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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
commit43a123c1ae6613b3efeed291fa552ecd909d3acf (patch)
treefd92518b7024bc74031f78a1cf9e454b65e73665 /src/runtime/map.go
parentInitial commit. (diff)
downloadgolang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz
golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/runtime/map.go')
-rw-r--r--src/runtime/map.go1418
1 files changed, 1418 insertions, 0 deletions
diff --git a/src/runtime/map.go b/src/runtime/map.go
new file mode 100644
index 0000000..f546ce8
--- /dev/null
+++ b/src/runtime/map.go
@@ -0,0 +1,1418 @@
+// 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
+
+// This file contains the implementation of Go's map type.
+//
+// A map is just a hash table. The data is arranged
+// into an array of buckets. Each bucket contains up to
+// 8 key/elem pairs. The low-order bits of the hash are
+// used to select a bucket. Each bucket contains a few
+// high-order bits of each hash to distinguish the entries
+// within a single bucket.
+//
+// If more than 8 keys hash to a bucket, we chain on
+// extra buckets.
+//
+// When the hashtable grows, we allocate a new array
+// of buckets twice as big. Buckets are incrementally
+// copied from the old bucket array to the new bucket array.
+//
+// Map iterators walk through the array of buckets and
+// return the keys in walk order (bucket #, then overflow
+// chain order, then bucket index). To maintain iteration
+// semantics, we never move keys within their bucket (if
+// we did, keys might be returned 0 or 2 times). When
+// growing the table, iterators remain iterating through the
+// old table and must check the new table if the bucket
+// they are iterating through has been moved ("evacuated")
+// to the new table.
+
+// Picking loadFactor: too large and we have lots of overflow
+// buckets, too small and we waste a lot of space. I wrote
+// a simple program to check some stats for different loads:
+// (64-bit, 8 byte keys and elems)
+// loadFactor %overflow bytes/entry hitprobe missprobe
+// 4.00 2.13 20.77 3.00 4.00
+// 4.50 4.05 17.30 3.25 4.50
+// 5.00 6.85 14.77 3.50 5.00
+// 5.50 10.55 12.94 3.75 5.50
+// 6.00 15.27 11.67 4.00 6.00
+// 6.50 20.90 10.79 4.25 6.50
+// 7.00 27.14 10.15 4.50 7.00
+// 7.50 34.03 9.73 4.75 7.50
+// 8.00 41.10 9.40 5.00 8.00
+//
+// %overflow = percentage of buckets which have an overflow bucket
+// bytes/entry = overhead bytes used per key/elem pair
+// hitprobe = # of entries to check when looking up a present key
+// missprobe = # of entries to check when looking up an absent key
+//
+// Keep in mind this data is for maximally loaded tables, i.e. just
+// before the table grows. Typical tables will be somewhat less loaded.
+
+import (
+ "internal/abi"
+ "internal/goarch"
+ "runtime/internal/atomic"
+ "runtime/internal/math"
+ "unsafe"
+)
+
+const (
+ // Maximum number of key/elem pairs a bucket can hold.
+ bucketCntBits = 3
+ bucketCnt = 1 << bucketCntBits
+
+ // Maximum average load of a bucket that triggers growth is 6.5.
+ // Represent as loadFactorNum/loadFactorDen, to allow integer math.
+ loadFactorNum = 13
+ loadFactorDen = 2
+
+ // Maximum key or elem size to keep inline (instead of mallocing per element).
+ // Must fit in a uint8.
+ // Fast versions cannot handle big elems - the cutoff size for
+ // fast versions in cmd/compile/internal/gc/walk.go must be at most this elem.
+ maxKeySize = 128
+ maxElemSize = 128
+
+ // data offset should be the size of the bmap struct, but needs to be
+ // aligned correctly. For amd64p32 this means 64-bit alignment
+ // even though pointers are 32 bit.
+ dataOffset = unsafe.Offsetof(struct {
+ b bmap
+ v int64
+ }{}.v)
+
+ // Possible tophash values. We reserve a few possibilities for special marks.
+ // Each bucket (including its overflow buckets, if any) will have either all or none of its
+ // entries in the evacuated* states (except during the evacuate() method, which only happens
+ // during map writes and thus no one else can observe the map during that time).
+ emptyRest = 0 // this cell is empty, and there are no more non-empty cells at higher indexes or overflows.
+ emptyOne = 1 // this cell is empty
+ evacuatedX = 2 // key/elem is valid. Entry has been evacuated to first half of larger table.
+ evacuatedY = 3 // same as above, but evacuated to second half of larger table.
+ evacuatedEmpty = 4 // cell is empty, bucket is evacuated.
+ minTopHash = 5 // minimum tophash for a normal filled cell.
+
+ // flags
+ iterator = 1 // there may be an iterator using buckets
+ oldIterator = 2 // there may be an iterator using oldbuckets
+ hashWriting = 4 // a goroutine is writing to the map
+ sameSizeGrow = 8 // the current map growth is to a new map of the same size
+
+ // sentinel bucket ID for iterator checks
+ noCheck = 1<<(8*goarch.PtrSize) - 1
+)
+
+// isEmpty reports whether the given tophash array entry represents an empty bucket entry.
+func isEmpty(x uint8) bool {
+ return x <= emptyOne
+}
+
+// A header for a Go map.
+type hmap struct {
+ // Note: the format of the hmap is also encoded in cmd/compile/internal/reflectdata/reflect.go.
+ // Make sure this stays in sync with the compiler's definition.
+ count int // # live cells == size of map. Must be first (used by len() builtin)
+ flags uint8
+ B uint8 // log_2 of # of buckets (can hold up to loadFactor * 2^B items)
+ noverflow uint16 // approximate number of overflow buckets; see incrnoverflow for details
+ hash0 uint32 // hash seed
+
+ buckets unsafe.Pointer // array of 2^B Buckets. may be nil if count==0.
+ oldbuckets unsafe.Pointer // previous bucket array of half the size, non-nil only when growing
+ nevacuate uintptr // progress counter for evacuation (buckets less than this have been evacuated)
+
+ extra *mapextra // optional fields
+}
+
+// mapextra holds fields that are not present on all maps.
+type mapextra struct {
+ // If both key and elem do not contain pointers and are inline, then we mark bucket
+ // type as containing no pointers. This avoids scanning such maps.
+ // However, bmap.overflow is a pointer. In order to keep overflow buckets
+ // alive, we store pointers to all overflow buckets in hmap.extra.overflow and hmap.extra.oldoverflow.
