[OpenMP] Parsing and sema support for the from clause

[sfantao]

Summary

The patch contains the parsing and sema support for the from clause.

Patch based on the original post by Kelvin Li.

[ABataev]

There must be separate patch for 'from' and separate patch for 'to'

[kkwli0]

Ok, thanks. I will split it into two patches.

[sfantao]

Implementation and tests only for the from clause. Similarly to the to clause, the implementation is based on the infrastructure contributed before for the map clause.

[ABataev]

Missed a test for printing and serialization/deserialization

test/OpenMP/nesting_of_regions.cpp

1832 ↗

(On Diff #58371)

Again, this test must be updated only for new directives, not clauses

[sfantao]

• Rebase and remove changes from the nesting tests.

[sfantao]

Hi Alexey,

Thanks for the review!

In D18488#438841, @ABataev wrote:

Missed a test for printing and serialization/deserialization

Maybe it is test/OpenMP/target_update_ast_print.cpp what you were looking for? Let me know if not.

Thanks again,
Samuel

test/OpenMP/nesting_of_regions.cpp

1832 ↗

(On Diff #58371)

Ok, I'm not touching this test in this patch anymore.

[ABataev]

LG

include/clang/AST/OpenMPClause.h

static bool classof(const OMPClause *T) {
     return T->getClauseKind() == OMPC_to;
   }
 
   child_range children() {
     return child_range(reinterpret_cast<Stmt **>(varlist_begin()),
                        reinterpret_cast<Stmt **>(varlist_end()));
   }
 };
+
+/// \brief This represents clause 'from' in the '#pragma omp ...'
+/// directives.
+///
+/// \code
+/// #pragma omp target update from(a,b)
+/// \endcode
+/// In this example directive '#pragma omp target update' has clause 'from'
+/// with the variables 'a' and 'b'.
+///
+class OMPFromClause final
+    : public OMPMappableExprListClause<OMPFromClause>,
+      private llvm::TrailingObjects<
+          OMPFromClause, Expr *, ValueDecl *, unsigned,
+          OMPClauseMappableExprCommon::MappableComponent> {
+  friend TrailingObjects;
+  friend OMPVarListClause;
+  friend OMPMappableExprListClause;
+  friend class OMPClauseReader;
+
+  /// Define the sizes of each trailing object array except the last one. This
+  /// is required for TrailingObjects to work properly.
+  size_t numTrailingObjects(OverloadToken<Expr *>) const {
+    return varlist_size();
+  }
+  size_t numTrailingObjects(OverloadToken<ValueDecl *>) const {
+    return getUniqueDeclarationsNum();
+  }
+  size_t numTrailingObjects(OverloadToken<unsigned>) const {
+    return getUniqueDeclarationsNum() + getTotalComponentListNum();
+  }
+
+  /// \brief Build clause with number of variables \a NumVars.
+  ///
+  /// \param StartLoc Starting location of the clause.
+  /// \param EndLoc Ending location of the clause.
+  /// \param NumVars Number of expressions listed in this clause.
+  /// \param NumUniqueDeclarations Number of unique base declarations in this
+  /// clause.
+  /// \param NumComponentLists Number of component lists in this clause.
+  /// \param NumComponents Total number of expression components in the clause.
+  ///
+  explicit OMPFromClause(SourceLocation StartLoc, SourceLocation LParenLoc,
+                         SourceLocation EndLoc, unsigned NumVars,
+                         unsigned NumUniqueDeclarations,
+                         unsigned NumComponentLists, unsigned NumComponents)
+      : OMPMappableExprListClause(OMPC_from, StartLoc, LParenLoc, EndLoc,
+                                  NumVars, NumUniqueDeclarations,
+                                  NumComponentLists, NumComponents) {}
+
+  /// \brief Build an empty clause.
+  ///
+  /// \param NumVars Number of expressions listed in this clause.
+  /// \param NumUniqueDeclarations Number of unique base declarations in this
+  /// clause.
+  /// \param NumComponentLists Number of component lists in this clause.
+  /// \param NumComponents Total number of expression components in the clause.
+  ///
+  explicit OMPFromClause(unsigned NumVars, unsigned NumUniqueDeclarations,
+                         unsigned NumComponentLists, unsigned NumComponents)
+      : OMPMappableExprListClause(
+            OMPC_from, SourceLocation(), SourceLocation(), SourceLocation(),
+            NumVars, NumUniqueDeclarations, NumComponentLists, NumComponents) {}
+
+public:
+  /// \brief Creates clause with a list of variables \a Vars.
+  ///
+  /// \param C AST context.
+  /// \brief StartLoc Starting location of the clause.
+  /// \brief EndLoc Ending location of the clause.
+  /// \param Vars The original expression used in the clause.
+  /// \param Declarations Declarations used in the clause.
+  /// \param ComponentLists Component lists used in the clause.
+  ///
+  static OMPFromClause *Create(const ASTContext &C, SourceLocation StartLoc,
+                               SourceLocation LParenLoc, SourceLocation EndLoc,
+                               ArrayRef<Expr *> Vars,
+                               ArrayRef<ValueDecl *> Declarations,
+                               MappableExprComponentListsRef ComponentLists);
+
+  /// \brief Creates an empty clause with the place for \a NumVars variables.
+  ///
+  /// \param C AST context.
+  /// \param NumVars Number of expressions listed in the clause.
+  /// \param NumUniqueDeclarations Number of unique base declarations in this
+  /// clause.
+  /// \param NumComponentLists Number of unique base declarations in this
+  /// clause.
+  /// \param NumComponents Total number of expression components in the clause.
+  ///
+  static OMPFromClause *CreateEmpty(const ASTContext &C, unsigned NumVars,
+                                    unsigned NumUniqueDeclarations,
+                                    unsigned NumComponentLists,
+                                    unsigned NumComponents);
+
+  static bool classof(const OMPClause *T) {
+    return T->getClauseKind() == OMPC_from;
+  }
+
+  child_range children() {
+    return child_range(reinterpret_cast<Stmt **>(varlist_begin()),
+                       reinterpret_cast<Stmt **>(varlist_end()));
+  }
+};
 } // end namespace clang
 
 #endif // LLVM_CLANG_AST_OPENMPCLAUSE_H

include/clang/AST/RecursiveASTVisitor.h

 }
 
 template <typename Derived>
 bool RecursiveASTVisitor<Derived>::VisitOMPToClause(OMPToClause *C) {
   TRY_TO(VisitOMPClauseList(C));
   return true;
 }
 
+template <typename Derived>
+bool RecursiveASTVisitor<Derived>::VisitOMPFromClause(OMPFromClause *C) {
+  TRY_TO(VisitOMPClauseList(C));
+  return true;
+}
+
 // FIXME: look at the following tricky-seeming exprs to see if we
 // need to recurse on anything.  These are ones that have methods
 // returning decls or qualtypes or nestednamespecifier -- though I'm
 // not sure if they own them -- or just seemed very complicated, or
 // had lots of sub-types to explore.
 //
 // VisitOverloadExpr and its children: recurse on template args? etc?
 

