Merge pull request #12082 from ethereum/controlFlowSideEffectsUserDefined

Control flow side effects of user defined functions

libsolidity/analysis/ControlFlowBuilder.cpp

@@ -533,14 +533,14 @@ void ControlFlowBuilder::operator()(yul::FunctionCall const& _functionCall)
 	yul::ASTWalker::operator()(_functionCall);
 
 	if (auto const *builtinFunction = m_inlineAssembly->dialect().builtin(_functionCall.functionName.name))
-		if (builtinFunction->controlFlowSideEffects.terminates)
-		{
-			if (builtinFunction->controlFlowSideEffects.reverts)
-				connect(m_currentNode, m_revertNode);
-			else
-				connect(m_currentNode, m_transactionReturnNode);
+	{
+		if (builtinFunction->controlFlowSideEffects.canTerminate)
+			connect(m_currentNode, m_transactionReturnNode);
+		if (builtinFunction->controlFlowSideEffects.canRevert)
+			connect(m_currentNode, m_revertNode);
+		if (!builtinFunction->controlFlowSideEffects.canContinue)
 			m_currentNode = newLabel();
-		}
+	}
 }
 
 void ControlFlowBuilder::operator()(yul::FunctionDefinition const&)

libyul/CMakeLists.txt

@@ -34,6 +34,9 @@ add_library(yul
 	AssemblyStack.cpp
 	CompilabilityChecker.cpp
 	CompilabilityChecker.h
+	ControlFlowSideEffects.h
+	ControlFlowSideEffectsCollector.cpp
+	ControlFlowSideEffectsCollector.h
 	Dialect.cpp
 	Dialect.h
 	Exceptions.h

libyul/ControlFlowSideEffects.h

@@ -18,22 +18,32 @@
 
 #pragma once
 
-#include <set>
-
 namespace solidity::yul
 {
 
 /**
- * Side effects of code related to control flow.
+ * Side effects of a user-defined or builtin function.
+ *
+ * Each of the three booleans represents a reachability condition. There is an implied
+ * fourth alternative, which is going out of gas while executing the function. Since
+ * this can always happen and depends on the supply of gas, it is not considered.
+ *
+ * If all three booleans are false, it means that the function always leads to infinite
+ * recursion.
  */
 struct ControlFlowSideEffects
 {
-	/// If true, this code terminates the control flow.
-	/// State may or may not be reverted as indicated by the ``reverts`` flag.
-	bool terminates = false;
-	/// If true, this code reverts all state changes in the transaction.
-	/// Whenever this is true, ``terminates`` has to be true as well.
-	bool reverts = false;
+	/// If true, the function contains at least one reachable branch that terminates successfully.
+	bool canTerminate = false;
+	/// If true, the function contains at least one reachable branch that reverts.
+	bool canRevert = false;
+	/// If true, the function has a regular outgoing control-flow.
+	bool canContinue = true;
+
+	bool terminatesOrReverts() const
+	{
+		return (canTerminate || canRevert) && !canContinue;
+	}
 };
 
