1 files changed, 352 insertions, 0 deletions
diff --git a/src/runtime/alg.go b/src/runtime/alg.go
new file mode 100644
index 000000000..e9ed59503
--- /dev/null
+++ b/src/runtime/alg.go
@@ -0,0 +1,352 @@
+// 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 "unsafe"
+
+const (
+	c0 = uintptr((8-ptrSize)/4*2860486313 + (ptrSize-4)/4*33054211828000289)
+	c1 = uintptr((8-ptrSize)/4*3267000013 + (ptrSize-4)/4*23344194077549503)
+)
+
+// type algorithms - known to compiler
+const (
+	alg_MEM = iota
+	alg_MEM0
+	alg_MEM8
+	alg_MEM16
+	alg_MEM32
+	alg_MEM64
+	alg_MEM128
+	alg_NOEQ
+	alg_NOEQ0
+	alg_NOEQ8
+	alg_NOEQ16
+	alg_NOEQ32
+	alg_NOEQ64
+	alg_NOEQ128
+	alg_STRING
+	alg_INTER
+	alg_NILINTER
+	alg_SLICE
+	alg_FLOAT32
+	alg_FLOAT64
+	alg_CPLX64
+	alg_CPLX128
+	alg_max
+)
+
+type typeAlg struct {
+	// function for hashing objects of this type
+	// (ptr to object, size, seed) -> hash
+	hash func(unsafe.Pointer, uintptr, uintptr) uintptr
+	// function for comparing objects of this type
+	// (ptr to object A, ptr to object B, size) -> ==?
+	equal func(unsafe.Pointer, unsafe.Pointer, uintptr) bool
+}
+
+var algarray = [alg_max]typeAlg{
+	alg_MEM:      {memhash, memequal},
+	alg_MEM0:     {memhash, memequal0},
+	alg_MEM8:     {memhash, memequal8},
+	alg_MEM16:    {memhash, memequal16},
+	alg_MEM32:    {memhash, memequal32},
+	alg_MEM64:    {memhash, memequal64},
+	alg_MEM128:   {memhash, memequal128},
+	alg_NOEQ:     {nil, nil},
+	alg_NOEQ0:    {nil, nil},
+	alg_NOEQ8:    {nil, nil},
+	alg_NOEQ16:   {nil, nil},
+	alg_NOEQ32:   {nil, nil},
+	alg_NOEQ64:   {nil, nil},
+	alg_NOEQ128:  {nil, nil},
+	alg_STRING:   {strhash, strequal},
+	alg_INTER:    {interhash, interequal},
+	alg_NILINTER: {nilinterhash, nilinterequal},
+	alg_SLICE:    {nil, nil},
+	alg_FLOAT32:  {f32hash, f32equal},
+	alg_FLOAT64:  {f64hash, f64equal},
+	alg_CPLX64:   {c64hash, c64equal},
+	alg_CPLX128:  {c128hash, c128equal},
+}
+
+const nacl = GOOS == "nacl"
+
+var useAeshash bool
+
+// in asm_*.s
+func aeshash(p unsafe.Pointer, s, h uintptr) uintptr
+func aeshash32(p unsafe.Pointer, s, h uintptr) uintptr
+func aeshash64(p unsafe.Pointer, s, h uintptr) uintptr
+func aeshashstr(p unsafe.Pointer, s, h uintptr) uintptr
+
+func memhash(p unsafe.Pointer, s, h uintptr) uintptr {
+	if !nacl && useAeshash {
+		return aeshash(p, s, h)
+	}
+
+	h ^= c0
+	for s > 0 {
+		h = (h ^ uintptr(*(*byte)(p))) * c1
+		p = add(p, 1)
+		s--
+	}
+	return h
+}
+
+func strhash(a unsafe.Pointer, s, h uintptr) uintptr {
+	return memhash((*stringStruct)(a).str, uintptr(len(*(*string)(a))), h)
+}
+
+// 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, s, h uintptr) uintptr {
+	f := *(*float32)(p)
+	switch {
+	case f == 0:
+		return c1 * (c0 ^ h) // +0, -0
+	case f != f:
+		return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
+	default:
+		return memhash(p, 4, h)
+	}
+}
+
+func f64hash(p unsafe.Pointer, s, h uintptr) uintptr {
+	f := *(*float64)(p)
+	switch {
+	case f == 0:
+		return c1 * (c0 ^ h) // +0, -0
+	case f != f:
+		return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
