solidity/libyul/optimiser/StackToMemoryMover.cpp
2020-09-17 22:13:27 +02:00

236 lines
7.2 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/optimiser/StackToMemoryMover.h>
#include <libyul/optimiser/NameDispenser.h>
#include <libyul/backends/evm/EVMDialect.h>
#include <libyul/AsmData.h>
#include <libsolutil/CommonData.h>
#include <libsolutil/Visitor.h>
using namespace std;
using namespace solidity;
using namespace solidity::yul;
namespace
{
vector<Statement> generateMemoryStore(
Dialect const& _dialect,
langutil::SourceLocation const& _loc,
YulString _mpos,
Expression _value
)
{
BuiltinFunction const* memoryStoreFunction = _dialect.memoryStoreFunction(_dialect.defaultType);
yulAssert(memoryStoreFunction, "");
vector<Statement> result;
result.emplace_back(ExpressionStatement{_loc, FunctionCall{
_loc,
Identifier{_loc, memoryStoreFunction->name},
{
Literal{_loc, LiteralKind::Number, _mpos, {}},
std::move(_value)
}
}});
return result;
}
}
void StackToMemoryMover::run(
OptimiserStepContext& _context,
u256 _reservedMemory,
map<YulString, map<YulString, uint64_t>> const& _memorySlots,
uint64_t _numRequiredSlots,
Block& _block
)
{
StackToMemoryMover stackToMemoryMover(_context, _reservedMemory, _memorySlots, _numRequiredSlots);
stackToMemoryMover(_block);
}
StackToMemoryMover::StackToMemoryMover(
OptimiserStepContext& _context,
u256 _reservedMemory,
map<YulString, map<YulString, uint64_t>> const& _memorySlots,
uint64_t _numRequiredSlots
):
m_context(_context),
m_reservedMemory(std::move(_reservedMemory)),
m_memorySlots(_memorySlots),
m_numRequiredSlots(_numRequiredSlots),
m_nameDispenser(_context.dispenser)
{
auto const* evmDialect = dynamic_cast<EVMDialect const*>(&_context.dialect);
yulAssert(
evmDialect && evmDialect->providesObjectAccess(),
"StackToMemoryMover can only be run on objects using the EVMDialect with object access."
);
if (m_memorySlots.count(YulString{}))
// If the global scope contains variables to be moved, start with those as if it were a function.
m_currentFunctionMemorySlots = &m_memorySlots.at(YulString{});
}
void StackToMemoryMover::operator()(FunctionDefinition& _functionDefinition)
{
if (m_memorySlots.count(_functionDefinition.name))
{
map<YulString, uint64_t> const* saved = m_currentFunctionMemorySlots;
m_currentFunctionMemorySlots = &m_memorySlots.at(_functionDefinition.name);
for (TypedName const& param: _functionDefinition.parameters + _functionDefinition.returnVariables)
if (m_currentFunctionMemorySlots->count(param.name))
{
// TODO: we cannot handle function parameters yet.
m_currentFunctionMemorySlots = saved;
return;
}
ASTModifier::operator()(_functionDefinition);
m_currentFunctionMemorySlots = saved;
}
}
void StackToMemoryMover::operator()(Block& _block)
{
using OptionalStatements = std::optional<vector<Statement>>;
if (!m_currentFunctionMemorySlots)
{
ASTModifier::operator()(_block);
return;
}
auto containsVariableNeedingEscalation = [&](auto const& _variables) {
return util::contains_if(_variables, [&](auto const& var) {
return m_currentFunctionMemorySlots->count(var.name);
});
};
auto rewriteAssignmentOrVariableDeclaration = [&](
langutil::SourceLocation const& _loc,
auto const& _variables,
std::unique_ptr<Expression> _value
) -> std::vector<Statement> {
if (_variables.size() == 1)
return generateMemoryStore(
m_context.dialect,
_loc,
memoryOffset(_variables.front().name),
_value ? *std::move(_value) : Literal{_loc, LiteralKind::Number, "0"_yulstring, {}}
);
VariableDeclaration tempDecl{_loc, {}, std::move(_value)};
vector<Statement> memoryAssignments;
vector<Statement> variableAssignments;
for (auto& var: _variables)
{
YulString tempVarName = m_nameDispenser.newName(var.name);
tempDecl.variables.emplace_back(TypedName{var.location, tempVarName, {}});
if (m_currentFunctionMemorySlots->count(var.name))
memoryAssignments += generateMemoryStore(
m_context.dialect,
_loc,
memoryOffset(var.name),
Identifier{_loc, tempVarName}
);
else if constexpr (std::is_same_v<std::decay_t<decltype(var)>, Identifier>)
variableAssignments.emplace_back(Assignment{
_loc, { Identifier{var.location, var.name} },
make_unique<Expression>(Identifier{_loc, tempVarName})
});
else
variableAssignments.emplace_back(VariableDeclaration{
_loc, {std::move(var)},
make_unique<Expression>(Identifier{_loc, tempVarName})
});
}
std::vector<Statement> result;
result.emplace_back(std::move(tempDecl));
std::reverse(memoryAssignments.begin(), memoryAssignments.end());
result += std::move(memoryAssignments);
std::reverse(variableAssignments.begin(), variableAssignments.end());
result += std::move(variableAssignments);
return result;
};
util::iterateReplacing(
_block.statements,
[&](Statement& _statement)
{
auto defaultVisit = [&]() { ASTModifier::visit(_statement); return OptionalStatements{}; };
return std::visit(util::GenericVisitor{
[&](Assignment& _assignment) -> OptionalStatements
{
if (!containsVariableNeedingEscalation(_assignment.variableNames))
return defaultVisit();
visit(*_assignment.value);
return {rewriteAssignmentOrVariableDeclaration(
_assignment.location,
_assignment.variableNames,
std::move(_assignment.value)
)};
},
[&](VariableDeclaration& _varDecl) -> OptionalStatements
{
if (!containsVariableNeedingEscalation(_varDecl.variables))
return defaultVisit();
if (_varDecl.value)
visit(*_varDecl.value);
return {rewriteAssignmentOrVariableDeclaration(
_varDecl.location,
_varDecl.variables,
std::move(_varDecl.value)
)};
},
[&](auto&) { return defaultVisit(); }
}, _statement);
});
}
void StackToMemoryMover::visit(Expression& _expression)
{
if (
Identifier* identifier = std::get_if<Identifier>(&_expression);
identifier && m_currentFunctionMemorySlots && m_currentFunctionMemorySlots->count(identifier->name)
)
{
BuiltinFunction const* memoryLoadFunction = m_context.dialect.memoryLoadFunction(m_context.dialect.defaultType);
yulAssert(memoryLoadFunction, "");
langutil::SourceLocation loc = identifier->location;
_expression = FunctionCall{
loc,
Identifier{loc, memoryLoadFunction->name}, {
Literal{
loc,
LiteralKind::Number,
memoryOffset(identifier->name),
{}
}
}
};
}
else
ASTModifier::visit(_expression);
}
YulString StackToMemoryMover::memoryOffset(YulString _variable)
{
yulAssert(m_currentFunctionMemorySlots, "");
uint64_t slot = m_currentFunctionMemorySlots->at(_variable);
yulAssert(slot < m_numRequiredSlots, "");
return YulString{util::toCompactHexWithPrefix(m_reservedMemory + 32 * (m_numRequiredSlots - slot - 1))};
}