runtime_fast32.go

     1  // Copyright 2024 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 maps
     6  
     7  import (
     8  	"internal/abi"
     9  	"internal/race"
    10  	"internal/runtime/sys"
    11  	"unsafe"
    12  )
    13  
    14  //go:linkname runtime_mapaccess1_fast32 runtime.mapaccess1_fast32
    15  func runtime_mapaccess1_fast32(typ *abi.MapType, m *Map, key uint32) unsafe.Pointer {
    16  	if race.Enabled && m != nil {
    17  		callerpc := sys.GetCallerPC()
    18  		pc := abi.FuncPCABIInternal(runtime_mapaccess1_fast32)
    19  		race.ReadPC(unsafe.Pointer(m), callerpc, pc)
    20  	}
    21  
    22  	if m == nil || m.Used() == 0 {
    23  		return unsafe.Pointer(&zeroVal[0])
    24  	}
    25  
    26  	if m.writing != 0 {
    27  		fatal("concurrent map read and map write")
    28  		return nil
    29  	}
    30  
    31  	if m.dirLen == 0 {
    32  		g := groupReference{
    33  			data: m.dirPtr,
    34  		}
    35  		full := g.ctrls().matchFull()
    36  		slotKey := g.key(typ, 0)
    37  		slotSize := typ.SlotSize
    38  		for full != 0 {
    39  			if key == *(*uint32)(slotKey) && full.lowestSet() {
    40  				slotElem := unsafe.Pointer(uintptr(slotKey) + typ.ElemOff)
    41  				return slotElem
    42  			}
    43  			slotKey = unsafe.Pointer(uintptr(slotKey) + slotSize)
    44  			full = full.shiftOutLowest()
    45  		}
    46  		return unsafe.Pointer(&zeroVal[0])
    47  	}
    48  
    49  	k := key
    50  	hash := typ.Hasher(abi.NoEscape(unsafe.Pointer(&k)), m.seed)
    51  
    52  	// Select table.
    53  	idx := m.directoryIndex(hash)
    54  	t := m.directoryAt(idx)
    55  
    56  	// Probe table.
    57  	seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
    58  	for ; ; seq = seq.next() {
    59  		g := t.groups.group(typ, seq.offset)
    60  
    61  		match := g.ctrls().matchH2(h2(hash))
    62  
    63  		for match != 0 {
    64  			i := match.first()
    65  
    66  			slotKey := g.key(typ, i)
    67  			if key == *(*uint32)(slotKey) {
    68  				slotElem := unsafe.Pointer(uintptr(slotKey) + typ.ElemOff)
    69  				return slotElem
    70  			}
    71  			match = match.removeFirst()
    72  		}
    73  
    74  		match = g.ctrls().matchEmpty()
    75  		if match != 0 {
    76  			// Finding an empty slot means we've reached the end of
    77  			// the probe sequence.
    78  			return unsafe.Pointer(&zeroVal[0])
    79  		}
    80  	}
    81  }
    82  
    83  //go:linkname runtime_mapaccess2_fast32 runtime.mapaccess2_fast32
    84  func runtime_mapaccess2_fast32(typ *abi.MapType, m *Map, key uint32) (unsafe.Pointer, bool) {
    85  	if race.Enabled && m != nil {
    86  		callerpc := sys.GetCallerPC()
    87  		pc := abi.FuncPCABIInternal(runtime_mapaccess2_fast32)
    88  		race.ReadPC(unsafe.Pointer(m), callerpc, pc)
    89  	}
    90  
    91  	if m == nil || m.Used() == 0 {
    92  		return unsafe.Pointer(&zeroVal[0]), false
    93  	}
    94  
    95  	if m.writing != 0 {
    96  		fatal("concurrent map read and map write")
    97  		return nil, false
    98  	}
    99  
   100  	if m.dirLen == 0 {
   101  		g := groupReference{
   102  			data: m.dirPtr,
   103  		}
   104  		full := g.ctrls().matchFull()
   105  		slotKey := g.key(typ, 0)
   106  		slotSize := typ.SlotSize
   107  		for full != 0 {
   108  			if key == *(*uint32)(slotKey) && full.lowestSet() {
   109  				slotElem := unsafe.Pointer(uintptr(slotKey) + typ.ElemOff)
   110  				return slotElem, true
   111  			}
   112  			slotKey = unsafe.Pointer(uintptr(slotKey) + slotSize)
   113  			full = full.shiftOutLowest()
   114  		}
   115  		return unsafe.Pointer(&zeroVal[0]), false
   116  	}
   117  
   118  	k := key
   119  	hash := typ.Hasher(abi.NoEscape(unsafe.Pointer(&k)), m.seed)
   120  
   121  	// Select table.
