github.com/AESNooper/go/src@v0.0.0-20220218095104-b56a4ab1bbbb/runtime/alg.go (about) 1 // Copyright 2014 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package runtime 6 7 import ( 8 "internal/cpu" 9 "internal/goarch" 10 "unsafe" 11 ) 12 13 const ( 14 c0 = uintptr((8-goarch.PtrSize)/4*2860486313 + (goarch.PtrSize-4)/4*33054211828000289) 15 c1 = uintptr((8-goarch.PtrSize)/4*3267000013 + (goarch.PtrSize-4)/4*23344194077549503) 16 ) 17 18 func memhash0(p unsafe.Pointer, h uintptr) uintptr { 19 return h 20 } 21 22 func memhash8(p unsafe.Pointer, h uintptr) uintptr { 23 return memhash(p, h, 1) 24 } 25 26 func memhash16(p unsafe.Pointer, h uintptr) uintptr { 27 return memhash(p, h, 2) 28 } 29 30 func memhash128(p unsafe.Pointer, h uintptr) uintptr { 31 return memhash(p, h, 16) 32 } 33 34 //go:nosplit 35 func memhash_varlen(p unsafe.Pointer, h uintptr) uintptr { 36 ptr := getclosureptr() 37 size := *(*uintptr)(unsafe.Pointer(ptr + unsafe.Sizeof(h))) 38 return memhash(p, h, size) 39 } 40 41 // runtime variable to check if the processor we're running on 42 // actually supports the instructions used by the AES-based 43 // hash implementation. 44 var useAeshash bool 45 46 // in asm_*.s 47 func memhash(p unsafe.Pointer, h, s uintptr) uintptr 48 func memhash32(p unsafe.Pointer, h uintptr) uintptr 49 func memhash64(p unsafe.Pointer, h uintptr) uintptr 50 func strhash(p unsafe.Pointer, h uintptr) uintptr 51 52 func strhashFallback(a unsafe.Pointer, h uintptr) uintptr { 53 x := (*stringStruct)(a) 54 return memhashFallback(x.str, h, uintptr(x.len)) 55 } 56 57 // NOTE: Because NaN != NaN, a map can contain any 58 // number of (mostly useless) entries keyed with NaNs. 59 // To avoid long hash chains, we assign a random number 60 // as the hash value for a NaN. 61 62 func f32hash(p unsafe.Pointer, h uintptr) uintptr { 63 f := *(*float32)(p) 64 switch { 65 case f == 0: 66 return c1 * (c0 ^ h) // +0, -0 67 case f != f: 68 return c1 * (c0 ^ h ^ uintptr(fastrand())) // any kind of NaN 69 default: 70 return memhash(p, h, 4) 71 } 72 } 73 74 func f64hash(p unsafe.Pointer, h uintptr) uintptr { 75 f := *(*float64)(p) 76 switch { 77 case f == 0: 78 return c1 * (c0 ^ h) // +0, -0 79 case f != f: 80 return c1 * (c0 ^ h ^ uintptr(fastrand())) // any kind of NaN 81 default: 82 return memhash(p, h, 8) 83 } 84 } 85 86 func c64hash(p unsafe.Pointer, h uintptr) uintptr { 87 x := (*[2]float32)(p) 88 return f32hash(unsafe.Pointer(&x[1]), f32hash(unsafe.Pointer(&x[0]), h)) 89 } 90 91 func c128hash(p unsafe.Pointer, h uintptr) uintptr { 92 x := (*[2]float64)(p) 93 return f64hash(unsafe.Pointer(&x[1]), f64hash(unsafe.Pointer(&x[0]), h)) 94 } 95 96 func interhash(p unsafe.Pointer, h uintptr) uintptr { 97 a := (*iface)(p) 98 tab := a.tab 99 if tab == nil { 100 return h 101 } 102 t := tab._type 103 if t.equal == nil { 104 // Check hashability here. We could do this check inside 105 // typehash, but we want to report the topmost type in 106 // the error text (e.g. in a struct with a field of slice type 107 // we want to report the struct, not the slice). 108 panic(errorString("hash of unhashable type " + t.string())) 109 } 110 if isDirectIface(t) { 111 return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0) 112 } else { 113 return c1 * typehash(t, a.data, h^c0) 114 } 115 } 116 117 func nilinterhash(p unsafe.Pointer, h uintptr) uintptr { 118 a := (*eface)(p) 119 t := a._type 120 if t == nil { 121 return h 122 } 123 if t.equal == nil { 124 // See comment in interhash above. 