From 01b8f5e8821eac0e3456d6200b351629fd3752f4 Mon Sep 17 00:00:00 2001
From: zhangyunhao <zhangyunhao@bytedance.com>
Date: Tue, 19 Apr 2022 16:38:04 +0800
Subject: [PATCH] runtime: use fastrand64 in mapiterinit

Change-Id: I5698c7576a0f39ae62de7bea64286ac8e578d421
Reviewed-on: https://go-review.googlesource.com/c/go/+/400916
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
---
 src/runtime/map.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/runtime/map.go b/src/runtime/map.go
index e91b25eaec..2e513e2d52 100644
--- a/src/runtime/map.go
+++ b/src/runtime/map.go
@@ -842,9 +842,11 @@ func mapiterinit(t *maptype, h *hmap, it *hiter) {
 	}
 
 	// decide where to start
-	r := uintptr(fastrand())
+	var r uintptr
 	if h.B > 31-bucketCntBits {
-		r += uintptr(fastrand()) << 31
+		r = uintptr(fastrand64())
+	} else {
+		r = uintptr(fastrand())
 	}
 	it.startBucket = r & bucketMask(h.B)
 	it.offset = uint8(r >> h.B & (bucketCnt - 1))