   122  	idx := m.directoryIndex(hash)
   123  	t := m.directoryAt(idx)
   124  
   125  	// Probe table.
   126  	seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
   127  	for ; ; seq = seq.next() {
   128  		g := t.groups.group(typ, seq.offset)
   129  
   130  		match := g.ctrls().matchH2(h2(hash))
   131  
   132  		for match != 0 {
   133  			i := match.first()
   134  
   135  			slotKey := g.key(typ, i)
   136  			if key == *(*uint32)(slotKey) {
   137  				slotElem := unsafe.Pointer(uintptr(slotKey) + typ.ElemOff)
   138  				return slotElem, true
   139  			}
   140  			match = match.removeFirst()
   141  		}
   142  
   143  		match = g.ctrls().matchEmpty()
   144  		if match != 0 {
   145  			// Finding an empty slot means we've reached the end of
   146  			// the probe sequence.
   147  			return unsafe.Pointer(&zeroVal[0]), false
   148  		}
   149  	}
   150  }
   151  
   152  func (m *Map) putSlotSmallFast32(typ *abi.MapType, hash uintptr, key uint32) unsafe.Pointer {
   153  	g := groupReference{
   154  		data: m.dirPtr,
   155  	}
   156  
   157  	match := g.ctrls().matchH2(h2(hash))
   158  
   159  	// Look for an existing slot containing this key.
   160  	for match != 0 {
   161  		i := match.first()
   162  
   163  		slotKey := g.key(typ, i)
   164  		if key == *(*uint32)(slotKey) {
   165  			slotElem := g.elem(typ, i)
   166  			return slotElem
   167  		}
   168  		match = match.removeFirst()
   169  	}
   170  
   171  	// There can't be deleted slots, small maps can't have them
   172  	// (see deleteSmall). Use matchEmptyOrDeleted as it is a bit
   173  	// more efficient than matchEmpty.
   174  	match = g.ctrls().matchEmptyOrDeleted()
   175  	if match == 0 {
   176  		fatal("small map with no empty slot (concurrent map writes?)")
   177  	}
   178  
   179  	i := match.first()
   180  
   181  	slotKey := g.key(typ, i)
   182  	*(*uint32)(slotKey) = key
   183  
   184  	slotElem := g.elem(typ, i)
   185  
   186  	g.ctrls().set(i, ctrl(h2(hash)))
   187  	m.used++
   188  
   189  	return slotElem
   190  }
   191  
   192  //go:linkname runtime_mapassign_fast32 runtime.mapassign_fast32
   193  func runtime_mapassign_fast32(typ *abi.MapType, m *Map, key uint32) unsafe.Pointer {
   194  	if m == nil {
   195  		panic(errNilAssign)
   196  	}
   197  	if race.Enabled {
   198  		callerpc := sys.GetCallerPC()
   199  		pc := abi.FuncPCABIInternal(runtime_mapassign_fast32)
   200  		race.WritePC(unsafe.Pointer(m), callerpc, pc)
   201  	}
   202  	if m.writing != 0 {
   203  		fatal("concurrent map writes")
   204  	}
   205  
   206  	k := key
   207  	hash := typ.Hasher(abi.NoEscape(unsafe.Pointer(&k)), m.seed)
   208  
   209  	// Set writing after calling Hasher, since Hasher may panic, in which
   210  	// case we have not actually done a write.
   211  	m.writing ^= 1 // toggle, see comment on writing
   212  
   213  	if m.dirPtr == nil {
   214  		m.growToSmall(typ)
   215  	}
   216  
   217  	if m.dirLen == 0 {
   218  		if m.used < abi.MapGroupSlots {
   219  			elem := m.putSlotSmallFast32(typ, hash, key)
   220  
   221  			if m.writing == 0 {
   222  				fatal("concurrent map writes")
   223  			}
   224  			m.writing ^= 1
   225  
   226  			return elem
   227  		}
   228  
   229  		// Can't fit another entry, grow to full size map.