+ // overflow and oldoverflow are only used if key and elem do not contain pointers.
+ // overflow contains overflow buckets for hmap.buckets.
+ // oldoverflow contains overflow buckets for hmap.oldbuckets.
+ // The indirection allows to store a pointer to the slice in hiter.
+ overflow *[]*bmap
+ oldoverflow *[]*bmap
+
+ // nextOverflow holds a pointer to a free overflow bucket.
+ nextOverflow *bmap
+}
+
+// A bucket for a Go map.
+type bmap struct {
+ // tophash generally contains the top byte of the hash value
+ // for each key in this bucket. If tophash[0] < minTopHash,
+ // tophash[0] is a bucket evacuation state instead.
+ tophash [bucketCnt]uint8
+ // Followed by bucketCnt keys and then bucketCnt elems.
+ // NOTE: packing all the keys together and then all the elems together makes the
+ // code a bit more complicated than alternating key/elem/key/elem/... but it allows
+ // us to eliminate padding which would be needed for, e.g., map[int64]int8.
+ // Followed by an overflow pointer.
+}
+
+// A hash iteration structure.
+// If you modify hiter, also change cmd/compile/internal/reflectdata/reflect.go
+// and reflect/value.go to match the layout of this structure.
+type hiter struct {
+ key unsafe.Pointer // Must be in first position. Write nil to indicate iteration end (see cmd/compile/internal/walk/range.go).
+ elem unsafe.Pointer // Must be in second position (see cmd/compile/internal/walk/range.go).
+ t *maptype
+ h *hmap
+ buckets unsafe.Pointer // bucket ptr at hash_iter initialization time
+ bptr *bmap // current bucket
+ overflow *[]*bmap // keeps overflow buckets of hmap.buckets alive
+ oldoverflow *[]*bmap // keeps overflow buckets of hmap.oldbuckets alive
+ startBucket uintptr // bucket iteration started at
+ offset uint8 // intra-bucket offset to start from during iteration (should be big enough to hold bucketCnt-1)
+ wrapped bool // already wrapped around from end of bucket array to beginning
+ B uint8
+ i uint8
+ bucket uintptr
+ checkBucket uintptr
+}
+
+// bucketShift returns 1<<b, optimized for code generation.
+func bucketShift(b uint8) uintptr {
+ // Masking the shift amount allows overflow checks to be elided.
+ return uintptr(1) << (b & (goarch.PtrSize*8 - 1))
+}
+
+// bucketMask returns 1<<b - 1, optimized for code generation.
+func bucketMask(b uint8) uintptr {
+ return bucketShift(b) - 1
+}
+
+// tophash calculates the tophash value for hash.
+func tophash(hash uintptr) uint8 {
+ top := uint8(hash >> (goarch.PtrSize*8 - 8))
+ if top < minTopHash {
+ top += minTopHash
+ }
+ return top
+}
+
+func evacuated(b *bmap) bool {
+ h := b.tophash[0]
+ return h > emptyOne && h < minTopHash
+}
+
+func (b *bmap) overflow(t *maptype) *bmap {
+ return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize))
+}
+
+func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
+ *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-goarch.PtrSize)) = ovf
+}
+
+func (b *bmap) keys() unsafe.Pointer {
+ return add(unsafe.Pointer(b), dataOffset)
+}
+
+// incrnoverflow increments h.noverflow.
+// noverflow counts the number of overflow buckets.
+// This is used to trigger same-size map growth.
+// See also tooManyOverflowBuckets.
+// To keep hmap small, noverflow is a uint16.
+// When there are few buckets, noverflow is an exact count.
+// When there are many buckets, noverflow is an approximate count.
+func (h *hmap) incrnoverflow() {
+ // We trigger same-size map growth if there are
+ // as many overflow buckets as buckets.
+ // We need to be able to count to 1<<h.B.
+ if h.B < 16 {
+ h.noverflow++
+ return
+ }
+ // Increment with probability 1/(1<<(h.B-15)).
+ // When we reach 1<<15 - 1, we will have approximately
+ // as many overflow buckets as buckets.
+ mask := uint32(1)<<(h.B-15) - 1
+ // Example: if h.B == 18, then mask == 7,
+ // and fastrand & 7 == 0 with probability 1/8.
+ if fastrand()&mask == 0 {
+ h.noverflow++
+ }
+}
+
+func (h *hmap) newoverflow(t *maptype, b *bmap) *bmap {
+ var ovf *bmap
+ if h.extra != nil && h.extra.nextOverflow != nil {
+ // We have preallocated overflow buckets available.
+ // See makeBucketArray for more details.
+ ovf = h.extra.nextOverflow
+ if ovf.overflow(t) == nil {
+ // We're not at the end of the preallocated overflow buckets. Bump the pointer.
+ h.extra.nextOverflow = (*bmap)(add(unsafe.Pointer(ovf), uintptr(t.bucketsize)))
+ } else {
+ // This is the last preallocated overflow bucket.
+ // Reset the overflow pointer on this bucket,
+ // which was set to a non-nil sentinel value.
+ ovf.setoverflow(t, nil)
+ h.extra.nextOverflow = nil
+ }
+ } else {
+ ovf = (*bmap)(newobject(t.bucket))
+ }
+ h.incrnoverflow()
+ if t.bucket.ptrdata == 0 {
+ h.createOverflow()
+ *h.extra.overflow = append(*h.extra.overflow, ovf)
+ }
+ b.setoverflow(t, ovf)
+ return ovf
+}
+
+func (h *hmap) createOverflow() {
+ if h.extra == nil {
+ h.extra = new(mapextra)
+ }
+ if h.extra.overflow == nil {
+ h.extra.overflow = new([]*bmap)
+ }
+}
+
+func makemap64(t *maptype, hint int64, h *hmap) *hmap {
+ if int64(int(hint)) != hint {
+ hint = 0
+ }
+ return makemap(t, int(hint), h)
+}
+
+// makemap_small implements Go map creation for make(map[k]v) and
+// make(map[k]v, hint) when hint is known to be at most bucketCnt
+// at compile time and the map needs to be allocated on the heap.
+func makemap_small() *hmap {
+ h := new(hmap)
+ h.hash0 = fastrand()
+ return h
+}
+
+// makemap implements Go map creation for make(map[k]v, hint).
+// If the compiler has determined that the map or the first bucket
+// can be created on the stack, h and/or bucket may be non-nil.
