// It's safe to call Pin on non-Go pointers, in which case Pin will do nothing.
func (p *Pinner) Pin(pointer any) {
	if p.pinner == nil {
		// Check the pinner cache first.
		mp := acquirem()
		if pp := mp.p.ptr(); pp != nil {
			p.pinner = pp.pinnerCache
			pp.pinnerCache = nil
		}
		releasem(mp)

		if p.pinner == nil {
			// Didn't get anything from the pinner cache.
			p.pinner = new(pinner)

	}
}

// acquireLockRankAndM acquires a rank which is not associated with a mutex
// lock. To maintain the invariant that an M with m.locks==0 does not hold any
// lock-like resources, it also acquires the M.
//
// This function may be called in nosplit context and thus must be nosplit.
//
//go:nosplit
func acquireLockRankAndM(rank lockRank) {
	acquirem()

	gp := getg()

	// be inlinable. If they have no callers in their packages, they
	// might not actually be inlined anywhere.
	want := map[string][]string{
		"runtime": {
			"add",
			"acquirem",
			"add1",
			"addb",
			"adjustpanics",
			"adjustpointer",
			"alignDown",
			"alignUp",
			"bucketMask",
			"bucketShift",
			"chanbuf",
			"evacuated",
			"fastlog2",
			"float64bits",

	// events to indicate whether a P exists, rather than just making its
	// existence implicit.
	mp = acquirem()
	for _, pp := range allp[len(allp):cap(allp)] {
		pp.trace.readyNextGen(traceNextGen(gen))
	}
	releasem(mp)

	if stopTrace {
		// Acquire the shutdown sema to begin the shutdown process.
		semacquire(&traceShutdownSema)

		// Finish off CPU profile reading.

//go:nosplit
func canpanic() bool {
	gp := getg()
	mp := acquirem()

	// Is it okay for gp to panic instead of crashing the program?
	// Yes, as long as it is running Go code, not runtime code,
	// and not stuck in a system call.
	if gp != mp.curg {
		releasem(mp)
		return false
	}
	// N.B. mp.locks != 1 instead of 0 to account for acquirem.

// the garbage collector from transitioning to mark termination since
// gcWork may locally hold GC work buffers. This can be done by
// disabling preemption (systemstack or acquirem).
type gcWork struct {
	// wbuf1 and wbuf2 are the primary and secondary work buffers.
	//
	// This can be thought of as a stack of both work buffers'
	// pointers concatenated. When we pop the last pointer, we

	// and again to make sure we finish the sweep phase.
	runtime.GC()
	runtime.GC()

	// Disable preemption so we stay on one P's tiny allocator and
	// nothing else allocates from it.
	runtime.Acquirem()

	// Make 1-byte allocations until we get a fresh tiny slot.
	aligned := false
	for i := 0; i < 16; i++ {
		x := runtime.Escape(new(byte))
		if uintptr(unsafe.Pointer(x))&0xf == 0xf {
			aligned = true

		if cap >= 0 {
			return newarray(typ, cap)
		}
		return newobject(typ)
	}

	// Prevent preemption as we set up the space for a new object.
	//
	// Act like we're allocating.
	mp := acquirem()
	if mp.mallocing != 0 {
		throw("malloc deadlock")
	}
	if mp.gsignal == getg() {
		throw("malloc during signal")
	}
	mp.mallocing = 1

	var ptr unsafe.Pointer
	if !typ.Pointers() {

	//    modified state.
	//
	// We achieve these through different mechanisms:
	//
	// 1. Addition of new Ms to allm in allocm happens before clone of its
	//    OS thread later in newm.
	// 2. newm does acquirem to avoid being preempted, ensuring that new Ms
	//    created in allocm will eventually reach OS thread clone later in
	//    newm.
	// 3. We take allocmLock for write here to prevent allocation of new Ms

func (l *gcCPULimiterState) startGCTransition(enableGC bool, now int64) {
	if !l.tryLock() {
		// This must happen during a STW, so we can't fail to acquire the lock.
		// If we did, something went wrong. Throw.
		throw("failed to acquire lock to start a GC transition")
	}
	if l.gcEnabled == enableGC {
		throw("transitioning GC to the same state as before?")
	}