github.com/goplus/llgo@v0.8.3/internal/runtime/map.go (about)

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  // This file contains the implementation of Go's map type.
     8  //
     9  // A map is just a hash table. The data is arranged
    10  // into an array of buckets. Each bucket contains up to
    11  // 8 key/elem pairs. The low-order bits of the hash are
    12  // used to select a bucket. Each bucket contains a few
    13  // high-order bits of each hash to distinguish the entries
    14  // within a single bucket.
    15  //
    16  // If more than 8 keys hash to a bucket, we chain on
    17  // extra buckets.
    18  //
    19  // When the hashtable grows, we allocate a new array
    20  // of buckets twice as big. Buckets are incrementally
    21  // copied from the old bucket array to the new bucket array.
    22  //
    23  // Map iterators walk through the array of buckets and
    24  // return the keys in walk order (bucket #, then overflow
    25  // chain order, then bucket index).  To maintain iteration
    26  // semantics, we never move keys within their bucket (if
    27  // we did, keys might be returned 0 or 2 times).  When
    28  // growing the table, iterators remain iterating through the
    29  // old table and must check the new table if the bucket
    30  // they are iterating through has been moved ("evacuated")
    31  // to the new table.
    32  
    33  // Picking loadFactor: too large and we have lots of overflow
    34  // buckets, too small and we waste a lot of space. I wrote
    35  // a simple program to check some stats for different loads:
    36  // (64-bit, 8 byte keys and elems)
    37  //  loadFactor    %overflow  bytes/entry     hitprobe    missprobe
    38  //        4.00         2.13        20.77         3.00         4.00
    39  //        4.50         4.05        17.30         3.25         4.50
    40  //        5.00         6.85        14.77         3.50         5.00
    41  //        5.50        10.55        12.94         3.75         5.50
    42  //        6.00        15.27        11.67         4.00         6.00
    43  //        6.50        20.90        10.79         4.25         6.50
    44  //        7.00        27.14        10.15         4.50         7.00
    45  //        7.50        34.03         9.73         4.75         7.50
    46  //        8.00        41.10         9.40         5.00         8.00
    47  //
    48  // %overflow   = percentage of buckets which have an overflow bucket
    49  // bytes/entry = overhead bytes used per key/elem pair
    50  // hitprobe    = # of entries to check when looking up a present key
    51  // missprobe   = # of entries to check when looking up an absent key
    52  //
    53  // Keep in mind this data is for maximally loaded tables, i.e. just
    54  // before the table grows. Typical tables will be somewhat less loaded.
    55  
    56  import (
    57  	"unsafe"
    58  
    59  	"github.com/goplus/llgo/internal/abi"
    60  )
    61  
    62  const (
    63  	// Maximum number of key/elem pairs a bucket can hold.
    64  	bucketCntBits = abi.MapBucketCountBits
    65  	bucketCnt     = abi.MapBucketCount
    66  
    67  	// Maximum average load of a bucket that triggers growth is bucketCnt*13/16 (about 80% full)
    68  	// Because of minimum alignment rules, bucketCnt is known to be at least 8.
    69  	// Represent as loadFactorNum/loadFactorDen, to allow integer math.
    70  	loadFactorDen = 2
    71  	loadFactorNum = (bucketCnt * 13 / 16) * loadFactorDen
    72  
    73  	// Maximum key or elem size to keep inline (instead of mallocing per element).
    74  	// Must fit in a uint8.
    75  	// Fast versions cannot handle big elems - the cutoff size for
    76  	// fast versions in cmd/compile/internal/gc/walk.go must be at most this elem.
    77  	maxKeySize  = abi.MapMaxKeyBytes
    78  	maxElemSize = abi.MapMaxElemBytes
    79  
    80  	// data offset should be the size of the bmap struct, but needs to be
    81  	// aligned correctly. For amd64p32 this means 64-bit alignment
    82  	// even though pointers are 32 bit.
    83  	dataOffset = unsafe.Offsetof(struct {
    84  		b bmap
    85  		v int64
    86  	}{}.v)
    87  
    88  	// Possible tophash values. We reserve a few possibilities for special marks.
    89  	// Each bucket (including its overflow buckets, if any) will have either all or none of its
    90  	// entries in the evacuated* states (except during the evacuate() method, which only happens
    91  	// during map writes and thus no one else can observe the map during that time).
    92  	emptyRest      = 0 // this cell is empty, and there are no more non-empty cells at higher indexes or overflows.
    93  	emptyOne       = 1 // this cell is empty
    94  	evacuatedX     = 2 // key/elem is valid.  Entry has been evacuated to first half of larger table.
    95  	evacuatedY     = 3 // same as above, but evacuated to second half of larger table.
    96  	evacuatedEmpty = 4 // cell is empty, bucket is evacuated.
    97  	minTopHash     = 5 // minimum tophash for a normal filled cell.
    98  
    99  	// flags
   100  	iterator     = 1 // there may be an iterator using buckets
   101  	oldIterator  = 2 // there may be an iterator using oldbuckets
   102  	hashWriting  = 4 // a goroutine is writing to the map
   103  	sameSizeGrow = 8 // the current map growth is to a new map of the same size
   104  
   105  	// sentinel bucket ID for iterator checks
   106  	// noCheck = 1<<(8*goarch.PtrSize) - 1
   107  )
   108  
   109  // isEmpty reports whether the given tophash array entry represents an empty bucket entry.
   110  func isEmpty(x uint8) bool {
   111  	return x <= emptyOne
   112  }
   113  
   114  // A header for a Go map.
   115  type hmap struct {
   116  	// Note: the format of the hmap is also encoded in cmd/compile/internal/reflectdata/reflect.go.
   117  	// Make sure this stays in sync with the compiler's definition.
   118  	count     int // # live cells == size of map.  Must be first (used by len() builtin)
   119  	flags     uint8
   120  	B         uint8  // log_2 of # of buckets (can hold up to loadFactor * 2^B items)
   121  	noverflow uint16 // approximate number of overflow buckets; see incrnoverflow for details
   122  	hash0     uint32 // hash seed
   123  
   124  	buckets    unsafe.Pointer // array of 2^B Buckets. may be nil if count==0.
   125  	oldbuckets unsafe.Pointer // previous bucket array of half the size, non-nil only when growing
   126  	nevacuate  uintptr        // progress counter for evacuation (buckets less than this have been evacuated)
   127  
   128  	extra *mapextra // optional fields
   129  }
   130  
   131  // mapextra holds fields that are not present on all maps.
   132  type mapextra struct {
   133  	// If both key and elem do not contain pointers and are inline, then we mark bucket
   134  	// type as containing no pointers. This avoids scanning such maps.
   135  	// However, bmap.overflow is a pointer. In order to keep overflow buckets
   136  	// alive, we store pointers to all overflow buckets in hmap.extra.overflow and hmap.extra.oldoverflow.
   137  	// overflow and oldoverflow are only used if key and elem do not contain pointers.
   138  	// overflow contains overflow buckets for hmap.buckets.
   139  	// oldoverflow contains overflow buckets for hmap.oldbuckets.
   140  	// The indirection allows to store a pointer to the slice in hiter.
   141  	overflow    *[]*bmap
   142  	oldoverflow *[]*bmap
   143  
   144  	// nextOverflow holds a pointer to a free overflow bucket.
   145  	nextOverflow *bmap
   146  }
   147  
   148  // A bucket for a Go map.
   149  type bmap struct {
   150  	// tophash generally contains the top byte of the hash value
   151  	// for each key in this bucket. If tophash[0] < minTopHash,
   152  	// tophash[0] is a bucket evacuation state instead.
   153  	tophash [bucketCnt]uint8
   154  	// Followed by bucketCnt keys and then bucketCnt elems.
   155  	// NOTE: packing all the keys together and then all the elems together makes the
   156  	// code a bit more complicated than alternating key/elem/key/elem/... but it allows
   157  	// us to eliminate padding which would be needed for, e.g., map[int64]int8.
   158  	// Followed by an overflow pointer.
   159  }
   160  
   161  /*
   162  // A hash iteration structure.
   163  // If you modify hiter, also change cmd/compile/internal/reflectdata/reflect.go
   164  // and reflect/value.go to match the layout of this structure.
   165  type hiter struct {
   166  	key         unsafe.Pointer // Must be in first position.  Write nil to indicate iteration end (see cmd/compile/internal/walk/range.go).
   167  	elem        unsafe.Pointer // Must be in second position (see cmd/compile/internal/walk/range.go).
   168  	t           *maptype
   169  	h           *hmap
   170  	buckets     unsafe.Pointer // bucket ptr at hash_iter initialization time
   171  	bptr        *bmap          // current bucket
   172  	overflow    *[]*bmap       // keeps overflow buckets of hmap.buckets alive
   173  	oldoverflow *[]*bmap       // keeps overflow buckets of hmap.oldbuckets alive
   174  	startBucket uintptr        // bucket iteration started at
   175  	offset      uint8          // intra-bucket offset to start from during iteration (should be big enough to hold bucketCnt-1)
   176  	wrapped     bool           // already wrapped around from end of bucket array to beginning
   177  	B           uint8
   178  	i           uint8
   179  	bucket      uintptr
   180  	checkBucket uintptr
   181  }
   182  
   183  // bucketShift returns 1<<b, optimized for code generation.
