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Fix stack shuffling.

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This commit is contained in:
Daniel Kirchner 2022-08-09 20:06:52 +02:00
parent 90d9f2d080
commit 5c0d285cab
2 changed files with 35 additions and 0 deletions
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28
libyul/backends/evm/StackHelpers.h
View File

@ -69,6 +69,8 @@ template<typename ShuffleOperations>
concept ShuffleOperationConcept = requires(ShuffleOperations ops, size_t sourceOffset, size_t targetOffset, size_t depth) {
// Returns true, iff the current slot at sourceOffset in source layout is a suitable slot at targetOffset.
{ ops.isCompatible(sourceOffset, targetOffset) } -> std::convertible_to<bool>;
// Returns true, iff the slots at the given source offset is junk.
{ ops.sourceIsJunk(sourceOffset) } -> std::convertible_to<bool>;
// Returns true, iff the slots at the two given source offsets are identical.
{ ops.sourceIsSame(sourceOffset, sourceOffset) } -> std::convertible_to<bool>;
// Returns a positive integer n, if the slot at the given source offset needs n more copies.
@ -187,6 +189,12 @@ private:
std::list<size_t> toVisit{_targetOffset};
std::set<size_t> visited;
if (_ops.targetIsArbitrary(_targetOffset))
{
_ops.pushOrDupTarget(_targetOffset);
return true;
}
while (!toVisit.empty())
{
auto offset = *toVisit.begin();
@ -314,6 +322,22 @@ private:
// If we still need more slots, produce a suitable one.
if (ops.sourceSize() < ops.targetSize())
{
// If we do not need the current top and pushing another slot would make a position we need to fix unreachable,
// pop the current top.
if (
ops.sourceSize() >= 16 &&
(ops.sourceMultiplicity(sourceTop) < 0 || ops.sourceIsJunk(sourceTop))
)
{
for (size_t sourceOffset = 0; sourceOffset < ops.sourceSize() - 16; ++sourceOffset)
if (!ops.isCompatible(sourceOffset, sourceOffset))
{
ops.pop();
return true;
}
}
if (!dupDeepSlotIfRequired(ops))
yulAssert(bringUpTargetSlot(ops, ops.sourceSize()), "");
return true;
@ -430,6 +454,10 @@ void createStackLayout(Stack& _currentStack, Stack const& _targetStack, Swap _sw
bool sourceIsSame(size_t _lhs, size_t _rhs) { return currentStack.at(_lhs) == currentStack.at(_rhs); }
int sourceMultiplicity(size_t _offset) { return multiplicity.at(currentStack.at(_offset)); }
int targetMultiplicity(size_t _offset) { return multiplicity.at(targetStack.at(_offset)); }
bool sourceIsJunk(size_t offset)
{
return std::holds_alternative<JunkSlot>(currentStack.at(offset));
}
bool targetIsArbitrary(size_t offset)
{
return offset < targetStack.size() && std::holds_alternative<JunkSlot>(targetStack.at(offset));

7
libyul/backends/evm/StackLayoutGenerator.cpp
View File

@ -206,6 +206,13 @@ Stack createIdealLayout(Stack const& _operationOutput, Stack const& _post, Calla
}, layout.at(_source))
);
}
bool sourceIsJunk(size_t offset)
{
return std::visit(util::GenericVisitor{
[&](PreviousSlot const&) { return false; },
[&](StackSlot const& _slot) { return std::holds_alternative<JunkSlot>(_slot); },
}, layout.at(offset));
}
bool sourceIsSame(size_t _lhs, size_t _rhs)
{
return std::visit(util::GenericVisitor{