   230  		m.growToTable(typ)
   231  	}
   232  
   233  	var slotElem unsafe.Pointer
   234  outer:
   235  	for {
   236  		// Select table.
   237  		idx := m.directoryIndex(hash)
   238  		t := m.directoryAt(idx)
   239  
   240  		seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
   241  
   242  		// As we look for a match, keep track of the first deleted slot
   243  		// we find, which we'll use to insert the new entry if
   244  		// necessary.
   245  		var firstDeletedGroup groupReference
   246  		var firstDeletedSlot uintptr
   247  
   248  		for ; ; seq = seq.next() {
   249  			g := t.groups.group(typ, seq.offset)
   250  			match := g.ctrls().matchH2(h2(hash))
   251  
   252  			// Look for an existing slot containing this key.
   253  			for match != 0 {
   254  				i := match.first()
   255  
   256  				slotKey := g.key(typ, i)
   257  				if key == *(*uint32)(slotKey) {
   258  					slotElem = g.elem(typ, i)
   259  
   260  					t.checkInvariants(typ, m)
   261  					break outer
   262  				}
   263  				match = match.removeFirst()
   264  			}
   265  
   266  			// No existing slot for this key in this group. Is this the end
   267  			// of the probe sequence?
   268  			match = g.ctrls().matchEmptyOrDeleted()
   269  			if match == 0 {
   270  				continue // nothing but filled slots. Keep probing.
   271  			}
   272  			i := match.first()
   273  			if g.ctrls().get(i) == ctrlDeleted {
   274  				// There are some deleted slots. Remember
   275  				// the first one, and keep probing.
   276  				if firstDeletedGroup.data == nil {
   277  					firstDeletedGroup = g
   278  					firstDeletedSlot = i
   279  				}
   280  				continue
   281  			}
   282  			// We've found an empty slot, which means we've reached the end of
   283  			// the probe sequence.
   284  
   285  			// If we found a deleted slot along the way, we can
   286  			// replace it without consuming growthLeft.
   287  			if firstDeletedGroup.data != nil {
   288  				g = firstDeletedGroup
   289  				i = firstDeletedSlot
   290  				t.growthLeft++ // will be decremented below to become a no-op.
   291  			}
   292  
   293  			// If we have no space left, first try to remove some tombstones.
   294  			if t.growthLeft == 0 {
   295  				t.pruneTombstones(typ, m)
   296  			}
   297  
   298  			// If there is room left to grow, just insert the new entry.
   299  			if t.growthLeft > 0 {
   300  				slotKey := g.key(typ, i)
   301  				*(*uint32)(slotKey) = key
   302  
   303  				slotElem = g.elem(typ, i)
   304  
   305  				g.ctrls().set(i, ctrl(h2(hash)))
   306  				t.growthLeft--
   307  				t.used++
   308  				m.used++
   309  
   310  				t.checkInvariants(typ, m)
   311  				break outer
   312  			}
   313  
   314  			t.rehash(typ, m)
   315  			continue outer
   316  		}
   317  	}
   318  
   319  	if m.writing == 0 {
   320  		fatal("concurrent map writes")
   321  	}
   322  	m.writing ^= 1
   323  
   324  	return slotElem
   325  }
   326  
   327  // Key is a 32-bit pointer (only called on 32-bit GOARCH). This source is identical to fast64ptr.
   328  //
   329  // TODO(prattmic): With some compiler refactoring we could avoid duplication of this function.
   330  //
   331  //go:linkname runtime_mapassign_fast32ptr runtime.mapassign_fast32ptr
   332  func runtime_mapassign_fast32ptr(typ *abi.MapType, m *Map, key unsafe.Pointer) unsafe.Pointer {
   333  	if m == nil {
   334  		panic(errNilAssign)
   335  	}
   336  	if race.Enabled {
   337  		callerpc := sys.GetCallerPC()
   338  		pc := abi.FuncPCABIInternal(runtime_mapassign_fast32ptr)
   339  		race.WritePC(unsafe.Pointer(m), callerpc, pc)
   340  	}
   341  	if m.writing != 0 {
   342  		fatal("concurrent map writes")
   343  	}
   344  
   345  	k := key
   346  	hash := typ.Hasher(abi.NoEscape(unsafe.Pointer(&k)), m.seed)
   347  
   348  	// Set writing after calling Hasher, since Hasher may panic, in which
   349  	// case we have not actually done a write.
