testing: introduce (*B).ReportAllocs()

Calling it will show memory allocation statistics for that
single benchmark (if -test.benchmem is not provided)

R=golang-dev, rsc, kevlar, bradfitz
CC=golang-dev
https://golang.org/cl/7027046

2 files changed, 2 insertions, 14 deletions

diff --git a/src/pkg/exp/html/parse_test.go b/src/pkg/exp/html/parse_test.go
index 7cf2ff4163..4896dfb7a0 100644
--- a/src/pkg/exp/html/parse_test.go
+++ b/src/pkg/exp/html/parse_test.go
@@ -382,15 +382,9 @@ func BenchmarkParser(b *testing.B) {
 	}
 	b.SetBytes(int64(len(buf)))
 	runtime.GC()
-	var ms runtime.MemStats
-	runtime.ReadMemStats(&ms)
-	mallocs := ms.Mallocs
+	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		Parse(bytes.NewBuffer(buf))
 	}
-	b.StopTimer()
-	runtime.ReadMemStats(&ms)
-	mallocs = ms.Mallocs - mallocs
-	b.Logf("%d iterations, %d mallocs per iteration\n", b.N, int(mallocs)/b.N)
 }
diff --git a/src/pkg/exp/html/token_test.go b/src/pkg/exp/html/token_test.go
index 63a8bfc483..14e23467f4 100644
--- a/src/pkg/exp/html/token_test.go
+++ b/src/pkg/exp/html/token_test.go
@@ -634,9 +634,7 @@ func benchmarkTokenizer(b *testing.B, level int) {
 	}
 	b.SetBytes(int64(len(buf)))
 	runtime.GC()
-	var ms runtime.MemStats
-	runtime.ReadMemStats(&ms)
-	mallocs := ms.Mallocs
+	b.ReportAllocs()
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		z := NewTokenizer(bytes.NewBuffer(buf))
@@ -674,10 +672,6 @@ func benchmarkTokenizer(b *testing.B, level int) {
 			}
 		}
 	}
-	b.StopTimer()
-	runtime.ReadMemStats(&ms)
-	mallocs = ms.Mallocs - mallocs
-	b.Logf("%d iterations, %d mallocs per iteration\n", b.N, int(mallocs)/b.N)
 }
 
 func BenchmarkRawLevelTokenizer(b *testing.B)  { benchmarkTokenizer(b, rawLevel) }