//===--- SemaOpenACC.cpp - Semantic Analysis for OpenACC constructs -------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements semantic analysis for OpenACC constructs, and things
/// that are not clause specific.
///
//===----------------------------------------------------------------------===//

#include "clang/Sema/SemaOpenACC.h"
#include "clang/AST/DeclOpenACC.h"
#include "clang/AST/StmtOpenACC.h"
#include "clang/Basic/DiagnosticSema.h"
#include "clang/Basic/OpenACCKinds.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/Sema.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Casting.h"

using namespace clang;

namespace {
bool diagnoseConstructAppertainment(SemaOpenACC &S, OpenACCDirectiveKind K,
                                    SourceLocation StartLoc, bool IsStmt) {
  switch (K) {
  default:
  case OpenACCDirectiveKind::Invalid:
    // Nothing to do here, both invalid and unimplemented don't really need to
    // do anything.
    break;
  case OpenACCDirectiveKind::Parallel:
  case OpenACCDirectiveKind::ParallelLoop:
  case OpenACCDirectiveKind::Serial:
  case OpenACCDirectiveKind::SerialLoop:
  case OpenACCDirectiveKind::Kernels:
  case OpenACCDirectiveKind::KernelsLoop:
  case OpenACCDirectiveKind::Loop:
  case OpenACCDirectiveKind::Data:
  case OpenACCDirectiveKind::EnterData:
  case OpenACCDirectiveKind::ExitData:
  case OpenACCDirectiveKind::HostData:
  case OpenACCDirectiveKind::Wait:
  case OpenACCDirectiveKind::Update:
  case OpenACCDirectiveKind::Init:
  case OpenACCDirectiveKind::Shutdown:
  case OpenACCDirectiveKind::Cache:
  case OpenACCDirectiveKind::Atomic:
    if (!IsStmt)
      return S.Diag(StartLoc, diag::err_acc_construct_appertainment) << K;
    break;
  }
  return false;
}

void CollectActiveReductionClauses(
    llvm::SmallVector<OpenACCReductionClause *> &ActiveClauses,
    ArrayRef<OpenACCClause *> CurClauses) {
  for (auto *CurClause : CurClauses) {
    if (auto *RedClause = dyn_cast<OpenACCReductionClause>(CurClause);
        RedClause && !RedClause->getVarList().empty())
      ActiveClauses.push_back(RedClause);
  }
}

// Depth needs to be preserved for all associated statements that aren't
// supposed to modify the compute/combined/loop construct information.
bool PreserveLoopRAIIDepthInAssociatedStmtRAII(OpenACCDirectiveKind DK) {
  switch (DK) {
  case OpenACCDirectiveKind::Parallel:
  case OpenACCDirectiveKind::ParallelLoop:
  case OpenACCDirectiveKind::Serial:
  case OpenACCDirectiveKind::SerialLoop:
  case OpenACCDirectiveKind::Kernels:
  case OpenACCDirectiveKind::KernelsLoop:
  case OpenACCDirectiveKind::Loop:
    return false;
  case OpenACCDirectiveKind::Data:
  case OpenACCDirectiveKind::HostData:
  case OpenACCDirectiveKind::Atomic:
    return true;
  case OpenACCDirectiveKind::Cache:
  case OpenACCDirectiveKind::Routine:
  case OpenACCDirectiveKind::Declare:
  case OpenACCDirectiveKind::EnterData:
  case OpenACCDirectiveKind::ExitData:
  case OpenACCDirectiveKind::Wait:
  case OpenACCDirectiveKind::Init:
  case OpenACCDirectiveKind::Shutdown:
  case OpenACCDirectiveKind::Set:
  case OpenACCDirectiveKind::Update:
    llvm_unreachable("Doesn't have an associated stmt");
  case OpenACCDirectiveKind::Invalid:
    llvm_unreachable("Unhandled directive kind?");
  }
  llvm_unreachable("Unhandled directive kind?");
}

} // namespace

SemaOpenACC::SemaOpenACC(Sema &S) : SemaBase(S) {}

SemaOpenACC::AssociatedStmtRAII::AssociatedStmtRAII(
    SemaOpenACC &S, OpenACCDirectiveKind DK, SourceLocation DirLoc,
    ArrayRef<const OpenACCClause *> UnInstClauses,
    ArrayRef<OpenACCClause *> Clauses)
    : SemaRef(S), OldActiveComputeConstructInfo(S.ActiveComputeConstructInfo),
      DirKind(DK), OldLoopGangClauseOnKernel(S.LoopGangClauseOnKernel),
      OldLoopWorkerClauseLoc(S.LoopWorkerClauseLoc),
      OldLoopVectorClauseLoc(S.LoopVectorClauseLoc),
      OldLoopWithoutSeqInfo(S.LoopWithoutSeqInfo),
      ActiveReductionClauses(S.ActiveReductionClauses),
      LoopRAII(SemaRef, PreserveLoopRAIIDepthInAssociatedStmtRAII(DirKind)) {

  // Compute constructs end up taking their 'loop'.
  if (DirKind == OpenACCDirectiveKind::Parallel ||
      DirKind == OpenACCDirectiveKind::Serial ||
      DirKind == OpenACCDirectiveKind::Kernels) {
    CollectActiveReductionClauses(S.ActiveReductionClauses, Clauses);
    SemaRef.ActiveComputeConstructInfo.Kind = DirKind;
    SemaRef.ActiveComputeConstructInfo.Clauses = Clauses;

    // OpenACC 3.3 2.9.2: When the parent compute construct is a kernels
    // construct, the gang clause behaves as follows. ... The region of a loop
    // with a gang clause may not contain another loop with a gang clause unless
    // within a nested compute region.
    //
    // Implement the 'unless within a nested compute region' part.
    SemaRef.LoopGangClauseOnKernel = {};
    SemaRef.LoopWorkerClauseLoc = {};
    SemaRef.LoopVectorClauseLoc = {};
    SemaRef.LoopWithoutSeqInfo = {};
  } else if (DirKind == OpenACCDirectiveKind::ParallelLoop ||
             DirKind == OpenACCDirectiveKind::SerialLoop ||
             DirKind == OpenACCDirectiveKind::KernelsLoop) {
    SemaRef.ActiveComputeConstructInfo.Kind = DirKind;
    SemaRef.ActiveComputeConstructInfo.Clauses = Clauses;

    CollectActiveReductionClauses(S.ActiveReductionClauses, Clauses);
    SetCollapseInfoBeforeAssociatedStmt(UnInstClauses, Clauses);
    SetTileInfoBeforeAssociatedStmt(UnInstClauses, Clauses);

    SemaRef.LoopGangClauseOnKernel = {};
    SemaRef.LoopWorkerClauseLoc = {};
    SemaRef.LoopVectorClauseLoc = {};

    // Set the active 'loop' location if there isn't a 'seq' on it, so we can
    // diagnose the for loops.
    SemaRef.LoopWithoutSeqInfo = {};
    if (Clauses.end() ==
        llvm::find_if(Clauses, llvm::IsaPred<OpenACCSeqClause>))
      SemaRef.LoopWithoutSeqInfo = {DirKind, DirLoc};

    // OpenACC 3.3 2.9.2: When the parent compute construct is a kernels
    // construct, the gang clause behaves as follows. ... The region of a loop
    // with a gang clause may not contain another loop with a gang clause unless
    // within a nested compute region.
    //
    // We don't bother doing this when this is a template instantiation, as
    // there is no reason to do these checks: the existance of a
    // gang/kernels/etc cannot be dependent.
    if (DirKind == OpenACCDirectiveKind::KernelsLoop && UnInstClauses.empty()) {
      // This handles the 'outer loop' part of this.
      auto *Itr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCGangClause>);
      if (Itr != Clauses.end())
        SemaRef.LoopGangClauseOnKernel = {(*Itr)->getBeginLoc(), DirKind};
    }

    if (UnInstClauses.empty()) {
      auto *Itr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCWorkerClause>);
      if (Itr != Clauses.end())
        SemaRef.LoopWorkerClauseLoc = (*Itr)->getBeginLoc();

      auto *Itr2 = llvm::find_if(Clauses, llvm::IsaPred<OpenACCVectorClause>);
      if (Itr2 != Clauses.end())
        SemaRef.LoopVectorClauseLoc = (*Itr2)->getBeginLoc();
    }
  } else if (DirKind == OpenACCDirectiveKind::Loop) {
    CollectActiveReductionClauses(S.ActiveReductionClauses, Clauses);
    SetCollapseInfoBeforeAssociatedStmt(UnInstClauses, Clauses);
    SetTileInfoBeforeAssociatedStmt(UnInstClauses, Clauses);

    // Set the active 'loop' location if there isn't a 'seq' on it, so we can
    // diagnose the for loops.
    SemaRef.LoopWithoutSeqInfo = {};
    if (Clauses.end() ==
        llvm::find_if(Clauses, llvm::IsaPred<OpenACCSeqClause>))
      SemaRef.LoopWithoutSeqInfo = {DirKind, DirLoc};

    // OpenACC 3.3 2.9.2: When the parent compute construct is a kernels
    // construct, the gang clause behaves as follows. ... The region of a loop
    // with a gang clause may not contain another loop with a gang clause unless
    // within a nested compute region.
    //
    // We don't bother doing this when this is a template instantiation, as
    // there is no reason to do these checks: the existance of a
    // gang/kernels/etc cannot be dependent.
    if (SemaRef.getActiveComputeConstructInfo().Kind ==
            OpenACCDirectiveKind::Kernels &&
        UnInstClauses.empty()) {
      // This handles the 'outer loop' part of this.
      auto *Itr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCGangClause>);
      if (Itr != Clauses.end())
        SemaRef.LoopGangClauseOnKernel = {(*Itr)->getBeginLoc(),
                                          OpenACCDirectiveKind::Kernels};
    }

    if (UnInstClauses.empty()) {
      auto *Itr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCWorkerClause>);
      if (Itr != Clauses.end())
        SemaRef.LoopWorkerClauseLoc = (*Itr)->getBeginLoc();

      auto *Itr2 = llvm::find_if(Clauses, llvm::IsaPred<OpenACCVectorClause>);
      if (Itr2 != Clauses.end())
        SemaRef.LoopVectorClauseLoc = (*Itr2)->getBeginLoc();
    }
  }
}

namespace {
// Given two collapse clauses, and the uninstanted version of the new one,
// return the 'best' one for the purposes of setting the collapse checking
// values.
const OpenACCCollapseClause *
getBestCollapseCandidate(const OpenACCCollapseClause *Old,
                         const OpenACCCollapseClause *New,
                         const OpenACCCollapseClause *UnInstNew) {
  // If the loop count is nullptr, it is because instantiation failed, so this
  // can't be the best one.
  if (!New->getLoopCount())
    return Old;

  // If the loop-count had an error, than 'new' isn't a candidate.
  if (!New->getLoopCount())
    return Old;

  // Don't consider uninstantiated ones, since we can't really check these.
  if (New->getLoopCount()->isInstantiationDependent())
    return Old;

  // If this is an instantiation, and the old version wasn't instantation
  // dependent, than nothing has changed and we've already done a diagnostic
  // based on this one, so don't consider it.
  if (UnInstNew && !UnInstNew->getLoopCount()->isInstantiationDependent())
    return Old;

  // New is now a valid candidate, so if there isn't an old one at this point,
  // New is the only valid one.
  if (!Old)
    return New;

  // If the 'New' expression has a larger value than 'Old', then it is the new
  // best candidate.
  if (cast<ConstantExpr>(Old->getLoopCount())->getResultAsAPSInt() <
      cast<ConstantExpr>(New->getLoopCount())->getResultAsAPSInt())
    return New;

  return Old;
}
} // namespace

void SemaOpenACC::AssociatedStmtRAII::SetCollapseInfoBeforeAssociatedStmt(
    ArrayRef<const OpenACCClause *> UnInstClauses,
    ArrayRef<OpenACCClause *> Clauses) {

  // Reset this checking for loops that aren't covered in a RAII object.
  SemaRef.LoopInfo.CurLevelHasLoopAlready = false;
  SemaRef.CollapseInfo.CollapseDepthSatisfied = true;
  SemaRef.CollapseInfo.CurCollapseCount = 0;
  SemaRef.TileInfo.TileDepthSatisfied = true;

  // We make sure to take an optional list of uninstantiated clauses, so that
  // we can check to make sure we don't 'double diagnose' in the event that
  // the value of 'N' was not dependent in a template. Since we cannot count on
  // there only being a single collapse clause, we count on the order to make
  // sure get the matching ones, and we count on TreeTransform not removing
  // these, even if loop-count instantiation failed. We can check the
  // non-dependent ones right away, and realize that subsequent instantiation
  // can only make it more specific.

  auto *UnInstClauseItr =
      llvm::find_if(UnInstClauses, llvm::IsaPred<OpenACCCollapseClause>);
  auto *ClauseItr =
      llvm::find_if(Clauses, llvm::IsaPred<OpenACCCollapseClause>);
  const OpenACCCollapseClause *FoundClause = nullptr;

  // Loop through the list of Collapse clauses and find the one that:
  // 1- Has a non-dependent, non-null loop count (null means error, likely
  // during instantiation).
  // 2- If UnInstClauses isn't empty, its corresponding
  // loop count was dependent.
  // 3- Has the largest 'loop count' of all.
  while (ClauseItr != Clauses.end()) {
    const OpenACCCollapseClause *CurClause =
        cast<OpenACCCollapseClause>(*ClauseItr);
    const OpenACCCollapseClause *UnInstCurClause =
        UnInstClauseItr == UnInstClauses.end()
            ? nullptr
            : cast<OpenACCCollapseClause>(*UnInstClauseItr);

