[Openmp-commits] [openmp] [libomptarget][OpenMP] Initial implementation of omp_target_memset() and omp_target_memset_async() (PR #68706)
Michael Klemm via Openmp-commits
openmp-commits at lists.llvm.org
Wed Oct 11 07:44:23 PDT 2023
https://github.com/mjklemm updated https://github.com/llvm/llvm-project/pull/68706
>From 06d5eefaffca64e9b99f3a88b3f88f2203fa3243 Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Sun, 1 Oct 2023 17:28:22 +0200
Subject: [PATCH 1/7] Add stub functions and exports for omp_target_memset()
---
openmp/libomptarget/include/omptarget.h | 1 +
openmp/libomptarget/src/api.cpp | 11 +++++
openmp/libomptarget/src/exports | 2 +
.../libomptarget/test/api/omp_target_memset.c | 45 +++++++++++++++++++
openmp/runtime/src/dllexports | 2 +
openmp/runtime/src/include/omp.h.var | 5 +++
openmp/runtime/src/include/omp_lib.f90.var | 22 +++++++++
openmp/runtime/src/include/omp_lib.h.var | 22 +++++++++
openmp/runtime/src/kmp_ftn_os.h | 2 +
9 files changed, 112 insertions(+)
create mode 100644 openmp/libomptarget/test/api/omp_target_memset.c
diff --git a/openmp/libomptarget/include/omptarget.h b/openmp/libomptarget/include/omptarget.h
index f87557a69eff272..e1f0f77849fa206 100644
--- a/openmp/libomptarget/include/omptarget.h
+++ b/openmp/libomptarget/include/omptarget.h
@@ -312,6 +312,7 @@ int omp_target_memcpy_rect(void *Dst, const void *Src, size_t ElementSize,
const size_t *DstDimensions,
const size_t *SrcDimensions, int DstDevice,
int SrcDevice);
+void *omp_target_memset(void *Ptr, int C, size_t N, int DeviceNum);
int omp_target_associate_ptr(const void *HostPtr, const void *DevicePtr,
size_t Size, size_t DeviceOffset, int DeviceNum);
int omp_target_disassociate_ptr(const void *HostPtr, int DeviceNum);
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index 942df8fdb94d660..595b234d535c8e0 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -241,6 +241,17 @@ static int libomp_target_memcpy_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
return Rc;
}
+EXTERN void * omp_target_memset(void * Ptr, int C, size_t N, int DeviceNum) {
+ return nullptr;
+}
+
+EXTERN void * omp_target_memset_async(void * Ptr, int C, size_t N, int DeviceNum,
+ int DepObjCount,
+ omp_depend_t * DepObjList) {
+ return nullptr;
+}
+
+
// Allocate and launch helper task
static int libomp_helper_task_creation(TargetMemcpyArgsTy *Args,
int DepObjCount,
diff --git a/openmp/libomptarget/src/exports b/openmp/libomptarget/src/exports
index c29c8d03fb1276f..af882a264264725 100644
--- a/openmp/libomptarget/src/exports
+++ b/openmp/libomptarget/src/exports
@@ -44,6 +44,8 @@ VERS1.0 {
omp_target_memcpy_rect;
omp_target_memcpy_async;
omp_target_memcpy_rect_async;
+ omp_target_memset;
+ omp_target_memset_async;
omp_target_associate_ptr;
omp_target_disassociate_ptr;
llvm_omp_target_alloc_host;
diff --git a/openmp/libomptarget/test/api/omp_target_memset.c b/openmp/libomptarget/test/api/omp_target_memset.c
new file mode 100644
index 000000000000000..ea0c6d73fbdeefb
--- /dev/null
+++ b/openmp/libomptarget/test/api/omp_target_memset.c
@@ -0,0 +1,45 @@
+// RUN: %libomptarget-compile-and-run-generic
+
+#include "stdio.h"
+#include <omp.h>
+#include <stdlib.h>
+
+int main() {
+ int d = omp_get_default_device();
+ int id = omp_get_initial_device();
+ int q[128], i;
+ void *p;
+ void *result;
+
+ if (d < 0 || d >= omp_get_num_devices())
+ d = id;
+
+ p = omp_target_alloc(130 * sizeof(int), d);
+ if (p == NULL)
+ return 0;
+
+ for (i = 0; i < 128; i++)
+ q[i] = i;
+
+ result = omp_target_memset(p, 0, 130 * sizeof(int), d);
+ if (result != p) {
+ abort();
+ }
+
+ int q2[128];
+ for (i = 0; i < 128; ++i)
+ q2[i] = i;
+ if (omp_target_memcpy_async(q2, p, 128 * sizeof(int), 0, sizeof(int), id, d,
+ 0, NULL))
+ abort();
+
+#pragma omp taskwait
