Function findStackTooDeep

libyul/backends/evm/StackLayoutGenerator.cpp:118–162

@returns all stack too deep errors that would occur when shuffling @a _source to @a _target.

{
/// @returns all stack too deep errors that would occur when shuffling @a _source to @a _target.
std::vector<StackLayoutGenerator::StackTooDeep> findStackTooDeep(
	Stack const& _source,
	Stack const& _target,
	size_t _reachableStackDepth
)
{
	Stack currentStack = _source;
	std::vector<StackLayoutGenerator::StackTooDeep> stackTooDeepErrors;
	auto getVariableChoices = [](auto&& _range) {
		std::vector<YulName> result;
		for (auto const& slot: _range)
			if (auto const* variableSlot = std::get_if<VariableSlot>(&slot))
				if (!util::contains(result, variableSlot->variable.get().name))
					result.push_back(variableSlot->variable.get().name);
		return result;
	};
	::createStackLayout(
		currentStack,
		_target,
		[&](unsigned _i)
		{
			if (_i > _reachableStackDepth)
				stackTooDeepErrors.emplace_back(StackLayoutGenerator::StackTooDeep{
					_i - _reachableStackDepth,
					getVariableChoices(currentStack | ranges::views::take_last(_i + 1))
				});
		},
		[&](StackSlot const& _slot)
		{
			if (canBeFreelyGenerated(_slot))
				return;
			if (
				auto depth = util::findOffset(currentStack | ranges::views::reverse, _slot);
				depth && *depth >= _reachableStackDepth
			)
				stackTooDeepErrors.emplace_back(StackLayoutGenerator::StackTooDeep{
					*depth - (_reachableStackDepth - 1),
					getVariableChoices(currentStack | ranges::views::take_last(*depth + 1))
				});
		},
		[&]() {},
		_reachableStackDepth
	);
	return stackTooDeepErrors;
}

/// @returns the ideal stack to have before executing an operation that outputs @a _operationOutput, s.t.
/// shuffling to @a _post is cheap (excluding the input of the operation itself).