[OpenMP] Implement omp_get_uid_from_device() / omp_get_device_from_uid() #164392

ro-i · 2025-10-21T10:41:12Z

Use the implementation in libomptarget. If libomptarget is not available, always return the UID / device number of the host / the initial device.

llvmbot · 2025-10-21T10:41:56Z

@llvm/pr-subscribers-offload

Author: Robert Imschweiler (ro-i)

Changes

Use the implementation in libomptarget. If libomptarget is not available, always return the UID / device number of the host / the initial device.

Full diff: https://github.com/llvm/llvm-project/pull/164392.diff

15 Files Affected:

(modified) offload/include/OpenMP/omp.h (+7)
(modified) offload/include/omptarget.h (+2)
(modified) offload/libomptarget/OpenMP/API.cpp (+55)
(modified) offload/libomptarget/exports (+2)
(added) offload/test/api/omp_device_uid.c (+88)
(modified) openmp/device/include/DeviceTypes.h (+2)
(modified) openmp/device/include/Interface.h (+4)
(modified) openmp/device/src/State.cpp (+6)
(modified) openmp/runtime/src/dllexports (+2)
(modified) openmp/runtime/src/include/omp.h.var (+5)
(modified) openmp/runtime/src/include/omp_lib.F90.var (+14)
(modified) openmp/runtime/src/include/omp_lib.h.var (+19)
(modified) openmp/runtime/src/kmp_ftn_entry.h (+14-2)
(modified) openmp/runtime/src/kmp_ftn_os.h (+8)
(added) openmp/runtime/test/api/omp_device_uid.c (+89)

diff --git a/offload/include/OpenMP/omp.h b/offload/include/OpenMP/omp.h
index 49d9f1fa75c20..a42724f87cf3a 100644
--- a/offload/include/OpenMP/omp.h
+++ b/offload/include/OpenMP/omp.h
@@ -30,6 +30,13 @@
 
 extern "C" {
 
+/// Definitions
+///{
+
+#define omp_invalid_device -2
+
+///}
+
 /// Type declarations
 ///{
 
diff --git a/offload/include/omptarget.h b/offload/include/omptarget.h
index 794b79e07674e..332b0d9f5cf27 100644
--- a/offload/include/omptarget.h
+++ b/offload/include/omptarget.h
@@ -274,6 +274,8 @@ extern "C" {
 void ompx_dump_mapping_tables(void);
 int omp_get_num_devices(void);
 int omp_get_device_num(void);
+int omp_get_device_from_uid(const char *DeviceUid);
+const char *omp_get_uid_from_device(int DeviceNum);
 int omp_get_initial_device(void);
 void *omp_target_alloc(size_t Size, int DeviceNum);
 void omp_target_free(void *DevicePtr, int DeviceNum);
diff --git a/offload/libomptarget/OpenMP/API.cpp b/offload/libomptarget/OpenMP/API.cpp
index b0f0573833713..cc4b607ccee6d 100644
--- a/offload/libomptarget/OpenMP/API.cpp
+++ b/offload/libomptarget/OpenMP/API.cpp
@@ -40,6 +40,8 @@ EXTERN void ompx_dump_mapping_tables() {
 using namespace llvm::omp::target::ompt;
 #endif
 
+using GenericDeviceTy = llvm::omp::target::plugin::GenericDeviceTy;
+
 void *targetAllocExplicit(size_t Size, int DeviceNum, int Kind,
                           const char *Name);
 void targetFreeExplicit(void *DevicePtr, int DeviceNum, int Kind,
@@ -91,6 +93,59 @@ EXTERN int omp_get_device_num(void) {
   return HostDevice;
 }
 
