chore: optimize Base module a bit (#261)

.forge-snapshots/ModularAccount_Runtime_InstallSessionKey_Case1.snap

@@ -1 +1 @@
-423918
+423482

.forge-snapshots/ModularAccount_Runtime_UseSessionKey_Case1_Counter.snap

@@ -1 +1 @@
-79484
+78838

.forge-snapshots/ModularAccount_Runtime_UseSessionKey_Case1_Token.snap

@@ -1 +1 @@
-113042
+112223

.forge-snapshots/ModularAccount_UserOp_InstallSessionKey_Case1.snap

@@ -1 +1 @@
-532152
+531716

.forge-snapshots/ModularAccount_UserOp_UseSessionKey_Case1_Counter.snap

@@ -1 +1 @@
-195938
+195559

.forge-snapshots/ModularAccount_UserOp_UseSessionKey_Case1_Token.snap

@@ -1 +1 @@
-227062
+226591

.forge-snapshots/SemiModularAccount_Runtime_InstallSessionKey_Case1.snap

@@ -1 +1 @@
-422598
+422162

.forge-snapshots/SemiModularAccount_Runtime_UseSessionKey_Case1_Counter.snap

@@ -1 +1 @@
-79900
+79254

.forge-snapshots/SemiModularAccount_Runtime_UseSessionKey_Case1_Token.snap

@@ -1 +1 @@
-113458
+112639

.forge-snapshots/SemiModularAccount_UserOp_InstallSessionKey_Case1.snap

@@ -1 +1 @@
-529725
+529289

.forge-snapshots/SemiModularAccount_UserOp_UseSessionKey_Case1_Counter.snap

@@ -1 +1 @@
-196232
+195853

.forge-snapshots/SemiModularAccount_UserOp_UseSessionKey_Case1_Token.snap

@@ -1 +1 @@
-227368
+226897

src/modules/BaseModule.sol

@@ -58,24 +58,26 @@ abstract contract BaseModule is ERC165, IModule {
     /// @dev help method that returns extracted selector and calldata. If selector is executeUserOp, return the
     /// selector and calldata of the inner call.
     function _getSelectorAndCalldata(bytes calldata data) internal pure returns (bytes4, bytes memory) {
-        if (bytes4(data[:4]) == IAccountExecute.executeUserOp.selector) {
+        bytes4 selector = bytes4(data[:4]);
+        if (selector == IAccountExecute.executeUserOp.selector) {
             (PackedUserOperation memory uo,) = abi.decode(data[4:], (PackedUserOperation, bytes32));
-            bytes4 selector;
-            bytes memory callData = uo.callData;
+            bytes memory finalCalldata = uo.callData;
             // Bytes arr representation: [bytes32(len), bytes4(executeUserOp.selector), bytes4(actualSelector),
             // bytes(actualCallData)]
-            // 1. Copy actualSelector into a new var
-            // 2. Shorten bytes arry by 8 by: store length - 8 into the new pointer location
-            // 3. Move the callData pointer by 8
-            assembly {
-                selector := mload(add(callData, 36))
+            assembly ("memory-safe") {
+                // Copy actualSelector into a new var
+                selector := shl(224, mload(add(finalCalldata, 8)))
 
-                let len := mload(callData)
-                mstore(add(callData, 8), sub(len, 8))
-                callData := add(callData, 8)
+                let len := mload(finalCalldata)
+
+                // Move the finalCalldata pointer by 8
+                finalCalldata := add(finalCalldata, 8)
+
+                // Shorten bytes arry by 8 by: store length - 8 into the new pointer location
+                mstore(finalCalldata, sub(len, 8))
             }
-            return (selector, callData);
+            return (selector, finalCalldata);
         }
-        return (bytes4(data[:4]), data[4:]);
+        return (selector, data[4:]);
     }
 }