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Merge pull request #4351 from ethereum/smt_portfolio

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[SMTChecker] SMTPortfolio: use all SMT solvers available
This commit is contained in:
Alex Beregszaszi 2018-07-27 17:07:56 +01:00 committed by GitHub
commit 2794a22d84
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GPG Key ID: 4AEE18F83AFDEB23
11 changed files with 269 additions and 59 deletions
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29
libsolidity/CMakeLists.txt
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@ -7,24 +7,27 @@ if (${Z3_FOUND})
include_directories(${Z3_INCLUDE_DIR})
add_definitions(-DHAVE_Z3)
message("Z3 SMT solver found. This enables optional SMT checking with Z3.")
list(REMOVE_ITEM sources "${CMAKE_CURRENT_SOURCE_DIR}/formal/CVC4Interface.cpp")
else()
list(REMOVE_ITEM sources "${CMAKE_CURRENT_SOURCE_DIR}/formal/Z3Interface.cpp")
find_package(GMP QUIET)
find_package(CVC4 QUIET)
if (${CVC4_FOUND})
if (${GMP_FOUND})
include_directories(${CVC4_INCLUDE_DIR})
add_definitions(-DHAVE_CVC4)
message("CVC4 SMT solver and GMP found. This enables optional SMT checking with CVC4.")
else()
message("CVC4 SMT solver found but its dependency GMP was NOT found. Optional SMT checking with CVC4 will not be available. Please install GMP if it is desired.")
list(REMOVE_ITEM sources "${CMAKE_CURRENT_SOURCE_DIR}/formal/CVC4Interface.cpp")
endif()
endif()
find_package(GMP QUIET)
find_package(CVC4 QUIET)
if (${CVC4_FOUND})
if (${GMP_FOUND})
include_directories(${CVC4_INCLUDE_DIR})
add_definitions(-DHAVE_CVC4)
message("CVC4 SMT solver and GMP found. This enables optional SMT checking with CVC4.")
else()
message("No SMT solver found (Z3 or CVC4). Optional SMT checking will not be available. Please install Z3 or CVC4 if it is desired.")
message("CVC4 SMT solver found but its dependency GMP was NOT found. Optional SMT checking with CVC4 will not be available. Please install GMP if it is desired.")
list(REMOVE_ITEM sources "${CMAKE_CURRENT_SOURCE_DIR}/formal/CVC4Interface.cpp")
endif()
else()
list(REMOVE_ITEM sources "${CMAKE_CURRENT_SOURCE_DIR}/formal/CVC4Interface.cpp")
endif()
if (NOT (${Z3_FOUND} OR ${CVC4_FOUND}))
message("No SMT solver found. Optional SMT checking will not be available. Please install Z3 or CVC4 if it is desired.")
endif()
add_library(solidity ${sources} ${headers})

9
libsolidity/formal/CVC4Interface.cpp
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@ -50,23 +50,20 @@ void CVC4Interface::pop()
m_solver.pop();
}
Expression CVC4Interface::newFunction(string _name, Sort _domain, Sort _codomain)
void CVC4Interface::declareFunction(string _name, Sort _domain, Sort _codomain)
{
CVC4::Type fType = m_context.mkFunctionType(cvc4Sort(_domain), cvc4Sort(_codomain));
m_functions.insert({_name, m_context.mkVar(_name.c_str(), fType)});
return SolverInterface::newFunction(move(_name), _domain, _codomain);
}
Expression CVC4Interface::newInteger(string _name)
void CVC4Interface::declareInteger(string _name)
{
m_constants.insert({_name, m_context.mkVar(_name.c_str(), m_context.integerType())});
return SolverInterface::newInteger(move(_name));
}
Expression CVC4Interface::newBool(string _name)
void CVC4Interface::declareBool(string _name)
{
m_constants.insert({_name, m_context.mkVar(_name.c_str(), m_context.booleanType())});
return SolverInterface::newBool(std::move(_name));
}
void CVC4Interface::addAssertion(Expression const& _expr)

6
libsolidity/formal/CVC4Interface.h
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@ -40,9 +40,9 @@ public:
void push() override;
void pop() override;
Expression newFunction(std::string _name, Sort _domain, Sort _codomain) override;
Expression newInteger(std::string _name) override;
Expression newBool(std::string _name) override;
void declareFunction(std::string _name, Sort _domain, Sort _codomain) override;
void declareInteger(std::string _name) override;
void declareBool(std::string _name) override;
void addAssertion(Expression const& _expr) override;
std::pair<CheckResult, std::vector<std::string>> check(std::vector<Expression> const& _expressionsToEvaluate) override;

