Reapply "[OpenACC] Sema changes for +*&|^ reduction combiner recipes (… (llvm/llvm-project#162920) (#163246)

This reverts commit
llvm/llvm-project@8d9aecc.

Additionally, this refactors how we're doing the AST storage to put it
all in the trailing storage, which will hopefully prevent it from
leaking. The problem was that the AST doesn't call destructors on things
in ASTContext storage, so we weren't actually able to delete the
combiner
SmallVector (which I should have known...). This patch instead moves all
of that SmallVector data into trailing storage, which shouldn't have the
same
problem with leaking as before.

Author: erichkeane

clang/include/clang/AST/OpenACCClause.h

@@ -1277,7 +1277,7 @@ class OpenACCCreateClause final
 };
 
 // A structure to stand in for the recipe on a reduction.  RecipeDecl is the
-// 'main' declaration used for initializaiton, which is fixed. 
+// 'main' declaration used for initializaiton, which is fixed.
 struct OpenACCReductionRecipe {
   VarDecl *AllocaDecl;
 
@@ -1297,36 +1297,69 @@ struct OpenACCReductionRecipe {
   // -For a struct without the operator, this will be 1 element per field, which
   //  should be the combiner for that element.
   // -For an array of any of the above, it will be the above for the element.
-  llvm::SmallVector<CombinerRecipe, 1> CombinerRecipes;
+  // Note: These are necessarily stored in either Trailing Storage (when in the
+  // AST), or in a separate collection when being semantically analyzed.
+  llvm::ArrayRef<CombinerRecipe> CombinerRecipes;
 
   OpenACCReductionRecipe(VarDecl *A, llvm::ArrayRef<CombinerRecipe> Combiners)
       : AllocaDecl(A), CombinerRecipes(Combiners) {}
 
   bool isSet() const { return AllocaDecl; }
-  static OpenACCReductionRecipe Empty() {
-    return OpenACCReductionRecipe(/*AllocaDecl=*/nullptr, {});
+};
+
+// A version of the above that is used for semantic analysis, at a time before
+// the OpenACCReductionClause node has been created.  This one has storage for
+// the CombinerRecipe, since Trailing storage for it doesn't exist yet.
+struct OpenACCReductionRecipeWithStorage : OpenACCReductionRecipe {
+  llvm::SmallVector<CombinerRecipe, 1> CombinerRecipeStorage;
+
+  OpenACCReductionRecipeWithStorage(VarDecl *A,
+                                    llvm::ArrayRef<CombinerRecipe> Combiners)
+      : OpenACCReductionRecipe(A, {}), CombinerRecipeStorage(Combiners) {
+    CombinerRecipes = CombinerRecipeStorage;
+  }
+  static OpenACCReductionRecipeWithStorage Empty() {
+    return OpenACCReductionRecipeWithStorage(/*AllocaDecl=*/nullptr, {});
   }
 };
 
 class OpenACCReductionClause final
     : public OpenACCClauseWithVarList,
       private llvm::TrailingObjects<OpenACCReductionClause, Expr *,
-                                    OpenACCReductionRecipe> {
+                                    OpenACCReductionRecipe,
+                                    OpenACCReductionRecipe::CombinerRecipe> {
   friend TrailingObjects;
   OpenACCReductionOperator Op;
 
   OpenACCReductionClause(SourceLocation BeginLoc, SourceLocation LParenLoc,
                          OpenACCReductionOperator Operator,
                          ArrayRef<Expr *> VarList,
-                         ArrayRef<OpenACCReductionRecipe> Recipes,
+                         ArrayRef<OpenACCReductionRecipeWithStorage> Recipes,
                          SourceLocation EndLoc)
       : OpenACCClauseWithVarList(OpenACCClauseKind::Reduction, BeginLoc,
                                  LParenLoc, EndLoc),
         Op(Operator) {
-          assert(VarList.size() == Recipes.size());
+    assert(VarList.size() == Recipes.size());
     setExprs(getTrailingObjects<Expr *>(VarList.size()), VarList);
-    llvm::uninitialized_copy(Recipes, getTrailingObjects<
-                             OpenACCReductionRecipe > ());
+
+    // Since we're using trailing storage on this node to store the 'combiner'
+    // recipes of the Reduction Recipes (which have a 1:M relationship), we need
+    // to ensure we get the ArrayRef of each of our combiner 'correct'.
+    OpenACCReductionRecipe::CombinerRecipe *CurCombinerLoc =
+        getTrailingObjects<OpenACCReductionRecipe::CombinerRecipe>();
+    for (const auto &[Idx, R] : llvm::enumerate(Recipes)) {
+
+      // ArrayRef to the 'correct' data location in trailing storage.
+      llvm::MutableArrayRef<OpenACCReductionRecipe::CombinerRecipe>
+          NewCombiners{CurCombinerLoc, R.CombinerRecipes.size()};
+      CurCombinerLoc += R.CombinerRecipes.size();
+
+      llvm::uninitialized_copy(R.CombinerRecipes, NewCombiners.begin());
+
+      // Placement new into the correct location in trailng storage.
+      new (&getTrailingObjects<OpenACCReductionRecipe>()[Idx])
+          OpenACCReductionRecipe(R.AllocaDecl, NewCombiners);
+    }
   }
 
