GasCosts.md

Current (Istanbul) costs

With Istanbul rules, EIP-2200: https://eips.ethereum.org/EIPS/eip-2200#test-cases, the following gas usages apply for the various scenarions below:

Code	Used Gas	Refund	Original	1st	2nd	3rd	Effective gas (after refund)
0x60006000556000600055	1612	0	0	0	0		1612
0x60006000556001600055	20812	0	0	0	1		20812
0x60016000556000600055	20812	19200	0	1	0		1612
0x60016000556002600055	20812	0	0	1	2		20812
0x60016000556001600055	20812	0	0	1	1		20812
0x60006000556000600055	5812	15000	1	0	0		-9188
0x60006000556001600055	5812	4200	1	0	1		1612
0x60006000556002600055	5812	0	1	0	2		5812
0x60026000556000600055	5812	15000	1	2	0		-9188
0x60026000556003600055	5812	0	1	2	3		5812
0x60026000556001600055	5812	4200	1	2	1		1612
0x60026000556002600055	5812	0	1	2	2		5812
0x60016000556000600055	5812	15000	1	1	0		-9188
0x60016000556002600055	5812	0	1	1	2		5812
0x60016000556001600055	1612	0	1	1	1		1612
0x600160005560006000556001600055	40818	19200	0	1	0	1	21618
0x600060005560016000556000600055	10818	19200	1	0	1	0	-8382

Berlin costs

With Berlin, and EIP-2929, the gas costs changes. Note, there is a difference between 'hot' and 'cold' slots. The following table is generated based on the slot in question (0) being 'cold'.

Code	Used Gas	Refund	Original	1st	2nd	3rd	Effective gas (after refund)
0x60006000556000600055	2312	0	0	0	0		2312
0x60006000556001600055	22212	0	0	0	1		22212
0x60016000556000600055	22212	19900	0	1	0		2312
0x60016000556002600055	22212	0	0	1	2		22212
0x60016000556001600055	22212	0	0	1	1		22212
0x60006000556000600055	5112	15000	1	0	0		-9888
0x60006000556001600055	5112	2800	1	0	1		2312
0x60006000556002600055	5112	0	1	0	2		5112
0x60026000556000600055	5112	15000	1	2	0		-9888
0x60026000556003600055	5112	0	1	2	3		5112
0x60026000556001600055	5112	2800	1	2	1		2312
0x60026000556002600055	5112	0	1	2	2		5112
0x60016000556000600055	5112	15000	1	1	0		-9888
0x60016000556002600055	5112	0	1	1	2		5112
0x60016000556001600055	2312	0	1	1	1		2312
0x600160005560006000556001600055	42218	19900	0	1	0	1	22318
0x600060005560016000556000600055	8018	17800	1	0	1	0	-9782

If the slot is already 'warm', this is the corresponding table:

Code	Used Gas	Refund	Original	1st	2nd	3rd	Effective gas (after refund)
0x60006000556000600055	212	0	0	0	0		212
0x60006000556001600055	20112	0	0	0	1		20112
0x60016000556000600055	20112	19900	0	1	0		212
0x60016000556002600055	20112	0	0	1	2		20112
0x60016000556001600055	20112	0	0	1	1		20112
0x60006000556000600055	3012	15000	1	0	0		-11988
0x60006000556001600055	3012	2800	1	0	1		212
0x60006000556002600055	3012	0	1	0	2		3012
0x60026000556000600055	3012	15000	1	2	0		-11988
0x60026000556003600055	3012	0	1	2	3		3012
0x60026000556001600055	3012	2800	1	2	1		212
0x60026000556002600055	3012	0	1	2	2		3012
0x60016000556000600055	3012	15000	1	1	0		-11988
0x60016000556002600055	3012	0	1	1	2		3012
0x60016000556001600055	212	0	1	1	1		212
0x600160005560006000556001600055	40118	19900	0	1	0	1	20218
0x600060005560016000556000600055	5918	17800	1	0	1	0	-11882

Without refunds

If refunds were to be removed, this would be the comparative table

Code	Original	1st	2nd	3rd	Istanbul	Berlin (cold)	Berlin (hot)	Berlin (hot)+norefund
0x60006000556000600055	0	0	0		1612	2312	212	212
0x60006000556001600055	0	0	1		20812	22212	20112	20112
0x60016000556000600055	0	1	0		1612	2312	212	20112
0x60016000556002600055	0	1	2		20812	22212	20112	20112
0x60016000556001600055	0	1	1		20812	22212	20112	20112
0x60006000556000600055	1	0	0		-9188	-9888	-11988	3012
0x60006000556001600055	1	0	1		1612	2312	212	3012
0x60006000556002600055	1	0	2		5812	5112	3012	3012
0x60026000556000600055	1	2	0		-9188	-9888	-11988	3012
0x60026000556003600055	1	2	3		5812	5112	3012	3012
0x60026000556001600055	1	2	1		1612	2312	212	3012
0x60026000556002600055	1	2	2		5812	5112	3012	3012
0x60016000556000600055	1	1	0		-9188	-9888	-11988	3012
0x60016000556002600055	1	1	2		5812	5112	3012	3012
0x60016000556001600055	1	1	1		1612	2312	212	212
0x600160005560006000556001600055	0	1	0	1	21618	22318	20218	40118
0x600060005560016000556000600055	1	0	1	0	-8382	-9782	-11882	5918

In partcular, the following cases become more expensive:

• '0-1-0' goes from 10K to 20K,
• '0-1-0-1' goes from 21K to 40K,

For these cases, a better scheme under the no-refund rule would be to use non-zero slots, e.g. '1-2-1' and thus wind up with 3K gas.

Note: In reality, there are never a negative gas cost, since the refund is capped at 0.5 * gasUsed. However, these tables show the negative values, since in a more real-world scenarion would likely spend the extra gas on other operations.'

Full implementation, minus some boilerplate code for actually defining the fork:

diff --git a/core/state_transition.go b/core/state_transition.go
index a8d1936c1f..7efe2ad888 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -262,7 +262,8 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 		st.state.SetNonce(msg.From(), st.state.GetNonce(sender.Address())+1)
 		ret, st.gas, vmerr = st.evm.Call(sender, st.to(), st.data, st.gas, st.value)
 	}
-	st.refundGas()
+	refundsEnabled := !st.evm.ChainConfig().IsRefundDisabledFork(st.evm.Context.BlockNumber)
+	st.refundGas(refundsEnabled)
 	st.state.AddBalance(st.evm.Context.Coinbase, new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), st.gasPrice))
 
 	return &ExecutionResult{
@@ -272,13 +273,15 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 	}, nil
 }
 
-func (st *StateTransition) refundGas() {
+func (st *StateTransition) refundGas(refundsEnabled bool) {
 	// Apply refund counter, capped to half of the used gas.
-	refund := st.gasUsed() / 2
-	if refund > st.state.GetRefund() {
-		refund = st.state.GetRefund()
+	if refundsEnabled {
+		refund := st.gasUsed() / 2
+		if refund > st.state.GetRefund() {
+			refund = st.state.GetRefund()
+		}
+		st.gas += refund
 	}
-	st.gas += refund
 
 	// Return ETH for remaining gas, exchanged at the original rate.
 	remaining := new(big.Int).Mul(new(big.Int).SetUint64(st.gas), st.gasPrice)