+
+ for (i = 0; i < 128; ++i)
+ if (q2[i] != 0)
+ abort();
+
+ omp_target_free(p, d);
+
+ return 0;
+}
diff --git a/openmp/runtime/src/dllexports b/openmp/runtime/src/dllexports
index e69cf6670e81489..0d49643709e0a05 100644
--- a/openmp/runtime/src/dllexports
+++ b/openmp/runtime/src/dllexports
@@ -518,6 +518,8 @@ kmp_set_warnings_off 780
omp_target_memcpy_rect 887
omp_target_associate_ptr 888
omp_target_disassociate_ptr 889
+ omp_target_memset 3000
+ omp_target_memset_async 3001
%endif
kmp_set_disp_num_buffers 890
diff --git a/openmp/runtime/src/include/omp.h.var b/openmp/runtime/src/include/omp.h.var
index 1b2c467a2a12d8a..f372402be37d39c 100644
--- a/openmp/runtime/src/include/omp.h.var
+++ b/openmp/runtime/src/include/omp.h.var
@@ -236,6 +236,11 @@
extern int __KAI_KMPC_CONVENTION omp_target_memcpy_rect_async(void *, const void *, size_t, int, const size_t *,
const size_t *, const size_t *, const size_t *, const size_t *, int, int,
int, omp_depend_t *);
+
+ /* OpenMP 6.0 device memory routines */
+ extern void * __KAI_KMPC_CONVENTION omp_target_memset(void *, int, size_t, int);
+ extern void * __KAI_KMPC_CONVENTION omp_target_memset_async(void *, int, size_t, int, int, omp_depend_t *);
+
/*!
* The `omp_get_mapped_ptr` routine returns the device pointer that is associated with a host pointer for a given device.
*/
diff --git a/openmp/runtime/src/include/omp_lib.f90.var b/openmp/runtime/src/include/omp_lib.f90.var
index c72287422809aef..1ca542db3767ef2 100644
--- a/openmp/runtime/src/include/omp_lib.f90.var
+++ b/openmp/runtime/src/include/omp_lib.f90.var
@@ -635,6 +635,28 @@
integer (omp_depend_kind), optional :: depobj_list(*)
end function omp_target_memcpy_rect_async
+ function omp_target_memset(ptr, val, count, device_num) bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_int, c_size_t
+ type(c_ptr) :: omp_target_memset
+ type(c_ptr), value :: ptr
+ integer(c_int), value :: val
+ integer(c_size_t), value :: count
+ integer(c_int), value :: device_num
+ end function
+
+ function omp_target_memset_async(ptr, val, count, device_num, &
+ depobj_count, depobj_list) bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_int, c_size_t
+ use omp_lib_kinds
+ type(c_ptr) :: omp_target_memset_async
+ type(c_ptr), value :: ptr
+ integer(c_int), value :: val
+ integer(c_size_t), value :: count
+ integer(c_int), value :: device_num
+ integer(c_int), value :: depobj_count
+ integer(omp_depend_kind), optional :: depobj_list(*)
+ end function
+
function omp_target_associate_ptr(host_ptr, device_ptr, size, &
device_offset, device_num) bind(c)
use omp_lib_kinds
diff --git a/openmp/runtime/src/include/omp_lib.h.var b/openmp/runtime/src/include/omp_lib.h.var
index 9f5e58515e75159..d20aade6ef8b327 100644
--- a/openmp/runtime/src/include/omp_lib.h.var
+++ b/openmp/runtime/src/include/omp_lib.h.var
@@ -732,6 +732,28 @@
integer(omp_depend_kind), optional :: depobj_list(*)
end function omp_target_memcpy_rect_async
+ function omp_target_memset(ptr, val, count, device_num) bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_int, c_size_t
+ type(c_ptr) :: omp_target_memset
+ type(c_ptr), value :: ptr
+ integer(c_int), value :: val
+ integer(c_size_t), value :: count
+ integer(c_int), value :: device_num
+ end function
+
+ function omp_target_memset_async(ptr, val, count, device_num, &
+ depobj_count, depobj_list) bind(c)
+ use, intrinsic :: iso_c_binding, only : c_ptr, c_int, c_size_t
+ use omp_lib_kinds
+ type(c_ptr) :: omp_target_memset_async
+ type(c_ptr), value :: ptr
+ integer(c_int), value :: val
+ integer(c_size_t), value :: count
+ integer(c_int), value :: device_num
+ integer(c_int), value :: depobj_count
+ integer(omp_depend_kind), optional :: depobj_list(*)
+ end function
+
