Merge pull request #13283 from ethereum/yulDebugger

Yul Debugger

libevmasm/Instruction.h

@@ -188,6 +188,21 @@ enum class Instruction: uint8_t
 	SELFDESTRUCT = 0xff	///< halt execution and register account for later deletion
 };
 
+/// @returns true if the instruction is of the CALL opcode family
+constexpr bool isCallInstruction(Instruction _inst) noexcept
+{
+	switch (_inst)
+	{
+		case Instruction::CALL:
+		case Instruction::CALLCODE:
+		case Instruction::DELEGATECALL:
+		case Instruction::STATICCALL:
+			return true;
+		default:
+			return false;
+	}
+}
+
 /// @returns true if the instruction is a PUSH
 inline bool isPushInstruction(Instruction _inst)
 {

test/libyul/EwasmTranslationTest.cpp

@@ -112,6 +112,7 @@ string EwasmTranslationTest::interpret()
 			state,
 			WasmDialect{},
 			*m_object->code,
+			/*disableExternalCalls=*/true,
 			/*disableMemoryTracing=*/false
 		);
 	}

test/libyul/YulInterpreterTest.cpp

@@ -51,6 +51,7 @@ YulInterpreterTest::YulInterpreterTest(string const& _filename):
 {
 	m_source = m_reader.source();
 	m_expectation = m_reader.simpleExpectations();
+	m_simulateExternalCallsToSelf = m_reader.boolSetting("simulateExternalCall", false);
 }
 
 TestCase::TestResult YulInterpreterTest::run(ostream& _stream, string const& _linePrefix, bool const _formatted)
@@ -98,7 +99,8 @@ string YulInterpreterTest::interpret()
 			state,
 			EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion{}),
 			*m_ast,
-			/*disableMemoryTracing=*/false
+			/*disableExternalCalls=*/ !m_simulateExternalCallsToSelf,
+			/*disableMemoryTracing=*/ false
 		);
 	}
 	catch (InterpreterTerminatedGeneric const&)

test/libyul/YulInterpreterTest.h

@@ -47,6 +47,7 @@ private:
 
 	std::shared_ptr<Block> m_ast;
 	std::shared_ptr<AsmAnalysisInfo> m_analysisInfo;
+	bool m_simulateExternalCallsToSelf = false;
 };
 
 }

test/libyul/yulInterpreterTests/external_call_to_self.yul

@@ -0,0 +1,22 @@
+{
+	mstore(0x40, 0x42)
+
+	if iszero(calldatasize()) {
+		let x := call(gas(), address(), 0, 0x40, 0x20, 0x100, 0x20)
+		sstore(0x64, calldataload(0))
+		sstore(0x100, x)
+		return(0x0, 0)
+	}
+	return(0x40, 0x20)
+}
+// ====
+// simulateExternalCall: true
+// ----
+// Trace:
+//   CALL(153, 0x11111111, 0, 64, 32, 256, 32)
+//   RETURN(0, 0)
+// Memory dump:
+//     40: 0000000000000000000000000000000000000000000000000000000000000042
+//    100: 0000000000000000000000000000000000000000000000000000000000000042
+// Storage dump:
+//   0000000000000000000000000000000000000000000000000000000000000100: 0000000000000000000000000000000000000000000000000000000000000001

test/libyul/yulInterpreterTests/external_call_unexecuted.yul

@@ -1,6 +1,6 @@
 {
 	let x := call(gas(), 0x45, 0x5, 0, 0x20, 0x30, 0x20)
-	sstore(100, x)
+	sstore(0x64, x)
 }
 // ----
 // Trace:

test/libyul/yulInterpreterTests/external_callcode_unexecuted.yul

@@ -0,0 +1,10 @@
+{
+	let x := callcode(gas(), 0x45, 0x5, 0, 0x20, 0x30, 0x20)
+	sstore(100, x)
+}
+// ----
+// Trace:
+//   CALLCODE(153, 69, 5, 0, 32, 48, 32)
+// Memory dump:
+// Storage dump:
+//   0000000000000000000000000000000000000000000000000000000000000064: 0000000000000000000000000000000000000000000000000000000000000001

test/libyul/yulInterpreterTests/external_delegatecall_unexecuted.yul

@@ -0,0 +1,10 @@
+{
+	let x := delegatecall(gas(), 0x45, 0, 0x20, 0x30, 0x20)
+	sstore(100, x)
+}
+// ----
+// Trace:
+//   DELEGATECALL(153, 69, 0, 32, 48, 32)
+// Memory dump:
+// Storage dump:
+//   0000000000000000000000000000000000000000000000000000000000000064: 0000000000000000000000000000000000000000000000000000000000000001

