feat(ctb): make MIPS oracle addrs immutable

cannon/mipsevm/evm.go

@@ -112,9 +112,17 @@ func NewEVMEnv(contracts *Contracts, addrs *Addresses) (*vm.EVM, *state.StateDB)
 
 	env := vm.NewEVM(blockContext, vm.TxContext{}, state, chainCfg, vmCfg)
 	// pre-deploy the contracts
-	env.StateDB.SetCode(addrs.MIPS, contracts.MIPS.DeployedBytecode.Object)
 	env.StateDB.SetCode(addrs.Oracle, contracts.Oracle.DeployedBytecode.Object)
-	env.StateDB.SetState(addrs.MIPS, common.Hash{}, addrs.Oracle.Hash())
+
+	var mipsCtorArgs [32]byte
+	copy(mipsCtorArgs[12:], addrs.Oracle[:])
+	mipsDeploy := append(hexutil.MustDecode(bindings.MIPSMetaData.Bin), mipsCtorArgs[:]...)
+	startingGas := uint64(30_000_000)
+	_, deployedMipsAddr, leftOverGas, err := env.Create(vm.AccountRef(addrs.Sender), mipsDeploy, startingGas, big.NewInt(0))
+	if err != nil {
+		panic(fmt.Errorf("failed to deploy MIPS contract: %w. took %d gas", err, startingGas-leftOverGas))
+	}
+	addrs.MIPS = deployedMipsAddr
 
 	rules := env.ChainConfig().Rules(header.Number, true, header.Time)
 	env.StateDB.Prepare(rules, addrs.Sender, addrs.FeeRecipient, &addrs.MIPS, vm.ActivePrecompiles(rules), nil)

packages/contracts-bedrock/src/cannon/MIPS.sol

@@ -53,11 +53,15 @@ contract MIPS {
     uint32 constant EINVAL = 0x16;
 
     /// @notice The preimage oracle contract.
-    IPreimageOracle public oracle;
+    IPreimageOracle internal immutable ORACLE;
 
     /// @param _oracle The address of the preimage oracle contract.
     constructor(IPreimageOracle _oracle) {
-        oracle = _oracle;
+        ORACLE = _oracle;
+    }
+
+    function oracle() external view returns (IPreimageOracle oracle_) {
+        oracle_ = ORACLE;
     }
 
     /// @notice Extends the value leftwards with its most significant bit (sign extension).
@@ -179,7 +183,7 @@ contract MIPS {
                     if (uint8(preimageKey[0]) == 1) {
                         preimageKey = PreimageKeyLib.localize(preimageKey);
                     }
-                    (bytes32 dat, uint256 datLen) = oracle.readPreimage(preimageKey, state.preimageOffset);
+                    (bytes32 dat, uint256 datLen) = ORACLE.readPreimage(preimageKey, state.preimageOffset);
 
                     // Transform data for writing to memory
                     // We use assembly for more precise ops, and no var count limit