function omp_target_associate_ptr(host_ptr, device_ptr, size, &
& device_offset, device_num) bind(c)
use, intrinsic :: iso_c_binding, only : c_ptr, c_size_t, c_int
diff --git a/openmp/runtime/src/kmp_ftn_os.h b/openmp/runtime/src/kmp_ftn_os.h
index d37c9c86028eb13..7d595b947f4a9de 100644
--- a/openmp/runtime/src/kmp_ftn_os.h
+++ b/openmp/runtime/src/kmp_ftn_os.h
@@ -116,6 +116,8 @@
#define FTN_TARGET_IS_PRESENT omp_target_is_present
#define FTN_TARGET_MEMCPY omp_target_memcpy
#define FTN_TARGET_MEMCPY_RECT omp_target_memcpy_rect
+#define FTN_TARGET_MEMSET omp_target_memset
+#define FTN_TARGET_MEMSET_ASYNC omp_target_memset_async
#define FTN_TARGET_ASSOCIATE_PTR omp_target_associate_ptr
#define FTN_TARGET_DISASSOCIATE_PTR omp_target_disassociate_ptr
#endif
>From c1791d6b9509045b38f16b77959fdc0b4d5b7b78 Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Mon, 2 Oct 2023 16:14:55 +0200
Subject: [PATCH 2/7] Implement a slow-path version of omp_target_memset*()
There is a TODO to implement a fast path that uses an on-device
kernel instead of the host-based memory fill operation. This may
require some additional plumbing to have kernels in libomptarget.so
---
openmp/libomptarget/src/api.cpp | 116 +++++++++++++++++++++++++++---
openmp/libomptarget/src/private.h | 13 ++++
2 files changed, 121 insertions(+), 8 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index 595b234d535c8e0..c8675b698544f3a 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -241,21 +241,121 @@ static int libomp_target_memcpy_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
return Rc;
}
+static int libomp_target_memset_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
+ if (!Task) {
+ return OFFLOAD_FAIL;
+ }
+
+ auto *Args = reinterpret_cast<TargetMemsetArgsTy *>(Task->shareds);
+ if (!Args) {
+ return OFFLOAD_FAIL;
+ }
+
+ // call omp_target_memset()
+ omp_target_memset(Args->Ptr, Args->C, Args->N, Args->DeviceNum);
+
+ delete Args;
+
+ return OFFLOAD_SUCCESS;
+}
+
+static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
+ int DepObjCount,
+ omp_depend_t * DepObjList) {
+ // Create global thread ID
+ int Gtid = __kmpc_global_thread_num(nullptr);
+ int (*Fn)(kmp_int32, kmp_task_t *) = &libomp_target_memset_async_helper;
+
+ // Setup the hidden helper flags
+ kmp_int32 Flags = 0;
+ kmp_tasking_flags_t *InputFlags = (kmp_tasking_flags_t *)&Flags;
+ InputFlags->hidden_helper = 1;
+
+ // Alloc the helper task
+ kmp_task_t *Task = __kmpc_omp_target_task_alloc(nullptr, Gtid, Flags,
+ sizeof(kmp_task_t), 0, Fn, -1);
+ if (!Task) {
+ delete Args;
+ return OFFLOAD_FAIL;
+ }
+
+ // Setup the arguments for the helper task
+ Task->shareds = Args;
+
+ // Convert types of depend objects
+ llvm::SmallVector<kmp_depend_info_t> DepObjs;
+ for (int i = 0; i < DepObjCount; i++) {
+ omp_depend_t DepObj = DepObjList[i];
+ DepObjs.push_back(*((kmp_depend_info_t *)DepObj));
+ }
+
+ // Launch the helper task
+ int Rc = __kmpc_omp_task_with_deps(nullptr, Gtid, Task, DepObjCount,
+ DepObjs.data(), 0, nullptr);
+
+ return Rc;
+}
+
EXTERN void * omp_target_memset(void * Ptr, int C, size_t N, int DeviceNum) {
- return nullptr;
+ TIMESCOPE();
+ DP("Call to omp_target_memset, device %d, device pointer %p, size %zu\n",
+ DeviceNum, Ptr, N);
+
+ // Behave as a no-op if N==0 or if Ptr is nullptr (as a useful implementation
+ // of unspecified behavior, see OpenMP spec).
+ if (!Ptr || N == 0) {
+ return Ptr;
+ }
+
+ if (DeviceNum == omp_get_initial_device()) {
+ DP("filling memory on host via memset");
+ memset(Ptr, C, N); // ignore return value, memset() cannot fail
+ }
+ else {
+ // TODO: replace the omp_target_memset() slow path with the fast path.
+ // That will require the ability to execute a kernel from within
+ // libomptarget.so (which we do not have at the moment).
