solidity/libyul/backends/wasm/WordSizeTransform.cpp

364 lines
9.5 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/>.
*/
#include <libyul/AsmData.h>
#include <libyul/backends/wasm/WordSizeTransform.h>
#include <libyul/Utilities.h>
#include <libyul/Dialect.h>
#include <libyul/optimiser/NameDisplacer.h>
#include <libdevcore/CommonData.h>
#include <array>
#include <map>
using namespace std;
using namespace dev;
using namespace yul;
void WordSizeTransform::operator()(FunctionDefinition& _fd)
{
rewriteVarDeclList(_fd.parameters);
rewriteVarDeclList(_fd.returnVariables);
(*this)(_fd.body);
}
void WordSizeTransform::operator()(FunctionalInstruction& _ins)
{
rewriteFunctionCallArguments(_ins.arguments);
}
void WordSizeTransform::operator()(FunctionCall& _fc)
{
if (BuiltinFunction const* fun = m_inputDialect.builtin(_fc.functionName.name))
if (fun->literalArguments)
return;
rewriteFunctionCallArguments(_fc.arguments);
}
void WordSizeTransform::operator()(If& _if)
{
_if.condition = make_unique<Expression>(FunctionCall{
locationOf(*_if.condition),
Identifier{locationOf(*_if.condition), "or_bool"_yulstring},
expandValueToVector(*_if.condition)
});
(*this)(_if.body);
}
void WordSizeTransform::operator()(Switch&)
{
yulAssert(false, "Switch statement has to be handled inside the containing block.");
}
void WordSizeTransform::operator()(ForLoop& _for)
{
(*this)(_for.pre);
_for.condition = make_unique<Expression>(FunctionCall{
locationOf(*_for.condition),
Identifier{locationOf(*_for.condition), "or_bool"_yulstring},
expandValueToVector(*_for.condition)
});
(*this)(_for.post);
(*this)(_for.body);
}
void WordSizeTransform::operator()(Block& _block)
{
iterateReplacing(
_block.statements,
[&](Statement& _s) -> boost::optional<vector<Statement>>
{
if (_s.type() == typeid(VariableDeclaration))
{
VariableDeclaration& varDecl = boost::get<VariableDeclaration>(_s);
if (
!varDecl.value ||
varDecl.value->type() == typeid(FunctionalInstruction) ||
varDecl.value->type() == typeid(FunctionCall)
)
{
if (varDecl.value) visit(*varDecl.value);
rewriteVarDeclList(varDecl.variables);
return boost::none;
}
else if (
varDecl.value->type() == typeid(Identifier) ||
varDecl.value->type() == typeid(Literal)
)
{
yulAssert(varDecl.variables.size() == 1, "");
auto newRhs = expandValue(*varDecl.value);
auto newLhs = generateU64IdentifierNames(varDecl.variables[0].name);
vector<Statement> ret;
for (int i = 0; i < 4; i++)
ret.push_back(
VariableDeclaration{
varDecl.location,
{TypedName{varDecl.location, newLhs[i], "u64"_yulstring}},
std::move(newRhs[i])
}
);
return ret;
}
else
yulAssert(false, "");
}
else if (_s.type() == typeid(Assignment))
{
Assignment& assignment = boost::get<Assignment>(_s);
yulAssert(assignment.value, "");
if (
assignment.value->type() == typeid(FunctionalInstruction) ||
assignment.value->type() == typeid(FunctionCall)
)
{
if (assignment.value) visit(*assignment.value);
rewriteIdentifierList(assignment.variableNames);
return boost::none;
}
else if (
assignment.value->type() == typeid(Identifier) ||
assignment.value->type() == typeid(Literal)
)
{
yulAssert(assignment.variableNames.size() == 1, "");
auto newRhs = expandValue(*assignment.value);
YulString lhsName = assignment.variableNames[0].name;
vector<Statement> ret;
for (int i = 0; i < 4; i++)
ret.push_back(
Assignment{
assignment.location,
{Identifier{assignment.location, m_variableMapping.at(lhsName)[i]}},
std::move(newRhs[i])
}
);
return ret;
}
else
yulAssert(false, "");
}
else if (_s.type() == typeid(Switch))
return handleSwitch(boost::get<Switch>(_s));
else
visit(_s);
return boost::none;
}
);
}
void WordSizeTransform::run(Dialect const& _inputDialect, Block& _ast, NameDispenser& _nameDispenser)
{
// Free the name `or_bool`.
