/* Copyright (c) 2008-2022. The SimGrid Team. All rights reserved.          */

/* This program is free software; you can redistribute it and/or modify it
 * under the terms of the license (GNU LGPL) which comes with this package. */

/** \file compare.cpp Memory snapshotting and comparison                    */

#include "src/mc/mc_config.hpp"
#include "src/mc/mc_private.hpp"
#include "src/mc/sosp/Snapshot.hpp"

#include <algorithm>

XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_compare, xbt, "Logging specific to mc_compare in mc");

using simgrid::mc::remote;

namespace simgrid {
namespace mc {

/*********************************** Heap comparison ***********************************/
/***************************************************************************************/

class HeapLocation {
public:
  int block_    = 0;
  int fragment_ = 0;

  HeapLocation() = default;
  explicit HeapLocation(int block, int fragment = 0) : block_(block), fragment_(fragment) {}

  bool operator==(HeapLocation const& that) const
  {
    return block_ == that.block_ && fragment_ == that.fragment_;
  }
  bool operator<(HeapLocation const& that) const
  {
    return std::make_pair(block_, fragment_) < std::make_pair(that.block_, that.fragment_);
  }
};

using HeapLocationPair  = std::array<HeapLocation, 2>;
using HeapLocationPairs = std::set<HeapLocationPair>;

class HeapArea : public HeapLocation {
public:
  bool valid_ = false;
  HeapArea() = default;
  explicit HeapArea(int block) : valid_(true) { block_ = block; }
  HeapArea(int block, int fragment) : valid_(true)
  {
    block_    = block;
    fragment_ = fragment;
  }
};

class ProcessComparisonState {
public:
  const std::vector<IgnoredHeapRegion>* to_ignore = nullptr;
  std::vector<HeapArea> equals_to;
  std::vector<Type*> types;
  std::size_t heapsize = 0;

  void initHeapInformation(const s_xbt_mheap_t* heap, const std::vector<IgnoredHeapRegion>& i);
};

class StateComparator {
public:
  s_xbt_mheap_t std_heap_copy;
  std::size_t heaplimit;
  std::array<ProcessComparisonState, 2> processStates;

  std::unordered_set<std::pair<const void*, const void*>, simgrid::xbt::hash<std::pair<const void*, const void*>>>
      compared_pointers;

  void clear()
  {
    compared_pointers.clear();
  }

  int initHeapInformation(const s_xbt_mheap_t* heap1, const s_xbt_mheap_t* heap2,
                          const std::vector<IgnoredHeapRegion>& i1, const std::vector<IgnoredHeapRegion>& i2);

  template <int rank> HeapArea& equals_to_(std::size_t i, std::size_t j)
  {
    return processStates[rank - 1].equals_to[MAX_FRAGMENT_PER_BLOCK * i + j];
  }
  template <int rank> Type*& types_(std::size_t i, std::size_t j)
  {
    return processStates[rank - 1].types[MAX_FRAGMENT_PER_BLOCK * i + j];
  }

  template <int rank> HeapArea const& equals_to_(std::size_t i, std::size_t j) const
  {
    return processStates[rank - 1].equals_to[MAX_FRAGMENT_PER_BLOCK * i + j];
  }
  template <int rank> Type* const& types_(std::size_t i, std::size_t j) const
  {
    return processStates[rank - 1].types[MAX_FRAGMENT_PER_BLOCK * i + j];
  }

  /** Check whether two blocks are known to be matching
   *
   *  @param b1     Block of state 1
   *  @param b2     Block of state 2
   *  @return       if the blocks are known to be matching
   */
  bool blocksEqual(int b1, int b2) const
  {
    return this->equals_to_<1>(b1, 0).block_ == b2 && this->equals_to_<2>(b2, 0).block_ == b1;
  }

  /** Check whether two fragments are known to be matching
   *
   *  @param b1     Block of state 1
   *  @param f1     Fragment of state 1
   *  @param b2     Block of state 2
   *  @param f2     Fragment of state 2
   *  @return       if the fragments are known to be matching
   */
  int fragmentsEqual(int b1, int f1, int b2, int f2) const
  {
    return this->equals_to_<1>(b1, f1).block_ == b2 && this->equals_to_<1>(b1, f1).fragment_ == f2 &&
           this->equals_to_<2>(b2, f2).block_ == b1 && this->equals_to_<2>(b2, f2).fragment_ == f1;
  }

  void match_equals(const HeapLocationPairs* list);
};

} // namespace mc
} // namespace simgrid

/************************************************************************************/

static ssize_t heap_comparison_ignore_size(const std::vector<simgrid::mc::IgnoredHeapRegion>* ignore_list,
                                           const void* address)
{
  auto pos = std::lower_bound(ignore_list->begin(), ignore_list->end(), address,
                              [](auto const& reg, auto const* addr) { return reg.address < addr; });
  return (pos != ignore_list->end() && pos->address == address) ? pos->size : -1;
}

static bool is_stack(const simgrid::mc::RemoteProcess& process, const void* address)
{
  auto const& stack_areas = process.stack_areas();
  return std::any_of(stack_areas.begin(), stack_areas.end(),
                     [address](auto const& stack) { return stack.address == address; });
}

// TODO, this should depend on the snapshot?
static bool is_block_stack(const simgrid::mc::RemoteProcess& process, int block)
{
  auto const& stack_areas = process.stack_areas();
  return std::any_of(stack_areas.begin(), stack_areas.end(),
                     [block](auto const& stack) { return stack.block == block; });
}

namespace simgrid {
namespace mc {

void StateComparator::match_equals(const HeapLocationPairs* list)
{
  for (auto const& pair : *list) {
    if (pair[0].fragment_ != -1) {
      this->equals_to_<1>(pair[0].block_, pair[0].fragment_) = HeapArea(pair[1].block_, pair[1].fragment_);
      this->equals_to_<2>(pair[1].block_, pair[1].fragment_) = HeapArea(pair[0].block_, pair[0].fragment_);
    } else {
      this->equals_to_<1>(pair[0].block_, 0) = HeapArea(pair[1].block_, pair[1].fragment_);
      this->equals_to_<2>(pair[1].block_, 0) = HeapArea(pair[0].block_, pair[0].fragment_);
    }
  }
}

void ProcessComparisonState::initHeapInformation(const s_xbt_mheap_t* heap, const std::vector<IgnoredHeapRegion>& i)
{
  auto heaplimit  = heap->heaplimit;
  this->heapsize  = heap->heapsize;
  this->to_ignore = &i;
  this->equals_to.assign(heaplimit * MAX_FRAGMENT_PER_BLOCK, HeapArea());
  this->types.assign(heaplimit * MAX_FRAGMENT_PER_BLOCK, nullptr);
}

int StateComparator::initHeapInformation(const s_xbt_mheap_t* heap1, const s_xbt_mheap_t* heap2,
                                         const std::vector<IgnoredHeapRegion>& i1,
                                         const std::vector<IgnoredHeapRegion>& i2)
{
  if ((heap1->heaplimit != heap2->heaplimit) || (heap1->heapsize != heap2->heapsize))
    return -1;
  this->heaplimit     = heap1->heaplimit;
  this->std_heap_copy = *mc_model_checker->get_remote_process().get_heap();
  this->processStates[0].initHeapInformation(heap1, i1);
  this->processStates[1].initHeapInformation(heap2, i2);
  return 0;
}

