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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import "unsafe"
// Called from C. Returns the Go type *m.
func gc_m_ptr(ret *interface{}) {
*ret = (*m)(nil)
}
// Called from C. Returns the Go type *g.
func gc_g_ptr(ret *interface{}) {
*ret = (*g)(nil)
}
// Called from C. Returns the Go type *itab.
func gc_itab_ptr(ret *interface{}) {
*ret = (*itab)(nil)
}
func gc_unixnanotime(now *int64) {
sec, nsec := timenow()
*now = sec*1e9 + int64(nsec)
}
func freeOSMemory() {
gogc(2) // force GC and do eager sweep
systemstack(scavenge_m)
}
var poolcleanup func()
func registerPoolCleanup(f func()) {
poolcleanup = f
}
func clearpools() {
// clear sync.Pools
if poolcleanup != nil {
poolcleanup()
}
for _, p := range &allp {
if p == nil {
break
}
// clear tinyalloc pool
if c := p.mcache; c != nil {
c.tiny = nil
c.tinysize = 0
// disconnect cached list before dropping it on the floor,
// so that a dangling ref to one entry does not pin all of them.
var sg, sgnext *sudog
for sg = c.sudogcache; sg != nil; sg = sgnext {
sgnext = sg.next
sg.next = nil
}
c.sudogcache = nil
}
// clear defer pools
for i := range p.deferpool {
// disconnect cached list before dropping it on the floor,
// so that a dangling ref to one entry does not pin all of them.
var d, dlink *_defer
for d = p.deferpool[i]; d != nil; d = dlink {
dlink = d.link
d.link = nil
}
p.deferpool[i] = nil
}
}
}
func bgsweep() {
sweep.g = getg()
getg().issystem = true
for {
for gosweepone() != ^uintptr(0) {
sweep.nbgsweep++
Gosched()
}
lock(&gclock)
if !gosweepdone() {
// This can happen if a GC runs between
// gosweepone returning ^0 above
// and the lock being acquired.
unlock(&gclock)
continue
}
sweep.parked = true
goparkunlock(&gclock, "GC sweep wait")
}
}
const (
_PoisonGC = 0xf969696969696969 & (1<<(8*ptrSize) - 1)
_PoisonStack = 0x6868686868686868 & (1<<(8*ptrSize) - 1)
)
// NOTE: Really dst *unsafe.Pointer, src unsafe.Pointer,
// but if we do that, Go inserts a write barrier on *dst = src.
//go:nosplit
func writebarrierptr(dst *uintptr, src uintptr) {
*dst = src
writebarrierptr_nostore(dst, src)
}
// Like writebarrierptr, but the store has already been applied.
// Do not reapply.
//go:nosplit
func writebarrierptr_nostore(dst *uintptr, src uintptr) {
if getg() == nil { // very low-level startup
return
}
if src != 0 && (src < _PageSize || src == _PoisonGC || src == _PoisonStack) {
systemstack(func() { gothrow("bad pointer in write barrier") })
}
mp := acquirem()
if mp.inwb || mp.dying > 0 {
releasem(mp)
return
}
mp.inwb = true
systemstack(func() {
gcmarkwb_m(dst, src)
})
mp.inwb = false
releasem(mp)
}
//go:nosplit
func writebarrierstring(dst *[2]uintptr, src [2]uintptr) {
writebarrierptr(&dst[0], src[0])
dst[1] = src[1]
}
//go:nosplit
func writebarrierslice(dst *[3]uintptr, src [3]uintptr) {
writebarrierptr(&dst[0], src[0])
dst[1] = src[1]
dst[2] = src[2]
}
//go:nosplit
func writebarrieriface(dst *[2]uintptr, src [2]uintptr) {
writebarrierptr(&dst[0], src[0])
writebarrierptr(&dst[1], src[1])
}
//go:generate go run wbfat_gen.go -- wbfat.go
//
// The above line generates multiword write barriers for
// all the combinations of ptr+scalar up to four words.
// The implementations are written to wbfat.go.
//go:nosplit
func writebarrierfat(typ *_type, dst, src unsafe.Pointer) {
mask := loadPtrMask(typ)
nptr := typ.size / ptrSize
for i := uintptr(0); i < nptr; i += 2 {
bits := mask[i/2]
if (bits>>2)&_BitsMask == _BitsPointer {
writebarrierptr((*uintptr)(dst), *(*uintptr)(src))
} else {
*(*uintptr)(dst) = *(*uintptr)(src)
}
dst = add(dst, ptrSize)
src = add(src, ptrSize)
if i+1 == nptr {
break
}
bits >>= 4
if (bits>>2)&_BitsMask == _BitsPointer {
writebarrierptr((*uintptr)(dst), *(*uintptr)(src))
} else {
*(*uintptr)(dst) = *(*uintptr)(src)
}
dst = add(dst, ptrSize)
src = add(src, ptrSize)
}
}
//go:nosplit
func writebarriercopy(typ *_type, dst, src slice) int {
n := dst.len
if n > src.len {
n = src.len
}
if n == 0 {
return 0
}
dstp := unsafe.Pointer(dst.array)
srcp := unsafe.Pointer(src.array)
if uintptr(srcp) < uintptr(dstp) && uintptr(srcp)+uintptr(n)*typ.size > uintptr(dstp) {
// Overlap with src before dst.
// Copy backward, being careful not to move dstp/srcp
// out of the array they point into.
dstp = add(dstp, uintptr(n-1)*typ.size)
srcp = add(srcp, uintptr(n-1)*typ.size)
i := uint(0)
for {
writebarrierfat(typ, dstp, srcp)
if i++; i >= n {
break
}
dstp = add(dstp, -typ.size)
srcp = add(srcp, -typ.size)
}
} else {
// Copy forward, being careful not to move dstp/srcp
// out of the array they point into.
i := uint(0)
for {
writebarrierfat(typ, dstp, srcp)
if i++; i >= n {
break
}
dstp = add(dstp, typ.size)
srcp = add(srcp, typ.size)
}
}
return int(n)
}
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