Address comments

src/account/AccountLoupe.sol

@@ -42,7 +42,6 @@ abstract contract AccountLoupe is IAccountLoupe {
         uint256 preExecHooksLength = selectorData.preHooks.length();
         uint256 postOnlyExecHooksLength = selectorData.postOnlyHooks.length();
 
-        // Overallocate on length - not all of this may get filled up. We set the correct length later.
         execHooks = new ExecutionHooks[](preExecHooksLength + postOnlyExecHooksLength);
 
         for (uint256 i = 0; i < preExecHooksLength; ++i) {

src/account/AccountStorage.sol

@@ -34,6 +34,10 @@ struct SelectorData {
     // The plugin that implements this execution function.
     // If this is a native function, the address must remain address(0).
     address plugin;
+    // How many times a `PRE_HOOK_ALWAYS_DENY` has been added for this function.
+    // Since that is the only type of hook that may overlap, we can use this to track the number of times it has
+    // been applied, and whether or not the deny should apply. The size `uint48` was chosen somewhat arbitrarily,
+    // but it packs alongside `plugin` while still leaving some other space in the slot for future packing.
     uint48 denyExecutionCount;
     // User operation validation and runtime validation share a function reference.
     FunctionReference validation;
@@ -73,9 +77,9 @@ function getPermittedCallKey(address addr, bytes4 selector) pure returns (bytes2
     return bytes24(bytes20(addr)) | (bytes24(selector) >> 160);
 }
 
-// Helper function to get all elements of a set into memory.
 using EnumerableSet for EnumerableSet.Bytes32Set;
 
+/// @dev Helper function to get all elements of a set into memory.
 function toFunctionReferenceArray(EnumerableSet.Bytes32Set storage set)
     view
     returns (FunctionReference[] memory)

src/account/PluginManagerInternals.sol

@@ -103,7 +103,7 @@ abstract contract PluginManagerInternals is IPluginManager {
 
         if (!preExecHook.isEmpty()) {
             if (preExecHook.eq(FunctionReferenceLib._PRE_HOOK_ALWAYS_DENY)) {
-                // Increment the overlappingDenies counter.
+                // Increment `denyExecutionCount`, because this pre exec hook may be applied multiple times.
                 _selectorData.denyExecutionCount += 1;
                 return;
             }
@@ -133,7 +133,7 @@ abstract contract PluginManagerInternals is IPluginManager {
 
         if (!preExecHook.isEmpty()) {
             if (preExecHook.eq(FunctionReferenceLib._PRE_HOOK_ALWAYS_DENY)) {
-                // Decrement the overlappingDenies counter.
+                // Decrement `denyExecutionCount`, because this pre exec hook may be applied multiple times.
                 _selectorData.denyExecutionCount -= 1;
                 return;
             }

src/account/UpgradeableModularAccount.sol

@@ -464,7 +464,7 @@ contract UpgradeableModularAccount is
 
             FunctionReference associatedPostExecHook = selectorData.associatedPostHooks[preExecHook];
 
-            if (associatedPostExecHook.notEq(FunctionReferenceLib._EMPTY_FUNCTION_REFERENCE)) {
+            if (associatedPostExecHook.notEmpty()) {
                 postHooksToRun[i + postOnlyHooksLength].postExecHook = associatedPostExecHook;
             }
         }
@@ -485,7 +485,7 @@ contract UpgradeableModularAccount is
 
             // If there is an associated post-exec hook, save the return data.
             PostExecToRun memory postExecToRun = postHooksToRun[i + postOnlyHooksLength];
-            if (postExecToRun.postExecHook.notEq(FunctionReferenceLib._EMPTY_FUNCTION_REFERENCE)) {
+            if (postExecToRun.postExecHook.notEmpty()) {
                 postExecToRun.preExecHookReturnData = preExecHookReturnData;
             }
         }
@@ -514,7 +514,7 @@ contract UpgradeableModularAccount is
 
             PostExecToRun memory postHookToRun = postHooksToRun[i];
 
-            if (postHookToRun.postExecHook.eq(FunctionReferenceLib._EMPTY_FUNCTION_REFERENCE)) {
+            if (postHookToRun.postExecHook.isEmpty()) {
                 // This is an empty post hook, from a pre-only hook, so we skip it.
                 continue;
             }

src/helpers/FunctionReferenceLib.sol

@@ -26,6 +26,10 @@ library FunctionReferenceLib {
         return FunctionReference.unwrap(fr) == bytes21(0);
     }
 
+    function notEmpty(FunctionReference fr) internal pure returns (bool) {
+        return FunctionReference.unwrap(fr) != bytes21(0);
+    }
+
     function isEmptyOrMagicValue(FunctionReference fr) internal pure returns (bool) {
         return FunctionReference.unwrap(fr) <= bytes21(uint168(2));
     }