[OpenMP] Fix lone target exit data

[jdenny]

Summary

Without this patch, an omp target exit data before the runtime is
initialized produces a runtime error. This patch fixes that by
changing __tgt_target_data_end_mapper to call CheckDeviceAndCtors
like other many other runtime routines.

Discussed at
https://lists.llvm.org/pipermail/openmp-dev/2021-March/003920.html.

[grokos]

LGTM

openmp/libomptarget/src/interface.cpp

EXTERN void __tgt_target_data_end_mapper(ident_t *loc, int64_t device_id,
   }
 
   if (device_id == omp_get_initial_device()) {
     DP("Device is host (%" PRId64 "), returning as if offload is disabled\n",
        device_id);
     return;
   }
 
-  PM->RTLsMtx.lock();
-  size_t DevicesSize = PM->Devices.size();
-  PM->RTLsMtx.unlock();
-  if (DevicesSize <= (size_t)device_id) {
-    DP("Device ID  %" PRId64 " does not have a matching RTL.\n", device_id);
+  if (CheckDeviceAndCtors(device_id) != OFFLOAD_SUCCESS) {
+    DP("Failed to get device %" PRId64 " ready\n", device_id);
     HandleTargetOutcome(false, loc);
     return;
   }
 
   DeviceTy &Device = PM->Devices[device_id];
-  if (!Device.IsInit) {
-    DP("Uninit device: ignore");
-    HandleTargetOutcome(false, loc);
-    return;
-  }
 
   if (getInfoLevel() & OMP_INFOTYPE_KERNEL_ARGS)
     printKernelArguments(loc, device_id, arg_num, arg_sizes, arg_types,
                          arg_names, "Exiting OpenMP data region");
 #ifdef OMPTARGET_DEBUG
   for (int i = 0; i < arg_num; ++i) {
     DP("Entry %2d: Base=" DPxMOD ", Begin=" DPxMOD ", Size=%" PRId64
        ", Type=0x%" PRIx64 ", Name=%s\n",

openmp/libomptarget/test/offloading/lone_target_exit_data.c

+// Check that a target exit data directive behaves correctly when the runtime
+// has not yet been initialized.
+
+// RUN: %libomptarget-compile-run-and-check-aarch64-unknown-linux-gnu
+// RUN: %libomptarget-compile-run-and-check-powerpc64-ibm-linux-gnu
+// RUN: %libomptarget-compile-run-and-check-powerpc64le-ibm-linux-gnu
+// RUN: %libomptarget-compile-run-and-check-x86_64-pc-linux-gnu
+// RUN: %libomptarget-compile-run-and-check-nvptx64-nvidia-cuda
+
+#include <stdio.h>
+
+int main() {
+  // CHECK: x = 98
+  int x = 98;
+  #pragma omp target exit data map(from:x)
+  printf("x = %d\n", x);
+  return 0;
+}