/*
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 for expressions.
*/
#include <utility>
#include <numeric>
#include <libdevcore/Common.h>
#include <libsolidity/AST.h>
#include <libsolidity/ExpressionCompiler.h>
#include <libsolidity/CompilerContext.h>
using namespace std;
namespace dev {
namespace solidity {
void ExpressionCompiler::compileExpression(CompilerContext& _context, Expression& _expression)
{
ExpressionCompiler compiler(_context);
_expression.accept(compiler);
}
void ExpressionCompiler::appendTypeConversion(CompilerContext& _context,
Type const& _typeOnStack, Type const& _targetType)
{
ExpressionCompiler compiler(_context);
compiler.appendTypeConversion(_typeOnStack, _targetType);
}
bool ExpressionCompiler::visit(Assignment& _assignment)
{
_assignment.getRightHandSide().accept(*this);
appendTypeConversion(*_assignment.getRightHandSide().getType(), *_assignment.getType());
_assignment.getLeftHandSide().accept(*this);
if (asserts(m_currentLValue.isValid()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("LValue not retrieved."));
Token::Value op = _assignment.getAssignmentOperator();
if (op != Token::ASSIGN) // compound assignment
{
if (m_currentLValue.storesReferenceOnStack())
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
m_currentLValue.retrieveValue(_assignment, true);
appendOrdinaryBinaryOperatorCode(Token::AssignmentToBinaryOp(op), *_assignment.getType());
}
m_currentLValue.storeValue(_assignment);
m_currentLValue.reset();
return false;
}
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: // !
m_context << eth::Instruction::ISZERO;
break;
case Token::BIT_NOT: // ~
m_context << eth::Instruction::NOT;
break;
case Token::DELETE: // delete
// @todo semantics change for complex types
if (asserts(m_currentLValue.isValid()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("LValue not retrieved."));
m_context << u256(0);
if (m_currentLValue.storesReferenceOnStack())
m_context << eth::Instruction::SWAP1;
m_currentLValue.storeValue(_unaryOperation);
m_currentLValue.reset();
break;
case Token::INC: // ++ (pre- or postfix)
case Token::DEC: // -- (pre- or postfix)
if (asserts(m_currentLValue.isValid()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("LValue not retrieved."));
m_currentLValue.retrieveValue(_unaryOperation);
if (!_unaryOperation.isPrefixOperation())
{
if (m_currentLValue.storesReferenceOnStack())
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
else
m_context << eth::Instruction::DUP1;
}
m_context << u256(1);
if (_unaryOperation.getOperator() == Token::INC)
m_context << eth::Instruction::ADD;
else
m_context << eth::Instruction::SWAP1 << eth::Instruction::SUB; // @todo avoid the swap
// Stack for prefix: [ref] (*ref)+-1
// Stack for postfix: *ref [ref] (*ref)+-1
if (m_currentLValue.storesReferenceOnStack())
m_context << eth::Instruction::SWAP1;
m_currentLValue.storeValue(_unaryOperation, !_unaryOperation.isPrefixOperation());
m_currentLValue.reset();
break;
case Token::ADD: // +
// unary add, so basically no-op
break;
case Token::SUB: // -
m_context << u256(0) << eth::Instruction::SUB;
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Invalid unary operator: " +
string(Token::toString(_unaryOperation.getOperator()))));
}
}
bool ExpressionCompiler::visit(BinaryOperation& _binaryOperation)
{
Expression& leftExpression = _binaryOperation.getLeftExpression();
Expression& rightExpression = _binaryOperation.getRightExpression();
Type const& commonType = _binaryOperation.getCommonType();
Token::Value const op = _binaryOperation.getOperator();
if (op == Token::AND || op == Token::OR) // special case: short-circuiting
appendAndOrOperatorCode(_binaryOperation);
else
{
bool cleanupNeeded = false;
if (commonType.getCategory() == Type::Category::INTEGER)
if (Token::isCompareOp(op) || op == Token::DIV || op == Token::MOD)
cleanupNeeded = true;
rightExpression.accept(*this);
appendTypeConversion(*rightExpression.getType(), commonType, cleanupNeeded);
leftExpression.accept(*this);
appendTypeConversion(*leftExpression.getType(), commonType, cleanupNeeded);
if (Token::isCompareOp(op))
appendCompareOperatorCode(op, commonType);
else
appendOrdinaryBinaryOperatorCode(op, commonType);
}
// do not visit the child nodes, we already did that explicitly
return false;
}
bool ExpressionCompiler::visit(FunctionCall& _functionCall)
{
if (_functionCall.isTypeConversion())
{
//@todo we only have integers and bools for now which cannot be explicitly converted
if (asserts(_functionCall.getArguments().size() == 1))
BOOST_THROW_EXCEPTION(InternalCompilerError());
Expression& firstArgument = *_functionCall.getArguments().front();
firstArgument.accept(*this);
appendTypeConversion(*firstArgument.getType(), *_functionCall.getType());
}
else
{
// Calling convention: Caller pushes return address and arguments
// Callee removes them and pushes return values
