go/printer: report allocs and set bytes

We now get more than just time/op.

	name      time/op
	Print-16    6.29ms ± 3%

	name      speed
	Print-16  8.25MB/s ± 3%

	name      alloc/op
	Print-16     483kB ± 0%

	name      allocs/op
	Print-16     17.8k ± 0%

Change-Id: I6b5e9a30a826ff8603724bd5983e6b7f5ec12708
Reviewed-on: https://go-review.googlesource.com/c/go/+/412554
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Ian Lance Taylor <iant@google.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/go/printer/performance_test.go b/src/go/printer/performance_test.go
index e655fa13ee..ea6a98caa4 100644
--- a/src/go/printer/performance_test.go
+++ b/src/go/printer/performance_test.go
@@ -17,7 +17,10 @@ import (
 	"testing"
 )
 
-var testfile *ast.File
+var (
+	testfile *ast.File
+	testsize int64
+)
 
 func testprint(out io.Writer, file *ast.File) {
 	if err := (&Config{TabIndent | UseSpaces | normalizeNumbers, 8, 0}).Fprint(out, fset, file); err != nil {
@@ -46,12 +49,15 @@ func initialize() {
 	}
 
 	testfile = file
+	testsize = int64(len(src))
 }
 
 func BenchmarkPrint(b *testing.B) {
 	if testfile == nil {
 		initialize()
 	}
+	b.ReportAllocs()
+	b.SetBytes(testsize)
 	for i := 0; i < b.N; i++ {
 		testprint(io.Discard, testfile)
 	}