diff options
Diffstat (limited to 'src/internal/runtime/maps/map.go')
| -rw-r--r-- | src/internal/runtime/maps/map.go | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/internal/runtime/maps/map.go b/src/internal/runtime/maps/map.go index a4fa07635a..67e4bd6811 100644 --- a/src/internal/runtime/maps/map.go +++ b/src/internal/runtime/maps/map.go @@ -233,11 +233,22 @@ type Map struct { // The number of bits to use in table directory lookups. globalDepth uint8 + // The number of bits to shift out of the hash for directory lookups. + // On 64-bit systems, this is 64 - globalDepth. + globalShift uint8 + // clearSeq is a sequence counter of calls to Clear. It is used to // detect map clears during iteration. clearSeq uint64 } +func depthToShift(depth uint8) uint8 { + if goarch.PtrSize == 4 { + return 32 - depth + } + return 64 - depth +} + func NewMap(mt *abi.SwissMapType, capacity uint64) *Map { if capacity < abi.SwissMapGroupSlots { // TODO: temporary to simplify initial implementation. @@ -259,6 +270,7 @@ func NewMap(mt *abi.SwissMapType, capacity uint64) *Map { //directory: make([]*table, dirSize), globalDepth: globalDepth, + globalShift: depthToShift(globalDepth), } if capacity > abi.SwissMapGroupSlots { @@ -294,12 +306,7 @@ func (m *Map) directoryIndex(hash uintptr) uintptr { if m.dirLen == 1 { return 0 } - // TODO(prattmic): Store the shift as globalShift, as we need that more - // often than globalDepth. - if goarch.PtrSize == 4 { - return hash >> (32 - m.globalDepth) - } - return hash >> (64 - m.globalDepth) + return hash >> (m.globalShift & 63) } func (m *Map) directoryAt(i uintptr) *table { @@ -338,6 +345,7 @@ func (m *Map) installTableSplit(old, left, right *table) { } } m.globalDepth++ + m.globalShift-- //m.directory = newDir m.dirPtr = unsafe.Pointer(&newDir[0]) m.dirLen = len(newDir) |