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runtime: revert "move zeroVal to internal/abi" 

This reverts CL 581395, commit 2f5b420fb5.
It breaks a linkname from github.com/ugorji/go/codec.
For #67401.

A followup CL will document this dependence.

Change-Id: I66d6c39c03e769ab829ca4c3f4f61277b93380d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/587216
TryBot-Bypass: Russ Cox <rsc@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Russ Cox 2024-05-21 23:04:21 -04:00 committed by Gopher Robot
parent 2b8d9e3997
commit 4c589d93ad
8 changed files with 38 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
src/internal/abi/runtime.go
View File

@ -4,8 +4,5 @@
package abi
// ZeroValSize is the size in bytes of [ZeroVal].
// ZeroValSize is the size in bytes of runtime.zeroVal.
const ZeroValSize = 1024
// ZeroVal is a region containing all zero bytes.
var ZeroVal [ZeroValSize]byte

11
src/reflect/value.go
View File

@ -1591,7 +1591,7 @@ func (v Value) IsZero() bool {
// v.ptr doesn't escape, as Equal functions are compiler generated
// and never escape. The escape analysis doesn't know, as it is a
// function pointer call.
return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&abi.ZeroVal[0]))
return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&zeroVal[0]))
}
if typ.TFlag&abi.TFlagRegularMemory != 0 {
// For some types where the zero value is a value where all bits of this type are 0
@ -1617,7 +1617,7 @@ func (v Value) IsZero() bool {
// If the type is comparable, then compare directly with zero.
if typ.Equal != nil && typ.Size() <= abi.ZeroValSize {
// See noescape justification above.
return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&abi.ZeroVal[0]))
return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&zeroVal[0]))
}
if typ.TFlag&abi.TFlagRegularMemory != 0 {
// For some types where the zero value is a value where all bits of this type are 0
@ -2312,7 +2312,7 @@ func (v Value) Set(x Value) {
}
x = x.assignTo("reflect.Set", v.typ(), target)
if x.flag&flagIndir != 0 {
if x.ptr == unsafe.Pointer(&abi.ZeroVal[0]) {
if x.ptr == unsafe.Pointer(&zeroVal[0]) {
typedmemclr(v.typ(), v.ptr)
} else {
typedmemmove(v.typ(), v.ptr, x.ptr)
@ -3280,7 +3280,7 @@ func Zero(typ Type) Value {
if t.IfaceIndir() {
var p unsafe.Pointer
if t.Size() <= abi.ZeroValSize {
p = unsafe.Pointer(&abi.ZeroVal[0])
p = unsafe.Pointer(&zeroVal[0])
} else {
p = unsafe_New(t)
}
@ -3289,6 +3289,9 @@ func Zero(typ Type) Value {
return Value{t, nil, fl}
}
//go:linkname zeroVal runtime.zeroVal
var zeroVal [abi.ZeroValSize]byte
// New returns a Value representing a pointer to a new zero value
// for the specified type. That is, the returned Value's Type is [PointerTo](typ).
func New(typ Type) Value {

4
src/runtime/iface.go
View File

@ -391,7 +391,7 @@ func convT64(val uint64) (x unsafe.Pointer) {
func convTstring(val string) (x unsafe.Pointer) {
if val == "" {
x = unsafe.Pointer(&abi.ZeroVal[0])
x = unsafe.Pointer(&zeroVal[0])
} else {
x = mallocgc(unsafe.Sizeof(val), stringType, true)
*(*string)(x) = val
@ -402,7 +402,7 @@ func convTstring(val string) (x unsafe.Pointer) {
func convTslice(val []byte) (x unsafe.Pointer) {
// Note: this must work for any element type, not just byte.
if (*slice)(unsafe.Pointer(&val)).array == nil {
x = unsafe.Pointer(&abi.ZeroVal[0])
x = unsafe.Pointer(&zeroVal[0])
} else {
x = mallocgc(unsafe.Sizeof(val), sliceType, true)
*(*[]byte)(x) = val

12
src/runtime/map.go
View File

@ -402,7 +402,7 @@ func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
if err := mapKeyError(t, key); err != nil {
panic(err) // see issue 23734
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -443,7 +443,7 @@ bucketloop:
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
@ -463,7 +463,7 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
if err := mapKeyError(t, key); err != nil {
panic(err) // see issue 23734
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -504,7 +504,7 @@ bucketloop:
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
// returns both key and elem. Used by map iterator.
@ -553,7 +553,7 @@ bucketloop:
func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointer {
e := mapaccess1(t, h, key)
if e == unsafe.Pointer(&abi.ZeroVal[0]) {
if e == unsafe.Pointer(&zeroVal[0]) {
return zero
}
return e
@ -561,7 +561,7 @@ func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointe
func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Pointer, bool) {
e := mapaccess1(t, h, key)
if e == unsafe.Pointer(&abi.ZeroVal[0]) {
if e == unsafe.Pointer(&zeroVal[0]) {
return zero, false
}
return e, true

8
src/runtime/map_fast32.go
View File

@ -16,7 +16,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast32))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -47,7 +47,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
@ -56,7 +56,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast32))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -87,7 +87,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
func mapassign_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {

8
src/runtime/map_fast64.go
View File

@ -16,7 +16,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast64))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -47,7 +47,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
@ -56,7 +56,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast64))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -87,7 +87,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
func mapassign_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {

16
src/runtime/map_faststr.go
View File

@ -16,7 +16,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_faststr))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -39,7 +39,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+i*uintptr(t.ValueSize))
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
// long key, try not to do more comparisons than necessary
keymaybe := uintptr(abi.MapBucketCount)
@ -74,7 +74,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+keymaybe*uintptr(t.ValueSize))
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
dohash:
hash := t.Hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@ -102,7 +102,7 @@ dohash:
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0])
return unsafe.Pointer(&zeroVal[0])
}
func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
@ -111,7 +111,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_faststr))
}
if h == nil || h.count == 0 {
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
if h.flags&hashWriting != 0 {
fatal("concurrent map read and map write")
@ -134,7 +134,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+i*uintptr(t.ValueSize)), true
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
// long key, try not to do more comparisons than necessary
keymaybe := uintptr(abi.MapBucketCount)
@ -169,7 +169,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+keymaybe*uintptr(t.ValueSize)), true
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
dohash:
hash := t.Hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@ -197,7 +197,7 @@ dohash:
}
}
}
return unsafe.Pointer(&abi.ZeroVal[0]), false
return unsafe.Pointer(&zeroVal[0]), false
}
func mapassign_faststr(t *maptype, h *hmap, s string) unsafe.Pointer {

6
src/runtime/runtime.go
View File

@ -5,6 +5,7 @@
package runtime
import (
"internal/abi"
"internal/runtime/atomic"
"unsafe"
)
@ -301,3 +302,8 @@ var auxv []uintptr
//
//go:linkname getAuxv
func getAuxv() []uintptr { return auxv }
// zeroVal is used by reflect via linkname.
//
//go:linkname zeroVal
var zeroVal [abi.ZeroValSize]byte