include/clang/Basic/OpenMPKinds.def

 OPENMP_CLAUSE(priority, OMPPriorityClause)
 OPENMP_CLAUSE(grainsize, OMPGrainsizeClause)
 OPENMP_CLAUSE(nogroup, OMPNogroupClause)
 OPENMP_CLAUSE(num_tasks, OMPNumTasksClause)
 OPENMP_CLAUSE(hint, OMPHintClause)
 OPENMP_CLAUSE(dist_schedule, OMPDistScheduleClause)
 OPENMP_CLAUSE(defaultmap, OMPDefaultmapClause)
 OPENMP_CLAUSE(to, OMPToClause)
+OPENMP_CLAUSE(from, OMPFromClause)
 
 // Clauses allowed for OpenMP directive 'parallel'.
 OPENMP_PARALLEL_CLAUSE(if)
 OPENMP_PARALLEL_CLAUSE(num_threads)
 OPENMP_PARALLEL_CLAUSE(default)
 OPENMP_PARALLEL_CLAUSE(proc_bind)
 OPENMP_PARALLEL_CLAUSE(private)
 OPENMP_PARALLEL_CLAUSE(firstprivate)

 OPENMP_TARGET_PARALLEL_FOR_CLAUSE(ordered)
 OPENMP_TARGET_PARALLEL_FOR_CLAUSE(linear)
 
 // Clauses allowed for OpenMP directive 'target update'.
 // TODO More clauses for 'target update' directive.
 OPENMP_TARGET_UPDATE_CLAUSE(if)
 OPENMP_TARGET_UPDATE_CLAUSE(device)
 OPENMP_TARGET_UPDATE_CLAUSE(to)
+OPENMP_TARGET_UPDATE_CLAUSE(from)
 
 // Clauses allowed for OpenMP directive 'teams'.
 // TODO More clauses for 'teams' directive.
 OPENMP_TEAMS_CLAUSE(default)
 OPENMP_TEAMS_CLAUSE(private)
 OPENMP_TEAMS_CLAUSE(firstprivate)
 OPENMP_TEAMS_CLAUSE(shared)
 OPENMP_TEAMS_CLAUSE(reduction)

include/clang/Sema/Sema.h

OMPClause *ActOnOpenMPDefaultmapClause(
       OpenMPDefaultmapClauseModifier M, OpenMPDefaultmapClauseKind Kind,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation MLoc,
       SourceLocation KindLoc, SourceLocation EndLoc);
   /// \brief Called on well-formed 'to' clause.
   OMPClause *ActOnOpenMPToClause(ArrayRef<Expr *> VarList,
                                  SourceLocation StartLoc,
                                  SourceLocation LParenLoc,
                                  SourceLocation EndLoc);
+  /// \brief Called on well-formed 'from' clause.
+  OMPClause *ActOnOpenMPFromClause(ArrayRef<Expr *> VarList,
+                                   SourceLocation StartLoc,
+                                   SourceLocation LParenLoc,
+                                   SourceLocation EndLoc);
 
   /// \brief The kind of conversion being performed.
   enum CheckedConversionKind {
     /// \brief An implicit conversion.
     CCK_ImplicitConversion,
     /// \brief A C-style cast.
     CCK_CStyleCast,
     /// \brief A functional-style cast.

lib/AST/OpenMPClause.cpp

const OMPClauseWithPreInit *OMPClauseWithPreInit::get(const OMPClause *C) {
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_defaultmap:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     break;
   }
 
   return nullptr;
 }
 
 OMPClauseWithPostUpdate *OMPClauseWithPostUpdate::get(OMPClause *C) {
   auto *Res = OMPClauseWithPostUpdate::get(const_cast<const OMPClause *>(C));
const OMPClauseWithPostUpdate *OMPClauseWithPostUpdate::get(const OMPClause *C) {
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_defaultmap:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     break;
   }
 
   return nullptr;
 }
 
 void OMPPrivateClause::setPrivateCopies(ArrayRef<Expr *> VL) {
   assert(VL.size() == varlist_size() &&
OMPToClause *OMPToClause::CreateEmpty(const ASTContext &C, unsigned NumVars,
   void *Mem = C.Allocate(
       totalSizeToAlloc<Expr *, ValueDecl *, unsigned,
                        OMPClauseMappableExprCommon::MappableComponent>(
           NumVars, NumUniqueDeclarations,
           NumUniqueDeclarations + NumComponentLists, NumComponents));
   return new (Mem) OMPToClause(NumVars, NumUniqueDeclarations,
                                NumComponentLists, NumComponents);
 }
+
+OMPFromClause *
+OMPFromClause::Create(const ASTContext &C, SourceLocation StartLoc,
+                      SourceLocation LParenLoc, SourceLocation EndLoc,
+                      ArrayRef<Expr *> Vars, ArrayRef<ValueDecl *> Declarations,
+                      MappableExprComponentListsRef ComponentLists) {
+  unsigned NumVars = Vars.size();
+  unsigned NumUniqueDeclarations =
+      getUniqueDeclarationsTotalNumber(Declarations);
+  unsigned NumComponentLists = ComponentLists.size();
+  unsigned NumComponents = getComponentsTotalNumber(ComponentLists);
+
+  // We need to allocate:
+  // NumVars x Expr* - we have an original list expression for each clause list
+  // entry.
+  // NumUniqueDeclarations x ValueDecl* - unique base declarations associated
+  // with each component list.
+  // (NumUniqueDeclarations + NumComponentLists) x unsigned - we specify the
+  // number of lists for each unique declaration and the size of each component
+  // list.
+  // NumComponents x MappableComponent - the total of all the components in all
+  // the lists.
+  void *Mem = C.Allocate(
+      totalSizeToAlloc<Expr *, ValueDecl *, unsigned,
+                       OMPClauseMappableExprCommon::MappableComponent>(
+          NumVars, NumUniqueDeclarations,
+          NumUniqueDeclarations + NumComponentLists, NumComponents));
+
+  OMPFromClause *Clause = new (Mem)
+      OMPFromClause(StartLoc, LParenLoc, EndLoc, NumVars, NumUniqueDeclarations,
+                    NumComponentLists, NumComponents);
+
+  Clause->setVarRefs(Vars);
+  Clause->setClauseInfo(Declarations, ComponentLists);
+  return Clause;
+}
+
+OMPFromClause *OMPFromClause::CreateEmpty(const ASTContext &C, unsigned NumVars,
+                                          unsigned NumUniqueDeclarations,
+                                          unsigned NumComponentLists,
+                                          unsigned NumComponents) {
+  void *Mem = C.Allocate(
+      totalSizeToAlloc<Expr *, ValueDecl *, unsigned,
+                       OMPClauseMappableExprCommon::MappableComponent>(
+          NumVars, NumUniqueDeclarations,
+          NumUniqueDeclarations + NumComponentLists, NumComponents));
+  return new (Mem) OMPFromClause(NumVars, NumUniqueDeclarations,
+                                 NumComponentLists, NumComponents);
+}

lib/AST/StmtPrinter.cpp

 void OMPClausePrinter::VisitOMPToClause(OMPToClause *Node) {
   if (!Node->varlist_empty()) {
     OS << "to";
     VisitOMPClauseList(Node, '(');
     OS << ")";
   }
 }
 