    FoundClause =
        getBestCollapseCandidate(FoundClause, CurClause, UnInstCurClause);

    UnInstClauseItr =
        UnInstClauseItr == UnInstClauses.end()
            ? UnInstClauseItr
            : std::find_if(std::next(UnInstClauseItr), UnInstClauses.end(),
                           llvm::IsaPred<OpenACCCollapseClause>);
    ClauseItr = std::find_if(std::next(ClauseItr), Clauses.end(),
                             llvm::IsaPred<OpenACCCollapseClause>);
  }

  if (!FoundClause)
    return;

  SemaRef.CollapseInfo.ActiveCollapse = FoundClause;
  SemaRef.CollapseInfo.CollapseDepthSatisfied = false;
  SemaRef.CollapseInfo.CurCollapseCount =
      cast<ConstantExpr>(FoundClause->getLoopCount())->getResultAsAPSInt();
  SemaRef.CollapseInfo.DirectiveKind = DirKind;
}

void SemaOpenACC::AssociatedStmtRAII::SetTileInfoBeforeAssociatedStmt(
    ArrayRef<const OpenACCClause *> UnInstClauses,
    ArrayRef<OpenACCClause *> Clauses) {
  // We don't diagnose if this is during instantiation, since the only thing we
  // care about is the number of arguments, which we can figure out without
  // instantiation, so we don't want to double-diagnose.
  if (UnInstClauses.size() > 0)
    return;
  auto *TileClauseItr =
      llvm::find_if(Clauses, llvm::IsaPred<OpenACCTileClause>);

  if (Clauses.end() == TileClauseItr)
    return;

  OpenACCTileClause *TileClause = cast<OpenACCTileClause>(*TileClauseItr);

  // Multiple tile clauses are allowed, so ensure that we use the one with the
  // largest 'tile count'.
  while (Clauses.end() !=
         (TileClauseItr = std::find_if(std::next(TileClauseItr), Clauses.end(),
                                       llvm::IsaPred<OpenACCTileClause>))) {
    OpenACCTileClause *NewClause = cast<OpenACCTileClause>(*TileClauseItr);
    if (NewClause->getSizeExprs().size() > TileClause->getSizeExprs().size())
      TileClause = NewClause;
  }

  SemaRef.TileInfo.ActiveTile = TileClause;
  SemaRef.TileInfo.TileDepthSatisfied = false;
  SemaRef.TileInfo.CurTileCount =
      static_cast<unsigned>(TileClause->getSizeExprs().size());
  SemaRef.TileInfo.DirectiveKind = DirKind;
}

SemaOpenACC::AssociatedStmtRAII::~AssociatedStmtRAII() {
  if (DirKind == OpenACCDirectiveKind::Parallel ||
      DirKind == OpenACCDirectiveKind::Serial ||
      DirKind == OpenACCDirectiveKind::Kernels ||
      DirKind == OpenACCDirectiveKind::Loop ||
      DirKind == OpenACCDirectiveKind::ParallelLoop ||
      DirKind == OpenACCDirectiveKind::SerialLoop ||
      DirKind == OpenACCDirectiveKind::KernelsLoop) {
    SemaRef.ActiveComputeConstructInfo = OldActiveComputeConstructInfo;
    SemaRef.LoopGangClauseOnKernel = OldLoopGangClauseOnKernel;
    SemaRef.LoopWorkerClauseLoc = OldLoopWorkerClauseLoc;
    SemaRef.LoopVectorClauseLoc = OldLoopVectorClauseLoc;
    SemaRef.LoopWithoutSeqInfo = OldLoopWithoutSeqInfo;
    SemaRef.ActiveReductionClauses.swap(ActiveReductionClauses);
  } else if (DirKind == OpenACCDirectiveKind::Data ||
             DirKind == OpenACCDirectiveKind::HostData) {
    // Intentionally doesn't reset the Loop, Compute Construct, or reduction
    // effects.
  }
}

void SemaOpenACC::ActOnConstruct(OpenACCDirectiveKind K,
                                 SourceLocation DirLoc) {
  // Start an evaluation context to parse the clause arguments on.
  SemaRef.PushExpressionEvaluationContext(
      Sema::ExpressionEvaluationContext::PotentiallyEvaluated);

  // There is nothing do do here as all we have at this point is the name of the
  // construct itself.
}

ExprResult SemaOpenACC::ActOnIntExpr(OpenACCDirectiveKind DK,
                                     OpenACCClauseKind CK, SourceLocation Loc,
                                     Expr *IntExpr) {

  assert(((DK != OpenACCDirectiveKind::Invalid &&
           CK == OpenACCClauseKind::Invalid) ||
          (DK == OpenACCDirectiveKind::Invalid &&
           CK != OpenACCClauseKind::Invalid) ||
          (DK == OpenACCDirectiveKind::Invalid &&
           CK == OpenACCClauseKind::Invalid)) &&
         "Only one of directive or clause kind should be provided");

  class IntExprConverter : public Sema::ICEConvertDiagnoser {
    OpenACCDirectiveKind DirectiveKind;
    OpenACCClauseKind ClauseKind;
    Expr *IntExpr;

    // gets the index into the diagnostics so we can use this for clauses,
    // directives, and sub array.s
    unsigned getDiagKind() const {
      if (ClauseKind != OpenACCClauseKind::Invalid)
        return 0;
      if (DirectiveKind != OpenACCDirectiveKind::Invalid)
        return 1;
      return 2;
    }

  public:
    IntExprConverter(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
                     Expr *IntExpr)
        : ICEConvertDiagnoser(/*AllowScopedEnumerations=*/false,
                              /*Suppress=*/false,
                              /*SuppressConversion=*/true),
          DirectiveKind(DK), ClauseKind(CK), IntExpr(IntExpr) {}

    bool match(QualType T) override {
      // OpenACC spec just calls this 'integer expression' as having an
      // 'integer type', so fall back on C99's 'integer type'.
      return T->isIntegerType();
    }
    SemaBase::SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
                                                   QualType T) override {
      return S.Diag(Loc, diag::err_acc_int_expr_requires_integer)
             << getDiagKind() << ClauseKind << DirectiveKind << T;
    }

    SemaBase::SemaDiagnosticBuilder
    diagnoseIncomplete(Sema &S, SourceLocation Loc, QualType T) override {
      return S.Diag(Loc, diag::err_acc_int_expr_incomplete_class_type)
             << T << IntExpr->getSourceRange();
    }

    SemaBase::SemaDiagnosticBuilder
    diagnoseExplicitConv(Sema &S, SourceLocation Loc, QualType T,
                         QualType ConvTy) override {
      return S.Diag(Loc, diag::err_acc_int_expr_explicit_conversion)
             << T << ConvTy;
    }

    SemaBase::SemaDiagnosticBuilder noteExplicitConv(Sema &S,
                                                     CXXConversionDecl *Conv,
                                                     QualType ConvTy) override {
      return S.Diag(Conv->getLocation(), diag::note_acc_int_expr_conversion)
             << ConvTy->isEnumeralType() << ConvTy;
    }

    SemaBase::SemaDiagnosticBuilder
    diagnoseAmbiguous(Sema &S, SourceLocation Loc, QualType T) override {
      return S.Diag(Loc, diag::err_acc_int_expr_multiple_conversions) << T;
    }

    SemaBase::SemaDiagnosticBuilder
    noteAmbiguous(Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
      return S.Diag(Conv->getLocation(), diag::note_acc_int_expr_conversion)
             << ConvTy->isEnumeralType() << ConvTy;
    }

    SemaBase::SemaDiagnosticBuilder
    diagnoseConversion(Sema &S, SourceLocation Loc, QualType T,
                       QualType ConvTy) override {
      llvm_unreachable("conversion functions are permitted");
    }
  } IntExprDiagnoser(DK, CK, IntExpr);

  if (!IntExpr)
    return ExprError();

  ExprResult IntExprResult = SemaRef.PerformContextualImplicitConversion(
      Loc, IntExpr, IntExprDiagnoser);
  if (IntExprResult.isInvalid())
    return ExprError();

  IntExpr = IntExprResult.get();
  if (!IntExpr->isTypeDependent() && !IntExpr->getType()->isIntegerType())
    return ExprError();

  // TODO OpenACC: Do we want to perform usual unary conversions here? When
  // doing codegen we might find that is necessary, but skip it for now.
  return IntExpr;
}

bool SemaOpenACC::CheckVarIsPointerType(OpenACCClauseKind ClauseKind,
                                        Expr *VarExpr) {
  // We already know that VarExpr is a proper reference to a variable, so we
  // should be able to just take the type of the expression to get the type of
  // the referenced variable.

  // We've already seen an error, don't diagnose anything else.
  if (!VarExpr || VarExpr->containsErrors())
    return false;

  if (isa<ArraySectionExpr>(VarExpr->IgnoreParenImpCasts()) ||
      VarExpr->hasPlaceholderType(BuiltinType::ArraySection)) {
    Diag(VarExpr->getExprLoc(), diag::err_array_section_use) << /*OpenACC=*/0;
    Diag(VarExpr->getExprLoc(), diag::note_acc_expected_pointer_var);
    return true;
  }

  QualType Ty = VarExpr->getType();
  Ty = Ty.getNonReferenceType().getUnqualifiedType();

  // Nothing we can do if this is a dependent type.
  if (Ty->isDependentType())
    return false;

  if (!Ty->isPointerType())
    return Diag(VarExpr->getExprLoc(), diag::err_acc_var_not_pointer_type)
           << ClauseKind << Ty;
  return false;
}

void SemaOpenACC::ActOnStartParseVar(OpenACCDirectiveKind DK,
                                     OpenACCClauseKind CK) {
  if (DK == OpenACCDirectiveKind::Cache) {
    CacheInfo.ParsingCacheVarList = true;
    CacheInfo.IsInvalidCacheRef = false;
  }
}

void SemaOpenACC::ActOnInvalidParseVar() {
  CacheInfo.ParsingCacheVarList = false;
  CacheInfo.IsInvalidCacheRef = false;
}

ExprResult SemaOpenACC::ActOnCacheVar(Expr *VarExpr) {
  Expr *CurVarExpr = VarExpr->IgnoreParenImpCasts();
  // Clear this here, so we can do the returns based on the invalid cache ref
  // here.  Note all return statements in this function must return ExprError if
  // IsInvalidCacheRef. However, instead of doing an 'early return' in that
  // case, we can let the rest of the diagnostics happen, as the invalid decl
  // ref is a warning.
  bool WasParsingInvalidCacheRef =
      CacheInfo.ParsingCacheVarList && CacheInfo.IsInvalidCacheRef;
  CacheInfo.ParsingCacheVarList = false;
  CacheInfo.IsInvalidCacheRef = false;

  if (!isa<ArraySectionExpr, ArraySubscriptExpr>(CurVarExpr)) {
    Diag(VarExpr->getExprLoc(), diag::err_acc_not_a_var_ref_cache);
    return ExprError();
  }

  // It isn't clear what 'simple array element or simple subarray' means, so we
  // will just allow arbitrary depth.
  while (isa<ArraySectionExpr, ArraySubscriptExpr>(CurVarExpr)) {
    if (auto *SubScrpt = dyn_cast<ArraySubscriptExpr>(CurVarExpr))
      CurVarExpr = SubScrpt->getBase()->IgnoreParenImpCasts();
    else
      CurVarExpr =
          cast<ArraySectionExpr>(CurVarExpr)->getBase()->IgnoreParenImpCasts();
  }

  // References to a VarDecl are fine.
  if (const auto *DRE = dyn_cast<DeclRefExpr>(CurVarExpr)) {
    if (isa<VarDecl, NonTypeTemplateParmDecl>(
            DRE->getFoundDecl()->getCanonicalDecl()))
      return WasParsingInvalidCacheRef ? ExprEmpty() : VarExpr;
  }

  if (const auto *ME = dyn_cast<MemberExpr>(CurVarExpr)) {
    if (isa<FieldDecl>(ME->getMemberDecl()->getCanonicalDecl())) {
      return WasParsingInvalidCacheRef ? ExprEmpty() : VarExpr;
    }
  }

  // Nothing really we can do here, as these are dependent.  So just return they
  // are valid.
  if (isa<DependentScopeDeclRefExpr, CXXDependentScopeMemberExpr>(CurVarExpr))
    return WasParsingInvalidCacheRef ? ExprEmpty() : VarExpr;

  // There isn't really anything we can do in the case of a recovery expr, so
  // skip the diagnostic rather than produce a confusing diagnostic.
  if (isa<RecoveryExpr>(CurVarExpr))
    return ExprError();

  Diag(VarExpr->getExprLoc(), diag::err_acc_not_a_var_ref_cache);
  return ExprError();
}

void SemaOpenACC::CheckDeclReference(SourceLocation Loc, Expr *E, Decl *D) {
  if (!getLangOpts().OpenACC || !CacheInfo.ParsingCacheVarList || !D ||
      D->isInvalidDecl())
    return;
  // A 'cache' variable reference MUST be declared before the 'acc.loop' we
  // generate in codegen, so we have to mark it invalid here in some way.  We do
  // so in a bit of a convoluted way as there is no good way to put this into
  // the AST, so we store it in SemaOpenACC State.  We can check the Scope
  // during parsing to make sure there is a 'loop' before the decl is
  // declared(and skip during instantiation).
  // We only diagnose this as a warning, as this isn't required by the standard
  // (unless you take a VERY awkward reading of some awkward prose).

