OpenMP: Data-sharing attributes analysis and clause 'shared' (fixed test threadprivate_messages.cpp)

llvm-svn: 190183

3 files changed, 558 insertions, 13 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index a3b1bfa1c22..71d726f6195 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -90,7 +90,8 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
     NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
     CurrentInstantiationScope(0), TyposCorrected(0),
-    AnalysisWarnings(*this), CurScope(0), Ident_super(0), Ident___float128(0)
+    AnalysisWarnings(*this), VarDataSharingAttributesStack(0), CurScope(0),
+    Ident_super(0), Ident___float128(0)
 {
   TUScope = 0;
 
@@ -113,6 +114,9 @@ Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
                                           false, 0, false));
 
   FunctionScopes.push_back(new FunctionScopeInfo(Diags));
+
+  // Initilization of data sharing attributes stack for OpenMP
+  InitDataSharingAttributesStack();
 }
 
 void Sema::Initialize() {
@@ -199,6 +203,9 @@ Sema::~Sema() {
   // If Sema's ExternalSource is the multiplexer - we own it.
   if (isMultiplexExternalSource)
     delete ExternalSource;
+
+  // Destroys data sharing attributes stack for OpenMP
+  DestroyDataSharingAttributesStack();
 }
 
 /// makeUnavailableInSystemHeader - There is an error in the current
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 09ecfe09092..1048c5ad7bb 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -27,6 +27,325 @@
 #include "clang/Sema/ScopeInfo.h"
 using namespace clang;
 