+// If h != nil, the map can be created directly in h.
+// If h.buckets != nil, bucket pointed to can be used as the first bucket.
+func makemap(t *maptype, hint int, h *hmap) *hmap {
+ mem, overflow := math.MulUintptr(uintptr(hint), t.bucket.size)
+ if overflow || mem > maxAlloc {
+ hint = 0
+ }
+
+ // initialize Hmap
+ if h == nil {
+ h = new(hmap)
+ }
+ h.hash0 = fastrand()
+
+ // Find the size parameter B which will hold the requested # of elements.
+ // For hint < 0 overLoadFactor returns false since hint < bucketCnt.
+ B := uint8(0)
+ for overLoadFactor(hint, B) {
+ B++
+ }
+ h.B = B
+
+ // allocate initial hash table
+ // if B == 0, the buckets field is allocated lazily later (in mapassign)
+ // If hint is large zeroing this memory could take a while.
+ if h.B != 0 {
+ var nextOverflow *bmap
+ h.buckets, nextOverflow = makeBucketArray(t, h.B, nil)
+ if nextOverflow != nil {
+ h.extra = new(mapextra)
+ h.extra.nextOverflow = nextOverflow
+ }
+ }
+
+ return h
+}
+
+// makeBucketArray initializes a backing array for map buckets.
+// 1<<b is the minimum number of buckets to allocate.
+// dirtyalloc should either be nil or a bucket array previously
+// allocated by makeBucketArray with the same t and b parameters.
+// If dirtyalloc is nil a new backing array will be alloced and
+// otherwise dirtyalloc will be cleared and reused as backing array.
+func makeBucketArray(t *maptype, b uint8, dirtyalloc unsafe.Pointer) (buckets unsafe.Pointer, nextOverflow *bmap) {
+ base := bucketShift(b)
+ nbuckets := base
+ // For small b, overflow buckets are unlikely.
+ // Avoid the overhead of the calculation.
+ if b >= 4 {
+ // Add on the estimated number of overflow buckets
+ // required to insert the median number of elements
+ // used with this value of b.
+ nbuckets += bucketShift(b - 4)
+ sz := t.bucket.size * nbuckets
+ up := roundupsize(sz)
+ if up != sz {
+ nbuckets = up / t.bucket.size
+ }
+ }
+
+ if dirtyalloc == nil {
+ buckets = newarray(t.bucket, int(nbuckets))
+ } else {
+ // dirtyalloc was previously generated by
+ // the above newarray(t.bucket, int(nbuckets))
+ // but may not be empty.
+ buckets = dirtyalloc
+ size := t.bucket.size * nbuckets
+ if t.bucket.ptrdata != 0 {
+ memclrHasPointers(buckets, size)
+ } else {
+ memclrNoHeapPointers(buckets, size)
+ }
+ }
+
+ if base != nbuckets {
+ // We preallocated some overflow buckets.
+ // To keep the overhead of tracking these overflow buckets to a minimum,
+ // we use the convention that if a preallocated overflow bucket's overflow
+ // pointer is nil, then there are more available by bumping the pointer.
+ // We need a safe non-nil pointer for the last overflow bucket; just use buckets.
+ nextOverflow = (*bmap)(add(buckets, base*uintptr(t.bucketsize)))
+ last := (*bmap)(add(buckets, (nbuckets-1)*uintptr(t.bucketsize)))
+ last.setoverflow(t, (*bmap)(buckets))
+ }
+ return buckets, nextOverflow
+}
+
+// mapaccess1 returns a pointer to h[key]. Never returns nil, instead
+// it will return a reference to the zero object for the elem type if
+// the key is not in the map.
+// NOTE: The returned pointer may keep the whole map live, so don't
+// hold onto it for very long.
+func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
+ if raceenabled && h != nil {
+ callerpc := getcallerpc()
+ pc := abi.FuncPCABIInternal(mapaccess1)
+ racereadpc(unsafe.Pointer(h), callerpc, pc)
+ raceReadObjectPC(t.key, key, callerpc, pc)
+ }
+ if msanenabled && h != nil {
+ msanread(key, t.key.size)
+ }
+ if asanenabled && h != nil {
+ asanread(key, t.key.size)
+ }
+ if h == nil || h.count == 0 {
+ if t.hashMightPanic() {
+ t.hasher(key, 0) // see issue 23734
+ }
+ return unsafe.Pointer(&zeroVal[0])
+ }
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map read and map write")
+ }
+ hash := t.hasher(key, uintptr(h.hash0))
+ m := bucketMask(h.B)
+ b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
+ if c := h.oldbuckets; c != nil {
+ if !h.sameSizeGrow() {
+ // There used to be half as many buckets; mask down one more power of two.
+ m >>= 1
+ }
+ oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
+ if !evacuated(oldb) {
+ b = oldb
+ }
+ }
+ top := tophash(hash)
+bucketloop:
+ for ; b != nil; b = b.overflow(t) {
+ for i := uintptr(0); i < bucketCnt; i++ {
+ if b.tophash[i] != top {
+ if b.tophash[i] == emptyRest {
+ break bucketloop
+ }
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ if t.indirectkey() {
+ k = *((*unsafe.Pointer)(k))
+ }
+ if t.key.equal(key, k) {
+ e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ if t.indirectelem() {
+ e = *((*unsafe.Pointer)(e))
+ }
+ return e
+ }
+ }
+ }
+ return unsafe.Pointer(&zeroVal[0])
+}
+
+func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
+ if raceenabled && h != nil {
+ callerpc := getcallerpc()
+ pc := abi.FuncPCABIInternal(mapaccess2)
+ racereadpc(unsafe.Pointer(h), callerpc, pc)
+ raceReadObjectPC(t.key, key, callerpc, pc)
+ }
+ if msanenabled && h != nil {
+ msanread(key, t.key.size)
+ }
+ if asanenabled && h != nil {
+ asanread(key, t.key.size)
+ }
+ if h == nil || h.count == 0 {
+ if t.hashMightPanic() {
+ t.hasher(key, 0) // see issue 23734
+ }
+ return unsafe.Pointer(&zeroVal[0]), false
+ }
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map read and map write")
+ }
+ hash := t.hasher(key, uintptr(h.hash0))
+ m := bucketMask(h.B)
+ b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
+ if c := h.oldbuckets; c != nil {
+ if !h.sameSizeGrow() {
+ // There used to be half as many buckets; mask down one more power of two.
