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EIP-2929: Gas cost increases for state access opcodes #289

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@yperbasis yperbasis commented Feb 15, 2021

Keeping as draft until ethereum/evmc#571 is merged.

@@ -20,6 +20,13 @@ evmc_status_code call(ExecutionState& state) noexcept

state.stack.push(0); // Assume failure.

if (state.rev >= EVMC_BERLIN && state.host.access_account(dst) == EVMC_COLD_ACCESS)
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Minimal improvement here would be to merge access_account() and account_exists(). I believe the account can have 3 statuses then: hot, cold, non-existing.

BTW, can a non-existing account become hot?

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@yperbasis yperbasis Feb 16, 2021

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Not sure that merging access_account() with account_exists() is worth it. It might save a function call, but the two are quite different: account_exists() (EIP-161) is a constant operation that doesn't change anything, while access_account() modifies accessed_addresses substate (EIP-2929).

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SELFDESTRUCT puts non-existing beneficiary into a warm set, the same I thihk with calls, so warm/cold and existing/non-existing seem to be orthogonal.

One could also think that account_exists puts non-existing account into a warm set, it's used only in SELFDESTRUCT and calls which do it, and it would reflect reality of updating non-existence caches in clients.

return EVMC_OUT_OF_GAS;
}

x = intx::be::load<uint256>(state.host.get_balance(addr));
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Here and with other methods accessing information about accounts the get_balance() can be extended to return both account status and the balance. The gas check should be done after the call, although I'm sure @holiman would be happy with such implementation. But my reasoning that even "access account" makes it hot so it can also return the balance in the same time.

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@yperbasis yperbasis Feb 16, 2021

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That was my thinking at first with sload, to return both the value and the access status. But then I realised that it complicates the API. I believe that having a separate method specifically to record access in the sense of EIP-2929 leads to a simpler API compared to reporting access status in various methods. The performance overhead shouldn't be too big, just an extra function call.

@yperbasis yperbasis changed the title [WIP] EIP-2929: Gas cost increases for state access opcodes EIP-2929: Gas cost increases for state access opcodes Feb 19, 2021
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Codecov Report

Merging #289 (cc7614b) into master (b9facfa) will decrease coverage by 0.67%.
The diff coverage is 60.93%.

❗ Current head cc7614b differs from pull request most recent head 3b07834. Consider uploading reports for the commit 3b07834 to get more accurate results

@@            Coverage Diff             @@
##           master     #289      +/-   ##
==========================================
- Coverage   99.75%   99.07%   -0.68%     
==========================================
  Files          24       24              
  Lines        3659     3694      +35     
==========================================
+ Hits         3650     3660      +10     
- Misses          9       34      +25     
Flag Coverage Δ
unittests 99.07% <60.93%> (-0.68%) ⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files Coverage Δ
lib/evmone/instructions.cpp 100.00% <ø> (ø)
lib/evmone/instructions_calls.cpp 97.93% <33.33%> (-2.07%) ⬇️
lib/evmone/baseline.cpp 98.42% <50.00%> (-1.40%) ⬇️
lib/evmone/instructions.hpp 96.58% <66.66%> (-3.42%) ⬇️

@chfast chfast force-pushed the eip-2929 branch 4 times, most recently from c53634e to 915c089 Compare April 7, 2021 13:37
@chfast chfast changed the base branch from master to evmc April 7, 2021 13:38
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chfast commented Apr 7, 2021

Consensus tests are going to be updated later in #298.

@chfast chfast force-pushed the eip-2929 branch 4 times, most recently from 6f18e82 to c63312d Compare April 8, 2021 15:15

#include <evmc/instructions.h>
#include <array>

namespace evmone::instr
{
/// EIP-2929 constants (https://eips.ethereum.org/EIPS/eip-2929).
inline constexpr auto cold_sload_cost = 2100;
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Not sure what we're going to do with these constants if they change in future forks... Mabye just prepend with berlin_. But I guess it's ok to leave like this now.

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@chfast chfast Apr 9, 2021

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True. But it would be easy to move them to constexpr array. E.g. instr::constants[EVMC_BERLIN].cold_sload_cost.

inline constexpr auto cold_sload_cost = 2100;
inline constexpr auto cold_account_access_cost = 2600;
inline constexpr auto warm_storage_read_cost = 100;
inline constexpr auto additional_cold_account_access_cost =
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Maybe introduce also additional_sload_cost and use it in sload for consistency.

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I used the name, but only locally where it is used. Also explained the global definition.


const auto& r = host.recorded_account_accesses;
ASSERT_EQ(r.size(), 24);
EXPECT_EQ(r[0], msg.sender);
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Maybe could be better-looking with some fancy assert

EXPECT_THAT(r, ElementsAre(msg.sender, msg.destination, ...));

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This is fine so I don't need to count these in my head. And I don't need to import Google Mock.

state.host.get_storage(state.msg->destination, intx::be::store<evmc::bytes32>(x)));
const auto key = intx::be::store<evmc::bytes32>(x);

if (state.rev >= EVMC_BERLIN &&
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Is there any measureable performance diff for these revision checks? Should we templetize based on version at some point?

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There are not benchmarks for state access. I could add some, but these are may not be "portable" because depending on the pre-state initialization.

I don't think it is worth duplicating the code with templates for these. However, it may be good to priorities the most recent revision in the code.

@@ -316,7 +316,7 @@ constexpr std::array<instruction_exec_fn, 256> instruction_implementations = [](
table[OP_SHL] = op<shl>;
table[OP_SHR] = op<shr>;
table[OP_SAR] = op<sar>;
table[OP_EXTCODEHASH] = op<extcodehash>;
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Why is this removed here?

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Oh yeah, I was wandering the same @yperbasis.

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Oh, I simply removed duplicated code; see line 323.

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Ah ok. I will sort these in separate PR then.

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axic commented Apr 20, 2021

This was merged under #301.

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6 participants