+EXTERN int omp_get_device_from_uid(const char *DeviceUid) {
+  TIMESCOPE();
+  OMPT_IF_BUILT(ReturnAddressSetterRAII RA(__builtin_return_address(0)));
+
+  if (!DeviceUid) {
+    DP("Call to omp_get_device_from_uid returning omp_invalid_device\n");
+    return omp_invalid_device;
+  }
+  if (strcmp(DeviceUid, GenericDeviceTy::getHostDeviceUid()) == 0) {
+    DP("Call to omp_get_device_from_uid returning host device number %d\n",
+       omp_get_initial_device());
+    return omp_get_initial_device();
+  }
+
+  int DeviceNum = omp_invalid_device;
+
+  auto ExclusiveDevicesAccessor = PM->getExclusiveDevicesAccessor();
+  for (const DeviceTy &Device : PM->devices(ExclusiveDevicesAccessor)) {
+    const char *Uid = Device.RTL->getDevice(Device.RTLDeviceID).getDeviceUid();
+    if (Uid && strcmp(DeviceUid, Uid) == 0) {
+      DeviceNum = Device.DeviceID;
+      break;
+    }
+  }
+
+  DP("Call to omp_get_device_from_uid returning %d\n", DeviceNum);
+  return DeviceNum;
+}
+
+EXTERN const char *omp_get_uid_from_device(int DeviceNum) {
+  TIMESCOPE();
+  OMPT_IF_BUILT(ReturnAddressSetterRAII RA(__builtin_return_address(0)));
+
+  if (DeviceNum == omp_invalid_device) {
+    DP("Call to omp_get_uid_from_device returning nullptr\n");
+    return nullptr;
+  }
+  if (DeviceNum == omp_get_initial_device()) {
+    DP("Call to omp_get_uid_from_device returning host device UID\n");
+    return GenericDeviceTy::getHostDeviceUid();
+  }
+
+  llvm::Expected<DeviceTy &> Device = PM->getDevice(DeviceNum);
+  if (!Device) {
+    FATAL_MESSAGE(DeviceNum, "%s", toString(Device.takeError()).c_str());
+    return nullptr;
+  }
+
+  const char *Uid = Device->RTL->getDevice(Device->RTLDeviceID).getDeviceUid();
+  DP("Call to omp_get_uid_from_device returning %s\n", Uid);
+  return Uid;
+}
+
 EXTERN int omp_get_initial_device(void) {
   TIMESCOPE();
   OMPT_IF_BUILT(ReturnAddressSetterRAII RA(__builtin_return_address(0)));
diff --git a/offload/libomptarget/exports b/offload/libomptarget/exports
index 1374bfea81511..f8fffb085a5dc 100644
--- a/offload/libomptarget/exports
+++ b/offload/libomptarget/exports
@@ -40,6 +40,8 @@ VERS1.0 {
     omp_get_mapped_ptr;
     omp_get_num_devices;
     omp_get_device_num;
+    omp_get_device_from_uid;
+    omp_get_uid_from_device;
     omp_get_initial_device;
     omp_target_alloc;
     omp_target_free;
diff --git a/offload/test/api/omp_device_uid.c b/offload/test/api/omp_device_uid.c
new file mode 100644
index 0000000000000..e07da8e56da98
--- /dev/null
+++ b/offload/test/api/omp_device_uid.c
@@ -0,0 +1,88 @@
+// RUN: %libomptarget-compile-run-and-check-generic
+
+#include <omp.h>
+#include <stdio.h>
+#include <string.h>
+
+// Note that the device UIDs for the "fake" host devices used by libomptarget
+// will always be the same as the UID for the initial device (since it *is* the
+// same device).  The other way round, the device number returned for this UID
+// will always be the initial device.
+
+int is_host_device_uid(const char *device_uid) {
+  return strcmp(device_uid,
+                omp_get_uid_from_device(omp_get_initial_device())) == 0;
+}
+
+int test_omp_device_uid(int device_num) {
+  const char *device_uid = omp_get_uid_from_device(device_num);
+  if (device_uid == NULL) {
+    printf("FAIL for device %d: omp_get_uid_from_device returned NULL\n",
+           device_num);
+    return 0;
+  }
+
+  int device_num_from_uid = omp_get_device_from_uid(device_uid);
+  if (device_num_from_uid != (is_host_device_uid(device_uid)
+                                  ? omp_get_initial_device()
+                                  : device_num)) {
+    printf(
+        "FAIL for device %d: omp_get_device_from_uid returned %d (UID: %s)\n",
+        device_num, device_num_from_uid, device_uid);
+    return 0;
+  }
+
+  if (device_num == omp_get_initial_device())
+    return 1;
+
+  int success = 1;
+
+// Note that the following code may be executed on the host if the host is the
+// device
+#pragma omp target map(tofrom : success) device(device_num)
+  {
+    int device_num = omp_get_device_num();
+
+    // omp_get_uid_from_device() in the device runtime is a dummy function
+    // returning NULL
+    const char *device_uid_target = omp_get_uid_from_device(device_num);
+
+    // omp_get_device_from_uid() in the device runtime is a dummy function
+    // returning omp_invalid_device.
+    device_num_from_uid = omp_get_device_from_uid(device_uid_target);
+
+    // Depending on whether we're executing on the device or the host, we either
+    // got NULL as the device UID or the correct device UID.  Consequently,
+    // omp_get_device_from_uid() either returned omp_invalid_device or the
+    // correct device number (aka omp_get_initial_device()).
+    if (device_uid_target ? device_num_from_uid != omp_get_initial_device()
+                          : device_num_from_uid != omp_invalid_device) {
+      printf("FAIL for device %d (target): omp_get_device_from_uid returned %d "
+             "(UID: %s)\n",
+             device_num, device_num_from_uid, device_uid_target);
+      success = 0;
+    }
+  }
+
+  return success;
+}
+
+int main() {
+  int num_devices = omp_get_num_devices();
+  int num_failed = 0;
+  // (also test initial device aka num_devices)
+  for (int i = 0; i < num_devices + 1; i++) {
+    if (!test_omp_device_uid(i)) {
+      printf("FAIL for device %d\n", i);
+      num_failed++;
+    }
+  }
+  if (num_failed) {
+    printf("FAIL\n");
+    return 1;
+  }
+  printf("PASS\n");
+  return 0;
+}
+
+// CHECK: PASS
diff --git a/openmp/device/include/DeviceTypes.h b/openmp/device/include/DeviceTypes.h
index 2e5d92380f040..b7f9c5fe7b7cd 100644
--- a/openmp/device/include/DeviceTypes.h
+++ b/openmp/device/include/DeviceTypes.h
@@ -21,6 +21,8 @@ template <typename T> using Constant = __gpu_constant T;
 template <typename T> using Local = __gpu_local T;
 template <typename T> using Global = __gpu_local T;
 
