(Custom EVM tracer): Reported opcode gas cost is incorrect

[raxhvl]

Describe the bug

When using a custom evm tracer, the gas cost for opcoded reported by the tracer is incorrect.

Steps to reproduce

Consider the following debug_traceTransaction RPC reqeust:

import asyncio
import json
import os

from aiohttp import ClientSession, TCPConnector


async def custom_tracer():
    async with ClientSession(connector=TCPConnector(limit=0)) as session:
        method = "debug_traceTransaction"
        tracer = """
        {
            data: [],
            memoryInstructions: {"MSTORE":"W", "MSTORE8":"B", "MLOAD":"R"},
            fault: function (log) {},
            step: function (log) {
                let op = log.op.toString();
                let instructions = this.memoryInstructions
                if (Object.keys(instructions).includes(op)) {
                this.data.push({
                    op: instructions[op] ,
                    depth: log.getDepth(),
                    offset: log.stack.peek(0),
                    gasCost: log.getCost(),
                    memorySize: log.memory.length(),
                });
                }
            },
            result: function (ctx, _) {
                return {
                    error: !!ctx.error,
                    data: this.data
                };
            }
        }
        """
        params = [
            "0x82f6413a2658ebb83f27e44fe1e815ec0979a7dcc0bc9dbdbbbe058d547195a6",
            {"tracer": tracer},
        ]

        payload = {
            "jsonrpc": "2.0",
            "method": method,
            "params": params,
            "id": 1,
        }

        async with session.post(
            "https://lb.nodies.app/v2/8bfbba93396a46b1a3d99311daf0dae6",
            json=payload,
            headers={"x-api-key": "b27881a7-4ea2-439f-a1c6-77ad0c875c16"},
        ) as response:
            result = await response.json()
            if "error" in result:
                raise Exception(f"RPC Error ({method}>req:{params}): {result['error']}")

            with open(os.path.join("trace.json"), "w") as output_file:
                json.dump(result, output_file)
asyncio.run(custom_tracer())

Expected gas costs:

[
  6,  6, 3, 3, 12, 3,  3,  9, 6, 3, 3, 3,
  3,  3, 3, 3,  3, 6,  6,  3, 3, 3, 3, 3,
  3,  3, 3, 3,  3, 3,  3,  3, 3, 6, 6, 3,
  3,  3, 3, 6,  6, 3,  3,  3, 3, 3, 3, 6,
  6,  3, 6, 3,  3, 3,  3, 12, 3, 3, 9, 6,
  3, 12, 6, 3,  3, 3,  3,  3, 3, 3, 3, 6,
  3,  6, 3, 6,  3, 3, 12,  3, 3, 3, 3, 3,
  3,  3, 6, 3,  3, 3,  3,  3, 3, 3, 3, 3,
  3,  3, 3, 3,
  ... 5998 more items
]

Reported gas cost:

[
    138,   150,   229,   317,     6,  2148,  2163,  2175,  2196,
   2642,  2657,  2925,  2940,  3191,  3206,  4376,  4391,  4403,
   4421,  4746,  4761,  4996,  5011,  5284,  5299,  5875,  5890,
   6643,  6658,  7284,  7299,  7493,  7508,  7520,  7538,  7867,
   7882, 10896, 10911, 10923, 10941, 11270, 11285, 11741, 11756,
  14788, 14803, 14815, 14833, 15142, 15256, 15297, 17115, 17235,
  17273,     6,  4184,  4199,  4208,  4232,  4241,  4265,  4295,
   4304,  4328,  4346,  4361,  4379,  4385,  4391,  4465,  4471,
   4547,  4553,  4714,  4726,  4747,  4783,     6,   415,   430,
    697,   712,  3820,  3835,  6943,  6955,  6977,  8804,  8828,
   8847, 13805, 13839, 13847, 13921, 13960, 13991, 14054, 14063,
  14077,
  ... 5998 more items
]

Node logs

No response

Platform(s)

Linux (x86)

What version/commit are you on?

reth Version: 1.0.0-dev
Commit SHA: 4fd06bd3b
Build Timestamp: 2024-07-06T20:32:43.565379262Z
Build Features: jemalloc
Build Profile: maxperf

What database version are you on?

Current database version: 2
Local database is uninitialized

Which chain / network are you on?

mainnet

What type of node are you running?

Archive (default)

What prune config do you use, if any?

No response

If you've built Reth from source, provide the full command you used

No response

Code of Conduct

• I agree to follow the Code of Conduct

[mattsse]

thanks for flagging, the gascost value is indeed set incorrectly