internal/runtime/cgobench: add Go function call benchmark for comparison

Change-Id: I0ada7fa02eb5f18a78da17bdcfc63333abbd8450
Reviewed-on: https://go-review.googlesource.com/c/go/+/713284
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>

src/internal/runtime/cgobench/bench_test.go

@@ -11,13 +11,13 @@ import (
 	"testing"
 )
 
-func BenchmarkCgoCall(b *testing.B) {
+func BenchmarkCall(b *testing.B) {
 	for b.Loop() {
 		cgobench.Empty()
 	}
 }
 
-func BenchmarkCgoCallParallel(b *testing.B) {
+func BenchmarkCallParallel(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
 			cgobench.Empty()
@@ -25,16 +25,30 @@ func BenchmarkCgoCallParallel(b *testing.B) {
 	})
 }
 
+func BenchmarkCgoCall(b *testing.B) {
+	for b.Loop() {
+		cgobench.EmptyC()
+	}
+}
+
+func BenchmarkCgoCallParallel(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			cgobench.EmptyC()
+		}
+	})
+}
+
 func BenchmarkCgoCallWithCallback(b *testing.B) {
 	for b.Loop() {
-		cgobench.Callback()
+		cgobench.CallbackC()
 	}
 }
 
 func BenchmarkCgoCallParallelWithCallback(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
-			cgobench.Callback()
+			cgobench.CallbackC()
 		}
 	})
 }

src/internal/runtime/cgobench/funcs.go

@@ -19,14 +19,18 @@ static void callback() {
 */
 import "C"
 
-func Empty() {
+func EmptyC() {
 	C.empty()
 }
 
-func Callback() {
+func CallbackC() {
 	C.callback()
 }
 
 //export go_empty_callback
 func go_empty_callback() {
 }
+
+//go:noinline
+func Empty() {
+}