 }

libyul/ControlFlowSideEffectsCollector.cpp

@@ -0,0 +1,274 @@
+/*
+	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
+
+#include <libyul/ControlFlowSideEffectsCollector.h>
+
+#include <libyul/optimiser/FunctionDefinitionCollector.h>
+
+#include <libyul/AST.h>
+#include <libyul/Dialect.h>
+
+#include <libsolutil/Common.h>
+#include <libsolutil/CommonData.h>
+#include <libsolutil/Algorithms.h>
+
+#include <range/v3/view/map.hpp>
+#include <range/v3/view/reverse.hpp>
+#include <range/v3/algorithm/find_if.hpp>
+
+using namespace std;
+using namespace solidity::yul;
+
+
+ControlFlowBuilder::ControlFlowBuilder(Block const& _ast)
+{
+	for (auto const& statement: _ast.statements)
+		if (auto const* function = get_if<FunctionDefinition>(&statement))
+			(*this)(*function);
+}
+
+void ControlFlowBuilder::operator()(FunctionCall const& _functionCall)
+{
+	walkVector(_functionCall.arguments | ranges::views::reverse);
+	newConnectedNode();
+	m_currentNode->functionCall = _functionCall.functionName.name;
+}
+
+void ControlFlowBuilder::operator()(If const& _if)
+{
+	visit(*_if.condition);
+	ControlFlowNode* node = m_currentNode;
+	(*this)(_if.body);
+	newConnectedNode();
+	node->successors.emplace_back(m_currentNode);
+}
+
+void ControlFlowBuilder::operator()(Switch const& _switch)
+{
+	visit(*_switch.expression);
+	ControlFlowNode* initialNode = m_currentNode;
+	ControlFlowNode* finalNode = newNode();
+
+	if (_switch.cases.back().value)
+		initialNode->successors.emplace_back(finalNode);
+
+	for (Case const& case_: _switch.cases)
+	{
+		m_currentNode = initialNode;
+		(*this)(case_.body);
+		newConnectedNode();
+		m_currentNode->successors.emplace_back(finalNode);
+	}
+	m_currentNode = finalNode;
+}
+
+void ControlFlowBuilder::operator()(FunctionDefinition const& _function)
+{
+	ScopedSaveAndRestore currentNode(m_currentNode, nullptr);
+	yulAssert(!m_leave && !m_break && !m_continue, "Function hoister has not been used.");
+
+	FunctionFlow flow;
+	flow.exit = newNode();
+	m_currentNode = newNode();
+	flow.entry = m_currentNode;
+	m_leave = flow.exit;
+
+	(*this)(_function.body);
+
+	m_currentNode->successors.emplace_back(flow.exit);
+
+	m_functionFlows[_function.name] = move(flow);
+
+	m_leave = nullptr;
+}
+
+void ControlFlowBuilder::operator()(ForLoop const& _for)
+{
+	ScopedSaveAndRestore scopedBreakNode(m_break, nullptr);
+	ScopedSaveAndRestore scopedContinueNode(m_continue, nullptr);
+
+	(*this)(_for.pre);
+
+	ControlFlowNode* breakNode = newNode();
+	m_break = breakNode;
+	ControlFlowNode* continueNode = newNode();
+	m_continue = continueNode;
+
+	newConnectedNode();
+	ControlFlowNode* loopNode = m_currentNode;
+	visit(*_for.condition);
+	m_currentNode->successors.emplace_back(m_break);
+	newConnectedNode();
+
+	(*this)(_for.body);
+
+	m_currentNode->successors.emplace_back(m_continue);
+	m_currentNode = continueNode;
+
+	(*this)(_for.post);
+	m_currentNode->successors.emplace_back(loopNode);
+
+	m_currentNode = breakNode;
+}
+
+void ControlFlowBuilder::operator()(Break const&)
+{
+	yulAssert(m_break);
+	m_currentNode->successors.emplace_back(m_break);
+	m_currentNode = newNode();
+}
+
+void ControlFlowBuilder::operator()(Continue const&)
+{
+	yulAssert(m_continue);
+	m_currentNode->successors.emplace_back(m_continue);
+	m_currentNode = newNode();
+}
+
+void ControlFlowBuilder::operator()(Leave const&)
+{
+	yulAssert(m_leave);
+	m_currentNode->successors.emplace_back(m_leave);
+	m_currentNode = newNode();
+}
+
+void ControlFlowBuilder::newConnectedNode()
+{
+	ControlFlowNode* node = newNode();
+	m_currentNode->successors.emplace_back(node);
