From a25b7eccf928d7478465599e45cabbf1cb6fd0c1 Mon Sep 17 00:00:00 2001
From: Mahesh Madhav <67384846+heshpdx@users.noreply.github.com>
Date: Wed, 4 Sep 2024 21:38:25 -0700
Subject: [PATCH] optimize computation in librrgraph utils

In one hot loop, swap three expensive FDIVs for a single FDIV and three FMULs.
---
 .../src/utils/alloc_and_load_rr_indexed_data.cpp           | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libs/librrgraph/src/utils/alloc_and_load_rr_indexed_data.cpp b/libs/librrgraph/src/utils/alloc_and_load_rr_indexed_data.cpp
index 7eb6ded1579..6b5634de641 100644
--- a/libs/librrgraph/src/utils/alloc_and_load_rr_indexed_data.cpp
+++ b/libs/librrgraph/src/utils/alloc_and_load_rr_indexed_data.cpp
@@ -678,9 +678,10 @@ static void calculate_average_switch(const RRGraphView& rr_graph, int inode, dou
     }
 
     if (num_switches > 0) {
-        avg_switch_R /= num_switches;
-        avg_switch_T /= num_switches;
-        avg_switch_Cinternal /= num_switches;
+        double inv_num_switches = 1.0 / num_switches;
+        avg_switch_R *= inv_num_switches;
+        avg_switch_T *= inv_num_switches;
+        avg_switch_Cinternal *= inv_num_switches;
     }
 
     VTR_ASSERT(std::isfinite(avg_switch_R));