// Copyright 2014 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
import (
"internal/abi"
"internal/byteorder"
"internal/cpu"
"internal/goarch"
"internal/runtime/sys"
"unsafe"
)
const (
c0 = uintptr((8-goarch.PtrSize)/4*2860486313 + (goarch.PtrSize-4)/4*33054211828000289)
c1 = uintptr((8-goarch.PtrSize)/4*3267000013 + (goarch.PtrSize-4)/4*23344194077549503)
)
func memhash0(p unsafe.Pointer, h uintptr) uintptr {
return h
}
func memhash8(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 1)
}
func memhash16(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 2)
}
func memhash128(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 16)
}
//go:nosplit
func memhash_varlen(p unsafe.Pointer, h uintptr) uintptr {
ptr := sys.GetClosurePtr()
size := *(*uintptr)(unsafe.Pointer(ptr + unsafe.Sizeof(h)))
return memhash(p, h, size)
}
// runtime variable to check if the processor we're running on
// actually supports the instructions used by the AES-based
// hash implementation.
var useAeshash bool
// in asm_*.s
// memhash should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/aacfactory/fns
// - github.com/dgraph-io/ristretto
// - github.com/minio/simdjson-go
// - github.com/nbd-wtf/go-nostr
// - github.com/outcaste-io/ristretto
// - github.com/puzpuzpuz/xsync/v2
// - github.com/puzpuzpuz/xsync/v3
// - github.com/authzed/spicedb
// - github.com/pingcap/badger
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname memhash
func memhash(p unsafe.Pointer, h, s uintptr) uintptr
func memhash32(p unsafe.Pointer, h uintptr) uintptr
func memhash64(p unsafe.Pointer, h uintptr) uintptr
// strhash should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/aristanetworks/goarista
// - github.com/bytedance/sonic
// - github.com/bytedance/go-tagexpr/v2
// - github.com/cloudwego/dynamicgo
// - github.com/v2fly/v2ray-core/v5
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname strhash
func strhash(p unsafe.Pointer, h uintptr) uintptr
func strhashFallback(a unsafe.Pointer, h uintptr) uintptr {
x := (*stringStruct)(a)
return memhashFallback(x.str, h, uintptr(x.len))
}
// NOTE: Because NaN != NaN, a map can contain any
// number of (mostly useless) entries keyed with NaNs.
// To avoid long hash chains, we assign a random number
// as the hash value for a NaN.
func f32hash(p unsafe.Pointer, h uintptr) uintptr {
f := *(*float32)(p)
switch {
case f == 0:
return c1 * (c0 ^ h) // +0, -0
case f != f:
return c1 * (c0 ^ h ^ uintptr(rand())) // any kind of NaN
default:
return memhash(p, h, 4)
}
}
func f64hash(p unsafe.Pointer, h uintptr) uintptr {
f := *(*float64)(p)
switch {
case f == 0:
return c1 * (c0 ^ h) // +0, -0
case f != f:
return c1 * (c0 ^ h ^ uintptr(rand())) // any kind of NaN
default:
return memhash(p, h, 8)
}
}
func c64hash(p unsafe.Pointer, h uintptr) uintptr {
x := (*[2]float32)(p)
return f32hash(unsafe.Pointer(&x[1]), f32hash(unsafe.Pointer(&x[0]), h))
}
func c128hash(p unsafe.Pointer, h uintptr) uintptr {
x := (*[2]float64)(p)
return f64hash(unsafe.Pointer(&x[1]), f64hash(unsafe.Pointer(&x[0]), h))
}
func interhash(p unsafe.Pointer, h uintptr) uintptr {
a := (*iface)(p)
tab := a.tab
if tab == nil {
return h
}
t := tab.Type
if t.Equal == nil {
// Check hashability here. We could do this check inside
// typehash, but we want to report the topmost type in
// the error text (e.g. in a struct with a field of slice type
// we want to report the struct, not the slice).