+//===----------------------------------------------------------------------===//
+// Stack of data-sharing attributes for variables
+//===----------------------------------------------------------------------===//
+
+namespace {
+/// \brief Default data sharing attributes, which can be applied to directive.
+enum DefaultDataSharingAttributes {
+  DSA_unspecified = 0,   /// \brief Data sharing attribute not specified.
+  DSA_none = 1 << 0,     /// \brief Default data sharing attribute 'none'.
+  DSA_shared = 1 << 1    /// \brief Default data sharing attribute 'shared'.
+};
+
+/// \brief Stack for tracking declarations used in OpenMP directives and
+/// clauses and their data-sharing attributes.
+class DSAStackTy {
+public:
+  struct DSAVarData {
+    OpenMPDirectiveKind DKind;
+    OpenMPClauseKind CKind;
+    DeclRefExpr *RefExpr;
+    DSAVarData() : DKind(OMPD_unknown), CKind(OMPC_unknown), RefExpr(0) { }
+  };
+private:
+  struct DSAInfo {
+    OpenMPClauseKind Attributes;
+    DeclRefExpr *RefExpr;
+  };
+  typedef llvm::SmallDenseMap<VarDecl *, DSAInfo, 64> DeclSAMapTy;
+
+  struct SharingMapTy {
+    DeclSAMapTy SharingMap;
+    DefaultDataSharingAttributes DefaultAttr;
+    OpenMPDirectiveKind Directive;
+    DeclarationNameInfo DirectiveName;
+    Scope *CurScope;
+    SharingMapTy(OpenMPDirectiveKind DKind,
+                 const DeclarationNameInfo &Name,
+                 Scope *CurScope)
+      : SharingMap(), DefaultAttr(DSA_unspecified), Directive(DKind),
+        DirectiveName(Name), CurScope(CurScope) { }
+    SharingMapTy()
+      : SharingMap(), DefaultAttr(DSA_unspecified),
+        Directive(OMPD_unknown), DirectiveName(),
+        CurScope(0) { }
+  };
+
+  typedef SmallVector<SharingMapTy, 64> StackTy;
+
+  /// \brief Stack of used declaration and their data-sharing attributes.
+  StackTy Stack;
+  Sema &Actions;
+
+  typedef SmallVector<SharingMapTy, 8>::reverse_iterator reverse_iterator;
+
+  DSAVarData getDSA(StackTy::reverse_iterator Iter, VarDecl *D);
+public:
+  explicit DSAStackTy(Sema &S) : Stack(1), Actions(S) { }
+
+  void push(OpenMPDirectiveKind DKind, const DeclarationNameInfo &DirName,
+            Scope *CurScope) {
+    Stack.push_back(SharingMapTy(DKind, DirName, CurScope));
+  }
+
+  void pop() {
+    assert(Stack.size() > 1 && "Data-sharing attributes stack is empty!");
+    Stack.pop_back();
+  }
+
+  /// \brief Adds explicit data sharing attribute to the specified declaration.
+  void addDSA(VarDecl *D, DeclRefExpr *E, OpenMPClauseKind A);
+
+  /// \brief Checks if the variable is a local for OpenMP region.
+  bool isOpenMPLocal(VarDecl *D);
+
+  /// \brief Returns data sharing attributes from top of the stack for the
+  /// specified declaration.
+  DSAVarData getTopDSA(VarDecl *D);
+  /// \brief Returns data-sharing attributes for the specified declaration.
+  DSAVarData getImplicitDSA(VarDecl *D);
+
+  /// \brief Returns currently analyzed directive.
+  OpenMPDirectiveKind getCurrentDirective() const {
+    return Stack.back().Directive;
+  }
+
+  /// \brief Set default data sharing attribute to none.
+  void setDefaultDSANone() { Stack.back().DefaultAttr = DSA_none; }
+  /// \brief Set default data sharing attribute to shared.
+  void setDefaultDSAShared() { Stack.back().DefaultAttr = DSA_shared; }
+
+  DefaultDataSharingAttributes getDefaultDSA() const {
+    return Stack.back().DefaultAttr;
+  }
+
+  Scope *getCurScope() { return Stack.back().CurScope; }
+};
+} // end anonymous namespace.
+
+DSAStackTy::DSAVarData DSAStackTy::getDSA(StackTy::reverse_iterator Iter,
+                                          VarDecl *D) {
+  DSAVarData DVar;
+  if (Iter == Stack.rend() - 1) {
+    // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+    // in a region but not in construct]