+	m_currentNode = node;
+}
+
+ControlFlowNode* ControlFlowBuilder::newNode()
+{
+	m_nodes.emplace_back(make_shared<ControlFlowNode>());
+	return m_nodes.back().get();
+}
+
+
+ControlFlowSideEffectsCollector::ControlFlowSideEffectsCollector(
+	Dialect const& _dialect,
+	Block const& _ast
+):
+	m_dialect(_dialect),
+	m_cfgBuilder(_ast)
+{
+	for (auto&& [name, flow]: m_cfgBuilder.functionFlows())
+	{
+		yulAssert(!flow.entry->functionCall);
+		m_processedNodes[name] = {};
+		m_pendingNodes[name].push_front(flow.entry);
+		m_functionSideEffects[name] = {false, false, false};
+	}
+
+	// Process functions while we have progress. For now, we are only interested
+	// in `canContinue`.
+	bool progress = true;
+	while (progress)
+	{
+		progress = false;
+		for (auto const& functionName: m_pendingNodes | ranges::views::keys)
+			if (processFunction(functionName))
+				progress = true;
+	}
+
+	// No progress anymore: All remaining nodes are calls
+	// to functions that always recurse.
+	// If we have not set `canContinue` by now, the function's exit
+	// is not reachable.
+
+	for (auto&& [functionName, calls]: m_functionCalls)
+	{
+		ControlFlowSideEffects& sideEffects = m_functionSideEffects[functionName];
+		auto _visit = [&, visited = std::set<YulString>{}](YulString _function, auto&& _recurse) mutable {
+			if (sideEffects.canTerminate && sideEffects.canRevert)
+				return;
+			if (!visited.insert(_function).second)
+				return;
+
+			ControlFlowSideEffects const* calledSideEffects = nullptr;
+			if (BuiltinFunction const* f = _dialect.builtin(_function))
+				calledSideEffects = &f->controlFlowSideEffects;
+			else
+				calledSideEffects = &m_functionSideEffects.at(_function);
+
+			if (calledSideEffects->canTerminate)
+				sideEffects.canTerminate = true;
+			if (calledSideEffects->canRevert)
+				sideEffects.canRevert = true;
+
+			for (YulString callee: util::valueOrDefault(m_functionCalls, _function))
+				_recurse(callee, _recurse);
+		};
+		for (auto const& call: calls)
+			_visit(call, _visit);
+	}
+
+}
+
+bool ControlFlowSideEffectsCollector::processFunction(YulString _name)
+{
+	bool progress = false;
+	while (ControlFlowNode const* node = nextProcessableNode(_name))
+	{
+		if (node == m_cfgBuilder.functionFlows().at(_name).exit)
+		{
+			m_functionSideEffects[_name].canContinue = true;
+			return true;
+		}
+		for (ControlFlowNode const* s: node->successors)
+			recordReachabilityAndQueue(_name, s);
+
+		progress = true;
+	}
+	return progress;
+}
+
+ControlFlowNode const* ControlFlowSideEffectsCollector::nextProcessableNode(YulString _functionName)
+{
+	std::list<ControlFlowNode const*>& nodes = m_pendingNodes[_functionName];
+	auto it = ranges::find_if(nodes, [this](ControlFlowNode const* _node) {
+		return !_node->functionCall || sideEffects(*_node->functionCall).canContinue;
+	});
+	if (it == nodes.end())
+		return nullptr;
+
+	ControlFlowNode const* node = *it;
+	nodes.erase(it);
+	return node;
+}
+
+ControlFlowSideEffects const& ControlFlowSideEffectsCollector::sideEffects(YulString _functionName) const
+{
+	if (auto const* builtin = m_dialect.builtin(_functionName))
+		return builtin->controlFlowSideEffects;
+	else
+		return m_functionSideEffects.at(_functionName);
+}
+
+void ControlFlowSideEffectsCollector::recordReachabilityAndQueue(
+	YulString _functionName,
+	ControlFlowNode const* _node
+)
+{
+	if (_node->functionCall)
+		m_functionCalls[_functionName].insert(*_node->functionCall);
+	if (m_processedNodes[_functionName].insert(_node).second)
+		m_pendingNodes.at(_functionName).push_front(_node);
+}
+