+
+ // This is a very slow path: create a filled array on the host and upload
+ // it to the GPU device.
+ int InitialDevice = omp_get_initial_device();
+ void * Shadow = omp_target_alloc(N, InitialDevice);
+ memset(Shadow, C, N);
+ omp_target_memcpy(Ptr, Shadow, N, 0, 0, DeviceNum, InitialDevice);
+ omp_target_free(Shadow, InitialDevice);
+ }
+
+ DP("omp_target_memset returns %p\n", Ptr);
+ return Ptr;
}
+
EXTERN void * omp_target_memset_async(void * Ptr, int C, size_t N, int DeviceNum,
int DepObjCount,
omp_depend_t * DepObjList) {
- return nullptr;
-}
+ DP("Call to omp_target_memset_async, device %d, device pointer %p, size %zu",
+ DeviceNum, Ptr, N);
+
+ // Behave as a no-op if N==0 or if Ptr is nullptr (as a useful implementation
+ // of unspecified behavior, see OpenMP spec).
+ if (!Ptr || N == 0) {
+ return Ptr;
+ }
+ // Create the task object to deal with the async invocation
+ auto *Args = new TargetMemsetArgsTy{Ptr, C, N, DeviceNum};
+
+ // omp_target_memset_async() cannot fail via a return code, so ignore the
+ // return code of the helper function
+ (void) libomp_helper_memset_task_creation(Args, DepObjCount, DepObjList);
+
+ return Ptr;
+}
// Allocate and launch helper task
-static int libomp_helper_task_creation(TargetMemcpyArgsTy *Args,
- int DepObjCount,
- omp_depend_t *DepObjList) {
+static int libomp_helper_memcpy_task_creation(TargetMemcpyArgsTy *Args,
+ int DepObjCount,
+ omp_depend_t *DepObjList) {
// Create global thread ID
int Gtid = __kmpc_global_thread_num(nullptr);
int (*Fn)(kmp_int32, kmp_task_t *) = &libomp_target_memcpy_async_helper;
@@ -313,7 +413,7 @@ EXTERN int omp_target_memcpy_async(void *Dst, const void *Src, size_t Length,
Dst, Src, Length, DstOffset, SrcOffset, DstDevice, SrcDevice);
// Create and launch helper task
- int Rc = libomp_helper_task_creation(Args, DepObjCount, DepObjList);
+ int Rc = libomp_helper_memcpy_task_creation(Args, DepObjCount, DepObjList);
DP("omp_target_memcpy_async returns %d\n", Rc);
return Rc;
@@ -410,7 +510,7 @@ EXTERN int omp_target_memcpy_rect_async(
DstDimensions, SrcDimensions, DstDevice, SrcDevice);
// Create and launch helper task
- int Rc = libomp_helper_task_creation(Args, DepObjCount, DepObjList);
+ int Rc = libomp_helper_memcpy_task_creation(Args, DepObjCount, DepObjList);
DP("omp_target_memcpy_rect_async returns %d\n", Rc);
return Rc;
diff --git a/openmp/libomptarget/src/private.h b/openmp/libomptarget/src/private.h
index cbce15b63a3eba2..ec1ecd5503e14fb 100644
--- a/openmp/libomptarget/src/private.h
+++ b/openmp/libomptarget/src/private.h
@@ -253,6 +253,19 @@ struct TargetMemcpyArgsTy {
DstOffsets(DstOffsets), SrcOffsets(SrcOffsets),
DstDimensions(DstDimensions), SrcDimensions(SrcDimensions){};
};
+
+struct TargetMemsetArgsTy {
+ /**
+ * Common attributes of a memset operation
+ */
+ void *Ptr;
+ int C;
+ size_t N;
+ int DeviceNum;
+
+ // no constructors defined, because this is a PoD
+};
+
// Invalid GTID as defined by libomp; keep in sync
#define KMP_GTID_DNE (-2)
#ifdef __cplusplus
>From 97dba336319777ee3c06ed76be2dc41ee87f01cf Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Wed, 4 Oct 2023 16:05:38 +0200
Subject: [PATCH 3/7] Refactor code a bit to reduce code duplication
---
openmp/libomptarget/src/api.cpp | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index c8675b698544f3a..baf5878595b123c 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -259,6 +259,16 @@ static int libomp_target_memset_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
return OFFLOAD_SUCCESS;
}
+static inline
+void ConvertDepObjVector(llvm::SmallVector<kmp_depend_info_t> &Vec,
+ int DepObjCount, omp_depend_t * DepObjList) {
