func (m *Matcher) stack(w Writer) bool {
	const maxStack = 16
	var stk [maxStack]uintptr
	n := runtime.Callers(2, stk[:])
	// caller #2 is not for printing; need it to normalize PCs if ASLR.
	if n <= 1 {
		return false
	}

	base := stk[0]
	// normalize PCs
	for i := range stk[:n] {
		stk[i] -= base
	}

	h := Hash(stk[:n])
	if m.ShouldPrint(h) {
		var d *dedup
		for {

		ppid := data[2] >> 1
		if hasP := (data[2] & 0b1) != 0; !hasP {
			ppid = ^uint64(0)
		}
		goid := data[3]
		mpid := data[4]
		stk := data[5:recordLen]

		// Overflow records always have their headers contain
		// all zeroes.
		isOverflowRecord := len(stk) == 1 && data[2] == 0 && data[3] == 0 && data[4] == 0

		// Move the data iterator forward.
		data = data[recordLen:]

		// Only racing against reader, not other writers.
		count, time := b.takeOverflow()
		if count > 0 {
			var stk [1]uintptr
			stk[0] = uintptr(count)
			b.write(nil, int64(time), nil, stk[:])
		}
	} else if hasOverflow || !b.canWriteRecord(len(stk)) {
		// Pending overflow without room to write overflow and new records
		// or no overflow but also no room for new record.
		b.incrementOverflow(now)
		b.wakeupExtra()

	}
	if p.write != nil {
		panic("pprof: Add called on built-in Profile " + p.name)
	}

	stk := make([]uintptr, 32)
	n := runtime.Callers(skip+1, stk[:])
	stk = stk[:n]
	if len(stk) == 0 {
		// The value for skip is too large, and there's no stack trace to record.
		stk = []uintptr{abi.FuncPCABIInternal(lostProfileEvent)}
	}

	p.mu.Lock()
	defer p.mu.Unlock()
	if p.m[value] != nil {

	if !isMatchErr && (nogoErr != nil || isScanErr) {
		stk.Push(path)
		defer stk.Pop()
	}

	p.Error = &PackageError{
		ImportStack: stk.Copy(),
		Pos:         pos,
		Err:         err,
	}
	p.Incomplete = true

	if path != stk.Top() {
		p.Error.setPos(importPos)
	}
}

// Resolve returns the resolved version of imports,

func runtime_expandFinalInlineFrame(stk []uintptr) []uintptr {
	// TODO: It would be more efficient to report only physical PCs to pprof and
	// just expand the whole stack.
	if len(stk) == 0 {
		return stk
	}
	pc := stk[len(stk)-1]
	tracepc := pc - 1

	f := findfunc(tracepc)
	if !f.valid() {
		// Not a Go function.
		return stk
	}

	u, uf := newInlineUnwinder(f, tracepc)

		if b.typ == typ && b.hash == h && b.size == size && eqslice(b.stk(), stk) {
			return b
		}
	}

	if !alloc {
		return nil
	}

	lock(&profInsertLock)
	// check again under the insertion lock
	for b := (*bucket)(bh[i].Load()); b != nil; b = b.next {
		if b.typ == typ && b.hash == h && b.size == size && eqslice(b.stk(), stk) {
			unlock(&profInsertLock)
			return b
		}
	}

		})
	}
}

// May run with m.p==nil, so write barriers are not allowed.
//
//go:nowritebarrier
func newosproc(mp *m) {
	stk := unsafe.Pointer(mp.g0.stack.hi)
	if false {
		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " id=", mp.id, " ostk=", &mp, "\n")
	}

	var uc ucontextt
	getcontext(unsafe.Pointer(&uc))

	// _UC_SIGMASK does not seem to work here.

}

// stackfree frees an n byte stack allocation at stk.
//
// stackfree must run on the system stack because it uses per-P
// resources and must not split the stack.
//
//go:systemstack
func stackfree(stk stack) {
	gp := getg()
	v := unsafe.Pointer(stk.lo)
	n := stk.hi - stk.lo
	if n&(n-1) != 0 {
		throw("stack not a power of 2")
	}
	if stk.lo+n < stk.hi {
		throw("bad stack size")
	}

func (d *Decoder) autoClose(t Token) (Token, bool) {
	if d.stk == nil || d.stk.kind != stkStart {
		return nil, false
	}
	for _, s := range d.AutoClose {
		if strings.EqualFold(s, d.stk.name.Local) {
			// This one should be auto closed if t doesn't close it.
			et, ok := t.(EndElement)
			if !ok || !strings.EqualFold(et.Name.Local, d.stk.name.Local) {
				return EndElement{d.stk.name}, true
			}
			break
		}
	}