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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>
* @date 2014
* Solidity AST to EVM bytecode compiler.
*/
#include <libevmface/Instruction.h>
#include <libsolidity/ASTVisitor.h>
#include <libsolidity/Types.h>
#include <libsolidity/Token.h>
namespace dev {
namespace solidity {
/**
* A single item of compiled code that can be assembled to a single byte value in the final
* bytecode. Its main purpose is to inject jump labels and label references into the opcode stream,
* which can be resolved in the final step.
*/
class AssemblyItem
{
public:
enum class Type
{
CODE, //< m_data is opcode, m_label is empty.
DATA, //< m_data is actual data, m_label is empty
LABEL, //< m_data is JUMPDEST opcode, m_label is id of label
LABELREF //< m_data is empty, m_label is id of label
};
explicit AssemblyItem(eth::Instruction _instruction) : m_type(Type::CODE), m_data(byte(_instruction)) {}
explicit AssemblyItem(byte _data): m_type(Type::DATA), m_data(_data) {}
/// Factory functions
static AssemblyItem labelRef(uint32_t _label) { return AssemblyItem(Type::LABELREF, 0, _label); }
static AssemblyItem label(uint32_t _label) { return AssemblyItem(Type::LABEL, byte(eth::Instruction::JUMPDEST), _label); }
Type getType() const { return m_type; }
byte getData() const { return m_data; }
uint32_t getLabel() const { return m_label; }
private:
AssemblyItem(Type _type, byte _data, uint32_t _label): m_type(_type), m_data(_data), m_label(_label) {}
Type m_type;
byte m_data; //< data to be written to the bytecode stream (or filled by a label if this is a LABELREF)
uint32_t m_label; //< the id of a label either referenced or defined by this item
};
using AssemblyItems = std::vector<AssemblyItem>;
/**
* Context to be shared by all units that compile the same contract. Its current usage only
* concerns dispensing unique jump label IDs and storing their actual positions in the bytecode
* stream.
*/
class CompilerContext
{
public:
CompilerContext(): m_nextLabel(0) {}
uint32_t dispenseNewLabel() { return m_nextLabel++; }
void setLabelPosition(uint32_t _label, uint32_t _position);
uint32_t getLabelPosition(uint32_t _label) const;
private:
uint32_t m_nextLabel;
std::map<uint32_t, uint32_t> m_labelPositions;
};
/**
* 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: public ASTVisitor
{
public:
ExpressionCompiler(CompilerContext& _compilerContext): m_context(_compilerContext) {}
/// Compile the given expression and (re-)populate the assembly item list.
void compile(Expression& _expression);
AssemblyItems const& getAssemblyItems() const { return m_assemblyItems; }
bytes getAssembledBytecode() const;
/// Compile the given expression and return the assembly items right away.
static AssemblyItems compileExpression(CompilerContext& _context, Expression& _expression);
private:
virtual void endVisit(Assignment& _assignment) override;
virtual void endVisit(UnaryOperation& _unaryOperation) override;
virtual bool visit(BinaryOperation& _binaryOperation) override;
virtual void endVisit(FunctionCall& _functionCall) override;
virtual void endVisit(MemberAccess& _memberAccess) override;
virtual void endVisit(IndexAccess& _indexAccess) override;
virtual void endVisit(Identifier& _identifier) override;
virtual void endVisit(Literal& _literal) override;
/// Appends code to remove dirty higher order bits in case of an implicit promotion to a wider type.
void cleanHigherOrderBitsIfNeeded(Type const& _typeOnStack, Type const& _targetType);
///@{
///@name Append code for various operator types
void appendAndOrOperatorCode(BinaryOperation& _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 a JUMPI instruction to a new label and returns the label
uint32_t appendConditionalJump();
/// Append elements to the current instruction list.
void append(eth::Instruction const& _instruction) { m_assemblyItems.push_back(AssemblyItem(_instruction)); }
void append(byte _value) { m_assemblyItems.push_back(AssemblyItem(_value)); }
void append(bytes const& _data);
void appendLabelref(byte _label) { m_assemblyItems.push_back(AssemblyItem::labelRef(_label)); }
void appendLabel(byte _label) { m_assemblyItems.push_back(AssemblyItem::label(_label)); }
AssemblyItems m_assemblyItems;
CompilerContext& m_context;
};
}
}
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