   184  func bucketShift(b uint8) uintptr {
   185  	// Masking the shift amount allows overflow checks to be elided.
   186  	return uintptr(1) << (b & (goarch.PtrSize*8 - 1))
   187  }
   188  
   189  // bucketMask returns 1<<b - 1, optimized for code generation.
   190  func bucketMask(b uint8) uintptr {
   191  	return bucketShift(b) - 1
   192  }
   193  
   194  // tophash calculates the tophash value for hash.
   195  func tophash(hash uintptr) uint8 {
   196  	top := uint8(hash >> (goarch.PtrSize*8 - 8))
   197  	if top < minTopHash {
   198  		top += minTopHash
   199  	}
   200  	return top
   201  }
   202  
   203  func evacuated(b *bmap) bool {
   204  	h := b.tophash[0]
   205  	return h > emptyOne && h < minTopHash
   206  }
   207  
   208  func (b *bmap) overflow(t *maptype) *bmap {
   209  	return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.BucketSize)-goarch.PtrSize))
   210  }
   211  
   212  func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
   213  	*(**bmap)(add(unsafe.Pointer(b), uintptr(t.BucketSize)-goarch.PtrSize)) = ovf
   214  }
   215  
   216  func (b *bmap) keys() unsafe.Pointer {
   217  	return add(unsafe.Pointer(b), dataOffset)
   218  }
   219  
   220  // incrnoverflow increments h.noverflow.
   221  // noverflow counts the number of overflow buckets.
   222  // This is used to trigger same-size map growth.
   223  // See also tooManyOverflowBuckets.
   224  // To keep hmap small, noverflow is a uint16.
   225  // When there are few buckets, noverflow is an exact count.
   226  // When there are many buckets, noverflow is an approximate count.
   227  func (h *hmap) incrnoverflow() {
   228  	// We trigger same-size map growth if there are
   229  	// as many overflow buckets as buckets.
   230  	// We need to be able to count to 1<<h.B.
   231  	if h.B < 16 {
   232  		h.noverflow++
   233  		return
   234  	}
   235  	// Increment with probability 1/(1<<(h.B-15)).
   236  	// When we reach 1<<15 - 1, we will have approximately
   237  	// as many overflow buckets as buckets.
   238  	mask := uint32(1)<<(h.B-15) - 1
   239  	// Example: if h.B == 18, then mask == 7,
   240  	// and fastrand & 7 == 0 with probability 1/8.
   241  	if fastrand()&mask == 0 {
   242  		h.noverflow++
   243  	}
   244  }
   245  
   246  func (h *hmap) newoverflow(t *maptype, b *bmap) *bmap {
   247  	var ovf *bmap
   248  	if h.extra != nil && h.extra.nextOverflow != nil {
   249  		// We have preallocated overflow buckets available.
   250  		// See makeBucketArray for more details.
   251  		ovf = h.extra.nextOverflow
   252  		if ovf.overflow(t) == nil {
   253  			// We're not at the end of the preallocated overflow buckets. Bump the pointer.
   254  			h.extra.nextOverflow = (*bmap)(add(unsafe.Pointer(ovf), uintptr(t.BucketSize)))
   255  		} else {
   256  			// This is the last preallocated overflow bucket.
   257  			// Reset the overflow pointer on this bucket,
   258  			// which was set to a non-nil sentinel value.
   259  			ovf.setoverflow(t, nil)
   260  			h.extra.nextOverflow = nil
   261  		}
   262  	} else {
   263  		ovf = (*bmap)(newobject(t.Bucket))
   264  	}
   265  	h.incrnoverflow()
   266  	if t.Bucket.PtrBytes == 0 {
   267  		h.createOverflow()
   268  		*h.extra.overflow = append(*h.extra.overflow, ovf)
   269  	}
   270  	b.setoverflow(t, ovf)
   271  	return ovf
   272  }
   273  
   274  func (h *hmap) createOverflow() {
   275  	if h.extra == nil {
   276  		h.extra = new(mapextra)
   277  	}
   278  	if h.extra.overflow == nil {
   279  		h.extra.overflow = new([]*bmap)
   280  	}
   281  }
   282  
   283  func makemap64(t *maptype, hint int64, h *hmap) *hmap {
   284  	if int64(int(hint)) != hint {
   285  		hint = 0
   286  	}
   287  	return makemap(t, int(hint), h)
   288  }
   289  */
   290  
   291  // makemap_small implements Go map creation for make(map[k]v) and
   292  // make(map[k]v, hint) when hint is known to be at most bucketCnt
   293  // at compile time and the map needs to be allocated on the heap.
   294  func makemap_small() *hmap {
   295  	h := new(hmap)
   296  	h.hash0 = fastrand()
   297  	return h
   298  }
   299  
   300  /*
   301  // makemap implements Go map creation for make(map[k]v, hint).
   302  // If the compiler has determined that the map or the first bucket
   303  // can be created on the stack, h and/or bucket may be non-nil.
   304  // If h != nil, the map can be created directly in h.
   305  // If h.buckets != nil, bucket pointed to can be used as the first bucket.
   306  func makemap(t *maptype, hint int, h *hmap) *hmap {
   307  	mem, overflow := math.MulUintptr(uintptr(hint), t.Bucket.Size_)
   308  	if overflow || mem > maxAlloc {
   309  		hint = 0
   310  	}
   311  
   312  	// initialize Hmap
   313  	if h == nil {
   314  		h = new(hmap)
   315  	}
   316  	h.hash0 = fastrand()
   317  
   318  	// Find the size parameter B which will hold the requested # of elements.
   319  	// For hint < 0 overLoadFactor returns false since hint < bucketCnt.
   320  	B := uint8(0)
   321  	for overLoadFactor(hint, B) {
   322  		B++
   323  	}
   324  	h.B = B
   325  
   326  	// allocate initial hash table
   327  	// if B == 0, the buckets field is allocated lazily later (in mapassign)
   328  	// If hint is large zeroing this memory could take a while.
   329  	if h.B != 0 {
   330  		var nextOverflow *bmap
   331  		h.buckets, nextOverflow = makeBucketArray(t, h.B, nil)
   332  		if nextOverflow != nil {
   333  			h.extra = new(mapextra)
   334  			h.extra.nextOverflow = nextOverflow
   335  		}
   336  	}
   337  
   338  	return h
   339  }
   340  
   341  // makeBucketArray initializes a backing array for map buckets.
   342  // 1<<b is the minimum number of buckets to allocate.
   343  // dirtyalloc should either be nil or a bucket array previously
   344  // allocated by makeBucketArray with the same t and b parameters.
   345  // If dirtyalloc is nil a new backing array will be alloced and
   346  // otherwise dirtyalloc will be cleared and reused as backing array.
   347  func makeBucketArray(t *maptype, b uint8, dirtyalloc unsafe.Pointer) (buckets unsafe.Pointer, nextOverflow *bmap) {
   348  	base := bucketShift(b)
   349  	nbuckets := base
   350  	// For small b, overflow buckets are unlikely.
   351  	// Avoid the overhead of the calculation.
   352  	if b >= 4 {
   353  		// Add on the estimated number of overflow buckets
   354  		// required to insert the median number of elements
   355  		// used with this value of b.
   356  		nbuckets += bucketShift(b - 4)
   357  		sz := t.Bucket.Size_ * nbuckets
   358  		up := roundupsize(sz)
   359  		if up != sz {
   360  			nbuckets = up / t.Bucket.Size_
   361  		}
   362  	}
   363  
   364  	if dirtyalloc == nil {
   365  		buckets = newarray(t.Bucket, int(nbuckets))
   366  	} else {
   367  		// dirtyalloc was previously generated by
   368  		// the above newarray(t.Bucket, int(nbuckets))
   369  		// but may not be empty.
   370  		buckets = dirtyalloc
   371  		size := t.Bucket.Size_ * nbuckets
   372  		if t.Bucket.PtrBytes != 0 {
   373  			memclrHasPointers(buckets, size)
   374  		} else {
   375  			memclrNoHeapPointers(buckets, size)
   376  		}
   377  	}
   378  
   379  	if base != nbuckets {
   380  		// We preallocated some overflow buckets.
   381  		// To keep the overhead of tracking these overflow buckets to a minimum,
   382  		// we use the convention that if a preallocated overflow bucket's overflow
   383  		// pointer is nil, then there are more available by bumping the pointer.
   384  		// We need a safe non-nil pointer for the last overflow bucket; just use buckets.
   385  		nextOverflow = (*bmap)(add(buckets, base*uintptr(t.BucketSize)))
   386  		last := (*bmap)(add(buckets, (nbuckets-1)*uintptr(t.BucketSize)))
   387  		last.setoverflow(t, (*bmap)(buckets))
   388  	}
   389  	return buckets, nextOverflow
   390  }
   391  
   392  // mapaccess1 returns a pointer to h[key].  Never returns nil, instead
   393  // it will return a reference to the zero object for the elem type if
   394  // the key is not in the map.
   395  // NOTE: The returned pointer may keep the whole map live, so don't
   396  // hold onto it for very long.
