path: root/Compiler.cpp

/*
    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 compiler.
 */

#include <algorithm>
#include <libevmcore/Instruction.h>
#include <libevmcore/Assembly.h>
#include <libsolidity/AST.h>
#include <libsolidity/Compiler.h>
#include <libsolidity/ExpressionCompiler.h>
#include <libsolidity/CompilerUtils.h>
#include <libsolidity/CallGraph.h>

using namespace std;

namespace dev {
namespace solidity {

void Compiler::compileContract(ContractDefinition const& _contract, vector<MagicVariableDeclaration const*> const& _magicGlobals,
                               map<ContractDefinition const*, bytes const*> const& _contracts)
{
    m_context = CompilerContext(); // clear it just in case
    initializeContext(_contract, _magicGlobals, _contracts);

    for (ASTPointer<FunctionDefinition> const& function: _contract.getDefinedFunctions())
        if (function->getName() != _contract.getName()) // don't add the constructor here
            m_context.addFunction(*function);

    appendFunctionSelector(_contract);
    for (ASTPointer<FunctionDefinition> const& function: _contract.getDefinedFunctions())
        if (function->getName() != _contract.getName()) // don't add the constructor here
            function->accept(*this);

    // Swap the runtime context with the creation-time context
    CompilerContext runtimeContext;
    swap(m_context, runtimeContext);
    initializeContext(_contract, _magicGlobals, _contracts);
    packIntoContractCreator(_contract, runtimeContext);
}

void Compiler::initializeContext(ContractDefinition const& _contract, vector<MagicVariableDeclaration const*> const& _magicGlobals,
                                 map<ContractDefinition const*, bytes const*> const& _contracts)
{
    m_context.setCompiledContracts(_contracts);
    for (MagicVariableDeclaration const* variable: _magicGlobals)
        m_context.addMagicGlobal(*variable);
    registerStateVariables(_contract);
}

void Compiler::packIntoContractCreator(ContractDefinition const& _contract, CompilerContext const& _runtimeContext)
{
    set<FunctionDefinition const*> neededFunctions;
    FunctionDefinition const* constructor = _contract.getConstructor();
    if (constructor)
        neededFunctions = getFunctionsNeededByConstructor(*constructor);

    for (FunctionDefinition const* fun: neededFunctions)
        m_context.addFunction(*fun);

    if (constructor)
        appendConstructorCall(*constructor);

    eth::AssemblyItem sub = m_context.addSubroutine(_runtimeContext.getAssembly());
    // stack contains sub size
    m_context << eth::Instruction::DUP1 << sub << u256(0) << eth::Instruction::CODECOPY;
    m_context << u256(0) << eth::Instruction::RETURN;

    // note that we have to explicitly include all used functions because of absolute jump
    // labels
    for (FunctionDefinition const* fun: neededFunctions)
        fun->accept(*this);
}

void Compiler::appendConstructorCall(FunctionDefinition const& _constructor)
{
    eth::AssemblyItem returnTag = m_context.pushNewTag();
    // copy constructor arguments from code to memory and then to stack, they are supplied after the actual program
    unsigned argumentSize = 0;
    for (ASTPointer<VariableDeclaration> const& var: _constructor.getParameters())
        argumentSize += var->getType()->getCalldataEncodedSize();
    if (argumentSize > 0)
    {
        m_context << u256(argumentSize);
        m_context.appendProgramSize();
        m_context << u256(1); // copy it to byte one as expected for ABI calls
        m_context << eth::Instruction::CODECOPY;
        appendCalldataUnpacker(_constructor, true);
    }
    m_context.appendJumpTo(m_context.getFunctionEntryLabel(_constructor));
    m_context << returnTag;
}

set<FunctionDefinition const*> Compiler::getFunctionsNeededByConstructor(FunctionDefinition const& _constructor)
{
    CallGraph callgraph;
    callgraph.addFunction(_constructor);
    callgraph.computeCallGraph();
    return callgraph.getCalls();
}

void Compiler::appendFunctionSelector(ContractDefinition const& _contract)
{
    vector<FunctionDefinition const*> interfaceFunctions = _contract.getInterfaceFunctions();
    vector<eth::AssemblyItem> callDataUnpackerEntryPoints;

    if (interfaceFunctions.size() > 255)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("More than 255 public functions for contract."));

    // retrieve the first byte of the call data, which determines the called function
    // @todo This code had a jump table in a previous version which was more efficient but also
    // error prone (due to the optimizer and variable length tag addresses)
    m_context << u256(1) << u256(0) // some constants
              << eth::dupInstruction(1) << eth::Instruction::CALLDATALOAD
              << eth::dupInstruction(2) << eth::Instruction::BYTE
              << eth::dupInstruction(2);