  Scope *CurScope = SemaRef.getCurScope();

  // if we are at TU level, we are either doing some EXTRA wacky, or are in a
  // template instantiation, so just give up.
  if (CurScope->getDepth() == 0)
    return;

  while (CurScope) {
    // If we run into a loop construct scope, than this is 'correct' in that the
    // declaration is outside of the loop.
    if (CurScope->isOpenACCLoopConstructScope())
      return;

    if (CurScope->isDeclScope(D)) {
      Diag(Loc, diag::warn_acc_cache_var_not_outside_loop);

      CacheInfo.IsInvalidCacheRef = true;
    }

    CurScope = CurScope->getParent();
  }
  // If we don't find the decl at all, we assume that it must be outside of the
  // loop (or we aren't in a loop!) so skip the diagnostic.
}

namespace {
// Check whether the type of the thing we are referencing is OK for things like
// private, firstprivate, and reduction, which require certain operators to be
// available.
ExprResult CheckVarType(SemaOpenACC &S, OpenACCClauseKind CK, Expr *VarExpr,
                        Expr *InnerExpr) {
  // There is nothing to do here, only these three have these sorts of
  // restrictions.
  if (CK != OpenACCClauseKind::Private &&
      CK != OpenACCClauseKind::FirstPrivate &&
      CK != OpenACCClauseKind::Reduction)
    return VarExpr;

  // We can't test this if it isn't here, or if the type isn't clear yet.
  if (!InnerExpr || InnerExpr->isTypeDependent())
    return VarExpr;

  const auto *RD = InnerExpr->getType()->getAsCXXRecordDecl();

  // if this isn't a C++ record decl, we can create/copy/destroy this thing at
  // will without problem, so this is a success.
  if (!RD)
    return VarExpr;

  // TODO: OpenACC:
  // Private must have default ctor + dtor in InnerExpr
  // FirstPrivate must have copyctor + dtor in InnerExpr
  // Reduction must have copyctor + dtor + operation in InnerExpr

  // TODO OpenACC: It isn't clear what the requirements are for default
  // constructor/copy constructor are for First private and reduction, but
  // private requires a default constructor.
  if (CK == OpenACCClauseKind::Private) {
    bool HasNonDeletedDefaultCtor =
        llvm::find_if(RD->ctors(), [](const CXXConstructorDecl *CD) {
          return CD->isDefaultConstructor() && !CD->isDeleted();
        }) != RD->ctors().end();
    if (!HasNonDeletedDefaultCtor && !RD->needsImplicitDefaultConstructor()) {
      S.Diag(InnerExpr->getBeginLoc(),
             clang::diag::warn_acc_var_referenced_lacks_op)
          << InnerExpr->getType() << CK
          << clang::diag::AccVarReferencedReason::DefCtor;
      return ExprError();
    }
  }

  // All 3 things need to make sure they have a dtor.
  bool DestructorDeleted =
      RD->getDestructor() && RD->getDestructor()->isDeleted();
  if (DestructorDeleted && !RD->needsImplicitDestructor()) {
    S.Diag(InnerExpr->getBeginLoc(),
           clang::diag::warn_acc_var_referenced_lacks_op)
        << InnerExpr->getType() << CK
        << clang::diag::AccVarReferencedReason::Dtor;
    return ExprError();
  }
  return VarExpr;
}
} // namespace

ExprResult SemaOpenACC::ActOnVar(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
                                 Expr *VarExpr) {
  // This has unique enough restrictions that we should split it to a separate
  // function.
  if (DK == OpenACCDirectiveKind::Cache)
    return ActOnCacheVar(VarExpr);

  Expr *CurVarExpr = VarExpr->IgnoreParenImpCasts();

  // 'use_device' doesn't allow array subscript or array sections.
  // OpenACC3.3 2.8:
  // A 'var' in a 'use_device' clause must be the name of a variable or array.
  // OpenACC3.3 2.13:
  // A 'var' in a 'declare' directive must be a variable or array name.
  if ((CK == OpenACCClauseKind::UseDevice ||
       DK == OpenACCDirectiveKind::Declare)) {
    if (isa<ArraySubscriptExpr>(CurVarExpr)) {
      Diag(VarExpr->getExprLoc(),
           diag::err_acc_not_a_var_ref_use_device_declare)
          << (DK == OpenACCDirectiveKind::Declare);
      return ExprError();
    }
    // As an extension, we allow 'array sections'/'sub-arrays'  here, as that is
    // effectively defining an array, and are in common use.
    if (isa<ArraySectionExpr>(CurVarExpr))
      Diag(VarExpr->getExprLoc(),
           diag::ext_acc_array_section_use_device_declare)
          << (DK == OpenACCDirectiveKind::Declare);
  }

  // Sub-arrays/subscript-exprs are fine as long as the base is a
  // VarExpr/MemberExpr. So strip all of those off.
  while (isa<ArraySectionExpr, ArraySubscriptExpr>(CurVarExpr)) {
    if (auto *SubScrpt = dyn_cast<ArraySubscriptExpr>(CurVarExpr))
      CurVarExpr = SubScrpt->getBase()->IgnoreParenImpCasts();
    else
      CurVarExpr =
          cast<ArraySectionExpr>(CurVarExpr)->getBase()->IgnoreParenImpCasts();
  }

  // References to a VarDecl are fine.
  if (const auto *DRE = dyn_cast<DeclRefExpr>(CurVarExpr)) {
    if (isa<VarDecl, NonTypeTemplateParmDecl>(
            DRE->getFoundDecl()->getCanonicalDecl()))
      return CheckVarType(*this, CK, VarExpr, CurVarExpr);
  }

  // If CK is a Reduction, this special cases for OpenACC3.3 2.5.15: "A var in a
  // reduction clause must be a scalar variable name, an aggregate variable
  // name, an array element, or a subarray.
  // If CK is a 'use_device', this also isn't valid, as it isn't the name of a
  // variable or array, if not done as a member expr.
  // A MemberExpr that references a Field is valid for other clauses.
  if (const auto *ME = dyn_cast<MemberExpr>(CurVarExpr)) {
    if (isa<FieldDecl>(ME->getMemberDecl()->getCanonicalDecl())) {
      if (DK == OpenACCDirectiveKind::Declare ||
          CK == OpenACCClauseKind::Reduction ||
          CK == OpenACCClauseKind::UseDevice) {

        // We can allow 'member expr' if the 'this' is implicit in the case of
        // declare, reduction, and use_device.
        const auto *This = dyn_cast<CXXThisExpr>(ME->getBase());
        if (This && This->isImplicit())
          return CheckVarType(*this, CK, VarExpr, CurVarExpr);
      } else {
        return CheckVarType(*this, CK, VarExpr, CurVarExpr);
      }
    }
  }

  // Referring to 'this' is ok for the most part, but for 'use_device'/'declare'
  // doesn't fall into 'variable or array name'
  if (CK != OpenACCClauseKind::UseDevice &&
      DK != OpenACCDirectiveKind::Declare && isa<CXXThisExpr>(CurVarExpr))
    return CheckVarType(*this, CK, VarExpr, CurVarExpr);

  // Nothing really we can do here, as these are dependent.  So just return they
  // are valid.
  if (isa<DependentScopeDeclRefExpr>(CurVarExpr) ||
      (CK != OpenACCClauseKind::Reduction &&
       isa<CXXDependentScopeMemberExpr>(CurVarExpr)))
    return CheckVarType(*this, CK, VarExpr, CurVarExpr);

  // There isn't really anything we can do in the case of a recovery expr, so
  // skip the diagnostic rather than produce a confusing diagnostic.
  if (isa<RecoveryExpr>(CurVarExpr))
    return ExprError();

  if (DK == OpenACCDirectiveKind::Declare)
    Diag(VarExpr->getExprLoc(), diag::err_acc_not_a_var_ref_use_device_declare)
        << /*declare*/ 1;
  else if (CK == OpenACCClauseKind::UseDevice)
    Diag(VarExpr->getExprLoc(), diag::err_acc_not_a_var_ref_use_device_declare)
        << /*use_device*/ 0;
  else
    Diag(VarExpr->getExprLoc(), diag::err_acc_not_a_var_ref)
        << (CK != OpenACCClauseKind::Reduction);
  return ExprError();
}

ExprResult SemaOpenACC::ActOnArraySectionExpr(Expr *Base, SourceLocation LBLoc,
                                              Expr *LowerBound,
                                              SourceLocation ColonLoc,
                                              Expr *Length,
                                              SourceLocation RBLoc) {
  ASTContext &Context = getASTContext();

  // Handle placeholders.
  if (Base->hasPlaceholderType() &&
      !Base->hasPlaceholderType(BuiltinType::ArraySection)) {
    ExprResult Result = SemaRef.CheckPlaceholderExpr(Base);
    if (Result.isInvalid())
      return ExprError();
    Base = Result.get();
  }
  if (LowerBound && LowerBound->getType()->isNonOverloadPlaceholderType()) {
    ExprResult Result = SemaRef.CheckPlaceholderExpr(LowerBound);
    if (Result.isInvalid())
      return ExprError();
    Result = SemaRef.DefaultLvalueConversion(Result.get());
    if (Result.isInvalid())
      return ExprError();
    LowerBound = Result.get();
  }
  if (Length && Length->getType()->isNonOverloadPlaceholderType()) {
    ExprResult Result = SemaRef.CheckPlaceholderExpr(Length);
    if (Result.isInvalid())
      return ExprError();
    Result = SemaRef.DefaultLvalueConversion(Result.get());
    if (Result.isInvalid())
      return ExprError();
    Length = Result.get();
  }

  // Check the 'base' value, it must be an array or pointer type, and not to/of
  // a function type.
  QualType OriginalBaseTy = ArraySectionExpr::getBaseOriginalType(Base);
  QualType ResultTy;
  if (!Base->isTypeDependent()) {
    if (OriginalBaseTy->isAnyPointerType()) {
      ResultTy = OriginalBaseTy->getPointeeType();
    } else if (OriginalBaseTy->isArrayType()) {
      ResultTy = OriginalBaseTy->getAsArrayTypeUnsafe()->getElementType();
    } else {
      return ExprError(
          Diag(Base->getExprLoc(), diag::err_acc_typecheck_subarray_value)
          << Base->getSourceRange());
    }

    if (ResultTy->isFunctionType()) {
      Diag(Base->getExprLoc(), diag::err_acc_subarray_function_type)
          << ResultTy << Base->getSourceRange();
      return ExprError();
    }

    if (SemaRef.RequireCompleteType(Base->getExprLoc(), ResultTy,
                                    diag::err_acc_subarray_incomplete_type,
                                    Base))
      return ExprError();

    if (!Base->hasPlaceholderType(BuiltinType::ArraySection)) {
      ExprResult Result = SemaRef.DefaultFunctionArrayLvalueConversion(Base);
      if (Result.isInvalid())
        return ExprError();
      Base = Result.get();
    }
  }

  auto GetRecovery = [&](Expr *E, QualType Ty) {
    ExprResult Recovery =
        SemaRef.CreateRecoveryExpr(E->getBeginLoc(), E->getEndLoc(), E, Ty);
    return Recovery.isUsable() ? Recovery.get() : nullptr;
  };

  // Ensure both of the expressions are int-exprs.
  if (LowerBound && !LowerBound->isTypeDependent()) {
    ExprResult LBRes =
        ActOnIntExpr(OpenACCDirectiveKind::Invalid, OpenACCClauseKind::Invalid,
                     LowerBound->getExprLoc(), LowerBound);

    if (LBRes.isUsable())
      LBRes = SemaRef.DefaultLvalueConversion(LBRes.get());
    LowerBound =
        LBRes.isUsable() ? LBRes.get() : GetRecovery(LowerBound, Context.IntTy);
  }

  if (Length && !Length->isTypeDependent()) {
    ExprResult LenRes =
        ActOnIntExpr(OpenACCDirectiveKind::Invalid, OpenACCClauseKind::Invalid,
                     Length->getExprLoc(), Length);

    if (LenRes.isUsable())
      LenRes = SemaRef.DefaultLvalueConversion(LenRes.get());
    Length =
        LenRes.isUsable() ? LenRes.get() : GetRecovery(Length, Context.IntTy);
  }

  // Length is required if the base type is not an array of known bounds.
  if (!Length && (OriginalBaseTy.isNull() ||
                  (!OriginalBaseTy->isDependentType() &&
                   !OriginalBaseTy->isConstantArrayType() &&
                   !OriginalBaseTy->isDependentSizedArrayType()))) {
    bool IsArray = !OriginalBaseTy.isNull() && OriginalBaseTy->isArrayType();
    SourceLocation DiagLoc = ColonLoc.isInvalid() ? LBLoc : ColonLoc;
    Diag(DiagLoc, diag::err_acc_subarray_no_length) << IsArray;
    // Fill in a dummy 'length' so that when we instantiate this we don't
    // double-diagnose here.
    ExprResult Recovery = SemaRef.CreateRecoveryExpr(
        DiagLoc, SourceLocation(), ArrayRef<Expr *>(), Context.IntTy);
    Length = Recovery.isUsable() ? Recovery.get() : nullptr;
  }

  // Check the values of each of the arguments, they cannot be negative(we
  // assume), and if the array bound is known, must be within range. As we do
  // so, do our best to continue with evaluation, we can set the
  // value/expression to nullptr/nullopt if they are invalid, and treat them as
  // not present for the rest of evaluation.