   397  func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
   398  	if raceenabled && h != nil {
   399  		callerpc := getcallerpc()
   400  		pc := abi.FuncPCABIInternal(mapaccess1)
   401  		racereadpc(unsafe.Pointer(h), callerpc, pc)
   402  		raceReadObjectPC(t.Key, key, callerpc, pc)
   403  	}
   404  	if msanenabled && h != nil {
   405  		msanread(key, t.Key.Size_)
   406  	}
   407  	if asanenabled && h != nil {
   408  		asanread(key, t.Key.Size_)
   409  	}
   410  	if h == nil || h.count == 0 {
   411  		if t.HashMightPanic() {
   412  			t.Hasher(key, 0) // see issue 23734
   413  		}
   414  		return unsafe.Pointer(&zeroVal[0])
   415  	}
   416  	if h.flags&hashWriting != 0 {
   417  		fatal("concurrent map read and map write")
   418  	}
   419  	hash := t.Hasher(key, uintptr(h.hash0))
   420  	m := bucketMask(h.B)
   421  	b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.BucketSize)))
   422  	if c := h.oldbuckets; c != nil {
   423  		if !h.sameSizeGrow() {
   424  			// There used to be half as many buckets; mask down one more power of two.
   425  			m >>= 1
   426  		}
   427  		oldb := (*bmap)(add(c, (hash&m)*uintptr(t.BucketSize)))
   428  		if !evacuated(oldb) {
   429  			b = oldb
   430  		}
   431  	}
   432  	top := tophash(hash)
   433  bucketloop:
   434  	for ; b != nil; b = b.overflow(t) {
   435  		for i := uintptr(0); i < bucketCnt; i++ {
   436  			if b.tophash[i] != top {
   437  				if b.tophash[i] == emptyRest {
   438  					break bucketloop
   439  				}
   440  				continue
   441  			}
   442  			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   443  			if t.IndirectKey() {
   444  				k = *((*unsafe.Pointer)(k))
   445  			}
   446  			if t.Key.Equal(key, k) {
   447  				e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   448  				if t.IndirectElem() {
   449  					e = *((*unsafe.Pointer)(e))
   450  				}
   451  				return e
   452  			}
   453  		}
   454  	}
   455  	return unsafe.Pointer(&zeroVal[0])
   456  }
   457  
   458  func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
   459  	if raceenabled && h != nil {
   460  		callerpc := getcallerpc()
   461  		pc := abi.FuncPCABIInternal(mapaccess2)
   462  		racereadpc(unsafe.Pointer(h), callerpc, pc)
   463  		raceReadObjectPC(t.Key, key, callerpc, pc)
   464  	}
   465  	if msanenabled && h != nil {
   466  		msanread(key, t.Key.Size_)
   467  	}
   468  	if asanenabled && h != nil {
   469  		asanread(key, t.Key.Size_)
   470  	}
   471  	if h == nil || h.count == 0 {
   472  		if t.HashMightPanic() {
   473  			t.Hasher(key, 0) // see issue 23734
   474  		}
   475  		return unsafe.Pointer(&zeroVal[0]), false
   476  	}
   477  	if h.flags&hashWriting != 0 {
   478  		fatal("concurrent map read and map write")
   479  	}
   480  	hash := t.Hasher(key, uintptr(h.hash0))
   481  	m := bucketMask(h.B)
   482  	b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.BucketSize)))
   483  	if c := h.oldbuckets; c != nil {
   484  		if !h.sameSizeGrow() {
   485  			// There used to be half as many buckets; mask down one more power of two.
   486  			m >>= 1
   487  		}
   488  		oldb := (*bmap)(add(c, (hash&m)*uintptr(t.BucketSize)))
   489  		if !evacuated(oldb) {
   490  			b = oldb
   491  		}
   492  	}
   493  	top := tophash(hash)
   494  bucketloop:
   495  	for ; b != nil; b = b.overflow(t) {
   496  		for i := uintptr(0); i < bucketCnt; i++ {
   497  			if b.tophash[i] != top {
   498  				if b.tophash[i] == emptyRest {
   499  					break bucketloop
   500  				}
   501  				continue
   502  			}
   503  			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   504  			if t.IndirectKey() {
   505  				k = *((*unsafe.Pointer)(k))
   506  			}
   507  			if t.Key.Equal(key, k) {
   508  				e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   509  				if t.IndirectElem() {
   510  					e = *((*unsafe.Pointer)(e))
   511  				}
   512  				return e, true
   513  			}
   514  		}
   515  	}
   516  	return unsafe.Pointer(&zeroVal[0]), false
   517  }
   518  
   519  // returns both key and elem. Used by map iterator.
   520  func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer) {
   521  	if h == nil || h.count == 0 {
   522  		return nil, nil
   523  	}
   524  	hash := t.Hasher(key, uintptr(h.hash0))
   525  	m := bucketMask(h.B)
   526  	b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.BucketSize)))
   527  	if c := h.oldbuckets; c != nil {
   528  		if !h.sameSizeGrow() {
   529  			// There used to be half as many buckets; mask down one more power of two.
   530  			m >>= 1
   531  		}
   532  		oldb := (*bmap)(add(c, (hash&m)*uintptr(t.BucketSize)))
   533  		if !evacuated(oldb) {
   534  			b = oldb
   535  		}
   536  	}
   537  	top := tophash(hash)
   538  bucketloop:
   539  	for ; b != nil; b = b.overflow(t) {
   540  		for i := uintptr(0); i < bucketCnt; i++ {
   541  			if b.tophash[i] != top {
   542  				if b.tophash[i] == emptyRest {
   543  					break bucketloop
   544  				}
   545  				continue
   546  			}
   547  			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   548  			if t.IndirectKey() {
   549  				k = *((*unsafe.Pointer)(k))
   550  			}
   551  			if t.Key.Equal(key, k) {
   552  				e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   553  				if t.IndirectElem() {
   554  					e = *((*unsafe.Pointer)(e))
   555  				}
   556  				return k, e
   557  			}
   558  		}
   559  	}
   560  	return nil, nil
   561  }
   562  
   563  func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointer {
   564  	e := mapaccess1(t, h, key)
   565  	if e == unsafe.Pointer(&zeroVal[0]) {
   566  		return zero
   567  	}
   568  	return e
   569  }
   570  
   571  func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Pointer, bool) {
   572  	e := mapaccess1(t, h, key)
   573  	if e == unsafe.Pointer(&zeroVal[0]) {
   574  		return zero, false
   575  	}
   576  	return e, true
   577  }
   578  
   579  // Like mapaccess, but allocates a slot for the key if it is not present in the map.
   580  func mapassign(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
   581  	if h == nil {
   582  		panic(plainError("assignment to entry in nil map"))
   583  	}
   584  	if raceenabled {
   585  		callerpc := getcallerpc()
   586  		pc := abi.FuncPCABIInternal(mapassign)
   587  		racewritepc(unsafe.Pointer(h), callerpc, pc)
   588  		raceReadObjectPC(t.Key, key, callerpc, pc)
   589  	}
   590  	if msanenabled {
   591  		msanread(key, t.Key.Size_)
   592  	}
   593  	if asanenabled {
   594  		asanread(key, t.Key.Size_)
   595  	}
   596  	if h.flags&hashWriting != 0 {
   597  		fatal("concurrent map writes")
   598  	}
   599  	hash := t.Hasher(key, uintptr(h.hash0))
   600  
   601  	// Set hashWriting after calling t.hasher, since t.hasher may panic,
   602  	// in which case we have not actually done a write.
   603  	h.flags ^= hashWriting
   604  
   605  	if h.buckets == nil {
   606  		h.buckets = newobject(t.Bucket) // newarray(t.Bucket, 1)
   607  	}
   608  
   609  again:
   610  	bucket := hash & bucketMask(h.B)
   611  	if h.growing() {
   612  		growWork(t, h, bucket)
   613  	}
   614  	b := (*bmap)(add(h.buckets, bucket*uintptr(t.BucketSize)))
   615  	top := tophash(hash)
   616  
   617  	var inserti *uint8
   618  	var insertk unsafe.Pointer
   619  	var elem unsafe.Pointer
   620  bucketloop:
   621  	for {
   622  		for i := uintptr(0); i < bucketCnt; i++ {
   623  			if b.tophash[i] != top {
   624  				if isEmpty(b.tophash[i]) && inserti == nil {
   625  					inserti = &b.tophash[i]
   626  					insertk = add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   627  					elem = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   628  				}
   629  				if b.tophash[i] == emptyRest {
   630  					break bucketloop
   631  				}
   632  				continue
   633  			}
   634  			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   635  			if t.IndirectKey() {
   636  				k = *((*unsafe.Pointer)(k))
   637  			}
   638  			if !t.Key.Equal(key, k) {
   639  				continue
   640  			}
   641  			// already have a mapping for key. Update it.
   642  			if t.NeedKeyUpdate() {
   643  				typedmemmove(t.Key, k, key)
   644  			}
   645  			elem = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   646  			goto done
   647  		}
   648  		ovf := b.overflow(t)
   649  		if ovf == nil {
   650  			break
   651  		}
   652  		b = ovf
   653  	}
   654  
   655  	// Did not find mapping for key. Allocate new cell & add entry.
   656  
   657  	// If we hit the max load factor or we have too many overflow buckets,
   658  	// and we're not already in the middle of growing, start growing.
