pwasm-std update (#7018)

Cargo.lock

@@ -2387,7 +2387,7 @@ dependencies = [
 
 [[package]]
 name = "parity-wasm"
-version = "0.15.1"
+version = "0.15.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "byteorder 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3575,7 +3575,7 @@ dependencies = [
  "ethcore-logger 1.8.0",
  "ethcore-util 1.8.3",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-wasm 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-wasm 0.15.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "vm 0.1.0",
  "wasm-utils 0.1.0 (git+https://github.com/paritytech/wasm-utils)",
 ]
@@ -3591,7 +3591,7 @@ dependencies = [
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-wasm 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-wasm 0.15.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -3815,7 +3815,7 @@ dependencies = [
 "checksum parity-dapps-glue 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ddaeb8543c6823e93dae65a25eb8083ebfeee8f0000031119d7a0055b2e8fc63"
 "checksum parity-tokio-ipc 0.1.5 (git+https://github.com/nikvolf/parity-tokio-ipc)" = "<none>"
 "checksum parity-ui-precompiled 1.4.0 (git+https://github.com/paritytech/js-precompiled.git?branch=beta)" = "<none>"
-"checksum parity-wasm 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)" = "95f6243c2d6fadf903b5edfd0011817efc20522ce5f360abf4648c24ea87581a"
+"checksum parity-wasm 0.15.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8431a184ad88cfbcd71a792aaca319cc7203a94300c26b8dce2d0df0681ea87d"
 "checksum parity-wordlist 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "81451bfab101d186f8fc4a0aa13cb5539b31b02c4ed96425a0842e2a413daba6"
 "checksum parking_lot 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "149d8f5b97f3c1133e3cfcd8886449959e856b557ff281e292b733d7c69e005e"
 "checksum parking_lot_core 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "4f610cb9664da38e417ea3225f23051f589851999535290e077939838ab7a595"

ethcore/res/wasm-tests

@@ -1 +1 @@
-Subproject commit 94b7877b5826a53627b8732ea0feb45869dd04ab
+Subproject commit 9a1fcbf0d4e73bea437577e807bc38c7ba243d80

ethcore/vm/src/schedule.rs

@@ -127,12 +127,14 @@ pub struct WasmCosts {
 	pub mul: u32,
 	/// Memory (load/store) operations multiplier.
 	pub mem: u32,
-	/// Memory copy operation.
+	/// Memory copy operation, per byte.
 	pub mem_copy: u32,
+	/// Memory move operation, per byte.
+	pub mem_move: u32,
+	/// Memory set operation, per byte.
+	pub mem_set: u32,
 	/// Static region charge, per byte.
 	pub static_region: u32,
-	/// General static query of u64 value from env-info
-	pub static_u64: u32,
 	/// General static query of U256 value from env-info
 	pub static_u256: u32,
 	/// General static query of Address value from env-info
@@ -147,11 +149,9 @@ impl Default for WasmCosts {
 			mul: 4,
 			mem: 2,
 			mem_copy: 1,
+			mem_move: 1,
+			mem_set: 1,
 			static_region: 1,
-
-			// due to runtime issues, this can be slow
-			static_u64: 32,
-
 			static_u256: 64,
 			static_address: 40,
 		}

ethcore/wasm/src/env.rs

@@ -38,12 +38,12 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 		None,
 	),
 	Static(
-		"_malloc",
+		"_ext_malloc",
 		&[I32],
 		Some(I32),
 	),
 	Static(
-		"_free",
+		"_ext_free",
 		&[I32],
 		None,
 	),
@@ -92,6 +92,21 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 		&[I32; 3],
 		Some(I32),
 	),
+	Static(
+		"_ext_memcpy",
+		&[I32; 3],
+		Some(I32),
+	),
+	Static(
+		"_ext_memset",
+		&[I32; 3],
+		Some(I32),
+	),
+	Static(
+		"_ext_memmove",
+		&[I32; 3],
+		Some(I32),
+	),
 	Static(
 		"_panic",
 		&[I32; 2],
@@ -99,7 +114,7 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 	),
 	Static(
 		"_blockhash",
-		&[I32; 3],
+		&[I64, I32],
 		Some(I32),
 	),
 	Static(
@@ -130,12 +145,12 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 	Static(
 		"_timestamp",
 		&[],
-		Some(I32),
+		Some(I64),
 	),
 	Static(
 		"_blocknumber",
 		&[],
-		Some(I32),
+		Some(I64),
 	),
 	Static(
 		"_difficulty",
@@ -162,8 +177,8 @@ pub const SIGNATURES: &'static [UserFunctionDescriptor] = &[
 