  // We don't have to check for dependence, because the dependent size is
  // represented as a different AST node.
  std::optional<llvm::APSInt> BaseSize;
  if (!OriginalBaseTy.isNull() && OriginalBaseTy->isConstantArrayType()) {
    const auto *ArrayTy = Context.getAsConstantArrayType(OriginalBaseTy);
    BaseSize = ArrayTy->getSize();
  }

  auto GetBoundValue = [&](Expr *E) -> std::optional<llvm::APSInt> {
    if (!E || E->isInstantiationDependent())
      return std::nullopt;

    Expr::EvalResult Res;
    if (!E->EvaluateAsInt(Res, Context))
      return std::nullopt;
    return Res.Val.getInt();
  };

  std::optional<llvm::APSInt> LowerBoundValue = GetBoundValue(LowerBound);
  std::optional<llvm::APSInt> LengthValue = GetBoundValue(Length);

  // Check lower bound for negative or out of range.
  if (LowerBoundValue.has_value()) {
    if (LowerBoundValue->isNegative()) {
      Diag(LowerBound->getExprLoc(), diag::err_acc_subarray_negative)
          << /*LowerBound=*/0 << toString(*LowerBoundValue, /*Radix=*/10);
      LowerBoundValue.reset();
      LowerBound = GetRecovery(LowerBound, LowerBound->getType());
    } else if (BaseSize.has_value() &&
               llvm::APSInt::compareValues(*LowerBoundValue, *BaseSize) >= 0) {
      // Lower bound (start index) must be less than the size of the array.
      Diag(LowerBound->getExprLoc(), diag::err_acc_subarray_out_of_range)
          << /*LowerBound=*/0 << toString(*LowerBoundValue, /*Radix=*/10)
          << toString(*BaseSize, /*Radix=*/10);
      LowerBoundValue.reset();
      LowerBound = GetRecovery(LowerBound, LowerBound->getType());
    }
  }

  // Check length for negative or out of range.
  if (LengthValue.has_value()) {
    if (LengthValue->isNegative()) {
      Diag(Length->getExprLoc(), diag::err_acc_subarray_negative)
          << /*Length=*/1 << toString(*LengthValue, /*Radix=*/10);
      LengthValue.reset();
      Length = GetRecovery(Length, Length->getType());
    } else if (BaseSize.has_value() &&
               llvm::APSInt::compareValues(*LengthValue, *BaseSize) > 0) {
      // Length must be lessthan or EQUAL to the size of the array.
      Diag(Length->getExprLoc(), diag::err_acc_subarray_out_of_range)
          << /*Length=*/1 << toString(*LengthValue, /*Radix=*/10)
          << toString(*BaseSize, /*Radix=*/10);
      LengthValue.reset();
      Length = GetRecovery(Length, Length->getType());
    }
  }

  // Adding two APSInts requires matching sign, so extract that here.
  auto AddAPSInt = [](llvm::APSInt LHS, llvm::APSInt RHS) -> llvm::APSInt {
    if (LHS.isSigned() == RHS.isSigned())
      return LHS + RHS;

    unsigned Width = std::max(LHS.getBitWidth(), RHS.getBitWidth()) + 1;
    return llvm::APSInt(LHS.sext(Width) + RHS.sext(Width), /*Signed=*/true);
  };

  // If we know all 3 values, we can diagnose that the total value would be out
  // of range.
  if (BaseSize.has_value() && LowerBoundValue.has_value() &&
      LengthValue.has_value() &&
      llvm::APSInt::compareValues(AddAPSInt(*LowerBoundValue, *LengthValue),
                                  *BaseSize) > 0) {
    Diag(Base->getExprLoc(),
         diag::err_acc_subarray_base_plus_length_out_of_range)
        << toString(*LowerBoundValue, /*Radix=*/10)
        << toString(*LengthValue, /*Radix=*/10)
        << toString(*BaseSize, /*Radix=*/10);

    LowerBoundValue.reset();
    LowerBound = GetRecovery(LowerBound, LowerBound->getType());
    LengthValue.reset();
    Length = GetRecovery(Length, Length->getType());
  }

  // If any part of the expression is dependent, return a dependent sub-array.
  QualType ArrayExprTy = Context.ArraySectionTy;
  if (Base->isTypeDependent() ||
      (LowerBound && LowerBound->isInstantiationDependent()) ||
      (Length && Length->isInstantiationDependent()))
    ArrayExprTy = Context.DependentTy;

  return new (Context)
      ArraySectionExpr(Base, LowerBound, Length, ArrayExprTy, VK_LValue,
                       OK_Ordinary, ColonLoc, RBLoc);
}

void SemaOpenACC::ActOnWhileStmt(SourceLocation WhileLoc) {
  if (!getLangOpts().OpenACC)
    return;

  if (!LoopInfo.TopLevelLoopSeen)
    return;

  if (CollapseInfo.CurCollapseCount && *CollapseInfo.CurCollapseCount > 0) {
    Diag(WhileLoc, diag::err_acc_invalid_in_loop)
        << /*while loop*/ 1 << CollapseInfo.DirectiveKind
        << OpenACCClauseKind::Collapse;
    assert(CollapseInfo.ActiveCollapse && "Collapse count without object?");
    Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
         diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Collapse;

    // Remove the value so that we don't get cascading errors in the body. The
    // caller RAII object will restore this.
    CollapseInfo.CurCollapseCount = std::nullopt;
  }

  if (TileInfo.CurTileCount && *TileInfo.CurTileCount > 0) {
    Diag(WhileLoc, diag::err_acc_invalid_in_loop)
        << /*while loop*/ 1 << TileInfo.DirectiveKind
        << OpenACCClauseKind::Tile;
    assert(TileInfo.ActiveTile && "tile count without object?");
    Diag(TileInfo.ActiveTile->getBeginLoc(), diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Tile;

    // Remove the value so that we don't get cascading errors in the body. The
    // caller RAII object will restore this.
    TileInfo.CurTileCount = std::nullopt;
  }
}

void SemaOpenACC::ActOnDoStmt(SourceLocation DoLoc) {
  if (!getLangOpts().OpenACC)
    return;

  if (!LoopInfo.TopLevelLoopSeen)
    return;

  if (CollapseInfo.CurCollapseCount && *CollapseInfo.CurCollapseCount > 0) {
    Diag(DoLoc, diag::err_acc_invalid_in_loop)
        << /*do loop*/ 2 << CollapseInfo.DirectiveKind
        << OpenACCClauseKind::Collapse;
    assert(CollapseInfo.ActiveCollapse && "Collapse count without object?");
    Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
         diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Collapse;

    // Remove the value so that we don't get cascading errors in the body. The
    // caller RAII object will restore this.
    CollapseInfo.CurCollapseCount = std::nullopt;
  }

  if (TileInfo.CurTileCount && *TileInfo.CurTileCount > 0) {
    Diag(DoLoc, diag::err_acc_invalid_in_loop)
        << /*do loop*/ 2 << TileInfo.DirectiveKind << OpenACCClauseKind::Tile;
    assert(TileInfo.ActiveTile && "tile count without object?");
    Diag(TileInfo.ActiveTile->getBeginLoc(), diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Tile;

    // Remove the value so that we don't get cascading errors in the body. The
    // caller RAII object will restore this.
    TileInfo.CurTileCount = std::nullopt;
  }
}

void SemaOpenACC::ForStmtBeginHelper(SourceLocation ForLoc,
                                     ForStmtBeginChecker &C) {
  assert(getLangOpts().OpenACC && "Check enabled when not OpenACC?");

  // Enable the while/do-while checking.
  LoopInfo.TopLevelLoopSeen = true;

  if (CollapseInfo.CurCollapseCount && *CollapseInfo.CurCollapseCount > 0) {
    // Check the format of this loop if it is affected by the collapse.
    C.check();

    // OpenACC 3.3 2.9.1:
    // Each associated loop, except the innermost, must contain exactly one loop
    // or loop nest.
    // This checks for more than 1 loop at the current level, the
    // 'depth'-satisifed checking manages the 'not zero' case.
    if (LoopInfo.CurLevelHasLoopAlready) {
      Diag(ForLoc, diag::err_acc_clause_multiple_loops)
          << CollapseInfo.DirectiveKind << OpenACCClauseKind::Collapse;
      assert(CollapseInfo.ActiveCollapse && "No collapse object?");
      Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
           diag::note_acc_active_clause_here)
          << OpenACCClauseKind::Collapse;
    } else {
      --(*CollapseInfo.CurCollapseCount);

      // Once we've hit zero here, we know we have deep enough 'for' loops to
      // get to the bottom.
      if (*CollapseInfo.CurCollapseCount == 0)
        CollapseInfo.CollapseDepthSatisfied = true;
    }
  }

  if (TileInfo.CurTileCount && *TileInfo.CurTileCount > 0) {
    // Check the format of this loop if it is affected by the tile.
    C.check();

    if (LoopInfo.CurLevelHasLoopAlready) {
      Diag(ForLoc, diag::err_acc_clause_multiple_loops)
          << TileInfo.DirectiveKind << OpenACCClauseKind::Tile;
      assert(TileInfo.ActiveTile && "No tile object?");
      Diag(TileInfo.ActiveTile->getBeginLoc(),
           diag::note_acc_active_clause_here)
          << OpenACCClauseKind::Tile;
    } else {
      TileInfo.CurTileCount = *TileInfo.CurTileCount - 1;
      // Once we've hit zero here, we know we have deep enough 'for' loops to
      // get to the bottom.
      if (*TileInfo.CurTileCount == 0)
        TileInfo.TileDepthSatisfied = true;
    }
  }

  // Set this to 'false' for the body of this loop, so that the next level
  // checks independently.
  LoopInfo.CurLevelHasLoopAlready = false;
}

namespace {
bool isValidLoopVariableType(QualType LoopVarTy) {
  // Just skip if it is dependent, it could be any of the below.
  if (LoopVarTy->isDependentType())
    return true;

  // The loop variable must be of integer,
  if (LoopVarTy->isIntegerType())
    return true;

  // C/C++ pointer,
  if (LoopVarTy->isPointerType())
    return true;

  // or C++ random-access iterator type.
  if (const auto *RD = LoopVarTy->getAsCXXRecordDecl()) {
    // Note: Only do CXXRecordDecl because RecordDecl can't be a random access
    // iterator type!

    // We could either do a lot of work to see if this matches
    // random-access-iterator, but it seems that just checking that the
    // 'iterator_category' typedef is more than sufficient. If programmers are
    // willing to lie about this, we can let them.

    for (const auto *TD :
         llvm::make_filter_range(RD->decls(), llvm::IsaPred<TypedefNameDecl>)) {
      const auto *TDND = cast<TypedefNameDecl>(TD)->getCanonicalDecl();

      if (TDND->getName() != "iterator_category")
        continue;

      // If there is no type for this decl, return false.
      if (TDND->getUnderlyingType().isNull())
        return false;

      const CXXRecordDecl *ItrCategoryDecl =
          TDND->getUnderlyingType()->getAsCXXRecordDecl();

      // If the category isn't a record decl, it isn't the tag type.
      if (!ItrCategoryDecl)
        return false;

      auto IsRandomAccessIteratorTag = [](const CXXRecordDecl *RD) {
        if (RD->getName() != "random_access_iterator_tag")
          return false;
        // Checks just for std::random_access_iterator_tag.
        return RD->getEnclosingNamespaceContext()->isStdNamespace();
      };

      if (IsRandomAccessIteratorTag(ItrCategoryDecl))
        return true;

      // We can also support tag-types inherited from the
      // random_access_iterator_tag.
      for (CXXBaseSpecifier BS : ItrCategoryDecl->bases())
        if (IsRandomAccessIteratorTag(BS.getType()->getAsCXXRecordDecl()))
          return true;

      return false;
    }
  }

  return false;
}
const ValueDecl *getDeclFromExpr(const Expr *E) {
  E = E->IgnoreParenImpCasts();
  if (const auto *FE = dyn_cast<FullExpr>(E))
    E = FE->getSubExpr();

  E = E->IgnoreParenImpCasts();

  if (!E)
    return nullptr;
  if (const auto *DRE = dyn_cast<DeclRefExpr>(E))
    return dyn_cast<ValueDecl>(DRE->getDecl());

  if (const auto *ME = dyn_cast<MemberExpr>(E))
    if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts()))
      return ME->getMemberDecl();

  return nullptr;
}
} // namespace

void SemaOpenACC::ForStmtBeginChecker::checkRangeFor() {
  const RangeForInfo &RFI = std::get<RangeForInfo>(Info);
  // If this hasn't changed since last instantiated we're done.
  if (RFI.Uninstantiated == RFI.CurrentVersion)
    return;

  const DeclStmt *UninstRangeStmt =
      IsInstantiation ? RFI.Uninstantiated->getBeginStmt() : nullptr;
  const DeclStmt *RangeStmt = RFI.CurrentVersion->getBeginStmt();

