Use encoding/binary instead of unsafe (fixes spaolacci#29)

This removes the incorrect unsafe usage, instead using the marshalling operations from encoding/binary. Obviously, it's a bit slower: benchmark old ns/op new ns/op delta Benchmark32/1-8 4.68 5.02 +7.26% Benchmark32/2-8 5.15 5.16 +0.19% Benchmark32/4-8 5.05 5.56 +10.10% Benchmark32/8-8 6.10 6.95 +13.93% Benchmark32/16-8 8.18 9.94 +21.52% Benchmark32/32-8 12.5 15.4 +23.20% Benchmark32/64-8 20.7 26.7 +28.99% Benchmark32/128-8 38.3 55.9 +45.95% Benchmark32/256-8 75.8 94.1 +24.14% Benchmark32/512-8 150 191 +27.33% Benchmark32/1024-8 299 375 +25.42% Benchmark32/2048-8 586 730 +24.57% Benchmark32/4096-8 1170 1450 +23.93% Benchmark32/8192-8 2347 2888 +23.05% BenchmarkPartial32/8-8 157 155 -1.27% BenchmarkPartial32/16-8 185 184 -0.54% BenchmarkPartial32/32-8 243 240 -1.23% BenchmarkPartial32/64-8 201 206 +2.49% BenchmarkPartial32/128-8 223 240 +7.62% Benchmark64/1-8 12.3 12.2 -0.81% Benchmark64/2-8 12.8 12.9 +0.78% Benchmark64/4-8 14.2 13.9 -2.11% Benchmark64/8-8 16.1 15.5 -3.73% Benchmark64/16-8 13.7 15.3 +11.68% Benchmark64/32-8 16.2 19.2 +18.52% Benchmark64/64-8 20.3 26.4 +30.05% Benchmark64/128-8 28.8 40.8 +41.67% Benchmark64/256-8 47.3 68.8 +45.45% Benchmark64/512-8 81.8 126 +54.03% Benchmark64/1024-8 151 242 +60.26% Benchmark64/2048-8 291 477 +63.92% Benchmark64/4096-8 566 948 +67.49% Benchmark64/8192-8 1115 1873 +67.98% Benchmark128/1-8 12.9 12.9 +0.00% Benchmark128/2-8 13.2 13.5 +2.27% Benchmark128/4-8 14.3 14.2 -0.70% Benchmark128/8-8 15.9 16.1 +1.26% Benchmark128/16-8 13.6 16.0 +17.65% Benchmark128/32-8 15.9 20.0 +25.79% Benchmark128/64-8 20.5 26.9 +31.22% Benchmark128/128-8 29.1 41.2 +41.58% Benchmark128/256-8 46.5 69.6 +49.68% Benchmark128/512-8 81.0 126 +55.56% Benchmark128/1024-8 150 244 +62.67% Benchmark128/2048-8 292 471 +61.30% Benchmark128/4096-8 566 921 +62.72% Benchmark128/8192-8 1115 1868 +67.53% Nonetheless, it's correct and doesn't crash.
calmh · Feb 26, 2020 · 74e9af8 · 74e9af8
1 parent 539464a
commit 74e9af8
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Showing 3 changed files with 18 additions and 12 deletions.
diff --git a/murmur128.go b/murmur128.go
@@ -2,9 +2,9 @@ package murmur3
 
 import (
 	//"encoding/binary"
+	"encoding/binary"
 	"hash"
 	"math/bits"
-	"unsafe"
 )
 
 const (
@@ -65,8 +65,8 @@ func (d *digest128) bmix(p []byte) (tail []byte) {
 
 	nblocks := len(p) / 16
 	for i := 0; i < nblocks; i++ {
-		t := (*[2]uint64)(unsafe.Pointer(&p[i*16]))
-		k1, k2 := t[0], t[1]
+		k1 := binary.LittleEndian.Uint64(p[i*16:])
+		k2 := binary.LittleEndian.Uint64(p[i*16+8:])
 
 		k1 *= c1_128
 		k1 = bits.RotateLeft64(k1, 31)

diff --git a/murmur32.go b/murmur32.go
@@ -3,9 +3,9 @@ package murmur3
 // http://code.google.com/p/guava-libraries/source/browse/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
 
 import (
+	"encoding/binary"
 	"hash"
 	"math/bits"
-	"unsafe"
 )
 
 // Make sure interfaces are correctly implemented.
@@ -53,7 +53,7 @@ func (d *digest32) bmix(p []byte) (tail []byte) {
 
 	nblocks := len(p) / 4
 	for i := 0; i < nblocks; i++ {
-		k1 := *(*uint32)(unsafe.Pointer(&p[i*4]))
+		k1 := binary.LittleEndian.Uint32(p[i*4:])
 
 		k1 *= c1_32
 		k1 = bits.RotateLeft32(k1, 15)
@@ -115,13 +115,8 @@ func Sum32WithSeed(data []byte, seed uint32) uint32 {
 	h1 := seed
 
 	nblocks := len(data) / 4
-	var p uintptr
-	if len(data) > 0 {
-		p = uintptr(unsafe.Pointer(&data[0]))
-	}
-	p1 := p + uintptr(4*nblocks)
-	for ; p < p1; p += 4 {
-		k1 := *(*uint32)(unsafe.Pointer(p))
+	for i := 0; i < nblocks; i++ {
+		k1 := binary.LittleEndian.Uint32(data[i*4:])
 
 		k1 *= c1_32
 		k1 = bits.RotateLeft32(k1, 15)

diff --git a/murmur_test.go b/murmur_test.go
@@ -187,3 +187,14 @@ func Benchmark128(b *testing.B) {
 		})
 	}
 }
+
+func TestUnalignedWrite(t *testing.T) {
+	// Causes "fatal error: checkptr: unsafe pointer conversion" for unsafe
+	// pointer conversions in Go 1.14+
+	b := make([]byte, 128)
+	for i := 0; i < 16; i++ {
+		Sum32(b[i:])
+		Sum64(b[i:])
+		Sum128(b[i:])
+	}
+}