propagate.cpp

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/*******************************************************************\
 
Module: Propagate
 
Author: Daniel Kroening, dkr@amazon.com
 
\*******************************************************************/

 
#include "propagate.h"
 
#include <util/console.h>
#include <util/format_expr.h>
#include <util/simplify_expr.h>
 
#include "simplify_state_expr.h"
#include "state.h"
 
#include <iomanip>
#include <iostream>
 
void propagate(
  const std::vector<framet> &frames,
  const workt &work,
  const std::unordered_set<symbol_exprt, irep_hash> &address_taken,
  bool verbose,
  const namespacet &ns,
  const std::function<void(const symbol_exprt &, exprt, const workt::patht &)>
    &propagator)
{
  auto &f = frames[work.frame.index];
 
  if(verbose)
  {
    std::cout << '\n';
    std::cout << consolet::faint;
    std::cout << ' ' << std::setw(2) << work.frame.index << ' ';
    std::cout << consolet::reset << consolet::cyan << format(work.invariant);
    std::cout << consolet::reset << '\n';
  }
 
  for(const auto &implication : f.implications)
  {
    if(verbose)
    {
      std::cout << consolet::green;
      std::cout << 'C' << consolet::faint << std::setw(2) << work.frame.index
                << consolet::reset << ' ';
      std::cout << consolet::green << format(implication.as_expr());
      std::cout << consolet::reset << '\n';
    }
 
    auto &next_state = implication.rhs.arguments().front();
    auto lambda_expr = lambda_exprt({state_expr()}, work.invariant);
    auto instance = lambda_expr.instantiate({next_state});
    auto simplified1 = simplify_state_expr(instance, address_taken, ns);
    auto simplified1a = simplify_state_expr(simplified1, address_taken, ns);
    if(simplified1 != simplified1a)
    {
      std::cout << "SIMP0: " << format(instance) << "\n";
      std::cout << "SIMP1: " << format(simplified1) << "\n";
      std::cout << "SIMPa: " << format(simplified1a) << "\n";
      abort();
    }
 
    auto simplified2 = simplify_expr(simplified1, ns);
 
    if(implication.lhs.id() == ID_function_application)
    {
      // Sxx(ς) ⇒ Syy(ς[update])
      auto &state = to_symbol_expr(
        to_function_application_expr(implication.lhs).function());
      propagator(state, simplified2, work.path);
    }
    else if(
      implication.lhs.id() == ID_and &&
      to_and_expr(implication.lhs).op0().id() == ID_function_application)
    {
      // Sxx(ς) ∧ ς(COND) ⇒ Syy(ς)
      auto &function_application =
        to_function_application_expr(to_and_expr(implication.lhs).op0());
      auto &state = to_symbol_expr(function_application.function());
      auto cond1 = to_and_expr(implication.lhs).op1();
      auto cond2 = implies_exprt(cond1, simplified2);
      auto simplified = simplify_expr(cond2, ns);
      propagator(state, simplified, work.path);
    }
  }
}