/*
This file is part of cpp-ethereum.
cpp-ethereum 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.
cpp-ethereum 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 cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Christian <c@ethdev.com>
* @date 2014
* Solidity AST to EVM bytecode compiler.
*/
#include <cassert>
#include <utility>
#include <libsolidity/AST.h>
#include <libsolidity/Compiler.h>
namespace dev {
namespace solidity {
void CompilerContext::setLabelPosition(uint32_t _label, uint32_t _position)
{
assert(m_labelPositions.find(_label) == m_labelPositions.end());
m_labelPositions[_label] = _position;
}
uint32_t CompilerContext::getLabelPosition(uint32_t _label) const
{
auto iter = m_labelPositions.find(_label);
assert(iter != m_labelPositions.end());
return iter->second;
}
void ExpressionCompiler::compile(Expression& _expression)
{
m_assemblyItems.clear();
_expression.accept(*this);
}
bytes ExpressionCompiler::getAssembledBytecode() const
{
bytes assembled;
assembled.reserve(m_assemblyItems.size());
// resolve label references
for (uint32_t pos = 0; pos < m_assemblyItems.size(); ++pos)
{
AssemblyItem const& item = m_assemblyItems[pos];
if (item.getType() == AssemblyItem::Type::LABEL)
m_context.setLabelPosition(item.getLabel(), pos + 1);
}
for (AssemblyItem const& item: m_assemblyItems)
if (item.getType() == AssemblyItem::Type::LABELREF)
assembled.push_back(m_context.getLabelPosition(item.getLabel()));
else
assembled.push_back(item.getData());
return assembled;
}
AssemblyItems ExpressionCompiler::compileExpression(CompilerContext& _context,
Expression& _expression)
{
ExpressionCompiler compiler(_context);
compiler.compile(_expression);
return compiler.getAssemblyItems();
}
void ExpressionCompiler::endVisit(Assignment& _assignment)
{
Expression& rightHandSide = _assignment.getRightHandSide();
Token::Value op = _assignment.getAssignmentOperator();
if (op != Token::ASSIGN)
{
// compound assignment
// @todo retrieve lvalue value
rightHandSide.accept(*this);
Type const& resultType = *_assignment.getType();
cleanHigherOrderBitsIfNeeded(*rightHandSide.getType(), resultType);
appendOrdinaryBinaryOperatorCode(Token::AssignmentToBinaryOp(op), resultType);
}
else
rightHandSide.accept(*this);
// @todo store value
}
void ExpressionCompiler::endVisit(UnaryOperation& _unaryOperation)
{
//@todo type checking and creating code for an operator should be in the same place:
// the operator should know how to convert itself and to which types it applies, so
// put this code together with "Type::acceptsBinary/UnaryOperator" into a class that
// represents the operator
switch (_unaryOperation.getOperator())
{
case Token::NOT: // !
append(eth::Instruction::NOT);
break;
case Token::BIT_NOT: // ~
append(eth::Instruction::BNOT);
break;
case Token::DELETE: // delete
// a -> a xor a (= 0).
// @todo this should also be an assignment
// @todo semantics change for complex types
append(eth::Instruction::DUP1);
append(eth::Instruction::XOR);
break;
case Token::INC: // ++ (pre- or postfix)
// @todo this should also be an assignment
if (_unaryOperation.isPrefixOperation())
{
append(eth::Instruction::PUSH1);
append(1);
append(eth::Instruction::ADD);
}
break;
case Token::DEC: // -- (pre- or postfix)
// @todo this should also be an assignment
if (_unaryOperation.isPrefixOperation())
{
append(eth::Instruction::PUSH1);
append(1);
append(eth::Instruction::SWAP1); //@todo avoid this
append(eth::Instruction::SUB);
}
break;
case Token::ADD: // +
// unary add, so basically no-op
break;
case Token::SUB: // -
// unary -x translates into "0-x"
append(eth::Instruction::PUSH1);
append(0);
append(eth::Instruction::SUB);
break;
default:
assert(false); // invalid operation
}
}
bool ExpressionCompiler::visit(BinaryOperation& _binaryOperation)
{
Expression& leftExpression = _binaryOperation.getLeftExpression();
Expression& rightExpression = _binaryOperation.getRightExpression();
Type const& resultType = *_binaryOperation.getType();
Token::Value const op = _binaryOperation.getOperator();
if (op == Token::AND || op == Token::OR)
{
// special case: short-circuiting
appendAndOrOperatorCode(_binaryOperation);
}
else if (Token::isCompareOp(op))
{
leftExpression.accept(*this);
rightExpression.accept(*this);
// the types to compare have to be the same, but the resulting type is always bool
assert(*leftExpression.getType() == *rightExpression.getType());
appendCompareOperatorCode(op, *leftExpression.getType());
}
else
{
leftExpression.accept(*this);
cleanHigherOrderBitsIfNeeded(*leftExpression.getType(), resultType);
rightExpression.accept(*this);
cleanHigherOrderBitsIfNeeded(*rightExpression.getType(), resultType);
appendOrdinaryBinaryOperatorCode(op, resultType);
}
// do not visit the child nodes, we already did that explicitly
return false;
}
void ExpressionCompiler::endVisit(FunctionCall& _functionCall)
{
if (_functionCall.isTypeConversion())
{
//@todo binary representation for all supported types (bool and int) is the same, so no-op
// here for now.