+    //  File-scope or namespace-scope variables referenced in called routines
+    //  in the region are shared unless they appear in a threadprivate
+    //  directive.
+    // TODO
+    if (!D->isFunctionOrMethodVarDecl())
+      DVar.CKind = OMPC_shared;
+
+    return DVar;
+  }
+  DVar.DKind = Iter->Directive;
+  // Explicitly specified attributes and local variables with predetermined
+  // attributes.
+  if (Iter->SharingMap.count(D)) {
+    DVar.RefExpr = Iter->SharingMap[D].RefExpr;
+    DVar.CKind = Iter->SharingMap[D].Attributes;
+    return DVar;
+  }
+
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, implicitly determined, p.1]
+  //  In a parallel or task construct, the data-sharing attributes of these
+  //  variables are determined by the default clause, if present.
+  switch (Iter->DefaultAttr) {
+  case DSA_shared:
+    DVar.CKind = OMPC_shared;
+    return DVar;
+  case DSA_none:
+    return DVar;
+  case DSA_unspecified:
+    // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+    // in a Construct, implicitly determined, p.2]
+    //  In a parallel construct, if no default clause is present, these
+    //  variables are shared.
+    if (DVar.DKind == OMPD_parallel) {
+      DVar.CKind = OMPC_shared;
+      return DVar;
+    }
+
+    // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+    // in a Construct, implicitly determined, p.4]
+    //  In a task construct, if no default clause is present, a variable that in
+    //  the enclosing context is determined to be shared by all implicit tasks
+    //  bound to the current team is shared.
+    // TODO
+    if (DVar.DKind == OMPD_task) {
+      DSAVarData DVarTemp;
+      for (StackTy::reverse_iterator I = Iter + 1,
+                                     EE = Stack.rend() - 1;
+           I != EE; ++I) {
+        // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+        // in a Construct, implicitly determined, p.6]
+        //  In a task construct, if no default clause is present, a variable
+        //  whose data-sharing attribute is not determined by the rules above is
+        //  firstprivate.
+        DVarTemp = getDSA(I, D);
+        if (DVarTemp.CKind != OMPC_shared) {
+          DVar.RefExpr = 0;
+          DVar.DKind = OMPD_task;
+          DVar.CKind = OMPC_unknown;
+          // TODO: should return OMPC_firstprivate
+          return DVar;
+        }
+        if (I->Directive == OMPD_parallel) break;
+      }
+      DVar.DKind = OMPD_task;
+      // TODO: Should return OMPC_firstprivate instead of OMPC_unknown.
+      DVar.CKind =
+        (DVarTemp.CKind == OMPC_unknown) ? OMPC_unknown : OMPC_shared;
+      return DVar;
+    }
+  }
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, implicitly determined, p.3]
+  //  For constructs other than task, if no default clause is present, these
+  //  variables inherit their data-sharing attributes from the enclosing
+  //  context.
+  return getDSA(Iter + 1, D);
+}
+
+void DSAStackTy::addDSA(VarDecl *D, DeclRefExpr *E, OpenMPClauseKind A) {
+  if (A == OMPC_threadprivate) {
+    Stack[0].SharingMap[D].Attributes = A;
+    Stack[0].SharingMap[D].RefExpr = E;
+  } else {
+    assert(Stack.size() > 1 && "Data-sharing attributes stack is empty");
+    Stack.back().SharingMap[D].Attributes = A;
+    Stack.back().SharingMap[D].RefExpr = E;
+  }
+}
+
+bool DSAStackTy::isOpenMPLocal(VarDecl *D) {
+  Scope *CurScope = getCurScope();
+  while (CurScope && !CurScope->isDeclScope(D))
+    CurScope = CurScope->getParent();
+  while (CurScope && !CurScope->isOpenMPDirectiveScope())
+    CurScope = CurScope->getParent();
+  bool isOpenMPLocal = !!CurScope;
+  if (!isOpenMPLocal) {
+    CurScope = getCurScope();
+    while (CurScope && !CurScope->isOpenMPDirectiveScope())
+      CurScope = CurScope->getParent();
+    isOpenMPLocal =