   659  	if !h.growing() && (overLoadFactor(h.count+1, h.B) || tooManyOverflowBuckets(h.noverflow, h.B)) {
   660  		hashGrow(t, h)
   661  		goto again // Growing the table invalidates everything, so try again
   662  	}
   663  
   664  	if inserti == nil {
   665  		// The current bucket and all the overflow buckets connected to it are full, allocate a new one.
   666  		newb := h.newoverflow(t, b)
   667  		inserti = &newb.tophash[0]
   668  		insertk = add(unsafe.Pointer(newb), dataOffset)
   669  		elem = add(insertk, bucketCnt*uintptr(t.KeySize))
   670  	}
   671  
   672  	// store new key/elem at insert position
   673  	if t.IndirectKey() {
   674  		kmem := newobject(t.Key)
   675  		*(*unsafe.Pointer)(insertk) = kmem
   676  		insertk = kmem
   677  	}
   678  	if t.IndirectElem() {
   679  		vmem := newobject(t.Elem)
   680  		*(*unsafe.Pointer)(elem) = vmem
   681  	}
   682  	typedmemmove(t.Key, insertk, key)
   683  	*inserti = top
   684  	h.count++
   685  
   686  done:
   687  	if h.flags&hashWriting == 0 {
   688  		fatal("concurrent map writes")
   689  	}
   690  	h.flags &^= hashWriting
   691  	if t.IndirectElem() {
   692  		elem = *((*unsafe.Pointer)(elem))
   693  	}
   694  	return elem
   695  }
   696  
   697  func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
   698  	if raceenabled && h != nil {
   699  		callerpc := getcallerpc()
   700  		pc := abi.FuncPCABIInternal(mapdelete)
   701  		racewritepc(unsafe.Pointer(h), callerpc, pc)
   702  		raceReadObjectPC(t.Key, key, callerpc, pc)
   703  	}
   704  	if msanenabled && h != nil {
   705  		msanread(key, t.Key.Size_)
   706  	}
   707  	if asanenabled && h != nil {
   708  		asanread(key, t.Key.Size_)
   709  	}
   710  	if h == nil || h.count == 0 {
   711  		if t.HashMightPanic() {
   712  			t.Hasher(key, 0) // see issue 23734
   713  		}
   714  		return
   715  	}
   716  	if h.flags&hashWriting != 0 {
   717  		fatal("concurrent map writes")
   718  	}
   719  
   720  	hash := t.Hasher(key, uintptr(h.hash0))
   721  
   722  	// Set hashWriting after calling t.hasher, since t.hasher may panic,
   723  	// in which case we have not actually done a write (delete).
   724  	h.flags ^= hashWriting
   725  
   726  	bucket := hash & bucketMask(h.B)
   727  	if h.growing() {
   728  		growWork(t, h, bucket)
   729  	}
   730  	b := (*bmap)(add(h.buckets, bucket*uintptr(t.BucketSize)))
   731  	bOrig := b
   732  	top := tophash(hash)
   733  search:
   734  	for ; b != nil; b = b.overflow(t) {
   735  		for i := uintptr(0); i < bucketCnt; i++ {
   736  			if b.tophash[i] != top {
   737  				if b.tophash[i] == emptyRest {
   738  					break search
   739  				}
   740  				continue
   741  			}
   742  			k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.KeySize))
   743  			k2 := k
   744  			if t.IndirectKey() {
   745  				k2 = *((*unsafe.Pointer)(k2))
   746  			}
   747  			if !t.Key.Equal(key, k2) {
   748  				continue
   749  			}
   750  			// Only clear key if there are pointers in it.
   751  			if t.IndirectKey() {
   752  				*(*unsafe.Pointer)(k) = nil
   753  			} else if t.Key.PtrBytes != 0 {
   754  				memclrHasPointers(k, t.Key.Size_)
   755  			}
   756  			e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
   757  			if t.IndirectElem() {
   758  				*(*unsafe.Pointer)(e) = nil
   759  			} else if t.Elem.PtrBytes != 0 {
   760  				memclrHasPointers(e, t.Elem.Size_)
   761  			} else {
   762  				memclrNoHeapPointers(e, t.Elem.Size_)
   763  			}
   764  			b.tophash[i] = emptyOne
   765  			// If the bucket now ends in a bunch of emptyOne states,
   766  			// change those to emptyRest states.
   767  			// It would be nice to make this a separate function, but
   768  			// for loops are not currently inlineable.
   769  			if i == bucketCnt-1 {
   770  				if b.overflow(t) != nil && b.overflow(t).tophash[0] != emptyRest {
   771  					goto notLast
   772  				}
   773  			} else {
   774  				if b.tophash[i+1] != emptyRest {
   775  					goto notLast
   776  				}
   777  			}
   778  			for {
   779  				b.tophash[i] = emptyRest
   780  				if i == 0 {
   781  					if b == bOrig {
   782  						break // beginning of initial bucket, we're done.
   783  					}
   784  					// Find previous bucket, continue at its last entry.
   785  					c := b
   786  					for b = bOrig; b.overflow(t) != c; b = b.overflow(t) {
   787  					}
   788  					i = bucketCnt - 1
   789  				} else {
   790  					i--
   791  				}
   792  				if b.tophash[i] != emptyOne {
   793  					break
   794  				}
   795  			}
   796  		notLast:
   797  			h.count--
   798  			// Reset the hash seed to make it more difficult for attackers to
   799  			// repeatedly trigger hash collisions. See issue 25237.
   800  			if h.count == 0 {
   801  				h.hash0 = fastrand()
   802  			}
   803  			break search
   804  		}
   805  	}
   806  
   807  	if h.flags&hashWriting == 0 {
   808  		fatal("concurrent map writes")
   809  	}
   810  	h.flags &^= hashWriting
   811  }
   812  
   813  // mapiterinit initializes the hiter struct used for ranging over maps.
   814  // The hiter struct pointed to by 'it' is allocated on the stack
   815  // by the compilers order pass or on the heap by reflect_mapiterinit.
   816  // Both need to have zeroed hiter since the struct contains pointers.
   817  func mapiterinit(t *maptype, h *hmap, it *hiter) {
   818  	if raceenabled && h != nil {
   819  		callerpc := getcallerpc()
   820  		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiterinit))
   821  	}
   822  
   823  	it.t = t
   824  	if h == nil || h.count == 0 {
   825  		return
   826  	}
   827  
   828  	if unsafe.Sizeof(hiter{})/goarch.PtrSize != 12 {
   829  		throw("hash_iter size incorrect") // see cmd/compile/internal/reflectdata/reflect.go
   830  	}
   831  	it.h = h
   832  
   833  	// grab snapshot of bucket state
   834  	it.B = h.B
   835  	it.buckets = h.buckets
   836  	if t.Bucket.PtrBytes == 0 {
   837  		// Allocate the current slice and remember pointers to both current and old.
   838  		// This preserves all relevant overflow buckets alive even if
   839  		// the table grows and/or overflow buckets are added to the table
   840  		// while we are iterating.
   841  		h.createOverflow()
   842  		it.overflow = h.extra.overflow
   843  		it.oldoverflow = h.extra.oldoverflow
   844  	}
   845  
   846  	// decide where to start
   847  	var r uintptr
   848  	if h.B > 31-bucketCntBits {
   849  		r = uintptr(fastrand64())
   850  	} else {
   851  		r = uintptr(fastrand())
   852  	}
   853  	it.startBucket = r & bucketMask(h.B)
   854  	it.offset = uint8(r >> h.B & (bucketCnt - 1))
   855  
   856  	// iterator state
   857  	it.bucket = it.startBucket
   858  
   859  	// Remember we have an iterator.
   860  	// Can run concurrently with another mapiterinit().
   861  	if old := h.flags; old&(iterator|oldIterator) != iterator|oldIterator {
   862  		atomic.Or8(&h.flags, iterator|oldIterator)
   863  	}
   864  
   865  	mapiternext(it)
   866  }
   867  
   868  func mapiternext(it *hiter) {
   869  	h := it.h
   870  	if raceenabled {
   871  		callerpc := getcallerpc()
   872  		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapiternext))
   873  	}
   874  	if h.flags&hashWriting != 0 {
   875  		fatal("concurrent map iteration and map write")
   876  	}
   877  	t := it.t
   878  	bucket := it.bucket
   879  	b := it.bptr
   880  	i := it.i
   881  	checkBucket := it.checkBucket
   882  
   883  next:
   884  	if b == nil {
   885  		if bucket == it.startBucket && it.wrapped {
   886  			// end of iteration
   887  			it.key = nil
   888  			it.elem = nil
   889  			return
   890  		}
   891  		if h.growing() && it.B == h.B {
   892  			// Iterator was started in the middle of a grow, and the grow isn't done yet.
   893  			// If the bucket we're looking at hasn't been filled in yet (i.e. the old
   894  			// bucket hasn't been evacuated) then we need to iterate through the old
   895  			// bucket and only return the ones that will be migrated to this bucket.