panic(errorString("hash of unhashable type " + toRType(t).string()))
}
if isDirectIface(t) {
return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0)
} else {
return c1 * typehash(t, a.data, h^c0)
}
}
// nilinterhash should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/anacrolix/stm
// - github.com/aristanetworks/goarista
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname nilinterhash
func nilinterhash(p unsafe.Pointer, h uintptr) uintptr {
a := (*eface)(p)
t := a._type
if t == nil {
return h
}
if t.Equal == nil {
// See comment in interhash above.
panic(errorString("hash of unhashable type " + toRType(t).string()))
}
if isDirectIface(t) {
return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0)
} else {
return c1 * typehash(t, a.data, h^c0)
}
}
// typehash computes the hash of the object of type t at address p.
// h is the seed.
// This function is seldom used. Most maps use for hashing either
// fixed functions (e.g. f32hash) or compiler-generated functions
// (e.g. for a type like struct { x, y string }). This implementation
// is slower but more general and is used for hashing interface types
// (called from interhash or nilinterhash, above) or for hashing in
// maps generated by reflect.MapOf (reflect_typehash, below).
// Note: this function must match the compiler generated
// functions exactly. See issue 37716.
//
// typehash should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/puzpuzpuz/xsync/v2
// - github.com/puzpuzpuz/xsync/v3
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname typehash
func typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
if t.TFlag&abi.TFlagRegularMemory != 0 {
// Handle ptr sizes specially, see issue 37086.
switch t.Size_ {
case 4:
return memhash32(p, h)
case 8:
return memhash64(p, h)
default:
return memhash(p, h, t.Size_)
}
}
switch t.Kind_ & abi.KindMask {
case abi.Float32:
return f32hash(p, h)
case abi.Float64:
return f64hash(p, h)
case abi.Complex64:
return c64hash(p, h)
case abi.Complex128:
return c128hash(p, h)
case abi.String:
return strhash(p, h)
case abi.Interface:
i := (*interfacetype)(unsafe.Pointer(t))
if len(i.Methods) == 0 {
return nilinterhash(p, h)
}
return interhash(p, h)
case abi.Array:
a := (*arraytype)(unsafe.Pointer(t))
for i := uintptr(0); i < a.Len; i++ {
h = typehash(a.Elem, add(p, i*a.Elem.Size_), h)
}
return h
case abi.Struct:
s := (*structtype)(unsafe.Pointer(t))
for _, f := range s.Fields {
if f.Name.IsBlank() {
continue
}
h = typehash(f.Typ, add(p, f.Offset), h)
}
return h
default:
// Should never happen, as typehash should only be called
// with comparable types.
panic(errorString("hash of unhashable type " + toRType(t).string()))
}
}
//go:linkname reflect_typehash reflect.typehash
func reflect_typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
return typehash(t, p, h)
}
func memequal0(p, q unsafe.Pointer) bool {
return true
}
func memequal8(p, q unsafe.Pointer) bool {
return *(*int8)(p) == *(*int8)(q)
}
func memequal16(p, q unsafe.Pointer) bool {
return *(*int16)(p) == *(*int16)(q)
}
func memequal32(p, q unsafe.Pointer) bool {
return *(*int32)(p) == *(*int32)(q)
}
func memequal64(p, q unsafe.Pointer) bool {
return *(*int64)(p) == *(*int64)(q)
}
func memequal128(p, q unsafe.Pointer) bool {
return *(*[2]int64)(p) == *(*[2]int64)(q)
}
func f32equal(p, q unsafe.Pointer) bool {
return *(*float32)(p) == *(*float32)(q)
}
func f64equal(p, q unsafe.Pointer) bool {
return *(*float64)(p) == *(*float64)(q)
}
func c64equal(p, q unsafe.Pointer) bool {
return *(*complex64)(p) == *(*complex64)(q)
}
func c128equal(p, q unsafe.Pointer) bool {
return *(*complex128)(p) == *(*complex128)(q)
}
func strequal(p, q unsafe.Pointer) bool {
return *(*string)(p) == *(*string)(q)
}
func interequal(p, q unsafe.Pointer) bool {
x := *(*iface)(p)
y := *(*iface)(q)
return x.tab == y.tab && ifaceeq(x.tab, x.data, y.data)
}
func nilinterequal(p, q unsafe.Pointer) bool {
x := *(*eface)(p)
y := *(*eface)(q)
return x._type == y._type && efaceeq(x._type, x.data, y.data)
}
func efaceeq(t *_type, x, y unsafe.Pointer) bool {
if t == nil {
return true
}
eq := t.Equal
if eq == nil {
panic(errorString("comparing uncomparable type " + toRType(t).string()))
}
if isDirectIface(t) {
// Direct interface types are ptr, chan, map, func, and single-element structs/arrays thereof.