test/libyul/yulInterpreterTests/external_staticcall_unexecuted.yul

@@ -0,0 +1,12 @@
+{
+	let x := staticcall(gas(), 0x45, 0, 0x20, 0x30, 0x20)
+	sstore(0x64, x)
+}
+// ====
+// EVMVersion: >=byzantium
+// ----
+// Trace:
+//   STATICCALL(153, 69, 0, 32, 48, 32)
+// Memory dump:
+// Storage dump:
+//   0000000000000000000000000000000000000000000000000000000000000064: 0000000000000000000000000000000000000000000000000000000000000001

test/tools/ossfuzz/yulFuzzerCommon.cpp

@@ -53,7 +53,7 @@ yulFuzzerUtil::TerminationReason yulFuzzerUtil::interpret(
 	TerminationReason reason = TerminationReason::None;
 	try
 	{
-		Interpreter::run(state, _dialect, *_ast, _disableMemoryTracing);
+		Interpreter::run(state, _dialect, *_ast, true, _disableMemoryTracing);
 	}
 	catch (StepLimitReached const&)
 	{

test/tools/yulInterpreter/CMakeLists.txt

@@ -5,6 +5,8 @@ set(sources
 	EwasmBuiltinInterpreter.cpp
 	Interpreter.h
 	Interpreter.cpp
+	Inspector.h
+	Inspector.cpp
 )
 
 add_library(yulInterpreter ${sources})

test/tools/yulInterpreter/EVMInstructionInterpreter.cpp

@@ -70,6 +70,10 @@ u256 readZeroExtended(bytes const& _data, u256 const& _offset)
 	}
 }
 
+}
+
+namespace solidity::yul::test
+{
 /// Copy @a _size bytes of @a _source at offset @a _sourceOffset to
 /// @a _target at offset @a _targetOffset. Behaves as if @a _source would
 /// continue with an infinite sequence of zero bytes beyond its end.
@@ -185,7 +189,7 @@ u256 EVMInstructionInterpreter::eval(
 			return u256("0x1234cafe1234cafe1234cafe") + arg[0];
 		uint64_t offset = uint64_t(arg[0] & uint64_t(-1));
 		uint64_t size = uint64_t(arg[1] & uint64_t(-1));
-		return u256(keccak256(readMemory(offset, size)));
+		return u256(keccak256(m_state.readMemory(offset, size)));
 	}
 	case Instruction::ADDRESS:
 		return h256(m_state.address, h256::AlignRight);
@@ -322,24 +326,34 @@ u256 EVMInstructionInterpreter::eval(
 		return (0xdddddd + arg[1]) & u256("0xffffffffffffffffffffffffffffffffffffffff");
 	case Instruction::CALL:
 	case Instruction::CALLCODE:
-		// TODO assign returndata
 		accessMemory(arg[3], arg[4]);
 		accessMemory(arg[5], arg[6]);
 		logTrace(_instruction, arg);
-		return arg[0] & 1;
+		// Randomly fail based on the called address if it isn't a call to self.
+		// Used for fuzzing.
+		return (
+			(arg[0] > 0) &&
+			(arg[1] == util::h160::Arith(m_state.address) || (arg[1] & 1))
+		) ? 1 : 0;
 	case Instruction::DELEGATECALL:
 	case Instruction::STATICCALL:
 		accessMemory(arg[2], arg[3]);
 		accessMemory(arg[4], arg[5]);
 		logTrace(_instruction, arg);
-		return 0;
+
+		// Randomly fail based on the called address if it isn't a call to self.
+		// Used for fuzzing.
+		return (
+			(arg[0] > 0) &&
+			(arg[1] == util::h160::Arith(m_state.address) || (arg[1] & 1))
+		) ? 1 : 0;
 	case Instruction::RETURN:
 	{
-		bytes data;
+		m_state.returndata = {};
 		if (accessMemory(arg[0], arg[1]))
-			data = readMemory(arg[0], arg[1]);
+			m_state.returndata = m_state.readMemory(arg[0], arg[1]);
-		logTrace(_instruction, arg, data);
+		logTrace(_instruction, arg, m_state.returndata);
-		BOOST_THROW_EXCEPTION(ExplicitlyTerminated());
+		BOOST_THROW_EXCEPTION(ExplicitlyTerminatedWithReturn());
 	}
 	case Instruction::REVERT:
 		accessMemory(arg[0], arg[1]);
@@ -475,6 +489,8 @@ u256 EVMInstructionInterpreter::evalBuiltin(
 			);
 		return 0;
 	}
+	else if (fun == "memoryguard")
+		return _evaluatedArguments.at(0);
 	else
 		yulAssert(false, "Unknown builtin: " + fun);
 	return 0;
@@ -497,18 +513,9 @@ bool EVMInstructionInterpreter::accessMemory(u256 const& _offset, u256 const& _s
 	return false;
 }
 