// TODO, have a robust way to find it in O(1)
static inline Region* MC_get_heap_region(const Snapshot& snapshot)
{
  for (auto const& region : snapshot.snapshot_regions_)
    if (region->region_type() == RegionType::Heap)
      return region.get();
  xbt_die("No heap region");
}

static bool heap_area_differ(const RemoteProcess& process, StateComparator& state, const void* area1, const void* area2,
                             const Snapshot& snapshot1, const Snapshot& snapshot2, HeapLocationPairs* previous,
                             Type* type, int pointer_level);

static bool mmalloc_heap_differ(const RemoteProcess& process, StateComparator& state, const Snapshot& snapshot1,
                                const Snapshot& snapshot2)
{
  /* Check busy blocks */
  size_t i1 = 1;

  malloc_info heapinfo_temp1;
  malloc_info heapinfo_temp2;
  malloc_info heapinfo_temp2b;

  const Region* heap_region1 = MC_get_heap_region(snapshot1);
  const Region* heap_region2 = MC_get_heap_region(snapshot2);

  // This is the address of std_heap->heapinfo in the application process:
  uint64_t heapinfo_address = process.heap_address.address() + offsetof(s_xbt_mheap_t, heapinfo);

  // This is in snapshot do not use them directly:
  const malloc_info* heapinfos1 = snapshot1.read(remote<malloc_info*>(heapinfo_address));
  const malloc_info* heapinfos2 = snapshot2.read(remote<malloc_info*>(heapinfo_address));

  while (i1 < state.heaplimit) {
    const auto* heapinfo1 =
        static_cast<malloc_info*>(heap_region1->read(&heapinfo_temp1, &heapinfos1[i1], sizeof(malloc_info)));
    const auto* heapinfo2 =
        static_cast<malloc_info*>(heap_region2->read(&heapinfo_temp2, &heapinfos2[i1], sizeof(malloc_info)));

    if (heapinfo1->type == MMALLOC_TYPE_FREE || heapinfo1->type == MMALLOC_TYPE_HEAPINFO) {      /* Free block */
      i1 ++;
      continue;
    }

    xbt_assert(heapinfo1->type >= 0, "Unknown mmalloc block type: %d", heapinfo1->type);

    void* addr_block1 = (ADDR2UINT(i1) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;

    if (heapinfo1->type == MMALLOC_TYPE_UNFRAGMENTED) { /* Large block */
      if (is_stack(process, addr_block1)) {
        for (size_t k = 0; k < heapinfo1->busy_block.size; k++)
          state.equals_to_<1>(i1 + k, 0) = HeapArea(i1, -1);
        for (size_t k = 0; k < heapinfo2->busy_block.size; k++)
          state.equals_to_<2>(i1 + k, 0) = HeapArea(i1, -1);
        i1 += heapinfo1->busy_block.size;
        continue;
      }

      if (state.equals_to_<1>(i1, 0).valid_) {
        i1++;
        continue;
      }

      size_t i2 = 1;
      bool equal = false;

      /* Try first to associate to same block in the other heap */
      if (heapinfo2->type == heapinfo1->type && state.equals_to_<2>(i1, 0).valid_ == 0) {
        const void* addr_block2 = (ADDR2UINT(i1) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;
        if (not heap_area_differ(process, state, addr_block1, addr_block2, snapshot1, snapshot2, nullptr, nullptr, 0)) {
          for (size_t k = 1; k < heapinfo2->busy_block.size; k++)
            state.equals_to_<2>(i1 + k, 0) = HeapArea(i1, -1);
          for (size_t k = 1; k < heapinfo1->busy_block.size; k++)
            state.equals_to_<1>(i1 + k, 0) = HeapArea(i1, -1);
          equal = true;
          i1 += heapinfo1->busy_block.size;
        }
      }

      while (i2 < state.heaplimit && not equal) {
        const void* addr_block2 = (ADDR2UINT(i2) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;

        if (i2 == i1) {
          i2++;
          continue;
        }

        const auto* heapinfo2b =
            static_cast<malloc_info*>(heap_region2->read(&heapinfo_temp2b, &heapinfos2[i2], sizeof(malloc_info)));

        if (heapinfo2b->type != MMALLOC_TYPE_UNFRAGMENTED) {
          i2++;
          continue;
        }

        if (state.equals_to_<2>(i2, 0).valid_) {
          i2++;
          continue;
        }

        if (not heap_area_differ(process, state, addr_block1, addr_block2, snapshot1, snapshot2, nullptr, nullptr, 0)) {
          for (size_t k = 1; k < heapinfo2b->busy_block.size; k++)
            state.equals_to_<2>(i2 + k, 0) = HeapArea(i1, -1);
          for (size_t k = 1; k < heapinfo1->busy_block.size; k++)
            state.equals_to_<1>(i1 + k, 0) = HeapArea(i2, -1);
          equal = true;
          i1 += heapinfo1->busy_block.size;
        }
        i2++;
      }

      if (not equal) {
        XBT_DEBUG("Block %zu not found (size_used = %zu, addr = %p)", i1, heapinfo1->busy_block.busy_size, addr_block1);
        return true;
      }
    } else { /* Fragmented block */
      for (size_t j1 = 0; j1 < (size_t)(BLOCKSIZE >> heapinfo1->type); j1++) {
        if (heapinfo1->busy_frag.frag_size[j1] == -1) /* Free fragment_ */
          continue;

        if (state.equals_to_<1>(i1, j1).valid_)
          continue;

        void* addr_frag1 = (char*)addr_block1 + (j1 << heapinfo1->type);

        size_t i2 = 1;
        bool equal = false;