  // If this isn't the first time we've checked this loop, suppress any cases
  // where we previously diagnosed.
  if (UninstRangeStmt) {
    const ValueDecl *InitVar =
        cast<ValueDecl>(UninstRangeStmt->getSingleDecl());
    QualType VarType = InitVar->getType().getNonReferenceType();

    if (!isValidLoopVariableType(VarType))
      return;
  }

  // In some dependent contexts, the autogenerated range statement doesn't get
  // included until instantiation, so skip for now.
  if (RangeStmt) {
    const ValueDecl *InitVar = cast<ValueDecl>(RangeStmt->getSingleDecl());
    QualType VarType = InitVar->getType().getNonReferenceType();

    if (!isValidLoopVariableType(VarType)) {
      SemaRef.Diag(InitVar->getBeginLoc(), diag::err_acc_loop_variable_type)
          << SemaRef.LoopWithoutSeqInfo.Kind << VarType;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      return;
    }
  }
}
bool SemaOpenACC::ForStmtBeginChecker::checkForInit(const Stmt *InitStmt,
                                                    const ValueDecl *&InitVar,
                                                    bool Diag) {
  // Init statement is required.
  if (!InitStmt) {
    if (Diag) {
      SemaRef.Diag(ForLoc, diag::err_acc_loop_variable)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  }
  auto DiagLoopVar = [this, Diag, InitStmt]() {
    if (Diag) {
      SemaRef.Diag(InitStmt->getBeginLoc(), diag::err_acc_loop_variable)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  };

  if (const auto *ExprTemp = dyn_cast<ExprWithCleanups>(InitStmt))
    InitStmt = ExprTemp->getSubExpr();
  if (const auto *E = dyn_cast<Expr>(InitStmt))
    InitStmt = E->IgnoreParenImpCasts();

  InitVar = nullptr;
  if (const auto *BO = dyn_cast<BinaryOperator>(InitStmt)) {
    // Allow assignment operator here.

    if (!BO->isAssignmentOp())
      return DiagLoopVar();

    const Expr *LHS = BO->getLHS()->IgnoreParenImpCasts();
    if (const auto *DRE = dyn_cast<DeclRefExpr>(LHS))
      InitVar = DRE->getDecl();
  } else if (const auto *DS = dyn_cast<DeclStmt>(InitStmt)) {
    // Allow T t = <whatever>
    if (!DS->isSingleDecl())
      return DiagLoopVar();
    InitVar = dyn_cast<ValueDecl>(DS->getSingleDecl());

    // Ensure we have an initializer, unless this is a record/dependent type.
    if (InitVar) {
      if (!isa<VarDecl>(InitVar))
        return DiagLoopVar();

      if (!InitVar->getType()->isRecordType() &&
          !InitVar->getType()->isDependentType() &&
          !cast<VarDecl>(InitVar)->hasInit())
        return DiagLoopVar();
    }
  } else if (auto *CE = dyn_cast<CXXOperatorCallExpr>(InitStmt)) {
    // Allow assignment operator call.
    if (CE->getOperator() != OO_Equal)
      return DiagLoopVar();

    const Expr *LHS = CE->getArg(0)->IgnoreParenImpCasts();
    if (auto *DRE = dyn_cast<DeclRefExpr>(LHS)) {
      InitVar = DRE->getDecl();
    } else if (auto *ME = dyn_cast<MemberExpr>(LHS)) {
      if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts()))
        InitVar = ME->getMemberDecl();
    }
  }

  // If after all of that, we haven't found a variable, give up.
  if (!InitVar)
    return DiagLoopVar();

  InitVar = cast<ValueDecl>(InitVar->getCanonicalDecl());
  QualType VarType = InitVar->getType().getNonReferenceType();

  // Since we have one, all we need to do is ensure it is the right type.
  if (!isValidLoopVariableType(VarType)) {
    if (Diag) {
      SemaRef.Diag(InitVar->getBeginLoc(), diag::err_acc_loop_variable_type)
          << SemaRef.LoopWithoutSeqInfo.Kind << VarType;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  }

  return false;
}

bool SemaOpenACC::ForStmtBeginChecker::checkForCond(const Stmt *CondStmt,
                                                    const ValueDecl *InitVar,
                                                    bool Diag) {
  // A condition statement is required.
  if (!CondStmt) {
    if (Diag) {
      SemaRef.Diag(ForLoc, diag::err_acc_loop_terminating_condition)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }

    return true;
  }
  auto DiagCondVar = [this, Diag, CondStmt] {
    if (Diag) {
      SemaRef.Diag(CondStmt->getBeginLoc(),
                   diag::err_acc_loop_terminating_condition)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  };

  if (const auto *ExprTemp = dyn_cast<ExprWithCleanups>(CondStmt))
    CondStmt = ExprTemp->getSubExpr();
  if (const auto *E = dyn_cast<Expr>(CondStmt))
    CondStmt = E->IgnoreParenImpCasts();

  const ValueDecl *CondVar = nullptr;
  if (const auto *BO = dyn_cast<BinaryOperator>(CondStmt)) {
    switch (BO->getOpcode()) {
    default:
      return DiagCondVar();
    case BO_EQ:
    case BO_LT:
    case BO_GT:
    case BO_NE:
    case BO_LE:
    case BO_GE:
      break;
    }

    // Assign the condition-var to the LHS.  If it either comes back null, or
    // the LHS doesn't match the InitVar, assign it to the RHS so that 5 < N is
    // allowed.
    CondVar = getDeclFromExpr(BO->getLHS());
    if (!CondVar ||
        (InitVar && CondVar->getCanonicalDecl() != InitVar->getCanonicalDecl()))
      CondVar = getDeclFromExpr(BO->getRHS());

  } else if (const auto *CE = dyn_cast<CXXOperatorCallExpr>(CondStmt)) {
    // Any of the comparison ops should be ok here, but we don't know how to
    // handle spaceship, so disallow for now.
    if (!CE->isComparisonOp() || CE->getOperator() == OO_Spaceship)
      return DiagCondVar();

    // Same logic here: Assign it to the LHS, unless the LHS comes back null or
    // not equal to the init var.
    CondVar = getDeclFromExpr(CE->getArg(0));
    if (!CondVar ||
        (InitVar &&
         CondVar->getCanonicalDecl() != InitVar->getCanonicalDecl() &&
         CE->getNumArgs() > 1))
      CondVar = getDeclFromExpr(CE->getArg(1));
  } else {
    return DiagCondVar();
  }

  if (!CondVar)
    return DiagCondVar();

  // Don't consider this an error unless the init variable was properly set,
  // else check to make sure they are the same variable.
  if (InitVar && CondVar->getCanonicalDecl() != InitVar->getCanonicalDecl())
    return DiagCondVar();

  return false;
}

namespace {
// Helper to check the RHS of an assignment during for's step. We can allow
// InitVar = InitVar + N, InitVar = N + InitVar, and Initvar = Initvar - N,
// where N is an integer.
bool isValidForIncRHSAssign(const ValueDecl *InitVar, const Expr *RHS) {

  auto isValid = [](const ValueDecl *InitVar, const Expr *InnerLHS,
                    const Expr *InnerRHS, bool IsAddition) {
    // ONE of the sides has to be an integer type.
    if (!InnerLHS->getType()->isIntegerType() &&
        !InnerRHS->getType()->isIntegerType())
      return false;

    // If the init var is already an error, don't bother trying to check for
    // it.
    if (!InitVar)
      return true;

    const ValueDecl *LHSDecl = getDeclFromExpr(InnerLHS);
    const ValueDecl *RHSDecl = getDeclFromExpr(InnerRHS);
    // If we can't get a declaration, this is probably an error, so give up.
    if (!LHSDecl || !RHSDecl)
      return true;

    // If the LHS is the InitVar, the other must be int, so this is valid.
    if (LHSDecl->getCanonicalDecl() ==
        InitVar->getCanonicalDecl())
      return true;

    // Subtraction doesn't allow the RHS to be init var, so this is invalid.
    if (!IsAddition)
      return false;

    return RHSDecl->getCanonicalDecl() ==
           InitVar->getCanonicalDecl();
  };

  if (const auto *BO = dyn_cast<BinaryOperator>(RHS)) {
    BinaryOperatorKind OpC = BO->getOpcode();
    if (OpC != BO_Add && OpC != BO_Sub)
      return false;
    return isValid(InitVar, BO->getLHS(), BO->getRHS(), OpC == BO_Add);
  } else if (const auto *CE = dyn_cast<CXXOperatorCallExpr>(RHS)) {
    OverloadedOperatorKind Op = CE->getOperator();
    if (Op != OO_Plus && Op != OO_Minus)
      return false;
    return isValid(InitVar, CE->getArg(0), CE->getArg(1), Op == OO_Plus);
  }

  return false;
}
} // namespace

bool SemaOpenACC::ForStmtBeginChecker::checkForInc(const Stmt *IncStmt,
                                                   const ValueDecl *InitVar,
                                                   bool Diag) {
  if (!IncStmt) {
    if (Diag) {
      SemaRef.Diag(ForLoc, diag::err_acc_loop_not_monotonic)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  }
  auto DiagIncVar = [this, Diag, IncStmt] {
    if (Diag) {
      SemaRef.Diag(IncStmt->getBeginLoc(), diag::err_acc_loop_not_monotonic)
          << SemaRef.LoopWithoutSeqInfo.Kind;
      SemaRef.Diag(SemaRef.LoopWithoutSeqInfo.Loc,
                   diag::note_acc_construct_here)
          << SemaRef.LoopWithoutSeqInfo.Kind;
    }
    return true;
  };

  if (const auto *ExprTemp = dyn_cast<ExprWithCleanups>(IncStmt))
    IncStmt = ExprTemp->getSubExpr();
  if (const auto *E = dyn_cast<Expr>(IncStmt))
    IncStmt = E->IgnoreParenImpCasts();

  const ValueDecl *IncVar = nullptr;
  // Here we enforce the monotonically increase/decrease:
  if (const auto *UO = dyn_cast<UnaryOperator>(IncStmt)) {
    // Allow increment/decrement ops.
    if (!UO->isIncrementDecrementOp())
      return DiagIncVar();
    IncVar = getDeclFromExpr(UO->getSubExpr());
  } else if (const auto *BO = dyn_cast<BinaryOperator>(IncStmt)) {
    switch (BO->getOpcode()) {
    default:
      return DiagIncVar();
    case BO_AddAssign:
    case BO_SubAssign:
      break;
    case BO_Assign:
      // For assignment we also allow InitVar = InitVar + N, InitVar = N +
      // InitVar, and InitVar = InitVar - N;  BUT only if 'N' is integral.
      if (!isValidForIncRHSAssign(InitVar, BO->getRHS()))
        return DiagIncVar();
      break;
    }
    IncVar = getDeclFromExpr(BO->getLHS());
  } else if (const auto *CE = dyn_cast<CXXOperatorCallExpr>(IncStmt)) {
    switch (CE->getOperator()) {
    default:
      return DiagIncVar();
    case OO_PlusPlus:
    case OO_MinusMinus:
    case OO_PlusEqual:
    case OO_MinusEqual:
      break;
    case OO_Equal:
      // For assignment we also allow InitVar = InitVar + N, InitVar = N +
      // InitVar, and InitVar = InitVar - N;  BUT only if 'N' is integral.
      if (!isValidForIncRHSAssign(InitVar, CE->getArg(1)))
        return DiagIncVar();
      break;
    }

    IncVar = getDeclFromExpr(CE->getArg(0));
  } else {
    return DiagIncVar();
  }

  if (!IncVar)
    return DiagIncVar();

  // InitVar shouldn't be null unless there was an error, so don't diagnose if
  // that is the case. Else we should ensure that it refers to the  loop
  // value.
  if (InitVar && IncVar->getCanonicalDecl() != InitVar->getCanonicalDecl())
    return DiagIncVar();

  return false;
}

void SemaOpenACC::ForStmtBeginChecker::checkFor() {
  const CheckForInfo &CFI = std::get<CheckForInfo>(Info);

  if (!IsInstantiation) {
    // If this isn't an instantiation, we can just check all of these and
    // diagnose.
    const ValueDecl *CurInitVar = nullptr;
    checkForInit(CFI.Current.Init, CurInitVar, /*Diag=*/true);
    checkForCond(CFI.Current.Condition, CurInitVar, /*Diag=*/true);
    checkForInc(CFI.Current.Increment, CurInitVar, /*DIag=*/true);
  } else {
    const ValueDecl *UninstInitVar = nullptr;
    // Checking the 'init' section first. We have to always run both versions,
    // at minimum with the 'diag' off, so that we can ensure we get the correct
    // instantiation var for checking by later ones.
    bool UninstInitFailed =
        checkForInit(CFI.Uninst.Init, UninstInitVar, /*Diag=*/false);

    // VarDecls are always rebuild because they are dependent, so we can do a
    // little work to suppress some of the double checking based on whether the
    // type is instantiation dependent. This is imperfect, but will get us most
    // cases suppressed. Currently this only handles the 'T t =' case.
    auto InitChanged = [=]() {
      if (CFI.Uninst.Init == CFI.Current.Init)
        return false;

      QualType OldVDTy;
      QualType NewVDTy;

      if (const auto *DS = dyn_cast<DeclStmt>(CFI.Uninst.Init))
        if (const VarDecl *VD = dyn_cast_if_present<VarDecl>(
                DS->isSingleDecl() ? DS->getSingleDecl() : nullptr))
          OldVDTy = VD->getType();
      if (const auto *DS = dyn_cast<DeclStmt>(CFI.Current.Init))
        if (const VarDecl *VD = dyn_cast_if_present<VarDecl>(
                DS->isSingleDecl() ? DS->getSingleDecl() : nullptr))
          NewVDTy = VD->getType();

      if (OldVDTy.isNull() || NewVDTy.isNull())
        return true;

      return OldVDTy->isInstantiationDependentType() !=
             NewVDTy->isInstantiationDependentType();
    };

