ControlFlowAnalyser: Also consider called functions in a flow

libsolidity/analysis/ControlFlowRevertPruner.h

@@ -0,0 +1,87 @@
+/*
+	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 <libsolidity/ast/AST.h>
+#include <libsolidity/analysis/ControlFlowGraph.h>
+
+#include <libsolutil/Algorithms.h>
+
+namespace solidity::frontend
+{
+
+/**
+ * Analyses all function flows and recursively removes all exit edges from CFG
+ * nodes that make function calls that will always revert.
+ */
+class ControlFlowRevertPruner
+{
+public:
+	ControlFlowRevertPruner(CFG& _cfg): m_cfg(_cfg) {}
+
+	void run();
+private:
+	/// Possible revert states of a function call
+	enum class RevertState
+	{
+		AllPathsRevert,
+		HasNonRevertingPath,
+		Unknown,
+	};
+
+	/// Simple attempt at resolving a function call
+	/// Does not aim to be able to resolve all calls, only used for variable
+	/// assignment tracking and revert behavior.
+	/// @param _functionCall the function call to analyse
+	/// @param _mostDerivedContract most derived contract
+	/// @returns function definition to which the call resolved or nullptr if no
+	///          definition was found.
+	FunctionDefinition const* resolveCall(FunctionCall const& _functionCall, ContractDefinition const* _mostDerivedContract);
+
+	/// Identify revert states of all function flows
+	void findRevertStates();
+
+	/// Modify function flows so that edges with reverting function calls are removed
+	void modifyFunctionFlows();
+
+
+	/// Collect all function calls made by `_function` for later analysis
+	/// @param _function function to analyse
+	/// @param _mostDerivedContract most derived contract used in the calls
+	void collectCalls(FunctionDefinition const& _function, ContractDefinition const* _mostDerivedContract);
+
+	/// Control Flow Graph object.
+	CFG& m_cfg;
+
+	/// function/contract pairs mapped to their according revert state
+	std::map<CFG::FunctionContractTuple, RevertState> m_functions;
+
+	/// Called function mapped to the set of function/contract pairs calling them
+	std::map<
+		FunctionDefinition const*,
+		std::set<CFG::FunctionContractTuple>
+	> m_calledBy;
+
+	std::map<
+		std::tuple<FunctionCall const*, ContractDefinition const*>,
+		FunctionDefinition const*
+	> m_resolveCache;
+
+};
+}