[OPENMP, NVPTX] Reduce the number of the globalized variables.

Patch tries to make better analysis of the variables that should be
globalized. From now, instead of all parallel directives it will check
only distribute parallel .. directives and check only for
firstprivte/lastprivate variables if they must be globalized.

llvm-svn: 335632

1 files changed, 43 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
index 5b7f0c3e43c..8cf5bb2f44b 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
@@ -187,7 +187,7 @@ class CheckVarsEscapingDeclContext final
   RecordDecl *GlobalizedRD = nullptr;
   llvm::SmallDenseMap<const ValueDecl *, const FieldDecl *> MappedDeclsFields;
   bool AllEscaped = false;
-  bool IsForParallelRegion = false;
+  bool IsForCombinedParallelRegion = false;
 
   static llvm::Optional<OMPDeclareTargetDeclAttr::MapTypeTy>
   isDeclareTargetDeclaration(const ValueDecl *VD) {
@@ -210,7 +210,7 @@ class CheckVarsEscapingDeclContext final
       if (const FieldDecl *FD = CSI->lookup(cast<VarDecl>(VD))) {
         // Check if need to capture the variable that was already captured by
         // value in the outer region.
-        if (!IsForParallelRegion) {
+        if (!IsForCombinedParallelRegion) {
           if (!FD->hasAttrs())
             return;
           const auto *Attr = FD->getAttr<OMPCaptureKindAttr>();
@@ -225,13 +225,13 @@ class CheckVarsEscapingDeclContext final
           assert(!VD->getType()->isVariablyModifiedType() &&
                  "Parameter captured by value with variably modified type");
           EscapedParameters.insert(VD);
-        } else if (!IsForParallelRegion) {
+        } else if (!IsForCombinedParallelRegion) {
           return;
         }
       }
     }
     if ((!CGF.CapturedStmtInfo ||
-         (IsForParallelRegion && CGF.CapturedStmtInfo)) &&
+         (IsForCombinedParallelRegion && CGF.CapturedStmtInfo)) &&
         VD->getType()->isReferenceType())
       // Do not globalize variables with reference type.
       return;
@@ -253,18 +253,49 @@ class CheckVarsEscapingDeclContext final
       }
     }
   }
-  void VisitOpenMPCapturedStmt(const CapturedStmt *S, bool IsParallelRegion) {
+  void VisitOpenMPCapturedStmt(const CapturedStmt *S,
+                               ArrayRef<OMPClause *> Clauses,
+                               bool IsCombinedParallelRegion) {
     if (!S)
       return;
     for (const CapturedStmt::Capture &C : S->captures()) {
       if (C.capturesVariable() && !C.capturesVariableByCopy()) {
         const ValueDecl *VD = C.getCapturedVar();
-        bool SavedIsParallelRegion = IsForParallelRegion;
-        IsForParallelRegion = IsParallelRegion;
+        bool SavedIsForCombinedParallelRegion = IsForCombinedParallelRegion;
+        if (IsCombinedParallelRegion) {
+          // Check if the variable is privatized in the combined construct and
+          // those private copies must be shared in the inner parallel
+          // directive.
+          IsForCombinedParallelRegion = false;
+          for (const OMPClause *C : Clauses) {
+            if (!isOpenMPPrivate(C->getClauseKind()) ||
+                C->getClauseKind() == OMPC_reduction ||
+                C->getClauseKind() == OMPC_linear ||
+                C->getClauseKind() == OMPC_private)
+              continue;
+            ArrayRef<const Expr *> Vars;
+            if (const auto *PC = dyn_cast<OMPFirstprivateClause>(C))
+              Vars = PC->getVarRefs();
+            else if (const auto *PC = dyn_cast<OMPLastprivateClause>(C))
+              Vars = PC->getVarRefs();
+            else
+              llvm_unreachable("Unexpected clause.");
+            for (const auto *E : Vars) {
+              const Decl *D =
+                  cast<DeclRefExpr>(E)->getDecl()->getCanonicalDecl();
+              if (D == VD->getCanonicalDecl()) {
+                IsForCombinedParallelRegion = true;
+                break;
+              }
+            }
+            if (IsForCombinedParallelRegion)
+              break;
+          }
+        }
         markAsEscaped(VD);
         if (isa<OMPCapturedExprDecl>(VD))
           VisitValueDecl(VD);
-        IsForParallelRegion = SavedIsParallelRegion;
+        IsForCombinedParallelRegion = SavedIsForCombinedParallelRegion;
       }
     }
   }
@@ -341,7 +372,10 @@ public:
         VisitStmt(S->getCapturedStmt());
         return;
       }
-      VisitOpenMPCapturedStmt(S, CaptureRegions.back() == OMPD_parallel);
+      VisitOpenMPCapturedStmt(
+          S, D->clauses(),
+          CaptureRegions.back() == OMPD_parallel &&
+              isOpenMPDistributeDirective(D->getDirectiveKind()));
     }
   }
   void VisitCapturedStmt(const CapturedStmt *S) {