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Diffstat (limited to 'src/runtime')
-rw-r--r--src/runtime/hashmap.go65
-rw-r--r--src/runtime/hashmap_fast.go33
-rw-r--r--src/runtime/map_test.go16
3 files changed, 54 insertions, 60 deletions
diff --git a/src/runtime/hashmap.go b/src/runtime/hashmap.go
index 4f5d03d983..ff59faab5d 100644
--- a/src/runtime/hashmap.go
+++ b/src/runtime/hashmap.go
@@ -236,9 +236,6 @@ func makemap(t *maptype, hint int64, h *hmap, bucket unsafe.Pointer) *hmap {
throw("need padding in bucket (value)")
}
- // make sure zeroptr is large enough
- mapzero(t.elem)
-
// find size parameter which will hold the requested # of elements
B := uint8(0)
for ; hint > bucketCnt && float32(hint) > loadFactor*float32(uintptr(1)<<B); B++ {
@@ -283,7 +280,7 @@ func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
msanread(key, t.key.size)
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -321,7 +318,7 @@ func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
}
}
@@ -337,7 +334,7 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
msanread(key, t.key.size)
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -375,7 +372,7 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
}
}
@@ -426,6 +423,22 @@ func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe
}
}
+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
+}
+
func mapassign1(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
if h == nil {
panic(plainError("assignment to entry in nil map"))
@@ -1044,39 +1057,5 @@ func reflect_ismapkey(t *_type) bool {
return ismapkey(t)
}
-var zerolock mutex
-
-const initialZeroSize = 1024
-
-var zeroinitial [initialZeroSize]byte
-
-// All accesses to zeroptr and zerosize must be atomic so that they
-// can be accessed without locks in the common case.
-var zeroptr unsafe.Pointer = unsafe.Pointer(&zeroinitial)
-var zerosize uintptr = initialZeroSize
-
-// mapzero ensures that zeroptr points to a buffer large enough to
-// serve as the zero value for t.
-func mapzero(t *_type) {
- // Is the type small enough for existing buffer?
- cursize := uintptr(atomic.Loadp(unsafe.Pointer(&zerosize)))
- if t.size <= cursize {
- return
- }
-
- // Allocate a new buffer.
- lock(&zerolock)
- cursize = uintptr(atomic.Loadp(unsafe.Pointer(&zerosize)))
- if cursize < t.size {
- for cursize < t.size {
- cursize *= 2
- if cursize == 0 {
- // need >2GB zero on 32-bit machine
- throw("map element too large")
- }
- }
- atomic.StorepNoWB(unsafe.Pointer(&zeroptr), persistentalloc(cursize, 64, &memstats.other_sys))
- atomic.StorepNoWB(unsafe.Pointer(&zerosize), unsafe.Pointer(zerosize))
- }
- unlock(&zerolock)
-}
+const maxZero = 1024 // must match value in ../cmd/compile/internal/gc/walk.go
+var zeroVal [maxZero]byte
diff --git a/src/runtime/hashmap_fast.go b/src/runtime/hashmap_fast.go
index 6a5484edee..8f9bb5a6fc 100644
--- a/src/runtime/hashmap_fast.go
+++ b/src/runtime/hashmap_fast.go
@@ -5,7 +5,6 @@
package runtime
import (
- "runtime/internal/atomic"
"runtime/internal/sys"
"unsafe"
)
@@ -16,7 +15,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast32))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -50,7 +49,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
}
}
@@ -61,7 +60,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast32))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -95,7 +94,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
}
}
@@ -106,7 +105,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_fast64))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -140,7 +139,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
}
}
@@ -151,7 +150,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_fast64))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -185,7 +184,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
}
}
@@ -196,7 +195,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_faststr))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -220,7 +219,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.valuesize))
}
}
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
// long key, try not to do more comparisons than necessary
keymaybe := uintptr(bucketCnt)
@@ -258,7 +257,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.valuesize))
}
}
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
dohash:
hash := t.key.alg.hash(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@@ -290,7 +289,7 @@ dohash:
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr))
+ return unsafe.Pointer(&zeroVal[0])
}
}
}
@@ -301,7 +300,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_faststr))
}
if h == nil || h.count == 0 {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
throw("concurrent map read and map write")
@@ -325,7 +324,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.valuesize)), true
}
}
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
// long key, try not to do more comparisons than necessary
keymaybe := uintptr(bucketCnt)
@@ -361,7 +360,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.valuesize)), true
}
}
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
dohash:
hash := t.key.alg.hash(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@@ -393,7 +392,7 @@ dohash:
}
b = b.overflow(t)
if b == nil {
- return atomic.Loadp(unsafe.Pointer(&zeroptr)), false
+ return unsafe.Pointer(&zeroVal[0]), false
}
}
}
diff --git a/src/runtime/map_test.go b/src/runtime/map_test.go
index 9d2894cb6f..496f8e8868 100644
--- a/src/runtime/map_test.go
+++ b/src/runtime/map_test.go
@@ -317,6 +317,22 @@ func TestBigItems(t *testing.T) {
}
}
+func TestMapHugeZero(t *testing.T) {
+ type T [4000]byte
+ m := map[int]T{}
+ x := m[0]
+ if x != (T{}) {
+ t.Errorf("map value not zero")
+ }
+ y, ok := m[0]
+ if ok {
+ t.Errorf("map value should be missing")
+ }
+ if y != (T{}) {
+ t.Errorf("map value not zero")
+ }
+}
+
type empty struct {
}
generated by cgit v1.3 (git 2.53.0) at 2026-04-16 05:19:54 +0000