//go:noinline
func d3() {
	x.f = y // ERROR "write barrier prohibited by caller"
	d4()
}

//go:yeswritebarrierrec
func d4() {
	d2()
}

//go:noinline
func systemstack(func()) {}

//go:nowritebarrierrec
func e1() {
	systemstack(e2)
	systemstack(func() {
		x.f = y // ERROR "write barrier prohibited by caller"
	})
}

func e2() {
	x.f = y // ERROR "write barrier prohibited by caller"

// other (nosplit) call before this call (including the call to lock() itself).
//
// However, we switch to the systemstack to record the lock held to ensure that
// we record an accurate lock ordering. e.g., without systemstack, a stack
// split on entry to lock2() would record stack split locks as taken after l,
// even though l is not actually locked yet.
func lockWithRank(l *mutex, rank lockRank) {

	if added {
		// Write the string to the buffer.
		systemstack(func() {
			t.writeString(gen, id, s)
		})
	}
	return id
}

// emit emits a string and creates an ID for it, but doesn't add it to the table. Returns the ID.
func (t *traceStringTable) emit(gen uintptr, s string) uint64 {
	// Grab an ID and write the string to the buffer.
	id := t.tab.stealID()
	systemstack(func() {
		t.writeString(gen, id, s)
	})
	return id

			// systemstack will make the call directly; otherwise, it will switch to
			// g0 to ensure we have enough room to call a libc function.
			//
			// The function literal that we pass to systemstack is not nosplit, but
			// that's ok: we'll be running on a fresh, clean system stack so the stack
			// check will always succeed anyway.
			systemstack(func() {
				ret = callCgoSigaction(uintptr(sig), new, old)

}

//export stackSwitchCallback
func stackSwitchCallback() {
	// We want to trigger a bounds check on the g0 stack. To do this, we
	// need to call a splittable function through systemstack().
	// SetGCPercent contains such a systemstack call.
	gogc := debug.SetGCPercent(100)
	debug.SetGCPercent(gogc)
}

// Regression test for https://go.dev/issue/62440. It should be possible for C

		// an errno value.
		var ret uintptr
		systemstack(func() {
			ret = callCgoMmap(addr, n, prot, flags, fd, off)
		})
		if ret < 4096 {
			return nil, int(ret)
		}
		return unsafe.Pointer(ret), 0
	}
	return sysMmap(addr, n, prot, flags, fd, off)
}

func munmap(addr unsafe.Pointer, n uintptr) {
	if _cgo_munmap != nil {
		systemstack(func() { callCgoMunmap(addr, n) })
		return
	}

func newNowritebarrierrecChecker() *nowritebarrierrecChecker {
	c := &nowritebarrierrecChecker{
		extraCalls: make(map[*ir.Func][]nowritebarrierrecCall),
	}

	// Find all systemstack calls and record their targets. In
	// general, flow analysis can't see into systemstack, but it's
	// important to handle it for this check, so we model it
	// directly. This has to happen before transforming closures in walk since

func mcall(fn func(*g))

// systemstack runs fn on a system stack.
// If systemstack is called from the per-OS-thread (g0) stack, or
// if systemstack is called from the signal handling (gsignal) stack,
// systemstack calls fn directly and returns.
// Otherwise, systemstack is being called from the limited stack
// of an ordinary goroutine. In this case, systemstack switches

		// g0 stack without switching g. We can't safely make
		// a call in this state. (We can't even safely
		// systemstack.)
		return debugCallSystemStack
	}

	// Switch to the system stack to avoid overflowing the user
	// stack.
	var ret string
	systemstack(func() {
		f := findfunc(pc)
		if !f.valid() {
			ret = debugCallUnknownFunc
			return
		}

		name := funcname(f)

	if pin {
		if pinState.isPinned() {
			// multiple pins on same object, set multipin bit
			pinState.setMultiPinned(true)
			// and increase the pin counter
			// TODO(mknyszek): investigate if systemstack is necessary here
			systemstack(func() {
				offset := objIndex * span.elemsize
				span.incPinCounter(offset)
			})
		} else {
			// set pin bit
			pinState.setPinned(true)
		}
	} else {
		// unpin