+	default:
+		return memhash(p, 8, h)
+	}
+}
+
+func c64hash(p unsafe.Pointer, s, h uintptr) uintptr {
+	x := (*[2]float32)(p)
+	return f32hash(unsafe.Pointer(&x[1]), 4, f32hash(unsafe.Pointer(&x[0]), 4, h))
+}
+
+func c128hash(p unsafe.Pointer, s, h uintptr) uintptr {
+	x := (*[2]float64)(p)
+	return f64hash(unsafe.Pointer(&x[1]), 8, f64hash(unsafe.Pointer(&x[0]), 8, h))
+}
+
+func interhash(p unsafe.Pointer, s, h uintptr) uintptr {
+	a := (*iface)(p)
+	tab := a.tab
+	if tab == nil {
+		return h
+	}
+	t := tab._type
+	fn := goalg(t.alg).hash
+	if fn == nil {
+		panic(errorString("hash of unhashable type " + *t._string))
+	}
+	if isDirectIface(t) {
+		return c1 * fn(unsafe.Pointer(&a.data), uintptr(t.size), h^c0)
+	} else {
+		return c1 * fn(a.data, uintptr(t.size), h^c0)
+	}
+}
+
+func nilinterhash(p unsafe.Pointer, s, h uintptr) uintptr {
+	a := (*eface)(p)
+	t := a._type
+	if t == nil {
+		return h
+	}
+	fn := goalg(t.alg).hash
+	if fn == nil {
+		panic(errorString("hash of unhashable type " + *t._string))
+	}
+	if isDirectIface(t) {
+		return c1 * fn(unsafe.Pointer(&a.data), uintptr(t.size), h^c0)
+	} else {
+		return c1 * fn(a.data, uintptr(t.size), h^c0)
+	}
+}
+
+func memequal(p, q unsafe.Pointer, size uintptr) bool {
+	if p == q {
+		return true
+	}
+	return memeq(p, q, size)
+}
+
+func memequal0(p, q unsafe.Pointer, size uintptr) bool {
+	return true
+}
+func memequal8(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*int8)(p) == *(*int8)(q)
+}
+func memequal16(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*int16)(p) == *(*int16)(q)
+}
+func memequal32(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*int32)(p) == *(*int32)(q)
+}
+func memequal64(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*int64)(p) == *(*int64)(q)
+}
+func memequal128(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*[2]int64)(p) == *(*[2]int64)(q)
+}
+func f32equal(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*float32)(p) == *(*float32)(q)
+}
+func f64equal(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*float64)(p) == *(*float64)(q)
+}
+func c64equal(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*complex64)(p) == *(*complex64)(q)
+}
+func c128equal(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*complex128)(p) == *(*complex128)(q)
+}
+func strequal(p, q unsafe.Pointer, size uintptr) bool {
+	return *(*string)(p) == *(*string)(q)
+}
+func interequal(p, q unsafe.Pointer, size uintptr) bool {
+	return ifaceeq(*(*interface {
+		f()
+	})(p), *(*interface {
+		f()
+	})(q))
+}
+func nilinterequal(p, q unsafe.Pointer, size uintptr) bool {
+	return efaceeq(*(*interface{})(p), *(*interface{})(q))
+}
+func efaceeq(p, q interface{}) bool {
+	x := (*eface)(unsafe.Pointer(&p))
+	y := (*eface)(unsafe.Pointer(&q))
+	t := x._type
+	if t != y._type {
+		return false
+	}
+	if t == nil {
+		return true
+	}
+	eq := goalg(t.alg).equal
+	if eq == nil {
+		panic(errorString("comparing uncomparable type " + *t._string))
+	}
+	if isDirectIface(t) {
+		return eq(noescape(unsafe.Pointer(&x.data)), noescape(unsafe.Pointer(&y.data)), uintptr(t.size))