}
else
{
//@todo
}
}
void ExpressionCompiler::endVisit(MemberAccess&)
{
}
void ExpressionCompiler::endVisit(IndexAccess&)
{
}
void ExpressionCompiler::endVisit(Identifier&)
{
}
void ExpressionCompiler::endVisit(Literal& _literal)
{
switch (_literal.getType()->getCategory())
{
case Type::Category::INTEGER:
case Type::Category::BOOL:
{
bytes value = _literal.getType()->literalToBigEndian(_literal);
assert(value.size() <= 32);
assert(!value.empty());
append(static_cast<byte>(eth::Instruction::PUSH1) + static_cast<byte>(value.size() - 1));
append(value);
break;
}
default:
assert(false); // @todo
}
}
void ExpressionCompiler::cleanHigherOrderBitsIfNeeded(Type const& _typeOnStack, Type const& _targetType)
{
// If the type of one of the operands is extended, we need to remove all
// higher-order bits that we might have ignored in previous operations.
// @todo: store in the AST whether the operand might have "dirty" higher
// order bits
if (_typeOnStack == _targetType)
return;
if (_typeOnStack.getCategory() == Type::Category::INTEGER &&
_targetType.getCategory() == Type::Category::INTEGER)
{
//@todo
}
else
{
// If we get here, there is either an implementation missing to clean higher oder bits
// for non-integer types that are explicitly convertible or we got here in error.
assert(!_typeOnStack.isExplicitlyConvertibleTo(_targetType));
assert(false); // these types should not be convertible.
}
}
void ExpressionCompiler::appendAndOrOperatorCode(BinaryOperation& _binaryOperation)
{
Token::Value const op = _binaryOperation.getOperator();
assert(op == Token::OR || op == Token::AND);
_binaryOperation.getLeftExpression().accept(*this);
append(eth::Instruction::DUP1);
if (op == Token::AND)
append(eth::Instruction::NOT);
uint32_t endLabel = appendConditionalJump();
_binaryOperation.getRightExpression().accept(*this);
appendLabel(endLabel);
}
void ExpressionCompiler::appendCompareOperatorCode(Token::Value _operator, Type const& _type)
{
if (_operator == Token::EQ || _operator == Token::NE)
{
append(eth::Instruction::EQ);
if (_operator == Token::NE)
append(eth::Instruction::NOT);
}
else
{
IntegerType const* type = dynamic_cast<IntegerType const*>(&_type);
assert(type);
bool const isSigned = type->isSigned();
// note that EVM opcodes compare like "stack[0] < stack[1]",
// but our left value is at stack[1], so everyhing is reversed.
switch (_operator)
{
case Token::GTE:
append(isSigned ? eth::Instruction::SGT : eth::Instruction::GT);
append(eth::Instruction::NOT);
break;
case Token::LTE:
append(isSigned ? eth::Instruction::SLT : eth::Instruction::LT);
append(eth::Instruction::NOT);
break;
case Token::GT:
append(isSigned ? eth::Instruction::SLT : eth::Instruction::LT);
break;
case Token::LT:
append(isSigned ? eth::Instruction::SGT : eth::Instruction::GT);
break;
default:
assert(false);
}
}
}
void ExpressionCompiler::appendOrdinaryBinaryOperatorCode(Token::Value _operator, Type const& _type)
{
if (Token::isArithmeticOp(_operator))
appendArithmeticOperatorCode(_operator, _type);
else if (Token::isBitOp(_operator))
appendBitOperatorCode(_operator);
else if (Token::isShiftOp(_operator))
appendShiftOperatorCode(_operator);
else
assert(false); // unknown binary operator
}
void ExpressionCompiler::appendArithmeticOperatorCode(Token::Value _operator, Type const& _type)
{
IntegerType const* type = dynamic_cast<IntegerType const*>(&_type);
assert(type);
bool const isSigned = type->isSigned();
switch (_operator)
{
case Token::ADD:
append(eth::Instruction::ADD);
break;
case Token::SUB:
append(eth::Instruction::SWAP1);
append(eth::Instruction::SUB);
break;
case Token::MUL:
append(eth::Instruction::MUL);
break;
case Token::DIV:
append(isSigned ? eth::Instruction::SDIV : eth::Instruction::DIV);
break;
case Token::MOD:
append(isSigned ? eth::Instruction::SMOD : eth::Instruction::MOD);
break;
default:
assert(false);
}
}
void ExpressionCompiler::appendBitOperatorCode(Token::Value _operator)
{
switch (_operator)
{
case Token::BIT_OR:
append(eth::Instruction::OR);
break;
case Token::BIT_AND:
append(eth::Instruction::AND);
break;
case Token::BIT_XOR:
append(eth::Instruction::XOR);
break;
default:
assert(false);
}
}
void ExpressionCompiler::appendShiftOperatorCode(Token::Value _operator)
{
switch (_operator)
{
case Token::SHL:
assert(false); //@todo
break;
case Token::SAR:
assert(false); //@todo
break;
default:
assert(false);
}
}
uint32_t ExpressionCompiler::appendConditionalJump()
{
uint32_t label = m_context.dispenseNewLabel();
append(eth::Instruction::PUSH1);
appendLabelref(label);
append(eth::Instruction::JUMPI);
return label;
}
void ExpressionCompiler::append(bytes const& _data)
{
m_assemblyItems.reserve(m_assemblyItems.size() + _data.size());
for (byte b: _data)
append(b);
}
}
}
