path: root/libsolidity/inlineasm/AsmAnalysis.cpp

/*
    This file is part of solidity.

    solidity 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.

    solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * Analyzer part of inline assembly.
 */

#include <libsolidity/inlineasm/AsmAnalysis.h>

#include <libsolidity/inlineasm/AsmData.h>
#include <libsolidity/inlineasm/AsmScopeFiller.h>
#include <libsolidity/inlineasm/AsmScope.h>
#include <libsolidity/inlineasm/AsmAnalysisInfo.h>

#include <libsolidity/interface/Exceptions.h>
#include <libsolidity/interface/Utils.h>

#include <boost/range/adaptor/reversed.hpp>

#include <memory>
#include <functional>

using namespace std;
using namespace dev;
using namespace dev::solidity;
using namespace dev::solidity::assembly;

AsmAnalyzer::AsmAnalyzer(
    AsmAnalysisInfo& _analysisInfo,
    ErrorList& _errors,
    ExternalIdentifierAccess::Resolver const& _resolver
):
    m_resolver(_resolver), m_info(_analysisInfo), m_errors(_errors)
{
}

bool AsmAnalyzer::analyze(Block const& _block)
{
    if (!(ScopeFiller(m_info.scopes, m_errors))(_block))
        return false;

    return (*this)(_block);
}

bool AsmAnalyzer::operator()(Label const& _label)
{
    m_info.stackHeightInfo[&_label] = m_stackHeight;
    return true;
}

bool AsmAnalyzer::operator()(assembly::Instruction const& _instruction)
{
    auto const& info = instructionInfo(_instruction.instruction);
    m_stackHeight += info.ret - info.args;
    m_info.stackHeightInfo[&_instruction] = m_stackHeight;
    return true;
}

bool AsmAnalyzer::operator()(assembly::Literal const& _literal)
{
    ++m_stackHeight;
    if (_literal.kind == assembly::LiteralKind::String && _literal.value.size() > 32)
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::TypeError,
            "String literal too long (" + boost::lexical_cast<std::string>(_literal.value.size()) + " > 32)",
            _literal.location
        ));
        return false;
    }
    m_info.stackHeightInfo[&_literal] = m_stackHeight;
    return true;
}

bool AsmAnalyzer::operator()(assembly::Identifier const& _identifier)
{
    size_t numErrorsBefore = m_errors.size();
    bool success = true;
    if (m_currentScope->lookup(_identifier.name, Scope::Visitor(
        [&](Scope::Variable const& _var)
        {
            if (!_var.active)
            {
                m_errors.push_back(make_shared<Error>(
                    Error::Type::DeclarationError,
                    "Variable " + _identifier.name + " used before it was declared.",
                    _identifier.location
                ));
                success = false;
            }
            ++m_stackHeight;
        },
        [&](Scope::Label const&)
        {
            ++m_stackHeight;
        },
        [&](Scope::Function const&)
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::TypeError,
                "Function " + _identifier.name + " used without being called.",
                _identifier.location
            ));
            success = false;
        }
    )))
    {
    }
    else
    {
        size_t stackSize(-1);
        if (m_resolver)
            stackSize = m_resolver(_identifier, IdentifierContext::RValue);
        if (stackSize == size_t(-1))
        {
            // Only add an error message if the callback did not do it.
            if (numErrorsBefore == m_errors.size())
                m_errors.push_back(make_shared<Error>(
                    Error::Type::DeclarationError,
                    "Identifier not found.",
                    _identifier.location
                ));
            success = false;
        }
        m_stackHeight += stackSize == size_t(-1) ? 1 : stackSize;
    }
    m_info.stackHeightInfo[&_identifier] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(FunctionalInstruction const& _instr)
{
    bool success = true;
    for (auto const& arg: _instr.arguments | boost::adaptors::reversed)
    {
        int const stackHeight = m_stackHeight;
        if (!boost::apply_visitor(*this, arg))
            success = false;
        if (!expectDeposit(1, stackHeight, locationOf(arg)))
            success = false;
    }
    // Parser already checks that the number of arguments is correct.
    solAssert(instructionInfo(_instr.instruction.instruction).args == int(_instr.arguments.size()), "");
    if (!(*this)(_instr.instruction))
        success = false;
    m_info.stackHeightInfo[&_instr] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(assembly::StackAssignment const& _assignment)
{
    bool success = checkAssignment(_assignment.variableName, size_t(-1));
    m_info.stackHeightInfo[&_assignment] = m_stackHeight;
    return success;
}


bool AsmAnalyzer::operator()(assembly::Assignment const& _assignment)
{
    int const stackHeight = m_stackHeight;
    bool success = boost::apply_visitor(*this, *_assignment.value);
    solAssert(m_stackHeight >= stackHeight, "Negative value size.");
    if (!checkAssignment(_assignment.variableName, m_stackHeight - stackHeight))
        success = false;
    m_info.stackHeightInfo[&_assignment] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(assembly::VariableDeclaration const& _varDecl)
{
    int const expectedItems = _varDecl.variables.size();
    int const stackHeight = m_stackHeight;
    bool success = boost::apply_visitor(*this, *_varDecl.value);
    if ((m_stackHeight - stackHeight) != expectedItems)
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::DeclarationError,
            "Variable count mismatch.",
            _varDecl.location
        ));
        return false;
    }

    for (auto const& variable: _varDecl.variables)
        boost::get<Scope::Variable>(m_currentScope->identifiers.at(variable.name)).active = true;
    m_info.stackHeightInfo[&_varDecl] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(assembly::FunctionDefinition const& _funDef)
{
    Scope& bodyScope = scope(&_funDef.body);
    for (auto const& var: _funDef.arguments + _funDef.returns)
        boost::get<Scope::Variable>(bodyScope.identifiers.at(var.name)).active = true;