+      CurScope &&
+      isa<CapturedDecl>(D->getDeclContext()) &&
+      static_cast<DeclContext *>(
+        CurScope->getFnParent()->getEntity())->Encloses(D->getDeclContext());
+  }
+  return isOpenMPLocal;
+}
+
+DSAStackTy::DSAVarData DSAStackTy::getTopDSA(VarDecl *D) {
+  DSAVarData DVar;
+
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, predetermined, p.1]
+  //  Variables appearing in threadprivate directives are threadprivate.
+  if (D->getTLSKind() != VarDecl::TLS_None) {
+    DVar.CKind = OMPC_threadprivate;
+    return DVar;
+  }
+  if (Stack[0].SharingMap.count(D)) {
+    DVar.RefExpr = Stack[0].SharingMap[D].RefExpr;
+    DVar.CKind = OMPC_threadprivate;
+    return DVar;
+  }
+
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, predetermined, p.1]
+  // Variables with automatic storage duration that are declared in a scope
+  // inside the construct are private.
+  if (isOpenMPLocal(D) && D->isLocalVarDecl() &&
+      (D->getStorageClass() == SC_Auto ||
+       D->getStorageClass() == SC_None)) {
+    DVar.CKind = OMPC_private;
+    return DVar;
+  }
+
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, predetermined, p.4]
+  //  Static data memebers are shared.
+  if (D->isStaticDataMember()) {
+    // Variables with const-qualified type having no mutable member may be
+    // listed in a firstprivate clause, even if they are static data members.
+    // TODO:
+    DVar.CKind = OMPC_shared;
+    return DVar;
+  }
+
+  QualType Type = D->getType().getNonReferenceType().getCanonicalType();
+  bool IsConstant = Type.isConstant(Actions.getASTContext());
+  while (Type->isArrayType()) {
+    QualType ElemType = cast<ArrayType>(Type.getTypePtr())->getElementType();
+    Type = ElemType.getNonReferenceType().getCanonicalType();
+  }
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, predetermined, p.6]
+  //  Variables with const qualified type having no mutable member are
+  //  shared.
+  CXXRecordDecl *RD = Actions.getLangOpts().CPlusPlus ?
+                                Type->getAsCXXRecordDecl() : 0;
+  if (IsConstant &&
+      !(Actions.getLangOpts().CPlusPlus && RD && RD->hasMutableFields())) {
+    // Variables with const-qualified type having no mutable member may be
+    // listed in a firstprivate clause, even if they are static data members.
+    // TODO
+    DVar.CKind = OMPC_shared;
+    return DVar;
+  }
+
+  // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+  // in a Construct, C/C++, predetermined, p.7]
+  //  Variables with static storage duration that are declared in a scope
+  //  inside the construct are shared.
+  if (isOpenMPLocal(D) && D->isStaticLocal()) {
+    DVar.CKind = OMPC_shared;
+    return DVar;
+  }
+
+  // Explicitly specified attributes and local variables with predetermined
+  // attributes.
+  if (Stack.back().SharingMap.count(D)) {
+    DVar.RefExpr = Stack.back().SharingMap[D].RefExpr;
+    DVar.CKind = Stack.back().SharingMap[D].Attributes;
+  }
+
+  return DVar;
+}
+
+DSAStackTy::DSAVarData DSAStackTy::getImplicitDSA(VarDecl *D) {
+  return getDSA(Stack.rbegin() + 1, D);
+}
+
+void Sema::InitDataSharingAttributesStack() {
+  VarDataSharingAttributesStack = new DSAStackTy(*this);
+}
+
+#define DSAStack static_cast<DSAStackTy *>(VarDataSharingAttributesStack)
+
+void Sema::DestroyDataSharingAttributesStack() {
+  delete DSAStack;
+}
+
+void Sema::StartOpenMPDSABlock(OpenMPDirectiveKind DKind,
+                               const DeclarationNameInfo &DirName,
+                               Scope *CurScope) {
+  DSAStack->push(DKind, DirName, CurScope);
+  PushExpressionEvaluationContext(PotentiallyEvaluated);
+}
+
+void Sema::EndOpenMPDSABlock(Stmt *CurDirective) {
+  DSAStack->pop();
+  DiscardCleanupsInEvaluationContext();
+  PopExpressionEvaluationContext();
+}
+
 namespace {
 