    // Only diagnose the new 'init' if the previous version didn't fail, AND the
    // current init changed meaningfully.
    bool ShouldDiagNewInit = !UninstInitFailed && InitChanged();
    const ValueDecl *CurInitVar = nullptr;
    checkForInit(CFI.Current.Init, CurInitVar, /*Diag=*/ShouldDiagNewInit);

    // Check the condition and increment only if the previous version passed,
    // and this changed.
    if (CFI.Uninst.Condition != CFI.Current.Condition &&
        !checkForCond(CFI.Uninst.Condition, UninstInitVar, /*Diag=*/false))
      checkForCond(CFI.Current.Condition, CurInitVar, /*Diag=*/true);
    if (CFI.Uninst.Increment != CFI.Current.Increment &&
        !checkForInc(CFI.Uninst.Increment, UninstInitVar, /*Diag=*/false))
      checkForInc(CFI.Current.Increment, CurInitVar, /*Diag=*/true);
  }
}

void SemaOpenACC::ForStmtBeginChecker::check() {
  // If this isn't an active loop without a seq, immediately return, nothing to
  // check.
  if (SemaRef.LoopWithoutSeqInfo.Kind == OpenACCDirectiveKind::Invalid)
    return;

  // If we've already checked, because this is a 'top level' one (and asking
  // again because 'tile' and 'collapse' might apply), just return, nothing to
  // do here.
  if (AlreadyChecked)
    return;
  AlreadyChecked = true;

  // OpenACC3.3 2.1:
  // A loop associated with a loop construct that does not have a seq clause
  // must be written to meet all the following conditions:
  // - The loop variable must be of integer, C/C++ pointer, or C++ random-access
  // iterator type.
  // - The loop variable must monotonically increase or decrease in the
  // direction of its termination condition.
  // - The loop trip count must be computable in constant time when entering the
  // loop construct.
  //
  // For a C++ range-based for loop, the loop variable
  // identified by the above conditions is the internal iterator, such as a
  // pointer, that the compiler generates to iterate the range.  it is not the
  // variable declared by the for loop.

  if (std::holds_alternative<RangeForInfo>(Info))
    return checkRangeFor();

  return checkFor();
}

void SemaOpenACC::ActOnForStmtBegin(SourceLocation ForLoc, const Stmt *OldFirst,
                                    const Stmt *First, const Stmt *OldSecond,
                                    const Stmt *Second, const Stmt *OldThird,
                                    const Stmt *Third) {
  if (!getLangOpts().OpenACC)
    return;

  ForStmtBeginChecker FSBC{*this,    ForLoc, OldFirst, OldSecond,
                           OldThird, First,  Second,   Third};
  // Check if this is the top-level 'for' for a 'loop'.  Else it will be checked
  // as a part of the helper if a tile/collapse applies.
  if (!LoopInfo.TopLevelLoopSeen) {
    FSBC.check();
  }

  ForStmtBeginHelper(ForLoc, FSBC);
}

void SemaOpenACC::ActOnForStmtBegin(SourceLocation ForLoc, const Stmt *First,
                                    const Stmt *Second, const Stmt *Third) {
  if (!getLangOpts().OpenACC)
    return;

  ForStmtBeginChecker FSBC{*this, ForLoc, First, Second, Third};

  // Check if this is the top-level 'for' for a 'loop'.  Else it will be checked
  // as a part of the helper if a tile/collapse applies.
  if (!LoopInfo.TopLevelLoopSeen)
    FSBC.check();

  ForStmtBeginHelper(ForLoc, FSBC);
}

void SemaOpenACC::ActOnRangeForStmtBegin(SourceLocation ForLoc,
                                         const Stmt *OldRangeFor,
                                         const Stmt *RangeFor) {
  if (!getLangOpts().OpenACC || OldRangeFor == nullptr || RangeFor == nullptr)
    return;

  ForStmtBeginChecker FSBC{*this, ForLoc,
                           cast_if_present<CXXForRangeStmt>(OldRangeFor),
                           cast_if_present<CXXForRangeStmt>(RangeFor)};
  // Check if this is the top-level 'for' for a 'loop'.  Else it will be checked
  // as a part of the helper if a tile/collapse applies.
  if (!LoopInfo.TopLevelLoopSeen) {
    FSBC.check();
  }
  ForStmtBeginHelper(ForLoc, FSBC);
}

void SemaOpenACC::ActOnRangeForStmtBegin(SourceLocation ForLoc,
                                         const Stmt *RangeFor) {
  if (!getLangOpts().OpenACC || RangeFor == nullptr)
    return;

  ForStmtBeginChecker FSBC = {*this, ForLoc,
                              cast_if_present<CXXForRangeStmt>(RangeFor)};

  // Check if this is the top-level 'for' for a 'loop'.  Else it will be checked
  // as a part of the helper if a tile/collapse applies.
  if (!LoopInfo.TopLevelLoopSeen)
    FSBC.check();

  ForStmtBeginHelper(ForLoc, FSBC);
}

namespace {
SourceLocation FindInterveningCodeInLoop(const Stmt *CurStmt) {
  // We should diagnose on anything except `CompoundStmt`, `NullStmt`,
  // `ForStmt`, `CXXForRangeStmt`, since those are legal, and `WhileStmt` and
  // `DoStmt`, as those are caught as a violation elsewhere.
  // For `CompoundStmt` we need to search inside of it.
  if (!CurStmt ||
      isa<ForStmt, NullStmt, ForStmt, CXXForRangeStmt, WhileStmt, DoStmt>(
          CurStmt))
    return SourceLocation{};

  // Any other construct is an error anyway, so it has already been diagnosed.
  if (isa<OpenACCConstructStmt>(CurStmt))
    return SourceLocation{};

  // Search inside the compound statement, this allows for arbitrary nesting
  // of compound statements, as long as there isn't any code inside.
  if (const auto *CS = dyn_cast<CompoundStmt>(CurStmt)) {
    for (const auto *ChildStmt : CS->children()) {
      SourceLocation ChildStmtLoc = FindInterveningCodeInLoop(ChildStmt);
      if (ChildStmtLoc.isValid())
        return ChildStmtLoc;
    }
    // Empty/not invalid compound statements are legal.
    return SourceLocation{};
  }
  return CurStmt->getBeginLoc();
}
} // namespace

void SemaOpenACC::ActOnForStmtEnd(SourceLocation ForLoc, StmtResult Body) {
  if (!getLangOpts().OpenACC)
    return;

  // Set this to 'true' so if we find another one at this level we can diagnose.
  LoopInfo.CurLevelHasLoopAlready = true;

  if (!Body.isUsable())
    return;

  bool IsActiveCollapse = CollapseInfo.CurCollapseCount &&
                          *CollapseInfo.CurCollapseCount > 0 &&
                          !CollapseInfo.ActiveCollapse->hasForce();
  bool IsActiveTile = TileInfo.CurTileCount && *TileInfo.CurTileCount > 0;

  if (IsActiveCollapse || IsActiveTile) {
    SourceLocation OtherStmtLoc = FindInterveningCodeInLoop(Body.get());

    if (OtherStmtLoc.isValid() && IsActiveCollapse) {
      Diag(OtherStmtLoc, diag::err_acc_intervening_code)
          << OpenACCClauseKind::Collapse << CollapseInfo.DirectiveKind;
      Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
           diag::note_acc_active_clause_here)
          << OpenACCClauseKind::Collapse;
    }

    if (OtherStmtLoc.isValid() && IsActiveTile) {
      Diag(OtherStmtLoc, diag::err_acc_intervening_code)
          << OpenACCClauseKind::Tile << TileInfo.DirectiveKind;
      Diag(TileInfo.ActiveTile->getBeginLoc(),
           diag::note_acc_active_clause_here)
          << OpenACCClauseKind::Tile;
    }
  }
}

namespace {
// Helper that should mirror ActOnRoutineName to get the FunctionDecl out for
// magic-static checking.
FunctionDecl *getFunctionFromRoutineName(Expr *RoutineName) {
  if (!RoutineName)
    return nullptr;
  RoutineName = RoutineName->IgnoreParenImpCasts();
  if (isa<RecoveryExpr>(RoutineName)) {
    // There is nothing we can do here, this isn't a function we can count on.
    return nullptr;
  } else if (isa<DependentScopeDeclRefExpr, CXXDependentScopeMemberExpr>(
                 RoutineName)) {
    // The lookup is dependent, so we'll have to figure this out later.
    return nullptr;
  } else if (auto *DRE = dyn_cast<DeclRefExpr>(RoutineName)) {
    ValueDecl *VD = DRE->getDecl();

    if (auto *FD = dyn_cast<FunctionDecl>(VD))
      return FD;

    // Allow lambdas.
    if (auto *VarD = dyn_cast<VarDecl>(VD)) {
      QualType VarDTy = VarD->getType();
      if (!VarDTy.isNull()) {
        if (auto *RD = VarDTy->getAsCXXRecordDecl()) {
          if (RD->isGenericLambda())
            return nullptr;
          if (RD->isLambda())
            return RD->getLambdaCallOperator();
        } else if (VarDTy->isDependentType()) {
          // We don't really know what this is going to be.
          return nullptr;
        }
      }
      return nullptr;
    } else if (isa<OverloadExpr>(RoutineName)) {
      return nullptr;
    }
  }
  return nullptr;
}
} // namespace

ExprResult SemaOpenACC::ActOnRoutineName(Expr *RoutineName) {
  assert(RoutineName && "Routine name cannot be null here");
  RoutineName = RoutineName->IgnoreParenImpCasts();

  if (isa<RecoveryExpr>(RoutineName)) {
    // This has already been diagnosed, so we can skip it.
    return ExprError();
  } else if (isa<DependentScopeDeclRefExpr, CXXDependentScopeMemberExpr>(
                 RoutineName)) {
    // These are dependent and we can't really check them, so delay until
    // instantiation.
    return RoutineName;
  } else if (const auto *DRE = dyn_cast<DeclRefExpr>(RoutineName)) {
    const ValueDecl *VD = DRE->getDecl();

    if (isa<FunctionDecl>(VD))
      return RoutineName;

    // Allow lambdas.
    if (const auto *VarD = dyn_cast<VarDecl>(VD)) {
      QualType VarDTy = VarD->getType();
      if (!VarDTy.isNull()) {
        if (const auto *RD = VarDTy->getAsCXXRecordDecl()) {
          if (RD->isGenericLambda()) {
            Diag(RoutineName->getBeginLoc(), diag::err_acc_routine_overload_set)
                << RoutineName;
            return ExprError();
          }
          if (RD->isLambda())
            return RoutineName;
        } else if (VarDTy->isDependentType()) {
          // If this is a dependent variable, it might be a lambda. So we just
          // accept this and catch it next time.
          return RoutineName;
        }
      }
    }

    Diag(RoutineName->getBeginLoc(), diag::err_acc_routine_not_func)
        << RoutineName;
    return ExprError();
  } else if (isa<OverloadExpr>(RoutineName)) {
    // This happens in function templates, even when the template arguments are
    // fully specified. We could possibly do some sort of matching to make sure
    // that this is looked up/deduced, but GCC does not do this, so there
    // doesn't seem to be a good reason for us to do it either.
    Diag(RoutineName->getBeginLoc(), diag::err_acc_routine_overload_set)
        << RoutineName;
    return ExprError();
  }

  Diag(RoutineName->getBeginLoc(), diag::err_acc_routine_not_func)
      << RoutineName;
  return ExprError();
}
void SemaOpenACC::ActOnVariableDeclarator(VarDecl *VD) {
  if (!getLangOpts().OpenACC || VD->isInvalidDecl() || !VD->isStaticLocal())
    return;

  // This cast should be safe, since a static-local can only happen in a
  // function declaration.
  auto *ContextDecl = cast<FunctionDecl>(getCurContext());

  // OpenACC 3.3 2.15:
  // In C and C++, function static variables are not supported in functions to
  // which a routine directive applies.
  for (const auto *A : ContextDecl->attrs()) {
    if (isa<OpenACCRoutineDeclAttr, OpenACCRoutineAnnotAttr>(A)) {
      Diag(VD->getBeginLoc(), diag::err_acc_magic_static_in_routine);
      Diag(A->getLocation(), diag::note_acc_construct_here)
          << OpenACCDirectiveKind::Routine;
      return;
    }
  }

  MagicStaticLocs.insert({ContextDecl->getCanonicalDecl(), VD->getBeginLoc()});
}
void SemaOpenACC::CheckLastRoutineDeclNameConflict(const NamedDecl *ND) {
  // OpenACC 3.3 A.3.4
  // When a procedure with that name is in scope and it is not the same
  // procedure as the immediately following procedure declaration or
  // definition, the resolution of the name can be confusing.  Implementations
  // should then issue a compile-time warning diagnostic even though the
  // application is conforming.

