[Clang] [OpenMP] Add support for '#pragma omp stripe'. (#119891)

Implement basic parsing and semantic support for `#pragma omp stripe`
constuct introduced in
https://www.openmp.org/wp-content/uploads/[OpenMP-API-Specification-6-0.pdf](https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-6-0.pdf),
section 11.7.

Author: zahiraam

clang/bindings/python/clang/cindex.py

@@ -1410,6 +1410,9 @@ def is_unexposed(self):
     # OpenMP scope directive.
     OMP_SCOPE_DIRECTIVE = 306
 
+    # OpenMP stripe directive.
+    OMP_STRIPE_DIRECTIVE = 310
+
     # OpenACC Compute Construct.
     OPEN_ACC_COMPUTE_DIRECTIVE = 320
 

clang/docs/OpenMPSupport.rst

@@ -374,6 +374,8 @@ implementation.
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | Loop transformation constructs                              | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
+| loop stripe transformation                                  | :good:`done`              | https://github.com/llvm/llvm-project/pull/119891                                                     |
++-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | work distribute construct                                   | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | task_iteration                                              | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |

clang/docs/ReleaseNotes.rst

@@ -291,6 +291,7 @@ Python Binding Changes
 OpenMP Support
 --------------
 - Added support 'no_openmp_constructs' assumption clause.
+- Added support for 'omp stripe' directive.
 
 Improvements
 ^^^^^^^^^^^^

clang/include/clang-c/Index.h

@@ -2158,6 +2158,10 @@ enum CXCursorKind {
    */
   CXCursor_OMPAssumeDirective = 309,
 
+  /** OpenMP assume directive.
+   */
+  CXCursor_OMPStripeDirective = 310,
+
   /** OpenACC Compute Construct.
    */
   CXCursor_OpenACCComputeConstruct = 320,

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -3056,6 +3056,9 @@ DEF_TRAVERSE_STMT(OMPSimdDirective,
 DEF_TRAVERSE_STMT(OMPTileDirective,
                   { TRY_TO(TraverseOMPExecutableDirective(S)); })
 
+DEF_TRAVERSE_STMT(OMPStripeDirective,
+                  { TRY_TO(TraverseOMPExecutableDirective(S)); })
+
 DEF_TRAVERSE_STMT(OMPUnrollDirective,
                   { TRY_TO(TraverseOMPExecutableDirective(S)); })
 

clang/include/clang/AST/StmtOpenMP.h

@@ -994,7 +994,9 @@ class OMPLoopTransformationDirective : public OMPLoopBasedDirective {
   static bool classof(const Stmt *T) {
     Stmt::StmtClass C = T->getStmtClass();
     return C == OMPTileDirectiveClass || C == OMPUnrollDirectiveClass ||
-           C == OMPReverseDirectiveClass || C == OMPInterchangeDirectiveClass;
+           C == OMPReverseDirectiveClass || C == OMPInterchangeDirectiveClass ||
+           C == OMPStripeDirectiveClass;
+    ;
   }
 };
 
@@ -5560,7 +5562,7 @@ class OMPTileDirective final : public OMPLoopTransformationDirective {
       : OMPLoopTransformationDirective(OMPTileDirectiveClass,
                                        llvm::omp::OMPD_tile, StartLoc, EndLoc,
                                        NumLoops) {
-    setNumGeneratedLoops(3 * NumLoops);
+    setNumGeneratedLoops(2 * NumLoops);
   }
 
   void setPreInits(Stmt *PreInits) {
@@ -5621,6 +5623,82 @@ class OMPTileDirective final : public OMPLoopTransformationDirective {
   }
 };
 
