util/deephash: rely on direct memory hashing for primitive kinds (#5457)

Rather than separate functions to hash each kind,
just rely on the fact that these are direct memory hashable,
thus simplifying the code.

Signed-off-by: Joe Tsai <joetsai@digital-static.net>

util/deephash/deephash.go

@@ -24,7 +24,6 @@
 	"crypto/sha256"
 	"encoding/binary"
 	"encoding/hex"
-	"math"
 	"net/netip"
 	"reflect"
 	"sync"
@@ -238,46 +237,6 @@ func (ti *typeInfo) buildHashFuncOnce() {
 	ti.hashFuncLazy = genTypeHasher(ti)
 }
 
-func (h *hasher) hashBoolv(v addressableValue) {
-	var b byte
-	if v.Bool() {
-		b = 1
-	}
-	h.HashUint8(b)
-}
-
-func (h *hasher) hashUint8v(v addressableValue) {
-	h.HashUint8(uint8(v.Uint()))
-}
-
-func (h *hasher) hashInt8v(v addressableValue) {
-	h.HashUint8(uint8(v.Int()))
-}
-
-func (h *hasher) hashUint16v(v addressableValue) {
-	h.HashUint16(uint16(v.Uint()))
-}
-
-func (h *hasher) hashInt16v(v addressableValue) {
-	h.HashUint16(uint16(v.Int()))
-}
-
-func (h *hasher) hashUint32v(v addressableValue) {
-	h.HashUint32(uint32(v.Uint()))
-}
-
-func (h *hasher) hashInt32v(v addressableValue) {
-	h.HashUint32(uint32(v.Int()))
-}
-
-func (h *hasher) hashUint64v(v addressableValue) {
-	h.HashUint64(v.Uint())
-}
-
-func (h *hasher) hashInt64v(v addressableValue) {
-	h.HashUint64(uint64(v.Int()))
-}
-
 // fieldInfo describes a struct field.
 type fieldInfo struct {
 	index      int // index of field for reflect.Value.Field(n); -1 if invalid
@@ -358,33 +317,21 @@ func genHashPtrToMemoryRange(eleType reflect.Type) typeHasherFunc {
 
 func genTypeHasher(ti *typeInfo) typeHasherFunc {
 	t := ti.rtype
+
+	// Types with specific hashing.
+	switch t {
+	case timeTimeType:
+		return (*hasher).hashTimev
+	case netipAddrType:
+		return (*hasher).hashAddrv
+	}
+
+	// Types that can have their memory representation directly hashed.
+	if typeIsMemHashable(t) {
+		return makeMemHasher(t.Size())
+	}
+
 	switch t.Kind() {
-	case reflect.Bool:
-		return (*hasher).hashBoolv
-	case reflect.Int8:
-		return (*hasher).hashInt8v
-	case reflect.Int16:
-		return (*hasher).hashInt16v
-	case reflect.Int32:
-		return (*hasher).hashInt32v
-	case reflect.Int, reflect.Int64:
-		return (*hasher).hashInt64v
-	case reflect.Uint8:
-		return (*hasher).hashUint8v
-	case reflect.Uint16:
-		return (*hasher).hashUint16v
-	case reflect.Uint32:
-		return (*hasher).hashUint32v
-	case reflect.Uint, reflect.Uintptr, reflect.Uint64:
-		return (*hasher).hashUint64v
-	case reflect.Float32:
-		return (*hasher).hashFloat32v
-	case reflect.Float64:
-		return (*hasher).hashFloat64v
-	case reflect.Complex64:
-		return (*hasher).hashComplex64v
-	case reflect.Complex128:
-		return (*hasher).hashComplex128v
 	case reflect.String:
 		return (*hasher).hashString
 	case reflect.Slice:
@@ -399,14 +346,7 @@ func genTypeHasher(ti *typeInfo) typeHasherFunc {
 		eti := getTypeInfo(et)
 		return genHashArray(t, eti)
 	case reflect.Struct:
-		switch t {
-		case timeTimeType:
-			return (*hasher).hashTimev
-		case netipAddrType:
-			return (*hasher).hashAddrv
-		default:
 		return genHashStructFields(t)
-		}
 	case reflect.Map:
 		return func(h *hasher, v addressableValue) {
 			if v.IsNil() {
@@ -476,26 +416,6 @@ func (h *hasher) hashString(v addressableValue) {
 	h.HashString(s)
 }
 
-func (h *hasher) hashFloat32v(v addressableValue) {
-	h.HashUint32(math.Float32bits(float32(v.Float())))
-}
-
-func (h *hasher) hashFloat64v(v addressableValue) {
-	h.HashUint64(math.Float64bits(v.Float()))
-}
-
-func (h *hasher) hashComplex64v(v addressableValue) {
-	c := complex64(v.Complex())
-	h.HashUint32(math.Float32bits(real(c)))
-	h.HashUint32(math.Float32bits(imag(c)))
-}
-
-func (h *hasher) hashComplex128v(v addressableValue) {
-	c := v.Complex()
-	h.HashUint64(math.Float64bits(real(c)))
-	h.HashUint64(math.Float64bits(imag(c)))
-}
-
 // hashTimev hashes v, of kind time.Time.
 func (h *hasher) hashTimev(v addressableValue) {
 	// Include the zone offset (but not the name) to keep
@@ -531,6 +451,12 @@ func (h *hasher) hashAddrv(v addressableValue) {
 	}
 }
 
+func makeMemHasher(n uintptr) typeHasherFunc {
+	return func(h *hasher, v addressableValue) {
+		h.HashBytes(unsafe.Slice((*byte)(v.Addr().UnsafePointer()), n))
+	}
+}
+
 // hashSliceMem hashes v, of kind Slice, with a memhash-able element type.
 func (h *hasher) hashSliceMem(v addressableValue) {
 	vLen := v.Len()

util/deephash/deephash_test.go

@@ -11,6 +11,7 @@
 	"fmt"
 	"hash"
 	"math"
+	"math/bits"
 	"math/rand"
 	"net/netip"
 	"reflect"
@@ -342,6 +343,13 @@ func u8(n uint8) string   { return string([]byte{n}) }
 func u16(n uint16) string { return string(binary.LittleEndian.AppendUint16(nil, n)) }
 func u32(n uint32) string { return string(binary.LittleEndian.AppendUint32(nil, n)) }
 func u64(n uint64) string { return string(binary.LittleEndian.AppendUint64(nil, n)) }
+func ux(n uint) string {
+	if bits.UintSize == 32 {
+		return u32(uint32(n))
+	} else {
+		return u64(uint64(n))
+	}
+}
 
 func TestGetTypeHasher(t *testing.T) {
 	switch runtime.GOARCH {
@@ -367,12 +375,12 @@ func TestGetTypeHasher(t *testing.T) {
 		{
 			name: "int",
 			val:  int(1),
-			out:  "\x01\x00\x00\x00\x00\x00\x00\x00",
+			out:  ux(1),
 		},
 		{
 			name: "int_negative",
 			val:  int(-1),
-			out:  "\xff\xff\xff\xff\xff\xff\xff\xff",
+			out:  ux(math.MaxUint),
 		},
 		{
 			name: "int8",