Fix benchmarks to report proper values. (#7)

```
$ go test -run=NONE -bench .
PASS
BenchmarkHash64-4  	 1000000	      1036 ns/op	  61.77 MB/s
BenchmarkHash128-4 	 2000000	       801 ns/op	 159.67 MB/s
BenchmarkHash1K-4  	  500000	      2464 ns/op	 415.53 MB/s
BenchmarkHash8K-4  	  200000	     11212 ns/op	 730.60 MB/s
BenchmarkHash32K-4 	   30000	     40766 ns/op	 803.80 MB/s
BenchmarkHash128K-4	   10000	    163170 ns/op	 803.28 MB/s
ok  	github.com/minio/blake2b-simd	10.298s
```

blake2b_test.go

@@ -601,50 +601,41 @@ var goldenKeyed = []string{
 var bench = New512()
 var buf = make([]byte, 128*1024)
 
+func benchmarkSize(b *testing.B, size int) {
+	b.SetBytes(int64(size))
+	for i := 0; i < b.N; i++ {
+		bench.Reset()
+		bench.Write(buf[:size])
+		bench.Sum(nil)
+	}
+}
+
 // Benchmark writes of 64 bytes.
 func BenchmarkHash64(b *testing.B) {
-	b.SetBytes(64)
-	for i := 0; i < b.N; i++ {
-		Sum512(buf[:64])
-	}
+	benchmarkSize(b, 64)
 }
 
 // Benchmark writes of 128 bytes.
 func BenchmarkHash128(b *testing.B) {
-	b.SetBytes(128)
-	for i := 0; i < b.N; i++ {
-		Sum512(buf[:128])
-	}
+	benchmarkSize(b, 128)
 }
 
 // Benchmark writes of 1KiB bytes.
-func BenchmarkWrite1K(b *testing.B) {
-	b.SetBytes(1024)
-	for i := 0; i < b.N; i++ {
-		bench.Write(buf[:1024])
-	}
+func BenchmarkHash1K(b *testing.B) {
+	benchmarkSize(b, 1024)
 }
 
 // Benchmark writes of 8KiB bytes.
-func BenchmarkWrite8K(b *testing.B) {
-	b.SetBytes(int64(len(buf)))
-	for i := 0; i < b.N; i++ {
-		bench.Write(buf[:8192])
-	}
+func BenchmarkHash8K(b *testing.B) {
+	benchmarkSize(b, 8*1024)
 }
 
 // Benchmark writes of 32KiB bytes.
-func BenchmarkWrite32K(b *testing.B) {
-	b.SetBytes(int64(len(buf)))
-	for i := 0; i < b.N; i++ {
-		bench.Write(buf[:32*1024])
-	}
+func BenchmarkHash32K(b *testing.B) {
+	benchmarkSize(b, 32*1024)
 }
 
 // Benchmark writes of 128KiB bytes.
-func BenchmarkWrite128K(b *testing.B) {
-	b.SetBytes(int64(len(buf)))
-	for i := 0; i < b.N; i++ {
-		bench.Write(buf)
-	}
+func BenchmarkHash128K(b *testing.B) {
+	benchmarkSize(b, 128*1024)
 }

compressAvx2_noasm.go

@@ -1,23 +0,0 @@
-//+build !amd64 noasm appengine
-
-/*
- * Minio Cloud Storage, (C) 2016 Minio, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package blake2b
-
-func compressAvx2(d *digest, p []uint8) {
-	compressGeneric(d, p)
-}

compressAvx_amd64.go

@@ -0,0 +1,40 @@
+//+build !noasm
+//+build !appengine
+
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package blake2b
+
+//go:noescape
+func blockAVXLoop(p []uint8, in, iv, t, f, shffle, out []uint64)
+
+func compressAVX(d *digest, p []uint8) {
+
+	in := make([]uint64, 8, 8)
+	out := make([]uint64, 8, 8)
+
+	shffle := make([]uint64, 2, 2)
+	// vector for PSHUFB instruction
+	shffle[0] = 0x0201000706050403
+	shffle[1] = 0x0a09080f0e0d0c0b
+
+	in[0], in[1], in[2], in[3], in[4], in[5], in[6], in[7] = d.h[0], d.h[1], d.h[2], d.h[3], d.h[4], d.h[5], d.h[6], d.h[7]
+
+	blockAVXLoop(p, in, iv[:], d.t[:], d.f[:], shffle, out)
+
+	d.h[0], d.h[1], d.h[2], d.h[3], d.h[4], d.h[5], d.h[6], d.h[7] = out[0], out[1], out[2], out[3], out[4], out[5], out[6], out[7]
+}

compress_amd64.go

@@ -1,6 +1,3 @@
-//+build !noasm
-//+build !appengine
-
 /*
  * Minio Cloud Storage, (C) 2016 Minio, Inc.
  *
@@ -19,34 +16,13 @@
 
 package blake2b
 
-//go:noescape
-func blockAVXLoop(p []uint8, in, iv, t, f, shffle, out []uint64)
-
-func compressAVX(d *digest, p []uint8) {
-
-	in := make([]uint64, 8, 8)
-	out := make([]uint64, 8, 8)
-
-	shffle := make([]uint64, 2, 2)
-	// vector for PSHUFB instruction
-	shffle[0] = 0x0201000706050403
-	shffle[1] = 0x0a09080f0e0d0c0b
-
-	in[0], in[1], in[2], in[3], in[4], in[5], in[6], in[7] = d.h[0], d.h[1], d.h[2], d.h[3], d.h[4], d.h[5], d.h[6], d.h[7]
-
-	blockAVXLoop(p, in, iv[:], d.t[:], d.f[:], shffle, out)
-
-	d.h[0], d.h[1], d.h[2], d.h[3], d.h[4], d.h[5], d.h[6], d.h[7] = out[0], out[1], out[2], out[3], out[4], out[5], out[6], out[7]
-}
-
 func compress(d *digest, p []uint8) {
 	// Verifies if AVX2 or AVX is available, use optimized code path.
 	if avx2 {
 		compressAVX2(d, p)
-		return
 	} else if avx {
 		compressAVX(d, p)
-		return
-	} // else { fallback to generic approach.
-	compressGeneric(d, p)
+	} else {
+		compressGeneric(d, p)
+	}
 }

cpuid.go

@@ -40,8 +40,8 @@ func haveAVX() bool {
 
 // haveAVX2 returns true if when there is AVX2 support
 func haveAVX2() bool {
-
 	mfi, _, _, _ := cpuid(0)
+
 	// Check AVX2, AVX2 requires OS support, but BMI1/2 don't.
 	if mfi >= 7 && haveAVX() {
 		_, ebx, _, _ := cpuidex(7, 0)