FunctionDefinition const& function = dynamic_cast<FunctionType const&>(*_functionCall.getExpression().getType()).getFunction();
eth::AssemblyItem returnLabel = m_context.pushNewTag();
std::vector<ASTPointer<Expression>> const& arguments = _functionCall.getArguments();
if (asserts(arguments.size() == function.getParameters().size()))
BOOST_THROW_EXCEPTION(InternalCompilerError());
for (unsigned i = 0; i < arguments.size(); ++i)
{
arguments[i]->accept(*this);
appendTypeConversion(*arguments[i]->getType(), *function.getParameters()[i]->getType());
}
_functionCall.getExpression().accept(*this);
if (asserts(m_currentLValue.isInCode()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Code reference expected."));
m_currentLValue.reset();
m_context.appendJump();
m_context << returnLabel;
// callee adds return parameters, but removes arguments and return label
m_context.adjustStackOffset(function.getReturnParameters().size() - arguments.size() - 1);
// @todo for now, the return value of a function is its first return value, so remove
// all others
for (unsigned i = 1; i < function.getReturnParameters().size(); ++i)
m_context << eth::Instruction::POP;
}
return false;
}
void ExpressionCompiler::endVisit(MemberAccess& _memberAccess)
{
if (asserts(m_currentLValue.isInStorage()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Member access to a non-storage value."));
StructType const& type = dynamic_cast<StructType const&>(*_memberAccess.getExpression().getType());
unsigned memberIndex = type.memberNameToIndex(_memberAccess.getMemberName());
if (asserts(memberIndex <= type.getMemberCount()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Member not found in struct during compilation."));
m_context << type.getStorageOffsetOfMember(memberIndex) << eth::Instruction::ADD;
m_currentLValue.retrieveValueIfLValueNotRequested(_memberAccess);
}
bool ExpressionCompiler::visit(IndexAccess& _indexAccess)
{
m_currentLValue.reset();
_indexAccess.getBaseExpression().accept(*this);
if (asserts(m_currentLValue.isInStorage()))
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Index access to a non-storage value."));
_indexAccess.getIndexExpression().accept(*this);
appendTypeConversion(*_indexAccess.getIndexExpression().getType(),
*dynamic_cast<MappingType const&>(*_indexAccess.getBaseExpression().getType()).getKeyType(),
true);
// @todo move this once we actually use memory
m_context << u256(32) << eth::Instruction::MSTORE << u256(0) << eth::Instruction::MSTORE;
m_context << u256(64) << u256(0) << eth::Instruction::SHA3;
m_currentLValue = LValue(m_context, LValue::STORAGE);
m_currentLValue.retrieveValueIfLValueNotRequested(_indexAccess);
return false;
}
void ExpressionCompiler::endVisit(Identifier& _identifier)
{
m_currentLValue.fromDeclaration(_identifier, *_identifier.getReferencedDeclaration());
m_currentLValue.retrieveValueIfLValueNotRequested(_identifier);
}
void ExpressionCompiler::endVisit(Literal& _literal)
{
switch (_literal.getType()->getCategory())
{
case Type::Category::INTEGER:
case Type::Category::BOOL:
m_context << _literal.getType()->literalValue(_literal);
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Only integer and boolean literals implemented for now."));
}
}
void ExpressionCompiler::appendAndOrOperatorCode(BinaryOperation& _binaryOperation)
{
Token::Value const op = _binaryOperation.getOperator();
if (asserts(op == Token::OR || op == Token::AND))
BOOST_THROW_EXCEPTION(InternalCompilerError());
_binaryOperation.getLeftExpression().accept(*this);
m_context << eth::Instruction::DUP1;
if (op == Token::AND)
m_context << eth::Instruction::ISZERO;
eth::AssemblyItem endLabel = m_context.appendConditionalJump();
m_context << eth::Instruction::POP;
_binaryOperation.getRightExpression().accept(*this);
m_context << endLabel;
}
void ExpressionCompiler::appendCompareOperatorCode(Token::Value _operator, Type const& _type)
{
if (_operator == Token::EQ || _operator == Token::NE)
{
m_context << eth::Instruction::EQ;
if (_operator == Token::NE)
m_context << eth::Instruction::ISZERO;
}
else
{
IntegerType const& type = dynamic_cast<IntegerType const&>(_type);
bool const isSigned = type.isSigned();
switch (_operator)
{
case Token::GTE:
m_context << (isSigned ? eth::Instruction::SLT : eth::Instruction::LT)
<< eth::Instruction::ISZERO;
break;
case Token::LTE:
m_context << (isSigned ? eth::Instruction::SGT : eth::Instruction::GT)
<< eth::Instruction::ISZERO;
break;
case Token::GT:
m_context << (isSigned ? eth::Instruction::SGT : eth::Instruction::GT);
break;
case Token::LT:
m_context << (isSigned ? eth::Instruction::SLT : eth::Instruction::LT);
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown comparison operator."));
}
}
}
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
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown binary operator."));
}
void ExpressionCompiler::appendArithmeticOperatorCode(Token::Value _operator, Type const& _type)
{
IntegerType const& type = dynamic_cast<IntegerType const&>(_type);
