[clang][OpenMP] Move "loop" directive mapping from sema to codegen (#99905)

Given "loop" construct, clang will try to treat it as "for",
"distribute" or "simd", depending on either the implied binding, or the
bind clause if present. This patch moves the code that performs this
construct remapping from sema to codegen.

For a "loop" construct without a bind clause, this patch will create an
implicit bind clause based on implied binding to simplify further
analysis.

During codegen the function `EmitOMPGenericLoopDirective` (i.e. "loop")
will invoke the "emit" functions for "for", "distribute" or "simd",
depending on the bind clause.

---------

Co-authored-by: Alexey Bataev <[email protected]>

Author: kparzysz

clang/include/clang/AST/StmtOpenMP.h

@@ -281,15 +281,6 @@ class OMPExecutableDirective : public Stmt {
     return Data->getClauses();
   }
 
-  /// Was this directive mapped from an another directive?
-  /// e.g. 1) omp loop bind(parallel) is mapped to OMPD_for
-  ///      2) omp loop bind(teams) is mapped to OMPD_distribute
-  ///      3) omp loop bind(thread) is mapped to OMPD_simd
-  /// It was necessary to note it down in the Directive because of
-  /// clang::TreeTransform::TransformOMPExecutableDirective() pass in
-  /// the frontend.
-  OpenMPDirectiveKind PrevMappedDirective = llvm::omp::OMPD_unknown;
-
 protected:
   /// Data, associated with the directive.
   OMPChildren *Data = nullptr;
@@ -354,10 +345,6 @@ class OMPExecutableDirective : public Stmt {
     return Inst;
   }
 
-  void setMappedDirective(OpenMPDirectiveKind MappedDirective) {
-    PrevMappedDirective = MappedDirective;
-  }
-
 public:
   /// Iterates over expressions/statements used in the construct.
   class used_clauses_child_iterator
@@ -611,8 +598,6 @@ class OMPExecutableDirective : public Stmt {
            "Expected directive with the associated statement.");
     return Data->getRawStmt();
   }
-
-  OpenMPDirectiveKind getMappedDirective() const { return PrevMappedDirective; }
 };
 
 /// This represents '#pragma omp parallel' directive.
@@ -1620,8 +1605,7 @@ class OMPSimdDirective : public OMPLoopDirective {
                                   SourceLocation EndLoc, unsigned CollapsedNum,
                                   ArrayRef<OMPClause *> Clauses,
                                   Stmt *AssociatedStmt,
-                                  const HelperExprs &Exprs,
-                                  OpenMPDirectiveKind ParamPrevMappedDirective);
+                                  const HelperExprs &Exprs);
 
   /// Creates an empty directive with the place
   /// for \a NumClauses clauses.
@@ -1699,8 +1683,7 @@ class OMPForDirective : public OMPLoopDirective {
                                  SourceLocation EndLoc, unsigned CollapsedNum,
                                  ArrayRef<OMPClause *> Clauses,
                                  Stmt *AssociatedStmt, const HelperExprs &Exprs,
-                                 Expr *TaskRedRef, bool HasCancel,
-                                 OpenMPDirectiveKind ParamPrevMappedDirective);
+                                 Expr *TaskRedRef, bool HasCancel);
 
   /// Creates an empty directive with the place
   /// for \a NumClauses clauses.
@@ -4478,8 +4461,7 @@ class OMPDistributeDirective : public OMPLoopDirective {
   static OMPDistributeDirective *
   Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
          unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses,
-         Stmt *AssociatedStmt, const HelperExprs &Exprs,
-         OpenMPDirectiveKind ParamPrevMappedDirective);
+         Stmt *AssociatedStmt, const HelperExprs &Exprs);
 
   /// Creates an empty directive with the place
   /// for \a NumClauses clauses.

clang/include/clang/Sema/SemaOpenMP.h

@@ -398,8 +398,7 @@ class SemaOpenMP : public SemaBase {
   StmtResult ActOnOpenMPExecutableDirective(
       OpenMPDirectiveKind Kind, const DeclarationNameInfo &DirName,
       OpenMPDirectiveKind CancelRegion, ArrayRef<OMPClause *> Clauses,
-      Stmt *AStmt, SourceLocation StartLoc, SourceLocation EndLoc,
-      OpenMPDirectiveKind PrevMappedDirective = llvm::omp::OMPD_unknown);
+      Stmt *AStmt, SourceLocation StartLoc, SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp parallel' after parsing
   /// of the  associated statement.
   StmtResult ActOnOpenMPParallelDirective(ArrayRef<OMPClause *> Clauses,
@@ -1430,26 +1429,6 @@ class SemaOpenMP : public SemaBase {
 