-bytes EVMInstructionInterpreter::readMemory(u256 const& _offset, u256 const& _size)
-{
-	yulAssert(_size <= 0xffff, "Too large read.");
-	bytes data(size_t(_size), uint8_t(0));
-	for (size_t i = 0; i < data.size(); ++i)
-		data[i] = m_state.memory[_offset + i];
-	return data;
-}
-
 u256 EVMInstructionInterpreter::readMemoryWord(u256 const& _offset)
 {
-	return u256(h256(readMemory(_offset, 32)));
+	return u256(h256(m_state.readMemory(_offset, 32)));
 }
 
 void EVMInstructionInterpreter::writeMemoryWord(u256 const& _offset, u256 const& _value)

test/tools/yulInterpreter/EVMInstructionInterpreter.h

@@ -42,6 +42,14 @@ struct BuiltinFunctionForEVM;
 namespace solidity::yul::test
 {
 
+/// Copy @a _size bytes of @a _source at offset @a _sourceOffset to
+/// @a _target at offset @a _targetOffset. Behaves as if @a _source would
+/// continue with an infinite sequence of zero bytes beyond its end.
+void copyZeroExtended(
+	std::map<u256, uint8_t>& _target, bytes const& _source,
+	size_t _targetOffset, size_t _sourceOffset, size_t _size
+);
+
 struct InterpreterState;
 
 /**

test/tools/yulInterpreter/Inspector.cpp

@@ -0,0 +1,156 @@
+/*
+	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
+/**
+ * Yul interpreter.
+ */
+
+#include <test/tools/yulInterpreter/Inspector.h>
+
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string.hpp>
+
+using namespace solidity;
+using namespace solidity::yul;
+using namespace solidity::yul::test;
+
+using namespace std;
+
+namespace
+{
+
+void printVariable(YulString const& _name, u256 const& _value)
+{
+	cout << "\t" << _name.str() << " = " << _value.str();
+
+	if (_value != 0)
+		cout << " (" << toCompactHexWithPrefix(_value) << ")";
+
+	cout << endl;
+}
+
+}
+
+void InspectedInterpreter::run(
+	std::shared_ptr<Inspector> _inspector,
+	InterpreterState& _state,
+	Dialect const& _dialect,
+	Block const& _ast,
+	bool _disableExternalCalls,
+	bool _disableMemoryTrace
+)
+{
+	Scope scope;
+	InspectedInterpreter{_inspector, _state, _dialect, scope, _disableExternalCalls, _disableMemoryTrace}(_ast);
+}
+
+Inspector::NodeAction Inspector::queryUser(DebugData const& _data, map<YulString, u256> const& _variables)
+{
+	if (m_stepMode == NodeAction::RunNode)
+	{
+		// Output instructions that are being skipped/run
+		cout << "Running " << currentSource(_data) << endl;
+
+		return NodeAction::StepThroughNode;
+	}
+
+	string input;
+
+	while (true)
+	{
+		// Output sourcecode about to run.
+		cout << "> " << currentSource(_data) << endl;
+
+		// Ask user for action
+		cout << endl
+			<< "(s)tep/(n)ext/(i)nspect/(p)rint/all (v)ariables?"
+			<< endl
+			<< "# ";
+
+		cout.flush();
+
+		getline(cin, input);
+		boost::algorithm::trim(input);
+
+		// Imitate GDB and repeat last cmd for empty string input.
+		if (input == "")
+			input = m_lastInput;
+		else
+			m_lastInput = input;
+
+		if (input == "next" || input == "n")
+			return NodeAction::RunNode;
+		else if (input == "step" || input == "s")
+			return NodeAction::StepThroughNode;
+		else if (input == "inspect" || input == "i")
+			m_state.dumpTraceAndState(cout, false);
+		else if (input == "variables" || input == "v")
+		{
+			for (auto &&[yulStr, val]: _variables)
+				printVariable(yulStr, val);
+			cout << endl;
+		}
+		else if (
+			boost::starts_with(input, "print") ||
+			boost::starts_with(input, "p")
+		)
+		{
+			size_t whitespacePos = input.find(' ');
+
+			if (whitespacePos == string::npos)
+				cout << "Error parsing command! Expected variable name." << endl;
+
+			string const varname = input.substr(whitespacePos + 1);
+
+			vector<string> candidates;
+
+			bool found = false;
+			for (auto &&[yulStr, val]: _variables)
+				if (yulStr.str() == varname)
+				{
+					printVariable(yulStr, val);
+					found = true;
+					break;
+				}
+
+			if (!found)
+				cout << varname << " not found." << endl;
+		}
+	}
+}
+
+std::string Inspector::currentSource(DebugData const& _data) const
+{
+	return m_source.substr(
+		static_cast<size_t>(_data.nativeLocation.start),
+		static_cast<size_t>(_data.nativeLocation.end - _data.nativeLocation.start)
+	);
+}
+
+u256 InspectedInterpreter::evaluate(Expression const& _expression)
+{
+	InspectedExpressionEvaluator ev(m_inspector, m_state, m_dialect, *m_scope, m_variables, m_disableExternalCalls, m_disableMemoryTrace);
+	ev.visit(_expression);
+	return ev.value();
+}
+
+std::vector<u256> InspectedInterpreter::evaluateMulti(Expression const& _expression)
+{
+	InspectedExpressionEvaluator ev(m_inspector, m_state, m_dialect, *m_scope, m_variables, m_disableExternalCalls, m_disableMemoryTrace);
+	ev.visit(_expression);
+	return ev.values();
+}