+#define omp_invalid_device -2
+
 enum omp_proc_bind_t {
   omp_proc_bind_false = 0,
   omp_proc_bind_true = 1,
diff --git a/openmp/device/include/Interface.h b/openmp/device/include/Interface.h
index c4bfaaa2404b4..71c3b1fc06d40 100644
--- a/openmp/device/include/Interface.h
+++ b/openmp/device/include/Interface.h
@@ -130,6 +130,10 @@ int omp_get_num_devices(void);
 
 int omp_get_device_num(void);
 
+int omp_get_device_from_uid(const char *DeviceUid);
+
+const char *omp_get_uid_from_device(int DeviceNum);
+
 int omp_get_num_teams(void);
 
 int omp_get_team_num();
diff --git a/openmp/device/src/State.cpp b/openmp/device/src/State.cpp
index 475395102f47b..8ccb9d2ca24ff 100644
--- a/openmp/device/src/State.cpp
+++ b/openmp/device/src/State.cpp
@@ -423,6 +423,12 @@ int omp_get_num_devices(void) { return config::getNumDevices(); }
 
 int omp_get_device_num(void) { return config::getDeviceNum(); }
 
+int omp_get_device_from_uid(const char *DeviceUid) {
+  return omp_invalid_device;
+}
+
+const char *omp_get_uid_from_device(int DeviceNum) { return nullptr; }
+
 int omp_get_num_teams(void) { return mapping::getNumberOfBlocksInKernel(); }
 
 int omp_get_team_num() { return mapping::getBlockIdInKernel(); }
diff --git a/openmp/runtime/src/dllexports b/openmp/runtime/src/dllexports
index 3983dae80c9f5..00becd1a657fd 100644
--- a/openmp/runtime/src/dllexports
+++ b/openmp/runtime/src/dllexports
@@ -544,6 +544,8 @@ kmp_set_disp_num_buffers                    890
     omp_get_devices_all_allocator           819
     omp_get_memspace_num_resources          820
     omp_get_submemspace                     821
+    omp_get_device_from_uid                 822
+    omp_get_uid_from_device                 823
     %ifndef stub
         __kmpc_set_default_allocator
         __kmpc_get_default_allocator
diff --git a/openmp/runtime/src/include/omp.h.var b/openmp/runtime/src/include/omp.h.var
index 74f385feb3ea5..e98df731ad888 100644
--- a/openmp/runtime/src/include/omp.h.var
+++ b/openmp/runtime/src/include/omp.h.var
@@ -536,6 +536,11 @@
 