+	}
+	return eq(x.data, y.data, uintptr(t.size))
+}
+func ifaceeq(p, q interface {
+	f()
+}) bool {
+	x := (*iface)(unsafe.Pointer(&p))
+	y := (*iface)(unsafe.Pointer(&q))
+	xtab := x.tab
+	if xtab != y.tab {
+		return false
+	}
+	if xtab == nil {
+		return true
+	}
+	t := xtab._type
+	eq := goalg(t.alg).equal
+	if eq == nil {
+		panic(errorString("comparing uncomparable type " + *t._string))
+	}
+	if isDirectIface(t) {
+		return eq(noescape(unsafe.Pointer(&x.data)), noescape(unsafe.Pointer(&y.data)), uintptr(t.size))
+	}
+	return eq(x.data, y.data, uintptr(t.size))
+}
+
+// Testing adapters for hash quality tests (see hash_test.go)
+func haveGoodHash() bool {
+	return useAeshash
+}
+
+func stringHash(s string, seed uintptr) uintptr {
+	return algarray[alg_STRING].hash(noescape(unsafe.Pointer(&s)), unsafe.Sizeof(s), seed)
+}
+
+func bytesHash(b []byte, seed uintptr) uintptr {
+	s := (*sliceStruct)(unsafe.Pointer(&b))
+	return algarray[alg_MEM].hash(s.array, uintptr(s.len), seed)
+}
+
+func int32Hash(i uint32, seed uintptr) uintptr {
+	return algarray[alg_MEM32].hash(noescape(unsafe.Pointer(&i)), 4, seed)
+}
+
+func int64Hash(i uint64, seed uintptr) uintptr {
+	return algarray[alg_MEM64].hash(noescape(unsafe.Pointer(&i)), 8, seed)
+}
+
+func efaceHash(i interface{}, seed uintptr) uintptr {
+	return algarray[alg_NILINTER].hash(noescape(unsafe.Pointer(&i)), unsafe.Sizeof(i), seed)
+}
+
+func ifaceHash(i interface {
+	F()
+}, seed uintptr) uintptr {
+	return algarray[alg_INTER].hash(noescape(unsafe.Pointer(&i)), unsafe.Sizeof(i), seed)
+}
+
+// Testing adapter for memclr
+func memclrBytes(b []byte) {
+	s := (*sliceStruct)(unsafe.Pointer(&b))
+	memclr(s.array, uintptr(s.len))
+}
+
+// TODO(dvyukov): remove when Type is converted to Go and contains *typeAlg.
+func goalg(a unsafe.Pointer) *typeAlg {
+	return (*typeAlg)(a)
+}
+
+// used in asm_{386,amd64}.s
+const hashRandomBytes = 32
+
+var aeskeysched [hashRandomBytes]byte
+
+//go:noescape
+func get_random_data(rnd *unsafe.Pointer, n *int32)
+
+func init() {
+	if theGoos == "nacl" {
+		return
+	}
+
+	// Install aes hash algorithm if we have the instructions we need
+	if (cpuid_ecx&(1<<25)) != 0 && // aes (aesenc)
+		(cpuid_ecx&(1<<9)) != 0 && // sse3 (pshufb)
+		(cpuid_ecx&(1<<19)) != 0 { // sse4.1 (pinsr{d,q})
+		useAeshash = true
+		algarray[alg_MEM].hash = aeshash
+		algarray[alg_MEM8].hash = aeshash
+		algarray[alg_MEM16].hash = aeshash
+		algarray[alg_MEM32].hash = aeshash32
+		algarray[alg_MEM64].hash = aeshash64
+		algarray[alg_MEM128].hash = aeshash
+		algarray[alg_STRING].hash = aeshashstr
+		// Initialize with random data so hash collisions will be hard to engineer.
+		var rnd unsafe.Pointer
+		var n int32
+		get_random_data(&rnd, &n)
+		if n > hashRandomBytes {
+			n = hashRandomBytes
+		}
+		memmove(unsafe.Pointer(&aeskeysched[0]), rnd, uintptr(n))
+		if n < hashRandomBytes {
+			// Not very random, but better than nothing.
+			for t := nanotime(); n < hashRandomBytes; n++ {
+				aeskeysched[n] = byte(t >> uint(8*(n%8)))
+			}
+		}
+	}
+}