[Openmp-commits] [openmp] 479e335 - [OpenMP] Handle function calls from `libomp` to `libomptarget` correctly

[Shilei Tian via Openmp-commits]

Author: Shilei Tian
Date: 2023-05-01T18:19:16-04:00
New Revision: 479e335fc37c06767654141358ea076ac066de11

URL: https://github.com/llvm/llvm-project/commit/479e335fc37c06767654141358ea076ac066de11
DIFF: https://github.com/llvm/llvm-project/commit/479e335fc37c06767654141358ea076ac066de11.diff

LOG: [OpenMP] Handle function calls from `libomp` to `libomptarget` correctly

D132005 introduced function calls from `libomp` to `libomptarget` if offloading
is enabled. However, the external function declaration may not always work. For
example, it causes a link error on macOS. Currently it is guarded properly by
a macro, but in order to get OpenMP target offloading working on macOS, it has
to be handled correctly. This patch applies the same idea of how we support
target memory extension by using function pointer indirect call for that function.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D149557

Added: 
    

Modified: 
    openmp/runtime/src/kmp.h
    openmp/runtime/src/kmp_runtime.cpp
    openmp/runtime/src/kmp_tasking.cpp

Removed: 
    


################################################################################
diff  --git a/openmp/runtime/src/kmp.h b/openmp/runtime/src/kmp.h
index 43e723fa7387b..bd50d58f0fdcb 100644
--- a/openmp/runtime/src/kmp.h
+++ b/openmp/runtime/src/kmp.h
@@ -1100,6 +1100,12 @@ extern void __kmp_init_target_mem();
 
 /* ------------------------------------------------------------------------ */
 
+#if ENABLE_LIBOMPTARGET
+extern void __kmp_init_target_task();
+#endif
+
+/* ------------------------------------------------------------------------ */
+
 #define KMP_UINT64_MAX                                                         \
   (~((kmp_uint64)1 << ((sizeof(kmp_uint64) * (1 << 3)) - 1)))
 

diff  --git a/openmp/runtime/src/kmp_runtime.cpp b/openmp/runtime/src/kmp_runtime.cpp
index 776160289981b..a0a72f163e7c5 100644
--- a/openmp/runtime/src/kmp_runtime.cpp
+++ b/openmp/runtime/src/kmp_runtime.cpp
@@ -553,6 +553,14 @@ static void __kmp_fini_allocator() { __kmp_fini_memkind(); }
 
 /* ------------------------------------------------------------------------ */
 
+#if ENABLE_LIBOMPTARGET
+static void __kmp_init_omptarget() {
+  __kmp_init_target_task();
+}
+#endif
+
+/* ------------------------------------------------------------------------ */
+
 #if KMP_DYNAMIC_LIB
 #if KMP_OS_WINDOWS
 
@@ -7041,6 +7049,11 @@ static void __kmp_do_serial_initialize(void) {
 
   __kmp_validate_locks();
 
+#if ENABLE_LIBOMPTARGET
+  /* Initialize functions from libomptarget */
+  __kmp_init_omptarget();
+#endif
+
   /* Initialize internal memory allocator */
   __kmp_init_allocator();
 

diff  --git a/openmp/runtime/src/kmp_tasking.cpp b/openmp/runtime/src/kmp_tasking.cpp
index 71922ed708001..f441b0e9ef673 100644
--- a/openmp/runtime/src/kmp_tasking.cpp
+++ b/openmp/runtime/src/kmp_tasking.cpp
@@ -22,8 +22,12 @@
 #endif
 
 #if ENABLE_LIBOMPTARGET
-// Declaration of synchronization function from libomptarget.
-extern "C" void __tgt_target_nowait_query(void **) KMP_WEAK_ATTRIBUTE_INTERNAL;
+static void (*tgt_target_nowait_query)(void **);
+
+void __kmp_init_target_task() {
+  *(void **)(&tgt_target_nowait_query) = KMP_DLSYM("__tgt_target_nowait_query");
+  KMP_ASSERT(tgt_target_nowait_query);
+}
 #endif
 
 /* forward declaration */
@@ -1805,7 +1809,7 @@ static void __kmp_invoke_task(kmp_int32 gtid, kmp_task_t *task,
       // If we have a valid target async handle, that means that we have already
       // executed the task routine once. We must query for the handle completion
       // instead of re-executing the routine.
-      __tgt_target_nowait_query(&taskdata->td_target_data.async_handle);
+      tgt_target_nowait_query(&taskdata->td_target_data.async_handle);
     } else
 #endif
     if (task->routine != NULL) {