From 0d43c14b9309610b8091a096c3555309a3f0152c Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Thu, 25 Jul 2024 21:07:58 +0100
Subject: [PATCH] Internals: Remove redundant hash lookup (#5276 partial)
 (#5303)

Minor help for #5276
---
 src/V3Dfg.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/V3Dfg.cpp b/src/V3Dfg.cpp
index d9647a0f7..7df05cbb4 100644
--- a/src/V3Dfg.cpp
+++ b/src/V3Dfg.cpp
@@ -360,8 +360,8 @@ bool DfgVertex::equals(const DfgVertex& that, EqualsCache& cache) const {
 
     const auto key = (this < &that) ? EqualsCache::key_type{this, &that}  //
                                     : EqualsCache::key_type{&that, this};
-    // Note: the recursive invocation can cause a re-hash of the cache which invalidates iterators
-    uint8_t result = cache[key];
+    // Note: the recursive invocation can cause a re-hash but that will not invalidate references
+    uint8_t& result = cache[key];
     if (!result) {
         result = 2;  // Assume equals
         auto thisPair = this->sourceEdges();
@@ -380,7 +380,6 @@ bool DfgVertex::equals(const DfgVertex& that, EqualsCache& cache) const {
                 break;
             }
         }
-        cache[key] = result;
     }
     return result >> 1;
 }