[Clang][OpenMP] Add reverse directive

clang/include/clang-c/Index.h

@@ -2146,6 +2146,10 @@ enum CXCursorKind {
    */
   CXCursor_OMPScopeDirective = 306,
 
+  /** OpenMP reverse directive.
+   */
+  CXCursor_OMPReverseDirective = 307,
+
   /** OpenACC Compute Construct.
    */
   CXCursor_OpenACCComputeConstruct = 320,

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -3032,6 +3032,9 @@ DEF_TRAVERSE_STMT(OMPTileDirective,
 DEF_TRAVERSE_STMT(OMPUnrollDirective,
                   { TRY_TO(TraverseOMPExecutableDirective(S)); })
 
+DEF_TRAVERSE_STMT(OMPReverseDirective,
+                  { TRY_TO(TraverseOMPExecutableDirective(S)); })
+
 DEF_TRAVERSE_STMT(OMPForDirective,
                   { TRY_TO(TraverseOMPExecutableDirective(S)); })
 

clang/include/clang/AST/StmtOpenMP.h

@@ -1007,8 +1007,9 @@ class OMPLoopTransformationDirective : public OMPLoopBasedDirective {
   Stmt *getPreInits() const;
 
   static bool classof(const Stmt *T) {
-    return T->getStmtClass() == OMPTileDirectiveClass ||
-           T->getStmtClass() == OMPUnrollDirectiveClass;
+    Stmt::StmtClass C = T->getStmtClass();
+    return C == OMPTileDirectiveClass || C == OMPUnrollDirectiveClass ||
+           C == OMPReverseDirectiveClass;
   }
 };
 
@@ -5711,6 +5712,70 @@ class OMPUnrollDirective final : public OMPLoopTransformationDirective {
   }
 };
 
+/// Represents the '#pragma omp reverse' loop transformation directive.
+///
+/// \code
+/// #pragma omp reverse
+/// for (int i = 0; i < n; ++i)
+///   ...
+/// \endcode
+class OMPReverseDirective final : public OMPLoopTransformationDirective {
+  friend class ASTStmtReader;
+  friend class OMPExecutableDirective;
+
+  /// Offsets of child members.
+  enum {
+    PreInitsOffset = 0,
+    TransformedStmtOffset,
+  };
+
+  explicit OMPReverseDirective(SourceLocation StartLoc, SourceLocation EndLoc)
+      : OMPLoopTransformationDirective(OMPReverseDirectiveClass,
+                                       llvm::omp::OMPD_reverse, StartLoc,
+                                       EndLoc, 1) {}
+
+  void setPreInits(Stmt *PreInits) {
+    Data->getChildren()[PreInitsOffset] = PreInits;
+  }
+
+  void setTransformedStmt(Stmt *S) {
+    Data->getChildren()[TransformedStmtOffset] = S;
+  }
+
+public:
+  /// Create a new AST node representation for '#pragma omp reverse'.
+  ///
+  /// \param C         Context of the AST.
+  /// \param StartLoc  Location of the introducer (e.g. the 'omp' token).
+  /// \param EndLoc    Location of the directive's end (e.g. the tok::eod).
+  /// \param AssociatedStmt  The outermost associated loop.
+  /// \param TransformedStmt The loop nest after tiling, or nullptr in
+  ///                        dependent contexts.
+  /// \param PreInits   Helper preinits statements for the loop nest.
+  static OMPReverseDirective *
+  Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+         Stmt *AssociatedStmt, Stmt *TransformedStmt, Stmt *PreInits);
+
+  /// Build an empty '#pragma omp reverse' AST node for deserialization.
+  ///
+  /// \param C          Context of the AST.
+  /// \param NumClauses Number of clauses to allocate.
+  static OMPReverseDirective *CreateEmpty(const ASTContext &C);
+
+  /// Gets/sets the associated loops after the transformation, i.e. after
+  /// de-sugaring.
+  Stmt *getTransformedStmt() const {
+    return Data->getChildren()[TransformedStmtOffset];
+  }
+
+  /// Return preinits statement.
+  Stmt *getPreInits() const { return Data->getChildren()[PreInitsOffset]; }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == OMPReverseDirectiveClass;
+  }
+};
+
 /// This represents '#pragma omp scan' directive.
 ///
 /// \code