test/tools/yulInterpreter/Inspector.h

@@ -0,0 +1,213 @@
+/*
+	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
+/**
+ * Yul inspector.
+ */
+
+#include <test/tools/yulInterpreter/Interpreter.h>
+
+#include <libyul/AST.h>
+
+#include <string>
+
+#pragma once
+
+namespace solidity::yul::test
+{
+
+/**
+ * Inspector class to respond to queries by the user for:
+ *
+ * * Stepping through and over instructions.
+ * * Printing a specific or all variables.
+ * * Inspecting memory, storage and calldata memory.
+ */
+class Inspector
+{
+public:
+	enum class NodeAction
+	{
+		RunNode,
+		StepThroughNode,
+	};
+
+	Inspector(std::string const& _source, InterpreterState const& _state)
+		:m_source(_source), m_state(_state) {}
+
+	/* Asks the user what action to take.
+	 * @returns NodeAction::RunNode if the current AST node (and all children nodes!) should be
+	 *          processed without stopping, else NodeAction::StepThroughNode.
+	 */
+	NodeAction queryUser(DebugData const& _data, std::map<YulString, u256> const& _variables);
+
+	void stepMode(NodeAction _action) { m_stepMode = _action; }
+
+	std::string const& source() const { return m_source; }
+
+	void interactiveVisit(DebugData const& _debugData, std::map<YulString, u256> const& _variables, std::function<void()> _visitNode)
+	{
+		Inspector::NodeAction action = queryUser(_debugData, _variables);
+
+		if (action == NodeAction::RunNode)
+		{
+			// user requested to run the whole node without stopping
+			stepMode(Inspector::NodeAction::RunNode);
+
+			_visitNode();
+
+			// Reset step mode back
+			stepMode(Inspector::NodeAction::StepThroughNode);
+		}
+		else
+			_visitNode();
+	}
+
+private:
+	std::string currentSource(DebugData const& _data) const;
+
+	/// Source of the file
+	std::string const& m_source;
+
+	/// State of the interpreter
+	InterpreterState const& m_state;
+
+	/// Last user query command
+	std::string m_lastInput;
+
+	/// Used to run AST nodes without user interaction
+	NodeAction m_stepMode = NodeAction::StepThroughNode;
+};
+
+/**
+ * Yul Interpreter with inspection. Allows the user to go through the code step
+ * by step and inspect the state using the `Inspector` class
+ */
+class InspectedInterpreter: public Interpreter
+{
+public:
+	static void run(
+		std::shared_ptr<Inspector> _inspector,
+		InterpreterState& _state,
+		Dialect const& _dialect,
+		Block const& _ast,
+		bool _disableExternalCalls,
+		bool _disableMemoryTracing
+	);
+
+	InspectedInterpreter(
+		std::shared_ptr<Inspector> _inspector,
+		InterpreterState& _state,
+		Dialect const& _dialect,
+		Scope& _scope,
+		bool _disableExternalCalls,
+		bool _disableMemoryTracing,
+		std::map<YulString, u256> _variables = {}
+	):
+		Interpreter(_state, _dialect, _scope, _disableExternalCalls, _disableMemoryTracing, _variables),
+		m_inspector(_inspector)
+	{
+	}
+
+	void operator()(ExpressionStatement const& _node) override { helper(_node); }
+	void operator()(Assignment const& _node) override { helper(_node); }
+	void operator()(VariableDeclaration const& _node) override { helper(_node); }
+	void operator()(If const& _node) override { helper(_node); }
+	void operator()(Switch const& _node) override { helper(_node); }
+	void operator()(ForLoop const& _node) override { helper(_node); }
+	void operator()(Break const& _node) override { helper(_node); }
+	void operator()(Continue const& _node) override { helper(_node); }
+	void operator()(Leave const& _node) override { helper(_node); }
+	void operator()(Block const& _node) override { helper(_node); }
+protected:
+	/// Asserts that the expression evaluates to exactly one value and returns it.
+	u256 evaluate(Expression const& _expression) override;
+	/// Evaluates the expression and returns its value.
+	std::vector<u256> evaluateMulti(Expression const& _expression) override;
+private:
+	std::shared_ptr<Inspector> m_inspector;
+
+	template <typename ConcreteNode>
+	void helper(ConcreteNode const& _node)
+	{
+		m_inspector->interactiveVisit(*_node.debugData, m_variables, [&]() {
+			Interpreter::operator()(_node);
+		});
+	}
+
+};
+
+
+class InspectedExpressionEvaluator: public ExpressionEvaluator
+{
+public:
+	InspectedExpressionEvaluator(
+		std::shared_ptr<Inspector> _inspector,
+		InterpreterState& _state,
+		Dialect const& _dialect,
+		Scope& _scope,
+		std::map<YulString, u256> const& _variables,
+		bool _disableExternalCalls,
+		bool _disableMemoryTrace
+	):
+		ExpressionEvaluator(_state, _dialect, _scope, _variables, _disableExternalCalls, _disableMemoryTrace),
+		m_inspector(_inspector)
+	{}
+
+	template <typename ConcreteNode>
+	void helper(ConcreteNode const& _node)
+	{
+		m_inspector->interactiveVisit(*_node.debugData, m_variables, [&]() {
+			ExpressionEvaluator::operator()(_node);
+		});
+	}
+
+	void operator()(Literal const& _node) override { helper(_node); }
+	void operator()(Identifier const& _node) override { helper(_node); }
+	void operator()(FunctionCall const& _node) override { helper(_node); }
+protected:
+	std::unique_ptr<Interpreter> makeInterpreterCopy(std::map<YulString, u256> _variables = {}) const override
+	{
+		return std::make_unique<InspectedInterpreter>(
+			m_inspector,
+			m_state,
+			m_dialect,
+			m_scope,
+			m_disableExternalCalls,
+			m_disableMemoryTrace,
+			std::move(_variables)
+		);
+	}
+	std::unique_ptr<Interpreter> makeInterpreterNew(InterpreterState& _state, Scope& _scope) const override
+	{
+		return std::make_unique<InspectedInterpreter>(
+			std::make_unique<Inspector>(
+				m_inspector->source(),
+				_state
+			),
+			_state,
+			m_dialect,
+			_scope,
+			m_disableExternalCalls,
+			m_disableMemoryTrace
+		);
+	}
+private:
+	std::shared_ptr<Inspector> m_inspector;
+};
+
+}