 public:
@@ -1347,13 +1380,17 @@ class OpenACCReductionClause final
   static OpenACCReductionClause *
   Create(const ASTContext &C, SourceLocation BeginLoc, SourceLocation LParenLoc,
          OpenACCReductionOperator Operator, ArrayRef<Expr *> VarList,
-         ArrayRef<OpenACCReductionRecipe> Recipes, SourceLocation EndLoc);
+         ArrayRef<OpenACCReductionRecipeWithStorage> Recipes,
+         SourceLocation EndLoc);
 
   OpenACCReductionOperator getReductionOp() const { return Op; }
 
   size_t numTrailingObjects(OverloadToken<Expr *>) const {
     return getExprs().size();
   }
+  size_t numTrailingObjects(OverloadToken<OpenACCReductionRecipe>) const {
+    return getExprs().size();
+  }
 };
 
 class OpenACCLinkClause final

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -13665,6 +13665,11 @@ def warn_acc_var_referenced_lacks_op
               "reference has no effect">,
       InGroup<DiagGroup<"openacc-var-lacks-operation">>,
       DefaultError;
+def err_acc_reduction_recipe_no_op
+    : Error<"variable of type %0 referenced in OpenACC 'reduction' clause does "
+            "not have a valid operation available">;
+def note_acc_reduction_recipe_noop_field
+    : Note<"while forming combiner for compound type %0">;
 
 // AMDGCN builtins diagnostics
 def err_amdgcn_load_lds_size_invalid_value : Error<"invalid size value">;

clang/include/clang/Sema/SemaOpenACC.h

@@ -228,6 +228,11 @@ class SemaOpenACC : public SemaBase {
 
   bool DiagnoseAllowedClauses(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
                               SourceLocation ClauseLoc);
+  bool CreateReductionCombinerRecipe(
+      SourceLocation loc, OpenACCReductionOperator ReductionOperator,
+      QualType VarTy,
+      llvm::SmallVectorImpl<OpenACCReductionRecipe::CombinerRecipe>
+          &CombinerRecipes);
 
 public:
   // Needed from the visitor, so should be public.
@@ -240,7 +245,7 @@ class SemaOpenACC : public SemaBase {
 
   OpenACCPrivateRecipe CreatePrivateInitRecipe(const Expr *VarExpr);
   OpenACCFirstPrivateRecipe CreateFirstPrivateInitRecipe(const Expr *VarExpr);
-  OpenACCReductionRecipe
+  OpenACCReductionRecipeWithStorage
   CreateReductionInitRecipe(OpenACCReductionOperator ReductionOperator,
                             const Expr *VarExpr);
 
@@ -946,12 +951,14 @@ class SemaOpenACC : public SemaBase {
                   ArrayRef<Expr *> IntExprs, SourceLocation EndLoc);
   // Does the checking for a 'reduction ' clause that needs to be done in
   // dependent and not dependent cases.
-  OpenACCClause *CheckReductionClause(
-      ArrayRef<const OpenACCClause *> ExistingClauses,
-      OpenACCDirectiveKind DirectiveKind, SourceLocation BeginLoc,
-      SourceLocation LParenLoc, OpenACCReductionOperator ReductionOp,
-      ArrayRef<Expr *> Vars, ArrayRef<OpenACCReductionRecipe> Recipes,
-      SourceLocation EndLoc);
+  OpenACCClause *
+  CheckReductionClause(ArrayRef<const OpenACCClause *> ExistingClauses,
+                       OpenACCDirectiveKind DirectiveKind,
+                       SourceLocation BeginLoc, SourceLocation LParenLoc,
+                       OpenACCReductionOperator ReductionOp,
+                       ArrayRef<Expr *> Vars,
+                       ArrayRef<OpenACCReductionRecipeWithStorage> Recipes,
+                       SourceLocation EndLoc);
 
