runtime: rename map implementation and test files to use a common prefix

Rename all map implementation and test files to use "map"
as a file name prefix instead of "hashmap" for the implementation
and "map" for the test file names.

Change-Id: I7b317c1f7a660b95c6d1f1a185866f2839e69446
Reviewed-on: https://go-review.googlesource.com/90336
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 0 insertions, 1249 deletions

diff --git a/src/runtime/hashmap.go b/src/runtime/hashmap.go
deleted file mode 100644
index eddb045622..0000000000
--- a/src/runtime/hashmap.go
+++ /dev/null
@@ -1,1249 +0,0 @@
-// 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/value 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 values)
-//  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/value 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 (
-	"runtime/internal/atomic"
-	"runtime/internal/sys"
-	"unsafe"
-)
-
-const (
-	// Maximum number of key/value 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/loadFactDen, to allow integer math.
-	loadFactorNum = 13
-	loadFactorDen = 2
-
-	// Maximum key or value size to keep inline (instead of mallocing per element).
-	// Must fit in a uint8.
-	// Fast versions cannot handle big values - the cutoff size for
-	// fast versions in ../../cmd/internal/gc/walk.go must be at most this value.
-	maxKeySize   = 128
-	maxValueSize = 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).
-	empty          = 0 // cell is empty
-	evacuatedEmpty = 1 // cell is empty, bucket is evacuated.
-	evacuatedX     = 2 // key/value 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.
-	minTopHash     = 4 // 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*sys.PtrSize) - 1
-)
-
-// A header for a Go map.
-type hmap struct {
-	// Note: the format of the Hmap is encoded in ../../cmd/internal/gc/reflect.go and
-	// ../reflect/type.go. Don't change this structure without also changing that code!
-	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 value 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.overflow and h.map.oldoverflow.
-	// overflow and oldoverflow are only used if key and value 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 values.
-	// NOTE: packing all the keys together and then all the values together makes the
-	// code a bit more complicated than alternating key/value/key/value/... 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/internal/gc/reflect.go to indicate
-// the layout of this structure.
-type hiter struct {
-	key         unsafe.Pointer // Must be in first position.  Write nil to indicate iteration end (see cmd/internal/gc/range.go).
-	value       unsafe.Pointer // Must be in second position (see cmd/internal/gc/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 {
-	if sys.GoarchAmd64|sys.GoarchAmd64p32|sys.Goarch386 != 0 {
-		b &= sys.PtrSize*8 - 1 // help x86 archs remove shift overflow checks
-	}
-	return uintptr(1) << b
-}
-
-// 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 >> (sys.PtrSize*8 - 8))
-	if top < minTopHash {
-		top += minTopHash
-	}
-	return top
-}
-
-func evacuated(b *bmap) bool {
-	h := b.tophash[0]
-	return h > empty && h < minTopHash
-}
-
-func (b *bmap) overflow(t *maptype) *bmap {
-	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.PtrSize))
-}
-
-func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
-	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-sys.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.kind&kindNoPointers != 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)
-}
-
-// makehmap_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 {
-	// The size of hmap should be 48 bytes on 64 bit
-	// and 28 bytes on 32 bit platforms.
-	if sz := unsafe.Sizeof(hmap{}); sz != 8+5*sys.PtrSize {
-		println("runtime: sizeof(hmap) =", sz, ", t.hmap.size =", t.hmap.size)
-		throw("bad hmap size")
-	}
-
-	if hint < 0 || hint > int(maxSliceCap(t.bucket.size)) {
-		hint = 0
-	}
-
-	// initialize Hmap
-	if h == nil {
-		h = new(hmap)
-	}
-	h.hash0 = fastrand()
-
-	// find size parameter which will hold the requested # of elements
-	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)
-		if nextOverflow != nil {
-			h.extra = new(mapextra)
-			h.extra.nextOverflow = nextOverflow
-		}
-	}
-
-	return h
-}
-
-// mapaccess1 returns a pointer to h[key].  Never returns nil, instead
-// it will return a reference to the zero object for the value 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 := funcPC(mapaccess1)
-		racereadpc(unsafe.Pointer(h), callerpc, pc)
-		raceReadObjectPC(t.key, key, callerpc, pc)
-	}
-	if msanenabled && h != nil {