clang/include/clang/Basic/StmtNodes.td

@@ -230,6 +230,7 @@ def OMPSimdDirective : StmtNode<OMPLoopDirective>;
 def OMPLoopTransformationDirective : StmtNode<OMPLoopBasedDirective, 1>;
 def OMPTileDirective : StmtNode<OMPLoopTransformationDirective>;
 def OMPUnrollDirective : StmtNode<OMPLoopTransformationDirective>;
+def OMPReverseDirective : StmtNode<OMPLoopTransformationDirective>;
 def OMPForDirective : StmtNode<OMPLoopDirective>;
 def OMPForSimdDirective : StmtNode<OMPLoopDirective>;
 def OMPSectionsDirective : StmtNode<OMPExecutableDirective>;

clang/include/clang/Sema/SemaOpenMP.h

@@ -423,6 +423,9 @@ class SemaOpenMP : public SemaBase {
   StmtResult ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
+  /// Called on well-formed '#pragma omp reverse'.
+  StmtResult ActOnOpenMPReverseDirective(Stmt *AStmt, SourceLocation StartLoc,
+                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp for' after parsing
   /// of the associated statement.
   StmtResult

clang/include/clang/Serialization/ASTBitCodes.h

@@ -1895,6 +1895,7 @@ enum StmtCode {
   STMT_OMP_SIMD_DIRECTIVE,
   STMT_OMP_TILE_DIRECTIVE,
   STMT_OMP_UNROLL_DIRECTIVE,
+  STMT_OMP_REVERSE_DIRECTIVE,
   STMT_OMP_FOR_DIRECTIVE,
   STMT_OMP_FOR_SIMD_DIRECTIVE,
   STMT_OMP_SECTIONS_DIRECTIVE,

clang/lib/AST/StmtOpenMP.cpp

@@ -449,6 +449,24 @@ OMPUnrollDirective *OMPUnrollDirective::CreateEmpty(const ASTContext &C,
       SourceLocation(), SourceLocation());
 }
 
+OMPReverseDirective *
+OMPReverseDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+                            SourceLocation EndLoc, Stmt *AssociatedStmt,
+                            Stmt *TransformedStmt, Stmt *PreInits) {
+  OMPReverseDirective *Dir = createDirective<OMPReverseDirective>(
+      C, std::nullopt, AssociatedStmt, TransformedStmtOffset + 1, StartLoc,
+      EndLoc);
+  Dir->setTransformedStmt(TransformedStmt);
+  Dir->setPreInits(PreInits);
+  return Dir;
+}
+
+OMPReverseDirective *OMPReverseDirective::CreateEmpty(const ASTContext &C) {
+  return createEmptyDirective<OMPReverseDirective>(
+      C, /*NumClauses=*/0, /*HasAssociatedStmt=*/true,
+      TransformedStmtOffset + 1, SourceLocation(), SourceLocation());
+}
+
 OMPForSimdDirective *
 OMPForSimdDirective::Create(const ASTContext &C, SourceLocation StartLoc,
                             SourceLocation EndLoc, unsigned CollapsedNum,

clang/lib/AST/StmtPrinter.cpp

@@ -763,6 +763,11 @@ void StmtPrinter::VisitOMPUnrollDirective(OMPUnrollDirective *Node) {
   PrintOMPExecutableDirective(Node);
 }
 
+void StmtPrinter::VisitOMPReverseDirective(OMPReverseDirective *Node) {
+  Indent() << "#pragma omp reverse";
+  PrintOMPExecutableDirective(Node);
+}
+
 void StmtPrinter::VisitOMPForDirective(OMPForDirective *Node) {
   Indent() << "#pragma omp for";
   PrintOMPExecutableDirective(Node);

clang/lib/AST/StmtProfile.cpp

@@ -985,6 +985,10 @@ void StmtProfiler::VisitOMPUnrollDirective(const OMPUnrollDirective *S) {
   VisitOMPLoopTransformationDirective(S);
 }
 
