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

This reverts commit 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.

Author: erichkeane

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.

clang/lib/Sema/SemaOpenACC.cpp

@@ -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 OpenACCReductionRecipe::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 OpenACCReductionRecipe(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;
 }