solidity/libyul/backends/wasm/WasmCodeTransform.cpp
2019-12-18 15:59:31 +00:00

393 lines
12 KiB
C++

/*
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/>.
*/
/**
* Common code generator for translating Yul / inline assembly to Wasm.
*/
#include <libyul/backends/wasm/WasmCodeTransform.h>
#include <libyul/optimiser/NameCollector.h>
#include <libyul/AsmData.h>
#include <libyul/Dialect.h>
#include <libyul/Utilities.h>
#include <libyul/Exceptions.h>
#include <liblangutil/Exceptions.h>
#include <boost/range/adaptor/reversed.hpp>
#include <boost/range/adaptor/transformed.hpp>
using namespace std;
using namespace dev;
using namespace yul;
wasm::Module WasmCodeTransform::run(Dialect const& _dialect, yul::Block const& _ast)
{
wasm::Module module;
WasmCodeTransform transform(_dialect, _ast);
for (auto const& statement: _ast.statements)
{
yulAssert(
holds_alternative<yul::FunctionDefinition>(statement),
"Expected only function definitions at the highest level."
);
if (holds_alternative<yul::FunctionDefinition>(statement))
module.functions.emplace_back(transform.translateFunction(std::get<yul::FunctionDefinition>(statement)));
}
for (auto& imp: transform.m_functionsToImport)
module.imports.emplace_back(std::move(imp.second));
module.globals = transform.m_globalVariables;
return module;
}
wasm::Expression WasmCodeTransform::generateMultiAssignment(
vector<string> _variableNames,
unique_ptr<wasm::Expression> _firstValue
)
{
yulAssert(!_variableNames.empty(), "");
wasm::LocalAssignment assignment{move(_variableNames.front()), std::move(_firstValue)};
if (_variableNames.size() == 1)
return { std::move(assignment) };
allocateGlobals(_variableNames.size() - 1);
wasm::Block block;
block.statements.emplace_back(move(assignment));
for (size_t i = 1; i < _variableNames.size(); ++i)
block.statements.emplace_back(wasm::LocalAssignment{
move(_variableNames.at(i)),
make_unique<wasm::Expression>(wasm::GlobalVariable{m_globalVariables.at(i - 1).variableName})
});
return { std::move(block) };
}
wasm::Expression WasmCodeTransform::operator()(VariableDeclaration const& _varDecl)
{
vector<string> variableNames;
for (auto const& var: _varDecl.variables)
{
variableNames.emplace_back(var.name.str());
m_localVariables.emplace_back(wasm::VariableDeclaration{variableNames.back()});
}
if (_varDecl.value)
return generateMultiAssignment(move(variableNames), visit(*_varDecl.value));
else
return wasm::BuiltinCall{"nop", {}};
}
wasm::Expression WasmCodeTransform::operator()(Assignment const& _assignment)
{
vector<string> variableNames;
for (auto const& var: _assignment.variableNames)
variableNames.emplace_back(var.name.str());
return generateMultiAssignment(move(variableNames), visit(*_assignment.value));
}
wasm::Expression WasmCodeTransform::operator()(ExpressionStatement const& _statement)
{
return visitReturnByValue(_statement.expression);
}
wasm::Expression WasmCodeTransform::operator()(FunctionCall const& _call)
{
bool typeConversionNeeded = false;
if (BuiltinFunction const* builtin = m_dialect.builtin(_call.functionName.name))
{
if (_call.functionName.name.str().substr(0, 4) == "eth.")
{
yulAssert(builtin->returns.size() <= 1, "");
// Imported function, use regular call, but mark for import.
if (!m_functionsToImport.count(builtin->name))
{
wasm::FunctionImport imp{
"ethereum",
builtin->name.str().substr(4),
builtin->name.str(),
{},
builtin->returns.empty() ? nullptr : make_unique<string>(builtin->returns.front().str())
};
for (auto const& param: builtin->parameters)
imp.paramTypes.emplace_back(param.str());
m_functionsToImport[builtin->name] = std::move(imp);
}
typeConversionNeeded = true;
}
else if (builtin->literalArguments)
{
vector<wasm::Expression> literals;
for (auto const& arg: _call.arguments)
literals.emplace_back(wasm::StringLiteral{std::get<Literal>(arg).value.str()});
return wasm::BuiltinCall{_call.functionName.name.str(), std::move(literals)};
}
else
{
wasm::BuiltinCall call{
_call.functionName.name.str(),
injectTypeConversionIfNeeded(visit(_call.arguments), builtin->parameters)
};
if (!builtin->returns.empty() && !builtin->returns.front().empty() && builtin->returns.front() != "i64"_yulstring)
{
yulAssert(builtin->returns.front() == "i32"_yulstring, "Invalid type " + builtin->returns.front().str());
call = wasm::BuiltinCall{"i64.extend_i32_u", make_vector<wasm::Expression>(std::move(call))};
}
return {std::move(call)};
}
}
// If this function returns multiple values, then the first one will
// be returned in the expression itself and the others in global variables.