libyul/ControlFlowSideEffectsCollector.h

@@ -0,0 +1,130 @@
+/*
+	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;
+};
+
+
+}

libyul/Dialect.h

@@ -22,8 +22,8 @@
 #pragma once
 
 #include <libyul/YulString.h>
-#include <libyul/SideEffects.h>
 #include <libyul/ControlFlowSideEffects.h>
+#include <libyul/SideEffects.h>
 
 #include <vector>
 #include <set>

libyul/SideEffects.h

@@ -94,7 +94,7 @@ struct SideEffects
 			cannotLoop && _other.cannotLoop,
 			otherState + _other.otherState,
 			storage + _other.storage,
-			memory +  _other.memory
+			memory + _other.memory
 		};
 	}
 

libyul/backends/evm/ControlFlowGraphBuilder.cpp

@@ -229,7 +229,7 @@ void ControlFlowGraphBuilder::operator()(ExpressionStatement const& _exprStmt)
 	//       not only for builtins.
 	if (auto const* funCall = get_if<FunctionCall>(&_exprStmt.expression))
 		if (BuiltinFunction const* builtin = m_dialect.builtin(funCall->functionName.name))
-			if (builtin->controlFlowSideEffects.terminates)
+			if (builtin->controlFlowSideEffects.terminatesOrReverts())
 			{
 				m_currentBlock->exit = CFG::BasicBlock::Terminated{};
 				m_currentBlock = &m_graph.makeBlock(debugDataOf(*m_currentBlock));

libyul/backends/evm/EVMDialect.cpp

@@ -57,8 +57,20 @@ pair<YulString, BuiltinFunctionForEVM> createEVMFunction(
 	f.parameters.resize(static_cast<size_t>(info.args));
 	f.returns.resize(static_cast<size_t>(info.ret));
 	f.sideEffects = EVMDialect::sideEffectsOfInstruction(_instruction);
-	f.controlFlowSideEffects.terminates = evmasm::SemanticInformation::terminatesControlFlow(_instruction);
-	f.controlFlowSideEffects.reverts = evmasm::SemanticInformation::reverts(_instruction);
+	if (evmasm::SemanticInformation::terminatesControlFlow(_instruction))
+	{
+		f.controlFlowSideEffects.canContinue = false;
+		if (evmasm::SemanticInformation::reverts(_instruction))
+		{
+			f.controlFlowSideEffects.canTerminate = false;
+			f.controlFlowSideEffects.canRevert = true;
+		}
+		else
+		{
+			f.controlFlowSideEffects.canTerminate = true;
+			f.controlFlowSideEffects.canRevert = false;
+		}
+	}
 	f.isMSize = _instruction == evmasm::Instruction::MSIZE;
 	f.literalArguments.clear();
 	f.instruction = _instruction;

libyul/backends/evm/OptimizedEVMCodeTransform.cpp

@@ -484,7 +484,7 @@ void OptimizedEVMCodeTransform::operator()(CFG::BasicBlock const& _block)
 			yulAssert(!_block.operations.empty(), "");
 			CFG::BuiltinCall const* builtinCall = get_if<CFG::BuiltinCall>(&_block.operations.back().operation);
 			yulAssert(builtinCall, "");
-			yulAssert(builtinCall->builtin.get().controlFlowSideEffects.terminates, "");
+			yulAssert(builtinCall->builtin.get().controlFlowSideEffects.terminatesOrReverts(), "");
 		}
 	}, _block.exit);
 	// TODO: We could assert that the last emitted assembly item terminated or was an (unconditional) jump.

