fix: charge dynamic gas for EXP and LOG in multipass,align log hashing by ZR74 · Pull Request #278 · DTVMStack/DTVM

ZR74 · 2026-01-22T10:19:49Z

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

N
Y

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

Affects user behaviors
Contains CI/CD configuration changes
Contains documentation changes
Contains experimental features
Performance regression: Consumes more CPU
Performance regression: Consumes more Memory
Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

N
Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

6. Release note

None

Copilot

Pull request overview

This PR fixes dynamic gas charging for the EXP and LOG opcodes in multipass/compiler mode and corrects a log hashing bug in the RLP encoding.

Changes:

Implements dynamic gas charging for EXP opcode (50 gas per byte of exponent, per EIP-160) in both interpreter and multipass modes
Implements dynamic gas charging for LOG opcodes (8 gas per byte of log data) in multipass mode
Fixes RLP encoding double-encoding bug by introducing encodeListFromEncodedItems function for already-encoded items
Adds comprehensive gas cost test coverage for EXP and LOG opcodes
Switches state test run mode from InterpMode to MultipassMode

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
`src/evm/opcode_handlers.h`	Moves EXP from simple binary operation to custom handler with dynamic gas calculation
`src/evm/opcode_handlers.cpp`	Implements EXP handler with byte-size-based dynamic gas charging
`src/compiler/evm_frontend/evm_imported.cpp`	Adds dynamic gas charging for EXP (exponent byte size) and LOG (data size) in multipass mode
`src/utils/rlp_encoding.h`	Declares new `encodeListFromEncodedItems` function for RLP encoding
`src/utils/rlp_encoding.cpp`	Implements `encodeListFromEncodedItems` to handle already-encoded items without double-encoding
`src/tests/evm_test_helpers.cpp`	Uses `encodeListFromEncodedItems` to fix log hash calculation bug
`src/tests/evm_state_tests.cpp`	Changes test run mode from InterpMode to MultipassMode
`tests/evm_spec_test/state_tests/frontier/opcodes/test_exp.py`	Adds comprehensive gas cost tests for EXP opcode
`tests/evm_spec_test/state_tests/frontier/opcodes/test_log.py`	Adds comprehensive gas cost tests for LOG opcodes

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Copilot · 2026-01-22T10:26:02Z

+  if (ExponentByteSize > 0) {
+    static constexpr uint64_t GasPerByte = 50;
+    Instance->chargeGas(ExponentByteSize * GasPerByte);
+  }


The conditional check for ExponentByteSize > 0 before charging gas is unnecessary and inconsistent with the interpreter implementation. According to EIP-160, the EXP opcode should charge dynamic gas based on the byte size of the exponent, and when the exponent is 0, the byte size is 0, resulting in 0 dynamic gas being charged. The chargeGas call with 0 is safe and keeps both implementations consistent. Remove the conditional check and always call chargeGas to match the interpreter behavior in opcode_handlers.cpp.

Suggested change

if (ExponentByteSize > 0) {

static constexpr uint64_t GasPerByte = 50;

Instance->chargeGas(ExponentByteSize * GasPerByte);

}

static constexpr uint64_t GasPerByte = 50;

Instance->chargeGas(ExponentByteSize * GasPerByte);

Copilot · 2026-01-22T10:26:03Z

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


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);

Copilot · 2026-01-22T10:26:03Z

+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;
+}


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.

Copilot · 2026-01-22T10:26:03Z

+REFERENCE_SPEC_GIT_PATH = "N/A"
+REFERENCE_SPEC_VERSION = "N/A"


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"

Copilot · 2026-01-22T10:26:04Z

+    "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),


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).

DTVMStack#278)

Copilot AI review requested due to automatic review settings January 22, 2026 10:19

Copilot started reviewing on behalf of ZR74 January 22, 2026 10:20 View session

Copilot AI reviewed Jan 22, 2026

View reviewed changes

ZR74 force-pushed the pr-state-test branch from 8144ebb to 6974937 Compare January 26, 2026 08:08

ZR74 added 4 commits January 26, 2026 17:13

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

f1aa7ac

style: format check

f50b449

fix: exclude CALL stipend from callee gas charge

f98db55

fix: align exp behavior with interpreter

b5246ec

ZR74 force-pushed the pr-state-test branch from 6974937 to b5246ec Compare January 26, 2026 09:48

zoowii merged commit ddff9e6 into DTVMStack:main Jan 28, 2026
10 checks passed

ZR74 deleted the pr-state-test branch January 28, 2026 12:13

abmcar pushed a commit to abmcar/DTVM that referenced this pull request Feb 2, 2026

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

97b52e3

DTVMStack#278)

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

fix: charge dynamic gas for EXP and LOG in multipass,align log hashing#278
zoowii merged 4 commits into
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ZR74:pr-state-test

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		REFERENCE_SPEC_GIT_PATH = "N/A"
		REFERENCE_SPEC_VERSION = "N/A"

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ZR74 commented Jan 22, 2026

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

6. Release note

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