22
libsolidity/formal/SMTChecker.cpp
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@ -17,13 +17,7 @@
#include <libsolidity/formal/SMTChecker.h>
#ifdef HAVE_Z3
#include <libsolidity/formal/Z3Interface.h>
#elif HAVE_CVC4
#include <libsolidity/formal/CVC4Interface.h>
#else
#include <libsolidity/formal/SMTLib2Interface.h>
#endif
#include <libsolidity/formal/SMTPortfolio.h>
#include <libsolidity/formal/SSAVariable.h>
#include <libsolidity/formal/SymbolicIntVariable.h>
@ -39,16 +33,9 @@ using namespace dev;
using namespace dev::solidity;
SMTChecker::SMTChecker(ErrorReporter& _errorReporter, ReadCallback::Callback const& _readFileCallback):
#ifdef HAVE_Z3
m_interface(make_shared<smt::Z3Interface>()),
#elif HAVE_CVC4
m_interface(make_shared<smt::CVC4Interface>()),
#else
m_interface(make_shared<smt::SMTLib2Interface>(_readFileCallback)),
#endif
m_interface(make_shared<smt::SMTPortfolio>(_readFileCallback)),
m_errorReporter(_errorReporter)
{
(void)_readFileCallback;
}
void SMTChecker::analyze(SourceUnit const& _source)
@ -630,6 +617,9 @@ void SMTChecker::checkCondition(
case smt::CheckResult::UNKNOWN:
m_errorReporter.warning(_location, _description + " might happen here." + loopComment);
break;
case smt::CheckResult::CONFLICTING:
m_errorReporter.warning(_location, "At least two SMT solvers provided conflicting answers. Results might not be sound.");
break;
case smt::CheckResult::ERROR:
m_errorReporter.warning(_location, "Error trying to invoke SMT solver.");
break;
@ -657,6 +647,8 @@ void SMTChecker::checkBooleanNotConstant(Expression const& _condition, string co
if (positiveResult == smt::CheckResult::ERROR || negatedResult == smt::CheckResult::ERROR)
m_errorReporter.warning(_condition.location(), "Error trying to invoke SMT solver.");
else if (positiveResult == smt::CheckResult::CONFLICTING || negatedResult == smt::CheckResult::CONFLICTING)
m_errorReporter.warning(_condition.location(), "At least two SMT solvers provided conflicting answers. Results might not be sound.");
else if (positiveResult == smt::CheckResult::SATISFIABLE && negatedResult == smt::CheckResult::SATISFIABLE)
{
// everything fine.

9
libsolidity/formal/SMTLib2Interface.cpp
View File

@ -62,7 +62,7 @@ void SMTLib2Interface::pop()
m_accumulatedOutput.pop_back();
}
Expression SMTLib2Interface::newFunction(string _name, Sort _domain, Sort _codomain)
void SMTLib2Interface::declareFunction(string _name, Sort _domain, Sort _codomain)
{
write(
"(declare-fun |" +
@ -73,19 +73,16 @@ Expression SMTLib2Interface::newFunction(string _name, Sort _domain, Sort _codom
(_codomain == Sort::Int ? "Int" : "Bool") +
")"
);
return SolverInterface::newFunction(move(_name), _domain, _codomain);
}
Expression SMTLib2Interface::newInteger(string _name)
void SMTLib2Interface::declareInteger(string _name)
{
write("(declare-const |" + _name + "| Int)");
return SolverInterface::newInteger(move(_name));
}
Expression SMTLib2Interface::newBool(string _name)
void SMTLib2Interface::declareBool(string _name)
{
write("(declare-const |" + _name + "| Bool)");
return SolverInterface::newBool(std::move(_name));
}
void SMTLib2Interface::addAssertion(Expression const& _expr)

6
libsolidity/formal/SMTLib2Interface.h
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@ -48,9 +48,9 @@ public:
void push() override;
void pop() override;
Expression newFunction(std::string _name, Sort _domain, Sort _codomain) override;
Expression newInteger(std::string _name) override;
Expression newBool(std::string _name) override;
void declareFunction(std::string _name, Sort _domain, Sort _codomain) override;
void declareInteger(std::string _name) override;
void declareBool(std::string _name) override;
void addAssertion(Expression const& _expr) override;
std::pair<CheckResult, std::vector<std::string>> check(std::vector<Expression> const& _expressionsToEvaluate) override;