test/tools/yulInterpreter/Interpreter.cpp

@@ -70,17 +70,46 @@ void InterpreterState::dumpTraceAndState(ostream& _out, bool _disableMemoryTrace
 	}
 	_out << "Storage dump:" << endl;
 	dumpStorage(_out);
+
+	if (!calldata.empty())
+	{
+		_out << "Calldata dump:";
+
+		for (size_t offset = 0; offset < calldata.size(); ++offset)
+			if (calldata[offset] != 0)
+			{
+				if (offset % 32 == 0)
+					_out <<
+						std::endl <<
+						"  " <<
+						std::uppercase <<
+						std::hex <<
+						std::setfill(' ') <<
+						std::setw(4) <<
+						offset <<
+						": ";
+
+				_out <<
+					std::hex <<
+					std::setw(2) <<
+					std::setfill('0') <<
+					static_cast<int>(calldata[offset]);
+			}
+
+		_out << endl;
+	}
 }
 
 void Interpreter::run(
 	InterpreterState& _state,
 	Dialect const& _dialect,
 	Block const& _ast,
+	bool _disableExternalCalls,
 	bool _disableMemoryTrace
 )
 {
 	Scope scope;
-	Interpreter{_state, _dialect, scope, _disableMemoryTrace}(_ast);
+	Interpreter{_state, _dialect, scope, _disableExternalCalls, _disableMemoryTrace}(_ast);
 }
 