     /* OpenMP 5.2 */
     extern int __KAI_KMPC_CONVENTION omp_in_explicit_task(void);
+    #define omp_invalid_device -2
+
+    /* OpenMP 6.0 */
+    extern int   __KAI_KMPC_CONVENTION  omp_get_device_from_uid(const char *DeviceUid);
+    extern const char *   __KAI_KMPC_CONVENTION  omp_get_uid_from_device(int DeviceNum);
 
     /* LLVM Extensions */
     extern void *llvm_omp_target_dynamic_shared_alloc(void);
diff --git a/openmp/runtime/src/include/omp_lib.F90.var b/openmp/runtime/src/include/omp_lib.F90.var
index 90d7e49ebf549..159b42ab5b5cc 100644
--- a/openmp/runtime/src/include/omp_lib.F90.var
+++ b/openmp/runtime/src/include/omp_lib.F90.var
@@ -215,6 +215,8 @@
 
         integer (kind=omp_interop_kind), parameter, public :: omp_interop_none = 0
 
+        integer (kind=omp_integer_kind), parameter, public :: omp_invalid_device = -2
+
         interface
 
 !         ***
@@ -417,6 +419,18 @@
             integer (kind=omp_integer_kind) omp_get_device_num
           end function omp_get_device_num
 
+          function omp_get_uid_from_device(device_num) bind(c)
+            use omp_lib_kinds
+            integer (kind=omp_integer_kind), value :: device_num
+            character (len=*) omp_get_uid_from_device
+          end function omp_get_uid_from_device
+
+          function omp_get_device_from_uid(device_uid) bind(c)
+            use omp_lib_kinds
+            character (len=*), value :: device_uid
+            integer (kind=omp_integer_kind) omp_get_device_from_uid
+          end function omp_get_device_from_uid
+
           function omp_pause_resource(kind, device_num) bind(c)
             use omp_lib_kinds
             integer (kind=omp_pause_resource_kind), value :: kind
diff --git a/openmp/runtime/src/include/omp_lib.h.var b/openmp/runtime/src/include/omp_lib.h.var
index a50bb018c7cc3..468eb03e99ef1 100644
--- a/openmp/runtime/src/include/omp_lib.h.var
+++ b/openmp/runtime/src/include/omp_lib.h.var
@@ -291,6 +291,9 @@
       integer(kind=omp_interop_kind)omp_interop_none
       parameter(omp_interop_none=0)
 
+      integer(kind=omp_integer_kind)omp_invalid_device
+      parameter(omp_invalid_device=-2)
+
       interface
 
 !       ***
@@ -486,6 +489,18 @@
           integer (kind=omp_integer_kind) omp_get_device_num
         end function omp_get_device_num
 
+        function omp_get_uid_from_device(device_num) bind(c)
+          import
+          integer (kind=omp_integer_kind), value :: device_num
+          character (len=*) omp_get_uid_from_device
+        end function omp_get_uid_from_device
+
+        function omp_get_device_from_uid(device_uid) bind(c)
+          import
+          character (len=*), value :: device_uid
+          integer (kind=omp_integer_kind) omp_get_device_from_uid
+        end function omp_get_device_from_uid
+
         function omp_pause_resource(kind, device_num) bind(c)
           import
           integer (kind=omp_pause_resource_kind), value :: kind
@@ -1159,6 +1174,8 @@
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_initial_device
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_num_devices
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_device_num
+!DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_uid_from_device
+!DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_device_from_uid
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_pause_resource
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_pause_resource_all
 !DIR$ ATTRIBUTES OFFLOAD:MIC :: omp_get_supported_active_levels
@@ -1242,6 +1259,8 @@
 !$omp declare target(omp_get_initial_device )
 !$omp declare target(omp_get_num_devices )
 !$omp declare target(omp_get_device_num )
+!$omp declare target(omp_get_uid_from_device )
+!$omp declare target(omp_get_device_from_uid )
 !$omp declare target(omp_pause_resource )
 !$omp declare target(omp_pause_resource_all )
 !$omp declare target(omp_get_supported_active_levels )
diff --git a/openmp/runtime/src/kmp_ftn_entry.h b/openmp/runtime/src/kmp_ftn_entry.h
index 2b0063eb23a0a..95cd3965a518d 100644
--- a/openmp/runtime/src/kmp_ftn_entry.h
+++ b/openmp/runtime/src/kmp_ftn_entry.h
@@ -1543,14 +1543,26 @@ int FTN_STDCALL KMP_EXPAND_NAME(FTN_GET_MAX_TASK_PRIORITY)(void) {
 #endif
 }
 
