//===--- SemaStmtAttr.cpp - Statement Attribute Handling ------------------===//

//

// 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 file implements stmt-related attribute processing.

//

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

#include "clang/AST/EvaluatedExprVisitor.h"

#include "clang/Sema/SemaInternal.h"

#include "clang/AST/ASTContext.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Sema/DelayedDiagnostic.h"

#include "clang/Sema/Lookup.h"

#include "clang/Sema/ScopeInfo.h"

#include "llvm/ADT/StringExtras.h"

using namespace clang;

using namespace sema;

static Attr *handleFallThroughAttr(Sema &S, Stmt *St, const ParsedAttr &A,

                                   SourceRange Range) {

  FallThroughAttr Attr(S.Context, A);

  if (!isa<NullStmt>(St)) {

    S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_wrong_target)

        << Attr.getSpelling() << St->getBeginLoc();

    if (isa<SwitchCase>(St)) {

      SourceLocation L = S.getLocForEndOfToken(Range.getEnd());

      S.Diag(L, diag::note_fallthrough_insert_semi_fixit)

          << FixItHint::CreateInsertion(L, ";");

    }

    return nullptr;

  }

  auto *FnScope = S.getCurFunction();

  if (FnScope->SwitchStack.empty()) {

    S.Diag(A.getRange().getBegin(), diag::err_fallthrough_attr_outside_switch);

    return nullptr;

  }

  // If this is spelled as the standard C++17 attribute, but not in C++17, warn

  // about using it as an extension.

  if (!S.getLangOpts().CPlusPlus17 && 
A.isCXX11Attribute()927
 &&

      !A.getScopeName())

    S.Diag(A.getLoc(), diag::ext_cxx17_attr) << A;

  FnScope->setHasFallthroughStmt();

  return ::new (S.Context) FallThroughAttr(S.Context, A);

}

static Attr *handleSuppressAttr(Sema &S, Stmt *St, const ParsedAttr &A,

                                SourceRange Range) {

  if (A.getNumArgs() < 1) {

    S.Diag(A.getLoc(), diag::err_attribute_too_few_arguments) << A << 1;

    return nullptr;

  }

  std::vector<StringRef> DiagnosticIdentifiers;

  for (unsigned I = 0, E = A.getNumArgs(); I != E; 
++I6
) {

    StringRef RuleName;

    if (!S.checkStringLiteralArgumentAttr(A, I, RuleName, nullptr))

      return nullptr;

    // FIXME: Warn if the rule name is unknown. This is tricky because only

    // clang-tidy knows about available rules.

    DiagnosticIdentifiers.push_back(RuleName);

  }

  return ::new (S.Context) SuppressAttr(

      S.Context, A, DiagnosticIdentifiers.data(), DiagnosticIdentifiers.size());

}

static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,

                                SourceRange) {

  IdentifierLoc *PragmaNameLoc = A.getArgAsIdent(0);

  IdentifierLoc *OptionLoc = A.getArgAsIdent(1);

  IdentifierLoc *StateLoc = A.getArgAsIdent(2);

  Expr *ValueExpr = A.getArgAsExpr(3);

  StringRef PragmaName =

      llvm::StringSwitch<StringRef>(PragmaNameLoc->Ident->getName())

          .Cases("unroll", "nounroll", "unroll_and_jam", "nounroll_and_jam",

                 PragmaNameLoc->Ident->getName())

          .Default("clang loop");

  if (St->getStmtClass() != Stmt::DoStmtClass &&

      St->getStmtClass() != Stmt::ForStmtClass &&

      St->getStmtClass() != Stmt::CXXForRangeStmtClass &&

      St->getStmtClass() != Stmt::WhileStmtClass) {

    std::string Pragma = "#pragma " + std::string(PragmaName);

    S.Diag(St->getBeginLoc(), diag::err_pragma_loop_precedes_nonloop) << Pragma;

    return nullptr;

  }

  LoopHintAttr::OptionType Option;

  LoopHintAttr::LoopHintState State;

  auto SetHints = [&Option, &State](LoopHintAttr::OptionType O,

                                    LoopHintAttr::LoopHintState S) {

    Option = O;

    State = S;

  };

  if (PragmaName == "nounroll") {

    SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);

  } else if (PragmaName == "unroll") {

    // #pragma unroll N

    if (ValueExpr)

      SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);

    else

      SetHints(LoopHintAttr::Unroll, LoopHintAttr::Enable);

  } else if (PragmaName == "nounroll_and_jam") {

    SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Disable);