        /* Try first to associate to same fragment_ in the other heap */
        if (heapinfo2->type == heapinfo1->type && not state.equals_to_<2>(i1, j1).valid_) {
          const void* addr_block2 = (ADDR2UINT(i1) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;
          const void* addr_frag2  = (const char*)addr_block2 + (j1 << heapinfo2->type);
          if (not heap_area_differ(process, state, addr_frag1, addr_frag2, snapshot1, snapshot2, nullptr, nullptr, 0))
            equal = true;
        }

        while (i2 < state.heaplimit && not equal) {
          const auto* heapinfo2b =
              static_cast<malloc_info*>(heap_region2->read(&heapinfo_temp2b, &heapinfos2[i2], sizeof(malloc_info)));

          if (heapinfo2b->type == MMALLOC_TYPE_FREE || heapinfo2b->type == MMALLOC_TYPE_HEAPINFO) {
            i2 ++;
            continue;
          }

          // We currently do not match fragments with unfragmented blocks (maybe we should).
          if (heapinfo2b->type == MMALLOC_TYPE_UNFRAGMENTED) {
            i2++;
            continue;
          }

          xbt_assert(heapinfo2b->type >= 0, "Unknown mmalloc block type: %d", heapinfo2b->type);

          for (size_t j2 = 0; j2 < (size_t)(BLOCKSIZE >> heapinfo2b->type); j2++) {
            if (i2 == i1 && j2 == j1)
              continue;

            if (state.equals_to_<2>(i2, j2).valid_)
              continue;

            const void* addr_block2 = (ADDR2UINT(i2) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;
            const void* addr_frag2  = (const char*)addr_block2 + (j2 << heapinfo2b->type);

            if (not heap_area_differ(process, state, addr_frag1, addr_frag2, snapshot1, snapshot2, nullptr, nullptr,
                                     0)) {
              equal = true;
              break;
            }
          }
          i2++;
        }

        if (not equal) {
          XBT_DEBUG("Block %zu, fragment_ %zu not found (size_used = %zd, address = %p)\n", i1, j1,
                    heapinfo1->busy_frag.frag_size[j1], addr_frag1);
          return true;
        }
      }
      i1++;
    }
  }

  /* All blocks/fragments are equal to another block/fragment_ ? */
  for (size_t i = 1; i < state.heaplimit; i++) {
    const auto* heapinfo1 =
        static_cast<malloc_info*>(heap_region1->read(&heapinfo_temp1, &heapinfos1[i], sizeof(malloc_info)));

    if (heapinfo1->type == MMALLOC_TYPE_UNFRAGMENTED && i1 == state.heaplimit && heapinfo1->busy_block.busy_size > 0 &&
        not state.equals_to_<1>(i, 0).valid_) {
      XBT_DEBUG("Block %zu not found (size used = %zu)", i, heapinfo1->busy_block.busy_size);
      return true;
    }

    if (heapinfo1->type <= 0)
      continue;
    for (size_t j = 0; j < (size_t)(BLOCKSIZE >> heapinfo1->type); j++)
      if (i1 == state.heaplimit && heapinfo1->busy_frag.frag_size[j] > 0 && not state.equals_to_<1>(i, j).valid_) {
        XBT_DEBUG("Block %zu, Fragment %zu not found (size used = %zd)", i, j, heapinfo1->busy_frag.frag_size[j]);
        return true;
      }
  }

  for (size_t i = 1; i < state.heaplimit; i++) {
    const auto* heapinfo2 =
        static_cast<malloc_info*>(heap_region2->read(&heapinfo_temp2, &heapinfos2[i], sizeof(malloc_info)));
    if (heapinfo2->type == MMALLOC_TYPE_UNFRAGMENTED && i1 == state.heaplimit && heapinfo2->busy_block.busy_size > 0 &&
        not state.equals_to_<2>(i, 0).valid_) {
      XBT_DEBUG("Block %zu not found (size used = %zu)", i,
                heapinfo2->busy_block.busy_size);
      return true;
    }

    if (heapinfo2->type <= 0)
      continue;

    for (size_t j = 0; j < (size_t)(BLOCKSIZE >> heapinfo2->type); j++)
      if (i1 == state.heaplimit && heapinfo2->busy_frag.frag_size[j] > 0 && not state.equals_to_<2>(i, j).valid_) {
        XBT_DEBUG("Block %zu, Fragment %zu not found (size used = %zd)",
          i, j, heapinfo2->busy_frag.frag_size[j]);
        return true;
      }
  }
  return false;
}

/**
 *
 * @param state
 * @param real_area1     Process address for state 1
 * @param real_area2     Process address for state 2
 * @param snapshot1      Snapshot of state 1
 * @param snapshot2      Snapshot of state 2
 * @param previous
 * @param size
 * @param check_ignore
 * @return true when different, false otherwise (same or unknown)
 */
static bool heap_area_differ_without_type(const RemoteProcess& process, StateComparator& state, const void* real_area1,
                                          const void* real_area2, const Snapshot& snapshot1, const Snapshot& snapshot2,
                                          HeapLocationPairs* previous, int size, int check_ignore)
{
  const Region* heap_region1  = MC_get_heap_region(snapshot1);
  const Region* heap_region2  = MC_get_heap_region(snapshot2);

  for (int i = 0; i < size; ) {
    if (check_ignore > 0) {
      ssize_t ignore1 = heap_comparison_ignore_size(state.processStates[0].to_ignore, (const char*)real_area1 + i);
      if (ignore1 != -1) {
        ssize_t ignore2 = heap_comparison_ignore_size(state.processStates[1].to_ignore, (const char*)real_area2 + i);
        if (ignore2 == ignore1) {
          if (ignore1 == 0) {
            return false;
          } else {
            i = i + ignore2;
            check_ignore--;
            continue;
          }
        }
      }
    }

    if (MC_snapshot_region_memcmp((const char*)real_area1 + i, heap_region1, (const char*)real_area2 + i, heap_region2,
                                  1) != 0) {
      int pointer_align = (i / sizeof(void *)) * sizeof(void *);
      const void* addr_pointed1 = snapshot1.read(remote((void* const*)((const char*)real_area1 + pointer_align)));
      const void* addr_pointed2 = snapshot2.read(remote((void* const*)((const char*)real_area2 + pointer_align)));

      if (process.in_maestro_stack(remote(addr_pointed1)) && process.in_maestro_stack(remote(addr_pointed2))) {
        i = pointer_align + sizeof(void *);
        continue;
      }

      if (snapshot1.on_heap(addr_pointed1) && snapshot2.on_heap(addr_pointed2)) {
        // Both addresses are in the heap:
        if (heap_area_differ(process, state, addr_pointed1, addr_pointed2, snapshot1, snapshot2, previous, nullptr, 0))
          return true;
        i = pointer_align + sizeof(void *);
        continue;
      }
      return true;
    }
    i++;
  }
  return false;
}