+ m >>= 1
+ }
+ oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
+ if !evacuated(oldb) {
+ b = oldb
+ }
+ }
+ top := tophash(hash)
+bucketloop:
+ for ; b != nil; b = b.overflow(t) {
+ for i := uintptr(0); i < bucketCnt; i++ {
+ if b.tophash[i] != top {
+ if b.tophash[i] == emptyRest {
+ break bucketloop
+ }
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ if t.indirectkey() {
+ k = *((*unsafe.Pointer)(k))
+ }
+ if t.key.equal(key, k) {
+ e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ if t.indirectelem() {
+ e = *((*unsafe.Pointer)(e))
+ }
+ return e, true
+ }
+ }
+ }
+ return unsafe.Pointer(&zeroVal[0]), false
+}
+
+// returns both key and elem. Used by map iterator.
+func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer) {
+ if h == nil || h.count == 0 {
+ return nil, nil
+ }
+ hash := t.hasher(key, uintptr(h.hash0))
+ m := bucketMask(h.B)
+ b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
+ if c := h.oldbuckets; c != nil {
+ if !h.sameSizeGrow() {
+ // There used to be half as many buckets; mask down one more power of two.
+ m >>= 1
+ }
+ oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
+ if !evacuated(oldb) {
+ b = oldb
+ }
+ }
+ top := tophash(hash)
+bucketloop:
+ for ; b != nil; b = b.overflow(t) {
+ for i := uintptr(0); i < bucketCnt; i++ {
+ if b.tophash[i] != top {
+ if b.tophash[i] == emptyRest {
+ break bucketloop
+ }
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ if t.indirectkey() {
+ k = *((*unsafe.Pointer)(k))
+ }
+ if t.key.equal(key, k) {
+ e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ if t.indirectelem() {
+ e = *((*unsafe.Pointer)(e))
+ }
+ return k, e
+ }
+ }
+ }
+ return nil, nil
+}
+
+func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointer {
+ e := mapaccess1(t, h, key)
+ if e == unsafe.Pointer(&zeroVal[0]) {
+ return zero
+ }
+ return e
+}
+
+func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Pointer, bool) {
+ e := mapaccess1(t, h, key)
+ if e == unsafe.Pointer(&zeroVal[0]) {
+ return zero, false
+ }
+ return e, true
+}
+
+// Like mapaccess, but allocates a slot for the key if it is not present in the map.
+func mapassign(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
+ if h == nil {
+ panic(plainError("assignment to entry in nil map"))
+ }
+ if raceenabled {
+ callerpc := getcallerpc()
+ pc := abi.FuncPCABIInternal(mapassign)
+ racewritepc(unsafe.Pointer(h), callerpc, pc)
+ raceReadObjectPC(t.key, key, callerpc, pc)
+ }
+ if msanenabled {
+ msanread(key, t.key.size)
+ }
+ if asanenabled {
+ asanread(key, t.key.size)
+ }
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map writes")
+ }
+ hash := t.hasher(key, uintptr(h.hash0))
+
+ // Set hashWriting after calling t.hasher, since t.hasher may panic,
+ // in which case we have not actually done a write.
+ h.flags ^= hashWriting
+
+ if h.buckets == nil {
+ h.buckets = newobject(t.bucket) // newarray(t.bucket, 1)
+ }
+
+again:
+ bucket := hash & bucketMask(h.B)
+ if h.growing() {
+ growWork(t, h, bucket)
+ }
+ b := (*bmap)(add(h.buckets, bucket*uintptr(t.bucketsize)))
+ top := tophash(hash)
+
+ var inserti *uint8
+ var insertk unsafe.Pointer
+ var elem unsafe.Pointer
+bucketloop:
+ for {
+ for i := uintptr(0); i < bucketCnt; i++ {
+ if b.tophash[i] != top {
+ if isEmpty(b.tophash[i]) && inserti == nil {
+ inserti = &b.tophash[i]
+ insertk = add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ elem = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ }
+ if b.tophash[i] == emptyRest {
+ break bucketloop
+ }
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ if t.indirectkey() {
+ k = *((*unsafe.Pointer)(k))
+ }
+ if !t.key.equal(key, k) {
+ continue
+ }
+ // already have a mapping for key. Update it.
+ if t.needkeyupdate() {
+ typedmemmove(t.key, k, key)
+ }
+ elem = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ goto done
+ }
+ ovf := b.overflow(t)
+ if ovf == nil {
+ break
+ }
+ b = ovf
+ }
+
+ // Did not find mapping for key. Allocate new cell & add entry.
+
+ // If we hit the max load factor or we have too many overflow buckets,
+ // and we're not already in the middle of growing, start growing.
+ if !h.growing() && (overLoadFactor(h.count+1, h.B) || tooManyOverflowBuckets(h.noverflow, h.B)) {
+ hashGrow(t, h)
+ goto again // Growing the table invalidates everything, so try again
+ }
+
+ if inserti == nil {
+ // The current bucket and all the overflow buckets connected to it are full, allocate a new one.
+ newb := h.newoverflow(t, b)
+ inserti = &newb.tophash[0]
+ insertk = add(unsafe.Pointer(newb), dataOffset)
+ elem = add(insertk, bucketCnt*uintptr(t.keysize))
+ }
+
+ // store new key/elem at insert position
+ if t.indirectkey() {
+ kmem := newobject(t.key)
+ *(*unsafe.Pointer)(insertk) = kmem
+ insertk = kmem
+ }
+ if t.indirectelem() {
+ vmem := newobject(t.elem)
+ *(*unsafe.Pointer)(elem) = vmem
+ }
+ typedmemmove(t.key, insertk, key)
+ *inserti = top
+ h.count++
+
+done:
+ if h.flags&hashWriting == 0 {
+ fatal("concurrent map writes")
+ }
+ h.flags &^= hashWriting
+ if t.indirectelem() {
+ elem = *((*unsafe.Pointer)(elem))
+ }
+ return elem
+}
+
+func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
+ if raceenabled && h != nil {
+ callerpc := getcallerpc()
+ pc := abi.FuncPCABIInternal(mapdelete)
+ racewritepc(unsafe.Pointer(h), callerpc, pc)
+ raceReadObjectPC(t.key, key, callerpc, pc)
+ }
+ if msanenabled && h != nil {
+ msanread(key, t.key.size)
+ }
+ if asanenabled && h != nil {
+ asanread(key, t.key.size)
+ }
+ if h == nil || h.count == 0 {
+ if t.hashMightPanic() {
+ t.hasher(key, 0) // see issue 23734
+ }
+ return
+ }
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map writes")
+ }
+
+ hash := t.hasher(key, uintptr(h.hash0))
+
+ // Set hashWriting after calling t.hasher, since t.hasher may panic,
+ // in which case we have not actually done a write (delete).
