442 lines
16 KiB
Go
442 lines
16 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"errors"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/math"
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"github.com/ethereum/go-ethereum/params"
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)
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// memoryGasCost calculates the quadratic gas for memory expansion. It does so
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// only for the memory region that is expanded, not the total memory.
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func memoryGasCost(mem *Memory, newMemSize uint64) (uint64, error) {
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if newMemSize == 0 {
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return 0, nil
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}
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// The maximum that will fit in a uint64 is max_word_count - 1. Anything above
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// that will result in an overflow. Additionally, a newMemSize which results in
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// a newMemSizeWords larger than 0xFFFFFFFF will cause the square operation to
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// overflow. The constant 0x1FFFFFFFE0 is the highest number that can be used
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// without overflowing the gas calculation.
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if newMemSize > 0x1FFFFFFFE0 {
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return 0, ErrGasUintOverflow
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}
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newMemSizeWords := toWordSize(newMemSize)
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newMemSize = newMemSizeWords * 32
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if newMemSize > uint64(mem.Len()) {
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square := newMemSizeWords * newMemSizeWords
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linCoef := newMemSizeWords * params.MemoryGas
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quadCoef := square / params.QuadCoeffDiv
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newTotalFee := linCoef + quadCoef
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fee := newTotalFee - mem.lastGasCost
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mem.lastGasCost = newTotalFee
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return fee, nil
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}
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return 0, nil
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}
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// memoryCopierGas creates the gas functions for the following opcodes, and takes
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// the stack position of the operand which determines the size of the data to copy
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// as argument:
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// CALLDATACOPY (stack position 2)
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// CODECOPY (stack position 2)
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// EXTCODECOPY (stack poition 3)
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// RETURNDATACOPY (stack position 2)
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func memoryCopierGas(stackpos int) gasFunc {
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return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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// Gas for expanding the memory
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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// And gas for copying data, charged per word at param.CopyGas
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words, overflow := stack.Back(stackpos).Uint64WithOverflow()
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if overflow {
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return 0, ErrGasUintOverflow
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}
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if words, overflow = math.SafeMul(toWordSize(words), params.CopyGas); overflow {
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return 0, ErrGasUintOverflow
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}
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if gas, overflow = math.SafeAdd(gas, words); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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}
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var (
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gasCallDataCopy = memoryCopierGas(2)
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gasCodeCopy = memoryCopierGas(2)
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gasExtCodeCopy = memoryCopierGas(3)
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gasReturnDataCopy = memoryCopierGas(2)
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)
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func gasSStore(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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var (
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y, x = stack.Back(1), stack.Back(0)
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current = evm.StateDB.GetState(contract.Address(), common.Hash(x.Bytes32()))
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)
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// The legacy gas metering only takes into consideration the current state
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// Legacy rules should be applied if we are in Petersburg (removal of EIP-1283)
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// OR Constantinople is not active
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if evm.chainRules.IsPetersburg || !evm.chainRules.IsConstantinople {
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// This checks for 3 scenario's and calculates gas accordingly:
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//
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// 1. From a zero-value address to a non-zero value (NEW VALUE)
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// 2. From a non-zero value address to a zero-value address (DELETE)
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// 3. From a non-zero to a non-zero (CHANGE)
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switch {
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case current == (common.Hash{}) && y.Sign() != 0: // 0 => non 0
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return params.SstoreSetGas, nil
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case current != (common.Hash{}) && y.Sign() == 0: // non 0 => 0
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evm.StateDB.AddRefund(params.SstoreRefundGas)
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return params.SstoreClearGas, nil
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default: // non 0 => non 0 (or 0 => 0)
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return params.SstoreResetGas, nil
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}
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}
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// The new gas metering is based on net gas costs (EIP-1283):
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//
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// 1. If current value equals new value (this is a no-op), 200 gas is deducted.
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// 2. If current value does not equal new value
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// 2.1. If original value equals current value (this storage slot has not been changed by the current execution context)
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// 2.1.1. If original value is 0, 20000 gas is deducted.
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// 2.1.2. Otherwise, 5000 gas is deducted. If new value is 0, add 15000 gas to refund counter.
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// 2.2. If original value does not equal current value (this storage slot is dirty), 200 gas is deducted. Apply both of the following clauses.
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// 2.2.1. If original value is not 0
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// 2.2.1.1. If current value is 0 (also means that new value is not 0), remove 15000 gas from refund counter. We can prove that refund counter will never go below 0.
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// 2.2.1.2. If new value is 0 (also means that current value is not 0), add 15000 gas to refund counter.