/**
 *
 * @param state
 * @param real_area1     Process address for state 1
 * @param real_area2     Process address for state 2
 * @param snapshot1      Snapshot of state 1
 * @param snapshot2      Snapshot of state 2
 * @param previous
 * @param type
 * @param area_size      either a byte_size or an elements_count (?)
 * @param check_ignore
 * @param pointer_level
 * @return               true when different, false otherwise (same or unknown)
 */
static bool heap_area_differ_with_type(const simgrid::mc::RemoteProcess& process, StateComparator& state,
                                       const void* real_area1, const void* real_area2, const Snapshot& snapshot1,
                                       const Snapshot& snapshot2, HeapLocationPairs* previous, const Type* type,
                                       int area_size, int check_ignore, int pointer_level)
{
  // HACK: This should not happen but in practice, there are some
  // DW_TAG_typedef without an associated DW_AT_type:
  //<1><538832>: Abbrev Number: 111 (DW_TAG_typedef)
  //    <538833>   DW_AT_name        : (indirect string, offset: 0x2292f3): gregset_t
  //    <538837>   DW_AT_decl_file   : 98
  //    <538838>   DW_AT_decl_line   : 37
  if (type == nullptr)
    return false;

  if (is_stack(process, real_area1) && is_stack(process, real_area2))
    return false;

  if (check_ignore > 0) {
    ssize_t ignore1 = heap_comparison_ignore_size(state.processStates[0].to_ignore, real_area1);
    if (ignore1 > 0 && heap_comparison_ignore_size(state.processStates[1].to_ignore, real_area2) == ignore1)
      return false;
  }

  const Type* subtype;
  const Type* subsubtype;
  int elm_size;
  const void* addr_pointed1;
  const void* addr_pointed2;

  const Region* heap_region1 = MC_get_heap_region(snapshot1);
  const Region* heap_region2 = MC_get_heap_region(snapshot2);

  switch (type->type) {
    case DW_TAG_unspecified_type:
      return true;

    case DW_TAG_base_type:
      if (not type->name.empty() && type->name == "char") { /* String, hence random (arbitrary ?) size */
        if (real_area1 == real_area2)
          return false;
        else
          return MC_snapshot_region_memcmp(real_area1, heap_region1, real_area2, heap_region2, area_size) != 0;
      } else {
        if (area_size != -1 && type->byte_size != area_size)
          return false;
        else
          return MC_snapshot_region_memcmp(real_area1, heap_region1, real_area2, heap_region2, type->byte_size) != 0;
      }

    case DW_TAG_enumeration_type:
      if (area_size != -1 && type->byte_size != area_size)
        return false;
      return MC_snapshot_region_memcmp(real_area1, heap_region1, real_area2, heap_region2, type->byte_size) != 0;

    case DW_TAG_typedef:
    case DW_TAG_const_type:
    case DW_TAG_volatile_type:
      return heap_area_differ_with_type(process, state, real_area1, real_area2, snapshot1, snapshot2, previous,
                                        type->subtype, area_size, check_ignore, pointer_level);

    case DW_TAG_array_type:
      subtype = type->subtype;
      switch (subtype->type) {
        case DW_TAG_unspecified_type:
          return true;

        case DW_TAG_base_type:
        case DW_TAG_enumeration_type:
        case DW_TAG_pointer_type:
        case DW_TAG_reference_type:
        case DW_TAG_rvalue_reference_type:
        case DW_TAG_structure_type:
        case DW_TAG_class_type:
        case DW_TAG_union_type:
          if (subtype->full_type)
            subtype = subtype->full_type;
          elm_size  = subtype->byte_size;
          break;
        // TODO, just remove the type indirection?
        case DW_TAG_const_type:
        case DW_TAG_typedef:
        case DW_TAG_volatile_type:
          subsubtype = subtype->subtype;
          if (subsubtype->full_type)
            subsubtype = subsubtype->full_type;
          elm_size     = subsubtype->byte_size;
          break;
        default:
          return false;
      }
      for (int i = 0; i < type->element_count; i++) {
        // TODO, add support for variable stride (DW_AT_byte_stride)
        if (heap_area_differ_with_type(process, state, (const char*)real_area1 + (i * elm_size),
                                       (const char*)real_area2 + (i * elm_size), snapshot1, snapshot2, previous,
                                       type->subtype, subtype->byte_size, check_ignore, pointer_level))
          return true;
      }
      return false;

    case DW_TAG_reference_type:
    case DW_TAG_rvalue_reference_type:
    case DW_TAG_pointer_type:
      if (type->subtype && type->subtype->type == DW_TAG_subroutine_type) {
        addr_pointed1 = snapshot1.read(remote((void* const*)real_area1));
        addr_pointed2 = snapshot2.read(remote((void* const*)real_area2));
        return (addr_pointed1 != addr_pointed2);
      }
      pointer_level++;
      if (pointer_level <= 1) {
        addr_pointed1 = snapshot1.read(remote((void* const*)real_area1));
        addr_pointed2 = snapshot2.read(remote((void* const*)real_area2));
        if (snapshot1.on_heap(addr_pointed1) && snapshot2.on_heap(addr_pointed2))
          return heap_area_differ(process, state, addr_pointed1, addr_pointed2, snapshot1, snapshot2, previous,
                                  type->subtype, pointer_level);
        else
          return (addr_pointed1 != addr_pointed2);
      }
      for (size_t i = 0; i < (area_size / sizeof(void*)); i++) {
        addr_pointed1 = snapshot1.read(remote((void* const*)((const char*)real_area1 + i * sizeof(void*))));
        addr_pointed2 = snapshot2.read(remote((void* const*)((const char*)real_area2 + i * sizeof(void*))));
        bool differ   = snapshot1.on_heap(addr_pointed1) && snapshot2.on_heap(addr_pointed2)
                            ? heap_area_differ(process, state, addr_pointed1, addr_pointed2, snapshot1, snapshot2,
                                             previous, type->subtype, pointer_level)
                            : addr_pointed1 != addr_pointed2;
        if (differ)
          return true;
      }
      return false;

