From 946d69561b50f788d6e43a172c565814005c99f4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@des.dev>
Date: Thu, 25 Jul 2024 20:59:57 +0200
Subject: [PATCH] Avoid needless hash table churn.

When reallocating, check that the pointer changed before updating the
hash table.  Otherwise, we're just removing then re-adding the same
value.  This frequently happens when the allocation is shrinking, or
only growing by a few bytes.
---
 lib/xmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/xmalloc.c b/lib/xmalloc.c
index c445f67..a606d35 100644
--- a/lib/xmalloc.c
+++ b/lib/xmalloc.c
@@ -338,7 +338,7 @@ xrealloc_impl(void *ptr, size_t new_size, const char *file, int line,
     xmalloc_fail_after--;
 
   new_ptr = realloc(ptr, new_size);
-  if (new_ptr != NULL)
+  if (new_ptr != NULL && new_ptr != ptr)
     {
       hash_table_del(xmalloc_table, ptr);
       hash_table_add(xmalloc_table, new_ptr, (int)new_size, file, line, func);