  } else if (PragmaName == "unroll_and_jam") {

    // #pragma unroll_and_jam N

    if (ValueExpr)

      SetHints(LoopHintAttr::UnrollAndJamCount, LoopHintAttr::Numeric);

    else

      SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Enable);

  } else {

    // #pragma clang loop ...

    assert(OptionLoc && OptionLoc->Ident &&

           "Attribute must have valid option info.");

    Option = llvm::StringSwitch<LoopHintAttr::OptionType>(

                 OptionLoc->Ident->getName())

                 .Case("vectorize", LoopHintAttr::Vectorize)

                 .Case("vectorize_width", LoopHintAttr::VectorizeWidth)

                 .Case("interleave", LoopHintAttr::Interleave)

                 .Case("vectorize_predicate", LoopHintAttr::VectorizePredicate)

                 .Case("interleave_count", LoopHintAttr::InterleaveCount)

                 .Case("unroll", LoopHintAttr::Unroll)

                 .Case("unroll_count", LoopHintAttr::UnrollCount)

                 .Case("pipeline", LoopHintAttr::PipelineDisabled)

                 .Case("pipeline_initiation_interval",

                       LoopHintAttr::PipelineInitiationInterval)

                 .Case("distribute", LoopHintAttr::Distribute)

                 .Default(LoopHintAttr::Vectorize);

    if (Option == LoopHintAttr::VectorizeWidth ||

        Option == LoopHintAttr::InterleaveCount ||

        Option == LoopHintAttr::UnrollCount ||

        Option == LoopHintAttr::PipelineInitiationInterval) {

      assert(ValueExpr && "Attribute must have a valid value expression.");

      if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))

        return nullptr;

      State = LoopHintAttr::Numeric;

    } else if (Option == LoopHintAttr::Vectorize ||

               Option == LoopHintAttr::Interleave ||

               Option == LoopHintAttr::VectorizePredicate ||

               Option == LoopHintAttr::Unroll ||

               Option == LoopHintAttr::Distribute ||

               
Option == LoopHintAttr::PipelineDisabled4
) {

      assert(StateLoc && StateLoc->Ident && "Loop hint must have an argument");

      if (StateLoc->Ident->isStr("disable"))

        State = LoopHintAttr::Disable;

      else if (StateLoc->Ident->isStr("assume_safety"))

        State = LoopHintAttr::AssumeSafety;

      else if (StateLoc->Ident->isStr("full"))

        State = LoopHintAttr::Full;

      else if (StateLoc->Ident->isStr("enable"))

        State = LoopHintAttr::Enable;

      else

        llvm_unreachable("bad loop hint argument");

    } else

      llvm_unreachable("bad loop hint");

  }

  return LoopHintAttr::CreateImplicit(S.Context, Option, State, ValueExpr, A);

}

namespace {

class CallExprFinder : public ConstEvaluatedExprVisitor<CallExprFinder> {

  bool FoundCallExpr = false;

public:

  typedef ConstEvaluatedExprVisitor<CallExprFinder> Inherited;

  CallExprFinder(Sema &S, const Stmt *St) : Inherited(S.Context) { Visit(St); }

  bool foundCallExpr() { return FoundCallExpr; }

  void VisitCallExpr(const CallExpr *E) { FoundCallExpr = true; }

  void VisitAsmStmt(const AsmStmt *S) { FoundCallExpr = true; }

  void Visit(const Stmt *St) {

    if (!St)

      return;

    ConstEvaluatedExprVisitor<CallExprFinder>::Visit(St);

  }

};

} // namespace

static Attr *handleNoMergeAttr(Sema &S, Stmt *St, const ParsedAttr &A,

                               SourceRange Range) {

  NoMergeAttr NMA(S.Context, A);

  if (S.CheckAttrNoArgs(A))

    return nullptr;

  CallExprFinder CEF(S, St);

  if (!CEF.foundCallExpr()) {

    S.Diag(St->getBeginLoc(), diag::warn_nomerge_attribute_ignored_in_stmt)

        << NMA.getSpelling();

    return nullptr;

  }

  return ::new (S.Context) NoMergeAttr(S.Context, A);

}

static Attr *handleLikely(Sema &S, Stmt *St, const ParsedAttr &A,

                          SourceRange Range) {

  if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && 
!A.getScopeName()17
)

    S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;

  return ::new (S.Context) LikelyAttr(S.Context, A);

}

static Attr *handleUnlikely(Sema &S, Stmt *St, const ParsedAttr &A,

                            SourceRange Range) {

  if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && 
!A.getScopeName()46
)