 class VarDeclFilterCCC : public CorrectionCandidateCallback {
@@ -130,6 +449,7 @@ ExprResult Sema::ActOnOpenMPIdExpression(Scope *CurScope,
 
   QualType ExprType = VD->getType().getNonReferenceType();
   ExprResult DE = BuildDeclRefExpr(VD, ExprType, VK_RValue, Id.getLoc());
+  DSAStack->addDSA(VD, cast<DeclRefExpr>(DE.get()), OMPC_threadprivate);
   return DE;
 }
 
@@ -192,12 +512,93 @@ OMPThreadPrivateDecl *Sema::CheckOMPThreadPrivateDecl(
                                                Loc, Vars);
 }
 
+namespace {
+class DSAAttrChecker : public StmtVisitor<DSAAttrChecker, void> {
+  DSAStackTy *Stack;
+  Sema &Actions;
+  bool ErrorFound;
+  CapturedStmt *CS;
+public:
+  void VisitDeclRefExpr(DeclRefExpr *E) {
+    if(VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) {
+      if (VD->isImplicit() && VD->hasAttr<UnusedAttr>()) return;
+      // Skip internally declared variables.
+      if (VD->isLocalVarDecl() && !CS->capturesVariable(VD)) return;
+
+      SourceLocation ELoc = E->getExprLoc();
+
+      OpenMPDirectiveKind DKind = Stack->getCurrentDirective();
+      DSAStackTy::DSAVarData DVar = Stack->getTopDSA(VD);
+      if (DVar.CKind != OMPC_unknown) {
+        if (DKind == OMPD_task && DVar.CKind != OMPC_shared &&
+            DVar.CKind != OMPC_threadprivate && !DVar.RefExpr)
+          // TODO: should be marked as firstprivate.
+          ;
+        return;
+      }
+      // The default(none) clause requires that each variable that is referenced
+      // in the construct, and does not have a predetermined data-sharing
+      // attribute, must have its data-sharing attribute explicitly determined
+      // by being listed in a data-sharing attribute clause.
+      if (DVar.CKind == OMPC_unknown && Stack->getDefaultDSA() == DSA_none &&
+          (DKind == OMPD_parallel || DKind == OMPD_task)) {
+        ErrorFound = true;
+        Actions.Diag(ELoc, diag::err_omp_no_dsa_for_variable) << VD;
+        return;
+      }
+
+      // OpenMP [2.9.3.6, Restrictions, p.2]
+      //  A list item that appears in a reduction clause of the innermost
+      //  enclosing worksharing or parallel construct may not be accessed in an
+      //  explicit task.
+      // TODO:
+
+      // Define implicit data-sharing attributes for task.
+      DVar = Stack->getImplicitDSA(VD);
+      if (DKind == OMPD_task && DVar.CKind != OMPC_shared) {
+        // TODO: should be marked as firstprivate.
+      }
+    }
+  }
+  void VisitOMPExecutableDirective(OMPExecutableDirective *S) {
+    for (ArrayRef<OMPClause *>::iterator I = S->clauses().begin(),
+                                         E = S->clauses().end();
+         I != E; ++I)
+      if (OMPClause *C = *I)
+        for (StmtRange R = C->children(); R; ++R)
+          if (Stmt *Child = *R)
+            Visit(Child);
+  }
+  void VisitStmt(Stmt *S) {
+    for (Stmt::child_iterator I = S->child_begin(), E = S->child_end();
+         I != E; ++I)
+      if (Stmt *Child = *I)
+        if (!isa<OMPExecutableDirective>(Child))
+          Visit(Child);
+    }
+
+  bool isErrorFound() { return ErrorFound; }
+
+  DSAAttrChecker(DSAStackTy *S, Sema &Actions, CapturedStmt *CS)
+    : Stack(S), Actions(Actions), ErrorFound(false), CS(CS) { }
+};
+}
+
 StmtResult Sema::ActOnOpenMPExecutableDirective(OpenMPDirectiveKind Kind,
                                                 ArrayRef<OMPClause *> Clauses,
                                                 Stmt *AStmt,
                                                 SourceLocation StartLoc,
                                                 SourceLocation EndLoc) {
+  assert(AStmt && isa<CapturedStmt>(AStmt) && "Captured statement expected");
+
   StmtResult Res = StmtError();
+
+  // Check default data sharing attributes for referenced variables.
+  DSAAttrChecker DSAChecker(DSAStack, *this, cast<CapturedStmt>(AStmt));
+  DSAChecker.Visit(cast<CapturedStmt>(AStmt)->getCapturedStmt());
+  if (DSAChecker.isErrorFound())
+    return StmtError();
+
   switch (Kind) {
   case OMPD_parallel:
     Res = ActOnOpenMPParallelDirective(Clauses, AStmt, StartLoc, EndLoc);
@@ -231,11 +632,12 @@ OMPClause *Sema::ActOnOpenMPSimpleClause(OpenMPClauseKind Kind,
   OMPClause *Res = 0;
   switch (Kind) {
   case OMPC_default:
-    Res = ActOnOpenMPDefaultClause(
-                             static_cast<OpenMPDefaultClauseKind>(Argument),
-                             ArgumentLoc, StartLoc, LParenLoc, EndLoc);
+    Res =
+      ActOnOpenMPDefaultClause(static_cast<OpenMPDefaultClauseKind>(Argument),
+                               ArgumentLoc, StartLoc, LParenLoc, EndLoc);
     break;
   case OMPC_private:
+  case OMPC_shared:
   case OMPC_threadprivate:
   case OMPC_unknown:
   case NUM_OPENMP_CLAUSES:
@@ -272,6 +674,16 @@ OMPClause *Sema::ActOnOpenMPDefaultClause(OpenMPDefaultClauseKind Kind,
       << Values << getOpenMPClauseName(OMPC_default);
     return 0;
   }
+  switch (Kind) {
+  case OMPC_DEFAULT_none:
+    DSAStack->setDefaultDSANone();
+    break;
+  case OMPC_DEFAULT_shared:
+    DSAStack->setDefaultDSAShared();
+    break;
+  default:
+    break;
+  }
   return new (Context) OMPDefaultClause(Kind, KindKwLoc, StartLoc, LParenLoc,
                                         EndLoc);
 }
@@ -286,6 +698,9 @@ OMPClause *Sema::ActOnOpenMPVarListClause(OpenMPClauseKind Kind,
   case OMPC_private:
     Res = ActOnOpenMPPrivateClause(VarList, StartLoc, LParenLoc, EndLoc);
     break;
+  case OMPC_shared:
+    Res = ActOnOpenMPSharedClause(VarList, StartLoc, LParenLoc, EndLoc);
+    break;
   case OMPC_default:
   case OMPC_threadprivate:
   case OMPC_unknown:
@@ -396,6 +811,29 @@ OMPClause *Sema::ActOnOpenMPPrivateClause(ArrayRef<Expr *> VarList,
       }
     }
 