-		msanread(key, t.key.size)
-	}
-	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0])
-	}
-	if h.flags&hashWriting != 0 {
-		throw("concurrent map read and map write")
-	}
-	alg := t.key.alg
-	hash := alg.hash(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)
-	for ; b != nil; b = b.overflow(t) {
-		for i := uintptr(0); i < bucketCnt; i++ {
-			if b.tophash[i] != top {
-				continue
-			}
-			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-			if t.indirectkey {
-				k = *((*unsafe.Pointer)(k))
-			}
-			if alg.equal(key, k) {
-				v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-				if t.indirectvalue {
-					v = *((*unsafe.Pointer)(v))
-				}
-				return v
-			}
-		}
-	}
-	return unsafe.Pointer(&zeroVal[0])
-}
-
-func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
-	if raceenabled && h != nil {
-		callerpc := getcallerpc()
-		pc := funcPC(mapaccess2)
-		racereadpc(unsafe.Pointer(h), callerpc, pc)
-		raceReadObjectPC(t.key, key, callerpc, pc)
-	}
-	if msanenabled && h != nil {
-		msanread(key, t.key.size)
-	}
-	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0]), false
-	}
-	if h.flags&hashWriting != 0 {
-		throw("concurrent map read and map write")
-	}
-	alg := t.key.alg
-	hash := alg.hash(key, uintptr(h.hash0))
-	m := bucketMask(h.B)
-	b := (*bmap)(unsafe.Pointer(uintptr(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)(unsafe.Pointer(uintptr(c) + (hash&m)*uintptr(t.bucketsize)))
-		if !evacuated(oldb) {
-			b = oldb
-		}
-	}
-	top := tophash(hash)
-	for ; b != nil; b = b.overflow(t) {
-		for i := uintptr(0); i < bucketCnt; i++ {
-			if b.tophash[i] != top {
-				continue
-			}
-			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-			if t.indirectkey {
-				k = *((*unsafe.Pointer)(k))
-			}
-			if alg.equal(key, k) {
-				v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-				if t.indirectvalue {
-					v = *((*unsafe.Pointer)(v))
-				}
-				return v, true
-			}
-		}
-	}
-	return unsafe.Pointer(&zeroVal[0]), false
-}
-
-// returns both key and value. 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
-	}
-	alg := t.key.alg
-	hash := alg.hash(key, uintptr(h.hash0))
-	m := bucketMask(h.B)
-	b := (*bmap)(unsafe.Pointer(uintptr(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)(unsafe.Pointer(uintptr(c) + (hash&m)*uintptr(t.bucketsize)))
-		if !evacuated(oldb) {
-			b = oldb
-		}
-	}
-	top := tophash(hash)
-	for ; b != nil; b = b.overflow(t) {
-		for i := uintptr(0); i < bucketCnt; i++ {
-			if b.tophash[i] != top {
-				continue
-			}
-			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-			if t.indirectkey {
-				k = *((*unsafe.Pointer)(k))
-			}
-			if alg.equal(key, k) {
-				v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-				if t.indirectvalue {
-					v = *((*unsafe.Pointer)(v))
-				}
-				return k, v
-			}
-		}
-	}
-	return nil, nil
-}
-
-func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointer {
-	v := mapaccess1(t, h, key)
-	if v == unsafe.Pointer(&zeroVal[0]) {
-		return zero
-	}
-	return v
-}
-
-func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Pointer, bool) {
-	v := mapaccess1(t, h, key)
-	if v == unsafe.Pointer(&zeroVal[0]) {
-		return zero, false
-	}
-	return v, 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 := funcPC(mapassign)
-		racewritepc(unsafe.Pointer(h), callerpc, pc)
-		raceReadObjectPC(t.key, key, callerpc, pc)
-	}
-	if msanenabled {
-		msanread(key, t.key.size)
-	}
-	if h.flags&hashWriting != 0 {
-		throw("concurrent map writes")
-	}
-	alg := t.key.alg
-	hash := alg.hash(key, uintptr(h.hash0))
-
-	// Set hashWriting after calling alg.hash, since alg.hash 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)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize)))
-	top := tophash(hash)
-
-	var inserti *uint8
-	var insertk unsafe.Pointer
-	var val unsafe.Pointer
-	for {
-		for i := uintptr(0); i < bucketCnt; i++ {
-			if b.tophash[i] != top {
-				if b.tophash[i] == empty && inserti == nil {
-					inserti = &b.tophash[i]
-					insertk = add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-					val = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-				}
-				continue
-			}
-			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-			if t.indirectkey {
-				k = *((*unsafe.Pointer)(k))
-			}
-			if !alg.equal(key, k) {
-				continue
-			}
-			// already have a mapping for key. Update it.
-			if t.needkeyupdate {
-				typedmemmove(t.key, k, key)
-			}
-			val = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-			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 {
-		// all current buckets are full, allocate a new one.