    case DW_TAG_structure_type:
    case DW_TAG_class_type:
      if (type->full_type)
        type = type->full_type;
      if (type->byte_size == 0)
        return false;
      if (area_size != -1 && type->byte_size != area_size) {
        if (area_size <= type->byte_size || area_size % type->byte_size != 0)
          return false;
        for (size_t i = 0; i < (size_t)(area_size / type->byte_size); i++) {
          if (heap_area_differ_with_type(process, state, (const char*)real_area1 + i * type->byte_size,
                                         (const char*)real_area2 + i * type->byte_size, snapshot1, snapshot2, previous,
                                         type, -1, check_ignore, 0))
            return true;
        }
        } else {
          for (const simgrid::mc::Member& member : type->members) {
            // TODO, optimize this? (for the offset case)
            const void* real_member1 = dwarf::resolve_member(real_area1, type, &member, &snapshot1);
            const void* real_member2 = dwarf::resolve_member(real_area2, type, &member, &snapshot2);
            if (heap_area_differ_with_type(process, state, real_member1, real_member2, snapshot1, snapshot2, previous,
                                           member.type, -1, check_ignore, 0))
              return true;
          }
        }
        return false;

    case DW_TAG_union_type:
      return heap_area_differ_without_type(process, state, real_area1, real_area2, snapshot1, snapshot2, previous,
                                           type->byte_size, check_ignore);

    default:
      THROW_IMPOSSIBLE;
  }
}

/** Infer the type of a part of the block from the type of the block
 *
 * TODO, handle DW_TAG_array_type as well as arrays of the object ((*p)[5], p[5])
 *
 * TODO, handle subfields ((*p).bar.foo, (*p)[5].bar…)
 *
 * @param  type               DWARF type ID of the root address
 * @param  area_size
 * @return                    DWARF type ID for given offset
 */
static Type* get_offset_type(void* real_base_address, Type* type, int offset, int area_size, const Snapshot& snapshot)
{
  // Beginning of the block, the inferred variable type if the type of the block:
  if (offset == 0)
    return type;

  switch (type->type) {
  case DW_TAG_structure_type:
  case DW_TAG_class_type:
    if (type->full_type)
      type = type->full_type;
    if (area_size != -1 && type->byte_size != area_size) {
      if (area_size > type->byte_size && area_size % type->byte_size == 0)
        return type;
      else
        return nullptr;
    }

    for (const simgrid::mc::Member& member : type->members) {
      if (member.has_offset_location()) {
        // We have the offset, use it directly (shortcut):
        if (member.offset() == offset)
          return member.type;
      } else {
        void* real_member = dwarf::resolve_member(real_base_address, type, &member, &snapshot);
        if ((char*)real_member - (char*)real_base_address == offset)
          return member.type;
      }
    }
    return nullptr;

  default:
    /* FIXME: other cases ? */
    return nullptr;
  }
}

/**
 *
 * @param area1          Process address for state 1
 * @param area2          Process address for state 2
 * @param snapshot1      Snapshot of state 1
 * @param snapshot2      Snapshot of state 2
 * @param previous       Pairs of blocks already compared on the current path (or nullptr)
 * @param type_id        Type of variable
 * @param pointer_level
 * @return true when different, false otherwise (same or unknown)
 */
static bool heap_area_differ(const RemoteProcess& process, StateComparator& state, const void* area1, const void* area2,
                             const Snapshot& snapshot1, const Snapshot& snapshot2, HeapLocationPairs* previous,
                             Type* type, int pointer_level)
{
  ssize_t block1;
  ssize_t block2;
  ssize_t size;
  int check_ignore = 0;

  int type_size = -1;
  int offset1   = 0;
  int offset2   = 0;
  int new_size1 = -1;
  int new_size2 = -1;

  Type* new_type1 = nullptr;

  bool match_pairs = false;

  // This is the address of std_heap->heapinfo in the application process:
  uint64_t heapinfo_address = process.heap_address.address() + offsetof(s_xbt_mheap_t, heapinfo);

  const malloc_info* heapinfos1 = snapshot1.read(remote<malloc_info*>(heapinfo_address));
  const malloc_info* heapinfos2 = snapshot2.read(remote<malloc_info*>(heapinfo_address));

  malloc_info heapinfo_temp1;
  malloc_info heapinfo_temp2;

  simgrid::mc::HeapLocationPairs current;
  if (previous == nullptr) {
    previous = &current;
    match_pairs = true;
  }

  // Get block number:
  block1 = ((const char*)area1 - (const char*)state.std_heap_copy.heapbase) / BLOCKSIZE + 1;
  block2 = ((const char*)area2 - (const char*)state.std_heap_copy.heapbase) / BLOCKSIZE + 1;

  // If either block is a stack block:
  if (is_block_stack(process, (int)block1) && is_block_stack(process, (int)block2)) {
    previous->insert(HeapLocationPair{{HeapLocation(block1, -1), HeapLocation(block2, -1)}});
    if (match_pairs)
      state.match_equals(previous);
    return false;
  }

  // If either block is not in the expected area of memory:
  if (((const char*)area1 < (const char*)state.std_heap_copy.heapbase) ||
      (block1 > (ssize_t)state.processStates[0].heapsize) || (block1 < 1) ||
      ((const char*)area2 < (const char*)state.std_heap_copy.heapbase) ||
      (block2 > (ssize_t)state.processStates[1].heapsize) || (block2 < 1)) {
    return true;
  }

  // Process address of the block:
  void* real_addr_block1 = (ADDR2UINT(block1) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;
  void* real_addr_block2 = (ADDR2UINT(block2) - 1) * BLOCKSIZE + (char*)state.std_heap_copy.heapbase;

  if (type) {
    if (type->full_type)
      type = type->full_type;

    // This assume that for "boring" types (volatile ...) byte_size is absent:
    while (type->byte_size == 0 && type->subtype != nullptr)
      type = type->subtype;

    // Find type_size:
    if (type->type == DW_TAG_pointer_type ||
        (type->type == DW_TAG_base_type && not type->name.empty() && type->name == "char"))
      type_size = -1;
    else
      type_size = type->byte_size;
  }

  const Region* heap_region1 = MC_get_heap_region(snapshot1);
  const Region* heap_region2 = MC_get_heap_region(snapshot2);

  const auto* heapinfo1 =
      static_cast<malloc_info*>(heap_region1->read(&heapinfo_temp1, &heapinfos1[block1], sizeof(malloc_info)));
  const auto* heapinfo2 =
      static_cast<malloc_info*>(heap_region2->read(&heapinfo_temp2, &heapinfos2[block2], sizeof(malloc_info)));

  if ((heapinfo1->type == MMALLOC_TYPE_FREE || heapinfo1->type==MMALLOC_TYPE_HEAPINFO)
    && (heapinfo2->type == MMALLOC_TYPE_FREE || heapinfo2->type ==MMALLOC_TYPE_HEAPINFO)) {
    /* Free block */
    if (match_pairs)
      state.match_equals(previous);
    return false;
  }

  if (heapinfo1->type == MMALLOC_TYPE_UNFRAGMENTED && heapinfo2->type == MMALLOC_TYPE_UNFRAGMENTED) {
    /* Complete block */

