From 9220c68408d47677d8cd7c548d3a5861365dd24e Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 15 Sep 2023 10:45:06 +0200
Subject: [PATCH] LibJS: Avoid pointless HashTable copying during GC mark phase

for_each_cell_among_possible_pointers() was taking HashTable by value
instead of by const reference for no reason.

The copying was soaking up ~4% of CPU time while loading https://x.com/
---
 Userland/Libraries/LibJS/Heap/Heap.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Userland/Libraries/LibJS/Heap/Heap.cpp b/Userland/Libraries/LibJS/Heap/Heap.cpp
index d24d03108e..ba98c73f33 100644
--- a/Userland/Libraries/LibJS/Heap/Heap.cpp
+++ b/Userland/Libraries/LibJS/Heap/Heap.cpp
@@ -114,7 +114,7 @@ static void add_possible_value(HashMap<FlatPtr, HeapRootTypeOrLocation>& possibl
 }
 
 template<typename Callback>
-static void for_each_cell_among_possible_pointers(HashTable<HeapBlock*> all_live_heap_blocks, HashMap<FlatPtr, HeapRootTypeOrLocation>& possible_pointers, Callback callback)
+static void for_each_cell_among_possible_pointers(HashTable<HeapBlock*> const& all_live_heap_blocks, HashMap<FlatPtr, HeapRootTypeOrLocation>& possible_pointers, Callback callback)
 {
     for (auto possible_pointer : possible_pointers.keys()) {
         if (!possible_pointer)