[OPENMP]Do not allow threadprivates as base for array-like reduction.

[ABataev]

Summary

The base must be shared between the threads, threadprivates are not
allowed to be bases for array-like reductions.

[ABataev]

Rebase

[ABataev]

Rebase

[ABataev]

Rebase

[ABataev]

Rebase

[jdoerfert]

LGTM

clang/lib/Sema/SemaOpenMP.cpp

if (!ASE && !OASE) {
         if (DVar.CKind != OMPC_shared) {
           S.Diag(ELoc, diag::err_omp_required_access)
               << getOpenMPClauseName(OMPC_reduction)
               << getOpenMPClauseName(OMPC_shared);
           reportOriginalDsa(S, Stack, D, DVar);
           continue;
         }
       }
+    } else {
+      // Threadprivates cannot be shared between threads, so dignose if the base
+      // is a threadprivate variable.
+      DSAStackTy::DSAVarData DVar = Stack->getTopDSA(D, /*FromParent=*/false);
+      if (DVar.CKind == OMPC_threadprivate) {
+        S.Diag(ELoc, diag::err_omp_wrong_dsa)
+            << getOpenMPClauseName(DVar.CKind)
+            << getOpenMPClauseName(OMPC_reduction);
+        reportOriginalDsa(S, Stack, D, DVar);
+        continue;
+      }
     }
 
     // Try to find 'declare reduction' corresponding construct before using
     // builtin/overloaded operators.
     CXXCastPath BasePath;
     ExprResult DeclareReductionRef = buildDeclareReductionRef(
         S, ELoc, ERange, Stack->getCurScope(), ReductionIdScopeSpec,
         ReductionId, Type, BasePath, IR == ER ? nullptr : *IR);

clang/test/OpenMP/parallel_reduction_messages.cpp

 
 public:
   S6() : a(6) {}
   operator int() { return 6; }
 } o;
 
 S3 h, k;
 #pragma omp threadprivate(h) // expected-note 2 {{defined as threadprivate or thread local}}
+int *gptr;
+#pragma omp threadprivate(gptr) // expected-note {{defined as threadprivate or thread local}}
 
 template <class T>       // expected-note {{declared here}}
 T tmain(T argc) {
   const T d = T();       // expected-note 4 {{'d' defined here}}
   const T da[5] = {T()}; // expected-note 2 {{'da' defined here}}
   T qa[5] = {T()};
   T i, z;
   T &j = i;                    // expected-note 4 {{'j' defined here}}
#pragma omp for reduction(- : fl)
   for (int i = 0; i < 10; ++i)
 #pragma omp parallel reduction(+ : fl)
     foo();
   static int m;
 #pragma omp parallel reduction(+ : m) // OK
   m++;
 #pragma omp parallel reduction(task, + : m) // omp45-error 2 {{expected expression}} omp45-warning {{missing ':' after reduction identifier - ignoring}}
   m++;
+#pragma omp parallel reduction(+:gptr[:argc]) // expected-error {{threadprivate or thread local variable cannot be reduction}}
+  ;
 
   return tmain(argc) + tmain(fl); // expected-note {{in instantiation of function template specialization 'tmain<int>' requested here}} expected-note {{in instantiation of function template specialization 'tmain<float>' requested here}}
 }