-// This function will be defined in libomptarget. When libomptarget is not
-// loaded, we assume we are on the host and return KMP_HOST_DEVICE.
+// These functions will be defined in libomptarget. When libomptarget is not
+// loaded, we assume we are on the host.
 // Compiler/libomptarget will handle this if called inside target.
 int FTN_STDCALL FTN_GET_DEVICE_NUM(void) KMP_WEAK_ATTRIBUTE_EXTERNAL;
 int FTN_STDCALL FTN_GET_DEVICE_NUM(void) {
   return KMP_EXPAND_NAME(FTN_GET_INITIAL_DEVICE)();
 }
 
+const char *FTN_STDCALL FTN_GET_UID_FROM_DEVICE(int device_num)
+    KMP_WEAK_ATTRIBUTE_EXTERNAL;
+const char *FTN_STDCALL FTN_GET_UID_FROM_DEVICE(int device_num) {
+  // Returns the same string as used by libomptarget
+  return "HOST";
+}
+int FTN_STDCALL FTN_GET_DEVICE_FROM_UID(const char *device_uid)
+    KMP_WEAK_ATTRIBUTE_EXTERNAL;
+int FTN_STDCALL FTN_GET_DEVICE_FROM_UID(const char *device_uid) {
+  return KMP_EXPAND_NAME(FTN_GET_INITIAL_DEVICE)();
+}
+
 // Compiler will ensure that this is only called from host in sequential region
 int FTN_STDCALL KMP_EXPAND_NAME(FTN_PAUSE_RESOURCE)(kmp_pause_status_t kind,
                                                     int device_num) {
diff --git a/openmp/runtime/src/kmp_ftn_os.h b/openmp/runtime/src/kmp_ftn_os.h
index ae0ed067235e5..c439a058f22b4 100644
--- a/openmp/runtime/src/kmp_ftn_os.h
+++ b/openmp/runtime/src/kmp_ftn_os.h
@@ -140,6 +140,8 @@
 #define FTN_GET_MEMSPACE_NUM_RESOURCES omp_get_memspace_num_resources
 #define FTN_GET_SUBMEMSPACE omp_get_submemspace
 #define FTN_GET_DEVICE_NUM omp_get_device_num
+#define FTN_GET_UID_FROM_DEVICE omp_get_uid_from_device
+#define FTN_GET_DEVICE_FROM_UID omp_get_device_from_uid
 #define FTN_SET_AFFINITY_FORMAT omp_set_affinity_format
 #define FTN_GET_AFFINITY_FORMAT omp_get_affinity_format
 #define FTN_DISPLAY_AFFINITY omp_display_affinity
@@ -289,6 +291,8 @@
 #define FTN_ALLOC omp_alloc_
 #define FTN_FREE omp_free_
 #define FTN_GET_DEVICE_NUM omp_get_device_num_
+#define FTN_GET_UID_FROM_DEVICE omp_get_uid_from_device_
+#define FTN_GET_DEVICE_FROM_UID omp_get_device_from_uid_
 #define FTN_SET_AFFINITY_FORMAT omp_set_affinity_format_
 #define FTN_GET_AFFINITY_FORMAT omp_get_affinity_format_
 #define FTN_DISPLAY_AFFINITY omp_display_affinity_
@@ -436,6 +440,8 @@
 #define FTN_GET_MEMSPACE_NUM_RESOURCES OMP_GET_MEMSPACE_NUM_RESOURCES
 #define FTN_GET_SUBMEMSPACE OMP_GET_SUBMEMSPACE
 #define FTN_GET_DEVICE_NUM OMP_GET_DEVICE_NUM
+#define FTN_GET_UID_FROM_DEVICE OMP_GET_UID_FROM_DEVICE
+#define FTN_GET_DEVICE_FROM_UID OMP_GET_DEVICE_FROM_UID
 #define FTN_SET_AFFINITY_FORMAT OMP_SET_AFFINITY_FORMAT
 #define FTN_GET_AFFINITY_FORMAT OMP_GET_AFFINITY_FORMAT
 #define FTN_DISPLAY_AFFINITY OMP_DISPLAY_AFFINITY
@@ -585,6 +591,8 @@
 #define FTN_ALLOC OMP_ALLOC_
 #define FTN_FREE OMP_FREE_
 #define FTN_GET_DEVICE_NUM OMP_GET_DEVICE_NUM_
+#define FTN_GET_UID_FROM_DEVICE OMP_GET_UID_FROM_DEVICE_
+#define FTN_GET_DEVICE_FROM_UID OMP_GET_DEVICE_FROM_UID_
 #define FTN_SET_AFFINITY_FORMAT OMP_SET_AFFINITY_FORMAT_
 #define FTN_GET_AFFINITY_FORMAT OMP_GET_AFFINITY_FORMAT_
 #define FTN_DISPLAY_AFFINITY OMP_DISPLAY_AFFINITY_