   ExprResult BuildOpenACCAsteriskSizeExpr(SourceLocation AsteriskLoc);
   ExprResult ActOnOpenACCAsteriskSizeExpr(SourceLocation AsteriskLoc);

clang/lib/AST/OpenACCClause.cpp

@@ -506,11 +506,17 @@ OpenACCDeviceTypeClause *OpenACCDeviceTypeClause::Create(
 OpenACCReductionClause *OpenACCReductionClause::Create(
     const ASTContext &C, SourceLocation BeginLoc, SourceLocation LParenLoc,
     OpenACCReductionOperator Operator, ArrayRef<Expr *> VarList,
-    ArrayRef<OpenACCReductionRecipe> Recipes,
+    ArrayRef<OpenACCReductionRecipeWithStorage> Recipes,
     SourceLocation EndLoc) {
-  void *Mem = C.Allocate(
-      OpenACCReductionClause::totalSizeToAlloc<Expr *, OpenACCReductionRecipe>(
-          VarList.size(), Recipes.size()));
+  size_t NumCombiners = llvm::accumulate(
+      Recipes, 0, [](size_t Num, const OpenACCReductionRecipe &R) {
+        return Num + R.CombinerRecipes.size();
+      });
+
+  void *Mem = C.Allocate(OpenACCReductionClause::totalSizeToAlloc<
+                         Expr *, OpenACCReductionRecipe,
+                         OpenACCReductionRecipe::CombinerRecipe>(
+      VarList.size(), Recipes.size(), NumCombiners));
   return new (Mem) OpenACCReductionClause(BeginLoc, LParenLoc, Operator,
                                           VarList, Recipes, EndLoc);
 }

clang/lib/Sema/SemaOpenACC.cpp

@@ -2883,12 +2883,12 @@ SemaOpenACC::CreateFirstPrivateInitRecipe(const Expr *VarExpr) {
   return OpenACCFirstPrivateRecipe(AllocaDecl, Temporary);
 }
 
-OpenACCReductionRecipe SemaOpenACC::CreateReductionInitRecipe(
+OpenACCReductionRecipeWithStorage SemaOpenACC::CreateReductionInitRecipe(
     OpenACCReductionOperator ReductionOperator, const Expr *VarExpr) {
   // We don't strip bounds here, so that we are doing our recipe init at the
   // 'lowest' possible level.  Codegen is going to have to do its own 'looping'.
   if (!VarExpr || VarExpr->getType()->isDependentType())
-    return OpenACCReductionRecipe::Empty();
+    return OpenACCReductionRecipeWithStorage::Empty();
 
   QualType VarTy =
       VarExpr->getType().getNonReferenceType().getUnqualifiedType();
@@ -2898,6 +2898,15 @@ OpenACCReductionRecipe SemaOpenACC::CreateReductionInitRecipe(
           dyn_cast<ArraySectionExpr>(VarExpr->IgnoreParenImpCasts()))
     VarTy = ASE->getElementType();
 
