Add contracts for HostIO gas tests

These contracts will be used by the nitro tests that check the
equivalence between stylus and EVM.

Co-authored-by: Aman Sanghi <asanghi@offchainlabs.com>

hardhat.config.ts

@@ -34,6 +34,16 @@ const solidity = {
         },
       },
     },
+    'src/mocks/HostioTest.sol': {
+      version: '0.8.24',
+      settings: {
+        optimizer: {
+          enabled: true,
+          runs: 100,
+        },
+        evmVersion: 'cancun',
+      },
+    },
   },
 }
 

src/mocks/CreateTest.sol

@@ -0,0 +1,42 @@
+// Copyright 2024, Offchain Labs, Inc.
+// For license information, see https://github.com/nitro/blob/master/LICENSE
+// SPDX-License-Identifier: BUSL-1.1
+
+pragma solidity ^0.8.0;
+
+/*
+ * This contract is the solidity equivalent of the stylus create test contract.
+ */
+contract CreateTest {
+    // solhint-disable no-complex-fallback
+    // solhint-disable reason-string
+    // solhint-disable avoid-low-level-calls
+    // solhint-disable-next-line prettier/prettier
+    fallback(bytes calldata input) external returns (bytes memory) {
+        uint8 kind = uint8(input[0]);
+        input = input[1:];
+
+        bytes32 endowment = bytes32(input[:32]);
+        input = input[32:];
+
+        address addr;
+
+        if (kind == 2) {
+            bytes32 salt = bytes32(input[:32]);
+            input = input[32:];
+            bytes memory code = input;
+            assembly {
+                addr := create2(endowment, add(code, 32), mload(code), salt)
+            }
+        } else {
+            bytes memory code = input;
+            assembly {
+                addr := create(endowment, add(code, 32), mload(code))
+            }
+        }
+        if (addr == address(0)) {
+            revert("failed to create");
+        }
+        return addr.code;
+    }
+}

src/mocks/HostioTest.sol

@@ -0,0 +1,189 @@
+// Copyright 2024, Offchain Labs, Inc.
+// For license information, see https://github.com/nitro/blob/master/LICENSE
+// SPDX-License-Identifier: BUSL-1.1
+
+pragma solidity ^0.8.24;
+
+/*
+ * HostioTest is a test contract used to compare EVM with Stylus.
+ */
+contract HostioTest {
+    function exitEarly() external pure {
+        assembly {
+            stop()
+        }
+    }
+
+    function transientLoadBytes32(bytes32 key) external view returns (bytes32) {
+        bytes32 data;
+        assembly {
+            data := tload(key)
+        }
+        return data;
+    }
+
+    function transientStoreBytes32(bytes32 key, bytes32 value) external {
+        assembly {
+            // solc-ignore-next-line transient-storage
+            tstore(key, value)
+        }
+    }
+
+    function returnDataSize() external pure returns (uint256) {
+        uint256 size;
+        assembly {
+            size := returndatasize()
+        }
+        return size;
+    }
+
+    function emitLog(
+        bytes calldata _data,
+        int8 n,
+        bytes32 t1,
+        bytes32 t2,
+        bytes32 t3,
+        bytes32 t4
+    ) external {
+        bytes memory data = _data;
+        if (n == 0) {
+            assembly {
+                log0(add(data, 32), mload(data))
+            }
+        } else if (n == 1) {
+            assembly {
+                log1(add(data, 32), mload(data), t1)
+            }
+        } else if (n == 2) {
+            assembly {
+                log2(add(data, 32), mload(data), t1, t2)
+            }
+        } else if (n == 3) {
+            assembly {
+                log3(add(data, 32), mload(data), t1, t2, t3)
+            }
+        } else if (n == 4) {
+            assembly {
+                log4(add(data, 32), mload(data), t1, t2, t3, t4)
+            }
+        } else {
+            revert("invalid n for emit log");
+        }
+    }
+
+    function accountBalance(address account) external view returns (uint256) {
+        return account.balance;
+    }
+
+    function accountCode(address account) external view returns (bytes memory) {
+        return account.code;
+    }
+
+    function accountCodeSize(address account) external view returns (uint256) {
+        uint256 size;
+        assembly {
+            size := extcodesize(account)
+        }
+        return size;
+    }
+
+    function accountCodehash(address account) external view returns (bytes32) {
+        bytes32 hash;
+        assembly {
+            hash := extcodehash(account)
+        }
+        return hash;
+    }
+
+    function evmGasLeft() external view returns (uint256) {
+        return gasleft();
+    }
+
+    function evmInkLeft() external view returns (uint256) {
+        return gasleft();
+    }
+
+    function blockBasefee() external view returns (uint256) {
+        return block.basefee;
+    }
+
+    function chainid() external view returns (uint256) {
+        return block.chainid;
+    }
+
+    function blockCoinbase() external view returns (address) {
+        return block.coinbase;
+    }
+
+    function blockGasLimit() external view returns (uint256) {
+        return block.gaslimit;
+    }
+
+    function blockNumber() external view returns (uint256) {
+        return block.number;
+    }
+
+    function blockTimestamp() external view returns (uint256) {
+        return block.timestamp;
+    }
+
+    function contractAddress() external view returns (address) {
+        return address(this);
+    }
+
+    function mathDiv(uint256 a, uint256 b) external pure returns (uint256) {
+        return a / b;
+    }
+
+    function mathMod(uint256 a, uint256 b) external pure returns (uint256) {
+        return a % b;
+    }
+
+    function mathPow(uint256 a, uint256 b) external pure returns (uint256) {
+        uint256 result;
+        assembly {
+            result := exp(a, b)
+        }
+        return result;
+    }
+
+    function mathAddMod(
+        uint256 a,
+        uint256 b,
+        uint256 c
+    ) external pure returns (uint256) {
+        return addmod(a, b, c);
+    }
+
+    function mathMulMod(
+        uint256 a,
+        uint256 b,
+        uint256 c
+    ) external pure returns (uint256) {
+        return mulmod(a, b, c);
+    }
+
+    function msgSender() external view returns (address) {
+        return msg.sender;
+    }
+
+    function msgValue() external payable returns (uint256) {
+        return msg.value;
+    }
+
+    function keccak(bytes calldata preimage) external pure returns (bytes32) {
+        return keccak256(preimage);
+    }
+
+    function txGasPrice() external view returns (uint256) {
+        return tx.gasprice;
+    }
+
+    function txInkPrice() external view returns (uint256) {
+        return tx.gasprice;
+    }
+
+    function txOrigin() external view returns (address) {
+        return tx.origin;
+    }
+}