125 panic(errorString("hash of unhashable type " + t.string())) 126 } 127 if isDirectIface(t) { 128 return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0) 129 } else { 130 return c1 * typehash(t, a.data, h^c0) 131 } 132 } 133 134 // typehash computes the hash of the object of type t at address p. 135 // h is the seed. 136 // This function is seldom used. Most maps use for hashing either 137 // fixed functions (e.g. f32hash) or compiler-generated functions 138 // (e.g. for a type like struct { x, y string }). This implementation 139 // is slower but more general and is used for hashing interface types 140 // (called from interhash or nilinterhash, above) or for hashing in 141 // maps generated by reflect.MapOf (reflect_typehash, below). 142 // Note: this function must match the compiler generated 143 // functions exactly. See issue 37716. 144 func typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr { 145 if t.tflag&tflagRegularMemory != 0 { 146 // Handle ptr sizes specially, see issue 37086. 147 switch t.size { 148 case 4: 149 return memhash32(p, h) 150 case 8: 151 return memhash64(p, h) 152 default: 153 return memhash(p, h, t.size) 154 } 155 } 156 switch t.kind & kindMask { 157 case kindFloat32: 158 return f32hash(p, h) 159 case kindFloat64: 160 return f64hash(p, h) 161 case kindComplex64: 162 return c64hash(p, h) 163 case kindComplex128: 164 return c128hash(p, h) 165 case kindString: 166 return strhash(p, h) 167 case kindInterface: 168 i := (*interfacetype)(unsafe.Pointer(t)) 169 if len(i.mhdr) == 0 { 170 return nilinterhash(p, h) 171 } 172 return interhash(p, h) 173 case kindArray: 174 a := (*arraytype)(unsafe.Pointer(t)) 175 for i := uintptr(0); i < a.len; i++ { 176 h = typehash(a.elem, add(p, i*a.elem.size), h) 177 } 178 return h 179 case kindStruct: 180 s := (*structtype)(unsafe.Pointer(t)) 181 for _, f := range s.fields { 182 if f.name.isBlank() { 183 continue 184 } 185 h = typehash(f.typ, add(p, f.offset()), h) 186 } 187 return h 188 default: 189 // Should never happen, as typehash should only be called 190 // with comparable types. 191 panic(errorString("hash of unhashable type " + t.string())) 192 } 193 } 194 195 //go:linkname reflect_typehash reflect.typehash 196 func reflect_typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr { 197 return typehash(t, p, h) 198 } 199 200 func memequal0(p, q unsafe.Pointer) bool { 201 return true 202 } 203 func memequal8(p, q unsafe.Pointer) bool { 204 return *(*int8)(p) == *(*int8)(q) 205 } 206 func memequal16(p, q unsafe.Pointer) bool { 207 return *(*int16)(p) == *(*int16)(q) 208 } 209 func memequal32(p, q unsafe.Pointer) bool { 210 return *(*int32)(p) == *(*int32)(q) 211 } 212 func memequal64(p, q unsafe.Pointer) bool { 213 return *(*int64)(p) == *(*int64)(q) 214 } 215 func memequal128(p, q unsafe.Pointer) bool { 216 return *(*[2]int64)(p) == *(*[2]int64)(q) 217 } 218 func f32equal(p, q unsafe.Pointer) bool { 219 return *(*float32)(p) == *(*float32)(q) 220 } 221 func f64equal(p, q unsafe.Pointer) bool { 222 return *(*float64)(p) == *(*float64)(q) 223 } 224 func c64equal(p, q unsafe.Pointer) bool { 225 return *(*complex64)(p) == *(*complex64)(q) 226 } 227 func c128equal(p, q unsafe.Pointer) bool { 228 return *(*complex128)(p) == *(*complex128)(q) 229 } 230 func strequal(p, q unsafe.Pointer) bool { 231 return *(*string)(p) == *(*string)(q) 232 } 233 func interequal(p, q unsafe.Pointer) bool { 234 x := *(*iface)(p) 235 y := *(*iface)(q) 236 return x.tab == y.tab && ifaceeq(x.tab, x.data, y.data) 237 } 238 func nilinterequal(p, q unsafe.Pointer) bool { 239 x := *(*eface)(p) 240 y := *(*eface)(q) 241 return x._type == y._type && efaceeq(x._type, x.data, y.data) 242 } 243 func efaceeq(t *_type, x, y unsafe.Pointer) bool { 244 if t == nil { 245 return true 246 } 247 eq := t.equal 248 if eq == nil { 249 panic(errorString("comparing uncomparable type " + t.string())) 250 } 251 if isDirectIface(t) { 252 // Direct interface types are ptr, chan, map, func, and single-element structs/arrays thereof. 