+  llvm::SmallVector<OpenACCReductionRecipe::CombinerRecipe, 1> CombinerRecipes;
+
+  // We use the 'set-ness' of the alloca-decl to determine whether the combiner
+  // is 'set' or not, so we can skip any attempts at it if we're going to fail
+  // at any of the combiners.
+  if (CreateReductionCombinerRecipe(VarExpr->getBeginLoc(), ReductionOperator,
+                                    VarTy, CombinerRecipes))
+    return OpenACCReductionRecipeWithStorage::Empty();
+
   VarDecl *AllocaDecl = CreateAllocaDecl(
       getASTContext(), SemaRef.getCurContext(), VarExpr->getBeginLoc(),
       &getASTContext().Idents.get("openacc.reduction.init"), VarTy);
@@ -2946,5 +2955,163 @@ OpenACCReductionRecipe SemaOpenACC::CreateReductionInitRecipe(
     AllocaDecl->setInit(Init.get());
     AllocaDecl->setInitStyle(VarDecl::CallInit);
   }
-  return OpenACCReductionRecipe(AllocaDecl, {});
+
+  return OpenACCReductionRecipeWithStorage(AllocaDecl, CombinerRecipes);
+}
+
+bool SemaOpenACC::CreateReductionCombinerRecipe(
+    SourceLocation Loc, OpenACCReductionOperator ReductionOperator,
+    QualType VarTy,
+    llvm::SmallVectorImpl<OpenACCReductionRecipe::CombinerRecipe>
+        &CombinerRecipes) {
+  // Now we can try to generate the 'combiner' recipe. This is a little
+  // complicated in that if the 'VarTy' is an array type, we want to take its
+  // element type so we can generate that.  Additionally, if this is a struct,
+  // we have two options: If there is overloaded operators, we want to take
+  // THOSE, else we want to do the individual elements.
+
+  BinaryOperatorKind BinOp;
+  switch (ReductionOperator) {
+  case OpenACCReductionOperator::Invalid:
+    // This can only happen when there is an error, and since these inits
+    // are used for code generation, we can just ignore/not bother doing any
+    // initialization here.
+    CombinerRecipes.push_back({nullptr, nullptr, nullptr});
+    return false;
+  case OpenACCReductionOperator::Addition:
+    BinOp = BinaryOperatorKind::BO_AddAssign;
+    break;
+  case OpenACCReductionOperator::Multiplication:
+    BinOp = BinaryOperatorKind::BO_MulAssign;
+    break;
+  case OpenACCReductionOperator::BitwiseAnd:
+    BinOp = BinaryOperatorKind::BO_AndAssign;
+    break;
+  case OpenACCReductionOperator::BitwiseOr:
+    BinOp = BinaryOperatorKind::BO_OrAssign;
+    break;
+  case OpenACCReductionOperator::BitwiseXOr:
+    BinOp = BinaryOperatorKind::BO_XorAssign;
+    break;
+
+  case OpenACCReductionOperator::Max:
+  case OpenACCReductionOperator::Min:
+  case OpenACCReductionOperator::And:
+  case OpenACCReductionOperator::Or:
+    // We just want a 'NYI' error in the backend, so leave an empty combiner
+    // recipe, and claim success.
+    CombinerRecipes.push_back({nullptr, nullptr, nullptr});
+    return false;
+  }
+
+  // If VarTy is an array type, at the top level only, we want to do our
+  // compares/decomp/etc at the element level.
+  if (auto *AT = getASTContext().getAsArrayType(VarTy))
+    VarTy = AT->getElementType();
+
+  assert(!VarTy->isArrayType() && "Only 1 level of array allowed");
+
+  auto tryCombiner = [&, this](DeclRefExpr *LHSDRE, DeclRefExpr *RHSDRE,
+                               bool IncludeTrap) {
+    // TODO: OpenACC: we have to figure out based on the bin-op how to do the
+    // ones that we can't just use compound operators for.  So &&, ||, max, and
+    // min aren't really clear what we could do here.
+    if (IncludeTrap) {
+      // Trap all of the errors here, we'll emit our own at the end.
+      Sema::TentativeAnalysisScope Trap{SemaRef};
+
+      return SemaRef.BuildBinOp(SemaRef.getCurScope(), Loc, BinOp, LHSDRE,
+                                RHSDRE,
+                                /*ForFoldExpr=*/false);
+    } else {
+      return SemaRef.BuildBinOp(SemaRef.getCurScope(), Loc, BinOp, LHSDRE,
+                                RHSDRE,
+                                /*ForFoldExpr=*/false);
+    }
+  };
+
+  struct CombinerAttemptTy {
+    VarDecl *LHS;
+    DeclRefExpr *LHSDRE;
+    VarDecl *RHS;
+    DeclRefExpr *RHSDRE;
+    Expr *Op;
+  };
+
+  auto formCombiner = [&, this](QualType Ty) -> CombinerAttemptTy {
+    VarDecl *LHSDecl = CreateAllocaDecl(
+        getASTContext(), SemaRef.getCurContext(), Loc,
+        &getASTContext().Idents.get("openacc.reduction.combiner.lhs"), Ty);
+    auto *LHSDRE = DeclRefExpr::Create(
+        getASTContext(), NestedNameSpecifierLoc{}, SourceLocation{}, LHSDecl,
+        /*ReferstoEnclosingVariableOrCapture=*/false,
+        DeclarationNameInfo{DeclarationName{LHSDecl->getDeclName()},
+                            LHSDecl->getBeginLoc()},
+        Ty, clang::VK_LValue, LHSDecl, nullptr, NOUR_None);
+    VarDecl *RHSDecl = CreateAllocaDecl(
+        getASTContext(), SemaRef.getCurContext(), Loc,
+        &getASTContext().Idents.get("openacc.reduction.combiner.lhs"), Ty);
+    auto *RHSDRE = DeclRefExpr::Create(
+        getASTContext(), NestedNameSpecifierLoc{}, SourceLocation{}, RHSDecl,
+        /*ReferstoEnclosingVariableOrCapture=*/false,
+        DeclarationNameInfo{DeclarationName{RHSDecl->getDeclName()},
+                            RHSDecl->getBeginLoc()},
+        Ty, clang::VK_LValue, RHSDecl, nullptr, NOUR_None);
+
+    ExprResult BinOpResult = tryCombiner(LHSDRE, RHSDRE, /*IncludeTrap=*/true);
+
+    return {LHSDecl, LHSDRE, RHSDecl, RHSDRE, BinOpResult.get()};
+  };
+
+  CombinerAttemptTy TopLevelCombinerInfo = formCombiner(VarTy);
+
+  if (TopLevelCombinerInfo.Op) {
+    if (!TopLevelCombinerInfo.Op->containsErrors() &&
+        TopLevelCombinerInfo.Op->isInstantiationDependent()) {
+      // If this is instantiation dependent, we're just going to 'give up' here
+      // and count on us to get it right during instantaition.
+      CombinerRecipes.push_back({nullptr, nullptr, nullptr});
+      return false;
+    } else if (!TopLevelCombinerInfo.Op->containsErrors()) {
+      // Else, we succeeded, we can just return this combiner.
+      CombinerRecipes.push_back({TopLevelCombinerInfo.LHS,
+                                 TopLevelCombinerInfo.RHS,
+                                 TopLevelCombinerInfo.Op});
+      return false;
+    }
+  }
+
+  // Since the 'root' level didn't fail, the only thing that could be successful
+  // is a struct that we decompose on its individual fields.
+
+  RecordDecl *RD = VarTy->getAsRecordDecl();
+  if (!RD) {
+    Diag(Loc, diag::err_acc_reduction_recipe_no_op) << VarTy;
+    tryCombiner(TopLevelCombinerInfo.LHSDRE, TopLevelCombinerInfo.RHSDRE,
+                /*IncludeTrap=*/false);
+    return true;
+  }
+
+  for (const FieldDecl *FD : RD->fields()) {
+    CombinerAttemptTy FieldCombinerInfo = formCombiner(FD->getType());
+
+    if (!FieldCombinerInfo.Op || FieldCombinerInfo.Op->containsErrors()) {
+      Diag(Loc, diag::err_acc_reduction_recipe_no_op) << FD->getType();
+      Diag(FD->getBeginLoc(), diag::note_acc_reduction_recipe_noop_field) << RD;
+      tryCombiner(FieldCombinerInfo.LHSDRE, FieldCombinerInfo.RHSDRE,
+                  /*IncludeTrap=*/false);
+      return true;
+    }
+
+    if (FieldCombinerInfo.Op->isInstantiationDependent()) {
+      // If this is instantiation dependent, we're just going to 'give up' here
+      // and count on us to get it right during instantaition.
+      CombinerRecipes.push_back({nullptr, nullptr, nullptr});
+    } else {
+      CombinerRecipes.push_back(
+          {FieldCombinerInfo.LHS, FieldCombinerInfo.RHS, FieldCombinerInfo.Op});
+    }
+  }
+
+  return false;
 }

