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/*
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>
* @author Gav Wood <g@ethdev.com>
* @date 2014
* Solidity AST to EVM bytecode compiler for expressions.
*/
#include <functional>
#include <memory>
#include <boost/noncopyable.hpp>
#include <libdevcore/Common.h>
#include <libevmcore/SourceLocation.h>
#include <libsolidity/Utils.h>
#include <libsolidity/ASTVisitor.h>
#include <libsolidity/LValue.h>
namespace dev {
namespace eth
{
class AssemblyItem; // forward
}
namespace solidity {
// forward declarations
class CompilerContext;
class Type;
class IntegerType;
class ArrayType;
class StaticStringType;
/**
* Compiler for expressions, i.e. converts an AST tree whose root is an Expression into a stream
* of EVM instructions. It needs a compiler context that is the same for the whole compilation
* unit.
*/
class ExpressionCompiler: private ASTConstVisitor
{
public:
/// Appends code for a State Variable accessor function
static void appendStateVariableAccessor(CompilerContext& _context, VariableDeclaration const& _varDecl, bool _optimize = false);
explicit ExpressionCompiler(CompilerContext& _compilerContext, bool _optimize = false):
m_optimize(_optimize), m_context(_compilerContext) {}
/// Compile the given @a _expression and leave its value on the stack.
void compile(Expression const& _expression);
/// Appends code to set a state variable to its initial value/expression.
void appendStateVariableInitialization(VariableDeclaration const& _varDecl);
/// Appends code for a State Variable accessor function
void appendStateVariableAccessor(VariableDeclaration const& _varDecl);
/// Appends an implicit or explicit type conversion. For now this comprises only erasing
/// higher-order bits (@see appendHighBitCleanup) when widening integer.
/// If @a _cleanupNeeded, high order bits cleanup is also done if no type conversion would be
/// necessary.
void appendTypeConversion(Type const& _typeOnStack, Type const& _targetType, bool _cleanupNeeded = false);
private:
virtual bool visit(Assignment const& _assignment) override;
virtual bool visit(UnaryOperation const& _unaryOperation) override;
virtual bool visit(BinaryOperation const& _binaryOperation) override;
virtual bool visit(FunctionCall const& _functionCall) override;
virtual bool visit(NewExpression const& _newExpression) override;
virtual void endVisit(MemberAccess const& _memberAccess) override;
virtual bool visit(IndexAccess const& _indexAccess) override;
virtual void endVisit(Identifier const& _identifier) override;
virtual void endVisit(Literal const& _literal) override;
///@{
///@name Append code for various operator types
void appendAndOrOperatorCode(BinaryOperation const& _binaryOperation);
void appendCompareOperatorCode(Token::Value _operator, Type const& _type);
void appendOrdinaryBinaryOperatorCode(Token::Value _operator, Type const& _type);
void appendArithmeticOperatorCode(Token::Value _operator, Type const& _type);
void appendBitOperatorCode(Token::Value _operator);
void appendShiftOperatorCode(Token::Value _operator);
/// @}
//// Appends code that cleans higher-order bits for integer types.
void appendHighBitsCleanup(IntegerType const& _typeOnStack);
/// Appends code to call a function of the given type with the given arguments.
void appendExternalFunctionCall(FunctionType const& _functionType, std::vector<ASTPointer<Expression const>> const& _arguments,
bool bare = false);
/// Appends code that evaluates the given arguments and moves the result to memory. The memory offset is
/// expected to be on the stack and is updated by this call.
void appendArgumentsCopyToMemory(std::vector<ASTPointer<Expression const>> const& _arguments,
TypePointers const& _types = {},
bool _padToWordBoundaries = true,
bool _padExceptionIfFourBytes = false);
/// Appends code that moves a stack element of the given type to memory. The memory offset is
/// expected below the stack element and is updated by this call.
void appendTypeMoveToMemory(Type const& _type, bool _padToWordBoundaries = true);
/// Appends code that evaluates a single expression and moves the result to memory. The memory offset is
/// expected to be on the stack and is updated by this call.
void appendExpressionCopyToMemory(Type const& _expectedType, Expression const& _expression);
/// Sets the current LValue to a new one (of the appropriate type) from the given declaration.
/// Also retrieves the value if it was not requested by @a _expression.
void setLValueFromDeclaration(Declaration const& _declaration, Expression const& _expression);
/// Sets the current LValue to a StorageItem holding the type of @a _expression. The reference is assumed
/// to be on the stack.
/// Also retrieves the value if it was not requested by @a _expression.
void setLValueToStorageItem(Expression const& _expression);
/// Sets the current LValue to a new LValue constructed from the arguments.
/// Also retrieves the value if it was not requested by @a _expression.
template <class _LValueType, class... _Arguments>
void setLValue(Expression const& _expression, _Arguments const&... _arguments);
bool m_optimize;
CompilerContext& m_context;
std::unique_ptr<LValue> m_currentLValue;
};
template <class _LValueType, class... _Arguments>
void ExpressionCompiler::setLValue(Expression const& _expression, _Arguments const&... _arguments)
{
solAssert(!m_currentLValue, "Current LValue not reset before trying to set new one.");
std::unique_ptr<_LValueType> lvalue(new _LValueType(m_context, _arguments...));
if (_expression.lvalueRequested())
m_currentLValue = move(lvalue);
else
lvalue->retrieveValue(_expression.getLocation(), true);
}
}
}
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