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 <boost/range/adaptor/reversed.hpp>
#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,
                               map<ContractDefinition const*, bytes const*> const& _contracts)
{
    m_context = CompilerContext(); // clear it just in case
    initializeContext(_contract, _contracts);

    for (ContractDefinition const* contract: _contract.getLinearizedBaseContracts())
    {
        for (ASTPointer<FunctionDefinition> const& function: contract->getDefinedFunctions())
            if (!function->isConstructor())
                m_context.addFunction(*function);
        for (ASTPointer<ModifierDefinition> const& modifier: contract->getFunctionModifiers())
            m_context.addModifier(*modifier);
    }

    appendFunctionSelector(_contract);
    for (ContractDefinition const* contract: _contract.getLinearizedBaseContracts())
        for (ASTPointer<FunctionDefinition> const& function: contract->getDefinedFunctions())
            if (!function->isConstructor())
                function->accept(*this);

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

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

void Compiler::packIntoContractCreator(ContractDefinition const& _contract, CompilerContext const& _runtimeContext)
{
    std::vector<ContractDefinition const*> const& bases = _contract.getLinearizedBaseContracts();

    // Make all modifiers known to the context.
    for (ContractDefinition const* contract: bases)
        for (ASTPointer<ModifierDefinition> const& modifier: contract->getFunctionModifiers())
            m_context.addModifier(*modifier);

    // arguments for base constructors, filled in derived-to-base order
    map<ContractDefinition const*, vector<ASTPointer<Expression>> const*> baseArguments;
    set<FunctionDefinition const*> neededFunctions;
    set<ASTNode const*> nodesUsedInConstructors;

    // Determine the arguments that are used for the base constructors and also which functions
    // are needed at compile time.
    for (ContractDefinition const* contract: bases)
    {
        if (FunctionDefinition const* constructor = contract->getConstructor())
            nodesUsedInConstructors.insert(constructor);
        for (ASTPointer<InheritanceSpecifier> const& base: contract->getBaseContracts())
        {
            ContractDefinition const* baseContract = dynamic_cast<ContractDefinition const*>(
                                                    base->getName()->getReferencedDeclaration());
            solAssert(baseContract, "");
            if (baseArguments.count(baseContract) == 0)
            {
                baseArguments[baseContract] = &base->getArguments();
                for (ASTPointer<Expression> const& arg: base->getArguments())
                    nodesUsedInConstructors.insert(arg.get());
            }
        }
    }

    auto functionOverrideResolver = [&](string const& _name) -> FunctionDefinition const*
    {
        for (ContractDefinition const* contract: bases)
            for (ASTPointer<FunctionDefinition> const& function: contract->getDefinedFunctions())
                if (!function->isConstructor() && function->getName() == _name)
                    return function.get();
        return nullptr;
    };
    auto modifierOverrideResolver = [&](string const& _name) -> ModifierDefinition const*
    {
        return &m_context.getFunctionModifier(_name);
    };

    neededFunctions = getFunctionsCalled(nodesUsedInConstructors, functionOverrideResolver,
                                         modifierOverrideResolver);

    // First add all overrides (or the functions themselves if there is no override)
    for (FunctionDefinition const* fun: neededFunctions)
    {
        FunctionDefinition const* override = nullptr;
        if (!fun->isConstructor())
            override = functionOverrideResolver(fun->getName());
        if (!!override && neededFunctions.count(override))
            m_context.addFunction(*override);
    }
    // now add the rest
    for (FunctionDefinition const* fun: neededFunctions)
        if (fun->isConstructor() || functionOverrideResolver(fun->getName()) != fun)
            m_context.addFunction(*fun);

    // Call constructors in base-to-derived order.
    // The Constructor for the most derived contract is called later.
    for (unsigned i = 1; i < bases.size(); i++)
    {
        ContractDefinition const* base = bases[bases.size() - i];
        solAssert(base, "");
        FunctionDefinition const* baseConstructor = base->getConstructor();
        if (!baseConstructor)
            continue;
        solAssert(baseArguments[base], "");
        appendBaseConstructorCall(*baseConstructor, *baseArguments[base]);
    }
    if (_contract.getConstructor())
        appendConstructorCall(*_contract.getConstructor());

    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::appendBaseConstructorCall(FunctionDefinition const& _constructor,
                                         vector<ASTPointer<Expression>> const& _arguments)
{
    FunctionType constructorType(_constructor);
    eth::AssemblyItem returnLabel = m_context.pushNewTag();
    for (unsigned i = 0; i < _arguments.size(); ++i)
        compileExpression(*_arguments[i], constructorType.getParameterTypes()[i]);
    m_context.appendJumpTo(m_context.getFunctionEntryLabel(_constructor));
    m_context << returnLabel;
}