+void OMPClausePrinter::VisitOMPFromClause(OMPFromClause *Node) {
+  if (!Node->varlist_empty()) {
+    OS << "from";
+    VisitOMPClauseList(Node, '(');
+    OS << ")";
+  }
+}
+
 void OMPClausePrinter::VisitOMPDistScheduleClause(OMPDistScheduleClause *Node) {
   OS << "dist_schedule(" << getOpenMPSimpleClauseTypeName(
                            OMPC_dist_schedule, Node->getDistScheduleKind());
   if (auto *E = Node->getChunkSize()) {
     OS << ", ";
     E->printPretty(OS, nullptr, Policy);
   }
   OS << ")";

lib/AST/StmtProfile.cpp

void OMPClauseProfiler::VisitOMPNumTasksClause(const OMPNumTasksClause *C) {
   Profiler->VisitStmt(C->getNumTasks());
 }
 void OMPClauseProfiler::VisitOMPHintClause(const OMPHintClause *C) {
   Profiler->VisitStmt(C->getHint());
 }
 void OMPClauseProfiler::VisitOMPToClause(const OMPToClause *C) {
   VisitOMPClauseList(C);
 }
+void OMPClauseProfiler::VisitOMPFromClause(const OMPFromClause *C) {
+  VisitOMPClauseList(C);
+}
 }
 
 void
 StmtProfiler::VisitOMPExecutableDirective(const OMPExecutableDirective *S) {
   VisitStmt(S);
   OMPClauseProfiler P(this);
   ArrayRef<OMPClause *> Clauses = S->clauses();
   for (ArrayRef<OMPClause *>::iterator I = Clauses.begin(), E = Clauses.end();

lib/Basic/OpenMPKinds.cpp

#include "clang/Basic/OpenMPKinds.def"
   case OMPC_thread_limit:
   case OMPC_priority:
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
 }
 
 const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
                                                  unsigned Type) {
   switch (Kind) {
#include "clang/Basic/OpenMPKinds.def"
   case OMPC_thread_limit:
   case OMPC_priority:
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
 }
 
 bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
                                         OpenMPClauseKind CKind) {
   assert(DKind <= OMPD_unknown);

lib/CodeGen/CGStmtOpenMP.cpp

static void EmitOMPAtomicExpr(CodeGenFunction &CGF, OpenMPClauseKind Kind,
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_dist_schedule:
   case OMPC_defaultmap:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     llvm_unreachable("Clause is not allowed in 'omp atomic'.");
   }
 }
 
 void CodeGenFunction::EmitOMPAtomicDirective(const OMPAtomicDirective &S) {
   bool IsSeqCst = S.getSingleClause<OMPSeqCstClause>();
   OpenMPClauseKind Kind = OMPC_unknown;
   for (auto *C : S.clauses()) {

lib/Parse/ParseOpenMP.cpp

 ///       default-clause | private-clause | firstprivate-clause | shared-clause
 ///       | linear-clause | aligned-clause | collapse-clause |
 ///       lastprivate-clause | reduction-clause | proc_bind-clause |
 ///       schedule-clause | copyin-clause | copyprivate-clause | untied-clause |
 ///       mergeable-clause | flush-clause | read-clause | write-clause |
 ///       update-clause | capture-clause | seq_cst-clause | device-clause |
 ///       simdlen-clause | threads-clause | simd-clause | num_teams-clause |
 ///       thread_limit-clause | priority-clause | grainsize-clause |
-///       nogroup-clause | num_tasks-clause | hint-clause | to-clause
+///       nogroup-clause | num_tasks-clause | hint-clause | to-clause |
+///       from-clause
 ///
 OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
                                      OpenMPClauseKind CKind, bool FirstClause) {
   OMPClause *Clause = nullptr;
   bool ErrorFound = false;
   // Check if clause is allowed for the given directive.
   if (CKind != OMPC_unknown && !isAllowedClauseForDirective(DKind, CKind)) {
     Diag(Tok, diag::err_omp_unexpected_clause) << getOpenMPClauseName(CKind)
OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
   case OMPC_linear:
   case OMPC_aligned:
   case OMPC_copyin:
   case OMPC_copyprivate:
   case OMPC_flush:
   case OMPC_depend:
   case OMPC_map:
   case OMPC_to:
+  case OMPC_from:
     Clause = ParseOpenMPVarListClause(DKind, CKind);
     break;
   case OMPC_unknown:
     Diag(Tok, diag::warn_omp_extra_tokens_at_eol)
         << getOpenMPDirectiveName(DKind);
     SkipUntil(tok::annot_pragma_openmp_end, StopBeforeMatch);
     break;
   case OMPC_threadprivate:

 ///       'flush' '(' list ')'
 ///    depend-clause:
 ///       'depend' '(' in | out | inout : list | source ')'
 ///    map-clause:
 ///       'map' '(' [ [ always , ]
 ///          to | from | tofrom | alloc | release | delete ':' ] list ')';
 ///    to-clause:
 ///       'to' '(' list ')'
+///    from-clause:
+///       'from' '(' list ')'
 ///
 /// For 'linear' clause linear-list may have the following forms:
 ///  list
 ///  modifier(list)
 /// where modifier is 'val' (C) or 'ref', 'val' or 'uval'(C++).
 OMPClause *Parser::ParseOpenMPVarListClause(OpenMPDirectiveKind DKind,
                                             OpenMPClauseKind Kind) {
   SourceLocation Loc = Tok.getLocation();

lib/Sema/SemaOpenMP.cpp

Sema::ActOnOpenMPTargetExitDataDirective(ArrayRef<OMPClause *> Clauses,
   return OMPTargetExitDataDirective::Create(Context, StartLoc, EndLoc, Clauses);
 }
 
 StmtResult Sema::ActOnOpenMPTargetUpdateDirective(ArrayRef<OMPClause *> Clauses,
                                                   SourceLocation StartLoc,
                                                   SourceLocation EndLoc) {
   bool seenMotionClause = false;
   for (auto *C : Clauses) {
-    if (C->getClauseKind() == OMPC_to)
+    if (C->getClauseKind() == OMPC_to || C->getClauseKind() == OMPC_from)
       seenMotionClause = true;
   }
   if (!seenMotionClause) {
     Diag(StartLoc, diag::err_omp_at_least_one_motion_clause_required);
     return StmtError();
   }
   return OMPTargetUpdateDirective::Create(Context, StartLoc, EndLoc, Clauses);
 }
OMPClause *Sema::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind, Expr *Expr,
   case OMPC_simd:
   case OMPC_map:
   case OMPC_nogroup:
   case OMPC_dist_schedule:
   case OMPC_defaultmap:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
 }
 