   896  			oldbucket := bucket & it.h.oldbucketmask()
   897  			b = (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.BucketSize)))
   898  			if !evacuated(b) {
   899  				checkBucket = bucket
   900  			} else {
   901  				b = (*bmap)(add(it.buckets, bucket*uintptr(t.BucketSize)))
   902  				checkBucket = noCheck
   903  			}
   904  		} else {
   905  			b = (*bmap)(add(it.buckets, bucket*uintptr(t.BucketSize)))
   906  			checkBucket = noCheck
   907  		}
   908  		bucket++
   909  		if bucket == bucketShift(it.B) {
   910  			bucket = 0
   911  			it.wrapped = true
   912  		}
   913  		i = 0
   914  	}
   915  	for ; i < bucketCnt; i++ {
   916  		offi := (i + it.offset) & (bucketCnt - 1)
   917  		if isEmpty(b.tophash[offi]) || b.tophash[offi] == evacuatedEmpty {
   918  			// TODO: emptyRest is hard to use here, as we start iterating
   919  			// in the middle of a bucket. It's feasible, just tricky.
   920  			continue
   921  		}
   922  		k := add(unsafe.Pointer(b), dataOffset+uintptr(offi)*uintptr(t.KeySize))
   923  		if t.IndirectKey() {
   924  			k = *((*unsafe.Pointer)(k))
   925  		}
   926  		e := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+uintptr(offi)*uintptr(t.ValueSize))
   927  		if checkBucket != noCheck && !h.sameSizeGrow() {
   928  			// Special case: iterator was started during a grow to a larger size
   929  			// and the grow is not done yet. We're working on a bucket whose
   930  			// oldbucket has not been evacuated yet. Or at least, it wasn't
   931  			// evacuated when we started the bucket. So we're iterating
   932  			// through the oldbucket, skipping any keys that will go
   933  			// to the other new bucket (each oldbucket expands to two
   934  			// buckets during a grow).
   935  			if t.ReflexiveKey() || t.Key.Equal(k, k) {
   936  				// If the item in the oldbucket is not destined for
   937  				// the current new bucket in the iteration, skip it.
   938  				hash := t.Hasher(k, uintptr(h.hash0))
   939  				if hash&bucketMask(it.B) != checkBucket {
   940  					continue
   941  				}
   942  			} else {
   943  				// Hash isn't repeatable if k != k (NaNs).  We need a
   944  				// repeatable and randomish choice of which direction
   945  				// to send NaNs during evacuation. We'll use the low
   946  				// bit of tophash to decide which way NaNs go.
   947  				// NOTE: this case is why we need two evacuate tophash
   948  				// values, evacuatedX and evacuatedY, that differ in
   949  				// their low bit.
   950  				if checkBucket>>(it.B-1) != uintptr(b.tophash[offi]&1) {
   951  					continue
   952  				}
   953  			}
   954  		}
   955  		if (b.tophash[offi] != evacuatedX && b.tophash[offi] != evacuatedY) ||
   956  			!(t.ReflexiveKey() || t.Key.Equal(k, k)) {
   957  			// This is the golden data, we can return it.
   958  			// OR
   959  			// key!=key, so the entry can't be deleted or updated, so we can just return it.
   960  			// That's lucky for us because when key!=key we can't look it up successfully.
   961  			it.key = k
   962  			if t.IndirectElem() {
   963  				e = *((*unsafe.Pointer)(e))
   964  			}
   965  			it.elem = e
   966  		} else {
   967  			// The hash table has grown since the iterator was started.
   968  			// The golden data for this key is now somewhere else.
   969  			// Check the current hash table for the data.
   970  			// This code handles the case where the key
   971  			// has been deleted, updated, or deleted and reinserted.
   972  			// NOTE: we need to regrab the key as it has potentially been
   973  			// updated to an equal() but not identical key (e.g. +0.0 vs -0.0).
   974  			rk, re := mapaccessK(t, h, k)
   975  			if rk == nil {
   976  				continue // key has been deleted
   977  			}
   978  			it.key = rk
   979  			it.elem = re
   980  		}
   981  		it.bucket = bucket
   982  		if it.bptr != b { // avoid unnecessary write barrier; see issue 14921
   983  			it.bptr = b
   984  		}
   985  		it.i = i + 1
   986  		it.checkBucket = checkBucket
   987  		return
   988  	}
   989  	b = b.overflow(t)
   990  	i = 0
   991  	goto next
   992  }
   993  
   994  // mapclear deletes all keys from a map.
   995  func mapclear(t *maptype, h *hmap) {
   996  	if raceenabled && h != nil {
   997  		callerpc := getcallerpc()
   998  		pc := abi.FuncPCABIInternal(mapclear)
   999  		racewritepc(unsafe.Pointer(h), callerpc, pc)
  1000  	}
  1001  
  1002  	if h == nil || h.count == 0 {
  1003  		return
  1004  	}
  1005  
  1006  	if h.flags&hashWriting != 0 {
  1007  		fatal("concurrent map writes")
  1008  	}
  1009  
  1010  	h.flags ^= hashWriting
  1011  
  1012  	// Mark buckets empty, so existing iterators can be terminated, see issue #59411.
  1013  	markBucketsEmpty := func(bucket unsafe.Pointer, mask uintptr) {
  1014  		for i := uintptr(0); i <= mask; i++ {
  1015  			b := (*bmap)(add(bucket, i*uintptr(t.BucketSize)))
  1016  			for ; b != nil; b = b.overflow(t) {
  1017  				for i := uintptr(0); i < bucketCnt; i++ {
  1018  					b.tophash[i] = emptyRest
  1019  				}
  1020  			}
  1021  		}
  1022  	}
  1023  	markBucketsEmpty(h.buckets, bucketMask(h.B))
  1024  	if oldBuckets := h.oldbuckets; oldBuckets != nil {
  1025  		markBucketsEmpty(oldBuckets, h.oldbucketmask())
  1026  	}
  1027  
  1028  	h.flags &^= sameSizeGrow
  1029  	h.oldbuckets = nil
  1030  	h.nevacuate = 0
  1031  	h.noverflow = 0
  1032  	h.count = 0
  1033  
  1034  	// Reset the hash seed to make it more difficult for attackers to
  1035  	// repeatedly trigger hash collisions. See issue 25237.
  1036  	h.hash0 = fastrand()
  1037  
  1038  	// Keep the mapextra allocation but clear any extra information.
  1039  	if h.extra != nil {
  1040  		*h.extra = mapextra{}
  1041  	}
  1042  
  1043  	// makeBucketArray clears the memory pointed to by h.buckets
  1044  	// and recovers any overflow buckets by generating them
  1045  	// as if h.buckets was newly alloced.
  1046  	_, nextOverflow := makeBucketArray(t, h.B, h.buckets)
  1047  	if nextOverflow != nil {
  1048  		// If overflow buckets are created then h.extra
  1049  		// will have been allocated during initial bucket creation.
  1050  		h.extra.nextOverflow = nextOverflow
  1051  	}
  1052  
  1053  	if h.flags&hashWriting == 0 {
  1054  		fatal("concurrent map writes")
  1055  	}
  1056  	h.flags &^= hashWriting
  1057  }
  1058  
  1059  func hashGrow(t *maptype, h *hmap) {
  1060  	// If we've hit the load factor, get bigger.
  1061  	// Otherwise, there are too many overflow buckets,
  1062  	// so keep the same number of buckets and "grow" laterally.
  1063  	bigger := uint8(1)
  1064  	if !overLoadFactor(h.count+1, h.B) {
  1065  		bigger = 0
  1066  		h.flags |= sameSizeGrow
  1067  	}
  1068  	oldbuckets := h.buckets
  1069  	newbuckets, nextOverflow := makeBucketArray(t, h.B+bigger, nil)
  1070  
  1071  	flags := h.flags &^ (iterator | oldIterator)
  1072  	if h.flags&iterator != 0 {
  1073  		flags |= oldIterator
  1074  	}
  1075  	// commit the grow (atomic wrt gc)
  1076  	h.B += bigger
  1077  	h.flags = flags
  1078  	h.oldbuckets = oldbuckets
  1079  	h.buckets = newbuckets
  1080  	h.nevacuate = 0
  1081  	h.noverflow = 0
  1082  
  1083  	if h.extra != nil && h.extra.overflow != nil {
  1084  		// Promote current overflow buckets to the old generation.
  1085  		if h.extra.oldoverflow != nil {
  1086  			throw("oldoverflow is not nil")
  1087  		}
  1088  		h.extra.oldoverflow = h.extra.overflow
  1089  		h.extra.overflow = nil
  1090  	}
  1091  	if nextOverflow != nil {
  1092  		if h.extra == nil {
  1093  			h.extra = new(mapextra)
  1094  		}
  1095  		h.extra.nextOverflow = nextOverflow
  1096  	}
  1097  
  1098  	// the actual copying of the hash table data is done incrementally
  1099  	// by growWork() and evacuate().
  1100  }
  1101  
  1102  // overLoadFactor reports whether count items placed in 1<<B buckets is over loadFactor.
  1103  func overLoadFactor(count int, B uint8) bool {
  1104  	return count > bucketCnt && uintptr(count) > loadFactorNum*(bucketShift(B)/loadFactorDen)
  1105  }
  1106  
  1107  // tooManyOverflowBuckets reports whether noverflow buckets is too many for a map with 1<<B buckets.
  1108  // Note that most of these overflow buckets must be in sparse use;
  1109  // if use was dense, then we'd have already triggered regular map growth.
  1110  func tooManyOverflowBuckets(noverflow uint16, B uint8) bool {
  1111  	// If the threshold is too low, we do extraneous work.
  1112  	// If the threshold is too high, maps that grow and shrink can hold on to lots of unused memory.
