From 6fad4b8409c4105a5334b7be6aac1981dc6c0275 Mon Sep 17 00:00:00 2001
From: 0x471 <0x471@protonmail.com>
Date: Wed, 1 Jan 2025 18:45:56 +0000
Subject: [PATCH 1/3] perf(merkle): optimize Poseidon hash using direct
 hades_permutation

---
 packages/merkle_tree/src/hashes.cairo | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/packages/merkle_tree/src/hashes.cairo b/packages/merkle_tree/src/hashes.cairo
index 0ad9921c2..b2834c8bb 100644
--- a/packages/merkle_tree/src/hashes.cairo
+++ b/packages/merkle_tree/src/hashes.cairo
@@ -5,6 +5,7 @@ use core::hash::HashStateTrait;
 use core::pedersen::PedersenTrait;
 use core::poseidon::PoseidonTrait;
 use core::traits::PartialOrd;
+use core::poseidon::hades_permutation;
 
 /// Computes a commutative hash of a sorted pair of felt252 values.
 ///
@@ -33,14 +34,15 @@ pub impl PedersenCHasher of CommutativeHasher {
 
 /// Computes the Poseidon commutative hash of a sorted pair of felt252 values.
 pub impl PoseidonCHasher of CommutativeHasher {
-    /// Computes the Poseidon hash of the concatenation of two values, sorting the pair first.
+    /// Computes the Poseidon hash by directly using hades_permutation with the two values
+    /// and a length indicator, sorting the pair first.
     fn commutative_hash(a: felt252, b: felt252) -> felt252 {
-        let hash_state = PoseidonTrait::new();
-        if a < b {
-            hash_state.update(a).update(b).finalize()
+        let (result, _, _) = if a < b {
+            hades_permutation(a, b, 2)
         } else {
-            hash_state.update(b).update(a).finalize()
-        }
+            hades_permutation(b, a, 2)
+        };
+        result
     }
 }
 

From 730467408f5fae4d3e37e6fde1bb356aa30dd118 Mon Sep 17 00:00:00 2001
From: 0x471 <0x471@protonmail.com>
Date: Sat, 4 Jan 2025 14:48:30 +0000
Subject: [PATCH 2/3] docs: clarify sorting behavior in PoseidonCHasher comment

---
 packages/merkle_tree/src/hashes.cairo | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/merkle_tree/src/hashes.cairo b/packages/merkle_tree/src/hashes.cairo
index b2834c8bb..3a681e681 100644
--- a/packages/merkle_tree/src/hashes.cairo
+++ b/packages/merkle_tree/src/hashes.cairo
@@ -34,8 +34,7 @@ pub impl PedersenCHasher of CommutativeHasher {
 
 /// Computes the Poseidon commutative hash of a sorted pair of felt252 values.
 pub impl PoseidonCHasher of CommutativeHasher {
-    /// Computes the Poseidon hash by directly using hades_permutation with the two values
-    /// and a length indicator, sorting the pair first.
+    /// Computes the Poseidon hash of two values, sorting the pair first.
     fn commutative_hash(a: felt252, b: felt252) -> felt252 {
         let (result, _, _) = if a < b {
             hades_permutation(a, b, 2)

From eaa98c7e872227a953f5541137fdb6e5ad788a72 Mon Sep 17 00:00:00 2001
From: 0x471 <0x471@protonmail.com>
Date: Sat, 4 Jan 2025 14:54:34 +0000
Subject: [PATCH 3/3] style: format merkle-tree/hashes.cairo

---
 packages/merkle_tree/src/hashes.cairo | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/merkle_tree/src/hashes.cairo b/packages/merkle_tree/src/hashes.cairo
index 3a681e681..31cb11677 100644
--- a/packages/merkle_tree/src/hashes.cairo
+++ b/packages/merkle_tree/src/hashes.cairo
@@ -4,8 +4,8 @@
 use core::hash::HashStateTrait;
 use core::pedersen::PedersenTrait;
 use core::poseidon::PoseidonTrait;
-use core::traits::PartialOrd;
 use core::poseidon::hades_permutation;
+use core::traits::PartialOrd;
 
 /// Computes a commutative hash of a sorted pair of felt252 values.
 ///