[OPENMP]Provide correct data sharing attributes for loop control

variables.

Loop control variables are private in loop-based constructs and we shall
take this into account when generate the code for inner constructs.
Currently, those variables are reported as shared in many cases. Moved
the analysis of the data-sharing attributes of the loop control variable
to an early semantic stage to correctly handle their attributes.

llvm-svn: 366474

1 files changed, 55 insertions, 45 deletions

diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index bd68011c18b..bec2fd8d3c0 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -139,6 +139,7 @@ private:
     /// clause, false otherwise.
     llvm::Optional<std::pair<const Expr *, OMPOrderedClause *>> OrderedRegion;
     unsigned AssociatedLoops = 1;
+    bool HasMutipleLoops = false;
     const Decl *PossiblyLoopCounter = nullptr;
     bool NowaitRegion = false;
     bool CancelRegion = false;
@@ -678,12 +679,19 @@ public:
   /// Set collapse value for the region.
   void setAssociatedLoops(unsigned Val) {
     getTopOfStack().AssociatedLoops = Val;
+    if (Val > 1)
+      getTopOfStack().HasMutipleLoops = true;
   }
   /// Return collapse value for region.
   unsigned getAssociatedLoops() const {
     const SharingMapTy *Top = getTopOfStackOrNull();
     return Top ? Top->AssociatedLoops : 0;
   }
+  /// Returns true if the construct is associated with multiple loops.
+  bool hasMutipleLoops() const {
+    const SharingMapTy *Top = getTopOfStackOrNull();
+    return Top ? Top->HasMutipleLoops : false;
+  }
 
   /// Marks current target region as one with closely nested teams
   /// region.
@@ -5604,13 +5612,14 @@ void Sema::ActOnOpenMPLoopInitialization(SourceLocation ForLoc, Stmt *Init) {
     if (!ISC.checkAndSetInit(Init, /*EmitDiags=*/false)) {
       if (ValueDecl *D = ISC.getLoopDecl()) {
         auto *VD = dyn_cast<VarDecl>(D);
+        DeclRefExpr *PrivateRef = nullptr;
         if (!VD) {
           if (VarDecl *Private = isOpenMPCapturedDecl(D)) {
             VD = Private;
           } else {
-            DeclRefExpr *Ref = buildCapture(*this, D, ISC.getLoopDeclRefExpr(),
-                                            /*WithInit=*/false);
-            VD = cast<VarDecl>(Ref->getDecl());
+            PrivateRef = buildCapture(*this, D, ISC.getLoopDeclRefExpr(),
+                                      /*WithInit=*/false);
+            VD = cast<VarDecl>(PrivateRef->getDecl());
           }
         }
         DSAStack->addLoopControlVariable(D, VD);
@@ -5623,6 +5632,49 @@ void Sema::ActOnOpenMPLoopInitialization(SourceLocation ForLoc, Stmt *Init) {
                                  Var->getType().getNonLValueExprType(Context),
                                  ForLoc, /*RefersToCapture=*/true));
         }
+        OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
+        // OpenMP [2.14.1.1, Data-sharing Attribute Rules for Variables
+        // Referenced in a Construct, C/C++]. The loop iteration variable in the
+        // associated for-loop of a simd construct with just one associated
+        // for-loop may be listed in a linear clause with a constant-linear-step
+        // that is the increment of the associated for-loop. The loop iteration
+        // variable(s) in the associated for-loop(s) of a for or parallel for
+        // construct may be listed in a private or lastprivate clause.
+        DSAStackTy::DSAVarData DVar =
+            DSAStack->getTopDSA(D, /*FromParent=*/false);
+        // If LoopVarRefExpr is nullptr it means the corresponding loop variable
+        // is declared in the loop and it is predetermined as a private.
+        Expr *LoopDeclRefExpr = ISC.getLoopDeclRefExpr();
+        OpenMPClauseKind PredeterminedCKind =
+            isOpenMPSimdDirective(DKind)
+                ? (DSAStack->hasMutipleLoops() ? OMPC_lastprivate : OMPC_linear)
+                : OMPC_private;
+        if (((isOpenMPSimdDirective(DKind) && DVar.CKind != OMPC_unknown &&
+              DVar.CKind != PredeterminedCKind && DVar.RefExpr &&
+              (LangOpts.OpenMP <= 45 || (DVar.CKind != OMPC_lastprivate &&
+                                         DVar.CKind != OMPC_private))) ||
+             ((isOpenMPWorksharingDirective(DKind) || DKind == OMPD_taskloop ||
+               isOpenMPDistributeDirective(DKind)) &&
+              !isOpenMPSimdDirective(DKind) && DVar.CKind != OMPC_unknown &&
+              DVar.CKind != OMPC_private && DVar.CKind != OMPC_lastprivate)) &&
+            (DVar.CKind != OMPC_private || DVar.RefExpr)) {
+          Diag(Init->getBeginLoc(), diag::err_omp_loop_var_dsa)
+              << getOpenMPClauseName(DVar.CKind)
+              << getOpenMPDirectiveName(DKind)
+              << getOpenMPClauseName(PredeterminedCKind);
+          if (DVar.RefExpr == nullptr)
+            DVar.CKind = PredeterminedCKind;
+          reportOriginalDsa(*this, DSAStack, D, DVar,
+                            /*IsLoopIterVar=*/true);
+        } else if (LoopDeclRefExpr) {
+          // Make the loop iteration variable private (for worksharing
+          // constructs), linear (for simd directives with the only one
+          // associated loop) or lastprivate (for simd directives with several
+          // collapsed or ordered loops).
+          if (DVar.CKind == OMPC_unknown)
+            DSAStack->addDSA(D, LoopDeclRefExpr, PredeterminedCKind,
+                             PrivateRef);
+        }
       }
     }
     DSAStack->setAssociatedLoops(AssociatedLoops - 1);
@@ -5677,8 +5729,6 @@ static bool checkOpenMPIterationSpace(
 