NameDisplacer{_nameDispenser, {"or_bool"_yulstring}}(_ast);
WordSizeTransform{_inputDialect, _nameDispenser}(_ast);
}
void WordSizeTransform::rewriteVarDeclList(TypedNameList& _nameList)
{
iterateReplacing(
_nameList,
[&](TypedName const& _n) -> boost::optional<TypedNameList>
{
TypedNameList ret;
for (auto newName: generateU64IdentifierNames(_n.name))
ret.emplace_back(TypedName{_n.location, newName, "u64"_yulstring});
return ret;
}
);
}
void WordSizeTransform::rewriteIdentifierList(vector<Identifier>& _ids)
{
iterateReplacing(
_ids,
[&](Identifier const& _id) -> boost::optional<vector<Identifier>>
{
vector<Identifier> ret;
for (auto newId: m_variableMapping.at(_id.name))
ret.push_back(Identifier{_id.location, newId});
return ret;
}
);
}
void WordSizeTransform::rewriteFunctionCallArguments(vector<Expression>& _args)
{
iterateReplacing(
_args,
[&](Expression& _e) -> boost::optional<vector<Expression>>
{
return expandValueToVector(_e);
}
);
}
vector<Statement> WordSizeTransform::handleSwitchInternal(
langutil::SourceLocation const& _location,
vector<YulString> const& _splitExpressions,
vector<Case> _cases,
YulString _runDefaultFlag,
size_t _depth
)
{
if (_depth == 4)
{
yulAssert(_cases.size() == 1, "");
return std::move(_cases.front().body.statements);
}
// Extract current 64 bit segment and group by it.
map<u256, vector<Case>> cases;
for (Case& c: _cases)
{
yulAssert(c.value, "Default case still present.");
cases[
(valueOfLiteral(*c.value) >> (256 - 64 * (_depth + 1))) &
std::numeric_limits<uint64_t>::max()
].emplace_back(std::move(c));
}
Switch ret{
_location,
make_unique<Expression>(Identifier{_location, _splitExpressions.at(_depth)}),
{}
};
for (auto& c: cases)
{
Literal label{_location, LiteralKind::Number, YulString(c.first.str()), "u64"_yulstring};
ret.cases.emplace_back(Case{
c.second.front().location,
make_unique<Literal>(std::move(label)),
Block{_location, handleSwitchInternal(
_location,
_splitExpressions,
std::move(c.second),
_runDefaultFlag,
_depth + 1
)}
});
}
if (!_runDefaultFlag.empty())
ret.cases.emplace_back(Case{
_location,
nullptr,
Block{_location, make_vector<Statement>(
Assignment{
_location,
{{_location, _runDefaultFlag}},
make_unique<Expression>(Literal{_location, LiteralKind::Number, "1"_yulstring, "u64"_yulstring})
}
)}
});
return make_vector<Statement>(std::move(ret));
}
std::vector<Statement> WordSizeTransform::handleSwitch(Switch& _switch)
{
for (auto& c: _switch.cases)
(*this)(c.body);
// Turns the switch into a quadruply-nested switch plus
// a flag that tells to execute the default case after all the switches.
vector<Statement> ret;
YulString runDefaultFlag;
Case defaultCase;
if (!_switch.cases.back().value)
{
runDefaultFlag = m_nameDispenser.newName("run_default"_yulstring);
defaultCase = std::move(_switch.cases.back());
_switch.cases.pop_back();
ret.emplace_back(VariableDeclaration{
_switch.location,
{TypedName{_switch.location, runDefaultFlag, "u64"_yulstring}},
{}
});
}
vector<YulString> splitExpressions;
for (auto const& expr: expandValue(*_switch.expression))
splitExpressions.emplace_back(boost::get<Identifier>(*expr).name);
ret += handleSwitchInternal(
_switch.location,
splitExpressions,
std::move(_switch.cases),
runDefaultFlag,
0
);
if (!runDefaultFlag.empty())
ret.emplace_back(If{
_switch.location,
make_unique<Expression>(Identifier{_switch.location, runDefaultFlag}),
std::move(defaultCase.body)
});
return ret;
}
array<YulString, 4> WordSizeTransform::generateU64IdentifierNames(YulString const& _s)
{
yulAssert(m_variableMapping.find(_s) == m_variableMapping.end(), "");
for (int i = 0; i < 4; i++)
m_variableMapping[_s][i] = m_nameDispenser.newName(YulString{_s.str() + "_" + to_string(i)});
return m_variableMapping[_s];
}
array<unique_ptr<Expression>, 4> WordSizeTransform::expandValue(Expression const& _e)
{
array<unique_ptr<Expression>, 4> ret;
if (_e.type() == typeid(Identifier))
{
Identifier const& id = boost::get<Identifier>(_e);
for (int i = 0; i < 4; i++)
ret[i] = make_unique<Expression>(Identifier{id.location, m_variableMapping.at(id.name)[i]});
}
else if (_e.type() == typeid(Literal))
{
Literal const& lit = boost::get<Literal>(_e);
u256 val = valueOfLiteral(lit);
for (int i = 3; i >= 0; i--)
{
u256 currentVal = val & std::numeric_limits<uint64_t>::max();
val >>= 64;
ret[i] = make_unique<Expression>(
Literal{
lit.location,
LiteralKind::Number,
YulString(currentVal.str()),
"u64"_yulstring
}
);
}
}
else
yulAssert(false, "Invalid expression to split.");
return ret;
}
vector<Expression> WordSizeTransform::expandValueToVector(Expression const& _e)
{
vector<Expression> ret;
for (unique_ptr<Expression>& val: expandValue(_e))
ret.emplace_back(std::move(*val));
return ret;
}