libyul/backends/wasm/WasmDialect.cpp

@@ -129,8 +129,9 @@ WasmDialect::WasmDialect()
 	m_functions["unreachable"_yulstring].sideEffects.storage = SideEffects::None;
 	m_functions["unreachable"_yulstring].sideEffects.memory = SideEffects::None;
 	m_functions["unreachable"_yulstring].sideEffects.otherState = SideEffects::None;
-	m_functions["unreachable"_yulstring].controlFlowSideEffects.terminates = true;
-	m_functions["unreachable"_yulstring].controlFlowSideEffects.reverts = true;
+	m_functions["unreachable"_yulstring].controlFlowSideEffects.canTerminate = false;
+	m_functions["unreachable"_yulstring].controlFlowSideEffects.canRevert = true;
+	m_functions["unreachable"_yulstring].controlFlowSideEffects.canContinue = false;
 
 	addFunction("datasize", {i64}, {i64}, true, {LiteralKind::String});
 	addFunction("dataoffset", {i64}, {i64}, true, {LiteralKind::String});
@@ -215,11 +216,11 @@ void WasmDialect::addExternals()
 		{"eth", "log", {i32ptr, i32, i32, i32ptr, i32ptr, i32ptr, i32ptr}, {}},
 		{"eth", "getBlockNumber", {}, {i64}},
 		{"eth", "getTxOrigin", {i32ptr}, {}},
-		{"eth", "finish", {i32ptr, i32}, {}, ControlFlowSideEffects{true, false}},
-		{"eth", "revert", {i32ptr, i32}, {}, ControlFlowSideEffects{true, true}},
+		{"eth", "finish", {i32ptr, i32}, {}, ControlFlowSideEffects{true, false, false}},
+		{"eth", "revert", {i32ptr, i32}, {}, ControlFlowSideEffects{false, true, false}},
 		{"eth", "getReturnDataSize", {}, {i32}},
 		{"eth", "returnDataCopy", {i32ptr, i32, i32}, {}},
-		{"eth", "selfDestruct", {i32ptr}, {}, ControlFlowSideEffects{true, false}},
+		{"eth", "selfDestruct", {i32ptr}, {}, ControlFlowSideEffects{false, true, false}},
 		{"eth", "getBlockTimestamp", {}, {i64}},
 		{"debug", "print32", {i32}, {}},
 		{"debug", "print64", {i64}, {}},
@@ -240,7 +241,7 @@ void WasmDialect::addExternals()
 		// TODO some of them are side effect free.
 		f.sideEffects = SideEffects::worst();
 		f.sideEffects.cannotLoop = true;
-		f.sideEffects.movableApartFromEffects = !ext.controlFlowSideEffects.terminates;
+		f.sideEffects.movableApartFromEffects = !ext.controlFlowSideEffects.terminatesOrReverts();
 		f.controlFlowSideEffects = ext.controlFlowSideEffects;
 		f.isMSize = false;
 		f.literalArguments.clear();

libyul/optimiser/FunctionDefinitionCollector.cpp

@@ -22,7 +22,7 @@ using namespace std;
 using namespace solidity;
 using namespace solidity::yul;
 
-map<YulString, FunctionDefinition const*> FunctionDefinitionCollector::run(Block& _block)
+map<YulString, FunctionDefinition const*> FunctionDefinitionCollector::run(Block const& _block)
 {
 	FunctionDefinitionCollector functionDefinitionCollector;
 	functionDefinitionCollector(_block);

libyul/optimiser/FunctionDefinitionCollector.h

@@ -34,7 +34,7 @@ namespace solidity::yul
 class FunctionDefinitionCollector: ASTWalker
 {
 public:
-	static std::map<YulString, FunctionDefinition const*> run(Block& _block);
+	static std::map<YulString, FunctionDefinition const*> run(Block const& _block);
 private:
 	using ASTWalker::operator();
 	void operator()(FunctionDefinition const& _functionDefinition) override;

test/CMakeLists.txt

@@ -130,6 +130,8 @@ set(libyul_sources
     libyul/CompilabilityChecker.cpp
     libyul/ControlFlowGraphTest.cpp
     libyul/ControlFlowGraphTest.h
+    libyul/ControlFlowSideEffectsTest.cpp
+    libyul/ControlFlowSideEffectsTest.h
     libyul/EVMCodeTransformTest.cpp
     libyul/EVMCodeTransformTest.h
     libyul/EwasmTranslationTest.cpp

