[OpenMP] Introduce the keepAlive function into the old device RT

jdoerfert · jdoerfert · commit ab9f3f5d25dc · 2021-11-04T17:54:56.000-05:00
Reviewed By: ye-luo Differential Revision: https://reviews.llvm.org/D113110
diff --git a/openmp/libomptarget/deviceRTLs/common/src/support.cu b/openmp/libomptarget/deviceRTLs/common/src/support.cu
@@ -226,4 +226,14 @@ void __kmp_invoke_microtask(kmp_int32 global_tid, kmp_int32 bound_tid, void *fn,
   }
 }
 
+namespace _OMP {
+/// Helper to keep code alive without introducing a performance penalty.
+__attribute__((used, weak, optnone)) void keepAlive() {
+  __kmpc_get_hardware_thread_id_in_block();
+  __kmpc_get_hardware_num_threads_in_block();
+  __kmpc_barrier_simple_spmd(nullptr, 0);
+  __kmpc_barrier_simple_generic(nullptr, 0);
+}
+} // namespace _OMP
+
 #pragma omp end declare target

Original file line number	Diff line number	Diff line change
`@@ -226,4 +226,14 @@ void __kmp_invoke_microtask(kmp_int32 global_tid, kmp_int32 bound_tid, void *fn,`
`226`	`226`	`}`
`227`	`227`	`}`
`228`	`228`
	`229`	`+namespace _OMP {`
	`230`	`+/// Helper to keep code alive without introducing a performance penalty.`
	`231`	`+__attribute__((used, weak, optnone)) void keepAlive() {`
	`232`	`+ __kmpc_get_hardware_thread_id_in_block();`
	`233`	`+ __kmpc_get_hardware_num_threads_in_block();`
	`234`	`+ __kmpc_barrier_simple_spmd(nullptr, 0);`
	`235`	`+ __kmpc_barrier_simple_generic(nullptr, 0);`
	`236`	`+}`
	`237`	`+} // namespace _OMP`
	`238`	`+`
`229`	`239`	`#pragma omp end declare target`