   350  	m.writing ^= 1 // toggle, see comment on writing
   351  
   352  	if m.dirPtr == nil {
   353  		m.growToSmall(typ)
   354  	}
   355  
   356  	if m.dirLen == 0 {
   357  		if m.used < abi.MapGroupSlots {
   358  			elem := m.putSlotSmallFastPtr(typ, hash, key)
   359  
   360  			if m.writing == 0 {
   361  				fatal("concurrent map writes")
   362  			}
   363  			m.writing ^= 1
   364  
   365  			return elem
   366  		}
   367  
   368  		// Can't fit another entry, grow to full size map.
   369  		m.growToTable(typ)
   370  	}
   371  
   372  	var slotElem unsafe.Pointer
   373  outer:
   374  	for {
   375  		// Select table.
   376  		idx := m.directoryIndex(hash)
   377  		t := m.directoryAt(idx)
   378  
   379  		seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
   380  
   381  		// As we look for a match, keep track of the first deleted slot we
   382  		// find, which we'll use to insert the new entry if necessary.
   383  		var firstDeletedGroup groupReference
   384  		var firstDeletedSlot uintptr
   385  
   386  		for ; ; seq = seq.next() {
   387  			g := t.groups.group(typ, seq.offset)
   388  			match := g.ctrls().matchH2(h2(hash))
   389  
   390  			// Look for an existing slot containing this key.
   391  			for match != 0 {
   392  				i := match.first()
   393  
   394  				slotKey := g.key(typ, i)
   395  				if key == *(*unsafe.Pointer)(slotKey) {
   396  					slotElem = g.elem(typ, i)
   397  
   398  					t.checkInvariants(typ, m)
   399  					break outer
   400  				}
   401  				match = match.removeFirst()
   402  			}
   403  
   404  			// No existing slot for this key in this group. Is this the end
   405  			// of the probe sequence?
   406  			match = g.ctrls().matchEmptyOrDeleted()
   407  			if match == 0 {
   408  				continue // nothing but filled slots. Keep probing.
   409  			}
   410  			i := match.first()
   411  			if g.ctrls().get(i) == ctrlDeleted {
   412  				// There are some deleted slots. Remember
   413  				// the first one, and keep probing.
   414  				if firstDeletedGroup.data == nil {
   415  					firstDeletedGroup = g
   416  					firstDeletedSlot = i
   417  				}
   418  				continue
   419  			}
   420  			// We've found an empty slot, which means we've reached the end of
   421  			// the probe sequence.
   422  
   423  			// If we found a deleted slot along the way, we can
   424  			// replace it without consuming growthLeft.
   425  			if firstDeletedGroup.data != nil {
   426  				g = firstDeletedGroup
   427  				i = firstDeletedSlot
   428  				t.growthLeft++ // will be decremented below to become a no-op.
   429  			}
   430  
   431  			// If there is room left to grow, just insert the new entry.
   432  			if t.growthLeft > 0 {
   433  				slotKey := g.key(typ, i)
   434  				*(*unsafe.Pointer)(slotKey) = key
   435  
   436  				slotElem = g.elem(typ, i)
   437  
   438  				g.ctrls().set(i, ctrl(h2(hash)))
   439  				t.growthLeft--
   440  				t.used++
   441  				m.used++
   442  
   443  				t.checkInvariants(typ, m)
   444  				break outer
   445  			}
   446  
   447  			t.rehash(typ, m)
   448  			continue outer
   449  		}
   450  	}
   451  
   452  	if m.writing == 0 {
   453  		fatal("concurrent map writes")
   454  	}
   455  	m.writing ^= 1
   456  
   457  	return slotElem
   458  }
   459  
   460  //go:linkname runtime_mapdelete_fast32 runtime.mapdelete_fast32
   461  func runtime_mapdelete_fast32(typ *abi.MapType, m *Map, key uint32) {
   462  	if race.Enabled {
   463  		callerpc := sys.GetCallerPC()
   464  		pc := abi.FuncPCABIInternal(runtime_mapdelete_fast32)
   465  		race.WritePC(unsafe.Pointer(m), callerpc, pc)
   466  	}
   467  
   468  	if m == nil || m.Used() == 0 {
   469  		return
   470  	}
   471  
   472  	m.Delete(typ, abi.NoEscape(unsafe.Pointer(&key)))
   473  }
   474
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