Change VM interface to return a copy of output.

evmjit/libevmjit-cpp/JitVM.cpp

@@ -18,7 +18,7 @@ namespace eth
 
 extern "C" void env_sload(); // fake declaration for linker symbol stripping workaround, see a call below
 
-bytesConstRef JitVM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _step)
+bytesConstRef JitVM::execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _step)
 {
 	using namespace jit;
 
@@ -33,7 +33,7 @@ bytesConstRef JitVM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, ui
 	{
 		cwarn << "Execution rejected by EVM JIT (gas limit: " << io_gas << "), executing with interpreter";
 		m_fallbackVM = VMFactory::create(VMKind::Interpreter);
-		return m_fallbackVM->go(io_gas, _ext, _onOp, _step);
+		return m_fallbackVM->execImpl(io_gas, _ext, _onOp, _step);
 	}
 
 	m_data.gas 			= static_cast<decltype(m_data.gas)>(io_gas);

evmjit/libevmjit-cpp/JitVM.h

@@ -11,7 +11,7 @@ namespace eth
 class JitVM: public VMFace
 {
 public:
-	virtual bytesConstRef go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
+	virtual bytesConstRef execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
 
 private:
 	jit::RuntimeData m_data;

libethereum/Executive.cpp

@@ -46,7 +46,7 @@ u256 Executive::gasUsed() const
 
 ExecutionResult Executive::executionResult() const
 {
-	return ExecutionResult(gasUsed(), m_excepted, m_newAddress, m_out, m_codeDeposit, m_ext ? m_ext->sub.refunds : 0, m_depositSize, m_gasForDeposit);
+	return ExecutionResult(gasUsed(), m_excepted, m_newAddress, out(), m_codeDeposit, m_ext ? m_ext->sub.refunds : 0, m_depositSize, m_gasForDeposit);
 }
 
 void Executive::accrueSubState(SubState& _parentContext)
@@ -145,8 +145,7 @@ bool Executive::call(CallParameters const& _p, u256 const& _gasPrice, Address co
 		else
 		{
 			m_gas = (u256)(_p.gas - g);
-			m_precompiledOut = it->second.exec(_p.data);
-			m_out = &m_precompiledOut;
+			m_out = it->second.exec(_p.data);
 		}
 	}
 	else
@@ -219,7 +218,7 @@ bool Executive::go(OnOpFunc const& _onOp)
 #endif
 		try
 		{
-			m_out = m_vm->go(m_gas, *m_ext, _onOp);
+			m_out = m_vm->exec(m_gas, *m_ext, _onOp);
 
 			if (m_isCreation)
 			{
@@ -232,11 +231,10 @@ bool Executive::go(OnOpFunc const& _onOp)
 				}
 				else
 				{
-
 					m_codeDeposit = CodeDeposit::Failed;
-					m_out.reset();
+					m_out.clear();
 				}
-				m_s.m_cache[m_newAddress].setCode(m_out.toBytes());
+				m_s.m_cache[m_newAddress].setCode(std::move(m_out));
 			}
 		}
 		catch (StepsDone const&)

libethereum/Executive.h

@@ -109,7 +109,7 @@ public:
 	/// @returns gas remaining after the transaction/operation. Valid after the transaction has been executed.
 	u256 gas() const { return m_gas; }
 	/// @returns output data of the transaction/operation.
-	bytesConstRef out() const { return m_out; }
+	bytesConstRef out() const { return {m_out.data(), m_out.size()}; }
 	/// @returns the new address for the created contract in the CREATE operation.
 	h160 newAddress() const { return m_newAddress; }
 	/// @returns true iff the operation ended with a VM exception.
@@ -123,8 +123,7 @@ private:
 	LastHashes m_lastHashes;
 	std::shared_ptr<ExtVM> m_ext;		///< The VM externality object for the VM execution or null if no VM is required.
 	std::unique_ptr<VMFace> m_vm;		///< The VM object or null if no VM is required.
-	bytes m_precompiledOut;				///< Used for the output when there is no VM for a contract (i.e. precompiled).
-	bytesConstRef m_out;				///< The copyable output.
+	bytes m_out;						///< The VM execution output.
 	Address m_newAddress;				///< The address of the created contract in the case of create() being called.
 