    // TODO, lookup variable type from block type as done for fragmented blocks

    if (state.equals_to_<1>(block1, 0).valid_ && state.equals_to_<2>(block2, 0).valid_ &&
        state.blocksEqual(block1, block2)) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    if (type_size != -1 && type_size != (ssize_t)heapinfo1->busy_block.busy_size &&
        type_size != (ssize_t)heapinfo2->busy_block.busy_size &&
        (type->name.empty() || type->name == "struct s_smx_context")) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    if (heapinfo1->busy_block.size != heapinfo2->busy_block.size ||
        heapinfo1->busy_block.busy_size != heapinfo2->busy_block.busy_size)
      return true;

    if (not previous->insert(HeapLocationPair{{HeapLocation(block1, -1), HeapLocation(block2, -1)}}).second) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    size = heapinfo1->busy_block.busy_size;

    // Remember (basic) type inference.
    // The current data structure only allows us to do this for the whole block.
    if (type != nullptr && area1 == real_addr_block1)
      state.types_<1>(block1, 0) = type;
    if (type != nullptr && area2 == real_addr_block2)
      state.types_<2>(block2, 0) = type;

    if (size <= 0) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    if (heapinfo1->busy_block.ignore > 0 && heapinfo2->busy_block.ignore == heapinfo1->busy_block.ignore)
      check_ignore = heapinfo1->busy_block.ignore;

  } else if ((heapinfo1->type > 0) && (heapinfo2->type > 0)) {      /* Fragmented block */
    // Fragment number:
    ssize_t frag1 = (ADDR2UINT(area1) % BLOCKSIZE) >> heapinfo1->type;
    ssize_t frag2 = (ADDR2UINT(area2) % BLOCKSIZE) >> heapinfo2->type;

    // Process address of the fragment_:
    void* real_addr_frag1 = (char*)real_addr_block1 + (frag1 << heapinfo1->type);
    void* real_addr_frag2 = (char*)real_addr_block2 + (frag2 << heapinfo2->type);

    // Check the size of the fragments against the size of the type:
    if (type_size != -1) {
      if (heapinfo1->busy_frag.frag_size[frag1] == -1 || heapinfo2->busy_frag.frag_size[frag2] == -1) {
        if (match_pairs)
          state.match_equals(previous);
        return false;
      }
      // ?
      if (type_size != heapinfo1->busy_frag.frag_size[frag1]
          || type_size != heapinfo2->busy_frag.frag_size[frag2]) {
        if (match_pairs)
          state.match_equals(previous);
        return false;
      }
    }

    // Check if the blocks are already matched together:
    if (state.equals_to_<1>(block1, frag1).valid_ && state.equals_to_<2>(block2, frag2).valid_ &&
        state.fragmentsEqual(block1, frag1, block2, frag2)) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }
    // Compare the size of both fragments:
    if (heapinfo1->busy_frag.frag_size[frag1] != heapinfo2->busy_frag.frag_size[frag2]) {
      if (type_size == -1) {
        if (match_pairs)
          state.match_equals(previous);
        return false;
      } else
        return true;
    }

    // Size of the fragment_:
    size = heapinfo1->busy_frag.frag_size[frag1];

    // Remember (basic) type inference.
    // The current data structure only allows us to do this for the whole fragment_.
    if (type != nullptr && area1 == real_addr_frag1)
      state.types_<1>(block1, frag1) = type;
    if (type != nullptr && area2 == real_addr_frag2)
      state.types_<2>(block2, frag2) = type;

    // The type of the variable is already known:
    if (type) {
      new_type1 = type;
    }
    // Type inference from the block type.
    else if (state.types_<1>(block1, frag1) != nullptr || state.types_<2>(block2, frag2) != nullptr) {
      Type* new_type2 = nullptr;

      offset1 = (const char*)area1 - (const char*)real_addr_frag1;
      offset2 = (const char*)area2 - (const char*)real_addr_frag2;

      if (state.types_<1>(block1, frag1) != nullptr && state.types_<2>(block2, frag2) != nullptr) {
        new_type1 = get_offset_type(real_addr_frag1, state.types_<1>(block1, frag1), offset1, size, snapshot1);
        new_type2 = get_offset_type(real_addr_frag2, state.types_<2>(block2, frag2), offset1, size, snapshot2);
      } else if (state.types_<1>(block1, frag1) != nullptr) {
        new_type1 = get_offset_type(real_addr_frag1, state.types_<1>(block1, frag1), offset1, size, snapshot1);
        new_type2 = get_offset_type(real_addr_frag2, state.types_<1>(block1, frag1), offset2, size, snapshot2);
      } else if (state.types_<2>(block2, frag2) != nullptr) {
        new_type1 = get_offset_type(real_addr_frag1, state.types_<2>(block2, frag2), offset1, size, snapshot1);
        new_type2 = get_offset_type(real_addr_frag2, state.types_<2>(block2, frag2), offset2, size, snapshot2);
      } else {
        if (match_pairs)
          state.match_equals(previous);
        return false;
      }

      if (new_type1 != nullptr && new_type2 != nullptr && new_type1 != new_type2) {
        type = new_type1;
        while (type->byte_size == 0 && type->subtype != nullptr)
          type = type->subtype;
        new_size1 = type->byte_size;

        type = new_type2;
        while (type->byte_size == 0 && type->subtype != nullptr)
          type = type->subtype;
        new_size2 = type->byte_size;

      } else {
        if (match_pairs)
          state.match_equals(previous);
        return false;
      }
    }

    if (new_size1 > 0 && new_size1 == new_size2) {
      type = new_type1;
      size = new_size1;
    }

    if (offset1 == 0 && offset2 == 0 &&
        not previous->insert(HeapLocationPair{{HeapLocation(block1, frag1), HeapLocation(block2, frag2)}}).second) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    if (size <= 0) {
      if (match_pairs)
        state.match_equals(previous);
      return false;
    }

    if ((heapinfo1->busy_frag.ignore[frag1] > 0) &&
        (heapinfo2->busy_frag.ignore[frag2] == heapinfo1->busy_frag.ignore[frag1]))
      check_ignore = heapinfo1->busy_frag.ignore[frag1];
  } else
    return true;