bool const isSigned = type.isSigned();
switch (_operator)
{
case Token::ADD:
m_context << eth::Instruction::ADD;
break;
case Token::SUB:
m_context << eth::Instruction::SUB;
break;
case Token::MUL:
m_context << eth::Instruction::MUL;
break;
case Token::DIV:
m_context << (isSigned ? eth::Instruction::SDIV : eth::Instruction::DIV);
break;
case Token::MOD:
m_context << (isSigned ? eth::Instruction::SMOD : eth::Instruction::MOD);
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown arithmetic operator."));
}
}
void ExpressionCompiler::appendBitOperatorCode(Token::Value _operator)
{
switch (_operator)
{
case Token::BIT_OR:
m_context << eth::Instruction::OR;
break;
case Token::BIT_AND:
m_context << eth::Instruction::AND;
break;
case Token::BIT_XOR:
m_context << eth::Instruction::XOR;
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown bit operator."));
}
}
void ExpressionCompiler::appendShiftOperatorCode(Token::Value _operator)
{
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Shift operators not yet implemented."));
switch (_operator)
{
case Token::SHL:
break;
case Token::SAR:
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown shift operator."));
}
}
void ExpressionCompiler::appendTypeConversion(Type const& _typeOnStack, Type const& _targetType, bool _cleanupNeeded)
{
// For a type extension, 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 && !_cleanupNeeded)
return;
if (_typeOnStack.getCategory() == Type::Category::INTEGER)
appendHighBitsCleanup(dynamic_cast<IntegerType const&>(_typeOnStack));
else if (_typeOnStack != _targetType)
// All other types should not be convertible to non-equal types.
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Invalid type conversion requested."));
}
void ExpressionCompiler::appendHighBitsCleanup(IntegerType const& _typeOnStack)
{
if (_typeOnStack.getNumBits() == 256)
return;
else if (_typeOnStack.isSigned())
m_context << u256(_typeOnStack.getNumBits() / 8 - 1) << eth::Instruction::SIGNEXTEND;
else
m_context << ((u256(1) << _typeOnStack.getNumBits()) - 1) << eth::Instruction::AND;
}
void ExpressionCompiler::LValue::retrieveValue(Expression const& _expression, bool _remove) const
{
switch (m_type)
{
case CODE:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Tried to retrieve value of a function."));
break;
case STACK:
{
unsigned stackPos = m_context->baseToCurrentStackOffset(unsigned(m_baseStackOffset));
if (stackPos >= 15) //@todo correct this by fetching earlier or moving to memory
BOOST_THROW_EXCEPTION(CompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Stack too deep."));
*m_context << eth::dupInstruction(stackPos + 1);
break;
}
case STORAGE:
if (!_remove)
*m_context << eth::Instruction::DUP1;
*m_context << eth::Instruction::SLOAD;
break;
case MEMORY:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Location type not yet implemented."));
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Unsupported location type."));
break;
}
}
void ExpressionCompiler::LValue::storeValue(Expression const& _expression, bool _move) const
{
switch (m_type)
{
case STACK:
{
unsigned stackPos = m_context->baseToCurrentStackOffset(unsigned(m_baseStackOffset));
if (stackPos > 16)
BOOST_THROW_EXCEPTION(CompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Stack too deep."));
else if (stackPos > 0)
*m_context << eth::swapInstruction(stackPos) << eth::Instruction::POP;
if (!_move)
retrieveValue(_expression);
break;
}
case LValue::STORAGE:
if (!_move)
*m_context << eth::Instruction::DUP2 << eth::Instruction::SWAP1;
*m_context << eth::Instruction::SSTORE;
break;
case LValue::CODE:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Location type does not support assignment."));
break;
case LValue::MEMORY:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Location type not yet implemented."));
break;
default:
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Unsupported location type."));
break;
}
}
void ExpressionCompiler::LValue::retrieveValueIfLValueNotRequested(const Expression& _expression)
{
if (!_expression.lvalueRequested())
{
retrieveValue(_expression, true);
reset();
}
}
void ExpressionCompiler::LValue::fromDeclaration( Expression const& _expression, Declaration const& _declaration)
{
if (m_context->isLocalVariable(&_declaration))
{
m_type = STACK;
m_baseStackOffset = m_context->getBaseStackOffsetOfVariable(_declaration);
}
else if (m_context->isStateVariable(&_declaration))
{
m_type = STORAGE;
*m_context << m_context->getStorageLocationOfVariable(_declaration);
}
else if (m_context->isFunctionDefinition(&_declaration))
{
m_type = CODE;
*m_context << m_context->getFunctionEntryLabel(dynamic_cast<FunctionDefinition const&>(_declaration)).pushTag();
}
else
BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_sourceLocation(_expression.getLocation())
<< errinfo_comment("Identifier type not supported or identifier not found."));
}
}
}
