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
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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
+inte