  /* Start comparison */
  bool differ = type ? heap_area_differ_with_type(process, state, area1, area2, snapshot1, snapshot2, previous, type,
                                                  size, check_ignore, pointer_level)
                     : heap_area_differ_without_type(process, state, area1, area2, snapshot1, snapshot2, previous, size,
                                                     check_ignore);
  if (differ)
    return true;

  if (match_pairs)
    state.match_equals(previous);
  return false;
}
} // namespace mc
} // namespace simgrid

/************************** Snapshot comparison *******************************/
/******************************************************************************/

static bool areas_differ_with_type(const simgrid::mc::RemoteProcess& process, simgrid::mc::StateComparator& state,
                                   const void* real_area1, const simgrid::mc::Snapshot& snapshot1,
                                   simgrid::mc::Region* region1, const void* real_area2,
                                   const simgrid::mc::Snapshot& snapshot2, simgrid::mc::Region* region2,
                                   const simgrid::mc::Type* type, int pointer_level)
{
  const simgrid::mc::Type* subtype;
  const simgrid::mc::Type* subsubtype;
  int elm_size;

  xbt_assert(type != nullptr);
  switch (type->type) {
    case DW_TAG_unspecified_type:
      return true;

    case DW_TAG_base_type:
    case DW_TAG_enumeration_type:
    case DW_TAG_union_type:
      return MC_snapshot_region_memcmp(real_area1, region1, real_area2, region2, type->byte_size) != 0;
    case DW_TAG_typedef:
    case DW_TAG_volatile_type:
    case DW_TAG_const_type:
      return areas_differ_with_type(process, state, real_area1, snapshot1, region1, real_area2, snapshot2, region2,
                                    type->subtype, pointer_level);
    case DW_TAG_array_type:
      subtype = type->subtype;
      switch (subtype->type) {
        case DW_TAG_unspecified_type:
          return true;

        case DW_TAG_base_type:
        case DW_TAG_enumeration_type:
        case DW_TAG_pointer_type:
        case DW_TAG_reference_type:
        case DW_TAG_rvalue_reference_type:
        case DW_TAG_structure_type:
        case DW_TAG_class_type:
        case DW_TAG_union_type:
          if (subtype->full_type)
            subtype = subtype->full_type;
          elm_size  = subtype->byte_size;
          break;
        case DW_TAG_const_type:
        case DW_TAG_typedef:
        case DW_TAG_volatile_type:
          subsubtype = subtype->subtype;
          if (subsubtype->full_type)
            subsubtype = subsubtype->full_type;
          elm_size     = subsubtype->byte_size;
          break;
        default:
          return false;
      }
      for (int i = 0; i < type->element_count; i++) {
        size_t off = i * elm_size;
        if (areas_differ_with_type(process, state, (const char*)real_area1 + off, snapshot1, region1,
                                   (const char*)real_area2 + off, snapshot2, region2, type->subtype, pointer_level))
          return true;
      }
      break;
    case DW_TAG_pointer_type:
    case DW_TAG_reference_type:
    case DW_TAG_rvalue_reference_type: {
      const void* addr_pointed1 = MC_region_read_pointer(region1, real_area1);
      const void* addr_pointed2 = MC_region_read_pointer(region2, real_area2);

      if (type->subtype && type->subtype->type == DW_TAG_subroutine_type)
        return (addr_pointed1 != addr_pointed2);
      if (addr_pointed1 == nullptr && addr_pointed2 == nullptr)
        return false;
      if (addr_pointed1 == nullptr || addr_pointed2 == nullptr)
        return true;
      if (not state.compared_pointers.insert(std::make_pair(addr_pointed1, addr_pointed2)).second)
        return false;

      pointer_level++;

      // Some cases are not handled here:
      // * the pointers lead to different areas (one to the heap, the other to the RW segment ...)
      // * a pointer leads to the read-only segment of the current object
      // * a pointer lead to a different ELF object

      if (snapshot1.on_heap(addr_pointed1)) {
        if (not snapshot2.on_heap(addr_pointed2))
          return true;
        // The pointers are both in the heap:
        return simgrid::mc::heap_area_differ(process, state, addr_pointed1, addr_pointed2, snapshot1, snapshot2,
                                             nullptr, type->subtype, pointer_level);

      } else if (region1->contain(simgrid::mc::remote(addr_pointed1))) {
        // The pointers are both in the current object R/W segment:
        if (not region2->contain(simgrid::mc::remote(addr_pointed2)))
          return true;
        if (not type->type_id)
          return (addr_pointed1 != addr_pointed2);
        else
          return areas_differ_with_type(process, state, addr_pointed1, snapshot1, region1, addr_pointed2, snapshot2,
                                        region2, type->subtype, pointer_level);
      } else {
        // TODO, We do not handle very well the case where
        // it belongs to a different (non-heap) region from the current one.

        return (addr_pointed1 != addr_pointed2);
      }
    }
    case DW_TAG_structure_type:
    case DW_TAG_class_type:
      for (const simgrid::mc::Member& member : type->members) {
        const void* member1             = simgrid::dwarf::resolve_member(real_area1, type, &member, &snapshot1);
        const void* member2             = simgrid::dwarf::resolve_member(real_area2, type, &member, &snapshot2);
        simgrid::mc::Region* subregion1 = snapshot1.get_region(member1, region1); // region1 is hinted
        simgrid::mc::Region* subregion2 = snapshot2.get_region(member2, region2); // region2 is hinted
        if (areas_differ_with_type(process, state, member1, snapshot1, subregion1, member2, snapshot2, subregion2,
                                   member.type, pointer_level))
          return true;
      }
      break;
    case DW_TAG_subroutine_type:
      return false;
    default:
      XBT_VERB("Unknown case: %d", type->type);
      break;
  }

  return false;
}

static bool global_variables_differ(const simgrid::mc::RemoteProcess& process, simgrid::mc::StateComparator& state,
                                    const simgrid::mc::ObjectInformation* object_info, simgrid::mc::Region* r1,
                                    simgrid::mc::Region* r2, const simgrid::mc::Snapshot& snapshot1,
                                    const simgrid::mc::Snapshot& snapshot2)
{
  xbt_assert(r1 && r2, "Missing region.");

  const std::vector<simgrid::mc::Variable>& variables = object_info->global_variables;