 OMPClause *Sema::ActOnOpenMPIfClause(OpenMPDirectiveKind NameModifier,
                                      Expr *Condition, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
OMPClause *Sema::ActOnOpenMPSimpleClause(
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_dist_schedule:
   case OMPC_defaultmap:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
 }
 
 static std::string
 getListOfPossibleValues(OpenMPClauseKind K, unsigned First, unsigned Last,
                         ArrayRef<unsigned> Exclude = llvm::None) {
OMPClause *Sema::ActOnOpenMPSingleExprWithArgClause(
   case OMPC_priority:
   case OMPC_grainsize:
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
 }
 
 static bool checkScheduleModifiers(Sema &S, OpenMPScheduleClauseModifier M1,
                                    OpenMPScheduleClauseModifier M2,
                                    SourceLocation M1Loc, SourceLocation M2Loc) {
OMPClause *Sema::ActOnOpenMPClause(OpenMPClauseKind Kind,
   case OMPC_grainsize:
   case OMPC_num_tasks:
   case OMPC_hint:
   case OMPC_dist_schedule:
   case OMPC_defaultmap:
   case OMPC_unknown:
   case OMPC_uniform:
   case OMPC_to:
+  case OMPC_from:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
 }
 
 OMPClause *Sema::ActOnOpenMPNowaitClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
   DSAStack->setNowaitRegion();
OMPClause *Sema::ActOnOpenMPVarListClause(
   case OMPC_map:
     Res = ActOnOpenMPMapClause(MapTypeModifier, MapType, IsMapTypeImplicit,
                                DepLinMapLoc, ColonLoc, VarList, StartLoc,
                                LParenLoc, EndLoc);
     break;
   case OMPC_to:
     Res = ActOnOpenMPToClause(VarList, StartLoc, LParenLoc, EndLoc);
     break;
+  case OMPC_from:
+    Res = ActOnOpenMPFromClause(VarList, StartLoc, LParenLoc, EndLoc);
+    break;
   case OMPC_if:
   case OMPC_final:
   case OMPC_num_threads:
   case OMPC_safelen:
   case OMPC_simdlen:
   case OMPC_collapse:
   case OMPC_default:
   case OMPC_proc_bind:
bool FoundError = DSAS->checkMappableExprComponentListsForDecl(
         //
         // If the expressions are exactly the same or one is a subset of the
         // other, it means they are sharing storage.
         if (CI == CE && SI == SE) {
           if (CurrentRegionOnly) {
             if (CKind == OMPC_map)
               SemaRef.Diag(ELoc, diag::err_omp_map_shared_storage) << ERange;
             else {
-              assert(CKind == OMPC_to);
+              assert(CKind == OMPC_to || CKind == OMPC_from);
               SemaRef.Diag(ELoc, diag::err_omp_once_referenced_in_target_update)
                   << ERange;
             }
             SemaRef.Diag(RE->getExprLoc(), diag::note_used_here)
                 << RE->getSourceRange();
             return true;
           } else {
             // If we find the same expression in the enclosing data environment,
bool FoundError = DSAS->checkMappableExprComponentListsForDecl(
         //  List items of map clauses in the same construct must not share
         //  original storage.
         //
         // An expression is a subset of the other.
         if (CurrentRegionOnly && (CI == CE || SI == SE)) {
           if (CKind == OMPC_map)
             SemaRef.Diag(ELoc, diag::err_omp_map_shared_storage) << ERange;
           else {
-            assert(CKind == OMPC_to);
+            assert(CKind == OMPC_to || CKind == OMPC_from);
             SemaRef.Diag(ELoc, diag::err_omp_once_referenced_in_target_update)
                 << ERange;
           }
           SemaRef.Diag(RE->getExprLoc(), diag::note_used_here)
               << RE->getSourceRange();
           return true;
         }
 

 // \a ClauseComponents, and \a ClauseBaseDeclarations. \a MapType and
 // \a IsMapTypeImplicit are expected to be valid if the clause kind is 'map'.
 static void
 checkMappableExpressionList(Sema &SemaRef, DSAStackTy *DSAS,
                             OpenMPClauseKind CKind, MappableVarListInfo &MVLI,
                             SourceLocation StartLoc,
                             OpenMPMapClauseKind MapType = OMPC_MAP_unknown,
                             bool IsMapTypeImplicit = false) {
-  // We only expect mappable expressions in 'to' and 'map' clauses.
-  assert((CKind == OMPC_map || CKind == OMPC_to) &&
+  // We only expect mappable expressions in 'to', 'from', and 'map' clauses.
+  assert((CKind == OMPC_map || CKind == OMPC_to || CKind == OMPC_from) &&
          "Unexpected clause kind with mappable expressions!");
 
   // Keep track of the mappable components and base declarations in this clause.
   // Each entry in the list is going to have a list of components associated. We
   // record each set of the components so that we can build the clause later on.
   // In the end we should have the same amount of declarations and component
   // lists.
 
   for (auto &RE : MVLI.VarList) {
-    assert(RE && "Null expr in omp to/map clause");
+    assert(RE && "Null expr in omp to/from/map clause");
     SourceLocation ELoc = RE->getExprLoc();
 
     auto *VE = RE->IgnoreParenLValueCasts();
 
     if (VE->isValueDependent() || VE->isTypeDependent() ||
         VE->isInstantiationDependent() ||
         VE->containsUnexpandedParameterPack()) {
       // We can only analyze this information once the missing information is
OMPClause *Sema::ActOnOpenMPToClause(ArrayRef<Expr *> VarList,
   checkMappableExpressionList(*this, DSAStack, OMPC_to, MVLI, StartLoc);
   if (MVLI.ProcessedVarList.empty())
     return nullptr;
 
   return OMPToClause::Create(Context, StartLoc, LParenLoc, EndLoc,
                              MVLI.ProcessedVarList, MVLI.VarBaseDeclarations,
                              MVLI.VarComponents);
 }
+
+OMPClause *Sema::ActOnOpenMPFromClause(ArrayRef<Expr *> VarList,
+                                       SourceLocation StartLoc,
+                                       SourceLocation LParenLoc,
+                                       SourceLocation EndLoc) {
+  MappableVarListInfo MVLI(VarList);
+  checkMappableExpressionList(*this, DSAStack, OMPC_from, MVLI, StartLoc);
+  if (MVLI.ProcessedVarList.empty())
+    return nullptr;
+
+  return OMPFromClause::Create(Context, StartLoc, LParenLoc, EndLoc,
+                               MVLI.ProcessedVarList, MVLI.VarBaseDeclarations,
+                               MVLI.VarComponents);
+}

lib/Sema/TreeTransform.h

   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPToClause(ArrayRef<Expr *> VarList,
                                 SourceLocation StartLoc,
                                 SourceLocation LParenLoc,
                                 SourceLocation EndLoc) {
     return getSema().ActOnOpenMPToClause(VarList, StartLoc, LParenLoc, EndLoc);
   }
 
+  /// \brief Build a new OpenMP 'from' clause.
+  ///
+  /// By default, performs semantic analysis to build the new statement.
+  /// Subclasses may override this routine to provide different behavior.
+  OMPClause *RebuildOMPFromClause(ArrayRef<Expr *> VarList,
+                                  SourceLocation StartLoc,
+                                  SourceLocation LParenLoc,
+                                  SourceLocation EndLoc) {
+    return getSema().ActOnOpenMPFromClause(VarList, StartLoc, LParenLoc,
+                                           EndLoc);
+  }
+
   /// \brief Rebuild the operand to an Objective-C \@synchronized statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCAtSynchronizedOperand(SourceLocation atLoc,
                                               Expr *object) {
     return getSema().ActOnObjCAtSynchronizedOperand(atLoc, object);
   }
for (auto *VE : C->varlists()) {
     if (EVar.isInvalid())
       return 0;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPToClause(Vars, C->getLocStart(),
                                          C->getLParenLoc(), C->getLocEnd());
 }
 
