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 "runtime/internal/sys" 10 "unsafe" 11 ) 12 13 const ( 14 c0 = uintptr((8-sys.PtrSize)/4*2860486313 + (sys.PtrSize-4)/4*33054211828000289) 15 c1 = uintptr((8-sys.PtrSize)/4*3267000013 + (sys.PtrSize-4)/4*23344194077549503) 16 ) 17 18 // type algorithms - known to compiler 19 const ( 20 alg_NOEQ = iota 21 alg_MEM0 22 alg_MEM8 23 alg_MEM16 24 alg_MEM32 25 alg_MEM64 26 alg_MEM128 27 alg_STRING 28 alg_INTER 29 alg_NILINTER 30 alg_FLOAT32 31 alg_FLOAT64 32 alg_CPLX64 33 alg_CPLX128 34 alg_max 35 ) 36 37 // typeAlg is also copied/used in reflect/type.go. 38 // keep them in sync. 39 type typeAlg struct { 40 // function for hashing objects of this type 41 // (ptr to object, seed) -> hash 42 hash func(unsafe.Pointer, uintptr) uintptr 43 // function for comparing objects of this type 44 // (ptr to object A, ptr to object B) -> ==? 45 equal func(unsafe.Pointer, unsafe.Pointer) bool 46 } 47 48 func memhash0(p unsafe.Pointer, h uintptr) uintptr { 49 return h 50 } 51 52 func memhash8(p unsafe.Pointer, h uintptr) uintptr { 53 return memhash(p, h, 1) 54 } 55 56 func memhash16(p unsafe.Pointer, h uintptr) uintptr { 57 return memhash(p, h, 2) 58 } 59 60 func memhash128(p unsafe.Pointer, h uintptr) uintptr { 61 return memhash(p, h, 16) 62 } 63 64 //go:nosplit 65 func memhash_varlen(p unsafe.Pointer, h uintptr) uintptr { 66 ptr := getclosureptr() 67 size := *(*uintptr)(unsafe.Pointer(ptr + unsafe.Sizeof(h))) 68 return memhash(p, h, size) 69 } 70 71 var algarray = [alg_max]typeAlg{ 72 alg_NOEQ: {nil, nil}, 73 alg_MEM0: {memhash0, memequal0}, 74 alg_MEM8: {memhash8, memequal8}, 75 alg_MEM16: {memhash16, memequal16}, 76 alg_MEM32: {memhash32, memequal32}, 77 alg_MEM64: {memhash64, memequal64}, 78 alg_MEM128: {memhash128, memequal128}, 79 alg_STRING: {strhash, strequal}, 80 alg_INTER: {interhash, interequal}, 81 alg_NILINTER: {nilinterhash, nilinterequal}, 82 alg_FLOAT32: {f32hash, f32equal}, 83 alg_FLOAT64: {f64hash, f64equal}, 84 alg_CPLX64: {c64hash, c64equal}, 85 alg_CPLX128: {c128hash, c128equal}, 86 } 87 88 var useAeshash bool 89 90 // in asm_*.s 91 func aeshash(p unsafe.Pointer, h, s uintptr) uintptr 92 func aeshash32(p unsafe.Pointer, h uintptr) uintptr 93 func aeshash64(p unsafe.Pointer, h uintptr) uintptr 94 func aeshashstr(p unsafe.Pointer, h uintptr) uintptr 95 96 func strhash(a unsafe.Pointer, h uintptr) uintptr { 97 x := (*stringStruct)(a) 98 return memhash(x.str, h, uintptr(x.len)) 99 } 100 101 // NOTE: Because NaN != NaN, a map can contain any 102 // number of (mostly useless) entries keyed with NaNs. 103 // To avoid long hash chains, we assign a random number 104 // as the hash value for a NaN. 105 106 func f32hash(p unsafe.Pointer, h uintptr) uintptr { 107 f := *(*float32)(p) 108 switch { 109 case f == 0: 110 return c1 * (c0 ^ h) // +0, -0 111 case f != f: 112 return c1 * (c0 ^ h ^ uintptr(fastrand())) // any kind of NaN 113 default: 114 return memhash(p, h, 4) 115 } 116 } 117 118 func f64hash(p unsafe.Pointer, h uintptr) uintptr { 119 f := *(*float64)(p) 120 switch { 121 case f == 0: 122 return c1 * (c0 ^ h) // +0, -0 123 case f != f: 124 return c1 * (c0 ^ h ^ uintptr(fastrand())) // any kind of NaN 125 default: 126 return memhash(p, h, 8) 127 } 128 } 129 130 func c64hash(p unsafe.Pointer, h uintptr) uintptr { 131 x := (*[2]float32)(p) 132 return f32hash(unsafe.Pointer(&x[1]), f32hash(unsafe.Pointer(&x[0]), h)) 133 } 134 135 func c128hash(p unsafe.Pointer, h uintptr) uintptr { 136 x := (*[2]float64)(p) 137 return f64hash(unsafe.Pointer(&x[1]), f64hash(unsafe.Pointer(&x[0]), h)) 138 } 139 140 func interhash(p unsafe.Pointer, h uintptr) uintptr { 141 a := (*iface)(p) 142 tab := a.tab 143 if tab == nil { 144 return h 145 } 146 t := tab._type 147 fn := t.alg.hash 148 if fn == nil { 149 panic(errorString("hash of unhashable type " + t.string())) 150 } 151 if isDirectIface(t) { 152 return c1 * fn(unsafe.Pointer(&a.data), h^c0) 153 } else { 154 return c1 * fn(a.data, h^c0) 155 } 156 } 157 158 func nilinterhash(p unsafe.Pointer, h uintptr) uintptr { 159 a := (*eface)(p) 160 t := a._type 161 if t == nil { 162 return h 163 } 164 fn := t.alg.hash 165 if fn == nil { 166 panic(errorString("hash of unhashable type " + t.string())) 167 } 168 if isDirectIface(t) { 169 return c1 * fn(unsafe.Pointer(&a.data), h^c0) 170 } else { 171 return c1 * fn(a.data, h^c0) 172 } 173 } 174 175 func memequal0(p, q unsafe.Pointer) bool { 176 return true 177 } 178 func memequal8(p, q unsafe.Pointer) bool { 179 return *(*int8)(p) == *(*int8)(q) 180 } 181 func memequal16(p, q unsafe.Pointer) bool { 182 return *(*int16)(p) == *(*int16)(q) 183 } 184 func memequal32(p, q unsafe.Pointer) bool { 185 return *(*int32)(p) == *(*int32)(q) 186 } 187 func memequal64(p, q unsafe.Pointer) bool { 188 return *(*int64)(p) == *(*int64)(q) 189 } 190 func memequal128(p, q unsafe.Pointer) bool { 191 return *(*[2]int64)(p) == *(*[2]int64)(q) 192 } 193 func f32equal(p, q unsafe.Pointer) bool { 194 return *(*float32)(p) == *(*float32)(q) 195 } 196 func f64equal(p, q unsafe.Pointer) bool { 197 return *(*float64)(p) == *(*float64)(q) 198 } 199 func c64equal(p, q unsafe.Pointer) bool { 200 return *(*complex64)(p) == *(*complex64)(q) 201 } 202 func c128equal(p, q unsafe.Pointer) bool { 203 return *(*complex128)(p) == *(*complex128)(q) 204 } 205 func strequal(p, q unsafe.Pointer) bool { 206 return *(*string)(p) == *(*string)(q) 207 } 208 func interequal(p, q unsafe.Pointer) bool { 209 x := *(*iface)(p) 210 y := *(*iface)(q) 211 return x.tab == y.tab && ifaceeq(x.tab, x.data, y.data) 212 } 213 func nilinterequal(p, q unsafe.Pointer) bool { 214 x := *(*eface)(p) 215 y := *(*eface)(q) 216 return x._type == y._type && efaceeq(x._type, x.data, y.data) 217 } 218 func efaceeq(t *_type, x, y unsafe.Pointer) bool { 219 if t == nil { 220 return true 221 } 222 eq := t.alg.equal 223 if eq == nil { 224 panic(errorString("comparing uncomparable type " + t.string())) 225 } 226 if isDirectIface(t) { 227 // Direct interface types are ptr, chan, map, func, and single-element structs/arrays thereof. 228 // Maps and funcs are not comparable, so they can't reach here. 229 // Ptrs, chans, and single-element items can be compared directly using ==. 