diff --git a/openmp/runtime/test/api/omp_device_uid.c b/openmp/runtime/test/api/omp_device_uid.c
new file mode 100644
index 0000000000000..975dad73f5b18
--- /dev/null
+++ b/openmp/runtime/test/api/omp_device_uid.c
@@ -0,0 +1,89 @@
+// RUN: %libomp-compile-and-run 2>&1 | FileCheck %s
+// Linking fails for icc 18
+// UNSUPPORTED: icc-18
+
+#include <omp_testsuite.h>
+#include <string.h>
+
+// Note that the device UIDs for the "fake" host devices used by libomptarget
+// will always be the same as the UID for the initial device (since it *is* the
+// same device).  The other way round, the device number returned for this UID
+// will always be the initial device.
+
+int is_host_device_uid(const char *device_uid) {
+  return strcmp(device_uid,
+                omp_get_uid_from_device(omp_get_initial_device())) == 0;
+}
+
+int test_omp_device_uid(int device_num) {
+  const char *device_uid = omp_get_uid_from_device(device_num);
+  if (device_uid == NULL) {
+    printf("FAIL for device %d: omp_get_uid_from_device returned NULL\n",
+           device_num);
+    return 0;
+  }
+
+  int device_num_from_uid = omp_get_device_from_uid(device_uid);
+  if (device_num_from_uid != (is_host_device_uid(device_uid)
+                                  ? omp_get_initial_device()
+                                  : device_num)) {
+    printf(
+        "FAIL for device %d: omp_get_device_from_uid returned %d (UID: %s)\n",
+        device_num, device_num_from_uid, device_uid);
+    return 0;
+  }
+
+  if (device_num == omp_get_initial_device())
+    return 1;
+
+  int success = 1;
+
+// Note that the following code may be executed on the host if the host is the
+// device
+#pragma omp target map(tofrom : success) device(device_num)
+  {
+    int device_num = omp_get_device_num();
+
+    // omp_get_uid_from_device() in the device runtime is a dummy function
+    // returning NULL
+    const char *device_uid_target = omp_get_uid_from_device(device_num);
+
+    // omp_get_device_from_uid() in the device runtime is a dummy function
+    // returning omp_invalid_device.
+    device_num_from_uid = omp_get_device_from_uid(device_uid_target);
+
+    // Depending on whether we're executing on the device or the host, we either
+    // got NULL as the device UID or the correct device UID.  Consequently,
+    // omp_get_device_from_uid() either returned omp_invalid_device or the
+    // correct device number (aka omp_get_initial_device()).
+    if (device_uid_target ? device_num_from_uid != omp_get_initial_device()
+                          : device_num_from_uid != omp_invalid_device) {
+      printf("FAIL for device %d (target): omp_get_device_from_uid returned %d "
+             "(UID: %s)\n",
+             device_num, device_num_from_uid, device_uid_target);
+      success = 0;
+    }
+  }
+
+  return success;
+}
+
+int main() {
+  int num_devices = omp_get_num_devices();
+  int num_failed = 0;
+  // (also test initial device aka num_devices)
+  for (int i = 0; i < num_devices + 1; i++) {
+    if (!test_omp_device_uid(i)) {
+      printf("FAIL for device %d\n", i);
+      num_failed++;
+    }
+  }
+  if (num_failed) {
+    printf("FAIL\n");
+    return 1;
+  }
+  printf("PASS\n");
+  return 0;
+}
+
+// CHECK: PASS