+ for (int i = 0; i < DepObjCount; i++) {
+ omp_depend_t DepObj = DepObjList[i];
+ Vec.push_back(*((kmp_depend_info_t *)DepObj));
+ }
+}
+
+
static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
int DepObjCount,
omp_depend_t * DepObjList) {
@@ -284,10 +294,7 @@ static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
// Convert types of depend objects
llvm::SmallVector<kmp_depend_info_t> DepObjs;
- for (int i = 0; i < DepObjCount; i++) {
- omp_depend_t DepObj = DepObjList[i];
- DepObjs.push_back(*((kmp_depend_info_t *)DepObj));
- }
+ ConvertDepObjVector(DepObjs, DepObjCount, DepObjList);
// Launch the helper task
int Rc = __kmpc_omp_task_with_deps(nullptr, Gtid, Task, DepObjCount,
@@ -381,10 +388,7 @@ static int libomp_helper_memcpy_task_creation(TargetMemcpyArgsTy *Args,
// Convert the type of depend objects
llvm::SmallVector<kmp_depend_info_t> DepObjs;
- for (int i = 0; i < DepObjCount; i++) {
- omp_depend_t DepObj = DepObjList[i];
- DepObjs.push_back(*((kmp_depend_info_t *)DepObj));
- }
+ ConvertDepObjVector(DepObjs, DepObjCount, DepObjList);
// Launch the helper task
int Rc = __kmpc_omp_task_with_deps(nullptr, Gtid, Ptr, DepObjCount,
>From 33e7eb64f56a8e18eb6498a332b98fe8a89f70c2 Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Fri, 6 Oct 2023 14:44:42 +0200
Subject: [PATCH 4/7] Apply formatting rules
---
openmp/libomptarget/src/api.cpp | 39 +++++++++++++++------------------
1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index baf5878595b123c..0b8a21652ee9b24 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -259,19 +259,18 @@ static int libomp_target_memset_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
return OFFLOAD_SUCCESS;
}
-static inline
-void ConvertDepObjVector(llvm::SmallVector<kmp_depend_info_t> &Vec,
- int DepObjCount, omp_depend_t * DepObjList) {
- for (int i = 0; i < DepObjCount; i++) {
+static inline void
+ConvertDepObjVector(llvm::SmallVector<kmp_depend_info_t> &Vec, int DepObjCount,
+ omp_depend_t *DepObjList) {
+ for (int i = 0; i < DepObjCount; ++i) {
omp_depend_t DepObj = DepObjList[i];
Vec.push_back(*((kmp_depend_info_t *)DepObj));
}
}
-
static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
int DepObjCount,
- omp_depend_t * DepObjList) {
+ omp_depend_t *DepObjList) {
// Create global thread ID
int Gtid = __kmpc_global_thread_num(nullptr);
int (*Fn)(kmp_int32, kmp_task_t *) = &libomp_target_memset_async_helper;
@@ -282,8 +281,8 @@ static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
InputFlags->hidden_helper = 1;
// Alloc the helper task
- kmp_task_t *Task = __kmpc_omp_target_task_alloc(nullptr, Gtid, Flags,
- sizeof(kmp_task_t), 0, Fn, -1);
+ kmp_task_t *Task = __kmpc_omp_target_task_alloc(
+ nullptr, Gtid, Flags, sizeof(kmp_task_t), 0, Fn, -1);
if (!Task) {
delete Args;
return OFFLOAD_FAIL;
@@ -303,7 +302,7 @@ static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
return Rc;
}
-EXTERN void * omp_target_memset(void * Ptr, int C, size_t N, int DeviceNum) {
+EXTERN void *omp_target_memset(void *Ptr, int C, size_t N, int DeviceNum) {
TIMESCOPE();
DP("Call to omp_target_memset, device %d, device pointer %p, size %zu\n",
DeviceNum, Ptr, N);
@@ -316,9 +315,8 @@ EXTERN void * omp_target_memset(void * Ptr, int C, size_t N, int DeviceNum) {
if (DeviceNum == omp_get_initial_device()) {
DP("filling memory on host via memset");
- memset(Ptr, C, N); // ignore return value, memset() cannot fail
- }
- else {
+ memset(Ptr, C, N); // ignore return value, memset() cannot fail
+ } else {
// TODO: replace the omp_target_memset() slow path with the fast path.
// That will require the ability to execute a kernel from within
// libomptarget.so (which we do not have at the moment).