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// 2.2.2. If original value equals new value (this storage slot is reset)
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// 2.2.2.1. If original value is 0, add 19800 gas to refund counter.
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// 2.2.2.2. Otherwise, add 4800 gas to refund counter.
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value := common.Hash(y.Bytes32())
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if current == value { // noop (1)
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return params.NetSstoreNoopGas, nil
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}
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original := evm.StateDB.GetCommittedState(contract.Address(), common.Hash(x.Bytes32()))
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if original == current {
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if original == (common.Hash{}) { // create slot (2.1.1)
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return params.NetSstoreInitGas, nil
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}
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if value == (common.Hash{}) { // delete slot (2.1.2b)
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evm.StateDB.AddRefund(params.NetSstoreClearRefund)
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}
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return params.NetSstoreCleanGas, nil // write existing slot (2.1.2)
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}
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if original != (common.Hash{}) {
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if current == (common.Hash{}) { // recreate slot (2.2.1.1)
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evm.StateDB.SubRefund(params.NetSstoreClearRefund)
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} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
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evm.StateDB.AddRefund(params.NetSstoreClearRefund)
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}
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}
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if original == value {
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if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
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evm.StateDB.AddRefund(params.NetSstoreResetClearRefund)
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} else { // reset to original existing slot (2.2.2.2)
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evm.StateDB.AddRefund(params.NetSstoreResetRefund)
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}
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}
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return params.NetSstoreDirtyGas, nil
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}
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// 0. If *gasleft* is less than or equal to 2300, fail the current call.
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// 1. If current value equals new value (this is a no-op), SLOAD_GAS is deducted.
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// 2. If current value does not equal new value:
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// 2.1. If original value equals current value (this storage slot has not been changed by the current execution context):
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// 2.1.1. If original value is 0, SSTORE_SET_GAS (20K) gas is deducted.
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// 2.1.2. Otherwise, SSTORE_RESET_GAS gas is deducted. If new value is 0, add SSTORE_CLEARS_SCHEDULE to refund counter.
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// 2.2. If original value does not equal current value (this storage slot is dirty), SLOAD_GAS gas is deducted. Apply both of the following clauses:
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// 2.2.1. If original value is not 0:
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// 2.2.1.1. If current value is 0 (also means that new value is not 0), subtract SSTORE_CLEARS_SCHEDULE gas from refund counter.
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// 2.2.1.2. If new value is 0 (also means that current value is not 0), add SSTORE_CLEARS_SCHEDULE gas to refund counter.
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// 2.2.2. If original value equals new value (this storage slot is reset):
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// 2.2.2.1. If original value is 0, add SSTORE_SET_GAS - SLOAD_GAS to refund counter.
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// 2.2.2.2. Otherwise, add SSTORE_RESET_GAS - SLOAD_GAS gas to refund counter.
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func gasSStoreEIP2200(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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// If we fail the minimum gas availability invariant, fail (0)
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if contract.Gas <= params.SstoreSentryGasEIP2200 {
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return 0, errors.New("not enough gas for reentrancy sentry")
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}
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// Gas sentry honoured, do the actual gas calculation based on the stored value
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var (
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y, x = stack.Back(1), stack.Back(0)
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current = evm.StateDB.GetState(contract.Address(), common.Hash(x.Bytes32()))
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)
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value := common.Hash(y.Bytes32())
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if current == value { // noop (1)
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return params.SloadGasEIP2200, nil
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}
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original := evm.StateDB.GetCommittedState(contract.Address(), common.Hash(x.Bytes32()))
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if original == current {
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if original == (common.Hash{}) { // create slot (2.1.1)
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return params.SstoreSetGasEIP2200, nil
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}
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if value == (common.Hash{}) { // delete slot (2.1.2b)
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evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
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}
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return params.SstoreResetGasEIP2200, nil // write existing slot (2.1.2)
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}
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if original != (common.Hash{}) {
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if current == (common.Hash{}) { // recreate slot (2.2.1.1)
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evm.StateDB.SubRefund(params.SstoreClearsScheduleRefundEIP2200)
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} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
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evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
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}
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}
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if original == value {
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if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
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evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - params.SloadGasEIP2200)
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} else { // reset to original existing slot (2.2.2.2)
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evm.StateDB.AddRefund(params.SstoreResetGasEIP2200 - params.SloadGasEIP2200)
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}
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}
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return params.SloadGasEIP2200, nil // dirty update (2.2)
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}
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func makeGasLog(n uint64) gasFunc {
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return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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requestedSize, overflow := stack.Back(1).Uint64WithOverflow()
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if overflow {
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return 0, ErrGasUintOverflow
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}
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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if gas, overflow = math.SafeAdd(gas, params.LogGas); overflow {
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return 0, ErrGasUintOverflow
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}
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if gas, overflow = math.SafeAdd(gas, n*params.LogTopicGas); overflow {
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return 0, ErrGasUintOverflow
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}
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var memorySizeGas uint64
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if memorySizeGas, overflow = math.SafeMul(requestedSize, params.LogDataGas); overflow {
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return 0, ErrGasUintOverflow
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}
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if gas, overflow = math.SafeAdd(gas, memorySizeGas); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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}
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func gasSha3(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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wordGas, overflow := stack.Back(1).Uint64WithOverflow()
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if overflow {
