//===- SemaSYCL.cpp - Semantic Analysis for SYCL 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

//

//===----------------------------------------------------------------------===//

// This implements Semantic Analysis for SYCL constructs.

//===----------------------------------------------------------------------===//

#include "clang/AST/Mangle.h"

#include "clang/Sema/Sema.h"

#include "clang/Sema/SemaDiagnostic.h"

using namespace clang;

// -----------------------------------------------------------------------------

// SYCL device specific diagnostics implementation

// -----------------------------------------------------------------------------

Sema::SemaDiagnosticBuilder Sema::SYCLDiagIfDeviceCode(SourceLocation Loc,

                                                       unsigned DiagID) {

  assert(getLangOpts().SYCLIsDevice &&

         "Should only be called during SYCL compilation");

  FunctionDecl *FD = dyn_cast<FunctionDecl>(getCurLexicalContext());

  SemaDiagnosticBuilder::Kind DiagKind = [this, FD] {

    if (!FD)

      return SemaDiagnosticBuilder::K_Nop;

    if (getEmissionStatus(FD) == Sema::FunctionEmissionStatus::Emitted)

      return SemaDiagnosticBuilder::K_ImmediateWithCallStack;

    return SemaDiagnosticBuilder::K_Deferred;

  }();

  return SemaDiagnosticBuilder(DiagKind, Loc, DiagID, FD, *this);

}

static bool isZeroSizedArray(Sema &SemaRef, QualType Ty) {

  if (const auto *CAT = SemaRef.getASTContext().getAsConstantArrayType(Ty))

    return CAT->getSize() == 0;

  return false;

}

void Sema::deepTypeCheckForSYCLDevice(SourceLocation UsedAt,

                                      llvm::DenseSet<QualType> Visited,

                                      ValueDecl *DeclToCheck) {

  assert(getLangOpts().SYCLIsDevice &&

         "Should only be called during SYCL compilation");

  // Emit notes only for the first discovered declaration of unsupported type

  // to avoid mess of notes. This flag is to track that error already happened.

  bool NeedToEmitNotes = true;

  auto Check = [&](QualType TypeToCheck, const ValueDecl *D) {

    bool ErrorFound = false;

    if (isZeroSizedArray(*this, TypeToCheck)) {

      SYCLDiagIfDeviceCode(UsedAt, diag::err_typecheck_zero_array_size) << 1;

      ErrorFound = true;

    }

    // Checks for other types can also be done here.

    if (ErrorFound) {

      if (NeedToEmitNotes) {

        if (auto *FD = dyn_cast<FieldDecl>(D))

          SYCLDiagIfDeviceCode(FD->getLocation(),

                               diag::note_illegal_field_declared_here)

              << FD->getType()->isPointerType() << FD->getType();

        else

          SYCLDiagIfDeviceCode(D->getLocation(), diag::note_declared_at);

      }

    }

    return ErrorFound;

  };

  // In case we have a Record used do the DFS for a bad field.

  SmallVector<const ValueDecl *, 4> StackForRecursion;

  StackForRecursion.push_back(DeclToCheck);

  // While doing DFS save how we get there to emit a nice set of notes.

  SmallVector<const FieldDecl *, 4> History;

  History.push_back(nullptr);

  do {

    const ValueDecl *Next = StackForRecursion.pop_back_val();

    if (!Next) {

      assert(!History.empty());

      // Found a marker, we have gone up a level.

      History.pop_back();

      continue;

    }

    QualType NextTy = Next->getType();

    if (!Visited.insert(NextTy).second)

      continue;

    auto EmitHistory = [&]() {

      // The first element is always nullptr.

      for (uint64_t Index = 1; Index < History.size(); ++Index) {

        SYCLDiagIfDeviceCode(History[Index]->getLocation(),

                             diag::note_within_field_of_type)

            << History[Index]->getType();

      }

    };

    if (Check(NextTy, Next)) {

      if (NeedToEmitNotes)

        EmitHistory();

      NeedToEmitNotes = false;

    }

    // In case pointer/array/reference type is met get pointee type, then

    // proceed with that type.

    while (NextTy->isAnyPointerType() || NextTy->isArrayType() ||

           NextTy->isReferenceType()) {

      if (NextTy->isArrayType())

        NextTy = QualType{NextTy->getArrayElementTypeNoTypeQual(), 0};

      else

        NextTy = NextTy->getPointeeType();

      if (Check(NextTy, Next)) {

        if (NeedToEmitNotes)

          EmitHistory();

        NeedToEmitNotes = false;

      }

    }

    if (const auto *RecDecl = NextTy->getAsRecordDecl()) {

      if (auto *NextFD = dyn_cast<FieldDecl>(Next))

        History.push_back(NextFD);

      // When nullptr is discovered, this means we've gone back up a level, so

      // the history should be cleaned.

      StackForRecursion.push_back(nullptr);

      llvm::copy(RecDecl->fields(), std::back_inserter(StackForRecursion));

    }

  } while (!StackForRecursion.empty());

}