+template <typename Derived>
+OMPClause *TreeTransform<Derived>::TransformOMPFromClause(OMPFromClause *C) {
+  llvm::SmallVector<Expr *, 16> Vars;
+  Vars.reserve(C->varlist_size());
+  for (auto *VE : C->varlists()) {
+    ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
+    if (EVar.isInvalid())
+      return 0;
+    Vars.push_back(EVar.get());
+  }
+  return getDerived().RebuildOMPFromClause(Vars, C->getLocStart(),
+                                           C->getLParenLoc(), C->getLocEnd());
+}
+
 //===----------------------------------------------------------------------===//
 // Expression transformation
 //===----------------------------------------------------------------------===//
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExpr *E) {
   if (!E->isTypeDependent())
     return E;

lib/Serialization/ASTReaderStmt.cpp

case OMPC_to: {
     unsigned NumVars = Record[Idx++];
     unsigned NumDeclarations = Record[Idx++];
     unsigned NumLists = Record[Idx++];
     unsigned NumComponents = Record[Idx++];
     C = OMPToClause::CreateEmpty(Context, NumVars, NumDeclarations, NumLists,
                                  NumComponents);
     break;
   }
+  case OMPC_from: {
+    unsigned NumVars = Record[Idx++];
+    unsigned NumDeclarations = Record[Idx++];
+    unsigned NumLists = Record[Idx++];
+    unsigned NumComponents = Record[Idx++];
+    C = OMPFromClause::CreateEmpty(Context, NumVars, NumDeclarations, NumLists,
+                                   NumComponents);
+    break;
+  }
   }
   Visit(C);
   C->setLocStart(Reader->ReadSourceLocation(Record, Idx));
   C->setLocEnd(Reader->ReadSourceLocation(Record, Idx));
 
   return C;
 }
 
for (unsigned i = 0; i < TotalComponents; ++i) {
     ValueDecl *AssociatedDecl =
         Reader->Reader.ReadDeclAs<ValueDecl>(Reader->F, Record, Idx);
     Components.push_back(OMPClauseMappableExprCommon::MappableComponent(
         AssociatedExpr, AssociatedDecl));
   }
   C->setComponents(Components, ListSizes);
 }
 
+void OMPClauseReader::VisitOMPFromClause(OMPFromClause *C) {
+  C->setLParenLoc(Reader->ReadSourceLocation(Record, Idx));
+  auto NumVars = C->varlist_size();
+  auto UniqueDecls = C->getUniqueDeclarationsNum();
+  auto TotalLists = C->getTotalComponentListNum();
+  auto TotalComponents = C->getTotalComponentsNum();
+
+  SmallVector<Expr *, 16> Vars;
+  Vars.reserve(NumVars);
+  for (unsigned i = 0; i != NumVars; ++i)
+    Vars.push_back(Reader->Reader.ReadSubExpr());
+  C->setVarRefs(Vars);
+
+  SmallVector<ValueDecl *, 16> Decls;
+  Decls.reserve(UniqueDecls);
+  for (unsigned i = 0; i < UniqueDecls; ++i)
+    Decls.push_back(
+        Reader->Reader.ReadDeclAs<ValueDecl>(Reader->F, Record, Idx));
+  C->setUniqueDecls(Decls);
+
+  SmallVector<unsigned, 16> ListsPerDecl;
+  ListsPerDecl.reserve(UniqueDecls);
+  for (unsigned i = 0; i < UniqueDecls; ++i)
+    ListsPerDecl.push_back(Record[Idx++]);
+  C->setDeclNumLists(ListsPerDecl);
+
+  SmallVector<unsigned, 32> ListSizes;
+  ListSizes.reserve(TotalLists);
+  for (unsigned i = 0; i < TotalLists; ++i)
+    ListSizes.push_back(Record[Idx++]);
+  C->setComponentListSizes(ListSizes);
+
+  SmallVector<OMPClauseMappableExprCommon::MappableComponent, 32> Components;
+  Components.reserve(TotalComponents);
+  for (unsigned i = 0; i < TotalComponents; ++i) {
+    Expr *AssociatedExpr = Reader->Reader.ReadSubExpr();
+    ValueDecl *AssociatedDecl =
+        Reader->Reader.ReadDeclAs<ValueDecl>(Reader->F, Record, Idx);
+    Components.push_back(OMPClauseMappableExprCommon::MappableComponent(
+        AssociatedExpr, AssociatedDecl));
+  }
+  C->setComponents(Components, ListSizes);
+}
+
 //===----------------------------------------------------------------------===//
 // OpenMP Directives.
 //===----------------------------------------------------------------------===//
 void ASTStmtReader::VisitOMPExecutableDirective(OMPExecutableDirective *E) {
   E->setLocStart(ReadSourceLocation(Record, Idx));
   E->setLocEnd(ReadSourceLocation(Record, Idx));
   OMPClauseReader ClauseReader(this, Reader.getContext(), Record, Idx);
   SmallVector<OMPClause *, 5> Clauses;

lib/Serialization/ASTWriterStmt.cpp

void OMPClauseWriter::VisitOMPToClause(OMPToClause *C) {
   for (auto N : C->all_lists_sizes())
     Record.push_back(N);
   for (auto &M : C->all_components()) {
     Record.AddStmt(M.getAssociatedExpression());
     Record.AddDeclRef(M.getAssociatedDeclaration());
   }
 }
 
+void OMPClauseWriter::VisitOMPFromClause(OMPFromClause *C) {
+  Record.push_back(C->varlist_size());
+  Record.push_back(C->getUniqueDeclarationsNum());
+  Record.push_back(C->getTotalComponentListNum());
+  Record.push_back(C->getTotalComponentsNum());
+  Record.AddSourceLocation(C->getLParenLoc());
+  for (auto *E : C->varlists())
+    Record.AddStmt(E);
+  for (auto *D : C->all_decls())
+    Record.AddDeclRef(D);
+  for (auto N : C->all_num_lists())
+    Record.push_back(N);
+  for (auto N : C->all_lists_sizes())
+    Record.push_back(N);
+  for (auto &M : C->all_components()) {
+    Record.AddStmt(M.getAssociatedExpression());
+    Record.AddDeclRef(M.getAssociatedDeclaration());
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // OpenMP Directives.
 //===----------------------------------------------------------------------===//
 void ASTStmtWriter::VisitOMPExecutableDirective(OMPExecutableDirective *E) {
   Record.AddSourceLocation(E->getLocStart());
   Record.AddSourceLocation(E->getLocEnd());
   OMPClauseWriter ClauseWriter(Record);
   for (unsigned i = 0; i < E->getNumClauses(); ++i) {

test/OpenMP/target_update_ast_print.cpp

 // RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
 // RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
 // expected-no-diagnostics
 