  1113  	// "too many" means (approximately) as many overflow buckets as regular buckets.
  1114  	// See incrnoverflow for more details.
  1115  	if B > 15 {
  1116  		B = 15
  1117  	}
  1118  	// The compiler doesn't see here that B < 16; mask B to generate shorter shift code.
  1119  	return noverflow >= uint16(1)<<(B&15)
  1120  }
  1121  
  1122  // growing reports whether h is growing. The growth may be to the same size or bigger.
  1123  func (h *hmap) growing() bool {
  1124  	return h.oldbuckets != nil
  1125  }
  1126  
  1127  // sameSizeGrow reports whether the current growth is to a map of the same size.
  1128  func (h *hmap) sameSizeGrow() bool {
  1129  	return h.flags&sameSizeGrow != 0
  1130  }
  1131  
  1132  // noldbuckets calculates the number of buckets prior to the current map growth.
  1133  func (h *hmap) noldbuckets() uintptr {
  1134  	oldB := h.B
  1135  	if !h.sameSizeGrow() {
  1136  		oldB--
  1137  	}
  1138  	return bucketShift(oldB)
  1139  }
  1140  
  1141  // oldbucketmask provides a mask that can be applied to calculate n % noldbuckets().
  1142  func (h *hmap) oldbucketmask() uintptr {
  1143  	return h.noldbuckets() - 1
  1144  }
  1145  
  1146  func growWork(t *maptype, h *hmap, bucket uintptr) {
  1147  	// make sure we evacuate the oldbucket corresponding
  1148  	// to the bucket we're about to use
  1149  	evacuate(t, h, bucket&h.oldbucketmask())
  1150  
  1151  	// evacuate one more oldbucket to make progress on growing
  1152  	if h.growing() {
  1153  		evacuate(t, h, h.nevacuate)
  1154  	}
  1155  }
  1156  
  1157  func bucketEvacuated(t *maptype, h *hmap, bucket uintptr) bool {
  1158  	b := (*bmap)(add(h.oldbuckets, bucket*uintptr(t.BucketSize)))
  1159  	return evacuated(b)
  1160  }
  1161  
  1162  // evacDst is an evacuation destination.
  1163  type evacDst struct {
  1164  	b *bmap          // current destination bucket
  1165  	i int            // key/elem index into b
  1166  	k unsafe.Pointer // pointer to current key storage
  1167  	e unsafe.Pointer // pointer to current elem storage
  1168  }
  1169  
  1170  func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
  1171  	b := (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.BucketSize)))
  1172  	newbit := h.noldbuckets()
  1173  	if !evacuated(b) {
  1174  		// TODO: reuse overflow buckets instead of using new ones, if there
  1175  		// is no iterator using the old buckets.  (If !oldIterator.)
  1176  
  1177  		// xy contains the x and y (low and high) evacuation destinations.
  1178  		var xy [2]evacDst
  1179  		x := &xy[0]
  1180  		x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.BucketSize)))
  1181  		x.k = add(unsafe.Pointer(x.b), dataOffset)
  1182  		x.e = add(x.k, bucketCnt*uintptr(t.KeySize))
  1183  
  1184  		if !h.sameSizeGrow() {
  1185  			// Only calculate y pointers if we're growing bigger.
  1186  			// Otherwise GC can see bad pointers.
  1187  			y := &xy[1]
  1188  			y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.BucketSize)))
  1189  			y.k = add(unsafe.Pointer(y.b), dataOffset)
  1190  			y.e = add(y.k, bucketCnt*uintptr(t.KeySize))
  1191  		}
  1192  
  1193  		for ; b != nil; b = b.overflow(t) {
  1194  			k := add(unsafe.Pointer(b), dataOffset)
  1195  			e := add(k, bucketCnt*uintptr(t.KeySize))
  1196  			for i := 0; i < bucketCnt; i, k, e = i+1, add(k, uintptr(t.KeySize)), add(e, uintptr(t.ValueSize)) {
  1197  				top := b.tophash[i]
  1198  				if isEmpty(top) {
  1199  					b.tophash[i] = evacuatedEmpty
  1200  					continue
  1201  				}
  1202  				if top < minTopHash {
  1203  					throw("bad map state")
  1204  				}
  1205  				k2 := k
  1206  				if t.IndirectKey() {
  1207  					k2 = *((*unsafe.Pointer)(k2))
  1208  				}
  1209  				var useY uint8
  1210  				if !h.sameSizeGrow() {
  1211  					// Compute hash to make our evacuation decision (whether we need
  1212  					// to send this key/elem to bucket x or bucket y).
  1213  					hash := t.Hasher(k2, uintptr(h.hash0))
  1214  					if h.flags&iterator != 0 && !t.ReflexiveKey() && !t.Key.Equal(k2, k2) {
  1215  						// If key != key (NaNs), then the hash could be (and probably
  1216  						// will be) entirely different from the old hash. Moreover,
  1217  						// it isn't reproducible. Reproducibility is required in the
  1218  						// presence of iterators, as our evacuation decision must
  1219  						// match whatever decision the iterator made.
  1220  						// Fortunately, we have the freedom to send these keys either
  1221  						// way. Also, tophash is meaningless for these kinds of keys.
  1222  						// We let the low bit of tophash drive the evacuation decision.
  1223  						// We recompute a new random tophash for the next level so
  1224  						// these keys will get evenly distributed across all buckets
  1225  						// after multiple grows.
  1226  						useY = top & 1
  1227  						top = tophash(hash)
  1228  					} else {
  1229  						if hash&newbit != 0 {
  1230  							useY = 1
  1231  						}
  1232  					}
  1233  				}
  1234  
  1235  				if evacuatedX+1 != evacuatedY || evacuatedX^1 != evacuatedY {
  1236  					throw("bad evacuatedN")
  1237  				}
  1238  
  1239  				b.tophash[i] = evacuatedX + useY // evacuatedX + 1 == evacuatedY
  1240  				dst := &xy[useY]                 // evacuation destination
  1241  
  1242  				if dst.i == bucketCnt {
  1243  					dst.b = h.newoverflow(t, dst.b)
  1244  					dst.i = 0
  1245  					dst.k = add(unsafe.Pointer(dst.b), dataOffset)
  1246  					dst.e = add(dst.k, bucketCnt*uintptr(t.KeySize))
  1247  				}
  1248  				dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
  1249  				if t.IndirectKey() {
  1250  					*(*unsafe.Pointer)(dst.k) = k2 // copy pointer
  1251  				} else {
  1252  					typedmemmove(t.Key, dst.k, k) // copy elem
  1253  				}
  1254  				if t.IndirectElem() {
  1255  					*(*unsafe.Pointer)(dst.e) = *(*unsafe.Pointer)(e)
  1256  				} else {
  1257  					typedmemmove(t.Elem, dst.e, e)
  1258  				}
  1259  				dst.i++
  1260  				// These updates might push these pointers past the end of the
  1261  				// key or elem arrays.  That's ok, as we have the overflow pointer
  1262  				// at the end of the bucket to protect against pointing past the
  1263  				// end of the bucket.
  1264  				dst.k = add(dst.k, uintptr(t.KeySize))
  1265  				dst.e = add(dst.e, uintptr(t.ValueSize))
  1266  			}
  1267  		}
  1268  		// Unlink the overflow buckets & clear key/elem to help GC.
  1269  		if h.flags&oldIterator == 0 && t.Bucket.PtrBytes != 0 {
  1270  			b := add(h.oldbuckets, oldbucket*uintptr(t.BucketSize))
  1271  			// Preserve b.tophash because the evacuation
  1272  			// state is maintained there.
  1273  			ptr := add(b, dataOffset)
  1274  			n := uintptr(t.BucketSize) - dataOffset
  1275  			memclrHasPointers(ptr, n)
  1276  		}
  1277  	}
  1278  
  1279  	if oldbucket == h.nevacuate {
  1280  		advanceEvacuationMark(h, t, newbit)
  1281  	}
  1282  }
  1283  
  1284  func advanceEvacuationMark(h *hmap, t *maptype, newbit uintptr) {
  1285  	h.nevacuate++
  1286  	// Experiments suggest that 1024 is overkill by at least an order of magnitude.
  1287  	// Put it in there as a safeguard anyway, to ensure O(1) behavior.
  1288  	stop := h.nevacuate + 1024
  1289  	if stop > newbit {
  1290  		stop = newbit
  1291  	}
  1292  	for h.nevacuate != stop && bucketEvacuated(t, h, h.nevacuate) {
  1293  		h.nevacuate++
  1294  	}
  1295  	if h.nevacuate == newbit { // newbit == # of oldbuckets
  1296  		// Growing is all done. Free old main bucket array.
  1297  		h.oldbuckets = nil
  1298  		// Can discard old overflow buckets as well.
  1299  		// If they are still referenced by an iterator,
  1300  		// then the iterator holds a pointers to the slice.
  1301  		if h.extra != nil {
  1302  			h.extra.oldoverflow = nil
  1303  		}
  1304  		h.flags &^= sameSizeGrow
  1305  	}
  1306  }
  1307  
  1308  // Reflect stubs. Called from ../reflect/asm_*.s
  1309  
  1310  //go:linkname reflect_makemap reflect.makemap
  1311  func reflect_makemap(t *maptype, cap int) *hmap {
  1312  	// Check invariants and reflects math.