    // stack here: 1 0 <funid> 0, stack top will be counted up until it matches funid
    for (unsigned funid = 0; funid < interfaceFunctions.size(); ++funid)
    {
        callDataUnpackerEntryPoints.push_back(m_context.newTag());
        m_context << eth::dupInstruction(2) << eth::dupInstruction(2) << eth::Instruction::EQ;
        m_context.appendConditionalJumpTo(callDataUnpackerEntryPoints.back());
        if (funid < interfaceFunctions.size() - 1)
            m_context << eth::dupInstruction(4) << eth::Instruction::ADD;
    }
    m_context << eth::Instruction::STOP; // function not found

    for (unsigned funid = 0; funid < interfaceFunctions.size(); ++funid)
    {
        FunctionDefinition const& function = *interfaceFunctions[funid];
        m_context << callDataUnpackerEntryPoints[funid];
        eth::AssemblyItem returnTag = m_context.pushNewTag();
        appendCalldataUnpacker(function);
        m_context.appendJumpTo(m_context.getFunctionEntryLabel(function));
        m_context << returnTag;
        appendReturnValuePacker(function);
    }
}

unsigned Compiler::appendCalldataUnpacker(FunctionDefinition const& _function, bool _fromMemory)
{
    // We do not check the calldata size, everything is zero-padded.
    unsigned dataOffset = 1;
    //@todo this can be done more efficiently, saving some CALLDATALOAD calls
    for (ASTPointer<VariableDeclaration> const& var: _function.getParameters())
    {
        unsigned const numBytes = var->getType()->getCalldataEncodedSize();
        if (numBytes > 32)
            BOOST_THROW_EXCEPTION(CompilerError()
                                  << errinfo_sourceLocation(var->getLocation())
                                  << errinfo_comment("Type " + var->getType()->toString() + " not yet supported."));
        bool leftAligned = var->getType()->getCategory() == Type::Category::STRING;
        CompilerUtils(m_context).loadFromMemory(dataOffset, numBytes, leftAligned, !_fromMemory);
        dataOffset += numBytes;
    }
    return dataOffset;
}

void Compiler::appendReturnValuePacker(FunctionDefinition const& _function)
{
    //@todo this can be also done more efficiently
    unsigned dataOffset = 0;
    vector<ASTPointer<VariableDeclaration>> const& parameters = _function.getReturnParameters();
    unsigned stackDepth = CompilerUtils(m_context).getSizeOnStack(parameters);
    for (unsigned i = 0; i < parameters.size(); ++i)
    {
        Type const& paramType = *parameters[i]->getType();
        unsigned numBytes = paramType.getCalldataEncodedSize();
        if (numBytes > 32)
            BOOST_THROW_EXCEPTION(CompilerError()
                                  << errinfo_sourceLocation(parameters[i]->getLocation())
                                  << errinfo_comment("Type " + paramType.toString() + " not yet supported."));
        CompilerUtils(m_context).copyToStackTop(stackDepth, paramType);
        bool const leftAligned = paramType.getCategory() == Type::Category::STRING;
        CompilerUtils(m_context).storeInMemory(dataOffset, numBytes, leftAligned);
        stackDepth -= paramType.getSizeOnStack();
        dataOffset += numBytes;
    }
    // note that the stack is not cleaned up here
    m_context << u256(dataOffset) << u256(0) << eth::Instruction::RETURN;
}

void Compiler::registerStateVariables(ContractDefinition const& _contract)
{
    //@todo sort them?
    for (ASTPointer<VariableDeclaration> const& variable: _contract.getStateVariables())
        m_context.addStateVariable(*variable);
}

bool Compiler::visit(FunctionDefinition const& _function)
{
    //@todo to simplify this, the calling convention could by changed such that
    // caller puts: [retarg0] ... [retargm] [return address] [arg0] ... [argn]
    // although note that this reduces the size of the visible stack

    m_context.startNewFunction();
    m_returnTag = m_context.newTag();
    m_breakTags.clear();
    m_continueTags.clear();

    m_context << m_context.getFunctionEntryLabel(_function);

    // stack upon entry: [return address] [arg0] [arg1] ... [argn]
    // reserve additional slots: [retarg0] ... [retargm] [localvar0] ... [localvarp]

    for (ASTPointer<VariableDeclaration const> const& variable: _function.getParameters())
        m_context.addVariable(*variable);
    for (ASTPointer<VariableDeclaration const> const& variable: _function.getReturnParameters())
        m_context.addAndInitializeVariable(*variable);
    for (VariableDeclaration const* localVariable: _function.getLocalVariables())
        m_context.addAndInitializeVariable(*localVariable);

    _function.getBody().accept(*this);

    m_context << m_returnTag;

    // Now we need to re-shuffle the stack. For this we keep a record of the stack layout
    // that shows the target positions of the elements, where "-1" denotes that this element needs
    // to be removed from the stack.
    // Note that the fact that the return arguments are of increasing index is vital for this
    // algorithm to work.

