Control flow side-effects for user-defined functions.

libyul/ControlFlowSideEffectsCollector.h

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+/*
+	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/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+#pragma once
+
+#include <libyul/optimiser/ASTWalker.h>
+#include <libyul/ControlFlowSideEffects.h>
+
+#include <set>
+#include <stack>
+#include <optional>
+#include <list>
+
+namespace solidity::yul
+{
+
+struct Dialect;
+
+struct ControlFlowNode
+{
+	std::vector<ControlFlowNode const*> successors;
+	/// Name of the called function if the node calls a function.
+	std::optional<YulString> functionCall;
+};
+
+/**
+ * The control flow of a function with entry and exit nodes.
+ */
+struct FunctionFlow
+{
+	ControlFlowNode const* entry;
+	ControlFlowNode const* exit;
+};
+
+/**
+ * Requires: Disambiguator, Function Hoister.
+ */
+class ControlFlowBuilder: private ASTWalker
+{
+public:
+	/// Computes the control-flows of all function defined in the block.
+	/// Assumes the functions are hoisted to the topmost block.
+	explicit ControlFlowBuilder(Block const& _ast);
+	std::map<YulString, FunctionFlow> const& functionFlows() const { return m_functionFlows; }
+
+private:
+	using ASTWalker::operator();
+	void operator()(FunctionCall const& _functionCall) override;
+	void operator()(If const& _if) override;
+	void operator()(Switch const& _switch) override;
+	void operator()(FunctionDefinition const& _functionDefinition) override;
+	void operator()(ForLoop const& _forLoop) override;
+	void operator()(Break const& _break) override;
+	void operator()(Continue const& _continue) override;
+	void operator()(Leave const& _leaveStatement) override;
+
+	void newConnectedNode();
+	ControlFlowNode* newNode();
+
+	std::vector<std::shared_ptr<ControlFlowNode>> m_nodes;
+
+	ControlFlowNode* m_currentNode = nullptr;
+	ControlFlowNode const* m_leave = nullptr;
+	ControlFlowNode const* m_break = nullptr;
+	ControlFlowNode const* m_continue = nullptr;
+
+	std::map<YulString, FunctionFlow> m_functionFlows;
+};
+
+
+/**
+ * Requires: Disambiguator, Function Hoister.
+ */
+class ControlFlowSideEffectsCollector
+{
+public:
+	explicit ControlFlowSideEffectsCollector(
+		Dialect const& _dialect,
+		Block const& _ast
+	);
+
+	std::map<YulString, ControlFlowSideEffects> const& functionSideEffects() const
+	{
+		return m_functionSideEffects;
+	}
+private:
+
+	/// @returns false if nothing could be processed.
+	bool processFunction(YulString _name);
+
+	/// @returns the next pending node of the function that is not
+	/// a function call to a function that might not continue.
+	/// De-queues the node or returns nullptr if no such node is found.
+	ControlFlowNode const* nextProcessableNode(YulString _functionName);
+
+	/// @returns the side-effects of either a builtin call or a user defined function
+	/// call (as far as already computed).
+	ControlFlowSideEffects const& sideEffects(YulString _functionName) const;
+
+	/// Queues the given node to be processed (if not already visited)
+	/// and if it is a function call, records that `_functionName` calls
+	/// `*_node->functionCall`.
+	void recordReachabilityAndQueue(YulString _functionName, ControlFlowNode const* _node);
+
+	Dialect const& m_dialect;
+	ControlFlowBuilder m_cfgBuilder;
+	std::map<YulString, ControlFlowSideEffects> m_functionSideEffects;
+	std::map<YulString, std::list<ControlFlowNode const*>> m_pendingNodes;
+	std::map<YulString, std::set<ControlFlowNode const*>> m_processedNodes;
+	/// `x` is in `m_functionCalls[y]` if a direct call to `x` is reachable inside `y`
+	std::map<YulString, std::set<YulString>> m_functionCalls;
+};
+
+
+}