//===--- LayoutOverrideSource.cpp --Override Record Layouts ---------------===//

//

// 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

//

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

#include "clang/Frontend/LayoutOverrideSource.h"

#include "clang/AST/Decl.h"

#include "clang/Basic/CharInfo.h"

#include "llvm/Support/raw_ostream.h"

#include <fstream>

#include <string>

using namespace clang;

/// Parse a simple identifier.

static std::string parseName(StringRef S) {

  if (S.empty() || !isAsciiIdentifierStart(S[0]))

    return "";

  unsigned Offset = 1;

  while (Offset < S.size() && 
isAsciiIdentifierContinue(S[Offset])51
)

    ++Offset;

  return S.substr(0, Offset).str();

}

LayoutOverrideSource::LayoutOverrideSource(StringRef Filename) {

  std::ifstream Input(Filename.str().c_str());

  if (!Input.is_open())

    return;

  // Parse the output of -fdump-record-layouts.

  std::string CurrentType;

  Layout CurrentLayout;

  bool ExpectingType = false;

  while (Input.good()) {

    std::string Line;

    getline(Input, Line);

    StringRef LineStr(Line);

    // Determine whether the following line will start a

    if (LineStr.contains("*** Dumping AST Record Layout")) {

      // Flush the last type/layout, if there is one.

      if (!CurrentType.empty())

        Layouts[CurrentType] = CurrentLayout;

      CurrentLayout = Layout();

      ExpectingType = true;

      continue;

    }

    // If we're expecting a type, grab it.

    if (ExpectingType) {

      ExpectingType = false;

      StringRef::size_type Pos;

      if ((Pos = LineStr.find("struct ")) != StringRef::npos)

        LineStr = LineStr.substr(Pos + strlen("struct "));

      else if ((Pos = LineStr.find("class ")) != StringRef::npos)

        LineStr = LineStr.substr(Pos + strlen("class "));

      else if ((Pos = LineStr.find("union ")) != StringRef::npos)

        LineStr = LineStr.substr(Pos + strlen("union "));

      else

        continue;

      // Find the name of the type.

      CurrentType = parseName(LineStr);

      CurrentLayout = Layout();

      continue;

    }

    // Check for the size of the type.

    StringRef::size_type Pos = LineStr.find(" Size:");

    if (Pos != StringRef::npos) {

      // Skip past the " Size:" prefix.

      LineStr = LineStr.substr(Pos + strlen(" Size:"));

      unsigned long long Size = 0;

      (void)LineStr.getAsInteger(10, Size);

      CurrentLayout.Size = Size;

      continue;

    }

    // Check for the alignment of the type.

    Pos = LineStr.find("Alignment:");

    if (Pos != StringRef::npos) {

      // Skip past the "Alignment:" prefix.

      LineStr = LineStr.substr(Pos + strlen("Alignment:"));

      unsigned long long Alignment = 0;

      (void)LineStr.getAsInteger(10, Alignment);

      CurrentLayout.Align = Alignment;

      continue;

    }

    // Check for the size/alignment of the type.

    Pos = LineStr.find("sizeof=");

    if (Pos != StringRef::npos) {

      /* Skip past the sizeof= prefix. */

      LineStr = LineStr.substr(Pos + strlen("sizeof="));

      // Parse size.

      unsigned long long Size = 0;

      (void)LineStr.getAsInteger(10, Size);

      CurrentLayout.Size = Size;

      Pos = LineStr.find("align=");

      if (Pos != StringRef::npos) {

        /* Skip past the align= prefix. */

        LineStr = LineStr.substr(Pos + strlen("align="));

        // Parse alignment.

        unsigned long long Alignment = 0;

        (void)LineStr.getAsInteger(10, Alignment);

        CurrentLayout.Align = Alignment;

      }

      continue;

    }

    // Check for the field offsets of the type.

    Pos = LineStr.find("FieldOffsets: [");

    if (Pos == StringRef::npos)

      continue;

    LineStr = LineStr.substr(Pos + strlen("FieldOffsets: ["));

    while (!LineStr.empty() && isDigit(LineStr[0])) {

      // Parse this offset.

      unsigned Idx = 1;

      while (Idx < LineStr.size() && isDigit(LineStr[Idx]))

        ++Idx;

      unsigned long long Offset = 0;

      (void)LineStr.substr(0, Idx).getAsInteger(10, Offset);

      CurrentLayout.FieldOffsets.push_back(Offset);

      // Skip over this offset, the following comma, and any spaces.

      LineStr = LineStr.substr(Idx + 1);

      while (!LineStr.empty() && isWhitespace(LineStr[0]))

        LineStr = LineStr.substr(1);

    }

  }

  // Flush the last type/layout, if there is one.

  if (!CurrentType.empty())

    Layouts[CurrentType] = CurrentLayout;

}

bool

LayoutOverrideSource::layoutRecordType(const RecordDecl *Record,

  uint64_t &Size, uint64_t &Alignment,

  llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,

  llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,

  llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets)

{

  // We can't override unnamed declarations.

  if (!Record->getIdentifier())

    return false;

  // Check whether we have a layout for this record.

  llvm::StringMap<Layout>::iterator Known = Layouts.find(Record->getName());

  if (Known == Layouts.end())

    return false;

  // Provide field layouts.

  unsigned NumFields = 0;

  for (RecordDecl::field_iterator F = Record->field_begin(),

                               FEnd = Record->field_end();

       F != FEnd; 
++F, ++NumFields85
) {

    if (NumFields >= Known->second.FieldOffsets.size())

      continue;

    FieldOffsets[*F] = Known->second.FieldOffsets[NumFields];

  }

  // Wrong number of fields.

  if (NumFields != Known->second.FieldOffsets.size())

    return false;

  Size = Known->second.Size;

  Alignment = Known->second.Align;

  return true;

}

LLVM_DUMP_METHOD void LayoutOverrideSource::dump() {

  raw_ostream &OS = llvm::errs();

  for (llvm::StringMap<Layout>::iterator L = Layouts.begin(),

                                      LEnd = Layouts.end();

       L != LEnd; ++L) {

    OS << "Type: blah " << L->first() << '\n';

    OS << "  Size:" << L->second.Size << '\n';

    OS << "  Alignment:" << L->second.Align << '\n';

    OS << "  FieldOffsets: [";

    for (unsigned I = 0, N = L->second.FieldOffsets.size(); I != N; ++I) {

      if (I)

        OS << ", ";

      OS << L->second.FieldOffsets[I];

    }

    OS << "]\n";

  }

}