@@ -326,20 +324,19 @@ EXTERN void * omp_target_memset(void * Ptr, int C, size_t N, int DeviceNum) {
// This is a very slow path: create a filled array on the host and upload
// it to the GPU device.
int InitialDevice = omp_get_initial_device();
- void * Shadow = omp_target_alloc(N, InitialDevice);
- memset(Shadow, C, N);
- omp_target_memcpy(Ptr, Shadow, N, 0, 0, DeviceNum, InitialDevice);
- omp_target_free(Shadow, InitialDevice);
+ void *Shadow = omp_target_alloc(N, InitialDevice);
+ (void)memset(Shadow, C, N);
+ (void)omp_target_memcpy(Ptr, Shadow, N, 0, 0, DeviceNum, InitialDevice);
+ (void)omp_target_free(Shadow, InitialDevice);
}
DP("omp_target_memset returns %p\n", Ptr);
return Ptr;
}
-
-EXTERN void * omp_target_memset_async(void * Ptr, int C, size_t N, int DeviceNum,
- int DepObjCount,
- omp_depend_t * DepObjList) {
+EXTERN void *omp_target_memset_async(void *Ptr, int C, size_t N, int DeviceNum,
+ int DepObjCount,
+ omp_depend_t *DepObjList) {
DP("Call to omp_target_memset_async, device %d, device pointer %p, size %zu",
DeviceNum, Ptr, N);
@@ -354,7 +351,7 @@ EXTERN void * omp_target_memset_async(void * Ptr, int C, size_t N, int DeviceNum
// omp_target_memset_async() cannot fail via a return code, so ignore the
// return code of the helper function
- (void) libomp_helper_memset_task_creation(Args, DepObjCount, DepObjList);
+ (void)libomp_helper_memset_task_creation(Args, DepObjCount, DepObjList);
return Ptr;
}
>From 7933bfa051acaecd801eb95bddcdbae8456d06c3 Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Tue, 10 Oct 2023 17:16:01 +0200
Subject: [PATCH 5/7] (Partly) Address feedback by shiltian
---
openmp/libomptarget/src/api.cpp | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index 0b8a21652ee9b24..c8e74ee89bf1421 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -242,9 +242,8 @@ static int libomp_target_memcpy_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
}
static int libomp_target_memset_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
- if (!Task) {
+ if (!Task)
return OFFLOAD_FAIL;
- }
auto *Args = reinterpret_cast<TargetMemsetArgsTy *>(Task->shareds);
if (!Args) {
@@ -302,20 +301,20 @@ static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
return Rc;
}
-EXTERN void *omp_target_memset(void *Ptr, int C, size_t N, int DeviceNum) {
+EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes, int DeviceNum) {
TIMESCOPE();
DP("Call to omp_target_memset, device %d, device pointer %p, size %zu\n",
- DeviceNum, Ptr, N);
+ DeviceNum, Ptr, NumBytes);
// Behave as a no-op if N==0 or if Ptr is nullptr (as a useful implementation
// of unspecified behavior, see OpenMP spec).
- if (!Ptr || N == 0) {
+ if (!Ptr || NumBytes == 0) {
return Ptr;
}
if (DeviceNum == omp_get_initial_device()) {
DP("filling memory on host via memset");
- memset(Ptr, C, N); // ignore return value, memset() cannot fail
+ memset(Ptr, ByteVal, NumBytes); // ignore return value, memset() cannot fail
} else {
// TODO: replace the omp_target_memset() slow path with the fast path.
// That will require the ability to execute a kernel from within
@@ -324,9 +323,9 @@ EXTERN void *omp_target_memset(void *Ptr, int C, size_t N, int DeviceNum) {
// This is a very slow path: create a filled array on the host and upload
// it to the GPU device.
int InitialDevice = omp_get_initial_device();
- void *Shadow = omp_target_alloc(N, InitialDevice);
- (void)memset(Shadow, C, N);
- (void)omp_target_memcpy(Ptr, Shadow, N, 0, 0, DeviceNum, InitialDevice);
+ void *Shadow = omp_target_alloc(NumBytes, InitialDevice);
+ (void)memset(Shadow, ByteVal, NumBytes);
+ (void)omp_target_memcpy(Ptr, Shadow, NumBytes, 0, 0, DeviceNum, InitialDevice);
(void)omp_target_free(Shadow, InitialDevice);
}
@@ -334,20 +333,20 @@ EXTERN void *omp_target_memset(void *Ptr, int C, size_t N, int DeviceNum) {
return Ptr;
}
-EXTERN void *omp_target_memset_async(void *Ptr, int C, size_t N, int DeviceNum,
+EXTERN void *omp_target_memset_async(void *Ptr, int ByteVal, size_t NumBytes, int DeviceNum,
int DepObjCount,
omp_depend_t *DepObjList) {
DP("Call to omp_target_memset_async, device %d, device pointer %p, size %zu",
- DeviceNum, Ptr, N);
+ DeviceNum, Ptr, NumBytes);
// Behave as a no-op if N==0 or if Ptr is nullptr (as a useful implementation
// of unspecified behavior, see OpenMP spec).