 void Interpreter::operator()(ExpressionStatement const& _expressionStatement)
@@ -215,14 +244,14 @@ void Interpreter::operator()(Block const& _block)
 
 u256 Interpreter::evaluate(Expression const& _expression)
 {
-	ExpressionEvaluator ev(m_state, m_dialect, *m_scope, m_variables, m_disableMemoryTrace);
+	ExpressionEvaluator ev(m_state, m_dialect, *m_scope, m_variables, m_disableExternalCalls, m_disableMemoryTrace);
 	ev.visit(_expression);
 	return ev.value();
 }
 
 vector<u256> Interpreter::evaluateMulti(Expression const& _expression)
 {
-	ExpressionEvaluator ev(m_state, m_dialect, *m_scope, m_variables, m_disableMemoryTrace);
+	ExpressionEvaluator ev(m_state, m_dialect, *m_scope, m_variables, m_disableExternalCalls, m_disableMemoryTrace);
 	ev.visit(_expression);
 	return ev.values();
 }
@@ -286,7 +315,17 @@ void ExpressionEvaluator::operator()(FunctionCall const& _funCall)
 		if (BuiltinFunctionForEVM const* fun = dialect->builtin(_funCall.functionName.name))
 		{
 			EVMInstructionInterpreter interpreter(m_state, m_disableMemoryTrace);
-			setValue(interpreter.evalBuiltin(*fun, _funCall.arguments, values()));
+
+			u256 const value = interpreter.evalBuiltin(*fun, _funCall.arguments, values());
+
+			if (
+				!m_disableExternalCalls &&
+				fun->instruction &&
+				evmasm::isCallInstruction(*fun->instruction)
+			)
+				runExternalCall(*fun->instruction);
+
+			setValue(value);
 			return;
 		}
 	}
@@ -314,13 +353,13 @@ void ExpressionEvaluator::operator()(FunctionCall const& _funCall)
 		variables[fun->returnVariables.at(i).name] = 0;
 
 	m_state.controlFlowState = ControlFlowState::Default;
-	Interpreter interpreter(m_state, m_dialect, *scope, m_disableMemoryTrace, std::move(variables));
+	unique_ptr<Interpreter> interpreter = makeInterpreterCopy(std::move(variables));
-	interpreter(fun->body);
+	(*interpreter)(fun->body);
 	m_state.controlFlowState = ControlFlowState::Default;
 
 	m_values.clear();
 	for (auto const& retVar: fun->returnVariables)
-		m_values.emplace_back(interpreter.valueOfVariable(retVar.name));
+		m_values.emplace_back(interpreter->valueOfVariable(retVar.name));
 }
 
 u256 ExpressionEvaluator::value() const
@@ -349,7 +388,19 @@ void ExpressionEvaluator::evaluateArgs(
 		if (!_literalArguments || !_literalArguments->at(_expr.size() - i - 1))
 			visit(expr);
 		else
-			m_values = {0};
+		{
+			string literal = std::get<Literal>(expr).value.str();
+
+			try
+			{
+				m_values = {u256(literal)};
+			}
+			catch (exception&)
+			{
+				m_values = {u256(0)};
+			}
+		}
+
 		values.push_back(value());
 		++i;
 	}
@@ -366,3 +417,90 @@ void ExpressionEvaluator::incrementStep()
 		BOOST_THROW_EXCEPTION(ExpressionNestingLimitReached());
 	}
 }
+
+void ExpressionEvaluator::runExternalCall(evmasm::Instruction _instruction)
+{
+	u256 memOutOffset = 0;
+	u256 memOutSize = 0;
+	u256 callvalue = 0;
+	u256 memInOffset = 0;
+	u256 memInSize = 0;
+
+	// Setup memOut* values
+	if (
+		_instruction == evmasm::Instruction::CALL ||
+		_instruction == evmasm::Instruction::CALLCODE
+	)
+	{
+		memOutOffset = values()[5];
+		memOutSize = values()[6];
+		callvalue = values()[2];
+		memInOffset = values()[3];
+		memInSize = values()[4];
+	}
+	else if (
+		_instruction == evmasm::Instruction::DELEGATECALL ||
+		_instruction == evmasm::Instruction::STATICCALL
+	)
+	{
+		memOutOffset = values()[4];
+		memOutSize = values()[5];
+		memInOffset = values()[2];
+		memInSize = values()[3];
+	}
+	else
+		yulAssert(false);
+
+	// Don't execute external call if it isn't our own address
+	if (values()[1] != util::h160::Arith(m_state.address))
+		return;
+
+	Scope tmpScope;
+	InterpreterState tmpState;
+	tmpState.calldata = m_state.readMemory(memInOffset, memInSize);
+	tmpState.callvalue = callvalue;
+	tmpState.numInstance = m_state.numInstance + 1;
+
+	yulAssert(tmpState.numInstance < 1024, "Detected more than 1024 recursive calls, aborting...");
+
+	// Create new interpreter for the called contract
+	unique_ptr<Interpreter> newInterpreter = makeInterpreterNew(tmpState, tmpScope);
+
+	Scope* abstractRootScope = &m_scope;
+	Scope* fileScope = nullptr;
+	Block const* ast = nullptr;
+
+	// Find file scope
+	while (abstractRootScope->parent)
+	{
+		fileScope = abstractRootScope;
+		abstractRootScope = abstractRootScope->parent;
+	}
+
+	// Get AST for file scope
+	for (auto&& [block, scope]: abstractRootScope->subScopes)
+		if (scope.get() == fileScope)
+		{
+			ast = block;
+			break;
+		}
+
+	yulAssert(ast);
+
+	try
+	{
+		(*newInterpreter)(*ast);
+	}
+	catch (ExplicitlyTerminatedWithReturn const&)
+	{
+		// Copy return data to our memory
+		copyZeroExtended(
+			m_state.memory,
+			newInterpreter->returnData(),
+			memOutOffset.convert_to<size_t>(),
+			0,
+			memOutSize.convert_to<size_t>()
+		);
+		m_state.returndata = newInterpreter->returnData();
+	}
+}