 	Static(
 		"_llvm_bswap_i64",
-		&[I32; 2],
+		&[I64],
-		Some(I32)
+		Some(I64)
 	),
 ];
 

ethcore/wasm/src/runtime.rs

@@ -560,32 +560,67 @@ impl<'a, 'b> Runtime<'a, 'b> {
 	fn mem_copy(&mut self, context: InterpreterCallerContext)
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
+		//
+		// method signature:
+		//   fn memcpy(dest: *const u8, src: *const u8, len: u32) -> *mut u8;
+		//
+
 		let len = context.value_stack.pop_as::<i32>()? as u32;
-		let dst = context.value_stack.pop_as::<i32>()? as u32;
 		let src = context.value_stack.pop_as::<i32>()? as u32;
+		let dst = context.value_stack.pop_as::<i32>()? as u32;
 
 		self.charge(|schedule| schedule.wasm.mem_copy as u64 * len as u64)?;
 
-		let mem = self.memory().get(src, len as usize)?;
+		self.memory().copy_nonoverlapping(src as usize, dst as usize, len as usize)?;
-		self.memory().set(dst, &mem)?;
 
-		Ok(Some(0i32.into()))
+		Ok(Some(Into::into(dst as i32)))
 	}
 
-	fn bswap_32(x: u32) -> u32 {
+	fn mem_move(&mut self, context: InterpreterCallerContext)
-		x >> 24 | x >> 8 & 0xff00 | x << 8 & 0xff0000 | x << 24
+		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
+	{
+		//
+		// method signature:
+		//   fn memmove(dest: *const u8, src: *const u8, len: u32) -> *mut u8;
+		//
+
+		let len = context.value_stack.pop_as::<i32>()? as u32;
+		let src = context.value_stack.pop_as::<i32>()? as u32;
+		let dst = context.value_stack.pop_as::<i32>()? as u32;
+
+		self.charge(|schedule| schedule.wasm.mem_move as u64 * len as u64)?;
+
+		self.memory().copy(src as usize, dst as usize, len as usize)?;
+
+		Ok(Some(Into::into(dst as i32)))
+	}
+
+	fn mem_set(&mut self, context: InterpreterCallerContext)
+		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
+	{
+		//
+		// method signature:
+		//   fn memset(dest: *const u8, c: u32, len: u32) -> *mut u8;
+		//
+
+		let len = context.value_stack.pop_as::<i32>()? as u32;
+		let c = context.value_stack.pop_as::<i32>()? as u32;
+		let dst = context.value_stack.pop_as::<i32>()? as u32;
+
+		self.charge(|schedule| schedule.wasm.mem_set as u64 * len as u64)?;
+
+		self.memory().clear(dst as usize, c as u8, len as usize)?;
+
+		Ok(Some(Into::into(dst as i32)))
 	}
 
 	fn bitswap_i64(&mut self, context: InterpreterCallerContext)
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
-		let x1 = context.value_stack.pop_as::<i32>()?;
+		let x = context.value_stack.pop_as::<i64>()?;
-		let x2 = context.value_stack.pop_as::<i32>()?;
+		let result = x.swap_bytes();
 
-		let result = ((Runtime::bswap_32(x2 as u32) as u64) << 32
+		Ok(Some(result.into()))
-			| Runtime::bswap_32(x1 as u32) as u64) as i64;
-
-		self.return_i64(result)
 	}
 
 	fn user_panic(&mut self, context: InterpreterCallerContext)
@@ -606,13 +641,10 @@ impl<'a, 'b> Runtime<'a, 'b> {
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
 		let return_ptr = context.value_stack.pop_as::<i32>()? as u32;
-		let block_hi = context.value_stack.pop_as::<i32>()? as u32;
+		let block_num = context.value_stack.pop_as::<i64>()? as u64;
-		let block_lo = context.value_stack.pop_as::<i32>()? as u32;
 
 		self.charge(|schedule| schedule.blockhash_gas as u64)?;
 
-		let block_num = (block_hi as u64) << 32 | block_lo as u64;
-
 		trace!("Requesting block hash for block #{}", block_num);
 		let hash = self.ext.blockhash(&U256::from(block_num));
 
