poc: system config address discoverability

Solve the address discoverability by adding getters
on the system config for the L1 proxies. This is
very easy to accomplish, now the user only needs
to know the address of the systemconfig with
a particular op stack chain to know all of the
L1 contract addresses. It makes tracking all
of the chains in the superchain much easier.

There are still some todos for this PR,
a getter needs to be added for each address.

packages/contracts-bedrock/scripts/Deploy.s.sol

@@ -498,9 +498,16 @@ contract Deploy is Deployer {
                     batcherHash,
                     uint64(cfg.l2GenesisBlockGasLimit()),
                     cfg.p2pSequencerAddress(),
-                    Constants.DEFAULT_RESOURCE_CONFIG()
+                    Constants.DEFAULT_RESOURCE_CONFIG(),
+                    mustGetAddress("L1CrossDomainMessengerProxy"),
+                    mustGetAddress("L1ERC721BridgeProxy"),
+                    mustGetAddress("L1StandardBridgeProxy"),
+                    mustGetAddress("L2OutputOracleProxy"),
+                    mustGetAddress("OptimismPortalProxy")
                 )
             )
+
+            // TODO: assert that addresses are correct
         });
 
         SystemConfig config = SystemConfig(systemConfigProxy);

packages/contracts-bedrock/src/L1/SystemConfig.sol

@@ -34,6 +34,12 @@ contract SystemConfig is OwnableUpgradeable, Semver {
     ///         proof to fetch this value.
     bytes32 public constant UNSAFE_BLOCK_SIGNER_SLOT = keccak256("systemconfig.unsafeblocksigner");
 
+    bytes32 public constant L1_CROSS_DOMAIN_MESSENGER_SLOT = keccak256("systemconfig.l1crossdomainmessenger");
+    bytes32 public constant L1_ERC_721_BRIDGE_SLOT = keccak256("systemconfig.l1erc721bridge");
+    bytes32 public constant L1_STANDARD_BRIDGE_SLOT = keccak256("systemconfig.l1standardbridge");
+    bytes32 public constant L2_OUTPUT_ORACLE_SLOT = keccak256("systemconfig.l2outputoracle");
+    bytes32 public constant OPTIMISM_PORTAL_SLOT = keccak256("systemconfig.optimismportal");
+
     /// @notice Fixed L2 gas overhead. Used as part of the L2 fee calculation.
     uint256 public overhead;
 
@@ -59,6 +65,10 @@ contract SystemConfig is OwnableUpgradeable, Semver {
     /// @param data       Encoded update data.
     event ConfigUpdate(uint256 indexed version, UpdateType indexed updateType, bytes data);
 
+    /// @notice The block at which the op-node can start searching for
+    ///         logs from
+    uint256 startBlock;
+
     /// @custom:semver 1.3.1
     /// @notice Constructs the SystemConfig contract.
     /// @param _owner             Initial owner of the contract.
@@ -84,7 +94,12 @@ contract SystemConfig is OwnableUpgradeable, Semver {
             _batcherHash: _batcherHash,
             _gasLimit: _gasLimit,
             _unsafeBlockSigner: _unsafeBlockSigner,
-            _config: _config
+            _config: _config,
+            _l1CrossDomainMessenger: address(0),
+            _l1ERC721Bridge: address(0),
+            _l1StandardBridge: address(0),
+            _l2OutputOracle: address(0),
+            _optimismPortal: address(0)
         });
     }
 
@@ -104,15 +119,43 @@ contract SystemConfig is OwnableUpgradeable, Semver {
         bytes32 _batcherHash,
         uint64 _gasLimit,
         address _unsafeBlockSigner,
-        ResourceMetering.ResourceConfig memory _config
+        ResourceMetering.ResourceConfig memory _config,
+        address _l1CrossDomainMessenger,
+        address _l1ERC721Bridge,
+        address _l1StandardBridge,
+        address _l2OutputOracle,
+        address _optimismPortal
     ) public initializer {
         __Ownable_init();
         transferOwnership(_owner);
+
+        // TODO: this needs to be backwards compatible with
+        // chains that already have it set.
+        startBlock = block.number;
+        // Could add an extra arg that is an override and do
+        // something like:
+        /*
+        if (_startBlock != 0) startBlock = _startBlock;
+        else startBlock = block.number;
+        */
+       // And then in the next upgrade, remove the extra arg
+        // and move to something like:
+       /*
+        if (startBlock == 0) startBlock = block.number;
+        */
+
         overhead = _overhead;
         scalar = _scalar;
         batcherHash = _batcherHash;
         gasLimit = _gasLimit;
         _setUnsafeBlockSigner(_unsafeBlockSigner);
+
+        _setAddress(_l1CrossDomainMessenger, L1_CROSS_DOMAIN_MESSENGER_SLOT);
+        _setAddress(_l1ERC721Bridge, L1_ERC_721_BRIDGE_SLOT);
+        _setAddress(_l1StandardBridge, L1_STANDARD_BRIDGE_SLOT);
+        _setAddress(_l2OutputOracle, L2_OUTPUT_ORACLE_SLOT);
+        _setAddress(_optimismPortal, OPTIMISM_PORTAL_SLOT);
+
         _setResourceConfig(_config);
         require(_gasLimit >= minimumGasLimit(), "SystemConfig: gas limit too low");
     }
@@ -141,6 +184,14 @@ contract SystemConfig is OwnableUpgradeable, Semver {
         return addr;
     }
 
+    /// @notice
+    function _setAddress(address _addr, bytes32 _slot) internal {
+        bytes32 slot = _slot;
+        assembly {
+            sstore(slot, _addr)
+        }
+    }
+
     /// @notice Updates the unsafe block signer address.
     /// @param _unsafeBlockSigner New unsafe block signer address.
     function setUnsafeBlockSigner(address _unsafeBlockSigner) external onlyOwner {