- if (!Ptr || N == 0) {
+ if (!Ptr || NumBytes == 0) {
return Ptr;
}
// Create the task object to deal with the async invocation
- auto *Args = new TargetMemsetArgsTy{Ptr, C, N, DeviceNum};
+ auto *Args = new TargetMemsetArgsTy{Ptr, ByteVal, NumBytes, DeviceNum};
// omp_target_memset_async() cannot fail via a return code, so ignore the
// return code of the helper function
>From 5e87a5708d4f7902a14893b7a5e5af38c311759b Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Tue, 10 Oct 2023 19:20:54 +0200
Subject: [PATCH 6/7] Slightly reduce code complexity, merge task helpers for
memset/memcpy
---
openmp/libomptarget/src/api.cpp | 72 +++++++++------------------------
1 file changed, 19 insertions(+), 53 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index c8e74ee89bf1421..ff51c73b58da162 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -210,7 +210,7 @@ EXTERN int omp_target_memcpy(void *Dst, const void *Src, size_t Length,
}
// The helper function that calls omp_target_memcpy or omp_target_memcpy_rect
-static int libomp_target_memcpy_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
+static int libomp_target_memcpy_async_task(kmp_int32 Gtid, kmp_task_t *Task) {
if (Task == nullptr)
return OFFLOAD_FAIL;
@@ -241,7 +241,7 @@ static int libomp_target_memcpy_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
return Rc;
}
-static int libomp_target_memset_async_helper(kmp_int32 Gtid, kmp_task_t *Task) {
+static int libomp_target_memset_async_task(kmp_int32 Gtid, kmp_task_t *Task) {
if (!Task)
return OFFLOAD_FAIL;
@@ -267,12 +267,12 @@ ConvertDepObjVector(llvm::SmallVector<kmp_depend_info_t> &Vec, int DepObjCount,
}
}
-static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
- int DepObjCount,
- omp_depend_t *DepObjList) {
+template <class T>
+static inline int
+libomp_helper_task_creation(T *Args, int (*Fn)(kmp_int32, kmp_task_t *),
+ int DepObjCount, omp_depend_t *DepObjList) {
// Create global thread ID
int Gtid = __kmpc_global_thread_num(nullptr);
- int (*Fn)(kmp_int32, kmp_task_t *) = &libomp_target_memset_async_helper;
// Setup the hidden helper flags
kmp_int32 Flags = 0;
@@ -301,7 +301,8 @@ static int libomp_helper_memset_task_creation(TargetMemsetArgsTy *Args,
return Rc;
}
-EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes, int DeviceNum) {
+EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes,
+ int DeviceNum) {
TIMESCOPE();
DP("Call to omp_target_memset, device %d, device pointer %p, size %zu\n",
DeviceNum, Ptr, NumBytes);
@@ -325,7 +326,8 @@ EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes, int Devi
int InitialDevice = omp_get_initial_device();
void *Shadow = omp_target_alloc(NumBytes, InitialDevice);
(void)memset(Shadow, ByteVal, NumBytes);
- (void)omp_target_memcpy(Ptr, Shadow, NumBytes, 0, 0, DeviceNum, InitialDevice);
+ (void)omp_target_memcpy(Ptr, Shadow, NumBytes, 0, 0, DeviceNum,
+ InitialDevice);
(void)omp_target_free(Shadow, InitialDevice);
}
@@ -333,66 +335,28 @@ EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes, int Devi
return Ptr;
}
-EXTERN void *omp_target_memset_async(void *Ptr, int ByteVal, size_t NumBytes, int DeviceNum,
- int DepObjCount,
+EXTERN void *omp_target_memset_async(void *Ptr, int ByteVal, size_t NumBytes,
+ int DeviceNum, int DepObjCount,
omp_depend_t *DepObjList) {
DP("Call to omp_target_memset_async, device %d, device pointer %p, size %zu",
DeviceNum, Ptr, NumBytes);
// Behave as a no-op if N==0 or if Ptr is nullptr (as a useful implementation
// of unspecified behavior, see OpenMP spec).