@@ -694,14 +726,14 @@ impl<'a, 'b> Runtime<'a, 'b> {
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
 		let timestamp = self.ext.env_info().timestamp as i64;
-		self.return_i64(timestamp)
+		Ok(Some(timestamp.into()))
 	}
 
 	fn block_number(&mut self, _context: InterpreterCallerContext)
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
-		let block_number: u64 = self.ext.env_info().number.into();
+		let block_number = self.ext.env_info().number as i64;
-		self.return_i64(block_number as i64)
+		Ok(Some(block_number.into()))
 	}
 
 	fn difficulty(&mut self, context: InterpreterCallerContext)
@@ -726,25 +758,6 @@ impl<'a, 'b> Runtime<'a, 'b> {
 		Ok(None)
 	}
 
-	fn return_i64(&mut self, val: i64) -> Result<Option<interpreter::RuntimeValue>, InterpreterError> {
-		self.charge(|schedule| schedule.wasm.static_u64 as u64)?;
-
-		let uval = val as u64;
-		let hi = (uval >> 32) as i32;
-		let lo = (uval << 32 >> 32) as i32;
-
-		let target = self.instance.module("contract").ok_or(UserTrap::Other)?;
-		target.execute_export(
-			"setTempRet0",
-			self.execution_params().add_argument(
-				interpreter::RuntimeValue::I32(hi).into()
-			),
-		)?;
-		Ok(Some(
-			(lo).into()
-		))
-	}
-
 	pub fn execution_params(&mut self) -> interpreter::ExecutionParams<UserTrap> {
 		use super::env;
 
@@ -812,10 +825,10 @@ impl<'a, 'b> interpreter::UserFunctionExecutor<UserTrap> for Runtime<'a, 'b> {
 		-> Result<Option<interpreter::RuntimeValue>, InterpreterError>
 	{
 		match name {
-			"_malloc" => {
+			"_ext_malloc" => {
 				self.malloc(context)
 			},
-			"_free" => {
+			"_ext_free" => {
 				// Since it is arena allocator, free does nothing
 				// todo: update if changed
 				self.user_noop(context)
@@ -853,6 +866,15 @@ impl<'a, 'b> interpreter::UserFunctionExecutor<UserTrap> for Runtime<'a, 'b> {
 			"_emscripten_memcpy_big" => {
 				self.mem_copy(context)
 			},
+			"_ext_memcpy" => {
+				self.mem_copy(context)
+			},
+			"_ext_memmove" => {
+				self.mem_move(context)
+			},
+			"_ext_memset" => {
+				self.mem_set(context)
+			},
 			"_llvm_bswap_i64" => {
 				self.bitswap_i64(context)
 			},

ethcore/wasm/src/tests.rs

@@ -60,7 +60,7 @@ fn empty() {
 		test_finalize(interpreter.exec(params, &mut ext)).unwrap()
 	};
 
-	assert_eq!(gas_left, U256::from(99_976));
+	assert_eq!(gas_left, U256::from(99_982));
 }
 
 // This test checks if the contract deserializes payload header properly.
@@ -89,7 +89,6 @@ fn logger() {
 		test_finalize(interpreter.exec(params, &mut ext)).unwrap()
 	};
 
-	assert_eq!(gas_left, U256::from(15_177));
 	let address_val: H256 = address.into();
 	assert_eq!(
 		ext.store.get(&"0100000000000000000000000000000000000000000000000000000000000000".parse().unwrap()).expect("storage key to exist"),
@@ -113,6 +112,7 @@ fn logger() {
 		U256::from(1_000_000_000),
 		"Logger sets 0x04 key to the trasferred value"
 	);
+	assert_eq!(gas_left, U256::from(19_143));
 }
 
 // This test checks if the contract can allocate memory and pass pointer to the result stream properly.
@@ -142,13 +142,12 @@ fn identity() {
 		}
 	};
 
-	assert_eq!(gas_left, U256::from(99_695));
-
 	assert_eq!(
 		Address::from_slice(&result),
 		sender,
 		"Idenity test contract does not return the sender passed"
 	);
+	assert_eq!(gas_left, U256::from(99_844));
 }
 
 // Dispersion test sends byte array and expect the contract to 'disperse' the original elements with
@@ -176,12 +175,12 @@ fn dispersion() {
 		}
 	};
 
-	assert_eq!(gas_left, U256::from(96_543));
 
 	assert_eq!(
 		result,
 		vec![0u8, 0, 125, 11, 197, 7, 255, 8, 19, 0]
 	);
+	assert_eq!(gas_left, U256::from(99_469));
 }
 
 #[test]
@@ -205,12 +204,11 @@ fn suicide_not() {
 		}
 	};
 
-	assert_eq!(gas_left, U256::from(96_822));
-
 	assert_eq!(
 		result,
 		vec![0u8]
 	);
+	assert_eq!(gas_left, U256::from(99_724));
 }
 
 #[test]
@@ -241,8 +239,8 @@ fn suicide() {
 		}
 	};
 
