[llvm] [OpenMP][Offload] Handle `present/to/from` when a different entry did `alloc/delete`. (PR #165494)

[Robert Imschweiler via llvm-commits]

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@@ -0,0 +1,48 @@
+// RUN: %libomptarget-compile-generic
+// RUN: %libomptarget-run-generic 2>&1 \
+// RUN: | %fcheck-generic -check-prefix=CHECK
+// RUN: env LIBOMPTARGET_DEBUG=1 %libomptarget-run-generic 2>&1 \
+// RUN: | %fcheck-generic -check-prefix=DEBUG
+// REQUIRES: libomptarget-debug
+
+// The "present" check should pass on the "target" construct (2),
+// and there should be no "to" transfer, because the pointee "x" is already
+// present (because of (1)).
+// However, there should be a "from" transfer at the end of (2) because of the
+// "delete" on the mapper.
+
+// FIXME: This currently fails, but should start passing once ATTACH-style maps
+// are enabled for mappers (#166874). UNSUPPORTED: true
+
+#include <stdio.h>
+
+typedef struct {
+  int *p;
+  int *q;
+} S;
+#pragma omp declare mapper(my_mapper : S s) map(alloc : s.p)                   \
+    map(alloc, present : s.p[0 : 10]) map(delete : s.q[ : ])                   \
+    map(from : s.p[0 : 10]) map(to : s.p[0 : 10]) map(alloc : s.p[0 : 10])
+
+S s1;
+int main() {
+  int x[10];
+  x[1] = 111;
+  s1.q = s1.p = &x[0];
+
+#pragma omp target data map(alloc : x) // (1)
+  {
+// DEBUG-NOT: omptarget --> Moving {{.*}} bytes (hst:0x{{.*}}) -> (tgt:0x{{.*}})
+#pragma omp target map(mapper(my_mapper), tofrom : s1) // (2)
+    {
+      // NOTE: It's ok for this to be 111 under "unified_shared_memory"
+      printf("%d\n", s1.p[1]); // CHECK-NOT: 111
+      s1.p[1] = 222;
+    }
+    printf("%d\n", s1.p[1]); // CHECK: 222
+  }
+  // clang-format off
+  // DEBUG: omptarget --> Found skipped FROM entry: HstPtr=0x[[#%x,HOST_ADDR:]] size=[[#%u,SIZE:]] within region being deleted
----------------
ro-i wrote:

```suggestion
  // DEBUG: omptarget --> Found skipped FROM entry: HstPtr=0x[[#%x,HOST_ADDR:]] size=[[#%u,SIZE:]] within region being released
```
since you updated the wording

https://github.com/llvm/llvm-project/pull/165494