 #ifndef HEADER
 #define HEADER
 
 void foo() {}
 
 template <class T, class U>
 T foo(T targ, U uarg) {
   static T a;
   U b;
   int l;
 #pragma omp target update to(a) if(l>5) device(l)
+
+#pragma omp target update from(b) if(l<5) device(l-1)
   return a + targ + (T)b;
 }
 // CHECK:      static int a;
 // CHECK-NEXT: float b;
 // CHECK-NEXT: int l;
 // CHECK-NEXT: #pragma omp target update to(a) if(l > 5) device(l)
+// CHECK-NEXT: #pragma omp target update from(b) if(l < 5) device(l - 1)
 // CHECK:      static char a;
 // CHECK-NEXT: float b;
 // CHECK-NEXT: int l;
 // CHECK-NEXT: #pragma omp target update to(a) if(l > 5) device(l)
+// CHECK-NEXT: #pragma omp target update from(b) if(l < 5) device(l - 1)
 // CHECK:      static T a;
 // CHECK-NEXT: U b;
 // CHECK-NEXT: int l;
 // CHECK-NEXT: #pragma omp target update to(a) if(l > 5) device(l)
+// CHECK-NEXT: #pragma omp target update from(b) if(l < 5) device(l - 1)
 
 int main(int argc, char **argv) {
   static int a;
   int n;
   float f;
 
 // CHECK:      static int a;
 // CHECK-NEXT: int n;
 // CHECK-NEXT: float f;
 #pragma omp target update to(a) if(f>0.0) device(n)
   // CHECK-NEXT: #pragma omp target update to(a) if(f > 0.) device(n)
+#pragma omp target update from(f) if(f<0.0) device(n+1)
+  // CHECK-NEXT: #pragma omp target update from(f) if(f < 0.) device(n + 1)
   return foo(argc, f) + foo(argv[0][0], f) + a;
 }
 
 #endif

test/OpenMP/target_update_device_messages.cpp

 template <class T, class S>
 int tmain(T argc, S **argv) {
   int i;
 #pragma omp target update to(i) device // expected-error {{expected '(' after 'device'}}
 #pragma omp target update to(i) device ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(i) device () // expected-error {{expected expression}}
 #pragma omp target update to(i) device (argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(i) device (argc)) // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
-#pragma omp target update device (argc > 0 ? argv[1] : argv[2]) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update device (argc + argc)  // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update device (argc), device (argc+1) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'device' clause}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update device (S1) // expected-error {{'S1' does not refer to a value}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update device (3.14) // expected-error {{expression must have integral or unscoped enumeration type, not 'double'}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update device (-2) // expected-error {{argument to 'device' clause must be a non-negative integer value}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(i) device (argc > 0 ? argv[1] : argv[2]) // expected-error {{expression must have integral or unscoped enumeration type, not 'char *'}}
+#pragma omp target update from(i) device (argc + argc)
+#pragma omp target update from(i) device (argc), device (argc+1) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'device' clause}}
+#pragma omp target update from(i) device (S1) // expected-error {{'S1' does not refer to a value}}
+#pragma omp target update from(i) device (3.14) // expected-error 2 {{expression must have integral or unscoped enumeration type, not 'double'}}
+#pragma omp target update from(i) device (-2) // expected-error {{argument to 'device' clause must be a non-negative integer value}}
 }
 
 int main(int argc, char **argv) {
   int j;
 #pragma omp target update to(j) device // expected-error {{expected '(' after 'device'}}
-#pragma omp target update device ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(j) device ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(j) device () // expected-error {{expected expression}}
-#pragma omp target update device (argc // expected-error {{expected ')'}} expected-note {{to match this '('}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(j) device (argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(j) device (argc)) // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
-#pragma omp target update device (argc > 0 ? argv[1] : argv[2]) // expected-error {{expression must have integral or unscoped enumeration type, not 'char *'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(j) device (argc > 0 ? argv[1] : argv[2]) // expected-error {{expression must have integral or unscoped enumeration type, not 'char *'}}
 #pragma omp target update to(j) device (argc + argc)
-#pragma omp target update device (argc), device (argc+1) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'device' clause}}  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(j) device (argc), device (argc+1) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'device' clause}}
 #pragma omp target update to(j) device (S1) // expected-error {{'S1' does not refer to a value}}
-#pragma omp target update device (-2) // expected-error {{argument to 'device' clause must be a non-negative integer value}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(j) device (-2) // expected-error {{argument to 'device' clause must be a non-negative integer value}}
 #pragma omp target update to(j) device (3.14) // expected-error {{expression must have integral or unscoped enumeration type, not 'double'}}
 
-  return tmain(argc, argv);
+  return tmain(argc, argv); // expected-note {{in instantiation of function template specialization 'tmain<int, char>' requested here}}
 }