// The values have to be used right away in an assignment or variable declaration,
// so it is handled there.
wasm::FunctionCall funCall{_call.functionName.name.str(), visit(_call.arguments)};
if (typeConversionNeeded)
// Inject type conversion if needed on the fly. This is just a temporary measure
// and can be removed once we have proper types in Yul.
return injectTypeConversionIfNeeded(std::move(funCall));
else
return {std::move(funCall)};
}
wasm::Expression WasmCodeTransform::operator()(Identifier const& _identifier)
{
return wasm::LocalVariable{_identifier.name.str()};
}
wasm::Expression WasmCodeTransform::operator()(Literal const& _literal)
{
u256 value = valueOfLiteral(_literal);
yulAssert(value <= numeric_limits<uint64_t>::max(), "Literal too large: " + value.str());
return wasm::Literal{uint64_t(value)};
}
wasm::Expression WasmCodeTransform::operator()(If const& _if)
{
// TODO converting i64 to i32 might not always be needed.
vector<wasm::Expression> args;
args.emplace_back(visitReturnByValue(*_if.condition));
args.emplace_back(wasm::Literal{0});
return wasm::If{
make_unique<wasm::Expression>(wasm::BuiltinCall{"i64.ne", std::move(args)}),
visit(_if.body.statements),
{}
};
}
wasm::Expression WasmCodeTransform::operator()(Switch const& _switch)
{
wasm::Block block;
string condition = m_nameDispenser.newName("condition"_yulstring).str();
m_localVariables.emplace_back(wasm::VariableDeclaration{condition});
block.statements.emplace_back(wasm::LocalAssignment{condition, visit(*_switch.expression)});
vector<wasm::Expression>* currentBlock = &block.statements;
for (size_t i = 0; i < _switch.cases.size(); ++i)
{
Case const& c = _switch.cases.at(i);
if (c.value)
{
wasm::BuiltinCall comparison{"i64.eq", make_vector<wasm::Expression>(
wasm::LocalVariable{condition},
visitReturnByValue(*c.value)
)};
wasm::If ifStmnt{
make_unique<wasm::Expression>(move(comparison)),
visit(c.body.statements),
{}
};
vector<wasm::Expression>* nextBlock = nullptr;
if (i != _switch.cases.size() - 1)
{
ifStmnt.elseStatements = make_unique<vector<wasm::Expression>>();
nextBlock = ifStmnt.elseStatements.get();
}
currentBlock->emplace_back(move(ifStmnt));
currentBlock = nextBlock;
}
else
{
yulAssert(i == _switch.cases.size() - 1, "Default case must be last.");
*currentBlock += visit(c.body.statements);
}
}
return { std::move(block) };
}
wasm::Expression WasmCodeTransform::operator()(FunctionDefinition const&)
{
yulAssert(false, "Should not have visited here.");
return {};
}
wasm::Expression WasmCodeTransform::operator()(ForLoop const& _for)
{
string breakLabel = newLabel();
string continueLabel = newLabel();
m_breakContinueLabelNames.push({breakLabel, continueLabel});
wasm::Loop loop;
loop.statements = visit(_for.pre.statements);
loop.statements.emplace_back(wasm::BreakIf{wasm::Label{breakLabel}, make_unique<wasm::Expression>(
wasm::BuiltinCall{"i64.eqz", make_vector<wasm::Expression>(
visitReturnByValue(*_for.condition)
)}
)});
loop.statements.emplace_back(wasm::Block{continueLabel, visit(_for.body.statements)});
loop.statements += visit(_for.post.statements);
return { wasm::Block{breakLabel, make_vector<wasm::Expression>(move(loop))} };
}
wasm::Expression WasmCodeTransform::operator()(Break const&)
{
return wasm::Break{wasm::Label{m_breakContinueLabelNames.top().first}};
}
wasm::Expression WasmCodeTransform::operator()(Continue const&)
{
return wasm::Break{wasm::Label{m_breakContinueLabelNames.top().second}};
}
wasm::Expression WasmCodeTransform::operator()(Leave const&)
{
return wasm::Return{};
}
wasm::Expression WasmCodeTransform::operator()(Block const& _block)
