From cd67eace8caa4e3db7b4c8454c30b2caf6958548 Mon Sep 17 00:00:00 2001
From: robinsdan <115981357+robinsdan@users.noreply.github.com>
Date: Mon, 16 Oct 2023 18:15:49 +0800
Subject: [PATCH] perf: move common_prefix_len out of loop (#5036)

---
 crates/primitives/src/trie/hash_builder/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/primitives/src/trie/hash_builder/mod.rs b/crates/primitives/src/trie/hash_builder/mod.rs
index 35a41243da..888bb8ce68 100644
--- a/crates/primitives/src/trie/hash_builder/mod.rs
+++ b/crates/primitives/src/trie/hash_builder/mod.rs
@@ -182,6 +182,7 @@ impl HashBuilder {
 
         tracing::debug!(target: "trie::hash_builder", ?current, ?succeeding, "updating merkle tree");
 
+        let common_prefix_len = succeeding.common_prefix_length(&current);
         let mut i = 0;
         loop {
             let span = tracing::span!(
@@ -197,7 +198,6 @@ impl HashBuilder {
             let preceding_exists = !self.groups.is_empty();
             let preceding_len: usize = self.groups.len().saturating_sub(1);
 
-            let common_prefix_len = succeeding.common_prefix_length(&current);
             let len = std::cmp::max(preceding_len, common_prefix_len);
             assert!(len < current.len());