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 += CompilerUtils::getPaddedSize(var->getType()->getCalldataEncodedSize());

    if (argumentSize > 0)
    {
        m_context << u256(argumentSize);
        m_context.appendProgramSize();
        m_context << u256(CompilerUtils::dataStartOffset); // copy it to byte four as expected for ABI calls
        m_context << eth::Instruction::CODECOPY;
        appendCalldataUnpacker(FunctionType(_constructor).getParameterTypes(), true);
    }
    m_context.appendJumpTo(m_context.getFunctionEntryLabel(_constructor));
    m_context << returnTag;
}

set<FunctionDefinition const*> Compiler::getFunctionsCalled(set<ASTNode const*> const& _nodes,
                        function<FunctionDefinition const*(string const&)> const& _resolveFunctionOverrides,
                        function<ModifierDefinition const*(string const&)> const& _resolveModifierOverrides)
{
    CallGraph callgraph(_resolveFunctionOverrides, _resolveModifierOverrides);
    for (ASTNode const* node: _nodes)
        callgraph.addNode(*node);
    return callgraph.getCalls();
}

void Compiler::appendFunctionSelector(ContractDefinition const& _contract)
{
    map<FixedHash<4>, FunctionDescription> interfaceFunctions = _contract.getInterfaceFunctions();
    map<FixedHash<4>, const eth::AssemblyItem> callDataUnpackerEntryPoints;

    // retrieve the function signature hash from the calldata
    m_context << u256(1) << u256(0);
    CompilerUtils(m_context).loadFromMemory(0, 4, false, true);

    // stack now is: 1 0 <funhash>
    for (auto const& it: interfaceFunctions)
    {
        callDataUnpackerEntryPoints.insert(std::make_pair(it.first, m_context.newTag()));
        m_context << eth::dupInstruction(1) << u256(FixedHash<4>::Arith(it.first)) << eth::Instruction::EQ;
        m_context.appendConditionalJumpTo(callDataUnpackerEntryPoints.at(it.first));
    }
    m_context << eth::Instruction::STOP; // function not found

    for (auto const& it: interfaceFunctions)
    {
        FunctionType const* functionType = it.second.getFunctionType();
        m_context << callDataUnpackerEntryPoints.at(it.first);
        eth::AssemblyItem returnTag = m_context.pushNewTag();
        appendCalldataUnpacker(functionType->getParameterTypes());
        m_context.appendJumpTo(m_context.getFunctionEntryLabel(*it.second.getDeclaration()));
        m_context << returnTag;
        appendReturnValuePacker(functionType->getReturnParameterTypes());
    }
}

unsigned Compiler::appendCalldataUnpacker(TypePointers const& _typeParameters, bool _fromMemory)
{
    // We do not check the calldata size, everything is zero-padded.
    unsigned dataOffset = CompilerUtils::dataStartOffset; // the 4 bytes of the function hash signature
    //@todo this can be done more efficiently, saving some CALLDATALOAD calls
    for (TypePointer const& type: _typeParameters)
    {
        unsigned const c_numBytes = type->getCalldataEncodedSize();
        if (c_numBytes > 32)
            BOOST_THROW_EXCEPTION(CompilerError()
                                  << errinfo_comment("Type " + type->toString() + " not yet supported."));
        bool const c_leftAligned = type->getCategory() == Type::Category::STRING;
        bool const c_padToWords = true;
        dataOffset += CompilerUtils(m_context).loadFromMemory(dataOffset, c_numBytes, c_leftAligned,
                                                              !_fromMemory, c_padToWords);
    }
    return dataOffset;
}

void Compiler::appendReturnValuePacker(TypePointers const& _typeParameters)
{
    //@todo this can be also done more efficiently
    unsigned dataOffset = 0;
    unsigned stackDepth = 0;
    for (TypePointer const& type: _typeParameters)
        stackDepth += type->getSizeOnStack();

    for (TypePointer const& type: _typeParameters)
    {
        unsigned numBytes = type->getCalldataEncodedSize();
        if (numBytes > 32)
            BOOST_THROW_EXCEPTION(CompilerError()
                                  << errinfo_comment("Type " + type->toString() + " not yet supported."));
        CompilerUtils(m_context).copyToStackTop(stackDepth, *type);
        ExpressionCompiler::appendTypeConversion(m_context, *type, *type, true);
        bool const c_leftAligned = type->getCategory() == Type::Category::STRING;
        bool const c_padToWords = true;
        dataOffset += CompilerUtils(m_context).storeInMemory(dataOffset, numBytes, c_leftAligned, c_padToWords);
        stackDepth -= type->getSizeOnStack();
    }
    // note that the stack is not cleaned up here
    m_context << u256(dataOffset) << u256(0) << eth::Instruction::RETURN;
}

void Compiler::registerStateVariables(ContractDefinition const& _contract)
{
    for (ContractDefinition const* contract: boost::adaptors::reverse(_contract.getLinearizedBaseContracts()))
        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_stackCleanupForReturn = 0;
    m_currentFunction = &_function;
    m_modifierDepth = 0;

    m_context << m_context.getFunctionEntryLabel(_function);

