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Symbolic state

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This commit is contained in:
Leonardo Alt
2020-04-06 12:27:53 +02:00
parent 0a72a3b8af
commit 05a85461fe
7 changed files with 169 additions and 80 deletions
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libsolidity/formal/EncodingContext.cpp
+2 -55
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@@ -25,13 +25,8 @@ using namespace solidity::util;
using namespace solidity::frontend::smt;
EncodingContext::EncodingContext():
m_thisAddress(make_unique<SymbolicAddressVariable>("this", *this))
m_state(*this)
{
auto sort = make_shared<ArraySort>(
SortProvider::intSort,
SortProvider::intSort
);
m_balances = make_unique<SymbolicVariable>(sort, "balances", *this);
}
void EncodingContext::reset()
@@ -39,8 +34,7 @@ void EncodingContext::reset()
resetAllVariables();
m_expressions.clear();
m_globalContext.clear();
m_thisAddress->resetIndex();
m_balances->resetIndex();
m_state.reset();
m_assertions.clear();
}
@@ -183,40 +177,6 @@ bool EncodingContext::knownGlobalSymbol(string const& _var) const
return m_globalContext.count(_var);
}
// Blockchain
Expression EncodingContext::thisAddress()
{
return m_thisAddress->currentValue();
}
Expression EncodingContext::balance()
{
return balance(m_thisAddress->currentValue());
}
Expression EncodingContext::balance(Expression _address)
{
return Expression::select(m_balances->currentValue(), move(_address));
}
void EncodingContext::transfer(Expression _from, Expression _to, Expression _value)
{
unsigned indexBefore = m_balances->index();
addBalance(_from, 0 - _value);
addBalance(_to, move(_value));
unsigned indexAfter = m_balances->index();
solAssert(indexAfter > indexBefore, "");
m_balances->increaseIndex();
/// Do not apply the transfer operation if _from == _to.
auto newBalances = Expression::ite(
move(_from) == move(_to),
m_balances->valueAtIndex(indexBefore),
m_balances->valueAtIndex(indexAfter)
);
addAssertion(m_balances->currentValue() == newBalances);
}
/// Solver.
Expression EncodingContext::assertions()
@@ -248,16 +208,3 @@ void EncodingContext::addAssertion(Expression const& _expr)
else
m_assertions.back() = _expr && move(m_assertions.back());
}
/// Private helpers.
void EncodingContext::addBalance(Expression _address, Expression _value)
{
auto newBalances = Expression::store(
m_balances->currentValue(),
_address,
balance(_address) + move(_value)
);
m_balances->increaseIndex();
addAssertion(newBalances == m_balances->currentValue());
}