    S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << Range;

  return ::new (S.Context) UnlikelyAttr(S.Context, A);

}

static void

CheckForIncompatibleAttributes(Sema &S,

                               const SmallVectorImpl<const Attr *> &Attrs) {

  // There are 6 categories of loop hints attributes: vectorize, interleave,

  // unroll, unroll_and_jam, pipeline and distribute. Except for distribute they

  // come in two variants: a state form and a numeric form.  The state form

  // selectively defaults/enables/disables the transformation for the loop

  // (for unroll, default indicates full unrolling rather than enabling the

  // transformation). The numeric form form provides an integer hint (for

  // example, unroll count) to the transformer. The following array accumulates

  // the hints encountered while iterating through the attributes to check for

  // compatibility.

  struct {

    const LoopHintAttr *StateAttr;

    const LoopHintAttr *NumericAttr;

  } HintAttrs[] = {{nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},

                   {nullptr, nullptr}, {nullptr, nullptr}, {nullptr, nullptr},

                   {nullptr, nullptr}};

  for (const auto *I : Attrs) {

    const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(I);

    // Skip non loop hint attributes

    if (!LH)

      continue;

    LoopHintAttr::OptionType Option = LH->getOption();

    enum {

      Vectorize,

      Interleave,

      Unroll,

      UnrollAndJam,

      Distribute,

      Pipeline,

      VectorizePredicate

    } Category;

    switch (Option) {

    case LoopHintAttr::Vectorize:

    case LoopHintAttr::VectorizeWidth:

      Category = Vectorize;

      break;

    case LoopHintAttr::Interleave:

    case LoopHintAttr::InterleaveCount:

      Category = Interleave;

      break;

    case LoopHintAttr::Unroll:

    case LoopHintAttr::UnrollCount:

      Category = Unroll;

      break;

    case LoopHintAttr::UnrollAndJam:

    case LoopHintAttr::UnrollAndJamCount:

      Category = UnrollAndJam;

      break;

    case LoopHintAttr::Distribute:

      // Perform the check for duplicated 'distribute' hints.

      Category = Distribute;

      break;

    case LoopHintAttr::PipelineDisabled:

    case LoopHintAttr::PipelineInitiationInterval:

      Category = Pipeline;

      break;

    case LoopHintAttr::VectorizePredicate:

      Category = VectorizePredicate;

      break;

    };

    assert(Category < sizeof(HintAttrs) / sizeof(HintAttrs[0]));

    auto &CategoryState = HintAttrs[Category];

    const LoopHintAttr *PrevAttr;

    if (Option == LoopHintAttr::Vectorize ||

        Option == LoopHintAttr::Interleave || 
Option == LoopHintAttr::Unroll213
 ||

        Option == LoopHintAttr::UnrollAndJam ||

        Option == LoopHintAttr::VectorizePredicate ||

        Option == LoopHintAttr::PipelineDisabled ||

        
Option == LoopHintAttr::Distribute140
) {

      // Enable|Disable|AssumeSafety hint.  For example, vectorize(enable).

      PrevAttr = CategoryState.StateAttr;

      CategoryState.StateAttr = LH;

    } else {

      // Numeric hint.  For example, vectorize_width(8).

      PrevAttr = CategoryState.NumericAttr;

      CategoryState.NumericAttr = LH;

    }

    PrintingPolicy Policy(S.Context.getLangOpts());

    SourceLocation OptionLoc = LH->getRange().getBegin();

    if (PrevAttr)

      // Cannot specify same type of attribute twice.

      S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)

          << /*Duplicate=*/true << PrevAttr->getDiagnosticName(Policy)

          << LH->getDiagnosticName(Policy);

    if (CategoryState.StateAttr && 
CategoryState.NumericAttr172
 &&

        (Category == Unroll || 
Category == UnrollAndJam10
 ||

         
CategoryState.StateAttr->getState() == LoopHintAttr::Disable9
)) {

      // Disable hints are not compatible with numeric hints of the same

      // category.  As a special case, numeric unroll hints are also not

      // compatible with enable or full form of the unroll pragma because these

      // directives indicate full unrolling.

