[OpenMP] Fix `target data` exit for array extension

[jdenny]

Summary

For example:

#pragma omp target data map(tofrom:arr[0:100])
{
  #pragma omp target exit data map(delete:arr[0:100])
  #pragma omp target enter data map(alloc:arr[98:2])
}

Without this patch, the transfer at the end of the target data region
is broken and fails depending on the target device. According to my
read of the spec, the transfer shouldn't even be attempted because
arr[0:100] isn't (fully) present there. To fix that, this patch
makes DeviceTy::getTgtPtrBegin return null for this case.

[grokos]

Looks good.

[jdenny]

openmp/libomptarget/src/omptarget.cpp

509

Ah, I broke reference count decrements for implicit mappings. I think it should be true -> !IsImplicit. I'll work on another patch.

openmp/libomptarget/src/omptarget.cpp

for (int32_t I = ArgNum - 1; I >= 0; --I) {
     bool UpdateRef = !(ArgTypes[I] & OMP_TGT_MAPTYPE_MEMBER_OF) ||
                      (ArgTypes[I] & OMP_TGT_MAPTYPE_PTR_AND_OBJ);
     bool ForceDelete = ArgTypes[I] & OMP_TGT_MAPTYPE_DELETE;
     bool HasCloseModifier = ArgTypes[I] & OMP_TGT_MAPTYPE_CLOSE;
     bool HasPresentModifier = ArgTypes[I] & OMP_TGT_MAPTYPE_PRESENT;
 
     // If PTR_AND_OBJ, HstPtrBegin is address of pointee
     void *TgtPtrBegin = Device.getTgtPtrBegin(HstPtrBegin, DataSize, IsLast,
-                                              UpdateRef, IsHostPtr);
+                                              UpdateRef, IsHostPtr,
+                                              /*MustContain=*/true);
     if (!TgtPtrBegin && (DataSize || HasPresentModifier)) {
       DP("Mapping does not exist (%s)\n",
          (HasPresentModifier ? "'present' map type modifier" : "ignored"));
       if (HasPresentModifier) {
         // This should be an error upon entering an "omp target exit data".  It
         // should not be an error upon exiting an "omp target data" or "omp
         // target".  For "omp target data", Clang thus doesn't include present
         // modifiers for end calls.  For "omp target", we have not found a valid