-		newb := h.newoverflow(t, b)
-		inserti = &newb.tophash[0]
-		insertk = add(unsafe.Pointer(newb), dataOffset)
-		val = add(insertk, bucketCnt*uintptr(t.keysize))
-	}
-
-	// store new key/value at insert position
-	if t.indirectkey {
-		kmem := newobject(t.key)
-		*(*unsafe.Pointer)(insertk) = kmem
-		insertk = kmem
-	}
-	if t.indirectvalue {
-		vmem := newobject(t.elem)
-		*(*unsafe.Pointer)(val) = vmem
-	}
-	typedmemmove(t.key, insertk, key)
-	*inserti = top
-	h.count++
-
-done:
-	if h.flags&hashWriting == 0 {
-		throw("concurrent map writes")
-	}
-	h.flags &^= hashWriting
-	if t.indirectvalue {
-		val = *((*unsafe.Pointer)(val))
-	}
-	return val
-}
-
-func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
-	if raceenabled && h != nil {
-		callerpc := getcallerpc()
-		pc := funcPC(mapdelete)
-		racewritepc(unsafe.Pointer(h), callerpc, pc)
-		raceReadObjectPC(t.key, key, callerpc, pc)
-	}
-	if msanenabled && h != nil {
-		msanread(key, t.key.size)
-	}
-	if h == nil || h.count == 0 {
-		return
-	}
-	if h.flags&hashWriting != 0 {
-		throw("concurrent map writes")
-	}
-
-	alg := t.key.alg
-	hash := alg.hash(key, uintptr(h.hash0))
-
-	// Set hashWriting after calling alg.hash, since alg.hash 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)))
-	top := tophash(hash)
-search:
-	for ; b != nil; b = b.overflow(t) {
-		for i := uintptr(0); i < bucketCnt; i++ {
-			if b.tophash[i] != top {
-				continue
-			}
-			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
-			k2 := k
-			if t.indirectkey {
-				k2 = *((*unsafe.Pointer)(k2))
-			}
-			if !alg.equal(key, k2) {
-				continue
-			}
-			// Only clear key if there are pointers in it.
-			if t.indirectkey {
-				*(*unsafe.Pointer)(k) = nil
-			} else if t.key.kind&kindNoPointers == 0 {
-				memclrHasPointers(k, t.key.size)
-			}
-			// Only clear value if there are pointers in it.
-			if t.indirectvalue || t.elem.kind&kindNoPointers == 0 {
-				v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
-				if t.indirectvalue {
-					*(*unsafe.Pointer)(v) = nil
-				} else {
-					memclrHasPointers(v, t.elem.size)
-				}
-			}
-			b.tophash[i] = empty
-			h.count--
-			break search
-		}
-	}
-
-	if h.flags&hashWriting == 0 {
-		throw("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, funcPC(mapiterinit))
-	}
-
-	if h == nil || h.count == 0 {
-		return
-	}
-
-	if unsafe.Sizeof(hiter{})/sys.PtrSize != 12 {
-		throw("hash_iter size incorrect") // see ../../cmd/internal/gc/reflect.go
-	}
-	it.t = t
-	it.h = h
-
-	// grab snapshot of bucket state
-	it.B = h.B
-	it.buckets = h.buckets
-	if t.bucket.kind&kindNoPointers != 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
-	r := uintptr(fastrand())
-	if h.B > 31-bucketCntBits {
-		r += uintptr(fastrand()) << 31
-	}
-	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, funcPC(mapiternext))
-	}
-	if h.flags&hashWriting != 0 {
-		throw("concurrent map iteration and map write")
-	}
-	t := it.t
-	bucket := it.bucket
-	b := it.bptr
-	i := it.i
-	checkBucket := it.checkBucket
-	alg := t.key.alg
-
-next:
-	if b == nil {
-		if bucket == it.startBucket && it.wrapped {
-			// end of iteration
-			it.key = nil
-			it.value = 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 b.tophash[offi] == empty || b.tophash[offi] == evacuatedEmpty {
-			continue
-		}
-		k := add(unsafe.Pointer(b), dataOffset+uintptr(offi)*uintptr(t.keysize))
-		if t.indirectkey {
-			k = *((*unsafe.Pointer)(k))
-		}
-		v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+uintptr(offi)*uintptr(t.valuesize))
-		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 || alg.equal(k, k) {
-				// If the item in the oldbucket is not destined for
-				// the current new bucket in the iteration, skip it.
