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fix: charge dynamic gas for EXP and LOG in multipass,align log hashing #278

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Merged
zoowii merged 4 commits into from
Jan 28, 2026
Merged

fix: charge dynamic gas for EXP and LOG in multipass,align log hashing #278

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f1aa7ac
fix: charge dynamic gas for EXP and LOG in multipass,align log hashing
ZR74 Jan 22, 2026
f50b449
style: format check
ZR74 Jan 22, 2026
f98db55
fix: exclude CALL stipend from callee gas charge
ZR74 Jan 26, 2026
b5246ec
fix: align exp behavior with interpreter
ZR74 Jan 26, 2026
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35 changes: 12 additions & 23 deletions src/compiler/evm_frontend/evm_imported.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -227,31 +227,16 @@ const intx::uint256 *evmGetMulMod(zen::runtime::EVMInstance *Instance,
const intx::uint256 *evmGetExp(zen::runtime::EVMInstance *Instance,
const intx::uint256 &Base,
const intx::uint256 &Exponent) {
// Handle edge cases
if (Exponent == 0) {
return storeUint256Result(intx::uint256{1});
}
if (Base == 0) {
return storeUint256Result(intx::uint256{0});
}
if (Exponent == 1) {
return storeUint256Result(Base);
}
// EIP-160: 50 gas per byte of exponent (pre-Spurious Dragon is cheaper).
const uint64_t ExponentByteSize = intx::count_significant_bytes(Exponent);
const auto Rev = Instance->getRevision();
const uint64_t GasPerByte = Rev < EVMC_SPURIOUS_DRAGON
? zen::evm::EXP_BYTE_GAS_PRE_SPURIOUS_DRAGON
: zen::evm::EXP_BYTE_GAS;
Instance->chargeGas(ExponentByteSize * GasPerByte);

// EVM: (Base ^ Exponent) % (2^256)
intx::uint256 Result = 1;
intx::uint256 CurrentBase = Base;
intx::uint256 ExponentCopy = Exponent;

while (ExponentCopy > 0) {
if (ExponentCopy & 1) {
Result *= CurrentBase;
}
CurrentBase *= CurrentBase;
ExponentCopy >>= 1;
}

return storeUint256Result(Result);
return storeUint256Result(intx::exp(Base, Exponent));
}

const uint8_t *evmGetAddress(zen::runtime::EVMInstance *Instance) {
Expand Down Expand Up @@ -676,6 +661,10 @@ static void evmEmitLogGeneric(zen::runtime::EVMInstance *Instance,
if (!Instance->expandMemoryChecked(Offset, Size)) {
return;
}
const uint64_t LogDataCost = 8 * Size;
if (LogDataCost != 0) {
Instance->chargeGas(LogDataCost);
}
Comment on lines +665 to +667

Copilot AI Jan 22, 2026

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The conditional check for LogDataCost != 0 before charging gas is unnecessary. Similar to the EXP opcode issue, when Size is 0, LogDataCost will be 0, and chargeGas with 0 is safe. This check is inconsistent with the interpreter implementation in opcode_handlers.cpp (line 1511) which doesn't have this conditional. Remove the conditional to maintain consistency.

Suggested change
if (LogDataCost != 0) {
Instance->chargeGas(LogDataCost);
}
Instance->chargeGas(LogDataCost);

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uint8_t *MemoryBase = Instance->getMemoryBase();
Data = MemoryBase + Offset;
}
Expand Down
2 changes: 1 addition & 1 deletion src/evm/opcode_handlers.cpp
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Expand Up @@ -88,10 +88,10 @@ DEFINE_CALCULATE_GAS(Slt, OP_SLT);
DEFINE_CALCULATE_GAS(Sgt, OP_SGT);

// Arithmetic operations
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(Exp, OP_EXP);
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(SignExtend, OP_SIGNEXTEND);
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(Byte, OP_BYTE);
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(Sar, OP_SAR);
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(Exp, OP_EXP);

// Environmental information
DEFINE_NOT_TEMPLATE_CALCULATE_GAS(Address, OP_ADDRESS);
Expand Down
2 changes: 1 addition & 1 deletion src/tests/evm_state_tests.cpp
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Expand Up @@ -18,7 +18,7 @@ namespace {
constexpr bool DEBUG = true;
constexpr bool PRINT_FAILURE_DETAILS = true;
// TODO: RunMode selection logic will be refactored in the future.
constexpr auto STATE_TEST_RUN_MODE = common::RunMode::InterpMode;
constexpr auto STATE_TEST_RUN_MODE = common::RunMode::MultipassMode;

struct TxIntrinsicCost {
int64_t Intrinsic = 0;
Expand Down
8 changes: 5 additions & 3 deletions src/tests/evm_test_helpers.cpp
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Expand Up @@ -39,15 +39,17 @@ calculateLogsHashImpl(const std::vector<evmc::MockedHost::log_record> &Logs) {
std::vector<uint8_t> TopicBytes(Topic.bytes, Topic.bytes + 32);
TopicsEncoded.push_back(zen::evm::rlp::encodeString(TopicBytes));
}
LogComponents.push_back(zen::evm::rlp::encodeList(TopicsEncoded));
LogComponents.push_back(
zen::evm::rlp::encodeListFromEncodedItems(TopicsEncoded));

std::vector<uint8_t> DataBytes(Log.data.begin(), Log.data.end());
LogComponents.push_back(zen::evm::rlp::encodeString(DataBytes));

