UnsafePointUnsafe = -2 // Unsafe for async preemption

	// UnsafePointRestart1(2) apply on a sequence of instructions, within
	// which if an async preemption happens, we should back off the PC
	// to the start of the sequence when resuming.
	// We need two so we can distinguish the start/end of the sequence
	// in case that two sequences are next to each other.
	UnsafePointRestart1 = -3
	UnsafePointRestart2 = -4

				break // Reached the end, don't bother marking the end
			}
			p = ctxt.EndUnsafePoint(p, newprog, prevPcdata)
			p.Pc = p.Link.Pc
			continue
		}
		if isRestartable(p) {
			val := int64(abi.UnsafePointRestart1)
			if val == prevRestart {
				val = abi.UnsafePointRestart2
			}
			prevRestart = val
			q := Appendp(prev, newprog)
			q.As = APCDATA
			q.From.Type = TYPE_CONST

		// reflect.{makeFuncStub,methodValueCall}.
		//
		// TODO(austin): We should improve this, or opt things
		// in incrementally.
		return false, 0
	}
	switch up {
	case abi.UnsafePointRestart1, abi.UnsafePointRestart2:
		// Restartable instruction sequence. Back off PC to
		// the start PC.
		if startpc == 0 || startpc > pc || pc-startpc > 20 {
			throw("bad restart PC")
		}
		return true, startpc

	fi := findfunc(pc)
	v := pcdatavalue(fi, abi.PCDATA_UnsafePoint, pc)
	switch v {
	case abi.UnsafePointUnsafe:
		return true
	case abi.UnsafePointSafe:
		return false
	case abi.UnsafePointRestart1, abi.UnsafePointRestart2, abi.UnsafePointRestartAtEntry:
		// These are all interruptible, they just encode a nonstandard
		// way of recovering when interrupted.
		return false
	default:
		var buf [20]byte