From 5866ec05f5a2a613501095e1de64d641ad898021 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 29 Apr 2022 13:14:41 -0600
Subject: [PATCH] [benchmark-map] Remove rand() overhead from benchmark

---
 perf/benchmark-map.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/perf/benchmark-map.cc b/perf/benchmark-map.cc
index 7ec891135..8f4eb1e80 100644
--- a/perf/benchmark-map.cc
+++ b/perf/benchmark-map.cc
@@ -29,11 +29,13 @@ static void BM_MapInsert(benchmark::State& state) {
   RandomMap(map_size, original);
   assert(hb_map_get_population(original) == map_size);
 
+  auto needle = map_size / 2;
+  auto v = 0;
   for (auto _ : state) {
     // TODO(garretrieger): create a copy of the original map.
     //                     Needs a hb_map_copy(..) in public api.
 
-    hb_map_set (original, rand (), rand ());
+    hb_map_set (original, needle++, v++);
   }
 
   hb_map_destroy(original);
@@ -49,9 +51,11 @@ static void BM_MapLookup(benchmark::State& state) {
   RandomMap(map_size, original);
   assert(hb_map_get_population(original) == map_size);
 
+  auto needle = map_size / 2;
+
   for (auto _ : state) {
     benchmark::DoNotOptimize(
-        hb_map_get (original, rand()));
+        hb_map_get (original, needle++));
   }
 
   hb_map_destroy(original);