    int const stackHeight = m_stackHeight;
    m_stackHeight = _funDef.arguments.size() + _funDef.returns.size();
    m_virtualVariablesInNextBlock = m_stackHeight;

    bool success = (*this)(_funDef.body);

    m_stackHeight = stackHeight;
    m_info.stackHeightInfo[&_funDef] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(assembly::FunctionCall const& _funCall)
{
    bool success = true;
    size_t arguments = 0;
    size_t returns = 0;
    if (!m_currentScope->lookup(_funCall.functionName.name, Scope::Visitor(
        [&](Scope::Variable const&)
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::TypeError,
                "Attempt to call variable instead of function.",
                _funCall.functionName.location
            ));
            success = false;
        },
        [&](Scope::Label const&)
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::TypeError,
                "Attempt to call label instead of function.",
                _funCall.functionName.location
                ));
            success = false;
        },
        [&](Scope::Function const& _fun)
        {
            /// TODO: compare types too
            arguments = _fun.arguments.size();
            returns = _fun.returns.size();
        }
    )))
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::DeclarationError,
            "Function not found.",
            _funCall.functionName.location
        ));
        success = false;
    }
    if (success)
    {
        if (_funCall.arguments.size() != arguments)
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::TypeError,
                "Expected " +
                boost::lexical_cast<string>(arguments) +
                " arguments but got " +
                boost::lexical_cast<string>(_funCall.arguments.size()) +
                ".",
                _funCall.functionName.location
                ));
            success = false;
        }
    }
    for (auto const& arg: _funCall.arguments | boost::adaptors::reversed)
    {
        int const stackHeight = m_stackHeight;
        if (!boost::apply_visitor(*this, arg))
            success = false;
        if (!expectDeposit(1, stackHeight, locationOf(arg)))
            success = false;
    }
    m_stackHeight += int(returns) - int(arguments);
    m_info.stackHeightInfo[&_funCall] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::operator()(Block const& _block)
{
    bool success = true;
    m_currentScope = &scope(&_block);

    int const initialStackHeight = m_stackHeight - m_virtualVariablesInNextBlock;
    m_virtualVariablesInNextBlock = 0;

    for (auto const& s: _block.statements)
        if (!boost::apply_visitor(*this, s))
            success = false;

    for (auto const& identifier: scope(&_block).identifiers)
        if (identifier.second.type() == typeid(Scope::Variable))
            --m_stackHeight;

    int const stackDiff = m_stackHeight - initialStackHeight;
    if (stackDiff != 0)
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::DeclarationError,
            "Unbalanced stack at the end of a block: " +
            (
                stackDiff > 0 ?
                to_string(stackDiff) + string(" surplus item(s).") :
                to_string(-stackDiff) + string(" missing item(s).")
            ),
            _block.location
        ));
        success = false;
    }

    m_currentScope = m_currentScope->superScope;
    m_info.stackHeightInfo[&_block] = m_stackHeight;
    return success;
}

bool AsmAnalyzer::checkAssignment(assembly::Identifier const& _variable, size_t _valueSize)
{
    bool success = true;
    size_t numErrorsBefore = m_errors.size();
    size_t variableSize(-1);
    if (Scope::Identifier const* var = m_currentScope->lookup(_variable.name))
    {
        // Check that it is a variable
        if (var->type() != typeid(Scope::Variable))
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::TypeError,
                "Assignment requires variable.",
                _variable.location
            ));
            success = false;
        }
        else if (!boost::get<Scope::Variable>(*var).active)
        {
            m_errors.push_back(make_shared<Error>(
                Error::Type::DeclarationError,
                "Variable " + _variable.name + " used before it was declared.",
                _variable.location
            ));
            success = false;
        }
        variableSize = 1;
    }
    else if (m_resolver)
        variableSize = m_resolver(_variable, IdentifierContext::LValue);
    if (variableSize == size_t(-1))
    {
        // Only add message if the callback did not.
        if (numErrorsBefore == m_errors.size())
            m_errors.push_back(make_shared<Error>(
                Error::Type::DeclarationError,
                "Variable not found or variable not lvalue.",
                _variable.location
            ));
        success = false;
    }
    if (_valueSize == size_t(-1))
        _valueSize = variableSize == size_t(-1) ? 1 : variableSize;

    m_stackHeight -= _valueSize;

    if (_valueSize != variableSize && variableSize != size_t(-1))
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::TypeError,
            "Variable size (" +
            to_string(variableSize) +
            ") and value size (" +
            to_string(_valueSize) +
            ") do not match.",
            _variable.location
        ));
        success = false;
    }
    return success;
}

bool AsmAnalyzer::expectDeposit(int const _deposit, int const _oldHeight, SourceLocation const& _location)
{
    int stackDiff = m_stackHeight - _oldHeight;
    if (stackDiff != _deposit)
    {
        m_errors.push_back(make_shared<Error>(
            Error::Type::TypeError,
            "Expected instruction(s) to deposit " +
            boost::lexical_cast<string>(_deposit) +
            " item(s) to the stack, but did deposit " +
            boost::lexical_cast<string>(stackDiff) +
            " item(s).",
            _location
        ));
        return false;
    }
    else
        return true;
}

Scope& AsmAnalyzer::scope(Block const* _block)
{
    solAssert(m_info.scopes.count(_block) == 1, "Scope requested but not present.");
    auto scopePtr = m_info.scopes.at(_block);
    solAssert(scopePtr, "Scope requested but not present.");
    return *scopePtr;
}