151
libsolidity/formal/SMTPortfolio.cpp Normal file
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@ -0,0 +1,151 @@
/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libsolidity/formal/SMTPortfolio.h>
#ifdef HAVE_Z3
#include <libsolidity/formal/Z3Interface.h>
#endif
#ifdef HAVE_CVC4
#include <libsolidity/formal/CVC4Interface.h>
#endif
#if !defined (HAVE_Z3) && !defined (HAVE_CVC4)
#include <libsolidity/formal/SMTLib2Interface.h>
#endif
using namespace std;
using namespace dev;
using namespace dev::solidity::smt;
SMTPortfolio::SMTPortfolio(ReadCallback::Callback const& _readCallback)
{
#ifdef HAVE_Z3
m_solvers.emplace_back(make_shared<smt::Z3Interface>());
#endif
#ifdef HAVE_CVC4
m_solvers.emplace_back(make_shared<smt::CVC4Interface>());
#endif
#if !defined (HAVE_Z3) && !defined (HAVE_CVC4)
m_solvers.emplace_back(make_shared<smt::SMTLib2Interface>(_readCallback)),
#endif
(void)_readCallback;
}
void SMTPortfolio::reset()
{
for (auto s : m_solvers)
s->reset();
}
void SMTPortfolio::push()
{
for (auto s : m_solvers)
s->push();
}
void SMTPortfolio::pop()
{
for (auto s : m_solvers)
s->pop();
}
void SMTPortfolio::declareFunction(string _name, Sort _domain, Sort _codomain)
{
for (auto s : m_solvers)
s->declareFunction(_name, _domain, _codomain);
}
void SMTPortfolio::declareInteger(string _name)
{
for (auto s : m_solvers)
s->declareInteger(_name);
}
void SMTPortfolio::declareBool(string _name)
{
for (auto s : m_solvers)
s->declareBool(_name);
}
void SMTPortfolio::addAssertion(Expression const& _expr)
{
for (auto s : m_solvers)
s->addAssertion(_expr);
}
/*
* Broadcasts the SMT query to all solvers and returns a single result.
* This comment explains how this result is decided.
*
* When a solver is queried, there are four possible answers:
* SATISFIABLE (SAT), UNSATISFIABLE (UNSAT), UNKNOWN, CONFLICTING, ERROR
* We say that a solver _answered_ the query if it returns either:
* SAT or UNSAT
* A solver did not answer the query if it returns either:
* UNKNOWN (it tried but couldn't solve it) or ERROR (crash, internal error, API error, etc).
*
* Ideally all solvers answer the query and agree on what the answer is
* (all say SAT or all say UNSAT).
*
* The actual logic as as follows:
* 1) If at least one solver answers the query, all the non-answer results are ignored.
* Here SAT/UNSAT is preferred over UNKNOWN since it's an actual answer, and over ERROR
* because one buggy solver/integration shouldn't break the portfolio.
*
* 2) If at least one solver answers SAT and at least one answers UNSAT, at least one of them is buggy
* and the result is CONFLICTING.
* In the future if we have more than 2 solvers enabled we could go with the majority.
*
* 3) If NO solver answers the query:
* If at least one solver returned UNKNOWN (where the rest returned ERROR), the result is UNKNOWN.
* This is preferred over ERROR since the SMTChecker might decide to abstract the query
* when it is told that this is a hard query to solve.
*
* If all solvers return ERROR, the result is ERROR.
*/
pair<CheckResult, vector<string>> SMTPortfolio::check(vector<Expression> const& _expressionsToEvaluate)
{
CheckResult lastResult = CheckResult::ERROR;
vector<string> finalValues;
for (auto s : m_solvers)
{
CheckResult result;
vector<string> values;
tie(result, values) = s->check(_expressionsToEvaluate);
if (solverAnswered(result))
{
if (!solverAnswered(lastResult))
{
lastResult = result;
finalValues = std::move(values);
}
else if (lastResult != result)
{
lastResult = CheckResult::CONFLICTING;
break;
}
}
else if (result == CheckResult::UNKNOWN && lastResult == CheckResult::ERROR)
lastResult = result;
}
return make_pair(lastResult, finalValues);
}
bool SMTPortfolio::solverAnswered(CheckResult result)
{
return result == CheckResult::SATISFIABLE || result == CheckResult::UNSATISFIABLE;
}