230 return x == y 231 } 232 return eq(x, y) 233 } 234 func ifaceeq(tab *itab, x, y unsafe.Pointer) bool { 235 if tab == nil { 236 return true 237 } 238 t := tab._type 239 eq := t.alg.equal 240 if eq == nil { 241 panic(errorString("comparing uncomparable type " + t.string())) 242 } 243 if isDirectIface(t) { 244 // See comment in efaceeq. 245 return x == y 246 } 247 return eq(x, y) 248 } 249 250 // Testing adapters for hash quality tests (see hash_test.go) 251 func stringHash(s string, seed uintptr) uintptr { 252 return algarray[alg_STRING].hash(noescape(unsafe.Pointer(&s)), seed) 253 } 254 255 func bytesHash(b []byte, seed uintptr) uintptr { 256 s := (*slice)(unsafe.Pointer(&b)) 257 return memhash(s.array, seed, uintptr(s.len)) 258 } 259 260 func int32Hash(i uint32, seed uintptr) uintptr { 261 return algarray[alg_MEM32].hash(noescape(unsafe.Pointer(&i)), seed) 262 } 263 264 func int64Hash(i uint64, seed uintptr) uintptr { 265 return algarray[alg_MEM64].hash(noescape(unsafe.Pointer(&i)), seed) 266 } 267 268 func efaceHash(i interface{}, seed uintptr) uintptr { 269 return algarray[alg_NILINTER].hash(noescape(unsafe.Pointer(&i)), seed) 270 } 271 272 func ifaceHash(i interface { 273 F() 274 }, seed uintptr) uintptr { 275 return algarray[alg_INTER].hash(noescape(unsafe.Pointer(&i)), seed) 276 } 277 278 const hashRandomBytes = sys.PtrSize / 4 * 64 279 280 // used in asm_{386,amd64,arm64}.s to seed the hash function 281 var aeskeysched [hashRandomBytes]byte 282 283 // used in hash{32,64}.go to seed the hash function 284 var hashkey [4]uintptr 285 286 func alginit() { 287 // Install AES hash algorithms if the instructions needed are present. 288 if (GOARCH == "386" || GOARCH == "amd64") && 289 GOOS != "nacl" && 290 cpu.X86.HasAES && // AESENC 291 cpu.X86.HasSSSE3 && // PSHUFB 292 cpu.X86.HasSSE41 { // PINSR{D,Q} 293 initAlgAES() 294 return 295 } 296 if GOARCH == "arm64" && cpu.ARM64.HasAES { 297 initAlgAES() 298 return 299 } 300 getRandomData((*[len(hashkey) * sys.PtrSize]byte)(unsafe.Pointer(&hashkey))[:]) 301 hashkey[0] |= 1 // make sure these numbers are odd 302 hashkey[1] |= 1 303 hashkey[2] |= 1 304 hashkey[3] |= 1 305 } 306 307 func initAlgAES() { 308 if GOOS == "aix" { 309 // runtime.algarray is immutable on AIX: see cmd/link/internal/ld/xcoff.go 310 return 311 } 312 useAeshash = true 313 algarray[alg_MEM32].hash = aeshash32 314 algarray[alg_MEM64].hash = aeshash64 315 algarray[alg_STRING].hash = aeshashstr 316 // Initialize with random data so hash collisions will be hard to engineer. 317 getRandomData(aeskeysched[:]) 318 } 319 320 // Note: These routines perform the read with an native endianness. 321 func readUnaligned32(p unsafe.Pointer) uint32 { 322 q := (*[4]byte)(p) 323 if sys.BigEndian { 324 return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24 325 } 326 return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24 327 } 328 329 func readUnaligned64(p unsafe.Pointer) uint64 { 330 q := (*[8]byte)(p) 331 if sys.BigEndian { 332 return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 | 333 uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56 334 } 335 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])<<56 336 } 337
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