From 164093cb50b5287dee07de1b4fdfe6aca685ddf3 Mon Sep 17 00:00:00 2001
From: Emmanuel T Odeke <odeke@ualberta.ca>
Date: Fri, 22 Apr 2022 00:30:15 +0100
Subject: [PATCH] eth/tracers/logger: remove unnecessary comparisons in
 accessList.equal (#24663)

This change removes extraneous/unnecessary checks for equality
when comparing 2 accessList values A and B. Given that we validate that
their lengths of A and B are equal, if so and if every element in A is
in B, reflexively every element in B is already in A. If that weren't
the case and an element g existed in A but not in B, that would mean
that there is an extra element and hence a mathematical contradiction.

Fixes #24658
---
 core/vm/access_list_tracer.go | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/core/vm/access_list_tracer.go b/core/vm/access_list_tracer.go
index 97dd59fac8ce..db7d1022b09b 100644
--- a/core/vm/access_list_tracer.go
+++ b/core/vm/access_list_tracer.go
@@ -61,16 +61,14 @@ func (al accessList) equal(other accessList) bool {
 	if len(al) != len(other) {
 		return false
 	}
+	// Given that len(al) == len(other), we only need to check that
+	// all the items from al are in other.
 	for addr := range al {
 		if _, ok := other[addr]; !ok {
 			return false
 		}
 	}
-	for addr := range other {
-		if _, ok := al[addr]; !ok {
-			return false
-		}
-	}
+
 	// Accounts match, cross reference the storage slots too
 	for addr, slots := range al {
 		otherslots := other[addr]
@@ -78,16 +76,13 @@ func (al accessList) equal(other accessList) bool {
 		if len(slots) != len(otherslots) {
 			return false
 		}
+		// Given that len(slots) == len(otherslots), we only need to check that
+		// all the items from slots are in otherslots.
 		for hash := range slots {
 			if _, ok := otherslots[hash]; !ok {
 				return false
 			}
 		}
-		for hash := range otherslots {
-			if _, ok := slots[hash]; !ok {
-				return false
-			}
-		}
 	}
 	return true
 }