  1313  	if t.Key.Equal == nil {
  1314  		throw("runtime.reflect_makemap: unsupported map key type")
  1315  	}
  1316  	if t.Key.Size_ > maxKeySize && (!t.IndirectKey() || t.KeySize != uint8(goarch.PtrSize)) ||
  1317  		t.Key.Size_ <= maxKeySize && (t.IndirectKey() || t.KeySize != uint8(t.Key.Size_)) {
  1318  		throw("key size wrong")
  1319  	}
  1320  	if t.Elem.Size_ > maxElemSize && (!t.IndirectElem() || t.ValueSize != uint8(goarch.PtrSize)) ||
  1321  		t.Elem.Size_ <= maxElemSize && (t.IndirectElem() || t.ValueSize != uint8(t.Elem.Size_)) {
  1322  		throw("elem size wrong")
  1323  	}
  1324  	if t.Key.Align_ > bucketCnt {
  1325  		throw("key align too big")
  1326  	}
  1327  	if t.Elem.Align_ > bucketCnt {
  1328  		throw("elem align too big")
  1329  	}
  1330  	if t.Key.Size_%uintptr(t.Key.Align_) != 0 {
  1331  		throw("key size not a multiple of key align")
  1332  	}
  1333  	if t.Elem.Size_%uintptr(t.Elem.Align_) != 0 {
  1334  		throw("elem size not a multiple of elem align")
  1335  	}
  1336  	if bucketCnt < 8 {
  1337  		throw("bucketsize too small for proper alignment")
  1338  	}
  1339  	if dataOffset%uintptr(t.Key.Align_) != 0 {
  1340  		throw("need padding in bucket (key)")
  1341  	}
  1342  	if dataOffset%uintptr(t.Elem.Align_) != 0 {
  1343  		throw("need padding in bucket (elem)")
  1344  	}
  1345  
  1346  	return makemap(t, cap, nil)
  1347  }
  1348  
  1349  //go:linkname reflect_mapaccess reflect.mapaccess
  1350  func reflect_mapaccess(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
  1351  	elem, ok := mapaccess2(t, h, key)
  1352  	if !ok {
  1353  		// reflect wants nil for a missing element
  1354  		elem = nil
  1355  	}
  1356  	return elem
  1357  }
  1358  
  1359  //go:linkname reflect_mapaccess_faststr reflect.mapaccess_faststr
  1360  func reflect_mapaccess_faststr(t *maptype, h *hmap, key string) unsafe.Pointer {
  1361  	elem, ok := mapaccess2_faststr(t, h, key)
  1362  	if !ok {
  1363  		// reflect wants nil for a missing element
  1364  		elem = nil
  1365  	}
  1366  	return elem
  1367  }
  1368  
  1369  //go:linkname reflect_mapassign reflect.mapassign0
  1370  func reflect_mapassign(t *maptype, h *hmap, key unsafe.Pointer, elem unsafe.Pointer) {
  1371  	p := mapassign(t, h, key)
  1372  	typedmemmove(t.Elem, p, elem)
  1373  }
  1374  
  1375  //go:linkname reflect_mapassign_faststr reflect.mapassign_faststr0
  1376  func reflect_mapassign_faststr(t *maptype, h *hmap, key string, elem unsafe.Pointer) {
  1377  	p := mapassign_faststr(t, h, key)
  1378  	typedmemmove(t.Elem, p, elem)
  1379  }
  1380  
  1381  //go:linkname reflect_mapdelete reflect.mapdelete
  1382  func reflect_mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
  1383  	mapdelete(t, h, key)
  1384  }
  1385  
  1386  //go:linkname reflect_mapdelete_faststr reflect.mapdelete_faststr
  1387  func reflect_mapdelete_faststr(t *maptype, h *hmap, key string) {
  1388  	mapdelete_faststr(t, h, key)
  1389  }
  1390  
  1391  //go:linkname reflect_mapiterinit reflect.mapiterinit
  1392  func reflect_mapiterinit(t *maptype, h *hmap, it *hiter) {
  1393  	mapiterinit(t, h, it)
  1394  }
  1395  
  1396  //go:linkname reflect_mapiternext reflect.mapiternext
  1397  func reflect_mapiternext(it *hiter) {
  1398  	mapiternext(it)
  1399  }
  1400  
  1401  //go:linkname reflect_mapiterkey reflect.mapiterkey
  1402  func reflect_mapiterkey(it *hiter) unsafe.Pointer {
  1403  	return it.key
  1404  }
  1405  
  1406  //go:linkname reflect_mapiterelem reflect.mapiterelem
  1407  func reflect_mapiterelem(it *hiter) unsafe.Pointer {
  1408  	return it.elem
  1409  }
  1410  
  1411  //go:linkname reflect_maplen reflect.maplen
  1412  func reflect_maplen(h *hmap) int {
  1413  	if h == nil {
  1414  		return 0
  1415  	}
  1416  	if raceenabled {
  1417  		callerpc := getcallerpc()
  1418  		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
  1419  	}
  1420  	return h.count
  1421  }
  1422  
  1423  //go:linkname reflect_mapclear reflect.mapclear
  1424  func reflect_mapclear(t *maptype, h *hmap) {
  1425  	mapclear(t, h)
  1426  }
  1427  
  1428  //go:linkname reflectlite_maplen internal/reflectlite.maplen
  1429  func reflectlite_maplen(h *hmap) int {
  1430  	if h == nil {
  1431  		return 0
  1432  	}
  1433  	if raceenabled {
  1434  		callerpc := getcallerpc()
  1435  		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(reflect_maplen))
  1436  	}
  1437  	return h.count
  1438  }
  1439  
  1440  const maxZero = 1024 // must match value in reflect/value.go:maxZero cmd/compile/internal/gc/walk.go:zeroValSize
  1441  var zeroVal [maxZero]byte
  1442  
  1443  // mapinitnoop is a no-op function known the Go linker; if a given global
  1444  // map (of the right size) is determined to be dead, the linker will
  1445  // rewrite the relocation (from the package init func) from the outlined
  1446  // map init function to this symbol. Defined in assembly so as to avoid
  1447  // complications with instrumentation (coverage, etc).
  1448  func mapinitnoop()
  1449  
  1450  // mapclone for implementing maps.Clone
  1451  //
  1452  //go:linkname mapclone maps.clone
  1453  func mapclone(m any) any {
  1454  	e := efaceOf(&m)
  1455  	e.data = unsafe.Pointer(mapclone2((*maptype)(unsafe.Pointer(e._type)), (*hmap)(e.data)))
  1456  	return m
  1457  }
  1458  
  1459  // moveToBmap moves a bucket from src to dst. It returns the destination bucket or new destination bucket if it overflows
  1460  // and the pos that the next key/value will be written, if pos == bucketCnt means needs to written in overflow bucket.
  1461  func moveToBmap(t *maptype, h *hmap, dst *bmap, pos int, src *bmap) (*bmap, int) {
  1462  	for i := 0; i < bucketCnt; i++ {
  1463  		if isEmpty(src.tophash[i]) {
  1464  			continue
  1465  		}
  1466  
  1467  		for ; pos < bucketCnt; pos++ {
  1468  			if isEmpty(dst.tophash[pos]) {
  1469  				break
  1470  			}
  1471  		}
  1472  
  1473  		if pos == bucketCnt {
  1474  			dst = h.newoverflow(t, dst)
  1475  			pos = 0
  1476  		}
  1477  
  1478  		srcK := add(unsafe.Pointer(src), dataOffset+uintptr(i)*uintptr(t.KeySize))
  1479  		srcEle := add(unsafe.Pointer(src), dataOffset+bucketCnt*uintptr(t.KeySize)+uintptr(i)*uintptr(t.ValueSize))
  1480  		dstK := add(unsafe.Pointer(dst), dataOffset+uintptr(pos)*uintptr(t.KeySize))
  1481  		dstEle := add(unsafe.Pointer(dst), dataOffset+bucketCnt*uintptr(t.KeySize)+uintptr(pos)*uintptr(t.ValueSize))
  1482  
  1483  		dst.tophash[pos] = src.tophash[i]
  1484  		if t.IndirectKey() {
  1485  			*(*unsafe.Pointer)(dstK) = *(*unsafe.Pointer)(srcK)
  1486  		} else {
  1487  			typedmemmove(t.Key, dstK, srcK)
  1488  		}
  1489  		if t.IndirectElem() {
  1490  			*(*unsafe.Pointer)(dstEle) = *(*unsafe.Pointer)(srcEle)
  1491  		} else {
  1492  			typedmemmove(t.Elem, dstEle, srcEle)
  1493  		}
  1494  		pos++
  1495  		h.count++
  1496  	}
  1497  	return dst, pos
  1498  }
  1499  
  1500  func mapclone2(t *maptype, src *hmap) *hmap {
  1501  	dst := makemap(t, src.count, nil)
  1502  	dst.hash0 = src.hash0
  1503  	dst.nevacuate = 0
  1504  	//flags do not need to be copied here, just like a new map has no flags.