+void StmtProfiler::VisitOMPReverseDirective(const OMPReverseDirective *S) {
+  VisitOMPLoopTransformationDirective(S);
+}
+
 void StmtProfiler::VisitOMPForDirective(const OMPForDirective *S) {
   VisitOMPLoopDirective(S);
 }

clang/lib/Basic/OpenMPKinds.cpp

@@ -684,7 +684,7 @@ bool clang::isOpenMPLoopBoundSharingDirective(OpenMPDirectiveKind Kind) {
 }
 
 bool clang::isOpenMPLoopTransformationDirective(OpenMPDirectiveKind DKind) {
-  return DKind == OMPD_tile || DKind == OMPD_unroll;
+  return DKind == OMPD_tile || DKind == OMPD_unroll || DKind == OMPD_reverse;
 }
 
 bool clang::isOpenMPCombinedParallelADirective(OpenMPDirectiveKind DKind) {

clang/lib/CodeGen/CGStmt.cpp

@@ -222,6 +222,9 @@ void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
   case Stmt::OMPUnrollDirectiveClass:
     EmitOMPUnrollDirective(cast<OMPUnrollDirective>(*S));
     break;
+  case Stmt::OMPReverseDirectiveClass:
+    EmitOMPReverseDirective(cast<OMPReverseDirective>(*S));
+    break;
   case Stmt::OMPForDirectiveClass:
     EmitOMPForDirective(cast<OMPForDirective>(*S));
     break;

clang/lib/CodeGen/CGStmtOpenMP.cpp

@@ -187,6 +187,8 @@ class OMPLoopScope : public CodeGenFunction::RunCleanupsScope {
       PreInits = Tile->getPreInits();
     } else if (const auto *Unroll = dyn_cast<OMPUnrollDirective>(&S)) {
       PreInits = Unroll->getPreInits();
+    } else if (const auto *Reverse = dyn_cast<OMPReverseDirective>(&S)) {
+      PreInits = Reverse->getPreInits();
     } else {
       llvm_unreachable("Unknown loop-based directive kind.");
     }
@@ -2762,6 +2764,12 @@ void CodeGenFunction::EmitOMPTileDirective(const OMPTileDirective &S) {
   EmitStmt(S.getTransformedStmt());
 }
 
+void CodeGenFunction::EmitOMPReverseDirective(const OMPReverseDirective &S) {
+  // Emit the de-sugared statement.
+  OMPTransformDirectiveScopeRAII ReverseScope(*this, &S);
+  EmitStmt(S.getTransformedStmt());
+}
+
 void CodeGenFunction::EmitOMPUnrollDirective(const OMPUnrollDirective &S) {
   bool UseOMPIRBuilder = CGM.getLangOpts().OpenMPIRBuilder;
 

clang/lib/CodeGen/CodeGenFunction.h

@@ -3817,6 +3817,7 @@ class CodeGenFunction : public CodeGenTypeCache {
   void EmitOMPSimdDirective(const OMPSimdDirective &S);
   void EmitOMPTileDirective(const OMPTileDirective &S);
   void EmitOMPUnrollDirective(const OMPUnrollDirective &S);
+  void EmitOMPReverseDirective(const OMPReverseDirective &S);
   void EmitOMPForDirective(const OMPForDirective &S);
   void EmitOMPForSimdDirective(const OMPForSimdDirective &S);
   void EmitOMPSectionsDirective(const OMPSectionsDirective &S);

clang/lib/Parse/ParseOpenMP.cpp

@@ -2885,6 +2885,7 @@ StmtResult Parser::ParseOpenMPDeclarativeOrExecutableDirective(
     }
     break;
   }
+  case OMPD_reverse:
   case OMPD_declare_target: {
     SourceLocation DTLoc = ConsumeAnyToken();
     bool HasClauses = Tok.isNot(tok::annot_pragma_openmp_end);

clang/lib/Sema/SemaExceptionSpec.cpp

@@ -1466,6 +1466,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Stmt::OMPSimdDirectiveClass:
   case Stmt::OMPTileDirectiveClass:
   case Stmt::OMPUnrollDirectiveClass:
+  case Stmt::OMPReverseDirectiveClass:
   case Stmt::OMPSingleDirectiveClass:
   case Stmt::OMPTargetDataDirectiveClass:
   case Stmt::OMPTargetDirectiveClass: