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towards a standard EVM trace format

See original GitHub issue

Towards a standard EVM trace format

The purpose of this standard trace format is to facilitate automated equivalence testing of different EVM implementations.

steps are logged with the state of the environment (stack, gas remaining, program counter, etc.) immediately before execution of the opcode.
call stack depth starts at zero

Temporary workarounds

steps that result in exceptions (e.g. OOG exceptions) are logged as if they were successful
- except for invalid opcode exceptions, which are not logged
  - invalid opcode exception is easy to check for before execution
  - it is easier to remove them from the log than to converge on a standard error code
- it is useful to see in a trace the operation that caused an OOG exception, or a stack underflow, etc.
- but it complicates the tracing logic if the result of an operation needs to be known before it is logged

Noted quirks

geth logs STOP operations on all successful exits, even when there is no STOP opcode. For example, where pyethereum logs:

TRACE:eth.vm.op	{"event": "eth.vm.op.vm", "level": "TRACE", "op": "SSTORE", "stack": ["b'133001'", "b'2'"], "gas": "b'20030'", "inst": 85, "pc": "b'72'", "steps": 32, "depth": 132}
TRACE:eth.vm.exit {"event": "eth.vm.exit.exit", "level": "TRACE", "cause": "CODE OUT OF RANGE"}

geth will log:

{"pc":72,"op":85,"gas":"0x4e3e","gasCost":"0x4e20","memory":"0x","memSize":0,"stack":["0x20789","0x2"],"depth":133,"error":null,"opName":"SSTORE"}
{"pc":73,"op":0,"gas":"0x1e","gasCost":"0x0","memory":"0x","memSize":0,"stack":[],"depth":133,"error":null,"opName":"STOP"}

Example trace

This trace is produced by executing the stCallCodes/callcall_00 state test.

