[PATCH] D56430: Incorrect implicit data-sharing for nested tasks

[Sergi Mateo via Phabricator via cfe-commits]

smateo created this revision.
smateo added a reviewer: ABataev.
smateo added a project: OpenMP.
Herald added a subscriber: cfe-commits.

There is a minor issue in how the implicit data-sharings for nested tasks are computed.

For the following example:

  int x;
  #pragma omp task shared(x)
  #pragma omp task
  x++;

We compute an implicit data-sharing of shared for `x` in the second task although I think that it should be firstprivate. Below you can find the part of the OpenMP spec that covers this example:

- // In a task generating construct, if no default clause is present, a variable for which the data-sharing attribute is not determined by the rules above and that in the enclosing context is determined to be shared by all implicit tasks bound to the current team is shared.//
- //In a task generating construct, if no default clause is present, a variable for which the data-sharing attribute is not determined by the rules above is firstprivate.//

Since each implicit-task has its own copy of `x`, we shouldn't apply the first rule.


Repository:
  rC Clang

https://reviews.llvm.org/D56430

Files:
  lib/Sema/SemaOpenMP.cpp
  test/OpenMP/task_messages.cpp


Index: test/OpenMP/task_messages.cpp
===================================================================
--- test/OpenMP/task_messages.cpp
+++ test/OpenMP/task_messages.cpp
@@ -8,7 +8,7 @@
 #pragma omp task // expected-error {{unexpected OpenMP directive '#pragma omp task'}}
 
 class S {
-  S(const S &s) { a = s.a + 12; } // expected-note 14 {{implicitly declared private here}}
+  S(const S &s) { a = s.a + 12; } // expected-note 16 {{implicitly declared private here}}
   int a;
 
 public:
@@ -51,6 +51,15 @@
   ++a; // expected-error {{calling a private constructor of class 'S'}}
 #pragma omp task default(shared)
 #pragma omp task
+  // expected-error at +1 {{calling a private constructor of class 'S'}}
+  ++a;
+#pragma omp parallel shared(a)
+#pragma omp task
+#pragma omp task
+  ++a;
+#pragma omp parallel shared(a)
+#pragma omp task default(shared)
+#pragma omp task
   ++a;
 #pragma omp task
 #pragma omp parallel
@@ -205,6 +214,15 @@
   ++sa; // expected-error {{calling a private constructor of class 'S'}}
 #pragma omp task default(shared)
 #pragma omp task
+  // expected-error at +1 {{calling a private constructor of class 'S'}}
+  ++sa;
+#pragma omp parallel shared(sa)
+#pragma omp task
+#pragma omp task
+  ++sa;
+#pragma omp parallel shared(sa)
+#pragma omp task default(shared)
+#pragma omp task
   ++sa;
 #pragma omp task
 #pragma omp parallel
Index: lib/Sema/SemaOpenMP.cpp
===================================================================
--- lib/Sema/SemaOpenMP.cpp
+++ lib/Sema/SemaOpenMP.cpp
@@ -676,9 +676,13 @@
   }
 
 };
+
+bool isParallelRegion(OpenMPDirectiveKind DKind) {
+  return isOpenMPParallelDirective(DKind) || isOpenMPTeamsDirective(DKind);
+}
+
 bool isParallelOrTaskRegion(OpenMPDirectiveKind DKind) {
-  return isOpenMPParallelDirective(DKind) || isOpenMPTaskingDirective(DKind) ||
-         isOpenMPTeamsDirective(DKind) || DKind == OMPD_unknown;
+  return isParallelRegion(DKind) || isOpenMPTaskingDirective(DKind) || DKind == OMPD_unknown;
 }
 
 } // namespace
@@ -819,7 +823,7 @@
           DVar.CKind = OMPC_firstprivate;
           return DVar;
         }
-      } while (I != E && !isParallelOrTaskRegion(I->Directive));
+      } while (I != E && !isParallelRegion(I->Directive));
       DVar.CKind =
           (DVarTemp.CKind == OMPC_unknown) ? OMPC_firstprivate : OMPC_shared;
       return DVar;


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