openmp/libomptarget/test/mapping/target_data_array_extension_at_exit.c

+// --------------------------------------------------
+// Check extends before
+// --------------------------------------------------
+
+// RUN: %libomptarget-compile-aarch64-unknown-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=BEFORE
+// RUN: %libomptarget-run-aarch64-unknown-linux-gnu 2>&1 \
+// RUN: | %fcheck-aarch64-unknown-linux-gnu
+
+// RUN: %libomptarget-compile-powerpc64-ibm-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=BEFORE
+// RUN: %libomptarget-run-powerpc64-ibm-linux-gnu 2>&1 \
+// RUN: | %fcheck-powerpc64-ibm-linux-gnu
+
+// RUN: %libomptarget-compile-powerpc64le-ibm-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=BEFORE
+// RUN: %libomptarget-run-powerpc64le-ibm-linux-gnu 2>&1 \
+// RUN: | %fcheck-powerpc64le-ibm-linux-gnu
+
+// RUN: %libomptarget-compile-x86_64-pc-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=BEFORE
+// XUN: %libomptarget-run-x86_64-pc-linux-gnu 2>&1 \
+// XUN: | %fcheck-x86_64-pc-linux-gnu
+
+// --------------------------------------------------
+// Check extends after
+// --------------------------------------------------
+
+// RUN: %libomptarget-compile-aarch64-unknown-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=AFTER
+// RUN: %libomptarget-run-aarch64-unknown-linux-gnu 2>&1 \
+// RUN: | %fcheck-aarch64-unknown-linux-gnu
+
+// RUN: %libomptarget-compile-powerpc64-ibm-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=AFTER
+// RUN: %libomptarget-run-powerpc64-ibm-linux-gnu 2>&1 \
+// RUN: | %fcheck-powerpc64-ibm-linux-gnu
+
+// RUN: %libomptarget-compile-powerpc64le-ibm-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=AFTER
+// RUN: %libomptarget-run-powerpc64le-ibm-linux-gnu 2>&1 \
+// RUN: | %fcheck-powerpc64le-ibm-linux-gnu
+
+// RUN: %libomptarget-compile-x86_64-pc-linux-gnu \
+// RUN:   -fopenmp-version=51 -DEXTENDS=AFTER
+// RUN: %libomptarget-run-x86_64-pc-linux-gnu 2>&1 \
+// RUN: | %fcheck-x86_64-pc-linux-gnu
+
+// END.
+
+#include <stdio.h>
+
+#define BEFORE 0
+#define AFTER  1
+
+#define SIZE 100
+
+#if EXTENDS == BEFORE
+# define SMALL_BEG (SIZE-2)
+# define SMALL_END SIZE
+# define LARGE_BEG 0
+# define LARGE_END SIZE
+#elif EXTENDS == AFTER
+# define SMALL_BEG 0
+# define SMALL_END 2
+# define LARGE_BEG 0
+# define LARGE_END SIZE
+#else
+# error EXTENDS undefined
+#endif
+
+#define SMALL SMALL_BEG:(SMALL_END-SMALL_BEG)
+#define LARGE LARGE_BEG:(LARGE_END-LARGE_BEG)
+
+void check_not_present() {
+  int arr[SIZE];
+
+  for (int i = 0; i < SIZE; ++i)
+    arr[i] = 99;
+
+  // CHECK-LABEL: checking not present
+  fprintf(stderr, "checking not present\n");
+
+  // arr[LARGE] isn't (fully) present at the end of the target data region, so
+  // the device-to-host transfer should not be performed, or it might fail.
+#pragma omp target data map(tofrom: arr[LARGE])
+  {
+#pragma omp target exit data map(delete: arr[LARGE])
+#pragma omp target enter data map(alloc: arr[SMALL])
+#pragma omp target map(alloc: arr[SMALL])
+    for (int i = SMALL_BEG; i < SMALL_END; ++i)
+      arr[i] = 88;
+  }
+
+  // CHECK-NOT: Libomptarget
+  // CHECK-NOT: error
+  for (int i = 0; i < SIZE; ++i) {
+    if (arr[i] != 99)
+      fprintf(stderr, "error: arr[%d]=%d\n", i, arr[i]);
+  }
+}
+
+void check_is_present() {
+  int arr[SIZE];
+
+  for (int i = 0; i < SIZE; ++i)
+    arr[i] = 99;
+
+  // CHECK-LABEL: checking is present
+  fprintf(stderr, "checking is present\n");
+
+  // arr[SMALL] is (fully) present at the end of the target data region, and the
+  // device-to-host transfer should be performed only for it even though more
+  // of the array is then present.
+#pragma omp target data map(tofrom: arr[SMALL])
+  {
+#pragma omp target exit data map(delete: arr[SMALL])
+#pragma omp target enter data map(alloc: arr[LARGE])
+#pragma omp target map(alloc: arr[LARGE])
+    for (int i = LARGE_BEG; i < LARGE_END; ++i)
+      arr[i] = 88;
+  }
+
+  // CHECK-NOT: Libomptarget
+  // CHECK-NOT: error
+  for (int i = 0; i < SIZE; ++i) {
+    if (SMALL_BEG <= i && i < SMALL_END) {
+      if (arr[i] != 88)
+        fprintf(stderr, "error: arr[%d]=%d\n", i, arr[i]);
+    } else if (arr[i] != 99) {
+      fprintf(stderr, "error: arr[%d]=%d\n", i, arr[i]);
+    }
+  }
+}
+
+int main() {
+  check_not_present();
+  check_is_present();
+  return 0;
+}