  // If we haven't created one, also can't diagnose.
  if (!LastRoutineDecl)
    return;

  // If the currently created function doesn't have a name, we can't diagnose on
  // a match.
  if (!ND->getDeclName().isIdentifier())
    return;

  // If the two are in different decl contexts, it doesn't make sense to
  // diagnose.
  if (LastRoutineDecl->getDeclContext() != ND->getLexicalDeclContext())
    return;

  // If we don't have a referenced thing yet, we can't diagnose.
  FunctionDecl *RoutineTarget =
      getFunctionFromRoutineName(LastRoutineDecl->getFunctionReference());
  if (!RoutineTarget)
    return;

  // If the Routine target doesn't have a name, we can't diagnose.
  if (!RoutineTarget->getDeclName().isIdentifier())
    return;

  // Of course don't diagnose if the names don't match.
  if (ND->getName() != RoutineTarget->getName())
    return;

  long NDLine = SemaRef.SourceMgr.getSpellingLineNumber(ND->getBeginLoc());
  long LastLine =
      SemaRef.SourceMgr.getSpellingLineNumber(LastRoutineDecl->getBeginLoc());

  // Do some line-number math to make sure they are within a line of eachother.
  // Comments or newlines can be inserted to clarify intent.
  if (NDLine - LastLine > 1)
    return;

  // Don't warn if it actually DOES apply to this function via redecls.
  if (ND->getCanonicalDecl() == RoutineTarget->getCanonicalDecl())
    return;

  Diag(LastRoutineDecl->getFunctionReference()->getBeginLoc(),
       diag::warn_acc_confusing_routine_name);
  Diag(RoutineTarget->getBeginLoc(), diag::note_previous_decl) << ND;
}

void SemaOpenACC::ActOnVariableInit(VarDecl *VD, QualType InitType) {
  if (!VD || !getLangOpts().OpenACC || InitType.isNull())
    return;

  // To avoid double-diagnostic, just diagnose this during instantiation.  We'll
  // get 1 warning per instantiation, but this permits us to be more sensible
  // for cases where the lookup is confusing.
  if (VD->getLexicalDeclContext()->isDependentContext())
    return;

  const auto *RD = InitType->getAsCXXRecordDecl();
  // If this isn't a lambda, no sense in diagnosing.
  if (!RD || !RD->isLambda())
    return;

  CheckLastRoutineDeclNameConflict(VD);
}

void SemaOpenACC::ActOnFunctionDeclarator(FunctionDecl *FD) {
  if (!FD || !getLangOpts().OpenACC)
    return;
  CheckLastRoutineDeclNameConflict(FD);
}

bool SemaOpenACC::ActOnStartStmtDirective(
    OpenACCDirectiveKind K, SourceLocation StartLoc,
    ArrayRef<const OpenACCClause *> Clauses) {

  // Declaration directives an appear in a statement location, so call into that
  // function here.
  if (K == OpenACCDirectiveKind::Declare || K == OpenACCDirectiveKind::Routine)
    return ActOnStartDeclDirective(K, StartLoc, Clauses);

  SemaRef.DiscardCleanupsInEvaluationContext();
  SemaRef.PopExpressionEvaluationContext();

  // OpenACC 3.3 2.9.1:
  // Intervening code must not contain other OpenACC directives or calls to API
  // routines.
  //
  // ALL constructs are ill-formed if there is an active 'collapse'
  if (CollapseInfo.CurCollapseCount && *CollapseInfo.CurCollapseCount > 0) {
    Diag(StartLoc, diag::err_acc_invalid_in_loop)
        << /*OpenACC Construct*/ 0 << CollapseInfo.DirectiveKind
        << OpenACCClauseKind::Collapse << K;
    assert(CollapseInfo.ActiveCollapse && "Collapse count without object?");
    Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
         diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Collapse;
  }
  if (TileInfo.CurTileCount && *TileInfo.CurTileCount > 0) {
    Diag(StartLoc, diag::err_acc_invalid_in_loop)
        << /*OpenACC Construct*/ 0 << TileInfo.DirectiveKind
        << OpenACCClauseKind::Tile << K;
    assert(TileInfo.ActiveTile && "Tile count without object?");
    Diag(TileInfo.ActiveTile->getBeginLoc(), diag::note_acc_active_clause_here)
        << OpenACCClauseKind::Tile;
  }

  if (DiagnoseRequiredClauses(K, StartLoc, Clauses))
    return true;
  return diagnoseConstructAppertainment(*this, K, StartLoc, /*IsStmt=*/true);
}

StmtResult SemaOpenACC::ActOnEndStmtDirective(
    OpenACCDirectiveKind K, SourceLocation StartLoc, SourceLocation DirLoc,
    SourceLocation LParenLoc, SourceLocation MiscLoc, ArrayRef<Expr *> Exprs,
    OpenACCAtomicKind AtomicKind, SourceLocation RParenLoc,
    SourceLocation EndLoc, ArrayRef<OpenACCClause *> Clauses,
    StmtResult AssocStmt) {
  switch (K) {
  case OpenACCDirectiveKind::Invalid:
    return StmtError();
  case OpenACCDirectiveKind::Parallel:
  case OpenACCDirectiveKind::Serial:
  case OpenACCDirectiveKind::Kernels: {
    return OpenACCComputeConstruct::Create(
        getASTContext(), K, StartLoc, DirLoc, EndLoc, Clauses,
        AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::ParallelLoop:
  case OpenACCDirectiveKind::SerialLoop:
  case OpenACCDirectiveKind::KernelsLoop: {
    return OpenACCCombinedConstruct::Create(
        getASTContext(), K, StartLoc, DirLoc, EndLoc, Clauses,
        AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::Loop: {
    return OpenACCLoopConstruct::Create(
        getASTContext(), ActiveComputeConstructInfo.Kind, StartLoc, DirLoc,
        EndLoc, Clauses, AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::Data: {
    return OpenACCDataConstruct::Create(
        getASTContext(), StartLoc, DirLoc, EndLoc, Clauses,
        AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::EnterData: {
    return OpenACCEnterDataConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                             EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::ExitData: {
    return OpenACCExitDataConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                            EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::HostData: {
    return OpenACCHostDataConstruct::Create(
        getASTContext(), StartLoc, DirLoc, EndLoc, Clauses,
        AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::Wait: {
    return OpenACCWaitConstruct::Create(
        getASTContext(), StartLoc, DirLoc, LParenLoc, Exprs.front(), MiscLoc,
        Exprs.drop_front(), RParenLoc, EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::Init: {
    return OpenACCInitConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                        EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::Shutdown: {
    return OpenACCShutdownConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                            EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::Set: {
    return OpenACCSetConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                       EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::Update: {
    return OpenACCUpdateConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                          EndLoc, Clauses);
  }
  case OpenACCDirectiveKind::Atomic: {
    return OpenACCAtomicConstruct::Create(
        getASTContext(), StartLoc, DirLoc, AtomicKind, EndLoc, Clauses,
        AssocStmt.isUsable() ? AssocStmt.get() : nullptr);
  }
  case OpenACCDirectiveKind::Cache: {
    assert(Clauses.empty() && "Cache doesn't allow clauses");
    return OpenACCCacheConstruct::Create(getASTContext(), StartLoc, DirLoc,
                                         LParenLoc, MiscLoc, Exprs, RParenLoc,
                                         EndLoc);
  }
  case OpenACCDirectiveKind::Routine:
    llvm_unreachable("routine shouldn't handled here");
  case OpenACCDirectiveKind::Declare: {
    // Declare and routine arei declaration directives, but can be used here as
    // long as we wrap it in a DeclStmt.  So make sure we do that here.
    DeclGroupRef DR = ActOnEndDeclDirective(K, StartLoc, DirLoc, LParenLoc,
                                            RParenLoc, EndLoc, Clauses);

    return SemaRef.ActOnDeclStmt(DeclGroupPtrTy::make(DR), StartLoc, EndLoc);
  }
  }
  llvm_unreachable("Unhandled case in directive handling?");
}

StmtResult SemaOpenACC::ActOnAssociatedStmt(
    SourceLocation DirectiveLoc, OpenACCDirectiveKind K,
    OpenACCAtomicKind AtKind, ArrayRef<const OpenACCClause *> Clauses,
    StmtResult AssocStmt) {
  switch (K) {
  default:
    llvm_unreachable("Unimplemented associated statement application");
  case OpenACCDirectiveKind::EnterData:
  case OpenACCDirectiveKind::ExitData:
  case OpenACCDirectiveKind::Wait:
  case OpenACCDirectiveKind::Init:
  case OpenACCDirectiveKind::Shutdown:
  case OpenACCDirectiveKind::Set:
  case OpenACCDirectiveKind::Cache:
    llvm_unreachable(
        "these don't have associated statements, so shouldn't get here");
  case OpenACCDirectiveKind::Atomic:
    return CheckAtomicAssociatedStmt(DirectiveLoc, AtKind, AssocStmt);
  case OpenACCDirectiveKind::Parallel:
  case OpenACCDirectiveKind::Serial:
  case OpenACCDirectiveKind::Kernels:
  case OpenACCDirectiveKind::Data:
  case OpenACCDirectiveKind::HostData:
    // There really isn't any checking here that could happen. As long as we
    // have a statement to associate, this should be fine.
    // OpenACC 3.3 Section 6:
    // Structured Block: in C or C++, an executable statement, possibly
    // compound, with a single entry at the top and a single exit at the
    // bottom.
    // FIXME: Should we reject DeclStmt's here? The standard isn't clear, and
    // an interpretation of it is to allow this and treat the initializer as
    // the 'structured block'.
    return AssocStmt;
  case OpenACCDirectiveKind::Loop:
  case OpenACCDirectiveKind::ParallelLoop:
  case OpenACCDirectiveKind::SerialLoop:
  case OpenACCDirectiveKind::KernelsLoop:
    if (!AssocStmt.isUsable())
      return StmtError();

    if (!isa<CXXForRangeStmt, ForStmt>(AssocStmt.get())) {
      Diag(AssocStmt.get()->getBeginLoc(), diag::err_acc_loop_not_for_loop)
          << K;
      Diag(DirectiveLoc, diag::note_acc_construct_here) << K;
      return StmtError();
    }

    if (!CollapseInfo.CollapseDepthSatisfied || !TileInfo.TileDepthSatisfied) {
      if (!CollapseInfo.CollapseDepthSatisfied) {
        Diag(DirectiveLoc, diag::err_acc_insufficient_loops)
            << OpenACCClauseKind::Collapse;
        assert(CollapseInfo.ActiveCollapse && "Collapse count without object?");
        Diag(CollapseInfo.ActiveCollapse->getBeginLoc(),
             diag::note_acc_active_clause_here)
            << OpenACCClauseKind::Collapse;
      }

      if (!TileInfo.TileDepthSatisfied) {
        Diag(DirectiveLoc, diag::err_acc_insufficient_loops)
            << OpenACCClauseKind::Tile;
        assert(TileInfo.ActiveTile && "Collapse count without object?");
        Diag(TileInfo.ActiveTile->getBeginLoc(),
             diag::note_acc_active_clause_here)
            << OpenACCClauseKind::Tile;
      }
      return StmtError();
    }

    return AssocStmt.get();
  }
  llvm_unreachable("Invalid associated statement application");
}

namespace {

// Routine has some pretty complicated set of rules for how device_type
// interacts with 'gang', 'worker', 'vector', and 'seq'. Enforce  part of it
// here.
bool CheckValidRoutineGangWorkerVectorSeqClauses(
    SemaOpenACC &SemaRef, SourceLocation DirectiveLoc,
    ArrayRef<const OpenACCClause *> Clauses) {
  auto RequiredPred = llvm::IsaPred<OpenACCGangClause, OpenACCWorkerClause,
                                    OpenACCVectorClause, OpenACCSeqClause>;
  // The clause handling has assured us that there is no duplicates.  That is,
  // if there is 1 before a device_type, there are none after a device_type.
  // If not, there is at most 1 applying to each device_type.

