skip_loops.cpp

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/*******************************************************************\
 
Module: Skip over selected loops by adding gotos
 
Author: Michael Tautschnig
 
Date: January 2016
 
\*******************************************************************/
 
 
#include "skip_loops.h"
 
#include <util/message.h>
#include <util/string2int.h>
 
#include <goto-programs/goto_model.h>
 
typedef std::set<unsigned> loop_idst;
typedef std::map<irep_idt, loop_idst> loop_mapt;
 
static bool skip_loops(
  goto_programt &goto_program,
  const loop_idst &loop_ids,
  messaget &message)
{
  loop_idst::const_iterator l_it=loop_ids.begin();
  Forall_goto_program_instructions(it, goto_program)
  {
    if(l_it==loop_ids.end())
      break;
    if(!it->is_backwards_goto())
      continue;
 
    const unsigned loop_id=it->loop_number;
    if(*l_it<loop_id)
      break; // error handled below
    if(*l_it>loop_id)
      continue;
 
    goto_programt::targett loop_head=it->get_target();
    goto_programt::targett next=it;
    ++next;
    assert(next!=goto_program.instructions.end());
 
    goto_program.insert_before(
      loop_head,
      goto_programt::make_goto(
        next, true_exprt(), loop_head->source_location()));
 
    ++l_it;
  }
  if(l_it!=loop_ids.end())
  {
    message.error() << "Loop " << *l_it << " not found"
                    << messaget::eom;
    return true;
  }
 
  return false;
}
 
static bool parse_loop_ids(
  const std::string &loop_ids,
  loop_mapt &loop_map)
{
  std::string::size_type length=loop_ids.length();
 
  for(std::string::size_type idx=0; idx<length; idx++)
  {
    std::string::size_type next=loop_ids.find(",", idx);
    std::string val=loop_ids.substr(idx, next-idx);
    std::string::size_type delim=val.rfind(".");
 
    if(delim==std::string::npos)
      return true;
 
    std::string fn=val.substr(0, delim);
    unsigned nr=safe_string2unsigned(val.substr(delim+1));
 
    loop_map[fn].insert(nr);
 
    if(next==std::string::npos)
      break;
    idx=next;
  }
 
  return false;
}
 
bool skip_loops(
  goto_modelt &goto_model,
  const std::string &loop_ids,
  message_handlert &message_handler)
{
  messaget message(message_handler);
 
  loop_mapt loop_map;
  if(parse_loop_ids(loop_ids, loop_map))
  {
    message.error() << "Failed to parse loop ids" << messaget::eom;
    return true;
  }
 
  loop_mapt::const_iterator it=loop_map.begin();
  for(auto &gf_entry : goto_model.goto_functions.function_map)
  {
    if(it == loop_map.end() || it->first < gf_entry.first)
      break; // possible error handled below
    else if(it->first == gf_entry.first)
    {
      if(skip_loops(gf_entry.second.body, it->second, message))
        return true;
      ++it;
    }
  }
  if(it!=loop_map.end())
  {
    message.error() << "No function " << it->first << " in goto program"
                    << messaget::eom;
    return true;
  }
 
  // update counters etc.
  goto_model.goto_functions.update();
 
  return false;
}