  for (simgrid::mc::Variable const& current_var : variables) {
    // If the variable is not in this object, skip it:
    // We do not expect to find a pointer to something which is not reachable
    // by the global variables.
    if ((char*)current_var.address < object_info->start_rw || (char*)current_var.address > object_info->end_rw)
      continue;

    const simgrid::mc::Type* bvariable_type = current_var.type;
    if (areas_differ_with_type(process, state, current_var.address, snapshot1, r1, current_var.address, snapshot2, r2,
                               bvariable_type, 0)) {
      XBT_VERB("Global variable %s (%p) is different between snapshots", current_var.name.c_str(), current_var.address);
      return true;
    }
  }

  return false;
}

static bool local_variables_differ(const simgrid::mc::RemoteProcess& process, simgrid::mc::StateComparator& state,
                                   const simgrid::mc::Snapshot& snapshot1, const simgrid::mc::Snapshot& snapshot2,
                                   const_mc_snapshot_stack_t stack1, const_mc_snapshot_stack_t stack2)
{
  if (stack1->local_variables.size() != stack2->local_variables.size()) {
    XBT_VERB("Different number of local variables");
    return true;
  }

  for (unsigned int cursor = 0; cursor < stack1->local_variables.size(); cursor++) {
    const_local_variable_t current_var1 = &stack1->local_variables[cursor];
    const_local_variable_t current_var2 = &stack2->local_variables[cursor];
    if (current_var1->name != current_var2->name || current_var1->subprogram != current_var2->subprogram ||
        current_var1->ip != current_var2->ip) {
      // TODO, fix current_varX->subprogram->name to include name if DW_TAG_inlined_subprogram
      XBT_VERB("Different name of variable (%s - %s) or frame (%s - %s) or ip (%lu - %lu)", current_var1->name.c_str(),
               current_var2->name.c_str(), current_var1->subprogram->name.c_str(),
               current_var2->subprogram->name.c_str(), current_var1->ip, current_var2->ip);
      return true;
    }

    if (areas_differ_with_type(process, state, current_var1->address, snapshot1,
                               snapshot1.get_region(current_var1->address), current_var2->address, snapshot2,
                               snapshot2.get_region(current_var2->address), current_var1->type, 0)) {
      XBT_VERB("Local variable %s (%p - %p) in frame %s is different between snapshots", current_var1->name.c_str(),
               current_var1->address, current_var2->address, current_var1->subprogram->name.c_str());
      return true;
    }
  }
  return false;
}

namespace simgrid {
namespace mc {

bool snapshot_equal(const Snapshot* s1, const Snapshot* s2)
{
  // TODO, make this a field of ModelChecker or something similar
  static StateComparator state_comparator;

  const RemoteProcess& process = mc_model_checker->get_remote_process();

  if (s1->hash_ != s2->hash_) {
    XBT_VERB("(%d - %d) Different hash: 0x%" PRIx64 "--0x%" PRIx64, s1->num_state_, s2->num_state_, s1->hash_,
             s2->hash_);
    return false;
  }
  XBT_VERB("(%d - %d) Same hash: 0x%" PRIx64, s1->num_state_, s2->num_state_, s1->hash_);

  /* Compare enabled processes */
  if (s1->enabled_processes_ != s2->enabled_processes_) {
    XBT_VERB("(%d - %d) Different amount of enabled processes", s1->num_state_, s2->num_state_);
    return false;
  }

  /* Compare size of stacks */
  for (unsigned long i = 0; i < s1->stacks_.size(); i++) {
    size_t size_used1 = s1->stack_sizes_[i];
    size_t size_used2 = s2->stack_sizes_[i];
    if (size_used1 != size_used2) {
      XBT_VERB("(%d - %d) Different size used in stacks: %zu - %zu", s1->num_state_, s2->num_state_, size_used1,
               size_used2);
      return false;
    }
  }

  /* Init heap information used in heap comparison algorithm */
  const s_xbt_mheap_t* heap1 = static_cast<xbt_mheap_t>(
      s1->read_bytes(alloca(sizeof(s_xbt_mheap_t)), sizeof(s_xbt_mheap_t), process.heap_address, ReadOptions::lazy()));
  const s_xbt_mheap_t* heap2 = static_cast<xbt_mheap_t>(
      s2->read_bytes(alloca(sizeof(s_xbt_mheap_t)), sizeof(s_xbt_mheap_t), process.heap_address, ReadOptions::lazy()));
  if (state_comparator.initHeapInformation(heap1, heap2, s1->to_ignore_, s2->to_ignore_) == -1) {
    XBT_VERB("(%d - %d) Different heap information", s1->num_state_, s2->num_state_);
    return false;
  }

  /* Stacks comparison */
  for (unsigned int cursor = 0; cursor < s1->stacks_.size(); cursor++) {
    const_mc_snapshot_stack_t stack1 = &s1->stacks_[cursor];
    const_mc_snapshot_stack_t stack2 = &s2->stacks_[cursor];

    if (local_variables_differ(process, state_comparator, *s1, *s2, stack1, stack2)) {
      XBT_VERB("(%d - %d) Different local variables between stacks %u", s1->num_state_, s2->num_state_, cursor + 1);
      return false;
    }
  }

  size_t regions_count = s1->snapshot_regions_.size();
  if (regions_count != s2->snapshot_regions_.size())
    return false;

  for (size_t k = 0; k != regions_count; ++k) {
    Region* region1 = s1->snapshot_regions_[k].get();
    Region* region2 = s2->snapshot_regions_[k].get();

    // Preconditions:
    if (region1->region_type() != RegionType::Data)
      continue;

    xbt_assert(region1->region_type() == region2->region_type());
    xbt_assert(region1->object_info() == region2->object_info());
    xbt_assert(region1->object_info());

    /* Compare global variables */
    if (global_variables_differ(process, state_comparator, region1->object_info(), region1, region2, *s1, *s2)) {
      std::string const& name = region1->object_info()->file_name;
      XBT_VERB("(%d - %d) Different global variables in %s", s1->num_state_, s2->num_state_, name.c_str());
      return false;
    }
  }

  /* Compare heap */
  if (mmalloc_heap_differ(process, state_comparator, *s1, *s2)) {
    XBT_VERB("(%d - %d) Different heap (mmalloc_compare)", s1->num_state_, s2->num_state_);
    return false;
  }

  XBT_VERB("(%d - %d) No difference found", s1->num_state_, s2->num_state_);

  return true;
}
} // namespace mc
} // namespace simgrid