EncodedLogs.push_back(zen::evm::rlp::encodeList(LogComponents));
EncodedLogs.push_back(
zen::evm::rlp::encodeListFromEncodedItems(LogComponents));
}

auto RlpEncodedLogs = zen::evm::rlp::encodeList(EncodedLogs);
auto RlpEncodedLogs = zen::evm::rlp::encodeListFromEncodedItems(EncodedLogs);

auto Hash = zen::host::evm::crypto::keccak256(RlpEncodedLogs);

Expand Down
12 changes: 12 additions & 0 deletions src/utils/rlp_encoding.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,4 +56,16 @@ encodeList(const std::vector<std::vector<uint8_t>> &Items) {
return LengthBytes;
}

std::vector<uint8_t>
encodeListFromEncodedItems(const std::vector<std::vector<uint8_t>> &Items) {
std::vector<uint8_t> Payload;
for (const auto &Item : Items) {
Payload.insert(Payload.end(), Item.begin(), Item.end());
}

auto LengthBytes = encodeLength(Payload.size(), RLP_OFFSET_SHORT_LIST);
LengthBytes.insert(LengthBytes.end(), Payload.begin(), Payload.end());
return LengthBytes;
}
Comment on lines +59 to +69

Copilot AI Jan 22, 2026

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The new function encodeListFromEncodedItems lacks documentation explaining its purpose and how it differs from encodeList. Add a comment explaining that this function is for encoding a list of items that are already RLP-encoded, whereas encodeList expects raw byte vectors that need to be encoded as strings first.

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} // namespace zen::evm::rlp
2 changes: 2 additions & 0 deletions src/utils/rlp_encoding.h
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Expand Up @@ -18,6 +18,8 @@ extern const uint8_t RLP_OFFSET_SHORT_LIST;
std::vector<uint8_t> encodeLength(size_t Length, uint8_t Offset);
std::vector<uint8_t> encodeString(const std::vector<uint8_t> &Input);
std::vector<uint8_t> encodeList(const std::vector<std::vector<uint8_t>> &Items);
std::vector<uint8_t>
encodeListFromEncodedItems(const std::vector<std::vector<uint8_t>> &Items);

} // namespace zen::evm::rlp

Expand Down
48 changes: 48 additions & 0 deletions tests/evm_spec_test/state_tests/frontier/opcodes/test_exp.py
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@@ -0,0 +1,48 @@
"""
Test EXP opcode.
"""

import pytest
from execution_testing import (
Alloc,
Fork,
Op,
StateTestFiller,
gas_test,
)

REFERENCE_SPEC_GIT_PATH = "N/A"
REFERENCE_SPEC_VERSION = "N/A"
Comment on lines +14 to +15

Copilot AI Jan 22, 2026

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The REFERENCE_SPEC_GIT_PATH should be set to a proper reference instead of "N/A". For the EXP opcode dynamic gas cost, this should reference "EIPS/eip-160.md" as the EXP opcode's dynamic gas cost (50 gas per byte of exponent) was defined in EIP-160.

Suggested change
REFERENCE_SPEC_GIT_PATH = "N/A"
REFERENCE_SPEC_VERSION = "N/A"
REFERENCE_SPEC_GIT_PATH = "EIPS/eip-160.md"
REFERENCE_SPEC_VERSION = "EIP-160"

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@pytest.mark.valid_from("Berlin")
@pytest.mark.parametrize(
"a", [0, 1, pytest.param(2**256 - 1, id="a2to256minus1")]
)
@pytest.mark.parametrize(
"exponent",
[
0,
1,
2,
1023,
1024,
pytest.param(2**255, id="exponent2to255"),
pytest.param(2**256 - 1, id="exponent2to256minus1"),
],
)
def test_gas(
state_test: StateTestFiller,
pre: Alloc,
a: int,
exponent: int,
fork: Fork,
) -> None:
"""Test that EXP gas works as expected."""
gas_test(
fork=fork,
state_test=state_test,
pre=pre,
setup_code=Op.PUSH32(exponent) + Op.PUSH32(a),
Comment on lines +20 to +46

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The parameter name "a" is ambiguous. It should be renamed to "base" to match the EXP opcode semantics where EXP takes two operands: base and exponent. This would make the test more readable and align with the variable names used in the implementation (Base and Exponent in opcode_handlers.cpp line 316-317).

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subject_code=Op.EXP(exponent=exponent),
)
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