-	assert_eq!(gas_left, U256::from(96_580));
 	assert!(ext.suicides.contains(&refund));
+	assert_eq!(gas_left, U256::from(99_663));
 }
 
 #[test]
@@ -272,7 +270,7 @@ fn create() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Create,
-			gas: U256::from(62_324),
+			gas: U256::from(65_903),
 			sender_address: None,
 			receive_address: None,
 			value: Some(1_000_000_000.into()),
@@ -280,7 +278,7 @@ fn create() {
 			code_address: None,
 		}
 	));
-	assert_eq!(gas_left, U256::from(62_289));
+	assert_eq!(gas_left, U256::from(65_896));
 }
 
 
@@ -314,7 +312,7 @@ fn call_code() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Call,
-			gas: U256::from(95_585),
+			gas: U256::from(98_709),
 			sender_address: Some(sender),
 			receive_address: Some(receiver),
 			value: None,
@@ -322,11 +320,11 @@ fn call_code() {
 			code_address: Some("0d13710000000000000000000000000000000000".parse().unwrap()),
 		}
 	));
-	assert_eq!(gas_left, U256::from(90_665));
 
 	// siphash result
 	let res = LittleEndian::read_u32(&result[..]);
 	assert_eq!(res, 4198595614);
+	assert_eq!(gas_left, U256::from(93_851));
 }
 
 #[test]
@@ -359,7 +357,7 @@ fn call_static() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Call,
-			gas: U256::from(95_585),
+			gas: U256::from(98_709),
 			sender_address: Some(sender),
 			receive_address: Some(receiver),
 			value: None,
@@ -367,11 +365,12 @@ fn call_static() {
 			code_address: Some("13077bfb00000000000000000000000000000000".parse().unwrap()),
 		}
 	));
-	assert_eq!(gas_left, U256::from(90_665));
 
 	// siphash result
 	let res = LittleEndian::read_u32(&result[..]);
 	assert_eq!(res, 317632590);
+
+	assert_eq!(gas_left, U256::from(93_851));
 }
 
 // Realloc test
@@ -393,8 +392,8 @@ fn realloc() {
 				GasLeft::NeedsReturn { gas_left: gas, data: result, apply_state: _apply } => (gas, result.to_vec()),
 		}
 	};
-	assert_eq!(gas_left, U256::from(96_811));
 	assert_eq!(result, vec![0u8; 2]);
+	assert_eq!(gas_left, U256::from(99_787));
 }
 
 // Tests that contract's ability to read from a storage
@@ -419,8 +418,8 @@ fn storage_read() {
 		}
 	};
 
-	assert_eq!(gas_left, U256::from(96_645));
 	assert_eq!(Address::from(&result[12..32]), address);
+	assert_eq!(gas_left, U256::from(99_702));
 }
 
 // Tests keccak calculation
@@ -446,9 +445,97 @@ fn keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(80_452));
+	assert_eq!(gas_left, U256::from(84_520));
 }
 
+// memcpy test.
+#[test]
+fn memcpy() {
+	::ethcore_logger::init_log();
+	let code = load_sample!("mem.wasm");
+
+	let mut test_payload = Vec::with_capacity(8192);
+	for i in 0..8192 {
+		test_payload.push((i % 255) as u8);
+	}
+	let mut data = vec![0u8];
+	data.extend(&test_payload);
+
+	let mut params = ActionParams::default();
+	params.gas = U256::from(100_000);
+	params.code = Some(Arc::new(code));
+	params.data = Some(data);
+	let mut ext = FakeExt::new();
+
+	let (gas_left, result) = {
+		let mut interpreter = wasm_interpreter();
+		let result = interpreter.exec(params, &mut ext).expect("Interpreter to execute without any errors");
+		match result {
+			GasLeft::Known(_) => { panic!("mem should return payload"); },
+			GasLeft::NeedsReturn { gas_left: gas, data: result, apply_state: _apply } => (gas, result.to_vec()),
+		}
+	};
+
+	assert_eq!(result, test_payload);
+	assert_eq!(gas_left, U256::from(75_324));
+}
+
+// memmove test.
+#[test]
+fn memmove() {
+	::ethcore_logger::init_log();
+	let code = load_sample!("mem.wasm");
+
+	let mut test_payload = Vec::with_capacity(8192);
+	for i in 0..8192 {
+		test_payload.push((i % 255) as u8);
+	}
+	let mut data = vec![1u8];
+	data.extend(&test_payload);
+
+	let mut params = ActionParams::default();
+	params.gas = U256::from(100_000);
+	params.code = Some(Arc::new(code));
+	params.data = Some(data);
+	let mut ext = FakeExt::new();
+
+	let (gas_left, result) = {
+		let mut interpreter = wasm_interpreter();
+		let result = interpreter.exec(params, &mut ext).expect("Interpreter to execute without any errors");
+		match result {
+			GasLeft::Known(_) => { panic!("mem should return payload"); },
+			GasLeft::NeedsReturn { gas_left: gas, data: result, apply_state: _apply } => (gas, result.to_vec()),
+		}
+	};
+
+	assert_eq!(result, test_payload);
+	assert_eq!(gas_left, U256::from(75_324));
+}
+
+// memset test
+#[test]
+fn memset() {
+	::ethcore_logger::init_log();
+	let code = load_sample!("mem.wasm");
+
+	let mut params = ActionParams::default();
+	params.gas = U256::from(100_000);
+	params.code = Some(Arc::new(code));
+	params.data = Some(vec![2u8,  228u8]);
+	let mut ext = FakeExt::new();
+
+	let (gas_left, result) = {
+		let mut interpreter = wasm_interpreter();
+		let result = interpreter.exec(params, &mut ext).expect("Interpreter to execute without any errors");
+		match result {
+			GasLeft::Known(_) => { panic!("mem should return payload"); },
+			GasLeft::NeedsReturn { gas_left: gas, data: result, apply_state: _apply } => (gas, result.to_vec()),
+		}
+	};
+
+	assert_eq!(result, vec![228u8; 8192]);
+	assert_eq!(gas_left, U256::from(75_324));
+}
 