   /// All `omp assumes` we encountered so far.
   SmallVector<OMPAssumeAttr *, 4> OMPAssumeGlobal;
-
-  /// OMPD_loop is mapped to OMPD_for, OMPD_distribute or OMPD_simd depending
-  /// on the parameter of the bind clause. In the methods for the
-  /// mapped directives, check the parameters of the lastprivate clause.
-  bool checkLastPrivateForMappedDirectives(ArrayRef<OMPClause *> Clauses);
-  /// Depending on the bind clause of OMPD_loop map the directive to new
-  /// directives.
-  ///    1) loop bind(parallel) --> OMPD_for
-  ///    2) loop bind(teams) --> OMPD_distribute
-  ///    3) loop bind(thread) --> OMPD_simd
-  /// This is being handled in Sema instead of Codegen because of the need for
-  /// rigorous semantic checking in the new mapped directives.
-  bool mapLoopConstruct(llvm::SmallVector<OMPClause *> &ClausesWithoutBind,
-                        ArrayRef<OMPClause *> Clauses,
-                        OpenMPBindClauseKind &BindKind,
-                        OpenMPDirectiveKind &Kind,
-                        OpenMPDirectiveKind &PrevMappedDirective,
-                        SourceLocation StartLoc, SourceLocation EndLoc,
-                        const DeclarationNameInfo &DirName,
-                        OpenMPDirectiveKind CancelRegion);
 };
 
 } // namespace clang

clang/lib/AST/StmtOpenMP.cpp

@@ -297,10 +297,11 @@ OMPParallelDirective *OMPParallelDirective::CreateEmpty(const ASTContext &C,
                                                     /*NumChildren=*/1);
 }
 
-OMPSimdDirective *OMPSimdDirective::Create(
-    const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
-    unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
-    const HelperExprs &Exprs, OpenMPDirectiveKind ParamPrevMappedDirective) {
+OMPSimdDirective *
+OMPSimdDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+                         SourceLocation EndLoc, unsigned CollapsedNum,
+                         ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
+                         const HelperExprs &Exprs) {
   auto *Dir = createDirective<OMPSimdDirective>(
       C, Clauses, AssociatedStmt, numLoopChildren(CollapsedNum, OMPD_simd),
       StartLoc, EndLoc, CollapsedNum);
@@ -320,7 +321,6 @@ OMPSimdDirective *OMPSimdDirective::Create(
   Dir->setDependentInits(Exprs.DependentInits);
   Dir->setFinalsConditions(Exprs.FinalsConditions);
   Dir->setPreInits(Exprs.PreInits);
-  Dir->setMappedDirective(ParamPrevMappedDirective);
   return Dir;
 }
 
@@ -336,8 +336,7 @@ OMPSimdDirective *OMPSimdDirective::CreateEmpty(const ASTContext &C,
 OMPForDirective *OMPForDirective::Create(
     const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
     unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
-    const HelperExprs &Exprs, Expr *TaskRedRef, bool HasCancel,
-    OpenMPDirectiveKind ParamPrevMappedDirective) {
+    const HelperExprs &Exprs, Expr *TaskRedRef, bool HasCancel) {
   auto *Dir = createDirective<OMPForDirective>(
       C, Clauses, AssociatedStmt, numLoopChildren(CollapsedNum, OMPD_for) + 1,
       StartLoc, EndLoc, CollapsedNum);
@@ -367,7 +366,6 @@ OMPForDirective *OMPForDirective::Create(
   Dir->setPreInits(Exprs.PreInits);
   Dir->setTaskReductionRefExpr(TaskRedRef);
   Dir->setHasCancel(HasCancel);
-  Dir->setMappedDirective(ParamPrevMappedDirective);
   return Dir;
 }
 
@@ -1569,10 +1567,11 @@ OMPParallelMaskedTaskLoopSimdDirective::CreateEmpty(const ASTContext &C,
       CollapsedNum);
 }
 
-OMPDistributeDirective *OMPDistributeDirective::Create(
-    const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
-    unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
-    const HelperExprs &Exprs, OpenMPDirectiveKind ParamPrevMappedDirective) {
+OMPDistributeDirective *
+OMPDistributeDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+                               SourceLocation EndLoc, unsigned CollapsedNum,
+                               ArrayRef<OMPClause *> Clauses,
+                               Stmt *AssociatedStmt, const HelperExprs &Exprs) {
   auto *Dir = createDirective<OMPDistributeDirective>(
       C, Clauses, AssociatedStmt,
       numLoopChildren(CollapsedNum, OMPD_distribute), StartLoc, EndLoc,
@@ -1601,7 +1600,6 @@ OMPDistributeDirective *OMPDistributeDirective::Create(
   Dir->setDependentInits(Exprs.DependentInits);
   Dir->setFinalsConditions(Exprs.FinalsConditions);
   Dir->setPreInits(Exprs.PreInits);
-  Dir->setMappedDirective(ParamPrevMappedDirective);
   return Dir;
 }