  // What is left to legalize is that either:
  // 1- there is 1 before the first device_type.
  // 2- there is 1 AFTER each device_type.
  auto *FirstDeviceType =
      llvm::find_if(Clauses, llvm::IsaPred<OpenACCDeviceTypeClause>);

  // If there is 1 before the first device_type (or at all if no device_type),
  // we are legal.
  auto *ClauseItr =
      std::find_if(Clauses.begin(), FirstDeviceType, RequiredPred);

  if (ClauseItr != FirstDeviceType)
    return false;

  // If there IS no device_type, and no clause, diagnose.
  if (FirstDeviceType == Clauses.end())
    return SemaRef.Diag(DirectiveLoc, diag::err_acc_construct_one_clause_of)
           << OpenACCDirectiveKind::Routine
           << "'gang', 'seq', 'vector', or 'worker'";

  // Else, we have to check EACH device_type group. PrevDeviceType is the
  // device-type before the current group.
  auto *PrevDeviceType = FirstDeviceType;

  while (PrevDeviceType != Clauses.end()) {
    auto *NextDeviceType =
        std::find_if(std::next(PrevDeviceType), Clauses.end(),
                     llvm::IsaPred<OpenACCDeviceTypeClause>);

    ClauseItr = std::find_if(PrevDeviceType, NextDeviceType, RequiredPred);

    if (ClauseItr == NextDeviceType)
      return SemaRef.Diag((*PrevDeviceType)->getBeginLoc(),
                          diag::err_acc_clause_routine_one_of_in_region);

    PrevDeviceType = NextDeviceType;
  }

  return false;
}
} // namespace

bool SemaOpenACC::ActOnStartDeclDirective(
    OpenACCDirectiveKind K, SourceLocation StartLoc,
    ArrayRef<const OpenACCClause *> Clauses) {
  // OpenCC3.3 2.1 (line 889)
  // A program must not depend on the order of evaluation of expressions in
  // clause arguments or on any side effects of the evaluations.
  SemaRef.DiscardCleanupsInEvaluationContext();
  SemaRef.PopExpressionEvaluationContext();

  if (DiagnoseRequiredClauses(K, StartLoc, Clauses))
    return true;
  if (K == OpenACCDirectiveKind::Routine &&
      CheckValidRoutineGangWorkerVectorSeqClauses(*this, StartLoc, Clauses))
    return true;

  return diagnoseConstructAppertainment(*this, K, StartLoc, /*IsStmt=*/false);
}

DeclGroupRef SemaOpenACC::ActOnEndDeclDirective(
    OpenACCDirectiveKind K, SourceLocation StartLoc, SourceLocation DirLoc,
    SourceLocation LParenLoc, SourceLocation RParenLoc, SourceLocation EndLoc,
    ArrayRef<OpenACCClause *> Clauses) {
  switch (K) {
  default:
  case OpenACCDirectiveKind::Invalid:
    return DeclGroupRef{};
  case OpenACCDirectiveKind::Declare: {
    // OpenACC3.3 2.13: At least one clause must appear on a declare directive.
    if (Clauses.empty()) {
      Diag(EndLoc, diag::err_acc_declare_required_clauses);
      // No reason to add this to the AST, as we would just end up trying to
      // instantiate this, which would double-diagnose here, which we wouldn't
      // want to do.
      return DeclGroupRef{};
    }

    auto *DeclareDecl = OpenACCDeclareDecl::Create(
        getASTContext(), getCurContext(), StartLoc, DirLoc, EndLoc, Clauses);
    DeclareDecl->setAccess(AS_public);
    getCurContext()->addDecl(DeclareDecl);
    return DeclGroupRef{DeclareDecl};
  }
  case OpenACCDirectiveKind::Routine:
    llvm_unreachable("routine shouldn't be handled here");
  }
  llvm_unreachable("unhandled case in directive handling?");
}

namespace {
// Given the decl on the next line, figure out if it is one that is acceptable
// to `routine`, or looks like the sort of decl we should be diagnosing against.
FunctionDecl *LegalizeNextParsedDecl(Decl *D) {
  if (!D)
    return nullptr;

  // Functions are per-fact acceptable as-is.
  if (auto *FD = dyn_cast<FunctionDecl>(D))
    return FD;

  // Function templates are functions, so attach to the templated decl.
  if (auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
    return FTD->getTemplatedDecl();

  if (auto *FD = dyn_cast<FieldDecl>(D)) {
    auto *RD =
        FD->getType().isNull() ? nullptr : FD->getType()->getAsCXXRecordDecl();

    if (RD && RD->isGenericLambda())
      return RD->getDependentLambdaCallOperator()->getTemplatedDecl();
    if (RD && RD->isLambda())
      return RD->getLambdaCallOperator();
  }
  // VarDecl we can look at the init instead of the type of the variable, this
  // makes us more tolerant of the 'auto' deduced type.
  if (auto *VD = dyn_cast<VarDecl>(D)) {
    Expr *Init = VD->getInit();
    if (!Init || Init->getType().isNull())
      return nullptr;

    const auto *RD = Init->getType()->getAsCXXRecordDecl();
    if (RD && RD->isGenericLambda())
      return RD->getDependentLambdaCallOperator()->getTemplatedDecl();
    if (RD && RD->isLambda())
      return RD->getLambdaCallOperator();

    // FIXME: We could try harder in the case where this is a dependent thing
    // that ends up being a lambda (that is, the init is an unresolved lookup
    // expr), but we can't attach to the call/lookup expr. If we instead try to
    // attach to the VarDecl, when we go to instantiate it, attributes are
    // instantiated before the init, so we can't actually see the type at any
    // point where it would be relevant/able to be checked. We could perhaps do
    // some sort of 'after-init' instantiation/checking here, but that doesn't
    // seem valuable for a situation that other compilers don't handle.
  }
  return nullptr;
}

void CreateRoutineDeclAttr(SemaOpenACC &SemaRef, SourceLocation DirLoc,
                           ArrayRef<const OpenACCClause *> Clauses,
                           ValueDecl *AddTo) {
  OpenACCRoutineDeclAttr *A =
      OpenACCRoutineDeclAttr::Create(SemaRef.getASTContext(), DirLoc);
  A->Clauses.assign(Clauses.begin(), Clauses.end());
  AddTo->addAttr(A);
}
} // namespace

// Variant that adds attributes, because this is the unnamed case.
void SemaOpenACC::CheckRoutineDecl(SourceLocation DirLoc,
                                   ArrayRef<const OpenACCClause *> Clauses,
                                   Decl *NextParsedDecl) {

  FunctionDecl *NextParsedFDecl = LegalizeNextParsedDecl(NextParsedDecl);

  if (!NextParsedFDecl) {
    // If we don't have a valid 'next thing', just diagnose.
    SemaRef.Diag(DirLoc, diag::err_acc_decl_for_routine);
    return;
  }

  // OpenACC 3.3 2.15:
  // In C and C++, function static variables are not supported in functions to
  // which a routine directive applies.
  if (auto Itr = MagicStaticLocs.find(NextParsedFDecl->getCanonicalDecl());
      Itr != MagicStaticLocs.end()) {
    Diag(Itr->second, diag::err_acc_magic_static_in_routine);
    Diag(DirLoc, diag::note_acc_construct_here)
        << OpenACCDirectiveKind::Routine;

    return;
  }

  auto BindItr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCBindClause>);
  for (auto *A : NextParsedFDecl->attrs()) {
    // OpenACC 3.3 2.15:
    // If a procedure has a bind clause on both the declaration and definition
    // than they both must bind to the same name.
    if (auto *RA = dyn_cast<OpenACCRoutineDeclAttr>(A)) {
      auto OtherBindItr =
          llvm::find_if(RA->Clauses, llvm::IsaPred<OpenACCBindClause>);
      if (OtherBindItr != RA->Clauses.end() &&
          (*cast<OpenACCBindClause>(*BindItr)) !=
              (*cast<OpenACCBindClause>(*OtherBindItr))) {
        Diag((*BindItr)->getBeginLoc(), diag::err_acc_duplicate_unnamed_bind);
        Diag((*OtherBindItr)->getEndLoc(), diag::note_acc_previous_clause_here)
            << (*BindItr)->getClauseKind();
        return;
      }
    }

    // OpenACC 3.3 2.15:
    // A bind clause may not bind to a routine name that has a visible bind
    // clause.
    // We take the combo of these two 2.15 restrictions to mean that the
    // 'declaration'/'definition' quote is an exception to this. So we're going
    // to disallow mixing of the two types entirely.
    if (auto *RA = dyn_cast<OpenACCRoutineAnnotAttr>(A);
        RA && RA->getRange().getEnd().isValid()) {
      Diag((*BindItr)->getBeginLoc(), diag::err_acc_duplicate_bind);
      Diag(RA->getRange().getEnd(), diag::note_acc_previous_clause_here)
          << "bind";
      return;
    }
  }

  CreateRoutineDeclAttr(*this, DirLoc, Clauses, NextParsedFDecl);
}

// Variant that adds a decl, because this is the named case.
OpenACCRoutineDecl *SemaOpenACC::CheckRoutineDecl(
    SourceLocation StartLoc, SourceLocation DirLoc, SourceLocation LParenLoc,
    Expr *FuncRef, SourceLocation RParenLoc,
    ArrayRef<const OpenACCClause *> Clauses, SourceLocation EndLoc) {
  assert(LParenLoc.isValid());

  if (FunctionDecl *FD = getFunctionFromRoutineName(FuncRef)) {
    // OpenACC 3.3 2.15:
    // In C and C++, function static variables are not supported in functions to
    // which a routine directive applies.
    if (auto Itr = MagicStaticLocs.find(FD->getCanonicalDecl());
        Itr != MagicStaticLocs.end()) {
      Diag(Itr->second, diag::err_acc_magic_static_in_routine);
      Diag(DirLoc, diag::note_acc_construct_here)
          << OpenACCDirectiveKind::Routine;

      return nullptr;
    }

    // OpenACC 3.3 2.15:
    // A bind clause may not bind to a routine name that has a visible bind
    // clause.
    auto BindItr = llvm::find_if(Clauses, llvm::IsaPred<OpenACCBindClause>);
    SourceLocation BindLoc;
    if (BindItr != Clauses.end()) {
      BindLoc = (*BindItr)->getBeginLoc();
      // Since this is adding a 'named' routine, we aren't allowed to combine
      // with ANY other visible bind clause. Error if we see either.

      for (auto *A : FD->attrs()) {
        if (auto *RA = dyn_cast<OpenACCRoutineDeclAttr>(A)) {
          auto OtherBindItr =
              llvm::find_if(RA->Clauses, llvm::IsaPred<OpenACCBindClause>);
          if (OtherBindItr != RA->Clauses.end()) {
            Diag((*BindItr)->getBeginLoc(), diag::err_acc_duplicate_bind);
            Diag((*OtherBindItr)->getEndLoc(),
                 diag::note_acc_previous_clause_here)
                << (*BindItr)->getClauseKind();
            return nullptr;
          }
        }

        if (auto *RA = dyn_cast<OpenACCRoutineAnnotAttr>(A);
            RA && RA->getRange().getEnd().isValid()) {
          Diag((*BindItr)->getBeginLoc(), diag::err_acc_duplicate_bind);
          Diag(RA->getRange().getEnd(), diag::note_acc_previous_clause_here)
              << (*BindItr)->getClauseKind();
          return nullptr;
        }
      }
    }

    // Set the end-range to the 'bind' clause here, so we can look it up
    // later.
    auto *RAA = OpenACCRoutineAnnotAttr::CreateImplicit(getASTContext(),
                                                        {DirLoc, BindLoc});
    FD->addAttr(RAA);
    // In case we are referencing not the 'latest' version, make sure we add
    // the attribute to all declarations.
    while (FD != FD->getMostRecentDecl()) {
      FD = FD->getMostRecentDecl();
      FD->addAttr(RAA);
    }
  }

  LastRoutineDecl = OpenACCRoutineDecl::Create(
      getASTContext(), getCurContext(), StartLoc, DirLoc, LParenLoc, FuncRef,
      RParenLoc, EndLoc, Clauses);
  LastRoutineDecl->setAccess(AS_public);
  getCurContext()->addDecl(LastRoutineDecl);

  return LastRoutineDecl;
}

DeclGroupRef SemaOpenACC::ActOnEndRoutineDeclDirective(
    SourceLocation StartLoc, SourceLocation DirLoc, SourceLocation LParenLoc,
    Expr *ReferencedFunc, SourceLocation RParenLoc,
    ArrayRef<const OpenACCClause *> Clauses, SourceLocation EndLoc,
    DeclGroupPtrTy NextDecl) {
  assert((!ReferencedFunc || !NextDecl) &&
         "Only one of these should be filled");

  if (LParenLoc.isInvalid()) {
    Decl *NextLineDecl = nullptr;
    if (NextDecl && NextDecl.get().isSingleDecl())
      NextLineDecl = NextDecl.get().getSingleDecl();

    CheckRoutineDecl(DirLoc, Clauses, NextLineDecl);

    return NextDecl.get();
  }

  return DeclGroupRef{CheckRoutineDecl(
      StartLoc, DirLoc, LParenLoc, ReferencedFunc, RParenLoc, Clauses, EndLoc)};
}

StmtResult SemaOpenACC::ActOnEndRoutineStmtDirective(
    SourceLocation StartLoc, SourceLocation DirLoc, SourceLocation LParenLoc,
    Expr *ReferencedFunc, SourceLocation RParenLoc,
    ArrayRef<const OpenACCClause *> Clauses, SourceLocation EndLoc,
    Stmt *NextStmt) {
  assert((!ReferencedFunc || !NextStmt) &&
         "Only one of these should be filled");

  if (LParenLoc.isInvalid()) {
    Decl *NextLineDecl = nullptr;
    if (NextStmt)
      if (DeclStmt *DS = dyn_cast<DeclStmt>(NextStmt); DS && DS->isSingleDecl())
        NextLineDecl = DS->getSingleDecl();

    CheckRoutineDecl(DirLoc, Clauses, NextLineDecl);
    return NextStmt;
  }

  DeclGroupRef DR{CheckRoutineDecl(StartLoc, DirLoc, LParenLoc, ReferencedFunc,
                                   RParenLoc, Clauses, EndLoc)};
  return SemaRef.ActOnDeclStmt(DeclGroupPtrTy::make(DR), StartLoc, EndLoc);
}

OpenACCRoutineDeclAttr *
SemaOpenACC::mergeRoutineDeclAttr(const OpenACCRoutineDeclAttr &Old) {
  OpenACCRoutineDeclAttr *New =
      OpenACCRoutineDeclAttr::Create(getASTContext(), Old.getLocation());
  // We should jsut be able to copy these, there isn't really any
  // merging/inheriting we have to do, so no worry about doing a deep copy.
  New->Clauses = Old.Clauses;
  return New;
}
ExprResult
SemaOpenACC::BuildOpenACCAsteriskSizeExpr(SourceLocation AsteriskLoc) {
  return OpenACCAsteriskSizeExpr::Create(getASTContext(), AsteriskLoc);
}

ExprResult
SemaOpenACC::ActOnOpenACCAsteriskSizeExpr(SourceLocation AsteriskLoc) {
  return BuildOpenACCAsteriskSizeExpr(AsteriskLoc);
}