test/InteractiveTests.h

@@ -31,6 +31,7 @@
 #include <test/libyul/YulOptimizerTest.h>
 #include <test/libyul/YulInterpreterTest.h>
 #include <test/libyul/ObjectCompilerTest.h>
+#include <test/libyul/ControlFlowSideEffectsTest.h>
 #include <test/libyul/FunctionSideEffects.h>
 #include <test/libyul/StackLayoutGeneratorTest.h>
 #include <test/libyul/SyntaxTest.h>
@@ -57,12 +58,12 @@ struct Testsuite
 Testsuite const g_interactiveTestsuites[] = {
 /*
 	Title                   Path           Subpath                SMT   NeedsVM Creator function */
-	{"Ewasm Translation",      "libyul",      "ewasmTranslationTests", false, false, &yul::test::EwasmTranslationTest::create},
 	{"Yul Optimizer",          "libyul",      "yulOptimizerTests",     false, false, &yul::test::YulOptimizerTest::create},
 	{"Yul Interpreter",        "libyul",      "yulInterpreterTests",   false, false, &yul::test::YulInterpreterTest::create},
 	{"Yul Object Compiler",    "libyul",      "objectCompiler",        false, false, &yul::test::ObjectCompilerTest::create},
 	{"Yul Control Flow Graph", "libyul",      "yulControlFlowGraph",   false, false, &yul::test::ControlFlowGraphTest::create},
 	{"Yul Stack Layout",       "libyul",      "yulStackLayout",        false, false, &yul::test::StackLayoutGeneratorTest::create},
+	{"Control Flow Side Effects","libyul",    "controlFlowSideEffects",false, false, &yul::test::ControlFlowSideEffectsTest::create},
 	{"Function Side Effects",  "libyul",      "functionSideEffects",   false, false, &yul::test::FunctionSideEffects::create},
 	{"Yul Syntax",             "libyul",      "yulSyntaxTests",        false, false, &yul::test::SyntaxTest::create},
 	{"EVM Code Transform",     "libyul",      "evmCodeTransform",      false, false, &yul::test::EVMCodeTransformTest::create, {"nooptions"}},
@@ -72,7 +73,8 @@ Testsuite const g_interactiveTestsuites[] = {
 	{"JSON AST",               "libsolidity", "ASTJSON",               false, false, &ASTJSONTest::create},
 	{"JSON ABI",               "libsolidity", "ABIJson",               false, false, &ABIJsonTest::create},
 	{"SMT Checker",            "libsolidity", "smtCheckerTests",       true,  false, &SMTCheckerTest::create},
-	{"Gas Estimates",          "libsolidity", "gasTests",              false, false, &GasTest::create}
+	{"Gas Estimates",          "libsolidity", "gasTests",              false, false, &GasTest::create},
+	{"Ewasm Translation",      "libyul",      "ewasmTranslationTests", false, false, &yul::test::EwasmTranslationTest::create}
 };
 
