/*
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 <boost/noncopyable.hpp>
#include <libdevcore/Common.h>
#include <libsolidity/ASTVisitor.h>
namespace dev {
namespace eth
{
class AssemblyItem; // forward
}
namespace solidity {
// forward declarations
class CompilerContext;
class Type;
class IntegerType;
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:
/// Compile the given @a _expression into the @a _context.
static void compileExpression(CompilerContext& _context, Expression const& _expression, bool _optimize = false);
/// Appends code to remove dirty higher order bits in case of an implicit promotion to a wider type.
static void appendTypeConversion(CompilerContext& _context, Type const& _typeOnStack,
Type const& _targetType, bool _cleanupNeeded = false);
/// Appends code for a State Variable accessor function
static void appendStateVariableAccessor(CompilerContext& _context, VariableDeclaration const& _varDecl, bool _optimize = false);
private:
explicit ExpressionCompiler(CompilerContext& _compilerContext, bool _optimize = false):
m_optimize(_optimize), m_context(_compilerContext), m_currentLValue(m_context) {}
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 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);
//// 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 copies the given arguments to memory (with optional offset).
/// @returns the number of bytes copied to memory
unsigned appendArgumentCopyToMemory(TypePointers const& _types,
std::vector<ASTPointer<Expression const>> const& _arguments,
unsigned _memoryOffset = 0);
/// Appends code that evaluates a single expression and copies it to memory (with optional offset).
/// @returns the number of bytes copied to memory
unsigned appendExpressionCopyToMemory(Type const& _expectedType, Expression const& _expression,
unsigned _memoryOffset = 0);
/// Appends code for a State Variable accessor function
void appendStateVariableAccessor(VariableDeclaration const& _varDecl);
/**
* Helper class to store and retrieve lvalues to and from various locations.
* All types except STACK store a reference in a slot on the stack, STACK just
* stores the base stack offset of the variable in @a m_baseStackOffset.
*/
class LValue
{
public:
enum LValueType { NONE, STACK, MEMORY, STORAGE };
explicit LValue(CompilerContext& _compilerContext): m_context(&_compilerContext) { reset(); }
LValue(CompilerContext& _compilerContext, LValueType _type, Type const& _dataType, unsigned _baseStackOffset = 0);
/// Set type according to the declaration and retrieve the reference.
/// @a _expression is the current expression
void fromIdentifier(Identifier const& _identifier, Declaration const& _declaration);
/// Convenience function to set type for a state variable and retrieve the reference
void fromStateVariable(Declaration const& _varDecl, TypePointer const& _type);
void reset() { m_type = NONE; m_baseStackOffset = 0; m_size = 0; }
bool isValid() const { return m_type != NONE; }
bool isInOnStack() const { return m_type == STACK; }
bool isInMemory() const { return m_type == MEMORY; }
bool isInStorage() const { return m_type == STORAGE; }
/// @returns true if this lvalue reference type occupies a slot on the stack.
bool storesReferenceOnStack() const { return m_type == STORAGE || m_type == MEMORY; }
/// Copies the value of the current lvalue to the top of the stack and, if @a _remove is true,
/// also removes the reference from the stack (note that is does not reset the type to @a NONE).
/// @a _type is the type of the current expression and @ _location its location, used for error reporting.
/// @a _location can be a nullptr for expressions that don't have an actual ASTNode equivalent
void retrieveValue(TypePointer const& _type, Location const& _location, bool _remove = false) const;
/// Stores a value (from the stack directly beneath the reference, which is assumed to
/// be on the top of the stack, if any) in the lvalue and removes the reference.
/// Also removes the stored value from the stack if @a _move is
/// true. @a _expression is the current expression, used for error reporting.
void storeValue(Expression const& _expression, bool _move = false) const;
/// Stores zero in the lvalue.
/// @a _expression is the current expression, used for error reporting.
void setToZero(Expression const& _expression) const;
/// Convenience function to convert the stored reference to a value and reset type to NONE if
/// the reference was not requested by @a _expression.
void retrieveValueIfLValueNotRequested(Expression const& _expression);
private:
/// Convenience function to retrieve Value from Storage. Specific version of @ref retrieveValue
void retrieveValueFromStorage(TypePointer const& _type, bool _remove = false) const;
CompilerContext* m_context;
LValueType m_type = NONE;
/// If m_type is STACK, this is base stack offset (@see
/// CompilerContext::getBaseStackOffsetOfVariable) of a local variable.
unsigned m_baseStackOffset = 0;
/// Size of the value of this lvalue on the stack or the storage.
unsigned m_size = 0;
};
bool m_optimize;
CompilerContext& m_context;
LValue m_currentLValue;
};
}
}