+    // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+    // in a Construct]
+    //  Variables with the predetermined data-sharing attributes may not be
+    //  listed in data-sharing attributes clauses, except for the cases
+    //  listed below. For these exceptions only, listing a predetermined
+    //  variable in a data-sharing attribute clause is allowed and overrides
+    //  the variable's predetermined data-sharing attributes.
+    DSAStackTy::DSAVarData DVar = DSAStack->getTopDSA(VD);
+    if (DVar.CKind != OMPC_unknown && DVar.CKind != OMPC_private) {
+      Diag(ELoc, diag::err_omp_wrong_dsa)
+         << getOpenMPClauseName(DVar.CKind)
+         << getOpenMPClauseName(OMPC_private);
+      if (DVar.RefExpr) {
+        Diag(DVar.RefExpr->getExprLoc(), diag::note_omp_explicit_dsa)
+             << getOpenMPClauseName(DVar.CKind);
+      } else {
+        Diag(VD->getLocation(), diag::note_omp_predetermined_dsa)
+             << getOpenMPClauseName(DVar.CKind);
+      }
+      continue;
+    }
+
+    DSAStack->addDSA(VD, DE, OMPC_private);
     Vars.push_back(DE);
   }
 
@@ -404,3 +842,65 @@ OMPClause *Sema::ActOnOpenMPPrivateClause(ArrayRef<Expr *> VarList,
   return OMPPrivateClause::Create(Context, StartLoc, LParenLoc, EndLoc, Vars);
 }
 
+OMPClause *Sema::ActOnOpenMPSharedClause(ArrayRef<Expr *> VarList,
+                                         SourceLocation StartLoc,
+                                         SourceLocation LParenLoc,
+                                         SourceLocation EndLoc) {
+  SmallVector<Expr *, 8> Vars;
+  for (ArrayRef<Expr *>::iterator I = VarList.begin(), E = VarList.end();
+       I != E; ++I) {
+    if (*I && isa<DependentScopeDeclRefExpr>(*I)) {
+      // It will be analyzed later.
+      Vars.push_back(*I);
+      continue;
+    }
+
+    SourceLocation ELoc = (*I)->getExprLoc();
+    // OpenMP [2.1, C/C++]
+    //  A list item is a variable name.
+    // OpenMP  [2.9.3.4, Restrictions, p.1]
+    //  A variable that is part of another variable (as an array or
+    //  structure element) cannot appear in a private clause.
+    DeclRefExpr *DE = dyn_cast<DeclRefExpr>(*I);
+    if (!DE || !isa<VarDecl>(DE->getDecl())) {
+      Diag(ELoc, diag::err_omp_expected_var_name)
+        << (*I)->getSourceRange();
+      continue;
+    }
+    Decl *D = DE->getDecl();
+    VarDecl *VD = cast<VarDecl>(D);
+
+    QualType Type = VD->getType();
+    if (Type->isDependentType() || Type->isInstantiationDependentType()) {
+      // It will be analyzed later.
+      Vars.push_back(DE);
+      continue;
+    }
+
+    // OpenMP [2.9.1.1, Data-sharing Attribute Rules for Variables Referenced
+    // in a Construct]
+    //  Variables with the predetermined data-sharing attributes may not be
+    //  listed in data-sharing attributes clauses, except for the cases
+    //  listed below. For these exceptions only, listing a predetermined
+    //  variable in a data-sharing attribute clause is allowed and overrides
+    //  the variable's predetermined data-sharing attributes.
+    DSAStackTy::DSAVarData DVar = DSAStack->getTopDSA(VD);
+    if (DVar.CKind != OMPC_unknown && DVar.CKind != OMPC_shared && DVar.RefExpr) {
+      Diag(ELoc, diag::err_omp_wrong_dsa)
+         << getOpenMPClauseName(DVar.CKind)
+         << getOpenMPClauseName(OMPC_shared);
+      Diag(DVar.RefExpr->getExprLoc(), diag::note_omp_explicit_dsa)
+           << getOpenMPClauseName(DVar.CKind);
+      continue;
+    }
+
+    DSAStack->addDSA(VD, DE, OMPC_shared);
+    Vars.push_back(DE);
+  }
+
+  if (Vars.empty()) return 0;
+
+  return OMPSharedClause::Create(Context, StartLoc, LParenLoc, EndLoc, Vars);
+}
+
+#undef DSAStack
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index cd0ffdd8e96..947fc241993 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1312,6 +1312,14 @@ public:
                                               EndLoc);
   }
 