{
return wasm::Block{{}, visit(_block.statements)};
}
unique_ptr<wasm::Expression> WasmCodeTransform::visit(yul::Expression const& _expression)
{
return make_unique<wasm::Expression>(std::visit(*this, _expression));
}
wasm::Expression WasmCodeTransform::visitReturnByValue(yul::Expression const& _expression)
{
return std::visit(*this, _expression);
}
vector<wasm::Expression> WasmCodeTransform::visit(vector<yul::Expression> const& _expressions)
{
vector<wasm::Expression> ret;
for (auto const& e: _expressions)
ret.emplace_back(visitReturnByValue(e));
return ret;
}
wasm::Expression WasmCodeTransform::visit(yul::Statement const& _statement)
{
return std::visit(*this, _statement);
}
vector<wasm::Expression> WasmCodeTransform::visit(vector<yul::Statement> const& _statements)
{
vector<wasm::Expression> ret;
for (auto const& s: _statements)
ret.emplace_back(visit(s));
return ret;
}
wasm::FunctionDefinition WasmCodeTransform::translateFunction(yul::FunctionDefinition const& _fun)
{
wasm::FunctionDefinition fun;
fun.name = _fun.name.str();
for (auto const& param: _fun.parameters)
fun.parameterNames.emplace_back(param.name.str());
for (auto const& retParam: _fun.returnVariables)
fun.locals.emplace_back(wasm::VariableDeclaration{retParam.name.str()});
fun.returns = !_fun.returnVariables.empty();
yulAssert(m_localVariables.empty(), "");
fun.body = visit(_fun.body.statements);
fun.locals += m_localVariables;
m_localVariables.clear();
if (!_fun.returnVariables.empty())
{
// First return variable is returned directly, the others are stored
// in globals.
allocateGlobals(_fun.returnVariables.size() - 1);
for (size_t i = 1; i < _fun.returnVariables.size(); ++i)
fun.body.emplace_back(wasm::GlobalAssignment{
m_globalVariables.at(i - 1).variableName,
make_unique<wasm::Expression>(wasm::LocalVariable{_fun.returnVariables.at(i).name.str()})
});
fun.body.emplace_back(wasm::LocalVariable{_fun.returnVariables.front().name.str()});
}
return fun;
}
wasm::Expression WasmCodeTransform::injectTypeConversionIfNeeded(wasm::FunctionCall _call) const
{
wasm::FunctionImport const& import = m_functionsToImport.at(YulString{_call.functionName});
for (size_t i = 0; i < _call.arguments.size(); ++i)
if (import.paramTypes.at(i) == "i32")
_call.arguments[i] = wasm::BuiltinCall{"i32.wrap_i64", make_vector<wasm::Expression>(std::move(_call.arguments[i]))};
else
yulAssert(import.paramTypes.at(i) == "i64", "Unknown type " + import.paramTypes.at(i));
if (import.returnType && *import.returnType != "i64")
{
yulAssert(*import.returnType == "i32", "Invalid type " + *import.returnType);
return wasm::BuiltinCall{"i64.extend_i32_u", make_vector<wasm::Expression>(std::move(_call))};
}
return {std::move(_call)};
}
vector<wasm::Expression> WasmCodeTransform::injectTypeConversionIfNeeded(
vector<wasm::Expression> _arguments,
vector<Type> const& _parameterTypes
) const
{
for (size_t i = 0; i < _arguments.size(); ++i)
if (_parameterTypes.at(i) == "i32"_yulstring)
_arguments[i] = wasm::BuiltinCall{"i32.wrap_i64", make_vector<wasm::Expression>(std::move(_arguments[i]))};
else
yulAssert(
_parameterTypes.at(i).empty() || _parameterTypes.at(i) == "i64"_yulstring,
"Unknown type " + _parameterTypes.at(i).str()
);
return _arguments;
}
string WasmCodeTransform::newLabel()
{
return m_nameDispenser.newName("label_"_yulstring).str();
}
void WasmCodeTransform::allocateGlobals(size_t _amount)
{
while (m_globalVariables.size() < _amount)
m_globalVariables.emplace_back(wasm::GlobalVariableDeclaration{
m_nameDispenser.newName("global_"_yulstring).str()
});
}