253 // Maps and funcs are not comparable, so they can't reach here. 254 // Ptrs, chans, and single-element items can be compared directly using ==. 255 return x == y 256 } 257 return eq(x, y) 258 } 259 func ifaceeq(tab *itab, x, y unsafe.Pointer) bool { 260 if tab == nil { 261 return true 262 } 263 t := tab._type 264 eq := t.equal 265 if eq == nil { 266 panic(errorString("comparing uncomparable type " + t.string())) 267 } 268 if isDirectIface(t) { 269 // See comment in efaceeq. 270 return x == y 271 } 272 return eq(x, y) 273 } 274 275 // Testing adapters for hash quality tests (see hash_test.go) 276 func stringHash(s string, seed uintptr) uintptr { 277 return strhash(noescape(unsafe.Pointer(&s)), seed) 278 } 279 280 func bytesHash(b []byte, seed uintptr) uintptr { 281 s := (*slice)(unsafe.Pointer(&b)) 282 return memhash(s.array, seed, uintptr(s.len)) 283 } 284 285 func int32Hash(i uint32, seed uintptr) uintptr { 286 return memhash32(noescape(unsafe.Pointer(&i)), seed) 287 } 288 289 func int64Hash(i uint64, seed uintptr) uintptr { 290 return memhash64(noescape(unsafe.Pointer(&i)), seed) 291 } 292 293 func efaceHash(i interface{}, seed uintptr) uintptr { 294 return nilinterhash(noescape(unsafe.Pointer(&i)), seed) 295 } 296 297 func ifaceHash(i interface { 298 F() 299 }, seed uintptr) uintptr { 300 return interhash(noescape(unsafe.Pointer(&i)), seed) 301 } 302 303 const hashRandomBytes = goarch.PtrSize / 4 * 64 304 305 // used in asm_{386,amd64,arm64}.s to seed the hash function 306 var aeskeysched [hashRandomBytes]byte 307 308 // used in hash{32,64}.go to seed the hash function 309 var hashkey [4]uintptr 310 311 func alginit() { 312 // Install AES hash algorithms if the instructions needed are present. 313 if (GOARCH == "386" || GOARCH == "amd64") && 314 cpu.X86.HasAES && // AESENC 315 cpu.X86.HasSSSE3 && // PSHUFB 316 cpu.X86.HasSSE41 { // PINSR{D,Q} 317 initAlgAES() 318 return 319 } 320 if GOARCH == "arm64" && cpu.ARM64.HasAES { 321 initAlgAES() 322 return 323 } 324 getRandomData((*[len(hashkey) * goarch.PtrSize]byte)(unsafe.Pointer(&hashkey))[:]) 325 hashkey[0] |= 1 // make sure these numbers are odd 326 hashkey[1] |= 1 327 hashkey[2] |= 1 328 hashkey[3] |= 1 329 } 330 331 func initAlgAES() { 332 useAeshash = true 333 // Initialize with random data so hash collisions will be hard to engineer. 334 getRandomData(aeskeysched[:]) 335 } 336 337 // Note: These routines perform the read with a native endianness. 338 func readUnaligned32(p unsafe.Pointer) uint32 { 339 q := (*[4]byte)(p) 340 if goarch.BigEndian { 341 return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24 342 } 343 return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24 344 } 345 346 func readUnaligned64(p unsafe.Pointer) uint64 { 347 q := (*[8]byte)(p) 348 if goarch.BigEndian { 349 return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 | 350 uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56 351 } 352 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])<<56 353 }