clang/lib/Sema/SemaOpenACCClause.cpp

@@ -1772,7 +1772,7 @@ OpenACCClause *SemaOpenACCClauseVisitor::VisitReductionClause(
   }
 
   SmallVector<Expr *> ValidVars;
-  SmallVector<OpenACCReductionRecipe> Recipes;
+  SmallVector<OpenACCReductionRecipeWithStorage> Recipes;
 
   for (Expr *Var : Clause.getVarList()) {
     ExprResult Res = SemaRef.CheckReductionVar(Clause.getDirectiveKind(),
@@ -2196,7 +2196,7 @@ OpenACCClause *SemaOpenACC::CheckReductionClause(
     ArrayRef<const OpenACCClause *> ExistingClauses,
     OpenACCDirectiveKind DirectiveKind, SourceLocation BeginLoc,
     SourceLocation LParenLoc, OpenACCReductionOperator ReductionOp,
-    ArrayRef<Expr *> Vars, ArrayRef<OpenACCReductionRecipe> Recipes,
+    ArrayRef<Expr *> Vars, ArrayRef<OpenACCReductionRecipeWithStorage> Recipes,
     SourceLocation EndLoc) {
   if (DirectiveKind == OpenACCDirectiveKind::Loop ||
       isOpenACCCombinedDirectiveKind(DirectiveKind)) {