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/********************* */
/*! \file bool_to_bv.cpp
** \verbatim
** Top contributors (to current version):
** Yoni Zohar, Makai Mann
** This file is part of the CVC4 project.
** Copyright (c) 2009-2018 by the authors listed in the file AUTHORS
** in the top-level source directory) and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief The BoolToBv preprocessing pass
**
**/
#include "preprocessing/passes/bool_to_bv.h"
#include <string>
#include <unordered_map>
#include <vector>
#include "expr/node.h"
#include "smt/smt_statistics_registry.h"
#include "theory/rewriter.h"
#include "theory/theory.h"
namespace CVC4 {
namespace preprocessing {
namespace passes {
using namespace CVC4::theory;
BoolToBV::BoolToBV(PreprocessingPassContext* preprocContext)
: PreprocessingPass(preprocContext, "bool-to-bv"),
d_lowerCache(),
d_one(bv::utils::mkOne(1)),
d_zero(bv::utils::mkZero(1)),
d_statistics(){};
PreprocessingPassResult BoolToBV::applyInternal(
AssertionPipeline* assertionsToPreprocess)
{
NodeManager::currentResourceManager()->spendResource(
options::preprocessStep());
std::vector<Node> new_assertions;
lowerBoolToBv(assertionsToPreprocess->ref(), new_assertions);
for (unsigned i = 0; i < assertionsToPreprocess->size(); ++i)
{
assertionsToPreprocess->replace(i, Rewriter::rewrite(new_assertions[i]));
}
return PreprocessingPassResult::NO_CONFLICT;
}
void BoolToBV::addToLowerCache(TNode term, Node new_term)
{
Assert(new_term != Node());
Assert(!hasLowerCache(term));
d_lowerCache[term] = new_term;
}
Node BoolToBV::getLowerCache(TNode term) const
{
Assert(hasLowerCache(term));
return d_lowerCache.find(term)->second;
}
bool BoolToBV::hasLowerCache(TNode term) const
{
return d_lowerCache.find(term) != d_lowerCache.end();
}
Node BoolToBV::lowerNode(TNode current, bool topLevel)
{
Node result;
NodeManager* nm = NodeManager::currentNM();
if (hasLowerCache(current))
{
result = getLowerCache(current);
}
else
{
if (current.getNumChildren() == 0)
{
if (current.getKind() == kind::CONST_BOOLEAN)
{
result = (current == bv::utils::mkTrue()) ? d_one : d_zero;
}
else
{
result = current;
}
}
else
{
Kind kind = current.getKind();
Kind new_kind = kind;
switch (kind)
{
case kind::EQUAL:
if (current[0].getType().isBitVector()
|| current[0].getType().isBoolean())
{
new_kind = kind::BITVECTOR_COMP;
}
break;
case kind::AND: new_kind = kind::BITVECTOR_AND; break;
case kind::OR: new_kind = kind::BITVECTOR_OR; break;
case kind::NOT: new_kind = kind::BITVECTOR_NOT; break;
case kind::XOR: new_kind = kind::BITVECTOR_XOR; break;
case kind::IMPLIES: new_kind = kind::BITVECTOR_OR; break;
case kind::ITE:
if (current.getType().isBitVector() || current.getType().isBoolean())
{
new_kind = kind::BITVECTOR_ITE;
}
break;
case kind::BITVECTOR_ULT: new_kind = kind::BITVECTOR_ULTBV; break;
case kind::BITVECTOR_SLT: new_kind = kind::BITVECTOR_SLTBV; break;
case kind::BITVECTOR_ULE:
case kind::BITVECTOR_UGT:
case kind::BITVECTOR_UGE:
case kind::BITVECTOR_SLE:
case kind::BITVECTOR_SGT:
case kind::BITVECTOR_SGE:
// Should have been removed by rewriting.
Unreachable();
default: break;
}
NodeBuilder<> builder(new_kind);
if (kind != new_kind)
{
++(d_statistics.d_numTermsLowered);
}
if (current.getMetaKind() == kind::metakind::PARAMETERIZED)
{
builder << current.getOperator();
}
Node converted;
if (new_kind == kind::ITE)
{
// Special-case ITE because need condition to be Boolean.
converted = lowerNode(current[0], true);
builder << converted;
converted = lowerNode(current[1]);
builder << converted;
converted = lowerNode(current[2]);
builder << converted;
}
else if (kind == kind::IMPLIES) {
// Special-case IMPLIES because needs to be rewritten.
converted = lowerNode(current[0]);
builder << nm->mkNode(kind::BITVECTOR_NOT, converted);
converted = lowerNode(current[1]);
builder << converted;
}
else
{
for (unsigned i = 0; i < current.getNumChildren(); ++i)
{
converted = lowerNode(current[i]);
builder << converted;
}
}
result = builder;
}
if (result.getType().isBoolean())
{
++(d_statistics.d_numTermsForcedLowered);
result = nm->mkNode(kind::ITE, result, d_one, d_zero);
}
addToLowerCache(current, result);
}
if (topLevel)
{
result = nm->mkNode(kind::EQUAL, result, d_one);
}
Assert(result != Node());
Debug("bool-to-bv") << "BoolToBV::lowerNode " << current << " => \n"
<< result << "\n";
return result;
}
void BoolToBV::lowerBoolToBv(const std::vector<Node>& assertions,
std::vector<Node>& new_assertions)
{
for (unsigned i = 0; i < assertions.size(); ++i)
{
Node new_assertion = lowerNode(assertions[i], true);
new_assertions.push_back(new_assertion);
Trace("bool-to-bv") << " " << assertions[i] << " => " << new_assertions[i]
<< "\n";
}
}
BoolToBV::Statistics::Statistics()
: d_numTermsLowered("preprocessing::passes::BoolToBV::NumTermsLowered", 0),
d_numAtomsLowered("preprocessing::passes::BoolToBV::NumAtomsLowered", 0),
d_numTermsForcedLowered(
"preprocessing::passes::BoolToBV::NumTermsForcedLowered", 0)
{
smtStatisticsRegistry()->registerStat(&d_numTermsLowered);
smtStatisticsRegistry()->registerStat(&d_numAtomsLowered);
smtStatisticsRegistry()->registerStat(&d_numTermsForcedLowered);
}
BoolToBV::Statistics::~Statistics()
{
smtStatisticsRegistry()->unregisterStat(&d_numTermsLowered);
smtStatisticsRegistry()->unregisterStat(&d_numAtomsLowered);
smtStatisticsRegistry()->unregisterStat(&d_numTermsForcedLowered);
}
} // namespace passes
} // namespace preprocessing
} // namespace CVC4
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