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Merge pull request #9961 from ethereum/stackLimitEvaderRefactor2

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StackToMemoryMover: encapsulate memory offset tracking into its own class.
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chriseth 2020-10-08 19:56:44 +02:00 committed by GitHub
commit d513e05ce9
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2 changed files with 63 additions and 49 deletions
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82
libyul/optimiser/StackToMemoryMover.cpp
View File

@ -59,20 +59,17 @@ void StackToMemoryMover::run(
Block& _block
)
{
StackToMemoryMover stackToMemoryMover(_context, _reservedMemory, _memorySlots, _numRequiredSlots);
VariableMemoryOffsetTracker memoryOffsetTracker(_reservedMemory, _memorySlots, _numRequiredSlots);
StackToMemoryMover stackToMemoryMover(_context, memoryOffsetTracker);
stackToMemoryMover(_block);
}
StackToMemoryMover::StackToMemoryMover(
OptimiserStepContext& _context,
u256 _reservedMemory,
map<YulString, uint64_t> const& _memorySlots,
uint64_t _numRequiredSlots
VariableMemoryOffsetTracker const& _memoryOffsetTracker
):
m_context(_context),
m_reservedMemory(std::move(_reservedMemory)),
m_memorySlots(_memorySlots),
m_numRequiredSlots(_numRequiredSlots),
m_memoryOffsetTracker(_memoryOffsetTracker),
m_nameDispenser(_context.dispenser)
{
auto const* evmDialect = dynamic_cast<EVMDialect const*>(&_context.dialect);
@ -85,7 +82,7 @@ m_nameDispenser(_context.dispenser)
void StackToMemoryMover::operator()(FunctionDefinition& _functionDefinition)
{
for (TypedName const& param: _functionDefinition.parameters + _functionDefinition.returnVariables)
if (m_memorySlots.count(param.name))
if (m_memoryOffsetTracker(param.name))
{
// TODO: we cannot handle function parameters yet.
return;
@ -98,7 +95,7 @@ void StackToMemoryMover::operator()(Block& _block)
using OptionalStatements = std::optional<vector<Statement>>;
auto containsVariableNeedingEscalation = [&](auto const& _variables) {
return util::contains_if(_variables, [&](auto const& var) {
return m_memorySlots.count(var.name);
return m_memoryOffsetTracker(var.name);
});
};
auto rewriteAssignmentOrVariableDeclaration = [&](
@ -107,12 +104,16 @@ void StackToMemoryMover::operator()(Block& _block)
std::unique_ptr<Expression> _value
) -> std::vector<Statement> {
if (_variables.size() == 1)
{
optional<YulString> offset = m_memoryOffsetTracker(_variables.front().name);
yulAssert(offset, "");
return generateMemoryStore(
m_context.dialect,
_loc,
memoryOffset(_variables.front().name),
*offset,
_value ? *std::move(_value) : Literal{_loc, LiteralKind::Number, "0"_yulstring, {}}
);
}
VariableDeclaration tempDecl{_loc, {}, std::move(_value)};
vector<Statement> memoryAssignments;
@ -122,11 +123,11 @@ void StackToMemoryMover::operator()(Block& _block)
YulString tempVarName = m_nameDispenser.newName(var.name);
tempDecl.variables.emplace_back(TypedName{var.location, tempVarName, {}});
if (m_memorySlots.count(var.name))
if (optional<YulString> offset = m_memoryOffsetTracker(var.name))
memoryAssignments += generateMemoryStore(
m_context.dialect,
_loc,
memoryOffset(var.name),
*offset,
Identifier{_loc, tempVarName}
);
else if constexpr (std::is_same_v<std::decay_t<decltype(var)>, Identifier>)
@ -185,35 +186,36 @@ void StackToMemoryMover::operator()(Block& _block)
void StackToMemoryMover::visit(Expression& _expression)
{
if (
Identifier* identifier = std::get_if<Identifier>(&_expression);
identifier && m_memorySlots.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),
{}
if (Identifier* identifier = std::get_if<Identifier>(&_expression))
if (optional<YulString> offset = m_memoryOffsetTracker(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,
*offset,
{}
}
}
}
};
};
return;
}
ASTModifier::visit(_expression);
}
optional<YulString> StackToMemoryMover::VariableMemoryOffsetTracker::operator()(YulString _variable) const
{
if (m_memorySlots.count(_variable))
{
uint64_t slot = m_memorySlots.at(_variable);
yulAssert(slot < m_numRequiredSlots, "");
return YulString{util::toCompactHexWithPrefix(m_reservedMemory + 32 * (m_numRequiredSlots - slot - 1))};
}
else
ASTModifier::visit(_expression);
return std::nullopt;
}
YulString StackToMemoryMover::memoryOffset(YulString _variable)
{
yulAssert(m_memorySlots.count(_variable), "");
uint64_t slot = m_memorySlots.at(_variable);
yulAssert(slot < m_numRequiredSlots, "");
return YulString{util::toCompactHexWithPrefix(m_reservedMemory + 32 * (m_numRequiredSlots - slot - 1))};
}

30
libyul/optimiser/StackToMemoryMover.h
View File

@ -100,20 +100,32 @@ public:
void operator()(Block& _block) override;
void visit(Expression& _expression) override;
private:
class VariableMemoryOffsetTracker
{
public:
VariableMemoryOffsetTracker(
u256 _reservedMemory,
std::map<YulString, uint64_t> const& _memorySlots,
uint64_t _numRequiredSlots
): m_reservedMemory(_reservedMemory), m_memorySlots(_memorySlots), m_numRequiredSlots(_numRequiredSlots)
{}
/// @returns a YulString containing the memory offset to be assigned to @a _variable as number literal
/// or std::nullopt if the variable should not be moved.
std::optional<YulString> operator()(YulString _variable) const;
private:
u256 m_reservedMemory;
std::map<YulString, uint64_t> const& m_memorySlots;
uint64_t m_numRequiredSlots = 0;
};
StackToMemoryMover(
OptimiserStepContext& _context,
u256 _reservedMemory,
std::map<YulString, uint64_t> const& _memorySlots,
uint64_t _numRequiredSlots
VariableMemoryOffsetTracker const& _memoryOffsetTracker
);
/// @returns a YulString containing the memory offset to be assigned to @a _variable as number literal.
YulString memoryOffset(YulString _variable);
OptimiserStepContext& m_context;
u256 m_reservedMemory;
std::map<YulString, uint64_t> const& m_memorySlots;
uint64_t m_numRequiredSlots = 0;
VariableMemoryOffsetTracker const& m_memoryOffsetTracker;
NameDispenser& m_nameDispenser;
};