+ h.flags ^= hashWriting
+
+ bucket := hash & bucketMask(h.B)
+ if h.growing() {
+ growWork(t, h, bucket)
+ }
+ b := (*bmap)(add(h.buckets, bucket*uintptr(t.bucketsize)))
+ bOrig := b
+ top := tophash(hash)
+search:
+ for ; b != nil; b = b.overflow(t) {
+ for i := uintptr(0); i < bucketCnt; i++ {
+ if b.tophash[i] != top {
+ if b.tophash[i] == emptyRest {
+ break search
+ }
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
+ k2 := k
+ if t.indirectkey() {
+ k2 = *((*unsafe.Pointer)(k2))
+ }
+ if !t.key.equal(key, k2) {
+ continue
+ }
+ // Only clear key if there are pointers in it.
+ if t.indirectkey() {
+ *(*unsafe.Pointer)(k) = nil
+ } else if t.key.ptrdata != 0 {
+ memclrHasPointers(k, t.key.size)
+ }
+ e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.elemsize))
+ if t.indirectelem() {
+ *(*unsafe.Pointer)(e) = nil
+ } else if t.elem.ptrdata != 0 {
+ memclrHasPointers(e, t.elem.size)
+ } else {
+ memclrNoHeapPointers(e, t.elem.size)
+ }
+ b.tophash[i] = emptyOne
+ // If the bucket now ends in a bunch of emptyOne states,
+ // change those to emptyRest states.
+ // It would be nice to make this a separate function, but
+ // for loops are not currently inlineable.
+ if i == bucketCnt-1 {
+ if b.overflow(t) != nil && b.overflow(t).tophash[0] != emptyRest {
+ goto notLast
+ }
+ } else {
+ if b.tophash[i+1] != emptyRest {
+ goto notLast
+ }
+ }
+ for {
+ b.tophash[i] = emptyRest
+ if i == 0 {
+ if b == bOrig {
+ break // beginning of initial bucket, we're done.
+ }
+ // Find previous bucket, continue at its last entry.
+ c := b
+ for b = bOrig; b.overflow(t) != c; b = b.overflow(t) {
+ }
+ i = bucketCnt - 1
+ } else {
+ i--
+ }
+ if b.tophash[i] != emptyOne {
+ break
+ }
+ }
+ notLast:
+ h.count--
+ // Reset the hash seed to make it more difficult for attackers to
+ // repeatedly trigger hash collisions. See issue 25237.
+ if h.count == 0 {
+ h.hash0 = fastrand()
+ }
+ break search
+ }
+ }
+
+ if h.flags&hashWriting == 0 {
+ fatal("concurrent map writes")
+ }
+ h.flags &^= hashWriting
+}
+
+// mapiterinit initializes the hiter struct used for ranging over maps.
+// The hiter struct pointed to by 'it' is allocated on the stack
+// by the compilers order pass or on the heap by reflect_mapiterinit.
+// Both need to have zeroed hiter since the struct contains pointers.
+func mapiterinit(t *maptype, h *hmap, it *hiter) {
+ if raceenabled && h != nil {
+ callerpc := getcallerpc()
+ racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiterinit))
+ }
+
+ it.t = t
+ if h == nil || h.count == 0 {
+ return
+ }
+
+ if unsafe.Sizeof(hiter{})/goarch.PtrSize != 12 {
+ throw("hash_iter size incorrect") // see cmd/compile/internal/reflectdata/reflect.go
+ }
+ it.h = h
+
+ // grab snapshot of bucket state
+ it.B = h.B
+ it.buckets = h.buckets
+ if t.bucket.ptrdata == 0 {
+ // Allocate the current slice and remember pointers to both current and old.
+ // This preserves all relevant overflow buckets alive even if
+ // the table grows and/or overflow buckets are added to the table
+ // while we are iterating.
+ h.createOverflow()
+ it.overflow = h.extra.overflow
+ it.oldoverflow = h.extra.oldoverflow
+ }
+
+ // decide where to start
+ var r uintptr
+ if h.B > 31-bucketCntBits {
+ r = uintptr(fastrand64())
+ } else {
+ r = uintptr(fastrand())
+ }
+ it.startBucket = r & bucketMask(h.B)
+ it.offset = uint8(r >> h.B & (bucketCnt - 1))
+
+ // iterator state
+ it.bucket = it.startBucket
+
+ // Remember we have an iterator.
+ // Can run concurrently with another mapiterinit().
+ if old := h.flags; old&(iterator|oldIterator) != iterator|oldIterator {
+ atomic.Or8(&h.flags, iterator|oldIterator)
+ }
+
+ mapiternext(it)
+}
+
+func mapiternext(it *hiter) {
+ h := it.h
+ if raceenabled {
+ callerpc := getcallerpc()
+ racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiternext))
+ }
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map iteration and map write")
+ }
+ t := it.t
+ bucket := it.bucket
+ b := it.bptr
+ i := it.i
+ checkBucket := it.checkBucket
+
+next:
+ if b == nil {
+ if bucket == it.startBucket && it.wrapped {
+ // end of iteration
+ it.key = nil
+ it.elem = nil
+ return
+ }
+ if h.growing() && it.B == h.B {
+ // Iterator was started in the middle of a grow, and the grow isn't done yet.
+ // If the bucket we're looking at hasn't been filled in yet (i.e. the old
+ // bucket hasn't been evacuated) then we need to iterate through the old
+ // bucket and only return the ones that will be migrated to this bucket.
+ oldbucket := bucket & it.h.oldbucketmask()
+ b = (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
+ if !evacuated(b) {
+ checkBucket = bucket
+ } else {
+ b = (*bmap)(add(it.buckets, bucket*uintptr(t.bucketsize)))
+ checkBucket = noCheck
+ }
+ } else {
+ b = (*bmap)(add(it.buckets, bucket*uintptr(t.bucketsize)))
+ checkBucket = noCheck
+ }
+ bucket++
+ if bucket == bucketShift(it.B) {
+ bucket = 0
+ it.wrapped = true
+ }
+ i = 0
+ }
+ for ; i < bucketCnt; i++ {
+ offi := (i + it.offset) & (bucketCnt - 1)
+ if isEmpty(b.tophash[offi]) || b.tophash[offi] == evacuatedEmpty {
+ // TODO: emptyRest is hard to use here, as we start iterating
+ // in the middle of a bucket. It's feasible, just tricky.
