Control flow graph for Yul.

libyul/backends/evm/ControlFlowGraphBuilder.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
+/**
+ * Transformation of a Yul AST into a control flow graph.
+ */
+#pragma once
+
+#include <libyul/backends/evm/ControlFlowGraph.h>
+
+namespace solidity::yul
+{
+
+class ControlFlowGraphBuilder
+{
+public:
+	ControlFlowGraphBuilder(ControlFlowGraphBuilder const&) = delete;
+	ControlFlowGraphBuilder& operator=(ControlFlowGraphBuilder const&) = delete;
+	static std::unique_ptr<CFG> build(AsmAnalysisInfo const& _analysisInfo, Dialect const& _dialect, Block const& _block);
+
+	StackSlot operator()(Expression const& _literal);
+	StackSlot operator()(Literal const& _literal);
+	StackSlot operator()(Identifier const& _identifier);
+	StackSlot operator()(FunctionCall const&);
+
+	void operator()(VariableDeclaration const& _varDecl);
+	void operator()(Assignment const& _assignment);
+	void operator()(ExpressionStatement const& _statement);
+
+	void operator()(Block const& _block);
+
+	void operator()(If const& _if);
+	void operator()(Switch const& _switch);
+	void operator()(ForLoop const&);
+	void operator()(Break const&);
+	void operator()(Continue const&);
+	void operator()(Leave const&);
+	void operator()(FunctionDefinition const&);
+
+private:
+	ControlFlowGraphBuilder(
+		CFG& _graph,
+		AsmAnalysisInfo const& _analysisInfo,
+		Dialect const& _dialect
+	);
+	CFG::Operation const& visitFunctionCall(FunctionCall const&);
+	Stack visitAssignmentRightHandSide(Expression const& _expression, size_t _expectedSlotCount);
+
+	Scope::Function const& lookupFunction(YulString _name) const;
+	Scope::Variable const& lookupVariable(YulString _name) const;
+	/// @returns a pair of newly created blocks, the first element being the non-zero branch, the second element the
+	/// zero branch.
+	/// Resets m_currentBlock to enforce a subsequent explicit reassignment.
+	std::pair<CFG::BasicBlock*, CFG::BasicBlock*> makeConditionalJump(StackSlot _condition);
+	/// Resets m_currentBlock to enforce a subsequent explicit reassignment.
+	void makeConditionalJump(StackSlot _condition, CFG::BasicBlock& _nonZero, CFG::BasicBlock& _zero);
+	void jump(CFG::BasicBlock& _target, bool _backwards = false);
+	CFG& m_graph;
+	AsmAnalysisInfo const& m_info;
+	Dialect const& m_dialect;
+	CFG::BasicBlock* m_currentBlock = nullptr;
+	Scope* m_scope = nullptr;
+	struct ForLoopInfo
+	{
+		std::reference_wrapper<CFG::BasicBlock> afterLoop;
+		std::reference_wrapper<CFG::BasicBlock> post;
+	};
+	std::optional<ForLoopInfo> m_forLoopInfo;
+	std::optional<CFG::BasicBlock::FunctionReturn> m_currentFunctionExit;
+};
+
+}