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

    unsigned parametersSize = CompilerUtils::getSizeOnStack(_function.getParameters());
    m_context.adjustStackOffset(parametersSize);
    for (ASTPointer<VariableDeclaration const> const& variable: _function.getParameters())
    {
        m_context.addVariable(*variable, parametersSize);
        parametersSize -= variable->getType()->getSizeOnStack();
    }
    for (ASTPointer<VariableDeclaration const> const& variable: _function.getReturnParameters())
        m_context.addAndInitializeVariable(*variable);
    for (VariableDeclaration const* localVariable: _function.getLocalVariables())
        m_context.addAndInitializeVariable(*localVariable);

    appendModifierOrFunctionCode();

    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 c_argumentsSize = CompilerUtils::getSizeOnStack(_function.getParameters());
    unsigned const c_returnValuesSize = CompilerUtils::getSizeOnStack(_function.getReturnParameters());
    unsigned const c_localVariablesSize = CompilerUtils::getSizeOnStack(_function.getLocalVariables());

    vector<int> stackLayout;
    stackLayout.push_back(c_returnValuesSize); // target of return address
    stackLayout += vector<int>(c_argumentsSize, -1); // discard all arguments
    for (unsigned i = 0; i < c_returnValuesSize; ++i)
        stackLayout.push_back(i);
    stackLayout += vector<int>(c_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())
    {
        solAssert(_return.getFunctionReturnParameters(), "Invalid return parameters pointer.");
        VariableDeclaration const& firstVariable = *_return.getFunctionReturnParameters()->getParameters().front();
        compileExpression(*expression, firstVariable.getType());
        CompilerUtils(m_context).moveToStackVariable(firstVariable);
    }
    for (unsigned i = 0; i < m_stackCleanupForReturn; ++i)
        m_context << eth::Instruction::POP;
    m_context.appendJumpTo(m_returnTag);
    m_context.adjustStackOffset(m_stackCleanupForReturn);
    return false;
}

bool Compiler::visit(VariableDefinition const& _variableDefinition)
{
    if (Expression const* expression = _variableDefinition.getExpression())
    {
        compileExpression(*expression, _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;
}

bool Compiler::visit(PlaceholderStatement const&)
{
    ++m_modifierDepth;
    appendModifierOrFunctionCode();
    --m_modifierDepth;
    return true;
}

void Compiler::appendModifierOrFunctionCode()
{
    solAssert(m_currentFunction, "");
    if (m_modifierDepth >= m_currentFunction->getModifiers().size())
        m_currentFunction->getBody().accept(*this);
    else
    {
        ASTPointer<ModifierInvocation> const& modifierInvocation = m_currentFunction->getModifiers()[m_modifierDepth];

        ModifierDefinition const& modifier = m_context.getFunctionModifier(modifierInvocation->getName()->getName());
        solAssert(modifier.getParameters().size() == modifierInvocation->getArguments().size(), "");
        for (unsigned i = 0; i < modifier.getParameters().size(); ++i)
        {
            m_context.addVariable(*modifier.getParameters()[i]);
            compileExpression(*modifierInvocation->getArguments()[i],
                              modifier.getParameters()[i]->getType());
        }
        for (VariableDeclaration const* localVariable: modifier.getLocalVariables())
            m_context.addAndInitializeVariable(*localVariable);

        unsigned const c_stackSurplus = CompilerUtils::getSizeOnStack(modifier.getParameters()) +
                                        CompilerUtils::getSizeOnStack(modifier.getLocalVariables());
        m_stackCleanupForReturn += c_stackSurplus;

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

        for (unsigned i = 0; i < c_stackSurplus; ++i)
            m_context << eth::Instruction::POP;
        m_stackCleanupForReturn -= c_stackSurplus;
    }
}

void Compiler::compileExpression(Expression const& _expression, TypePointer const& _targetType)
{
    ExpressionCompiler::compileExpression(m_context, _expression, m_optimize);
    if (_targetType)
        ExpressionCompiler::appendTypeConversion(m_context, *_expression.getType(), *_targetType);
}

}
}