test/OpenMP/target_update_from_messages.cpp

+// RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
+
+void foo() {
+}
+
+bool foobool(int argc) {
+  return argc;
+}
+
+struct S1; // expected-note 2 {{declared here}}
+extern S1 a;
+class S2 {
+  mutable int a;
+public:
+  S2():a(0) { }
+  S2(S2 &s2):a(s2.a) { }
+  static float S2s; // expected-note 4 {{mappable type cannot contain static members}}
+  static const float S2sc; // expected-note 4 {{mappable type cannot contain static members}}
+};
+const float S2::S2sc = 0;
+const S2 b;
+const S2 ba[5];
+class S3 {
+  int a;
+public:
+  S3():a(0) { }
+  S3(S3 &s3):a(s3.a) { }
+};
+const S3 c;
+const S3 ca[5];
+extern const int f;
+class S4 {
+  int a;
+  S4();
+  S4(const S4 &s4);
+public:
+  S4(int v):a(v) { }
+};
+class S5 {
+  int a;
+  S5():a(0) {}
+  S5(const S5 &s5):a(s5.a) { }
+public:
+  S5(int v):a(v) { }
+};
+struct S6 {
+  int ii;
+  int aa[30];
+  float xx;
+  double *pp;
+};
+struct S7 {
+  int i;
+  int a[50];
+  float x;
+  S6 s6[5];
+  double *p;
+  unsigned bfa : 4;
+};
+
+S3 h;
+#pragma omp threadprivate(h) // expected-note 2 {{defined as threadprivate or thread local}}
+
+typedef int to;
+
+template <typename T, int I> // expected-note {{declared here}}
+T tmain(T argc) {
+  const T d = 5;
+  const T da[5] = { 0 };
+  S4 e(4);
+  S5 g(5);
+  T i, t[20];
+  T &j = i;
+  T *k = &j;
+  T x;
+  T y;
+  T from;
+  const T (&l)[5] = da;
+  T *m;
+  S7 s7;
+
+#pragma omp target update from // expected-error {{expected '(' after 'from'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from( // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected expression}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from() // expected-error {{expected expression}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update() // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(alloc) // expected-error {{use of undeclared identifier 'alloc'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(x)
+#pragma omp target update from(t[:I])
+#pragma omp target update from(T) // expected-error {{'T' does not refer to a value}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(I) // expected-error 2 {{expected expression containing only member accesses and/or array sections based on named variables}}
+#pragma omp target update from(S2::S2s)
+#pragma omp target update from(S2::S2sc)
+#pragma omp target update from(from)
+#pragma omp target update from(y x) // expected-error {{expected ',' or ')' in 'from' clause}}
+#pragma omp target update from(argc > 0 ? x : y) // expected-error 2 {{expected expression containing only member accesses and/or array sections based on named variables}} 
+#pragma omp target update from(S1) // expected-error {{'S1' does not refer to a value}}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(a, b, c, d, f) // expected-error {{incomplete type 'S1' where a complete type is required}} expected-error 2 {{type 'S2' is not mappable to target}}
+#pragma omp target update from(ba) // expected-error 2 {{type 'S2' is not mappable to target}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(h) // expected-error {{threadprivate variables are not allowed in 'from' clause}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(k), to(k) // expected-error 2 {{variable can appear only once in OpenMP 'target update' construct}} expected-note 2 {{used here}}
+#pragma omp target update from(t), from(t[:5]) // expected-error 2 {{variable can appear only once in OpenMP 'target update' construct}} expected-note 2 {{used here}}
+#pragma omp target update from(da)
+#pragma omp target update from(da[:4])
+
+#pragma omp target update from(x, a[:2]) // expected-error {{subscripted value is not an array or pointer}}
+#pragma omp target update from(x, c[:]) // expected-error {{subscripted value is not an array or pointer}}
+#pragma omp target update from(x, (m+1)[2]) // expected-error 2 {{expected expression containing only member accesses and/or array sections based on named variables}}
+#pragma omp target update from(s7.i, s7.a[:3])
+#pragma omp target update from(s7.s6[1].aa[0:5])
+#pragma omp target update from(x, s7.s6[:5].aa[6]) // expected-error {{OpenMP array section is not allowed here}}
+#pragma omp target update from(x, s7.s6[:5].aa[:6]) // expected-error {{OpenMP array section is not allowed here}}
+#pragma omp target update from(s7.p[:10])
+#pragma omp target update from(x, s7.bfa) // expected-error {{bit fields cannot be used to specify storage in a 'from' clause}}
+#pragma omp target update from(x, s7.p[:]) // expected-error {{section length is unspecified and cannot be inferred because subscripted value is not an array}}
+#pragma omp target data map(to: s7.i)
+  {
+#pragma omp target update from(s7.x)
+  }
+
+  return 0;
+}
+
+int main(int argc, char **argv) {
+  const int d = 5;
+  const int da[5] = { 0 };
+  S4 e(4);
+  S5 g(5);
+  int i, t[20];
+  int &j = i;
+  int *k = &j;
+  int x;
+  int y;
+  int from;
+  const int (&l)[5] = da;
+  int *m;
+  S7 s7;
+
+#pragma omp target update from // expected-error {{expected '(' after 'from'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from( // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected expression}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from() // expected-error {{expected expression}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update() // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(alloc) // expected-error {{use of undeclared identifier 'alloc'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(x)
+#pragma omp target update from(t[:i])
+#pragma omp target update from(S2::S2s)
+#pragma omp target update from(S2::S2sc)
+#pragma omp target update from(from)
+#pragma omp target update from(y x) // expected-error {{expected ',' or ')' in 'from' clause}}
+#pragma omp target update from(argc > 0 ? x : y) // expected-error {{expected expression containing only member accesses and/or array sections based on named variables}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(S1) // expected-error {{'S1' does not refer to a value}}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(a, b, c, d, f) // expected-error {{incomplete type 'S1' where a complete type is required}} expected-error 2 {{type 'S2' is not mappable to target}}
+#pragma omp target update from(ba) // expected-error 2 {{type 'S2' is not mappable to target}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(h) // expected-error {{threadprivate variables are not allowed in 'from' clause}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(k), to(k) // expected-error {{variable can appear only once in OpenMP 'target update' construct}} expected-note {{used here}}
+#pragma omp target update from(t), from(t[:5]) // expected-error {{variable can appear only once in OpenMP 'target update' construct}} expected-note {{used here}}
+#pragma omp target update from(da)
+#pragma omp target update from(da[:4])
+
+#pragma omp target update from(x, a[:2]) // expected-error {{subscripted value is not an array or pointer}}
+#pragma omp target update from(x, c[:]) // expected-error {{subscripted value is not an array or pointer}}
+#pragma omp target update from(x, (m+1)[2]) // expected-error {{expected expression containing only member accesses and/or array sections based on named variables}}
+#pragma omp target update from(s7.i, s7.a[:3])
+#pragma omp target update from(s7.s6[1].aa[0:5])
+#pragma omp target update from(x, s7.s6[:5].aa[6]) // expected-error {{OpenMP array section is not allowed here}}
+#pragma omp target update from(x, s7.s6[:5].aa[:6]) // expected-error {{OpenMP array section is not allowed here}}
+#pragma omp target update from(s7.p[:10])
+#pragma omp target update from(x, s7.bfa) // expected-error {{bit fields cannot be used to specify storage in a 'from' clause}}
+#pragma omp target update from(x, s7.p[:]) // expected-error {{section length is unspecified and cannot be inferred because subscripted value is not an array}}
+#pragma omp target data map(to: s7.i)
+  {
+#pragma omp target update from(s7.x)
+  }
+
+  return tmain<int, 3>(argc)+tmain<to, 4>(argc); // expected-note {{in instantiation of function template specialization 'tmain<int, 3>' requested here}} expected-note {{in instantiation of function template specialization 'tmain<int, 4>' requested here}}
+}
+

test/OpenMP/target_update_if_messages.cpp

 // RUN: %clang_cc1 -verify -fopenmp -ferror-limit 100 %s
 
 void foo() {
 }
 
 bool foobool(int argc) {
   return argc;
 }
 
 struct S1; // expected-note {{declared here}}
 
 template <class T, class S> // expected-note {{declared here}}
 int tmain(T argc, S **argv) {
   int n;
 #pragma omp target update to(n) if // expected-error {{expected '(' after 'if'}}
-#pragma omp target update if ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(n) if () // expected-error {{expected expression}}
-#pragma omp target update if (argc // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if (argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(n) if (argc)) // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
-#pragma omp target update if (argc > 0 ? argv[1] : argv[2]) //  expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if (argc > 0 ? argv[1] : argv[2])
 #pragma omp target update to(n) if (foobool(argc)), if (true) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'if' clause}}
-#pragma omp target update if (S) // expected-error {{'S' does not refer to a value}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if (S) // expected-error {{'S' does not refer to a value}}
 #pragma omp target update to(n) if (argv[1]=2) // expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if (argc argc) // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if (argc argc) // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(n) if(argc)
-#pragma omp target update if(target update // expected-warning {{missing ':' after directive name modifier - ignoring}} expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if(target update // expected-warning {{missing ':' after directive name modifier - ignoring}} expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(n) if(target update : // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if(target update : argc // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if(target update : argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(n) if(target update : argc)
-#pragma omp target update if(target update : argc) if (for:argc) // expected-error {{directive name modifier 'for' is not allowed for '#pragma omp target update'}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if(target update : argc) if (for:argc) // expected-error {{directive name modifier 'for' is not allowed for '#pragma omp target update'}}
 #pragma omp target update to(n) if(target update : argc) if (target update:argc) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'if' clause with 'target update' name modifier}}
-#pragma omp target update if(target update : argc) if (argc) // expected-error {{no more 'if' clause is allowed}} expected-note {{previous clause with directive name modifier specified here}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(n) if(target update : argc) if (argc) // expected-error {{no more 'if' clause is allowed}} expected-note {{previous clause with directive name modifier specified here}}
   return 0;
 }
 