  1505  
  1506  	if src.count == 0 {
  1507  		return dst
  1508  	}
  1509  
  1510  	if src.flags&hashWriting != 0 {
  1511  		fatal("concurrent map clone and map write")
  1512  	}
  1513  
  1514  	if src.B == 0 {
  1515  		dst.buckets = newobject(t.Bucket)
  1516  		dst.count = src.count
  1517  		typedmemmove(t.Bucket, dst.buckets, src.buckets)
  1518  		return dst
  1519  	}
  1520  
  1521  	//src.B != 0
  1522  	if dst.B == 0 {
  1523  		dst.buckets = newobject(t.Bucket)
  1524  	}
  1525  	dstArraySize := int(bucketShift(dst.B))
  1526  	srcArraySize := int(bucketShift(src.B))
  1527  	for i := 0; i < dstArraySize; i++ {
  1528  		dstBmap := (*bmap)(add(dst.buckets, uintptr(i*int(t.BucketSize))))
  1529  		pos := 0
  1530  		for j := 0; j < srcArraySize; j += dstArraySize {
  1531  			srcBmap := (*bmap)(add(src.buckets, uintptr((i+j)*int(t.BucketSize))))
  1532  			for srcBmap != nil {
  1533  				dstBmap, pos = moveToBmap(t, dst, dstBmap, pos, srcBmap)
  1534  				srcBmap = srcBmap.overflow(t)
  1535  			}
  1536  		}
  1537  	}
  1538  
  1539  	if src.oldbuckets == nil {
  1540  		return dst
  1541  	}
  1542  
  1543  	oldB := src.B
  1544  	srcOldbuckets := src.oldbuckets
  1545  	if !src.sameSizeGrow() {
  1546  		oldB--
  1547  	}
  1548  	oldSrcArraySize := int(bucketShift(oldB))
  1549  
  1550  	for i := 0; i < oldSrcArraySize; i++ {
  1551  		srcBmap := (*bmap)(add(srcOldbuckets, uintptr(i*int(t.BucketSize))))
  1552  		if evacuated(srcBmap) {
  1553  			continue
  1554  		}
  1555  
  1556  		if oldB >= dst.B { // main bucket bits in dst is less than oldB bits in src
  1557  			dstBmap := (*bmap)(add(dst.buckets, (uintptr(i)&bucketMask(dst.B))*uintptr(t.BucketSize)))
  1558  			for dstBmap.overflow(t) != nil {
  1559  				dstBmap = dstBmap.overflow(t)
  1560  			}
  1561  			pos := 0
  1562  			for srcBmap != nil {
  1563  				dstBmap, pos = moveToBmap(t, dst, dstBmap, pos, srcBmap)
  1564  				srcBmap = srcBmap.overflow(t)
  1565  			}
  1566  			continue
  1567  		}
  1568  
  1569  		for srcBmap != nil {
  1570  			// move from oldBlucket to new bucket
  1571  			for i := uintptr(0); i < bucketCnt; i++ {
  1572  				if isEmpty(srcBmap.tophash[i]) {
  1573  					continue
  1574  				}
  1575  
  1576  				if src.flags&hashWriting != 0 {
  1577  					fatal("concurrent map clone and map write")
  1578  				}
  1579  
  1580  				srcK := add(unsafe.Pointer(srcBmap), dataOffset+i*uintptr(t.KeySize))
  1581  				if t.IndirectKey() {
  1582  					srcK = *((*unsafe.Pointer)(srcK))
  1583  				}
  1584  
  1585  				srcEle := add(unsafe.Pointer(srcBmap), dataOffset+bucketCnt*uintptr(t.KeySize)+i*uintptr(t.ValueSize))
  1586  				if t.IndirectElem() {
  1587  					srcEle = *((*unsafe.Pointer)(srcEle))
  1588  				}
  1589  				dstEle := mapassign(t, dst, srcK)
  1590  				typedmemmove(t.Elem, dstEle, srcEle)
  1591  			}
  1592  			srcBmap = srcBmap.overflow(t)
  1593  		}
  1594  	}
  1595  	return dst
  1596  }
  1597  
  1598  // keys for implementing maps.keys
  1599  //
  1600  //go:linkname keys maps.keys
  1601  func keys(m any, p unsafe.Pointer) {
  1602  	e := efaceOf(&m)
  1603  	t := (*maptype)(unsafe.Pointer(e._type))
  1604  	h := (*hmap)(e.data)
  1605  
  1606  	if h == nil || h.count == 0 {
  1607  		return
  1608  	}
  1609  	s := (*slice)(p)
  1610  	r := int(fastrand())
  1611  	offset := uint8(r >> h.B & (bucketCnt - 1))
  1612  	if h.B == 0 {
  1613  		copyKeys(t, h, (*bmap)(h.buckets), s, offset)
  1614  		return
  1615  	}
  1616  	arraySize := int(bucketShift(h.B))
  1617  	buckets := h.buckets
  1618  	for i := 0; i < arraySize; i++ {
  1619  		bucket := (i + r) & (arraySize - 1)
  1620  		b := (*bmap)(add(buckets, uintptr(bucket)*uintptr(t.BucketSize)))
  1621  		copyKeys(t, h, b, s, offset)
  1622  	}
  1623  
  1624  	if h.growing() {
  1625  		oldArraySize := int(h.noldbuckets())
  1626  		for i := 0; i < oldArraySize; i++ {
  1627  			bucket := (i + r) & (oldArraySize - 1)
  1628  			b := (*bmap)(add(h.oldbuckets, uintptr(bucket)*uintptr(t.BucketSize)))
  1629  			if evacuated(b) {
  1630  				continue
  1631  			}
  1632  			copyKeys(t, h, b, s, offset)
  1633  		}
  1634  	}
  1635  	return
  1636  }
  1637  
  1638  func copyKeys(t *maptype, h *hmap, b *bmap, s *slice, offset uint8) {
  1639  	for b != nil {
  1640  		for i := uintptr(0); i < bucketCnt; i++ {
  1641  			offi := (i + uintptr(offset)) & (bucketCnt - 1)
  1642  			if isEmpty(b.tophash[offi]) {
  1643  				continue
  1644  			}
  1645  			if h.flags&hashWriting != 0 {
  1646  				fatal("concurrent map read and map write")
  1647  			}
  1648  			k := add(unsafe.Pointer(b), dataOffset+offi*uintptr(t.KeySize))
  1649  			if t.IndirectKey() {
  1650  				k = *((*unsafe.Pointer)(k))
  1651  			}
  1652  			if s.len >= s.cap {
  1653  				fatal("concurrent map read and map write")
  1654  			}
  1655  			typedmemmove(t.Key, add(s.array, uintptr(s.len)*uintptr(t.KeySize)), k)
  1656  			s.len++
  1657  		}
  1658  		b = b.overflow(t)
  1659  	}
  1660  }
  1661  
  1662  // values for implementing maps.values
  1663  //
  1664  //go:linkname values maps.values
  1665  func values(m any, p unsafe.Pointer) {
  1666  	e := efaceOf(&m)
  1667  	t := (*maptype)(unsafe.Pointer(e._type))
  1668  	h := (*hmap)(e.data)
  1669  	if h == nil || h.count == 0 {
  1670  		return
  1671  	}
  1672  	s := (*slice)(p)
  1673  	r := int(fastrand())
  1674  	offset := uint8(r >> h.B & (bucketCnt - 1))
  1675  	if h.B == 0 {
  1676  		copyValues(t, h, (*bmap)(h.buckets), s, offset)
  1677  		return
  1678  	}
  1679  	arraySize := int(bucketShift(h.B))
  1680  	buckets := h.buckets
  1681  	for i := 0; i < arraySize; i++ {
  1682  		bucket := (i + r) & (arraySize - 1)
  1683  		b := (*bmap)(add(buckets, uintptr(bucket)*uintptr(t.BucketSize)))
  1684  		copyValues(t, h, b, s, offset)
  1685  	}
  1686  
  1687  	if h.growing() {
  1688  		oldArraySize := int(h.noldbuckets())
  1689  		for i := 0; i < oldArraySize; i++ {
  1690  			bucket := (i + r) & (oldArraySize - 1)
  1691  			b := (*bmap)(add(h.oldbuckets, uintptr(bucket)*uintptr(t.BucketSize)))
  1692  			if evacuated(b) {
  1693  				continue
  1694  			}
  1695  			copyValues(t, h, b, s, offset)
  1696  		}
  1697  	}
  1698  	return
  1699  }
  1700  
  1701  func copyValues(t *maptype, h *hmap, b *bmap, s *slice, offset uint8) {
  1702  	for b != nil {
  1703  		for i := uintptr(0); i < bucketCnt; i++ {
  1704  			offi := (i + uintptr(offset)) & (bucketCnt - 1)
  1705  			if isEmpty(b.tophash[offi]) {
  1706  				continue
  1707  			}
  1708  
  1709  			if h.flags&hashWriting != 0 {
  1710  				fatal("concurrent map read and map write")
  1711  			}
  1712  
  1713  			ele := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.KeySize)+offi*uintptr(t.ValueSize))
  1714  			if t.IndirectElem() {
  1715  				ele = *((*unsafe.Pointer)(ele))
  1716  			}
  1717  			if s.len >= s.cap {
  1718  				fatal("concurrent map read and map write")
  1719  			}
  1720  			typedmemmove(t.Elem, add(s.array, uintptr(s.len)*uintptr(t.ValueSize)), ele)
  1721  			s.len++
  1722  		}
  1723  		b = b.overflow(t)
  1724  	}
  1725  }
  1726  */