offload/libomptarget/OpenMP/API.cpp

CatherineMoore · 2025-10-21T12:54:15Z

@CatherineMoore

openmp/runtime/src/kmp_ftn_entry.h

offload/test/api/omp_device_uid.c

offload/libomptarget/OpenMP/API.cpp

openmp/device/include/DeviceTypes.h

offload/libomptarget/OpenMP/API.cpp

jhuber6 · 2025-10-21T19:35:23Z

Do we have a good way to get a UUID for the host device?

ro-i · 2025-10-21T19:39:16Z

What do you mean? Regarding the discussion of the fake host devices in #164391? Or whether to put a shared constant in libomp and access it from libomptarget similar to int __kmpc_get_target_offload(void) __attribute__((weak));?

kevinsala · 2025-10-22T23:18:35Z

offload/libomptarget/OpenMP/API.cpp

+  }
+  if (DeviceNum == omp_get_initial_device()) {
+    DP("Call to omp_get_uid_from_device returning initial device UID\n");
+    return GenericPluginTy::getInitialDeviceUid();


I still don't understand why libomptarget has to ask the device plugins what's the UID of the host. It seems that libomptarget should be the one providing that info.

If the function is still needed, I would rename to getHostUID or something similar. Initial device only makes sense in the OpenMP context.

Libomptarget isn't available for offload-info etc. tho (see offload/liboffload/src/OffloadImpl.cpp in #164391)

I previously called this function getHostDeviceUid, but then thought that this naming might clash with the fact that there are these other virtual host devices.
But idk, I can rename it to getHostDeviceUid or getHostUid again.

Maybe, getHostUid is a good suggestion because it doesn't contain the word "device"

Although it still is a device ... So ig I'll use getHostDeviceUid again

Use the implementation in libomptarget. If libomptarget is not available, always return the UID / device number of the host / the initial device.

ro-i requested review from dhruvachak, jhuber6, mjklemm and shiltian October 21, 2025 10:41

llvmbot added openmp:libomp OpenMP host runtime openmp:libomptarget OpenMP offload runtime offload labels Oct 21, 2025

adurang reviewed Oct 21, 2025

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mjklemm requested changes Oct 21, 2025

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kevinsala reviewed Oct 21, 2025

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ro-i force-pushed the users/ro-i/openmp-device-uid branch from 039374b to fda29e1 Compare October 21, 2025 19:33

ro-i force-pushed the users/ro-i/openmp-device-uid branch 3 times, most recently from 89c5515 to b963a70 Compare October 22, 2025 14:43

kevinsala reviewed Oct 22, 2025

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ro-i force-pushed the users/ro-i/openmp-device-uid branch from b963a70 to a18141c Compare October 23, 2025 07:23

ro-i force-pushed the users/ro-i/offload-device-uid branch from fb02cf7 to fff258a Compare October 23, 2025 07:33

ro-i added 7 commits October 23, 2025 02:36

[OpenMP] Implement omp_get_uid_from_device() / omp_get_device_from_uid()

6379a0a

Use the implementation in libomptarget. If libomptarget is not available, always return the UID / device number of the host / the initial device.

implement feedback

884a00d

adapt to offload plugin device UID getter

aedaad5

adapt to offload API

316862e

fix libomptarget symbol lookup similar to how other functions handle it

9fbf2b6

adapt tests

5d67aca

rename getInitialDeviceUid to getHostDeviceUid again

6426ccb

ro-i force-pushed the users/ro-i/openmp-device-uid branch from a18141c to 6426ccb Compare October 23, 2025 07:43

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[OpenMP] Implement omp_get_uid_from_device() / omp_get_device_from_uid() #164392

[OpenMP] Implement omp_get_uid_from_device() / omp_get_device_from_uid() #164392

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