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/********************* */
/*! \file bv_intro_pow2.cpp
** \verbatim
** Top contributors (to current version):
** Mathias Preiner, Liana Hadarean
** This file is part of the CVC4 project.
** Copyright (c) 2009-2021 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 BvIntroPow2 preprocessing pass
**
** Traverses the formula and applies the IsPowerOfTwo rewrite rule. This
** preprocessing pass is particularly useful on QF_BV/pspace benchmarks and
** can be enabled via option `--bv-intro-pow2`.
**/
#include "preprocessing/passes/bv_intro_pow2.h"
#include <unordered_map>
#include "preprocessing/assertion_pipeline.h"
#include "preprocessing/preprocessing_pass_context.h"
#include "theory/bv/theory_bv_rewrite_rules_simplification.h"
#include "theory/rewriter.h"
namespace CVC5 {
namespace preprocessing {
namespace passes {
using NodeMap = std::unordered_map<Node, Node, NodeHashFunction>;
using namespace CVC5::theory;
namespace {
Node pow2Rewrite(Node node, NodeMap& cache)
{
NodeMap::const_iterator ci = cache.find(node);
if (ci != cache.end())
{
Node incache = (*ci).second;
return incache.isNull() ? node : incache;
}
Node res = Node::null();
switch (node.getKind())
{
case kind::AND:
{
bool changed = false;
std::vector<Node> children;
for (unsigned i = 0, size = node.getNumChildren(); i < size; ++i)
{
Node child = node[i];
Node found = pow2Rewrite(child, cache);
changed = changed || (child != found);
children.push_back(found);
}
if (changed)
{
res = NodeManager::currentNM()->mkNode(kind::AND, children);
}
}
break;
case kind::EQUAL:
if (node[0].getType().isBitVector()
&& theory::bv::RewriteRule<theory::bv::IsPowerOfTwo>::applies(node))
{
res = theory::bv::RewriteRule<theory::bv::IsPowerOfTwo>::run<false>(node);
}
break;
default: break;
}
cache.insert(std::make_pair(node, res));
return res.isNull() ? node : res;
}
} // namespace
BvIntroPow2::BvIntroPow2(PreprocessingPassContext* preprocContext)
: PreprocessingPass(preprocContext, "bv-intro-pow2"){};
PreprocessingPassResult BvIntroPow2::applyInternal(
AssertionPipeline* assertionsToPreprocess)
{
std::unordered_map<Node, Node, NodeHashFunction> cache;
for (unsigned i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
{
Node cur = (*assertionsToPreprocess)[i];
Node res = pow2Rewrite(cur, cache);
if (res != cur)
{
res = Rewriter::rewrite(res);
assertionsToPreprocess->replace(i, res);
}
}
return PreprocessingPassResult::NO_CONFLICT;
}
} // namespace passes
} // namespace preprocessing
} // namespace CVC5
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