+ continue
+ }
+ k := add(unsafe.Pointer(b), dataOffset+uintptr(offi)*uintptr(t.keysize))
+ if t.indirectkey() {
+ k = *((*unsafe.Pointer)(k))
+ }
+ e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+uintptr(offi)*uintptr(t.elemsize))
+ if checkBucket != noCheck && !h.sameSizeGrow() {
+ // Special case: iterator was started during a grow to a larger size
+ // and the grow is not done yet. We're working on a bucket whose
+ // oldbucket has not been evacuated yet. Or at least, it wasn't
+ // evacuated when we started the bucket. So we're iterating
+ // through the oldbucket, skipping any keys that will go
+ // to the other new bucket (each oldbucket expands to two
+ // buckets during a grow).
+ if t.reflexivekey() || t.key.equal(k, k) {
+ // If the item in the oldbucket is not destined for
+ // the current new bucket in the iteration, skip it.
+ hash := t.hasher(k, uintptr(h.hash0))
+ if hash&bucketMask(it.B) != checkBucket {
+ continue
+ }
+ } else {
+ // Hash isn't repeatable if k != k (NaNs). We need a
+ // repeatable and randomish choice of which direction
+ // to send NaNs during evacuation. We'll use the low
+ // bit of tophash to decide which way NaNs go.
+ // NOTE: this case is why we need two evacuate tophash
+ // values, evacuatedX and evacuatedY, that differ in
+ // their low bit.
+ if checkBucket>>(it.B-1) != uintptr(b.tophash[offi]&1) {
+ continue
+ }
+ }
+ }
+ if (b.tophash[offi] != evacuatedX && b.tophash[offi] != evacuatedY) ||
+ !(t.reflexivekey() || t.key.equal(k, k)) {
+ // This is the golden data, we can return it.
+ // OR
+ // key!=key, so the entry can't be deleted or updated, so we can just return it.
+ // That's lucky for us because when key!=key we can't look it up successfully.
+ it.key = k
+ if t.indirectelem() {
+ e = *((*unsafe.Pointer)(e))
+ }
+ it.elem = e
+ } else {
+ // The hash table has grown since the iterator was started.
+ // The golden data for this key is now somewhere else.
+ // Check the current hash table for the data.
+ // This code handles the case where the key
+ // has been deleted, updated, or deleted and reinserted.
+ // NOTE: we need to regrab the key as it has potentially been
+ // updated to an equal() but not identical key (e.g. +0.0 vs -0.0).
+ rk, re := mapaccessK(t, h, k)
+ if rk == nil {
+ continue // key has been deleted
+ }
+ it.key = rk
+ it.elem = re
+ }
+ it.bucket = bucket
+ if it.bptr != b { // avoid unnecessary write barrier; see issue 14921
+ it.bptr = b
+ }
+ it.i = i + 1
+ it.checkBucket = checkBucket
+ return
+ }
+ b = b.overflow(t)
+ i = 0
+ goto next
+}
+
+// mapclear deletes all keys from a map.
+func mapclear(t *maptype, h *hmap) {
+ if raceenabled && h != nil {
+ callerpc := getcallerpc()
+ pc := abi.FuncPCABIInternal(mapclear)
+ racewritepc(unsafe.Pointer(h), callerpc, pc)
+ }
+
+ if h == nil || h.count == 0 {
+ return
+ }
+
+ if h.flags&hashWriting != 0 {
+ fatal("concurrent map writes")
+ }
+
+ h.flags ^= hashWriting
+
+ h.flags &^= sameSizeGrow
+ h.oldbuckets = nil
+ h.nevacuate = 0
+ h.noverflow = 0
+ h.count = 0
+
+ // Reset the hash seed to make it more difficult for attackers to
+ // repeatedly trigger hash collisions. See issue 25237.
+ h.hash0 = fastrand()
+
+ // Keep the mapextra allocation but clear any extra information.
+ if h.extra != nil {
+ *h.extra = mapextra{}
+ }
+
+ // makeBucketArray clears the memory pointed to by h.buckets
+ // and recovers any overflow buckets by generating them
+ // as if h.buckets was newly alloced.
+ _, nextOverflow := makeBucketArray(t, h.B, h.buckets)
+ if nextOverflow != nil {
+ // If overflow buckets are created then h.extra
+ // will have been allocated during initial bucket creation.
+ h.extra.nextOverflow = nextOverflow
+ }
+
+ if h.flags&hashWriting == 0 {
+ fatal("concurrent map writes")
+ }
+ h.flags &^= hashWriting
+}
+
+func hashGrow(t *maptype, h *hmap) {
+ // If we've hit the load factor, get bigger.
+ // Otherwise, there are too many overflow buckets,
+ // so keep the same number of buckets and "grow" laterally.
+ bigger := uint8(1)
+ if !overLoadFactor(h.count+1, h.B) {
+ bigger = 0
+ h.flags |= sameSizeGrow
+ }
+ oldbuckets := h.buckets
+ newbuckets, nextOverflow := makeBucketArray(t, h.B+bigger, nil)
+
+ flags := h.flags &^ (iterator | oldIterator)
+ if h.flags&iterator != 0 {
+ flags |= oldIterator
+ }
+ // commit the grow (atomic wrt gc)
+ h.B += bigger
+ h.flags = flags
+ h.oldbuckets = oldbuckets
+ h.buckets = newbuckets
+ h.nevacuate = 0
+ h.noverflow = 0
+
+ if h.extra != nil && h.extra.overflow != nil {
+ // Promote current overflow buckets to the old generation.
+ if h.extra.oldoverflow != nil {
+ throw("oldoverflow is not nil")
+ }
+ h.extra.oldoverflow = h.extra.overflow
+ h.extra.overflow = nil
+ }
+ if nextOverflow != nil {
+ if h.extra == nil {
+ h.extra = new(mapextra)
+ }
+ h.extra.nextOverflow = nextOverflow
+ }
+
+ // the actual copying of the hash table data is done incrementally
+ // by growWork() and evacuate().
+}
+
+// overLoadFactor reports whether count items placed in 1<<B buckets is over loadFactor.
