From ccd992355df7192993c666236047820244914598 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Tue, 16 Apr 2024 21:19:13 +0200 Subject: Adding upstream version 1.21.8. Signed-off-by: Daniel Baumann --- src/runtime/alg.go | 354 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 354 insertions(+) create mode 100644 src/runtime/alg.go (limited to 'src/runtime/alg.go') diff --git a/src/runtime/alg.go b/src/runtime/alg.go new file mode 100644 index 0000000..a1f683f --- /dev/null +++ b/src/runtime/alg.go @@ -0,0 +1,354 @@ +// 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(fastrand())) // 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(fastrand())) // 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())) + } +} + +//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 + } + getRandomData((*[len(hashkey) * goarch.PtrSize]byte)(unsafe.Pointer(&hashkey))[:]) + hashkey[0] |= 1 // make sure these numbers are odd + hashkey[1] |= 1 + hashkey[2] |= 1 + hashkey[3] |= 1 +} + +func initAlgAES() { + useAeshash = true + // Initialize with random data so hash collisions will be hard to engineer. + getRandomData(aeskeysched[:]) +} + +// 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 +} -- cgit v1.2.3