PVM: Matter Labs revert tests fail with Out Of Gas (resolc 0.6.0)

[marian-radu]

The tests started failing after updating resolc from 0.5.0 to 0.6.0, likely due to changes in PR #443

A list of the newly failing tests can be found here

The tests that fail with OOG seem to have in common that the len parameter exceeds the 32-bit integer range.
According to the following note from the revive compiler book, the contract is expected to trap. Should it also consume all gas?

Many functions receive memory buffer offset pointer or size arguments. Since the PVM pointer size is 32 bit, supplying memory offset or buffer size values above 2^32-1 will trap the contract immediately.

[marian-radu]

A simplified contract to reproduce the issue:

//! {
//!   "cases": [
//!     {
//!       "name": "fail",
//!       "inputs": [
//!         {
//!           "method": "test",
//!           "calldata": [
//!             "0",
//!             "0x100000000"
//!           ],
//!           "caller": "0x68fad4309f97dc1847e3dd28eb9a464b89dbb420"
//!         }
//!       ],
//!       "expected": [
//!         "0x00000000000000000000000000000000000000000000000000000000deadbeef"
//!       ]
//!     },
//!     {
//!       "name": "success",
//!       "inputs": [
//!         {
//!           "method": "test",
//!           "calldata": [
//!             "0",
//!             "0xFFFFFFFF"
//!           ],
//!           "caller": "0x68fad4309f97dc1847e3dd28eb9a464b89dbb420"
//!         }
//!       ],
//!       "expected": [
//!         "0x00000000000000000000000000000000000000000000000000000000deadbeef"
//!       ]
//!     }
//!   ]
//! }

// SPDX-License-Identifier: MIT

pragma solidity >=0.4.21;
pragma solidity >=0.4.21;

contract Test {
    function test(uint256 offset, uint256 len) external {
        assembly {
            mstore(0, 0xcc572cf9) // main selector
            mstore(32, offset)
            mstore(64, len)
            let success := call(gas(), address(), 0, 28, 68, 0, 0)
            mstore(0, 0xdeadbeef)
            return(0, 32)
        }
    }

    function main(uint256 offset, uint256 len) external pure {
        assembly {
            // nullify memory ptr slot
            mstore(0x40, 0)
            revert(offset, len)
        }
    }
}

[xermicus]

TL;DR of what's going:

• We (deliberately) don't have the 63/64 rule implemented in the pallet
• The contract forwards all gas
• With the newest compiler version, the child contract code fails its bounds checks and hits consume_all_gas, leading to the whole TX running out of gas (with earlier compiler versions the contract was just trapping)
• Thus the observed return value is different because the caller has no gas left to set the expected return value.

The docs are not fully correct anymore. Thanks for pointing this out! This PR adds this as a test case and updates the docs.

Do the test work after updating the fixtures accordingly? If not, there is something additional we are missing here.