+/// This represents the '#pragma omp stripe' loop transformation directive.
+class OMPStripeDirective final : public OMPLoopTransformationDirective {
+  friend class ASTStmtReader;
+  friend class OMPExecutableDirective;
+
+  /// Default list of offsets.
+  enum {
+    PreInitsOffset = 0,
+    TransformedStmtOffset,
+  };
+
+  explicit OMPStripeDirective(SourceLocation StartLoc, SourceLocation EndLoc,
+                              unsigned NumLoops)
+      : OMPLoopTransformationDirective(OMPStripeDirectiveClass,
+                                       llvm::omp::OMPD_stripe, StartLoc, EndLoc,
+                                       NumLoops) {
+    setNumGeneratedLoops(2 * NumLoops);
+  }
+
+  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 stripe'.
+  ///
+  /// \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 Clauses   The directive's clauses.
+  /// \param NumLoops  Number of associated loops (number of items in the
+  ///                  'sizes' clause).
+  /// \param AssociatedStmt The outermost associated loop.
+  /// \param TransformedStmt The loop nest after striping, or nullptr in
+  ///                        dependent contexts.
+  /// \param PreInits Helper preinits statements for the loop nest.
+  static OMPStripeDirective *
+  Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+         ArrayRef<OMPClause *> Clauses, unsigned NumLoops, Stmt *AssociatedStmt,
+         Stmt *TransformedStmt, Stmt *PreInits);
+
+  /// Build an empty '#pragma omp stripe' AST node for deserialization.
+  ///
+  /// \param C          Context of the AST.
+  /// \param NumClauses Number of clauses to allocate.
+  /// \param NumLoops   Number of associated loops to allocate.
+  static OMPStripeDirective *
+  CreateEmpty(const ASTContext &C, unsigned NumClauses, unsigned NumLoops);
+
+  /// Gets/sets the associated loops after striping.
+  ///
+  /// This is in de-sugared format stored as a CompoundStmt.
+  ///
+  /// \code
+  ///   for (...)
+  ///     ...
+  /// \endcode
+  ///
+  /// Note that if the generated loops a become associated loops of another
+  /// directive, they may need to be hoisted before them.
+  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() == OMPStripeDirectiveClass;
+  }
+};
+
 /// This represents the '#pragma omp unroll' loop transformation directive.
 ///
 /// \code

clang/include/clang/Basic/StmtNodes.td

@@ -231,6 +231,7 @@ def OMPParallelDirective : StmtNode<OMPExecutableDirective>;
 def OMPSimdDirective : StmtNode<OMPLoopDirective>;
 def OMPLoopTransformationDirective : StmtNode<OMPLoopBasedDirective, 1>;
 def OMPTileDirective : StmtNode<OMPLoopTransformationDirective>;
+def OMPStripeDirective : StmtNode<OMPLoopTransformationDirective>;
 def OMPUnrollDirective : StmtNode<OMPLoopTransformationDirective>;
 def OMPReverseDirective : StmtNode<OMPLoopTransformationDirective>;
 def OMPInterchangeDirective : StmtNode<OMPLoopTransformationDirective>;

clang/include/clang/Sema/SemaOpenMP.h

@@ -440,6 +440,9 @@ class SemaOpenMP : public SemaBase {
   StmtResult ActOnOpenMPTileDirective(ArrayRef<OMPClause *> Clauses,
                                       Stmt *AStmt, SourceLocation StartLoc,
                                       SourceLocation EndLoc);
+  StmtResult ActOnOpenMPStripeDirective(ArrayRef<OMPClause *> Clauses,
+                                        Stmt *AStmt, SourceLocation StartLoc,
+                                        SourceLocation EndLoc);
   /// Called on well-formed '#pragma omp unroll' after parsing of its clauses
   /// and the associated statement.
   StmtResult ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,

clang/include/clang/Serialization/ASTBitCodes.h

@@ -1939,6 +1939,7 @@ enum StmtCode {
   STMT_OMP_PARALLEL_DIRECTIVE,
   STMT_OMP_SIMD_DIRECTIVE,
   STMT_OMP_TILE_DIRECTIVE,
+  STMP_OMP_STRIPE_DIRECTIVE,
   STMT_OMP_UNROLL_DIRECTIVE,
   STMT_OMP_REVERSE_DIRECTIVE,
   STMT_OMP_INTERCHANGE_DIRECTIVE,

clang/lib/AST/StmtOpenMP.cpp

@@ -417,6 +417,27 @@ OMPTileDirective::Create(const ASTContext &C, SourceLocation StartLoc,
   return Dir;
 }
 
+OMPStripeDirective *
+OMPStripeDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+                           SourceLocation EndLoc, ArrayRef<OMPClause *> Clauses,
+                           unsigned NumLoops, Stmt *AssociatedStmt,
+                           Stmt *TransformedStmt, Stmt *PreInits) {
+  OMPStripeDirective *Dir = createDirective<OMPStripeDirective>(
+      C, Clauses, AssociatedStmt, TransformedStmtOffset + 1, StartLoc, EndLoc,
+      NumLoops);
+  Dir->setTransformedStmt(TransformedStmt);
+  Dir->setPreInits(PreInits);
+  return Dir;
+}
+
+OMPStripeDirective *OMPStripeDirective::CreateEmpty(const ASTContext &C,
+                                                    unsigned NumClauses,
+                                                    unsigned NumLoops) {
+  return createEmptyDirective<OMPStripeDirective>(
+      C, NumClauses, /*HasAssociatedStmt=*/true, TransformedStmtOffset + 1,
+      SourceLocation(), SourceLocation(), NumLoops);
+}
+
 OMPTileDirective *OMPTileDirective::CreateEmpty(const ASTContext &C,
                                                 unsigned NumClauses,
                                                 unsigned NumLoops) {