67
libsolidity/formal/SMTPortfolio.h Normal file
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@ -0,0 +1,67 @@
/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <libsolidity/formal/SolverInterface.h>
#include <libsolidity/interface/ReadFile.h>
#include <boost/noncopyable.hpp>
#include <vector>
namespace dev
{
namespace solidity
{
namespace smt
{
/**
* The SMTPortfolio wraps all available solvers within a single interface,
* propagating the functionalities to all solvers.
* It also checks whether different solvers give conflicting answers
* to SMT queries.
*/
class SMTPortfolio: public SolverInterface, public boost::noncopyable
{
public:
SMTPortfolio(ReadCallback::Callback const& _readCallback);
void reset() override;
void push() override;
void pop() override;
void declareFunction(std::string _name, Sort _domain, Sort _codomain) override;
void declareInteger(std::string _name) override;
void declareBool(std::string _name) override;
void addAssertion(Expression const& _expr) override;
std::pair<CheckResult, std::vector<std::string>> check(std::vector<Expression> const& _expressionsToEvaluate) override;
private:
static bool solverAnswered(CheckResult result);
std::vector<std::shared_ptr<smt::SolverInterface>> m_solvers;
};
}
}
}

14
libsolidity/formal/SolverInterface.h
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@ -39,7 +39,7 @@ namespace smt
enum class CheckResult
{
SATISFIABLE, UNSATISFIABLE, UNKNOWN, ERROR
SATISFIABLE, UNSATISFIABLE, UNKNOWN, CONFLICTING, ERROR
};
enum class Sort
@ -199,8 +199,10 @@ public:
virtual void push() = 0;
virtual void pop() = 0;
virtual Expression newFunction(std::string _name, Sort _domain, Sort _codomain)
virtual void declareFunction(std::string _name, Sort _domain, Sort _codomain) = 0;
Expression newFunction(std::string _name, Sort _domain, Sort _codomain)
{
declareFunction(_name, _domain, _codomain);
solAssert(_domain == Sort::Int, "Function sort not supported.");
// Subclasses should do something here
switch (_codomain)
@ -214,14 +216,18 @@ public:
break;
}
}
virtual Expression newInteger(std::string _name)
virtual void declareInteger(std::string _name) = 0;
Expression newInteger(std::string _name)
{
// Subclasses should do something here
declareInteger(_name);
return Expression(std::move(_name), {}, Sort::Int);
}
virtual Expression newBool(std::string _name)
virtual void declareBool(std::string _name) = 0;
Expression newBool(std::string _name)
{
// Subclasses should do something here
declareBool(_name);
return Expression(std::move(_name), {}, Sort::Bool);
}

9
libsolidity/formal/Z3Interface.cpp
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@ -51,22 +51,19 @@ void Z3Interface::pop()
m_solver.pop();
}
Expression Z3Interface::newFunction(string _name, Sort _domain, Sort _codomain)
void Z3Interface::declareFunction(string _name, Sort _domain, Sort _codomain)
{
m_functions.insert({_name, m_context.function(_name.c_str(), z3Sort(_domain), z3Sort(_codomain))});
return SolverInterface::newFunction(move(_name), _domain, _codomain);
}
Expression Z3Interface::newInteger(string _name)
void Z3Interface::declareInteger(string _name)
{
m_constants.insert({_name, m_context.int_const(_name.c_str())});
return SolverInterface::newInteger(move(_name));
}
Expression Z3Interface::newBool(string _name)
void Z3Interface::declareBool(string _name)
{
m_constants.insert({_name, m_context.bool_const(_name.c_str())});
return SolverInterface::newBool(std::move(_name));
}
void Z3Interface::addAssertion(Expression const& _expr)

6
libsolidity/formal/Z3Interface.h
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@ -40,9 +40,9 @@ public:
void push() override;
void pop() override;
Expression newFunction(std::string _name, Sort _domain, Sort _codomain) override;
Expression newInteger(std::string _name) override;
Expression newBool(std::string _name) override;
void declareFunction(std::string _name, Sort _domain, Sort _codomain) override;
void declareInteger(std::string _name) override;
void declareBool(std::string _name) override;
void addAssertion(Expression const& _expr) override;
std::pair<CheckResult, std::vector<std::string>> check(std::vector<Expression> const& _expressionsToEvaluate) override;