test/tools/yulInterpreter/Interpreter.h

@@ -24,6 +24,8 @@
 #include <libyul/ASTForward.h>
 #include <libyul/optimiser/ASTWalker.h>
 
+#include <libevmasm/Instruction.h>
+
 #include <libsolutil/FixedHash.h>
 #include <libsolutil/CommonData.h>
 
@@ -47,6 +49,10 @@ class ExplicitlyTerminated: public InterpreterTerminatedGeneric
 {
 };
 
+class ExplicitlyTerminatedWithReturn: public ExplicitlyTerminated
+{
+};
+
 class StepLimitReached: public InterpreterTerminatedGeneric
 {
 };
@@ -101,6 +107,9 @@ struct InterpreterState
 	size_t maxExprNesting = 0;
 	ControlFlowState controlFlowState = ControlFlowState::Default;
 
+	/// Number of the current state instance, used for recursion protection
+	size_t numInstance = 0;
+
 	/// Prints execution trace and non-zero storage to @param _out.
 	/// Flag @param _disableMemoryTrace, if set, does not produce a memory dump. This
 	/// avoids false positives reports by the fuzzer when certain optimizer steps are
@@ -108,6 +117,15 @@ struct InterpreterState
 	void dumpTraceAndState(std::ostream& _out, bool _disableMemoryTrace) const;
 	/// Prints non-zero storage to @param _out.
 	void dumpStorage(std::ostream& _out) const;
+
+	bytes readMemory(u256 const& _offset, u256 const& _size)
+	{
+		yulAssert(_size <= 0xffff, "Too large read.");
+		bytes data(size_t(_size), uint8_t(0));
+		for (size_t i = 0; i < data.size(); ++i)
+			data[i] = memory[_offset + i];
+		return data;
+	}
 };
 
 /**
@@ -135,6 +153,7 @@ public:
 		InterpreterState& _state,
 		Dialect const& _dialect,
 		Block const& _ast,
+		bool _disableExternalCalls,
 		bool _disableMemoryTracing
 	);
 
@@ -142,6 +161,7 @@ public:
 		InterpreterState& _state,
 		Dialect const& _dialect,
 		Scope& _scope,
+		bool _disableExternalCalls,
 		bool _disableMemoryTracing,
 		std::map<YulString, u256> _variables = {}
 	):
@@ -149,6 +169,7 @@ public:
 		m_state(_state),
 		m_variables(std::move(_variables)),
 		m_scope(&_scope),
+		m_disableExternalCalls(_disableExternalCalls),
 		m_disableMemoryTrace(_disableMemoryTracing)
 	{
 	}
@@ -165,15 +186,16 @@ public:
 	void operator()(Leave const&) override;
 	void operator()(Block const& _block) override;
 