    unsigned const argumentsSize = CompilerUtils::getSizeOnStack(_function.getParameters());
    unsigned const returnValuesSize = CompilerUtils::getSizeOnStack(_function.getReturnParameters());
    unsigned const localVariablesSize = CompilerUtils::getSizeOnStack(_function.getLocalVariables());

    vector<int> stackLayout;
    stackLayout.push_back(returnValuesSize); // target of return address
    stackLayout += vector<int>(argumentsSize, -1); // discard all arguments
    for (unsigned i = 0; i < returnValuesSize; ++i)
        stackLayout.push_back(i);
    stackLayout += vector<int>(localVariablesSize, -1);

    while (stackLayout.back() != int(stackLayout.size() - 1))
        if (stackLayout.back() < 0)
        {
            m_context << eth::Instruction::POP;
            stackLayout.pop_back();
        }
        else
        {
            m_context << eth::swapInstruction(stackLayout.size() - stackLayout.back() - 1);
            swap(stackLayout[stackLayout.back()], stackLayout.back());
        }
    //@todo assert that everything is in place now

    m_context << eth::Instruction::JUMP;

    return false;
}

bool Compiler::visit(IfStatement const& _ifStatement)
{
    compileExpression(_ifStatement.getCondition());
    eth::AssemblyItem trueTag = m_context.appendConditionalJump();
    if (_ifStatement.getFalseStatement())
        _ifStatement.getFalseStatement()->accept(*this);
    eth::AssemblyItem endTag = m_context.appendJumpToNew();
    m_context << trueTag;
    _ifStatement.getTrueStatement().accept(*this);
    m_context << endTag;
    return false;
}

bool Compiler::visit(WhileStatement const& _whileStatement)
{
    eth::AssemblyItem loopStart = m_context.newTag();
    eth::AssemblyItem loopEnd = m_context.newTag();
    m_continueTags.push_back(loopStart);
    m_breakTags.push_back(loopEnd);

    m_context << loopStart;
    compileExpression(_whileStatement.getCondition());
    m_context << eth::Instruction::ISZERO;
    m_context.appendConditionalJumpTo(loopEnd);

    _whileStatement.getBody().accept(*this);

    m_context.appendJumpTo(loopStart);
    m_context << loopEnd;

    m_continueTags.pop_back();
    m_breakTags.pop_back();
    return false;
}

bool Compiler::visit(ForStatement const& _forStatement)
{
    eth::AssemblyItem loopStart = m_context.newTag();
    eth::AssemblyItem loopEnd = m_context.newTag();
    m_continueTags.push_back(loopStart);
    m_breakTags.push_back(loopEnd);

    if (_forStatement.getInitializationExpression())
        _forStatement.getInitializationExpression()->accept(*this);

    m_context << loopStart;

    // if there is no terminating condition in for, default is to always be true
    if (_forStatement.getCondition())
    {
        compileExpression(*_forStatement.getCondition());
        m_context << eth::Instruction::ISZERO;
        m_context.appendConditionalJumpTo(loopEnd);
    }

    _forStatement.getBody().accept(*this);

    // for's loop expression if existing
    if (_forStatement.getLoopExpression())
        _forStatement.getLoopExpression()->accept(*this);

    m_context.appendJumpTo(loopStart);
    m_context << loopEnd;

    m_continueTags.pop_back();
    m_breakTags.pop_back();
    return false;
}

bool Compiler::visit(Continue const&)
{
    if (!m_continueTags.empty())
        m_context.appendJumpTo(m_continueTags.back());
    return false;
}

bool Compiler::visit(Break const&)
{
    if (!m_breakTags.empty())
        m_context.appendJumpTo(m_breakTags.back());
    return false;
}

bool Compiler::visit(Return const& _return)
{
    //@todo modifications are needed to make this work with functions returning multiple values
    if (Expression const* expression = _return.getExpression())
    {
        compileExpression(*expression);
        VariableDeclaration const& firstVariable = *_return.getFunctionReturnParameters().getParameters().front();
        ExpressionCompiler::appendTypeConversion(m_context, *expression->getType(), *firstVariable.getType());

        CompilerUtils(m_context).moveToStackVariable(firstVariable);
    }
    m_context.appendJumpTo(m_returnTag);
    return false;
}

bool Compiler::visit(VariableDefinition const& _variableDefinition)
{
    if (Expression const* expression = _variableDefinition.getExpression())
    {
        compileExpression(*expression);
        ExpressionCompiler::appendTypeConversion(m_context,
                                                 *expression->getType(),
                                                 *_variableDefinition.getDeclaration().getType());
        CompilerUtils(m_context).moveToStackVariable(_variableDefinition.getDeclaration());
    }
    return false;
}

bool Compiler::visit(ExpressionStatement const& _expressionStatement)
{
    Expression const& expression = _expressionStatement.getExpression();
    compileExpression(expression);
    CompilerUtils(m_context).popStackElement(*expression.getType());
    return false;
}

void Compiler::compileExpression(Expression const& _expression)
{
    ExpressionCompiler::compileExpression(m_context, _expression, m_optimize);
}

}
}