   // Check loop variable's type.
   if (ValueDecl *LCDecl = ISC.getLoopDecl()) {
-    Expr *LoopDeclRefExpr = ISC.getLoopDeclRefExpr();
-
     // OpenMP [2.6, Canonical Loop Form]
     // Var is one of the following:
     //   A variable of signed or unsigned integer type.
@@ -5704,46 +5754,6 @@ static bool checkOpenMPIterationSpace(
     // sharing attributes.
     VarsWithImplicitDSA.erase(LCDecl);
 
-    // OpenMP [2.14.1.1, Data-sharing Attribute Rules for Variables Referenced
-    // in a Construct, C/C++].
-    // The loop iteration variable in the associated for-loop of a simd
-    // construct with just one associated for-loop may be listed in a linear
-    // clause with a constant-linear-step that is the increment of the
-    // associated for-loop.
-    // The loop iteration variable(s) in the associated for-loop(s) of a for or
-    // parallel for construct may be listed in a private or lastprivate clause.
-    DSAStackTy::DSAVarData DVar = DSA.getTopDSA(LCDecl, false);
-    // If LoopVarRefExpr is nullptr it means the corresponding loop variable is
-    // declared in the loop and it is predetermined as a private.
-    OpenMPClauseKind PredeterminedCKind =
-        isOpenMPSimdDirective(DKind)
-            ? ((NestedLoopCount == 1) ? OMPC_linear : OMPC_lastprivate)
-            : OMPC_private;
-    if (((isOpenMPSimdDirective(DKind) && DVar.CKind != OMPC_unknown &&
-          DVar.CKind != PredeterminedCKind && DVar.RefExpr &&
-          (SemaRef.getLangOpts().OpenMP <= 45 ||
-           (DVar.CKind != OMPC_lastprivate && DVar.CKind != OMPC_private))) ||
-         ((isOpenMPWorksharingDirective(DKind) || DKind == OMPD_taskloop ||
-           isOpenMPDistributeDirective(DKind)) &&
-          !isOpenMPSimdDirective(DKind) && DVar.CKind != OMPC_unknown &&
-          DVar.CKind != OMPC_private && DVar.CKind != OMPC_lastprivate)) &&
-        (DVar.CKind != OMPC_private || DVar.RefExpr)) {
-      SemaRef.Diag(Init->getBeginLoc(), diag::err_omp_loop_var_dsa)
-          << getOpenMPClauseName(DVar.CKind) << getOpenMPDirectiveName(DKind)
-          << getOpenMPClauseName(PredeterminedCKind);
-      if (DVar.RefExpr == nullptr)
-        DVar.CKind = PredeterminedCKind;
-      reportOriginalDsa(SemaRef, &DSA, LCDecl, DVar, /*IsLoopIterVar=*/true);
-      HasErrors = true;
-    } else if (LoopDeclRefExpr != nullptr) {
-      // Make the loop iteration variable private (for worksharing constructs),
-      // linear (for simd directives with the only one associated loop) or
-      // lastprivate (for simd directives with several collapsed or ordered
-      // loops).
-      if (DVar.CKind == OMPC_unknown)
-        DSA.addDSA(LCDecl, LoopDeclRefExpr, PredeterminedCKind);
-    }
-
     assert(isOpenMPLoopDirective(DKind) && "DSA for non-loop vars");
 
     // Check test-expr.