-				hash := alg.hash(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 || alg.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.indirectvalue {
-				v = *((*unsafe.Pointer)(v))
-			}
-			it.value = v
-		} 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, rv := mapaccessK(t, h, k)
-			if rk == nil {
-				continue // key has been deleted
-			}
-			it.key = rk
-			it.value = rv
-		}
-		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
-}
-
-func makeBucketArray(t *maptype, b uint8) (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
-		}
-	}
-	buckets = newarray(t.bucket, int(nbuckets))
-	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
-}
-
-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)
-
-	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/val index into b
-	k unsafe.Pointer // pointer to current key storage
-	v unsafe.Pointer // pointer to current value 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.v = 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.v = add(y.k, bucketCnt*uintptr(t.keysize))
-		}
-
-		for ; b != nil; b = b.overflow(t) {
-			k := add(unsafe.Pointer(b), dataOffset)
-			v := add(k, bucketCnt*uintptr(t.keysize))
-			for i := 0; i < bucketCnt; i, k, v = i+1, add(k, uintptr(t.keysize)), add(v, uintptr(t.valuesize)) {
-				top := b.tophash[i]
-				if top == empty {
-					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/value to bucket x or bucket y).
-					hash := t.key.alg.hash(k2, uintptr(h.hash0))
-					if h.flags&iterator != 0 && !t.reflexivekey && !t.key.alg.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 {
-					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.v = 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 value
-				}
-				if t.indirectvalue {
-					*(*unsafe.Pointer)(dst.v) = *(*unsafe.Pointer)(v)
-				} else {
-					typedmemmove(t.elem, dst.v, v)
-				}
-				dst.i++
-				// These updates might push these pointers past the end of the
-				// key or value 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.v = add(dst.v, uintptr(t.valuesize))
-			}
-		}
-		// Unlink the overflow buckets & clear key/value to help GC.
-		if h.flags&oldIterator == 0 && t.bucket.kind&kindNoPointers == 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
-	}
-}
-
-func ismapkey(t *_type) bool {
-	return t.alg.hash != nil
-}
-
-// 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 sz := unsafe.Sizeof(hmap{}); sz != t.hmap.size {
-		println("runtime: sizeof(hmap) =", sz, ", t.hmap.size =", t.hmap.size)
-		throw("bad hmap size")
-	}
-	if !ismapkey(t.key) {
-		throw("runtime.reflect_makemap: unsupported map key type")
-	}
-	if t.key.size > maxKeySize && (!t.indirectkey || t.keysize != uint8(sys.PtrSize)) ||
-		t.key.size <= maxKeySize && (t.indirectkey || t.keysize != uint8(t.key.size)) {
-		throw("key size wrong")
-	}
-	if t.elem.size > maxValueSize && (!t.indirectvalue || t.valuesize != uint8(sys.PtrSize)) ||
-		t.elem.size <= maxValueSize && (t.indirectvalue || t.valuesize != uint8(t.elem.size)) {
-		throw("value size wrong")
-	}
-	if t.key.align > bucketCnt {
-		throw("key align too big")
-	}
-	if t.elem.align > bucketCnt {
-		throw("value 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("value size not a multiple of value 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 (value)")
-	}
-
-	return makemap(t, cap, nil)
-}
-
-//go:linkname reflect_mapaccess reflect.mapaccess
-func reflect_mapaccess(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
-	val, ok := mapaccess2(t, h, key)
-	if !ok {
-		// reflect wants nil for a missing element
-		val = nil
-	}
-	return val
-}
-
-//go:linkname reflect_mapassign reflect.mapassign
-func reflect_mapassign(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
-	p := mapassign(t, h, key)
-	typedmemmove(t.elem, p, val)
-}
-
-//go:linkname reflect_mapdelete reflect.mapdelete
-func reflect_mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
-	mapdelete(t, h, key)
-}
-
-//go:linkname reflect_mapiterinit reflect.mapiterinit
-func reflect_mapiterinit(t *maptype, h *hmap) *hiter {
-	it := new(hiter)
-	mapiterinit(t, h, it)
-	return 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_maplen reflect.maplen
-func reflect_maplen(h *hmap) int {
-	if h == nil {
-		return 0
-	}
-	if raceenabled {
-		callerpc := getcallerpc()
-		racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
-	}
-	return h.count
-}
-
-//go:linkname reflect_ismapkey reflect.ismapkey
-func reflect_ismapkey(t *_type) bool {
-	return ismapkey(t)
-}
-
-const maxZero = 1024 // must match value in ../cmd/compile/internal/gc/walk.go
-var zeroVal [maxZero]byte