// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"runtime/internal/atomic"
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"unsafe"
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)
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// These functions cannot have go:noescape annotations,
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// because while ptr does not escape, new does.
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// If new is marked as not escaping, the compiler will make incorrect
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// escape analysis decisions about the pointer value being stored.
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// atomicwb performs a write barrier before an atomic pointer write.
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// The caller should guard the call with "if writeBarrier.enabled".
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//
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//go:nosplit
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func atomicwb(ptr *unsafe.Pointer, new unsafe.Pointer) {
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slot := (*uintptr)(unsafe.Pointer(ptr))
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if !getg().m.p.ptr().wbBuf.putFast(*slot, uintptr(new)) {
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wbBufFlush(slot, uintptr(new))
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}
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}
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// atomicstorep performs *ptr = new atomically and invokes a write barrier.
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//
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//go:nosplit
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func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
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if writeBarrier.enabled {
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atomicwb((*unsafe.Pointer)(ptr), new)
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}
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atomic.StorepNoWB(noescape(ptr), new)
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}
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// Like above, but implement in terms of sync/atomic's uintptr operations.
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// We cannot just call the runtime routines, because the race detector expects
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// to be able to intercept the sync/atomic forms but not the runtime forms.
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//go:linkname sync_atomic_StoreUintptr sync/atomic.StoreUintptr
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func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
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//go:linkname sync_atomic_StorePointer sync/atomic.StorePointer
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//go:nosplit
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func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
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if writeBarrier.enabled {
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atomicwb(ptr, new)
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}
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sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
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}
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//go:linkname sync_atomic_SwapUintptr sync/atomic.SwapUintptr
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func sync_atomic_SwapUintptr(ptr *uintptr, new uintptr) uintptr
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//go:linkname sync_atomic_SwapPointer sync/atomic.SwapPointer
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//go:nosplit
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func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer {
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if writeBarrier.enabled {
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atomicwb(ptr, new)
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}
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old := unsafe.Pointer(sync_atomic_SwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(new)))
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return old
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}
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//go:linkname sync_atomic_CompareAndSwapUintptr sync/atomic.CompareAndSwapUintptr
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func sync_atomic_CompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
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//go:linkname sync_atomic_CompareAndSwapPointer sync/atomic.CompareAndSwapPointer
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//go:nosplit
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func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
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if writeBarrier.enabled {
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atomicwb(ptr, new)
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}
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return sync_atomic_CompareAndSwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(old), uintptr(new))
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}
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