+  OMPClause *RebuildOMPSharedClause(ArrayRef<Expr *> VarList,
+                                    SourceLocation StartLoc,
+                                    SourceLocation LParenLoc,
+                                    SourceLocation EndLoc) {
+    return getSema().ActOnOpenMPSharedClause(VarList, StartLoc, LParenLoc,
+                                             EndLoc);
+  }
+
   /// \brief Rebuild the operand to an Objective-C \@synchronized statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
@@ -6254,33 +6262,44 @@ TreeTransform<Derived>::TransformSEHHandler(Stmt *Handler) {
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPParallelDirective(OMPParallelDirective *D) {
+  DeclarationNameInfo DirName;
+  getSema().StartOpenMPDSABlock(OMPD_parallel, DirName, 0);
+
   // Transform the clauses
-  SmallVector<OMPClause *, 5> TClauses;
+  llvm::SmallVector<OMPClause *, 16> TClauses;
   ArrayRef<OMPClause *> Clauses = D->clauses();
   TClauses.reserve(Clauses.size());
   for (ArrayRef<OMPClause *>::iterator I = Clauses.begin(), E = Clauses.end();
        I != E; ++I) {
     if (*I) {
       OMPClause *Clause = getDerived().TransformOMPClause(*I);
-      if (!Clause)
+      if (!Clause) {
+        getSema().EndOpenMPDSABlock(0);
         return StmtError();
+      }
       TClauses.push_back(Clause);
     }
     else {
       TClauses.push_back(0);
     }
   }
-  if (!D->getAssociatedStmt())
+  if (!D->getAssociatedStmt()) {
+    getSema().EndOpenMPDSABlock(0);
     return StmtError();
+  }
   StmtResult AssociatedStmt =
     getDerived().TransformStmt(D->getAssociatedStmt());
-  if (AssociatedStmt.isInvalid())
+  if (AssociatedStmt.isInvalid()) {
+    getSema().EndOpenMPDSABlock(0);
     return StmtError();
+  }
 
-  return getDerived().RebuildOMPParallelDirective(TClauses,
-                                                  AssociatedStmt.take(),
-                                                  D->getLocStart(),
-                                                  D->getLocEnd());
+  StmtResult Res = getDerived().RebuildOMPParallelDirective(TClauses,
+                                                            AssociatedStmt.take(),
+                                                            D->getLocStart(),
+                                                            D->getLocEnd());
+  getSema().EndOpenMPDSABlock(Res.get());
+  return Res;
 }
 
 template<typename Derived>
@@ -6296,7 +6315,7 @@ TreeTransform<Derived>::TransformOMPDefaultClause(OMPDefaultClause *C) {
 template<typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPPrivateClause(OMPPrivateClause *C) {
-  SmallVector<Expr *, 5> Vars;
+  llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (OMPVarList<OMPPrivateClause>::varlist_iterator I = C->varlist_begin(),
                                                       E = C->varlist_end();
@@ -6312,6 +6331,25 @@ TreeTransform<Derived>::TransformOMPPrivateClause(OMPPrivateClause *C) {
                                               C->getLocEnd());
 }
 
+template<typename Derived>
+OMPClause *
+TreeTransform<Derived>::TransformOMPSharedClause(OMPSharedClause *C) {
+  llvm::SmallVector<Expr *, 16> Vars;
+  Vars.reserve(C->varlist_size());
+  for (OMPVarList<OMPSharedClause>::varlist_iterator I = C->varlist_begin(),
+                                                     E = C->varlist_end();
+       I != E; ++I) {
+    ExprResult EVar = getDerived().TransformExpr(cast<Expr>(*I));
+    if (EVar.isInvalid())
+      return 0;
+    Vars.push_back(EVar.take());
+  }
+  return getDerived().RebuildOMPSharedClause(Vars,
+                                             C->getLocStart(),
+                                             C->getLParenLoc(),
+                                             C->getLocEnd());
+}
+
 //===----------------------------------------------------------------------===//
 // Expression transformation
 //===----------------------------------------------------------------------===//