feat(ctb): inline verification function

Inlines verifyInclusionProof because it was only being used once.

packages/contracts-bedrock/.gas-snapshot

@@ -8,7 +8,7 @@ GasBenchMark_L1StandardBridge_Finalize:test_finalizeETHWithdrawal_benchmark() (g
 GasBenchMark_L2OutputOracle:test_proposeL2Output_benchmark() (gas: 88513)
 GasBenchMark_OptimismPortal:test_depositTransaction_benchmark() (gas: 74998)
 GasBenchMark_OptimismPortal:test_depositTransaction_benchmark_1() (gas: 36156)
-GasBenchMark_OptimismPortal:test_proveWithdrawalTransaction_benchmark() (gas: 167240)
+GasBenchMark_OptimismPortal:test_proveWithdrawalTransaction_benchmark() (gas: 167187)
 Bytes_Test:test_slice_acrossMultipleWords_works() (gas: 9391)
 Bytes_Test:test_slice_acrossWords_works() (gas: 1397)
 Bytes_Test:test_slice_fromNonZeroIdx_works() (gas: 17218)
@@ -213,23 +213,23 @@ OptimismPortalUpgradeable_Test:test_initialize_cannotInitImpl_reverts() (gas: 10
 OptimismPortalUpgradeable_Test:test_initialize_cannotInitProxy_reverts() (gas: 15833)
 OptimismPortalUpgradeable_Test:test_params_initValuesOnProxy_succeeds() (gas: 16011)
 OptimismPortalUpgradeable_Test:test_upgradeToAndCall_upgrading_succeeds() (gas: 180457)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifOutputRootChanges_reverts() (gas: 198817)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifOutputTimestampIsNotFinalized_reverts() (gas: 201136)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifOutputRootChanges_reverts() (gas: 198764)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifOutputTimestampIsNotFinalized_reverts() (gas: 201083)
 OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifWithdrawalNotProven_reverts() (gas: 39656)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifWithdrawalProofNotOldEnough_reverts() (gas: 196181)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onInsufficientGas_reverts() (gas: 197007)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onRecentWithdrawal_reverts() (gas: 176895)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onReentrancy_reverts() (gas: 235453)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onReplay_reverts() (gas: 236959)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_provenWithdrawalHash_succeeds() (gas: 228640)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_targetFails_fails() (gas: 8797746687696163641)
-OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_timestampLessThanL2OracleStart_reverts() (gas: 192905)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_ifWithdrawalProofNotOldEnough_reverts() (gas: 196128)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onInsufficientGas_reverts() (gas: 196954)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onRecentWithdrawal_reverts() (gas: 176842)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onReentrancy_reverts() (gas: 235400)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_onReplay_reverts() (gas: 236906)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_provenWithdrawalHash_succeeds() (gas: 228587)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_targetFails_fails() (gas: 8797746687696163638)
+OptimismPortal_FinalizeWithdrawal_Test:test_finalizeWithdrawalTransaction_timestampLessThanL2OracleStart_reverts() (gas: 192852)
 OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_onInvalidOutputRootProof_reverts() (gas: 83498)
-OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_onInvalidWithdrawalProof_reverts() (gas: 135254)
+OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_onInvalidWithdrawalProof_reverts() (gas: 135224)
 OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_onSelfCall_reverts() (gas: 50732)
-OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_replayProveChangedOutputRoot_succeeds() (gas: 275279)
-OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_replayProve_reverts() (gas: 188183)
-OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_validWithdrawalProof_succeeds() (gas: 178370)
+OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_replayProveChangedOutputRoot_succeeds() (gas: 275173)
+OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_replayProve_reverts() (gas: 188130)
+OptimismPortal_FinalizeWithdrawal_Test:test_proveWithdrawalTransaction_validWithdrawalProof_succeeds() (gas: 178317)
 OptimismPortal_Test:test_constructor_succeeds() (gas: 17277)
 OptimismPortal_Test:test_depositTransaction_contractCreation_reverts() (gas: 14267)
 OptimismPortal_Test:test_depositTransaction_createWithZeroValueForContract_succeeds() (gas: 76662)

packages/contracts-bedrock/contracts/L1/OptimismPortal.sol

@@ -200,14 +200,23 @@ contract OptimismPortal is Initializable, ResourceMetering, Semver {
             "OptimismPortal: withdrawal hash has already been proven"
         );
 
+        // Compute the storage slot of the withdrawal hash in the L2ToL1MessagePasser contract.
+        bytes32 storageKey = keccak256(
+            abi.encode(
+                withdrawalHash,
+                uint256(0) // The withdrawals mapping is at the first slot in the layout.
+            )
+        );
+
         // Verify that the hash of this withdrawal was stored in the L2toL1MessagePasser contract on
         // L2. If this is true, then we know that this withdrawal was actually triggered on L2
         // and can therefore be relayed on L1.
         require(
-            _verifyWithdrawalInclusion(
-                withdrawalHash,
-                _outputRootProof.messagePasserStorageRoot,
-                _withdrawalProof
+            SecureMerkleTrie.verifyInclusionProof(
+                abi.encode(storageKey),
+                hex"01",
+                _withdrawalProof,
+                _outputRootProof.messagePasserStorageRoot
             ),
             "OptimismPortal: invalid withdrawal inclusion proof"
         );
@@ -390,33 +399,4 @@ contract OptimismPortal is Initializable, ResourceMetering, Semver {
     function _isFinalizationPeriodElapsed(uint256 _timestamp) internal view returns (bool) {
         return block.timestamp > _timestamp + FINALIZATION_PERIOD_SECONDS;
     }
-
-    /**
-     * @notice Verifies a Merkle Trie inclusion proof that a given withdrawal hash is present in
-     *         the storage of the L2ToL1MessagePasser contract.
-     *
-     * @param _withdrawalHash Hash of the withdrawal to verify.
-     * @param _storageRoot    Root of the storage of the L2ToL1MessagePasser contract.
-     * @param _proof          Inclusion proof of the withdrawal hash in the storage root.
-     */
-    function _verifyWithdrawalInclusion(
-        bytes32 _withdrawalHash,
-        bytes32 _storageRoot,
-        bytes[] memory _proof
-    ) internal pure returns (bool) {
-        bytes32 storageKey = keccak256(
-            abi.encode(
-                _withdrawalHash,
-                uint256(0) // The withdrawals mapping is at the first slot in the layout.
-            )
-        );
-
-        return
-            SecureMerkleTrie.verifyInclusionProof(
-                abi.encode(storageKey),
-                hex"01",
-                _proof,
-                _storageRoot
-            );
-    }
 }