :: device_num
end function omp_target_disassociate_ptr
end interface
+
+ interface
+ function omp_target_is_accessible (ptr, size, device_num) &
+ & bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_size_t, c_int
+ integer(c_int) :: omp_target_is_accessible
+ type(c_ptr), value :: ptr
+ integer(c_size_t), value :: size
+ integer(c_int), value :: device_num
+ end function omp_target_is_accessible
+ end interface
diff --git a/libgomp/target.c b/libgomp/target.c
index 9017458..01d36d1 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -3666,6 +3666,24 @@ omp_target_disassociate_ptr (const void *ptr, int
device_num)
}
int
+omp_target_is_accessible (const void *ptr, size_t size, int device_num)
+{
+ if (device_num < 0 || device_num > gomp_get_num_devices ())
+ return false;
+
+ if (device_num == gomp_get_num_devices ())
+ return true;
+
+ struct gomp_device_descr *devicep = resolve_device (device_num);
+ if (devicep == NULL)
+ return false;
+
+ /* TODO: Unified shared memory must be handled when available. */
+
+ return devicep->capabilities & GOMP_OFFLOAD_CAP_SHARED_MEM;
+}
+
+int
omp_pause_resource (omp_pause_resource_t kind, int device_num)
{
(void) kind;
diff --git a/libgomp/testsuite/libgomp.c-c++-common/target-is-accessible-1.c
b/libgomp/testsuite/libgomp.c-c++-common/target-is-accessible-1.c
new file mode 100644
index 0000000..6788894
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/target-is-accessible-1.c
@@ -0,0 +1,42 @@
+#include <omp.h>
+
+int
+main ()
+{
+ int d = omp_get_default_device ();
+ int id = omp_get_initial_device ();
+ int n = omp_get_num_devices ();
+ void *p;
+
+ if (d < 0 || d >= n)
+ d = id;
+
+ if (!omp_target_is_accessible (p, sizeof (int), n))
+ __builtin_abort ();
+
+ if (!omp_target_is_accessible (p, sizeof (int), id))
+ __builtin_abort ();
+
+ if (omp_target_is_accessible (p, sizeof (int), -1))
+ __builtin_abort ();
+
+ if (omp_target_is_accessible (p, sizeof (int), n + 1))
+ __builtin_abort ();
+
+ /* Currently, a host pointer is accessible if the device supports shared
+ memory or omp_target_is_accessible is executed on the host. This
+ test case must be adapted when unified shared memory is avialable. */
+ int shared_mem = 0;
+ #pragma omp target map (alloc: shared_mem) device (d)
+ shared_mem = 1;
+ if (omp_target_is_accessible (p, sizeof (int), d) != shared_mem)
+ __builtin_abort ();
+
+ int a[128];
+ p = &a;
+ for (int i = 0; i < 128; i++)
+ if (omp_target_is_accessible (p, 128 * sizeof (int), d) != shared_mem)
+ __builtin_abort ();
+
+ return 0;
+}
diff --git a/libgomp/testsuite/libgomp.fortran/target-is-accessible-1.f90
b/libgomp/testsuite/libgomp.fortran/target-is-accessible-1.f90
new file mode 100644
index 0000000..eae696f
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/target-is-accessible-1.f90
@@ -0,0 +1,44 @@
+program main
+ use omp_lib
+ use iso_c_binding
+ implicit none (external, type)
+ integer :: d, id, n, shared_mem, i
+ integer, target :: a(1:128)
+ type(c_ptr) :: p
+
+ d = omp_get_default_device ()
+ id = omp_get_initial_device ()
+ n = omp_get_num_devices ()
+
+ if (d < 0 .or. d >= n) &
+ d = id
+
+ if (omp_target_is_accessible (p, c_sizeof (d), n) /= 1) &
+ stop 1
+
+ if (omp_target_is_accessible (p, c_sizeof (d), id) /= 1) &
+ stop 2
+
+ if (omp_target_is_accessible (p, c_sizeof (d), -1) /= 0) &
+ stop 3
+
+ if (omp_target_is_accessible (p, c_sizeof (d), n + 1) /= 0) &
+ stop 4
+
+ ! Currently, a host pointer is accessible if the device supports shared
+ ! memory or omp_target_is_accessible is executed on the host. This
+ ! test case must be adapted when unified shared memory is avialable.
+ shared_mem = 0;
+ !$omp target map (alloc: shared_mem) device (d)
+ shared_mem = 1;
+ !$omp end target
+ if (omp_target_is_accessible (p, c_sizeof (d), d) /= shared_mem) &
+ stop 5;
+
+ p = c_loc (a)
+ do i = 1, 128
+ if (omp_target_is_accessible (p, 128 * sizeof (d), d) /= shared_mem) &
+ stop 6;
+ end do
+
+end program main