 int main(int argc, char **argv) {
   int m;
 #pragma omp target update to(m) if // expected-error {{expected '(' after 'if'}}
-#pragma omp target update if ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if ( // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(m) if () // expected-error {{expected expression}}
-#pragma omp target update if (argc // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if (argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(m) if (argc)) // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
-#pragma omp target update if (argc > 0 ? argv[1] : argv[2]) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if (argc > 0 ? argv[1] : argv[2])
 #pragma omp target update to(m) if (foobool(argc)), if (true) // expected-error {{directive '#pragma omp target update' cannot contain more than one 'if' clause}}
-#pragma omp target update if (S1) // expected-error {{'S1' does not refer to a value}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if (S1) // expected-error {{'S1' does not refer to a value}}
 #pragma omp target update to(m) if (argv[1]=2) // expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if (argc argc) // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if (argc argc) // expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(m) if (1 0) // expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if(if(tmain(argc, argv) // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if(if(tmain(argc, argv) // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(m) if(target update // expected-warning {{missing ':' after directive name modifier - ignoring}} expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if(target update : // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if(target update : // expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp target update to(m) if(target update : argc // expected-error {{expected ')'}} expected-note {{to match this '('}}
-#pragma omp target update if(target update : argc) // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if(target update : argc)
 #pragma omp target update to(m) if(target update : argc) if (for:argc) // expected-error {{directive name modifier 'for' is not allowed for '#pragma omp target update'}}
-#pragma omp target update if(target update : argc) if (target update:argc)  // expected-error {{directive '#pragma omp target update' cannot contain more than one 'if' clause with 'target update' name modifier}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
+#pragma omp target update from(m) if(target update : argc) if (target update:argc)  // expected-error {{directive '#pragma omp target update' cannot contain more than one 'if' clause with 'target update' name modifier}}
 #pragma omp target update to(m) if(target update : argc) if (argc) // expected-error {{no more 'if' clause is allowed}} expected-note {{previous clause with directive name modifier specified here}}
   return tmain(argc, argv);
 }

test/OpenMP/target_update_messages.cpp

int main(int argc, char **argv) {
   int m;
   #pragma omp target update // expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
   #pragma omp target update to(m) { // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
   #pragma omp target update to(m) ( // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
   #pragma omp target update to(m) [ // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
   #pragma omp target update to(m) ] // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
   #pragma omp target update to(m) ) // expected-warning {{extra tokens at the end of '#pragma omp target update' are ignored}}
 
-  #pragma omp target update to(m) // OK
+  #pragma omp target update from(m) // OK
   {
     foo();
   }
   return tmain(argc, argv);
 }

test/OpenMP/target_update_to_messages.cpp

 #pragma omp target update to(S2::S2sc)
 #pragma omp target update to(to)
 #pragma omp target update to(y x) // expected-error {{expected ',' or ')' in 'to' clause}}
 #pragma omp target update to(argc > 0 ? x : y) // expected-error 2 {{expected expression containing only member accesses and/or array sections based on named variables}} 
 #pragma omp target update to(S1) // expected-error {{'S1' does not refer to a value}}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(a, b, c, d, f) // expected-error {{incomplete type 'S1' where a complete type is required}} expected-error 2 {{type 'S2' is not mappable to target}}
 #pragma omp target update to(ba) // expected-error 2 {{type 'S2' is not mappable to target}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(h) // expected-error {{threadprivate variables are not allowed in 'to' clause}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(k), to(k) // expected-error 2 {{variable can appear only once in OpenMP 'target update' construct}} expected-note 2 {{used here}}
+#pragma omp target update to(k), from(k) // expected-error 2 {{variable can appear only once in OpenMP 'target update' construct}} expected-note 2 {{used here}}
 #pragma omp target update to(t), to(t[:5]) // expected-error 2 {{variable can appear only once in OpenMP 'target update' construct}} expected-note 2 {{used here}}
 #pragma omp target update to(da)
 #pragma omp target update to(da[:4])
 
 #pragma omp target update to(x, a[:2]) // expected-error {{subscripted value is not an array or pointer}}
 #pragma omp target update to(x, c[:]) // expected-error {{subscripted value is not an array or pointer}}
 #pragma omp target update to(x, (m+1)[2]) // expected-error 2 {{expected expression containing only member accesses and/or array sections based on named variables}}
 #pragma omp target update to(s7.i, s7.a[:3])

 #pragma omp target update to(S2::S2sc)
 #pragma omp target update to(to)
 #pragma omp target update to(y x) // expected-error {{expected ',' or ')' in 'to' clause}}
 #pragma omp target update to(argc > 0 ? x : y) // expected-error {{expected expression containing only member accesses and/or array sections based on named variables}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(S1) // expected-error {{'S1' does not refer to a value}}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(a, b, c, d, f) // expected-error {{incomplete type 'S1' where a complete type is required}} expected-error 2 {{type 'S2' is not mappable to target}}
 #pragma omp target update to(ba) // expected-error 2 {{type 'S2' is not mappable to target}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
 #pragma omp target update to(h) // expected-error {{threadprivate variables are not allowed in 'to' clause}} expected-error {{expected at least one 'to' clause or 'from' clause specified to '#pragma omp target update'}}
-#pragma omp target update to(k), to(k) // expected-error {{variable can appear only once in OpenMP 'target update' construct}} expected-note {{used here}}
+#pragma omp target update to(k), from(k) // expected-error {{variable can appear only once in OpenMP 'target update' construct}} expected-note {{used here}}
 #pragma omp target update to(t), to(t[:5]) // expected-error {{variable can appear only once in OpenMP 'target update' construct}} expected-note {{used here}}
 #pragma omp target update to(da)
 #pragma omp target update to(da[:4])
 
 #pragma omp target update to(x, a[:2]) // expected-error {{subscripted value is not an array or pointer}}
 #pragma omp target update to(x, c[:]) // expected-error {{subscripted value is not an array or pointer}}
 #pragma omp target update to(x, (m+1)[2]) // expected-error {{expected expression containing only member accesses and/or array sections based on named variables}}
 #pragma omp target update to(s7.i, s7.a[:3])

tools/libclang/CIndex.cpp

void OMPClauseEnqueue::VisitOMPDistScheduleClause(
   VisitOMPClauseWithPreInit(C);
   Visitor->AddStmt(C->getChunkSize());
 }
 void OMPClauseEnqueue::VisitOMPDefaultmapClause(
     const OMPDefaultmapClause * /*C*/) {}
 void OMPClauseEnqueue::VisitOMPToClause(const OMPToClause *C) {
   VisitOMPClauseList(C);
 }
+void OMPClauseEnqueue::VisitOMPFromClause(const OMPFromClause *C) {
+  VisitOMPClauseList(C);
+}
 }
 
 void EnqueueVisitor::EnqueueChildren(const OMPClause *S) {
   unsigned size = WL.size();
   OMPClauseEnqueue Visitor(this);
   Visitor.Visit(S);
   if (size == WL.size())
     return;