From 75773b0e7b4dac6b779e869a13096a7b7f0be5bb Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Tue, 5 Oct 2021 09:40:15 -0700
Subject: [PATCH] runtime: add BenchmarkStackCopyWithStkobj

For benchmarking and improving recent stkobj-related changes.

Co-Authored-By: Cherry Mui <cherryyz@google.com>
Change-Id: I34c8b1a09e4cf98547460882b0d3908158269f57
Reviewed-on: https://go-review.googlesource.com/c/go/+/354071
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---
 src/runtime/stack_test.go | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/runtime/stack_test.go b/src/runtime/stack_test.go
index 43fc5cac55..3f02243a1e 100644
--- a/src/runtime/stack_test.go
+++ b/src/runtime/stack_test.go
@@ -585,6 +585,34 @@ func count21(n int) int { return 1 + count22(n-1) }
 func count22(n int) int { return 1 + count23(n-1) }
 func count23(n int) int { return 1 + count1(n-1) }
 
+type stkobjT struct {
+	p *stkobjT
+	x int64
+	y [20]int // consume some stack
+}
+
+// Sum creates a linked list of stkobjTs.
+func Sum(n int64, p *stkobjT) {
+	if n == 0 {
+		return
+	}
+	s := stkobjT{p: p, x: n}
+	Sum(n-1, &s)
+	p.x += s.x
+}
+
+func BenchmarkStackCopyWithStkobj(b *testing.B) {
+	c := make(chan bool)
+	for i := 0; i < b.N; i++ {
+		go func() {
+			var s stkobjT
+			Sum(100000, &s)
+			c <- true
+		}()
+		<-c
+	}
+}
+
 type structWithMethod struct{}
 
 func (s structWithMethod) caller() string {