 }

test/libyul/ControlFlowSideEffectsTest.cpp

@@ -0,0 +1,79 @@
+/*
+	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
+
+#include <test/libyul/ControlFlowSideEffectsTest.h>
+
+#include <test/Common.h>
+#include <test/libyul/Common.h>
+
+#include <libyul/Object.h>
+#include <libyul/ControlFlowSideEffects.h>
+#include <libyul/ControlFlowSideEffectsCollector.h>
+#include <libyul/backends/evm/EVMDialect.h>
+
+using namespace std;
+using namespace solidity;
+using namespace solidity::yul;
+using namespace solidity::yul::test;
+using namespace solidity::frontend::test;
+
+namespace
+{
+string toString(ControlFlowSideEffects const& _sideEffects)
+{
+	vector<string> r;
+	if (_sideEffects.canTerminate)
+		r.emplace_back("can terminate");
+	if (_sideEffects.canRevert)
+		r.emplace_back("can revert");
+	if (_sideEffects.canContinue)
+		r.emplace_back("can continue");
+	return util::joinHumanReadable(r);
+}
+}
+
+ControlFlowSideEffectsTest::ControlFlowSideEffectsTest(string const& _filename):
+	TestCase(_filename)
+{
+	m_source = m_reader.source();
+	m_expectation = m_reader.simpleExpectations();
+}
+
+TestCase::TestResult ControlFlowSideEffectsTest::run(ostream& _stream, string const& _linePrefix, bool _formatted)
+{
+	Object obj;
+	std::tie(obj.code, obj.analysisInfo) = yul::test::parse(m_source, false);
+	if (!obj.code)
+		BOOST_THROW_EXCEPTION(runtime_error("Parsing input failed."));
+
+	std::map<YulString, ControlFlowSideEffects> sideEffects =
+		ControlFlowSideEffectsCollector(
+			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion()),
+			*obj.code
+		).functionSideEffects();
+
+	std::map<std::string, std::string> controlFlowSideEffectsStr;
+	for (auto&& [fun, effects]: sideEffects)
+		controlFlowSideEffectsStr[fun.str()] = toString(effects);
+
+	m_obtainedResult.clear();
+	for (auto&& [functionName, effect]: controlFlowSideEffectsStr)
+		m_obtainedResult += functionName + (effect.empty() ? ":" : ": " + effect) + "\n";
+
+	return checkResult(_stream, _linePrefix, _formatted);
+}

test/libyul/ControlFlowSideEffectsTest.h

@@ -0,0 +1,40 @@
+/*
+	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 <test/TestCase.h>
+
+#include <iosfwd>
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace solidity::yul::test
+{
+
+class ControlFlowSideEffectsTest: public solidity::frontend::test::TestCase
+{
+public:
+	static std::unique_ptr<TestCase> create(Config const& _config)
+	{ return std::make_unique<ControlFlowSideEffectsTest>(_config.filename); }
+	explicit ControlFlowSideEffectsTest(std::string const& _filename);
+	TestResult run(std::ostream& _stream, std::string const& _linePrefix = "", bool const _formatted = false) override;
+};
+
+}

test/libyul/controlFlowSideEffects/eval_order.yul

@@ -0,0 +1,19 @@
+{
+    function a() -> x {
+        revert(0, 0)
+    }
+    function b() -> x {
+        return(0, 0)
+    }
+    function c() {
+        sstore(a(), b())
+    }
+    function d() {
+        sstore(b(), a())
+    }
+}
+// ----
+// a: can revert
+// b: can terminate
+// c: can terminate
+// d: can revert

test/libyul/controlFlowSideEffects/for_loop.yul

@@ -0,0 +1,55 @@
+{
+    function a() {
+        for { leave } calldataload(0) { } {
+            break
+            revert(0, 0)
+        }
+    }
+    function b() {
+        for { } calldataload(0) { leave } {
+            break
+            revert(0, 0)
+        }
+    }
+    function b2() {
+        for { } calldataload(0) { leave } {
+            revert(0, 0)
+        }
+    }
+    function c() {
+        for { } calldataload(0) { revert(0, 0) } {
+            break
+        }
+    }
+    function c2() {
+        for { } calldataload(0) { revert(0, 0) } {
+            break
+            revert(0, 0)
+        }
+    }
+    function d() {
+        for { } calldataload(0) { revert(0, 0) } {
+            continue
+        }
+    }
+    function e() {
+        for { } calldataload(0) { revert(0, 0) } {
+            if calldataload(1) { break }
+        }
+    }
+    function f() {
+        for { } calldataload(0) {  } {
+            if calldataload(1) { continue }
+            revert(0, 0)
+        }
+    }
+}
+// ----
+// a: can continue
+// b: can continue
+// b2: can revert, can continue
+// c: can continue
+// c2: can continue
+// d: can revert, can continue
+// e: can revert, can continue
+// f: can revert, can continue