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return 0, ErrGasUintOverflow
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}
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if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.Sha3WordGas); overflow {
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return 0, ErrGasUintOverflow
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}
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if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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// pureMemoryGascost is used by several operations, which aside from their
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// static cost have a dynamic cost which is solely based on the memory
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// expansion
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func pureMemoryGascost(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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return memoryGasCost(mem, memorySize)
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}
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var (
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gasReturn = pureMemoryGascost
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gasRevert = pureMemoryGascost
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gasMLoad = pureMemoryGascost
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gasMStore8 = pureMemoryGascost
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gasMStore = pureMemoryGascost
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gasCreate = pureMemoryGascost
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)
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func gasCreate2(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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wordGas, overflow := stack.Back(2).Uint64WithOverflow()
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if overflow {
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return 0, ErrGasUintOverflow
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}
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if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.Sha3WordGas); overflow {
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return 0, ErrGasUintOverflow
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}
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if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasExpFrontier(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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expByteLen := uint64((stack.data[stack.len()-2].BitLen() + 7) / 8)
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var (
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gas = expByteLen * params.ExpByteFrontier // no overflow check required. Max is 256 * ExpByte gas
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overflow bool
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)
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if gas, overflow = math.SafeAdd(gas, params.ExpGas); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasExpEIP158(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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expByteLen := uint64((stack.data[stack.len()-2].BitLen() + 7) / 8)
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var (
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gas = expByteLen * params.ExpByteEIP158 // no overflow check required. Max is 256 * ExpByte gas
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overflow bool
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)
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if gas, overflow = math.SafeAdd(gas, params.ExpGas); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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var (
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gas uint64
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transfersValue = !stack.Back(2).IsZero()
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address = common.Address(stack.Back(1).Bytes20())
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)
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if evm.chainRules.IsEIP158 {
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if transfersValue && evm.StateDB.Empty(address) {
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gas += params.CallNewAccountGas
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}
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} else if !evm.StateDB.Exist(address) {
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gas += params.CallNewAccountGas
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}
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if transfersValue {
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gas += params.CallValueTransferGas
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}
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memoryGas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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var overflow bool
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if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
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return 0, ErrGasUintOverflow
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}
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evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
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if err != nil {
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return 0, err
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}
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if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasCallCode(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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memoryGas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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var (
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gas uint64
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overflow bool
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)
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if stack.Back(2).Sign() != 0 {
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gas += params.CallValueTransferGas
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}
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if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
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return 0, ErrGasUintOverflow
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}
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evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
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if err != nil {
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return 0, err
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}
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if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasDelegateCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
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if err != nil {
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return 0, err
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}
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var overflow bool
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if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasStaticCall(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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gas, err := memoryGasCost(mem, memorySize)
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if err != nil {
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return 0, err
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}
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evm.callGasTemp, err = callGas(evm.chainRules.IsEIP150, contract.Gas, gas, stack.Back(0))
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if err != nil {
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return 0, err
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}
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var overflow bool
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if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
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return 0, ErrGasUintOverflow
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}
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return gas, nil
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}
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func gasSelfdestruct(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
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var gas uint64
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// EIP150 homestead gas reprice fork:
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if evm.chainRules.IsEIP150 {
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gas = params.SelfdestructGasEIP150
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var address = common.Address(stack.Back(0).Bytes20())
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if evm.chainRules.IsEIP158 {
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// if empty and transfers value
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if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).Sign() != 0 {
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gas += params.CreateBySelfdestructGas
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}
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} else if !evm.StateDB.Exist(address) {
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gas += params.CreateBySelfdestructGas
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}
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}
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if !evm.StateDB.HasSuicided(contract.Address()) {
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evm.StateDB.AddRefund(params.SelfdestructRefundGas)
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}
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return gas, nil
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}
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