+func overLoadFactor(count int, B uint8) bool {
+ return count > bucketCnt && uintptr(count) > loadFactorNum*(bucketShift(B)/loadFactorDen)
+}
+
+// tooManyOverflowBuckets reports whether noverflow buckets is too many for a map with 1<<B buckets.
+// Note that most of these overflow buckets must be in sparse use;
+// if use was dense, then we'd have already triggered regular map growth.
+func tooManyOverflowBuckets(noverflow uint16, B uint8) bool {
+ // If the threshold is too low, we do extraneous work.
+ // If the threshold is too high, maps that grow and shrink can hold on to lots of unused memory.
+ // "too many" means (approximately) as many overflow buckets as regular buckets.
+ // See incrnoverflow for more details.
+ if B > 15 {
+ B = 15
+ }
+ // The compiler doesn't see here that B < 16; mask B to generate shorter shift code.
+ return noverflow >= uint16(1)<<(B&15)
+}
+
+// growing reports whether h is growing. The growth may be to the same size or bigger.
+func (h *hmap) growing() bool {
+ return h.oldbuckets != nil
+}
+
+// sameSizeGrow reports whether the current growth is to a map of the same size.
+func (h *hmap) sameSizeGrow() bool {
+ return h.flags&sameSizeGrow != 0
+}
+
+// noldbuckets calculates the number of buckets prior to the current map growth.
+func (h *hmap) noldbuckets() uintptr {
+ oldB := h.B
+ if !h.sameSizeGrow() {
+ oldB--
+ }
+ return bucketShift(oldB)
+}
+
+// oldbucketmask provides a mask that can be applied to calculate n % noldbuckets().
+func (h *hmap) oldbucketmask() uintptr {
+ return h.noldbuckets() - 1
+}
+
+func growWork(t *maptype, h *hmap, bucket uintptr) {
+ // make sure we evacuate the oldbucket corresponding
+ // to the bucket we're about to use
+ evacuate(t, h, bucket&h.oldbucketmask())
+
+ // evacuate one more oldbucket to make progress on growing
+ if h.growing() {
+ evacuate(t, h, h.nevacuate)
+ }
+}
+
+func bucketEvacuated(t *maptype, h *hmap, bucket uintptr) bool {
+ b := (*bmap)(add(h.oldbuckets, bucket*uintptr(t.bucketsize)))
+ return evacuated(b)
+}
+
+// evacDst is an evacuation destination.
+type evacDst struct {
+ b *bmap // current destination bucket
+ i int // key/elem index into b
+ k unsafe.Pointer // pointer to current key storage
+ e unsafe.Pointer // pointer to current elem storage
+}
+
+func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
+ b := (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
+ newbit := h.noldbuckets()
+ if !evacuated(b) {
+ // TODO: reuse overflow buckets instead of using new ones, if there
+ // is no iterator using the old buckets. (If !oldIterator.)
+
+ // xy contains the x and y (low and high) evacuation destinations.
+ var xy [2]evacDst
+ x := &xy[0]
+ x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize)))
+ x.k = add(unsafe.Pointer(x.b), dataOffset)
+ x.e = add(x.k, bucketCnt*uintptr(t.keysize))
+
+ if !h.sameSizeGrow() {
+ // Only calculate y pointers if we're growing bigger.
+ // Otherwise GC can see bad pointers.
+ y := &xy[1]
+ y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize)))
+ y.k = add(unsafe.Pointer(y.b), dataOffset)
+ y.e = add(y.k, bucketCnt*uintptr(t.keysize))
+ }
+
+ for ; b != nil; b = b.overflow(t) {
+ k := add(unsafe.Pointer(b), dataOffset)
+ e := add(k, bucketCnt*uintptr(t.keysize))
+ for i := 0; i < bucketCnt; i, k, e = i+1, add(k, uintptr(t.keysize)), add(e, uintptr(t.elemsize)) {
+ top := b.tophash[i]
+ if isEmpty(top) {
+ b.tophash[i] = evacuatedEmpty
+ continue
+ }
+ if top < minTopHash {
+ throw("bad map state")
+ }
+ k2 := k
+ if t.indirectkey() {
+ k2 = *((*unsafe.Pointer)(k2))
+ }
+ var useY uint8
+ if !h.sameSizeGrow() {
+ // Compute hash to make our evacuation decision (whether we need
+ // to send this key/elem to bucket x or bucket y).
+ hash := t.hasher(k2, uintptr(h.hash0))
+ if h.flags&iterator != 0 && !t.reflexivekey() && !t.key.equal(k2, k2) {
+ // If key != key (NaNs), then the hash could be (and probably
+ // will be) entirely different from the old hash. Moreover,
+ // it isn't reproducible. Reproducibility is required in the
+ // presence of iterators, as our evacuation decision must
+ // match whatever decision the iterator made.
+ // Fortunately, we have the freedom to send these keys either
+ // way. Also, tophash is meaningless for these kinds of keys.
+ // We let the low bit of tophash drive the evacuation decision.
+ // We recompute a new random tophash for the next level so
+ // these keys will get evenly distributed across all buckets
+ // after multiple grows.
+ useY = top & 1
+ top = tophash(hash)
+ } else {
+ if hash&newbit != 0 {
+ useY = 1
+ }
+ }
+ }
+
+ if evacuatedX+1 != evacuatedY || evacuatedX^1 != evacuatedY {
+ throw("bad evacuatedN")
+ }
+
+ b.tophash[i] = evacuatedX + useY // evacuatedX + 1 == evacuatedY
+ dst := &xy[useY] // evacuation destination
+
+ if dst.i == bucketCnt {
+ dst.b = h.newoverflow(t, dst.b)
+ dst.i = 0
+ dst.k = add(unsafe.Pointer(dst.b), dataOffset)
+ dst.e = add(dst.k, bucketCnt*uintptr(t.keysize))
+ }
+ dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
+ if t.indirectkey() {
+ *(*unsafe.Pointer)(dst.k) = k2 // copy pointer
+ } else {
+ typedmemmove(t.key, dst.k, k) // copy elem
+ }
+ if t.indirectelem() {
+ *(*unsafe.Pointer)(dst.e) = *(*unsafe.Pointer)(e)
+ } else {
+ typedmemmove(t.elem, dst.e, e)
+ }
+ dst.i++
+ // These updates might push these pointers past the end of the
+ // key or elem arrays. That's ok, as we have the overflow pointer
+ // at the end of the bucket to protect against pointing past the
+ // end of the bucket.