 	unsigned m_depth = 0;				///< The context's call-depth.

libevm/SmartVM.cpp

@@ -41,7 +41,7 @@ namespace
 	}
 }
 
-bytesConstRef SmartVM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _steps)
+bytesConstRef SmartVM::execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _steps)
 {
 	auto codeHash = sha3(_ext.code);
 	auto vmKind = VMKind::Interpreter; // default VM
@@ -68,7 +68,7 @@ bytesConstRef SmartVM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp,
 	// TODO: Selected VM must be kept only because it returns reference to its internal memory.
 	//       VM implementations should be stateless, without escaping memory reference.
 	m_selectedVM = VMFactory::create(vmKind);
-	return m_selectedVM->go(io_gas, _ext, _onOp, _steps);
+	return m_selectedVM->execImpl(io_gas, _ext, _onOp, _steps);
 }
 
 }

libevm/SmartVM.h

@@ -31,7 +31,7 @@ namespace eth
 class SmartVM: public VMFace
 {
 public:
-	virtual bytesConstRef go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
+	virtual bytesConstRef execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
 
 private:
 	std::unique_ptr<VMFace> m_selectedVM;

libevm/VM.cpp

@@ -45,7 +45,7 @@ static array<InstructionMetric, 256> metrics()
 	return s_ret;
 }
 
-bytesConstRef VM::go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _steps)
+bytesConstRef VM::execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp, uint64_t _steps)
 {
 	// Reset leftovers from possible previous run
 	m_curPC = 0;

libevm/VM.h

@@ -52,7 +52,7 @@ inline u256 fromAddress(Address _a)
 class VM: public VMFace
 {
 public:
-	virtual bytesConstRef go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
+	virtual bytesConstRef execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) override final;
 
 	u256 curPC() const { return m_curPC; }
 

libevm/VMFace.h

@@ -43,7 +43,12 @@ public:
 	VMFace(VMFace const&) = delete;
 	VMFace& operator=(VMFace const&) = delete;
 
-	virtual bytesConstRef go(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) = 0;
+	bytes exec(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1)
+	{
+		return execImpl(io_gas, _ext, _onOp, _steps).toVector();
+	}
+
+	virtual bytesConstRef execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _onOp = {}, uint64_t _steps = (uint64_t)-1) = 0;
 };
 
 }

test/fuzzTesting/checkRandomVMTest.cpp

@@ -98,9 +98,9 @@ bool doVMTest(mValue& _v)
 		try
 		{
 			auto vm = eth::VMFactory::create();
-			output = vm->go(fev.gas, fev, fev.simpleTrace()).toBytes();
+			output = vm->exec(fev.gas, fev, fev.simpleTrace());
 		}
-		catch (eth::VMException)
+		catch (eth::VMException const&)
 		{
 			cnote << "Safe VM Exception";
 			vmExceptionOccured = true;

test/fuzzTesting/createRandomVMTest.cpp

@@ -160,7 +160,7 @@ void doMyTests(json_spirit::mValue& _v)
 		bool vmExceptionOccured = false;
 		try
 		{
-			output = vm->go(fev.gas, fev, fev.simpleTrace()).toBytes();
+			output = vm->exec(fev.gas, fev, fev.simpleTrace());
 		}
 		catch (eth::VMException const& _e)
 		{

test/libevm/vm.cpp

@@ -329,12 +329,10 @@ void doVMTests(json_spirit::mValue& v, bool _fillin)
 		{
 			auto vm = eth::VMFactory::create();
 			auto vmtrace = Options::get().vmtrace ? fev.simpleTrace() : OnOpFunc{};
-			auto outputRef = bytesConstRef{};
 			{
 				Listener::ExecTimeGuard guard{i.first};
-				outputRef = vm->go(fev.gas, fev, vmtrace);
+				output = vm->exec(fev.gas, fev, vmtrace);
 			}
-			output = outputRef.toBytes();
 		}
 		catch (VMException const&)
 		{