      S.Diag(OptionLoc, diag::err_pragma_loop_compatibility)

          << /*Duplicate=*/false

          << CategoryState.StateAttr->getDiagnosticName(Policy)

          << CategoryState.NumericAttr->getDiagnosticName(Policy);

    }

  }

  // C++20 [dcl.attr.likelihood]p1 The attribute-token likely shall not appear

  // in an attribute-specifier-seq that contains the attribute-token unlikely.

  const LikelyAttr *Likely = nullptr;

  const UnlikelyAttr *Unlikely = nullptr;

  for (const auto *I : Attrs) {

    if (const auto *Attr = dyn_cast<LikelyAttr>(I)) {

      if (Unlikely) {

        S.Diag(Attr->getLocation(), diag::err_attributes_are_not_compatible)

            << Attr << Unlikely << Attr->getRange();

        S.Diag(Unlikely->getLocation(), diag::note_conflicting_attribute)

            << Unlikely->getRange();

        return;

      }

      Likely = Attr;

    } else if (const auto *Attr = dyn_cast<UnlikelyAttr>(I)) {

      if (Likely) {

        S.Diag(Attr->getLocation(), diag::err_attributes_are_not_compatible)

            << Attr << Likely << Attr->getRange();

        S.Diag(Likely->getLocation(), diag::note_conflicting_attribute)

            << Likely->getRange();

        return;

      }

      Unlikely = Attr;

    }

  }

}

static Attr *handleOpenCLUnrollHint(Sema &S, Stmt *St, const ParsedAttr &A,

                                    SourceRange Range) {

  // Although the feature was introduced only in OpenCL C v2.0 s6.11.5, it's

  // useful for OpenCL 1.x too and doesn't require HW support.

  // opencl_unroll_hint can have 0 arguments (compiler

  // determines unrolling factor) or 1 argument (the unroll factor provided

  // by the user).

  unsigned NumArgs = A.getNumArgs();

  if (NumArgs > 1) {

    S.Diag(A.getLoc(), diag::err_attribute_too_many_arguments) << A << 1;

    return nullptr;

  }

  unsigned UnrollFactor = 0;

  if (NumArgs == 1) {

    Expr *E = A.getArgAsExpr(0);

    Optional<llvm::APSInt> ArgVal;

    if (!(ArgVal = E->getIntegerConstantExpr(S.Context))) {

      S.Diag(A.getLoc(), diag::err_attribute_argument_type)

          << A << AANT_ArgumentIntegerConstant << E->getSourceRange();

      return nullptr;

    }

    int Val = ArgVal->getSExtValue();

    if (Val <= 0) {

      S.Diag(A.getRange().getBegin(),

             diag::err_attribute_requires_positive_integer)

          << A << /* positive */ 0;

      return nullptr;

    }

    UnrollFactor = Val;

  }

  return OpenCLUnrollHintAttr::CreateImplicit(S.Context, UnrollFactor);

}

static Attr *ProcessStmtAttribute(Sema &S, Stmt *St, const ParsedAttr &A,

                                  SourceRange Range) {

  switch (A.getKind()) {

  case ParsedAttr::UnknownAttribute:

    S.Diag(A.getLoc(), A.isDeclspecAttribute()

                           ? (unsigned)diag::warn_unhandled_ms_attribute_ignored

                           : (unsigned)diag::warn_unknown_attribute_ignored)

        << A;

    return nullptr;

  case ParsedAttr::AT_FallThrough:

    return handleFallThroughAttr(S, St, A, Range);

  case ParsedAttr::AT_LoopHint:

    return handleLoopHintAttr(S, St, A, Range);

  case ParsedAttr::AT_OpenCLUnrollHint:

    return handleOpenCLUnrollHint(S, St, A, Range);

  case ParsedAttr::AT_Suppress:

    return handleSuppressAttr(S, St, A, Range);

  case ParsedAttr::AT_NoMerge:

    return handleNoMergeAttr(S, St, A, Range);

  case ParsedAttr::AT_Likely:

    return handleLikely(S, St, A, Range);

  case ParsedAttr::AT_Unlikely:

    return handleUnlikely(S, St, A, Range);

  default:

    // if we're here, then we parsed a known attribute, but didn't recognize

    // it as a statement attribute => it is declaration attribute

    S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)

        << A << St->getBeginLoc();

    return nullptr;

  }

}

StmtResult Sema::ProcessStmtAttributes(Stmt *S,

                                       const ParsedAttributesView &AttrList,

                                       SourceRange Range) {

  SmallVector<const Attr*, 8> Attrs;

  for (const ParsedAttr &AL : AttrList) {

    if (Attr *a = ProcessStmtAttribute(*this, S, AL, Range))

      Attrs.push_back(a);

  }

  CheckForIncompatibleAttributes(*this, Attrs);

  if (Attrs.empty())

    return S;

  return ActOnAttributedStmt(Range.getBegin(), Attrs, S);

}