/* Copyright (c) 2004-2018. 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. */

#include <cstddef>
#include <cstdint>
#include <utility>

#include "xbt/asserts.h"
#include "xbt/sysdep.h"

#include <libunwind.h>

#include "src/mc/mc_dwarf.hpp"
#include "src/mc/ObjectInformation.hpp"
#include "src/mc/LocationList.hpp"

namespace simgrid {
namespace dwarf {

/** Resolve a location expression */
Location resolve(
                      simgrid::dwarf::DwarfExpression const& expression,
                      simgrid::mc::ObjectInformation* object_info,
                      unw_cursor_t * c,
                      void *frame_pointer_address,
                      simgrid::mc::AddressSpace* address_space, int process_index)
{
  simgrid::dwarf::ExpressionContext context;
  context.frame_base = frame_pointer_address;
  context.cursor = c;
  context.address_space = address_space;
  context.object_info = object_info;
  context.process_index = process_index;

  if (not expression.empty() && expression[0].atom >= DW_OP_reg0 && expression[0].atom <= DW_OP_reg31) {
    int dwarf_register = expression[0].atom - DW_OP_reg0;
    xbt_assert(c, "Missing frame context for register operation DW_OP_reg%i", dwarf_register);
    return Location(dwarf_register_to_libunwind(dwarf_register));
  }

  simgrid::dwarf::ExpressionStack stack;
  simgrid::dwarf::execute(expression, context, stack);
  return Location((void*) stack.top());
}

// TODO, move this in a method of LocationList
static simgrid::dwarf::DwarfExpression const* find_expression(
    simgrid::dwarf::LocationList const& locations, unw_word_t ip)
{
  for (simgrid::dwarf::LocationListEntry const& entry : locations)
    if (entry.valid_for_ip(ip))
      return &entry.expression();
  return nullptr;
}

Location resolve(
  simgrid::dwarf::LocationList const& locations,
  simgrid::mc::ObjectInformation* object_info,
  unw_cursor_t * c,
  void *frame_pointer_address,
  simgrid::mc::AddressSpace* address_space,
  int process_index)
{
  unw_word_t ip = 0;
  if (c && unw_get_reg(c, UNW_REG_IP, &ip))
    xbt_die("Could not resolve IP");
  simgrid::dwarf::DwarfExpression const* expression =
    find_expression(locations, ip);
  if (not expression)
    xbt_die("Could not resolve location");
  return simgrid::dwarf::resolve(
          *expression, object_info, c,
          frame_pointer_address, address_space, process_index);
}

LocationList location_list(
  simgrid::mc::ObjectInformation& info,
  Dwarf_Attribute& attr)
{
  LocationList locations;
  std::ptrdiff_t offset = 0;
  while (1) {
    Dwarf_Addr base;
    Dwarf_Addr start;
    Dwarf_Addr end;
    Dwarf_Op *ops;
    std::size_t len;

    offset = dwarf_getlocations(&attr, offset, &base, &start, &end, &ops, &len);

    if (offset == 0)
      break;
    else if (offset == -1)
      xbt_die("Error while loading location list");

    std::uint64_t base_address = (std::uint64_t) info.base_address();

    LocationListEntry::range_type range;
    if (start == 0)
      // If start == 0, this is not a location list:
      range = { 0, UINT64_MAX };
    else
      range =  { base_address + start, base_address + end };

    locations.push_back({ DwarfExpression(ops, ops+len), range });
  }

  return locations;
}
}
}