+ dst.k = add(dst.k, uintptr(t.keysize))
+ dst.e = add(dst.e, uintptr(t.elemsize))
+ }
+ }
+ // Unlink the overflow buckets & clear key/elem to help GC.
+ if h.flags&oldIterator == 0 && t.bucket.ptrdata != 0 {
+ b := add(h.oldbuckets, oldbucket*uintptr(t.bucketsize))
+ // Preserve b.tophash because the evacuation
+ // state is maintained there.
+ ptr := add(b, dataOffset)
+ n := uintptr(t.bucketsize) - dataOffset
+ memclrHasPointers(ptr, n)
+ }
+ }
+
+ if oldbucket == h.nevacuate {
+ advanceEvacuationMark(h, t, newbit)
+ }
+}
+
+func advanceEvacuationMark(h *hmap, t *maptype, newbit uintptr) {
+ h.nevacuate++
+ // Experiments suggest that 1024 is overkill by at least an order of magnitude.
+ // Put it in there as a safeguard anyway, to ensure O(1) behavior.
+ stop := h.nevacuate + 1024
+ if stop > newbit {
+ stop = newbit
+ }
+ for h.nevacuate != stop && bucketEvacuated(t, h, h.nevacuate) {
+ h.nevacuate++
+ }
+ if h.nevacuate == newbit { // newbit == # of oldbuckets
+ // Growing is all done. Free old main bucket array.
+ h.oldbuckets = nil
+ // Can discard old overflow buckets as well.
+ // If they are still referenced by an iterator,
+ // then the iterator holds a pointers to the slice.
+ if h.extra != nil {
+ h.extra.oldoverflow = nil
+ }
+ h.flags &^= sameSizeGrow
+ }
+}
+
+// Reflect stubs. Called from ../reflect/asm_*.s
+
+//go:linkname reflect_makemap reflect.makemap
+func reflect_makemap(t *maptype, cap int) *hmap {
+ // Check invariants and reflects math.
+ if t.key.equal == nil {
+ throw("runtime.reflect_makemap: unsupported map key type")
+ }
+ if t.key.size > maxKeySize && (!t.indirectkey() || t.keysize != uint8(goarch.PtrSize)) ||
+ t.key.size <= maxKeySize && (t.indirectkey() || t.keysize != uint8(t.key.size)) {
+ throw("key size wrong")
+ }
+ if t.elem.size > maxElemSize && (!t.indirectelem() || t.elemsize != uint8(goarch.PtrSize)) ||
+ t.elem.size <= maxElemSize && (t.indirectelem() || t.elemsize != uint8(t.elem.size)) {
+ throw("elem size wrong")
+ }
+ if t.key.align > bucketCnt {
+ throw("key align too big")
+ }
+ if t.elem.align > bucketCnt {
+ throw("elem align too big")
+ }
+ if t.key.size%uintptr(t.key.align) != 0 {
+ throw("key size not a multiple of key align")
+ }
+ if t.elem.size%uintptr(t.elem.align) != 0 {
+ throw("elem size not a multiple of elem align")
+ }
+ if bucketCnt < 8 {
+ throw("bucketsize too small for proper alignment")
+ }
+ if dataOffset%uintptr(t.key.align) != 0 {
+ throw("need padding in bucket (key)")
+ }
+ if dataOffset%uintptr(t.elem.align) != 0 {
+ throw("need padding in bucket (elem)")
+ }
+
+ return makemap(t, cap, nil)
+}
+
+//go:linkname reflect_mapaccess reflect.mapaccess
+func reflect_mapaccess(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
+ elem, ok := mapaccess2(t, h, key)
+ if !ok {
+ // reflect wants nil for a missing element
+ elem = nil
+ }
+ return elem
+}
+
+//go:linkname reflect_mapaccess_faststr reflect.mapaccess_faststr
+func reflect_mapaccess_faststr(t *maptype, h *hmap, key string) unsafe.Pointer {
+ elem, ok := mapaccess2_faststr(t, h, key)
+ if !ok {
+ // reflect wants nil for a missing element
+ elem = nil
+ }
+ return elem
+}
+
+//go:linkname reflect_mapassign reflect.mapassign
+func reflect_mapassign(t *maptype, h *hmap, key unsafe.Pointer, elem unsafe.Pointer) {
+ p := mapassign(t, h, key)
+ typedmemmove(t.elem, p, elem)
+}
+
+//go:linkname reflect_mapassign_faststr reflect.mapassign_faststr
+func reflect_mapassign_faststr(t *maptype, h *hmap, key string, elem unsafe.Pointer) {
+ p := mapassign_faststr(t, h, key)
+ typedmemmove(t.elem, p, elem)
+}
+
+//go:linkname reflect_mapdelete reflect.mapdelete
+func reflect_mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
+ mapdelete(t, h, key)
+}
+
+//go:linkname reflect_mapdelete_faststr reflect.mapdelete_faststr
+func reflect_mapdelete_faststr(t *maptype, h *hmap, key string) {
+ mapdelete_faststr(t, h, key)
+}
+
+//go:linkname reflect_mapiterinit reflect.mapiterinit
+func reflect_mapiterinit(t *maptype, h *hmap, it *hiter) {
+ mapiterinit(t, h, it)
+}
+
+//go:linkname reflect_mapiternext reflect.mapiternext
+func reflect_mapiternext(it *hiter) {
+ mapiternext(it)
+}
+
+//go:linkname reflect_mapiterkey reflect.mapiterkey
+func reflect_mapiterkey(it *hiter) unsafe.Pointer {
+ return it.key
+}
+
+//go:linkname reflect_mapiterelem reflect.mapiterelem
+func reflect_mapiterelem(it *hiter) unsafe.Pointer {
+ return it.elem
+}
+
+//go:linkname reflect_maplen reflect.maplen
+func reflect_maplen(h *hmap) int {
+ if h == nil {
+ return 0
+ }
+ if raceenabled {
+ callerpc := getcallerpc()
+ racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
+ }
+ return h.count
+}
+
+//go:linkname reflectlite_maplen internal/reflectlite.maplen
+func reflectlite_maplen(h *hmap) int {
+ if h == nil {
+ return 0
+ }
+ if raceenabled {
+ callerpc := getcallerpc()
+ racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
+ }
+ return h.count
+}
+
+const maxZero = 1024 // must match value in reflect/value.go:maxZero cmd/compile/internal/gc/walk.go:zeroValSize
+var zeroVal [maxZero]byte