 macro_rules! reqrep_test {
 	($name: expr, $input: expr) => {
@@ -500,11 +587,11 @@ fn math_add() {
 		}
 	).expect("Interpreter to execute without any errors");
 
-	assert_eq!(gas_left, U256::from(94_666));
 	assert_eq!(
 		U256::from_dec_str("1888888888888888888888888888887").unwrap(),
 		(&result[..]).into()
 	);
+	assert_eq!(gas_left, U256::from(98_576));
 }
 
 // multiplication
@@ -522,11 +609,11 @@ fn math_mul() {
 		}
 	).expect("Interpreter to execute without any errors");
 
-	assert_eq!(gas_left, U256::from(93_719));
 	assert_eq!(
 		U256::from_dec_str("888888888888888888888888888887111111111111111111111111111112").unwrap(),
 		(&result[..]).into()
 	);
+	assert_eq!(gas_left, U256::from(97_726));
 }
 
 // subtraction
@@ -544,11 +631,11 @@ fn math_sub() {
 		}
 	).expect("Interpreter to execute without any errors");
 
-	assert_eq!(gas_left, U256::from(94_718));
 	assert_eq!(
 		U256::from_dec_str("111111111111111111111111111111").unwrap(),
 		(&result[..]).into()
 	);
+	assert_eq!(gas_left, U256::from(98_568));
 }
 
 // subtraction with overflow
@@ -566,7 +653,10 @@ fn math_sub_with_overflow() {
 		}
 	);
 
-	assert_eq!(result, Err(vm::Error::Wasm("Wasm runtime error: User(Panic(\"arithmetic operation overflow\"))".into())));
+	match result {
+		Err(vm::Error::Wasm(_)) => {},
+		_ => panic!("Unexpected result {:?}", result),
+	}
 }
 
 #[test]
@@ -583,11 +673,11 @@ fn math_div() {
 		}
 	).expect("Interpreter to execute without any errors");
 
-	assert_eq!(gas_left, U256::from(86_996));
 	assert_eq!(
 		U256::from_dec_str("1125000").unwrap(),
 		(&result[..]).into()
 	);
+	assert_eq!(gas_left, U256::from(91_564));
 }
 
 // This test checks the ability of wasm contract to invoke
@@ -675,7 +765,7 @@ fn externs() {
 		"Gas limit requested and returned does not match"
 	);
 
-	assert_eq!(gas_left, U256::from(91_857));
+	assert_eq!(gas_left, U256::from(97_740));
 }
 
 #[test]
@@ -701,7 +791,7 @@ fn embedded_keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(80_452));
+	assert_eq!(gas_left, U256::from(84_520));
 }
 
 /// This test checks the correctness of log extern
@@ -736,5 +826,5 @@ fn events() {
 	assert_eq!(&log_entry.data, b"gnihtemos");
 
 	assert_eq!(&result, b"gnihtemos");
-	assert_eq!(gas_left, U256::from(78039));
+	assert_eq!(gas_left, U256::from(82_721));
-}
+}