Wrong gas estimation in contract calling another contract

[crystalin]

Description

The estimate Gas is (very) wrong when computing the needed gas when a contract calls another contract

Steps to Reproduce

Using those contract:

pragma solidity ^0.7.0;
contract Caller {
    Callee internal callee;
    uint public store;
    function someAction(address _addr, uint _number) public {
        callee = Callee(_addr);
        store = callee.addtwo(_number);
    }
}
contract Callee {
    function addtwo(uint _value) external pure returns (uint) {
        return _value + 2;
    }
}

Steps:

1. Deploy Callee (fetch address)
2. Deploy Caller
3. Run someAction by passing Callee's address and a number. It will execute the function addtwo from the other contract

Expected vs. Actual Behavior

It returns 67M gas which is way over a normal expected value.

Logs, Errors or Screenshots

Additional Information

[jnaviask]

I believe that's what this PR was intended to fix: #269 -- try building with feature rpc_binary_search_estimate and see if it still gets it wrong.

[crystalin]

Thank you @jnaviask , I thought we had this one already included but is not. I'll double check once merged on our branch

[albertov19]

@jnaviask that fixed the issue in way - but we ran into another problem that just stalled the EVM. So the gas estimation problem still persists.

Logs from the evm trace when the problem happened:

2021-02-11 18:25:00.192  DEBUG        http.worker00 evm: Call execution using address 0x42e2…c741: Revert(Reverted)    
2021-02-11 18:25:00.192  DEBUG        http.worker00 evm: Execution Revert(Reverted) [source: 0x6be02d1d3665660d22ff9624b7be0551ee1ac91b, value: 0, gas_limit: 1000000000, actual_fee: 0]    
2021-02-11 18:25:00.268  DEBUG        http.worker00 evm: Call execution using address 0x42e2…c741: Revert(Reverted)    
2021-02-11 18:25:00.268  DEBUG        http.worker00 evm: Execution Revert(Reverted) [source: 0x6be02d1d3665660d22ff9624b7be0551ee1ac91b, value: 0, gas_limit: 1000000000, actual_fee: 0]    
2021-02-11 18:25:00.348  DEBUG        http.worker00 evm: Call execution using address 0x42e2…c741: Revert(Reverted) 

[notlesh]

This issue is likely related: rust-ethereum/evm#8

[jnaviask]

@jnaviask that fixed the issue in way - but we ran into another problem that just stalled the EVM. So the gas estimation problem still persists.

@albertov19 What can I do to reproduce this? Did it happen with the original contract @crystalin posted?

[albertov19]

@jnaviask No, it was with a more complex contract when deploying Uniswap V2. When swapping tokens. I don't a step by step way of explaining how to reproduce right now but in short:

• Deploy Uniswap V2 Factory
• Deploy WETH
• Deploy Uniswap Router V2
• Deploy 2 ERC20 Tokens (or 1 token and use WETH as the other)
• Add Liquidity
• Swap tokens (ERROR)

[notlesh]

@jnaviask that fixed the issue in way - but we ran into another problem that just stalled the EVM. So the gas estimation problem still persists.

@albertov19 What can I do to reproduce this? Did it happen with the original contract @crystalin posted?

Edit: Sorry, I had the wrong context when I originally wrote this. The binary search approach seems to work for this trivial contract, but fails on the complex contract as @albertov19 mentioned. The rest of this applies to reproducing the original bug (without binary search enabled).

We have a PR on Moonbeam with an integration test that currently fails over this issue:

moonbeam-foundation/moonbeam#244

Reproducing it in this way should be as simple as:

1. Build our repo (cargo build --release --all)
2. Prepare test environment (cd moonbeam-types-bundle && npm install && cd ../tests && npm install)
3. Run test (npm run test -- --grep "Gas Estimation")

[notlesh]

Also note that in this case, the overestimation appears to be roughly equal to:

actual_gas_cost + (original_gas_limit / 64)

This seems to point to the l64() functionality as problematic.

[librelois]

@albertov19 I think the fix #297 should have solved your problem, could you test ? :)

[boundless-forest]

Very old one. Close it.