- if (!Ptr || NumBytes == 0) {
+ if (!Ptr || NumBytes == 0)
return Ptr;
- }
// Create the task object to deal with the async invocation
auto *Args = new TargetMemsetArgsTy{Ptr, ByteVal, NumBytes, DeviceNum};
// omp_target_memset_async() cannot fail via a return code, so ignore the
// return code of the helper function
- (void)libomp_helper_memset_task_creation(Args, DepObjCount, DepObjList);
+ (void)libomp_helper_task_creation(Args, &libomp_target_memset_async_task,
+ DepObjCount, DepObjList);
return Ptr;
}
-// Allocate and launch helper task
-static int libomp_helper_memcpy_task_creation(TargetMemcpyArgsTy *Args,
- int DepObjCount,
- omp_depend_t *DepObjList) {
- // Create global thread ID
- int Gtid = __kmpc_global_thread_num(nullptr);
- int (*Fn)(kmp_int32, kmp_task_t *) = &libomp_target_memcpy_async_helper;
-
- // Setup the hidden helper flags;
- kmp_int32 Flags = 0;
- kmp_tasking_flags_t *InputFlags = (kmp_tasking_flags_t *)&Flags;
- InputFlags->hidden_helper = 1;
-
- // Alloc helper task
- kmp_task_t *Ptr = __kmpc_omp_target_task_alloc(nullptr, Gtid, Flags,
- sizeof(kmp_task_t), 0, Fn, -1);
-
- if (Ptr == nullptr) {
- // Task allocation failed, delete the argument object
- delete Args;
-
- return OFFLOAD_FAIL;
- }
-
- // Setup the arguments passed to helper task
- Ptr->shareds = Args;
-
- // Convert the type of depend objects
- llvm::SmallVector<kmp_depend_info_t> DepObjs;
- ConvertDepObjVector(DepObjs, DepObjCount, DepObjList);
-
- // Launch the helper task
- int Rc = __kmpc_omp_task_with_deps(nullptr, Gtid, Ptr, DepObjCount,
- DepObjs.data(), 0, nullptr);
-
- return Rc;
-}
-
EXTERN int omp_target_memcpy_async(void *Dst, const void *Src, size_t Length,
size_t DstOffset, size_t SrcOffset,
int DstDevice, int SrcDevice,
@@ -413,7 +377,8 @@ EXTERN int omp_target_memcpy_async(void *Dst, const void *Src, size_t Length,
Dst, Src, Length, DstOffset, SrcOffset, DstDevice, SrcDevice);
// Create and launch helper task
- int Rc = libomp_helper_memcpy_task_creation(Args, DepObjCount, DepObjList);
+ int Rc = libomp_helper_task_creation(Args, &libomp_target_memcpy_async_task,
+ DepObjCount, DepObjList);
DP("omp_target_memcpy_async returns %d\n", Rc);
return Rc;
@@ -510,7 +475,8 @@ EXTERN int omp_target_memcpy_rect_async(
DstDimensions, SrcDimensions, DstDevice, SrcDevice);
// Create and launch helper task
- int Rc = libomp_helper_memcpy_task_creation(Args, DepObjCount, DepObjList);
+ int Rc = libomp_helper_task_creation(Args, &libomp_target_memcpy_async_task,
+ DepObjCount, DepObjList);
DP("omp_target_memcpy_rect_async returns %d\n", Rc);
return Rc;
>From 012952ada089b623a7d361a00f74f787481ee9b0 Mon Sep 17 00:00:00 2001
From: Michael Klemm <michael.klemm at amd.com>
Date: Wed, 11 Oct 2023 16:43:57 +0200
Subject: [PATCH 7/7] Add a safety net against catastrophic failures of
omp_target_memset
---
openmp/libomptarget/src/api.cpp | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/openmp/libomptarget/src/api.cpp b/openmp/libomptarget/src/api.cpp
index ff51c73b58da162..0e989375cbe45b4 100644
--- a/openmp/libomptarget/src/api.cpp
+++ b/openmp/libomptarget/src/api.cpp
@@ -325,10 +325,18 @@ EXTERN void *omp_target_memset(void *Ptr, int ByteVal, size_t NumBytes,
// it to the GPU device.
int InitialDevice = omp_get_initial_device();
void *Shadow = omp_target_alloc(NumBytes, InitialDevice);
- (void)memset(Shadow, ByteVal, NumBytes);
- (void)omp_target_memcpy(Ptr, Shadow, NumBytes, 0, 0, DeviceNum,
- InitialDevice);
- (void)omp_target_free(Shadow, InitialDevice);
+ if (Shadow) {
+ (void)memset(Shadow, ByteVal, NumBytes);
+ (void)omp_target_memcpy(Ptr, Shadow, NumBytes, 0, 0, DeviceNum,
+ InitialDevice);
+ (void)omp_target_free(Shadow, InitialDevice);
+ } else {
+ // If the omp_target_alloc has failed, let's just not do anything.
+ // omp_target_memset does not have any good way to fail, so we
+ // simply avoid a catastrophic failure of the process for now.
+ DP("omp_target_memset failed to fill memory due to error with "
+ "omp_target_alloc");
+ }
}
DP("omp_target_memset returns %p\n", Ptr);
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