// Maps and funcs are not comparable, so they can't reach here.
// Ptrs, chans, and single-element items can be compared directly using ==.
return x == y
}
return eq(x, y)
}
func ifaceeq(tab *itab, x, y unsafe.Pointer) bool {
if tab == nil {
return true
}
t := tab.Type
eq := t.Equal
if eq == nil {
panic(errorString("comparing uncomparable type " + toRType(t).string()))
}
if isDirectIface(t) {
// See comment in efaceeq.
return x == y
}
return eq(x, y)
}
// Testing adapters for hash quality tests (see hash_test.go)
//
// stringHash should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
// - github.com/k14s/starlark-go
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname stringHash
func stringHash(s string, seed uintptr) uintptr {
return strhash(noescape(unsafe.Pointer(&s)), seed)
}
func bytesHash(b []byte, seed uintptr) uintptr {
s := (*slice)(unsafe.Pointer(&b))
return memhash(s.array, seed, uintptr(s.len))
}
func int32Hash(i uint32, seed uintptr) uintptr {
return memhash32(noescape(unsafe.Pointer(&i)), seed)
}
func int64Hash(i uint64, seed uintptr) uintptr {
return memhash64(noescape(unsafe.Pointer(&i)), seed)
}
func efaceHash(i any, seed uintptr) uintptr {
return nilinterhash(noescape(unsafe.Pointer(&i)), seed)
}
func ifaceHash(i interface {
F()
}, seed uintptr) uintptr {
return interhash(noescape(unsafe.Pointer(&i)), seed)
}
const hashRandomBytes = goarch.PtrSize / 4 * 64
// used in asm_{386,amd64,arm64}.s to seed the hash function
var aeskeysched [hashRandomBytes]byte
// used in hash{32,64}.go to seed the hash function
var hashkey [4]uintptr
func alginit() {
// Install AES hash algorithms if the instructions needed are present.
if (GOARCH == "386" || GOARCH == "amd64") &&
cpu.X86.HasAES && // AESENC
cpu.X86.HasSSSE3 && // PSHUFB
cpu.X86.HasSSE41 { // PINSR{D,Q}
initAlgAES()
return
}
if GOARCH == "arm64" && cpu.ARM64.HasAES {
initAlgAES()
return
}
for i := range hashkey {
hashkey[i] = uintptr(bootstrapRand())
}
}
func initAlgAES() {
useAeshash = true
// Initialize with random data so hash collisions will be hard to engineer.
key := (*[hashRandomBytes / 8]uint64)(unsafe.Pointer(&aeskeysched))
for i := range key {
key[i] = bootstrapRand()
}
}
// Note: These routines perform the read with a native endianness.
func readUnaligned32(p unsafe.Pointer) uint32 {
q := (*[4]byte)(p)
if goarch.BigEndian {
return byteorder.BEUint32(q[:])
}
return byteorder.LEUint32(q[:])
}
func readUnaligned64(p unsafe.Pointer) uint64 {
q := (*[8]byte)(p)
if goarch.BigEndian {
return byteorder.BEUint64(q[:])
}
return byteorder.LEUint64(q[:])
}
