feature request: rpc method for per opcode gas tracing

[sslivkoff]

Describe the feature

It would be very nice to have an rpc method ("opcode_trace") that gives a per-transaction accounting of:

• how many times each opcode was called
• how much total gas was used per opcode

This would be the final missing piece for full resolution gas analysis.

Data could have a similar schema to state_diffs tracing:

data = {
    "opcode": [
        {
            "transaction_hash": "0x1234...",
            "opcode_counts": {
                "SSTORE": 17,
                ...
            },
            "opcode_gas": {
                "SSTORE": 153000,
                ...
            },
            ...
        }
        {
            "transaction_hash": "0x8764...",
            ...
        }
    ]
}

Additional context

No response

[gakonst]

I think this should be possible via a custom tracer similar to Geth's tracers, or should this be in a separate trace method @mattsse ?

[mattsse]

I believe the only way to do this rn is via JS

but it's possible to add this

[github-actions]

This issue is stale because it has been open for 21 days with no activity.

[mattsse]

cc @DoTheBestToGetTheBest

we can add this as trace_blockOpcodeGas and trace_transactionOpcodeGas

[sslivkoff]

[edited for future-proofness, turned opcodes into list not map]

possible schema for output

1. trace_transactionOpcodeGas

request:
[txHash]

response:

{
    "transactionHash": "0xb5be..."
    "opcodes": [
        {"opcode": "SSTORE", "count": 4, "gas_used": 38000},
        {"opcode": "CREATE", "count": 1, "gas_used": 32000},
        ...
    ],
}

2. trace_blockOpcodeGas

request:
[blockNumber | blockHash]

response:

{
    "blockHash": "0x9eaf...",
    "transactions": [trace_transactionOpcodeGasResponse],
}