{'pc': 0, 'op': 96, 'gas': '0x2d74b8', 'gasCost': '0x3', 'stack': [], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 2, 'op': 96, 'gas': '0x2d74b5', 'gasCost': '0x3', 'stack': ['0x40'], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 4, 'op': 96, 'gas': '0x2d74b2', 'gasCost': '0x3', 'stack': ['0x40', '0x0'], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 6, 'op': 96, 'gas': '0x2d74af', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40'], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 8, 'op': 96, 'gas': '0x2d74ac', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0'], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 10, 'op': 115, 'gas': '0x2d74a9', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x1'], 'depth': 0, 'opName': 'PUSH20'}
{'pc': 31, 'op': 98, 'gas': '0x2d74a6', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x1', '0x1000000000000000000000000000000000000001'], 'depth': 0, 'opName': 'PUSH3'}
{'pc': 35, 'op': 241, 'gas': '0x2d74a3', 'gasCost': '0x57d1a', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x1', '0x1000000000000000000000000000000000000001', '0x55730'], 'depth': 0, 'opName': 'CALL'}
{'pc': 0, 'op': 96, 'gas': '0x5602c', 'gasCost': '0x3', 'stack': [], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 2, 'op': 96, 'gas': '0x56029', 'gasCost': '0x3', 'stack': ['0x40'], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 4, 'op': 96, 'gas': '0x56026', 'gasCost': '0x3', 'stack': ['0x40', '0x0'], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 6, 'op': 96, 'gas': '0x56023', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40'], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 8, 'op': 96, 'gas': '0x56020', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0'], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 10, 'op': 115, 'gas': '0x5601d', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x2'], 'depth': 1, 'opName': 'PUSH20'}
{'pc': 31, 'op': 98, 'gas': '0x5601a', 'gasCost': '0x3', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x2', '0x1000000000000000000000000000000000000002'], 'depth': 1, 'opName': 'PUSH3'}
{'pc': 35, 'op': 241, 'gas': '0x56017', 'gasCost': '0x3f67a', 'stack': ['0x40', '0x0', '0x40', '0x0', '0x2', '0x1000000000000000000000000000000000000002', '0x3d090'], 'depth': 1, 'opName': 'CALL'}
{'pc': 0, 'op': 96, 'gas': '0x3d98c', 'gasCost': '0x3', 'stack': [], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 2, 'op': 96, 'gas': '0x3d989', 'gasCost': '0x3', 'stack': ['0x1'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 4, 'op': 85, 'gas': '0x3d986', 'gasCost': '0x4e20', 'stack': ['0x1', '0x2'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 5, 'op': 51, 'gas': '0x38b66', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'CALLER'}
{'pc': 6, 'op': 96, 'gas': '0x38b64', 'gasCost': '0x3', 'stack': ['0x1000000000000000000000000000000000000001'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 8, 'op': 85, 'gas': '0x38b61', 'gasCost': '0x4e20', 'stack': ['0x1000000000000000000000000000000000000001', '0x4'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 9, 'op': 52, 'gas': '0x33d41', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'CALLVALUE'}
{'pc': 10, 'op': 96, 'gas': '0x33d3f', 'gasCost': '0x3', 'stack': ['0x2'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 12, 'op': 85, 'gas': '0x33d3c', 'gasCost': '0x4e20', 'stack': ['0x2', '0x7'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 13, 'op': 48, 'gas': '0x2ef1c', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'ADDRESS'}
{'pc': 14, 'op': 96, 'gas': '0x2ef1a', 'gasCost': '0x3', 'stack': ['0x1000000000000000000000000000000000000002'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 16, 'op': 85, 'gas': '0x2ef17', 'gasCost': '0x4e20', 'stack': ['0x1000000000000000000000000000000000000002', '0xe6'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 17, 'op': 50, 'gas': '0x2a0f7', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'ORIGIN'}
{'pc': 18, 'op': 96, 'gas': '0x2a0f5', 'gasCost': '0x3', 'stack': ['0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 20, 'op': 85, 'gas': '0x2a0f2', 'gasCost': '0x4e20', 'stack': ['0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b', '0xe8'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 21, 'op': 54, 'gas': '0x252d2', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'CALLDATASIZE'}
{'pc': 22, 'op': 96, 'gas': '0x252d0', 'gasCost': '0x3', 'stack': ['0x40'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 24, 'op': 85, 'gas': '0x252cd', 'gasCost': '0x4e20', 'stack': ['0x40', '0xec'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 25, 'op': 56, 'gas': '0x204ad', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'CODESIZE'}
{'pc': 26, 'op': 96, 'gas': '0x204ab', 'gasCost': '0x3', 'stack': ['0x21'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 28, 'op': 85, 'gas': '0x204a8', 'gasCost': '0x4e20', 'stack': ['0x21', '0xee'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 29, 'op': 58, 'gas': '0x1b688', 'gasCost': '0x2', 'stack': [], 'depth': 2, 'opName': 'GASPRICE'}
{'pc': 30, 'op': 96, 'gas': '0x1b686', 'gasCost': '0x3', 'stack': ['0x1'], 'depth': 2, 'opName': 'PUSH1'}
{'pc': 32, 'op': 85, 'gas': '0x1b683', 'gasCost': '0x4e20', 'stack': ['0x1', '0xf0'], 'depth': 2, 'opName': 'SSTORE'}
{'pc': 36, 'op': 96, 'gas': '0x2d200', 'gasCost': '0x3', 'stack': ['0x1'], 'depth': 1, 'opName': 'PUSH1'}
{'pc': 38, 'op': 85, 'gas': '0x2d1fd', 'gasCost': '0x4e20', 'stack': ['0x1', '0x1'], 'depth': 1, 'opName': 'SSTORE'}
{'pc': 36, 'op': 96, 'gas': '0x2a7b66', 'gasCost': '0x3', 'stack': ['0x1'], 'depth': 0, 'opName': 'PUSH1'}
{'pc': 38, 'op': 85, 'gas': '0x2a7b63', 'gasCost': '0x4e20', 'stack': ['0x1', '0x0'], 'depth': 0, 'opName': 'SSTORE'}
{"output":"","gasUsed":"0x34775","time":1967173}

Issue Analytics

State:
Created 6 years ago
Reactions:3
Comments:37 (29 by maintainers)

Top GitHub Comments

1reaction

chfastcommented, May 11, 2018

@cdetrio @holiman I’m back to this issue because I want finally to implement this in EVMC.

I still believe it would be more convenient to report the effect of the instruction execution, not the state before the execution. In this case it might be enough to only report the top stack item being the result of the execution of the current opcode. Also the cost of the execution and exceptions can be reported.

0reactions

winsvegacommented, Nov 26, 2022

Currently geths evm trace is a standard. Just run tests with --vmtraceraw on geth to see the format

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