//===-- DWARFDebugInfo.cpp ------------------------------------------------===//
//
// 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 "SymbolFileDWARF.h"

#include <algorithm>
#include <set>

#include "lldb/Host/PosixApi.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/RegularExpression.h"
#include "lldb/Utility/Stream.h"
#include "llvm/Support/Casting.h"

#include "DWARFCompileUnit.h"
#include "DWARFContext.h"
#include "DWARFDebugAranges.h"
#include "DWARFDebugInfo.h"
#include "DWARFDebugInfoEntry.h"
#include "DWARFFormValue.h"
#include "DWARFTypeUnit.h"

using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::plugin::dwarf;

// Constructor
DWARFDebugInfo::DWARFDebugInfo(SymbolFileDWARF &dwarf, DWARFContext &context)
    : m_dwarf(dwarf), m_context(context), m_units(), m_cu_aranges_up() {}

const DWARFDebugAranges &DWARFDebugInfo::GetCompileUnitAranges() {
  if (m_cu_aranges_up)
    return *m_cu_aranges_up;

  m_cu_aranges_up = std::make_unique<DWARFDebugAranges>();
  const DWARFDataExtractor &debug_aranges_data =
      m_context.getOrLoadArangesData();

  // Extract what we can from the .debug_aranges first.
  m_cu_aranges_up->extract(debug_aranges_data);

  // Make a list of all CUs represented by the .debug_aranges data.
  std::set<dw_offset_t> cus_with_data;
  for (size_t n = 0; n < m_cu_aranges_up->GetNumRanges(); n++) {
    dw_offset_t offset = m_cu_aranges_up->OffsetAtIndex(n);
    if (offset != DW_INVALID_OFFSET)
      cus_with_data.insert(offset);
  }

  // Manually build arange data for everything that wasn't in .debug_aranges.
  // The .debug_aranges accelerator is not guaranteed to be complete.
  // Tools such as dsymutil can provide stronger guarantees than required by the
  // standard. Without that guarantee, we have to iterate over every CU in the
  // .debug_info and make sure there's a corresponding entry in the table and if
  // not, add one for every subprogram.
  ObjectFile *OF = m_dwarf.GetObjectFile();
  if (!OF || !OF->CanTrustAddressRanges()) {
    const size_t num_units = GetNumUnits();
    for (size_t idx = 0; idx < num_units; ++idx) {
      DWARFUnit *cu = GetUnitAtIndex(idx);

      dw_offset_t offset = cu->GetOffset();
      if (cus_with_data.find(offset) == cus_with_data.end())
        cu->BuildAddressRangeTable(m_cu_aranges_up.get());
    }
  }

  const bool minimize = true;
  m_cu_aranges_up->Sort(minimize);
  return *m_cu_aranges_up;
}

void DWARFDebugInfo::ParseUnitsFor(DIERef::Section section) {
  DWARFDataExtractor data = section == DIERef::Section::DebugTypes
                                ? m_context.getOrLoadDebugTypesData()
                                : m_context.getOrLoadDebugInfoData();
  lldb::offset_t offset = 0;
  while (data.ValidOffset(offset)) {
    llvm::Expected<DWARFUnitSP> unit_sp = DWARFUnit::extract(
        m_dwarf, m_units.size(), data, section, &offset);

    if (!unit_sp) {
      // FIXME: Propagate this error up.
      llvm::consumeError(unit_sp.takeError());
      return;
    }

    // If it didn't return an error, then it should be returning a valid Unit.
    assert(*unit_sp);
    m_units.push_back(*unit_sp);
    offset = (*unit_sp)->GetNextUnitOffset();

    if (auto *type_unit = llvm::dyn_cast<DWARFTypeUnit>(unit_sp->get())) {
      m_type_hash_to_unit_index.emplace_back(type_unit->GetTypeHash(),
                                             unit_sp.get()->GetID());
    }
  }
}

void DWARFDebugInfo::ParseUnitHeadersIfNeeded() {
  llvm::call_once(m_units_once_flag, [&] {
    ParseUnitsFor(DIERef::Section::DebugInfo);
    ParseUnitsFor(DIERef::Section::DebugTypes);
    llvm::sort(m_type_hash_to_unit_index, llvm::less_first());
  });
}

size_t DWARFDebugInfo::GetNumUnits() {
  ParseUnitHeadersIfNeeded();
  return m_units.size();
}

DWARFUnit *DWARFDebugInfo::GetUnitAtIndex(size_t idx) {
  DWARFUnit *cu = nullptr;
  if (idx < GetNumUnits())
    cu = m_units[idx].get();
  return cu;
}

uint32_t DWARFDebugInfo::FindUnitIndex(DIERef::Section section,
                                       dw_offset_t offset) {
  ParseUnitHeadersIfNeeded();

  // llvm::lower_bound is not used as for DIE offsets it would still return
  // index +1 and GetOffset() returning index itself would be a special case.
  auto pos = llvm::upper_bound(
      m_units, std::make_pair(section, offset),
      [](const std::pair<DIERef::Section, dw_offset_t> &lhs,
         const DWARFUnitSP &rhs) {
        return lhs < std::make_pair(rhs->GetDebugSection(), rhs->GetOffset());
      });
  uint32_t idx = std::distance(m_units.begin(), pos);
  if (idx == 0)
    return DW_INVALID_INDEX;
  return idx - 1;
}

DWARFUnit *DWARFDebugInfo::GetUnitAtOffset(DIERef::Section section,
                                           dw_offset_t cu_offset,
                                           uint32_t *idx_ptr) {
  uint32_t idx = FindUnitIndex(section, cu_offset);
  DWARFUnit *result = GetUnitAtIndex(idx);
  if (result && result->GetOffset() != cu_offset) {
    result = nullptr;
    idx = DW_INVALID_INDEX;
  }
  if (idx_ptr)
    *idx_ptr = idx;
  return result;
}

DWARFUnit *DWARFDebugInfo::GetUnit(const DIERef &die_ref) {
  return GetUnitContainingDIEOffset(die_ref.section(), die_ref.die_offset());
}

DWARFUnit *
DWARFDebugInfo::GetUnitContainingDIEOffset(DIERef::Section section,
                                           dw_offset_t die_offset) {
  uint32_t idx = FindUnitIndex(section, die_offset);
  DWARFUnit *result = GetUnitAtIndex(idx);
  if (result && !result->ContainsDIEOffset(die_offset))
    return nullptr;
  return result;
}

DWARFTypeUnit *DWARFDebugInfo::GetTypeUnitForHash(uint64_t hash) {
  auto pos = llvm::lower_bound(m_type_hash_to_unit_index,
                               std::make_pair(hash, 0u), llvm::less_first());
  if (pos == m_type_hash_to_unit_index.end() || pos->first != hash)
    return nullptr;
  return llvm::cast<DWARFTypeUnit>(GetUnitAtIndex(pos->second));
}

bool DWARFDebugInfo::ContainsTypeUnits() {
  ParseUnitHeadersIfNeeded();
  return !m_type_hash_to_unit_index.empty();
}

// GetDIE()
//
// Get the DIE (Debug Information Entry) with the specified offset.
DWARFDIE
DWARFDebugInfo::GetDIE(const DIERef &die_ref) {
  DWARFUnit *cu = GetUnit(die_ref);
  if (cu)
    return cu->GetNonSkeletonUnit().GetDIE(die_ref.die_offset());
  return DWARFDIE(); // Not found
}