test/libyul/controlFlowSideEffects/leave.yul

@@ -0,0 +1,13 @@
+{
+    function a() {
+        revert(0, 0)
+        leave
+    }
+    function b() {
+        leave
+        revert(0, 0)
+    }
+}
+// ----
+// a: can revert
+// b: can continue

test/libyul/controlFlowSideEffects/recursion.yul

@@ -0,0 +1,37 @@
+{
+    function a() {
+        if calldataload(0) {
+            revert(0, 0)
+        }
+        reg()
+        b()
+    }
+    function b() {
+        a()
+        return(0, 0)
+    }
+    function c() {
+        c()
+        revert(0, 0)
+    }
+    function d() {
+        switch calldataload(0)
+        case 0 { x() }
+        case 1 { y() reg() revert(0, 0) }
+        default { z() }
+    }
+    function x() { d() revert(0, 0) }
+    function y() { reg() x() }
+    function z() { y() }
+
+    function reg() {}
+}
+// ----
+// a: can revert
+// b: can revert
+// c:
+// d:
+// reg: can continue
+// x:
+// y:
+// z:

test/libyul/controlFlowSideEffects/simple_conditionals.yul

@@ -0,0 +1,34 @@
+{
+    function a() {
+        if calldataload(0) { g() }
+    }
+    function b() {
+        g()
+        if calldataload(0) { }
+    }
+    function c() {
+        if calldataload(0) { }
+        g()
+    }
+    function d() {
+        stop()
+        if calldataload(0) { g() }
+    }
+    function e() {
+        if calldataload(0) { g() }
+        stop()
+    }
+    function f() {
+        g()
+        if calldataload(0) { g() }
+    }
+    function g() { revert(0, 0) }
+}
+// ----
+// a: can revert, can continue
+// b: can revert
+// c: can revert
+// d: can terminate
+// e: can terminate, can revert
+// f: can revert
+// g: can revert

test/libyul/controlFlowSideEffects/simple_functions.yul

@@ -0,0 +1,17 @@
+{
+    function a() {}
+    function f() { g() }
+    function g() { revert(0, 0) }
+    function h() { stop() }
+    function i() { h() }
+    function j() { h() g() }
+    function k() { g() h() }
+}
+// ----
+// a: can continue
+// f: can revert
+// g: can revert
+// h: can terminate
+// i: can terminate
+// j: can terminate
+// k: can revert

test/libyul/controlFlowSideEffects/switch.yul

@@ -0,0 +1,41 @@
+{
+    function a() {
+        switch calldataload(0)
+        case 0 { revert(0, 0) }
+    }
+    function b() {
+        switch calldataload(0)
+        case 0 { revert(0, 0) }
+        default { revert(0, 0) }
+    }
+    function c() {
+        return(0, 0)
+        switch calldataload(0)
+        case 0 { revert(0, 0) }
+        default { }
+    }
+    function d() {
+        switch calldataload(0)
+        case 0 { return(0, 0) }
+        default { return(0, 0) }
+        revert(0, 0)
+    }
+    function e() {
+        switch calldataload(0)
+        case 0 { return(0, 0) }
+        revert(0, 0)
+    }
+    function f() {
+        switch calldataload(0)
+        case 0 { leave }
+        default { leave }
+        revert(0, 0)
+    }
+}
+// ----
+// a: can revert, can continue
+// b: can revert
+// c: can terminate
+// d: can terminate
+// e: can terminate, can revert
+// f: can continue

test/tools/CMakeLists.txt

@@ -33,6 +33,7 @@ add_executable(isoltest
 	../libsolidity/SMTCheckerTest.cpp
 	../libyul/Common.cpp
 	../libyul/ControlFlowGraphTest.cpp
+	../libyul/ControlFlowSideEffectsTest.cpp
 	../libyul/EVMCodeTransformTest.cpp
 	../libyul/EwasmTranslationTest.cpp
 	../libyul/FunctionSideEffects.cpp