+	bytes returnData() const { return m_state.returndata; }
 	std::vector<std::string> const& trace() const { return m_state.trace; }
 
 	u256 valueOfVariable(YulString _name) const { return m_variables.at(_name); }
 
-private:
+protected:
 	/// Asserts that the expression evaluates to exactly one value and returns it.
-	u256 evaluate(Expression const& _expression);
+	virtual u256 evaluate(Expression const& _expression);
 	/// Evaluates the expression and returns its value.
-	std::vector<u256> evaluateMulti(Expression const& _expression);
+	virtual std::vector<u256> evaluateMulti(Expression const& _expression);
 
 	void enterScope(Block const& _block);
 	void leaveScope();
@@ -187,6 +209,9 @@ private:
 	/// Values of variables.
 	std::map<YulString, u256> m_variables;
 	Scope* m_scope;
+	/// If not set, external calls (e.g. using `call()`) to the same contract
+	/// are evaluated in a new parser instance.
+	bool m_disableExternalCalls;
 	bool m_disableMemoryTrace;
 };
 
@@ -201,12 +226,14 @@ public:
 		Dialect const& _dialect,
 		Scope& _scope,
 		std::map<YulString, u256> const& _variables,
+		bool _disableExternalCalls,
 		bool _disableMemoryTrace
 	):
 		m_state(_state),
 		m_dialect(_dialect),
 		m_variables(_variables),
 		m_scope(_scope),
+		m_disableExternalCalls(_disableExternalCalls),
 		m_disableMemoryTrace(_disableMemoryTrace)
 	{}
 
@@ -219,7 +246,30 @@ public:
 	/// Returns the list of values of the expression.
 	std::vector<u256> values() const { return m_values; }
 
-private:
+protected:
+	void runExternalCall(evmasm::Instruction _instruction);
+	virtual std::unique_ptr<Interpreter> makeInterpreterCopy(std::map<YulString, u256> _variables = {}) const
+	{
+		return std::make_unique<Interpreter>(
+			m_state,
+			m_dialect,
+			m_scope,
+			m_disableExternalCalls,
+			m_disableMemoryTrace,
+			std::move(_variables)
+		);
+	}
+	virtual std::unique_ptr<Interpreter> makeInterpreterNew(InterpreterState& _state, Scope& _scope) const
+	{
+		return std::make_unique<Interpreter>(
+			_state,
+			m_dialect,
+			_scope,
+			m_disableExternalCalls,
+			m_disableMemoryTrace
+		);
+	}
+
 	void setValue(u256 _value);
 
 	/// Evaluates the given expression from right to left and
@@ -243,6 +293,7 @@ private:
 	std::vector<u256> m_values;
 	/// Current expression nesting level
 	unsigned m_nestingLevel = 0;
+	bool m_disableExternalCalls;
 	/// Flag to disable memory tracing
 	bool m_disableMemoryTrace;
 };

test/tools/yulrun.cpp

@@ -20,6 +20,7 @@
  */
 
 #include <test/tools/yulInterpreter/Interpreter.h>
+#include <test/tools/yulInterpreter/Inspector.h>
 
 #include <libyul/AsmAnalysisInfo.h>
 #include <libyul/AsmAnalysis.h>
@@ -74,7 +75,7 @@ pair<shared_ptr<Block>, shared_ptr<AsmAnalysisInfo>> parse(string const& _source
 	}
 }
 
-void interpret(string const& _source)
+void interpret(string const& _source, bool _inspect, bool _disableExternalCalls)
 {
 	shared_ptr<Block> ast;
 	shared_ptr<AsmAnalysisInfo> analysisInfo;
@@ -87,7 +88,12 @@ void interpret(string const& _source)
 	try
 	{
 		Dialect const& dialect(EVMDialect::strictAssemblyForEVMObjects(langutil::EVMVersion{}));
-		Interpreter::run(state, dialect, *ast, /*disableMemoryTracing=*/false);
+
+		if (_inspect)
+			InspectedInterpreter::run(std::make_shared<Inspector>(_source, state), state, dialect, *ast, _disableExternalCalls, /*disableMemoryTracing=*/false);
+
+		else
+			Interpreter::run(state, dialect, *ast, _disableExternalCalls, /*disableMemoryTracing=*/false);
 	}
 	catch (InterpreterTerminatedGeneric const&)
 	{
@@ -110,6 +116,8 @@ Allowed options)",
 		po::options_description::m_default_line_length - 23);
 	options.add_options()
 		("help", "Show this help screen.")
+		("enable-external-calls", "Enable external calls")
+		("interactive", "Run interactive")
 		("input-file", po::value<vector<string>>(), "input file");
 	po::positional_options_description filesPositions;
 	filesPositions.add("input-file", -1);
@@ -153,7 +161,7 @@ Allowed options)",
 		else
 			input = readUntilEnd(cin);
 
-		interpret(input);
+		interpret(input, arguments.count("interactive"), !arguments.count("enable-external-calls"));
 	}
 
 	return 0;