...
Run Format

Source file src/runtime/atomic_pointer.go

  // Copyright 2009 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 (
  	"runtime/internal/atomic"
  	"unsafe"
  )
  
  // These functions cannot have go:noescape annotations,
  // because while ptr does not escape, new does.
  // If new is marked as not escaping, the compiler will make incorrect
  // escape analysis decisions about the pointer value being stored.
  // Instead, these are wrappers around the actual atomics (casp1 and so on)
  // that use noescape to convey which arguments do not escape.
  
  // atomicstorep performs *ptr = new atomically and invokes a write barrier.
  //
  //go:nosplit
  func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
  	writebarrierptr_prewrite((*uintptr)(ptr), uintptr(new))
  	atomic.StorepNoWB(noescape(ptr), new)
  }
  
  //go:nosplit
  func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
  	// The write barrier is only necessary if the CAS succeeds,
  	// but since it needs to happen before the write becomes
  	// public, we have to do it conservatively all the time.
  	writebarrierptr_prewrite((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
  	return atomic.Casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new)
  }
  
  // Like above, but implement in terms of sync/atomic's uintptr operations.
  // We cannot just call the runtime routines, because the race detector expects
  // to be able to intercept the sync/atomic forms but not the runtime forms.
  
  //go:linkname sync_atomic_StoreUintptr sync/atomic.StoreUintptr
  func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
  
  //go:linkname sync_atomic_StorePointer sync/atomic.StorePointer
  //go:nosplit
  func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
  	writebarrierptr_prewrite((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
  	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
  }
  
  //go:linkname sync_atomic_SwapUintptr sync/atomic.SwapUintptr
  func sync_atomic_SwapUintptr(ptr *uintptr, new uintptr) uintptr
  
  //go:linkname sync_atomic_SwapPointer sync/atomic.SwapPointer
  //go:nosplit
  func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer {
  	writebarrierptr_prewrite((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
  	old := unsafe.Pointer(sync_atomic_SwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(new)))
  	return old
  }
  
  //go:linkname sync_atomic_CompareAndSwapUintptr sync/atomic.CompareAndSwapUintptr
  func sync_atomic_CompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
  
  //go:linkname sync_atomic_CompareAndSwapPointer sync/atomic.CompareAndSwapPointer
  //go:nosplit
  func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
  	writebarrierptr_prewrite((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
  	return sync_atomic_CompareAndSwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(old), uintptr(new))
  }
  

View as plain text