precompile_utils/evm/
costs.rs

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1// This file is part of Frontier.
2
3// Copyright (c) Moonsong Labs.
4// Copyright (C) Parity Technologies (UK) Ltd.
5// SPDX-License-Identifier: Apache-2.0
6
7// Licensed under the Apache License, Version 2.0 (the "License");
8// you may not use this file except in compliance with the License.
9// You may obtain a copy of the License at
10//
11// 	http://www.apache.org/licenses/LICENSE-2.0
12//
13// Unless required by applicable law or agreed to in writing, software
14// distributed under the License is distributed on an "AS IS" BASIS,
15// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16// See the License for the specific language governing permissions and
17// limitations under the License.
18
19//! Cost calculations.
20//! TODO: PR EVM to make those cost calculations public.
21
22use crate::EvmResult;
23use fp_evm::{ExitError, PrecompileFailure};
24use sp_core::U256;
25
26pub fn log_costs(topics: usize, data_len: usize) -> EvmResult<u64> {
27	// Cost calculation is copied from EVM code that is not publicly exposed by the crates.
28	// https://github.com/rust-ethereum/evm/blob/master/src/standard/gasometer/costs.rs#L148
29
30	const G_LOG: u64 = 375;
31	const G_LOGDATA: u64 = 8;
32	const G_LOGTOPIC: u64 = 375;
33
34	let topic_cost = G_LOGTOPIC
35		.checked_mul(topics as u64)
36		.ok_or(PrecompileFailure::Error {
37			exit_status: ExitError::OutOfGas,
38		})?;
39
40	let data_cost = G_LOGDATA
41		.checked_mul(data_len as u64)
42		.ok_or(PrecompileFailure::Error {
43			exit_status: ExitError::OutOfGas,
44		})?;
45
46	G_LOG
47		.checked_add(topic_cost)
48		.ok_or(PrecompileFailure::Error {
49			exit_status: ExitError::OutOfGas,
50		})?
51		.checked_add(data_cost)
52		.ok_or(PrecompileFailure::Error {
53			exit_status: ExitError::OutOfGas,
54		})
55}
56
57// Compute the cost of doing a subcall.
58// Some parameters cannot be known in advance, so we estimate the worst possible cost.
59pub fn call_cost(value: U256, config: &evm::Config) -> u64 {
60	// Copied from EVM code since not public.
61	pub const G_CALLVALUE: u64 = 9000;
62	pub const G_NEWACCOUNT: u64 = 25000;
63
64	fn address_access_cost(is_cold: bool, regular_value: u64, config: &evm::Config) -> u64 {
65		if config.increase_state_access_gas {
66			if is_cold {
67				config.gas_account_access_cold
68			} else {
69				config.gas_storage_read_warm
70			}
71		} else {
72			regular_value
73		}
74	}
75
76	fn xfer_cost(is_call_or_callcode: bool, transfers_value: bool) -> u64 {
77		if is_call_or_callcode && transfers_value {
78			G_CALLVALUE
79		} else {
80			0
81		}
82	}
83
84	fn new_cost(
85		is_call_or_staticcall: bool,
86		new_account: bool,
87		transfers_value: bool,
88		config: &evm::Config,
89	) -> u64 {
90		let eip161 = !config.empty_considered_exists;
91		if is_call_or_staticcall {
92			if eip161 {
93				if transfers_value && new_account {
94					G_NEWACCOUNT
95				} else {
96					0
97				}
98			} else if new_account {
99				G_NEWACCOUNT
100			} else {
101				0
102			}
103		} else {
104			0
105		}
106	}
107
108	let transfers_value = value != U256::default();
109	let is_cold = true;
110	let is_call_or_callcode = true;
111	let is_call_or_staticcall = true;
112	let new_account = true;
113
114	address_access_cost(is_cold, config.gas_call, config)
115		+ xfer_cost(is_call_or_callcode, transfers_value)
116		+ new_cost(is_call_or_staticcall, new_account, transfers_value, config)
117}
precompile_utils/evm/costs.rs

precompile_utils/evm/
costs.rs
