runtime: add interface microbenchmarks

2011 Mac Mini, Core i5 @ 2.3Ghz

BenchmarkConvT2E        50000000                40.4 ns/op
BenchmarkConvT2EBig     20000000               107 ns/op
BenchmarkConvT2I        100000000               28.9 ns/op
BenchmarkConvI2E        500000000                5.93 ns/op
BenchmarkConvI2I        100000000               19.0 ns/op
BenchmarkAssertE2T      100000000               14.1 ns/op
BenchmarkAssertE2TBig   100000000               17.8 ns/op
BenchmarkAssertE2I      100000000               21.3 ns/op
BenchmarkAssertI2T      100000000               14.3 ns/op
BenchmarkAssertI2I      100000000               20.8 ns/op
BenchmarkAssertI2E      500000000                5.58 ns/op

Pandaboard, 2 x Omap4 @ 1.2Ghz

BenchmarkConvT2E        10000000               215 ns/op
BenchmarkConvT2EBig      1000000              3697 ns/op
BenchmarkConvT2I         5000000               666 ns/op
BenchmarkConvI2E        50000000                42.4 ns/op
BenchmarkConvI2I         5000000               489 ns/op
BenchmarkAssertE2T      20000000                90.0 ns/op
BenchmarkAssertE2TBig   20000000                91.6 ns/op
BenchmarkAssertE2I       5000000               515 ns/op
BenchmarkAssertI2T      20000000               124 ns/op
BenchmarkAssertI2I       5000000               517 ns/op
BenchmarkAssertI2E      50000000                47.2 ns/op
BenchmarkAssertE2E      50000000                42.7 ns/op

R=minux.ma, rsc, fullung, bsiegert, dsymonds
CC=golang-dev
https://golang.org/cl/5777048

src/pkg/runtime/iface_test.go

+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"bytes"
+	"io"
+	"testing"
+)
+
+var (
+	I   interface{}
+	J   int
+	B                 = new(bytes.Buffer)
+	W   io.Writer     = B
+	I2  interface{}   = B
+	R   io.ReadWriter = B
+	Big [2]*int
+)
+
+func BenchmarkConvT2E(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		I = 1
+	}
+}
+
+func BenchmarkConvT2EBig(b *testing.B) {
+	v := [2]*int{}
+	for i := 0; i < b.N; i++ {
+		I = v
+	}
+}
+
+func BenchmarkConvT2I(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		W = B
+	}
+}
+
+func BenchmarkConvI2E(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		I = W
+	}
+}
+
+func BenchmarkConvI2I(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		W = R
+	}
+}
+
+func BenchmarkAssertE2T(b *testing.B) {
+	I = 1
+	for i := 0; i < b.N; i++ {
+		J = I.(int)
+	}
+}
+
+func BenchmarkAssertE2TBig(b *testing.B) {
+	var v interface{} = [2]*int{}
+	for i := 0; i < b.N; i++ {
+		Big = v.([2]*int)
+	}
+}
+
+func BenchmarkAssertE2I(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		W = I2.(io.Writer)
+	}
+}
+
+func BenchmarkAssertI2T(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		B = W.(*bytes.Buffer)
+	}
+}
+
+func BenchmarkAssertI2I(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		W = R.(io.Writer)
+	}
+}
+
+func BenchmarkAssertI2E(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		I = R.(interface{})
+	}
+}
+
+func BenchmarkAssertE2E(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		I = I2.(interface{})
+	}
+}