Add mini-interpreter to check representation.

This commit is contained in:
chriseth 2019-05-20 16:23:59 +02:00
parent 1c16124a09
commit cee1340113
3 changed files with 72 additions and 14 deletions

View File

@ -91,6 +91,20 @@ inline u256 s2u(s256 _u)
return u256(c_end + _u);
}
inline u256 exp256(u256 _base, u256 _exponent)
{
using boost::multiprecision::limb_type;
u256 result = 1;
while (_exponent)
{
if (boost::multiprecision::bit_test(_exponent, 0))
result *= _base;
_base *= _base;
_exponent >>= 1;
}
return result;
}
inline std::ostream& operator<<(std::ostream& os, bytes const& _bytes)
{
std::ostringstream ss;

View File

@ -35,6 +35,63 @@ using namespace yul;
using Representation = ConstantOptimiser::Representation;
namespace
{
struct MiniEVMInterpreter: boost::static_visitor<u256>
{
explicit MiniEVMInterpreter(EVMDialect const& _dialect): m_dialect(_dialect) {}
u256 eval(Expression const& _expr)
{
return boost::apply_visitor(*this, _expr);
}
u256 eval(dev::eth::Instruction _instr, vector<Expression> const& _arguments)
{
vector<u256> args;
for (auto const& arg: _arguments)
args.emplace_back(eval(arg));
switch (_instr)
{
case eth::Instruction::ADD:
return args.at(0) + args.at(1);
case eth::Instruction::SUB:
return args.at(0) - args.at(1);
case eth::Instruction::MUL:
return args.at(0) * args.at(1);
case eth::Instruction::EXP:
return exp256(args.at(0), args.at(1));
case eth::Instruction::SHL:
return args.at(0) > 255 ? 0 : (args.at(1) << unsigned(args.at(0)));
case eth::Instruction::NOT:
return ~args.at(0);
default:
yulAssert(false, "Invalid operation generated in constant optimizer.");
}
return 0;
}
u256 operator()(FunctionalInstruction const& _instr)
{
return eval(_instr.instruction, _instr.arguments);
}
u256 operator()(FunctionCall const& _funCall)
{
BuiltinFunctionForEVM const* fun = m_dialect.builtin(_funCall.functionName.name);
yulAssert(fun, "Expected builtin function.");
yulAssert(fun->instruction, "Expected EVM instruction.");
return eval(*fun->instruction, _funCall.arguments);
}
u256 operator()(Literal const& _literal)
{
return valueOfLiteral(_literal);
}
u256 operator()(Identifier const&) { yulAssert(false, ""); }
EVMDialect const& m_dialect;
};
}
void ConstantOptimiser::visit(Expression& _e)
{
if (_e.type() == typeid(Literal))
@ -118,6 +175,7 @@ Representation const& RepresentationFinder::findRepresentation(dev::u256 const&
m_maxSteps--;
routine = min(move(routine), move(newRoutine));
}
yulAssert(MiniEVMInterpreter{m_dialect}.eval(*routine.expression) == _value, "Invalid expression generated.");
return m_cache[_value] = move(routine);
}

View File

@ -37,20 +37,6 @@ using namespace yul::test;
namespace
{
u256 exp256(u256 _base, u256 _exponent)
{
using boost::multiprecision::limb_type;
u256 result = 1;
while (_exponent)
{
if (boost::multiprecision::bit_test(_exponent, 0))
result *= _base;
_base *= _base;
_exponent >>= 1;
}
return result;
}
/// Reads 32 bytes from @a _data at position @a _offset bytes while
/// interpreting @a _data to be padded with an infinite number of zero
/// bytes beyond its end.