[Openmp-commits] [openmp] [Libomptarget] Fix Nvidia offloading hanging on dataRetrieve using RPC (PR #66817)

[Johannes Doerfert via Openmp-commits]

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@@ -0,0 +1,22 @@
+// RUN: %libomptarget-compile-run-and-check-generic
+
+// REQUIRES: libc
+
+#include <assert.h>
+#include <stdio.h>
+
+#pragma omp declare target to(stdout)
+
+int main() {
+  int r = 0;
+// CHECK: PASS
+#pragma omp target map(from : r)
+  { r = fwrite("PASS\n", 1, sizeof("PASS\n") - 1, stdout); }
+  assert(r == sizeof("PASS\n") - 1 && "Incorrect number of bytes written");
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jdoerfert wrote:

So, turns out the call is blocking, according to https://docs.nvidia.com/cuda/cuda-driver-api/api-sync-behavior.html#api-sync-behavior__memcpy-async rule synchronous 3.
The solution above seems sensible to me. 

https://github.com/llvm/llvm-project/pull/66817