// 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/cpu" "internal/goarch" "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 := 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 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 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) } } 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. 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_ & kindMask { case kindFloat32: return f32hash(p, h) case kindFloat64: return f64hash(p, h) case kindComplex64: return c64hash(p, h) case kindComplex128: return c128hash(p, h) case kindString: return strhash(p, h) case kindInterface: i := (*interfacetype)(unsafe.Pointer(t)) if len(i.Methods) == 0 { return nilinterhash(p, h) } return interhash(p, h) case kindArray: 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 kindStruct: 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())) } } func mapKeyError(t *maptype, p unsafe.Pointer) error { if !t.HashMightPanic() { return nil } return mapKeyError2(t.Key, p) } func mapKeyError2(t *_type, p unsafe.Pointer) error { if t.TFlag&abi.TFlagRegularMemory != 0 { return nil } switch t.Kind_ & kindMask { case kindFloat32, kindFloat64, kindComplex64, kindComplex128, kindString: return nil case kindInterface: i := (*interfacetype)(unsafe.Pointer(t)) var t *_type var pdata *unsafe.Pointer if len(i.Methods) == 0 { a := (*eface)(p) t = a._type if t == nil { return nil } pdata = &a.data } else { a := (*iface)(p) if a.tab == nil { return nil } t = a.tab._type pdata = &a.data } if t.Equal == nil { return errorString("hash of unhashable type " + toRType(t).string()) } if isDirectIface(t) { return mapKeyError2(t, unsafe.Pointer(pdata)) } else { return mapKeyError2(t, *pdata) } case kindArray: a := (*arraytype)(unsafe.Pointer(t)) for i := uintptr(0); i < a.Len; i++ { if err := mapKeyError2(a.Elem, add(p, i*a.Elem.Size_)); err != nil { return err } } return nil case kindStruct: s := (*structtype)(unsafe.Pointer(t)) for _, f := range s.Fields { if f.Name.IsBlank() { continue } if err := mapKeyError2(f.Typ, add(p, f.Offset)); err != nil { return err } } return nil default: // Should never happen, keep this case for robustness. return 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) 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(rand()) | 1 // make sure these numbers are odd } } 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 uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24 } return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24 } func readUnaligned64(p unsafe.Pointer) uint64 { q := (*[8]byte)(p) if goarch.BigEndian { return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 | uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56 } return uint64(q[0]) | uint64(q[1])<<8 | uint64(q[2])<<16 | uint64(q[3])<<24 | uint64(q[4])<<32 | uint64(q[5])<<40 | uint64(q[6])<<48 | uint64(q[7])<<56 }