MOVQ	BX, 32(SP)

	// create istack out of the given (operating system) stack.
	// _cgo_init may update stackguard.
	MOVQ	$runtime·g0(SB), DI
	LEAQ	(-64*1024)(SP), BX
	MOVQ	BX, g_stackguard0(DI)
	MOVQ	BX, g_stackguard1(DI)
	MOVQ	BX, (g_stack+stack_lo)(DI)
	MOVQ	SP, (g_stack+stack_hi)(DI)

	// find out information about the processor we're on
	MOVL	$0, AX
	CPUID
	CMPL	AX, $0
	JE	nocpuinfo

		p = ctxt.EndUnsafePoint(p, newprog, -1)
	}

	// Jump back to here after morestack returns.
	startPred := p

	// MOV	g_stackguard(g), X6
	p = obj.Appendp(p, newprog)
	p.As = AMOV
	p.From.Type = obj.TYPE_MEM
	p.From.Reg = REGG
	p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
	if cursym.CFunc() {
		p.From.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
	}
	p.To.Type = obj.TYPE_REG

// performs a stack check.
//
// In rare cases this may not cause the stack to move, specifically if
// there's a preemption between this call and the next.
func gcTestMoveStackOnNextCall() {
	gp := getg()
	gp.stackguard0 = stackForceMove
}

// gcTestIsReachable performs a GC and returns a bit set where bit i
// is set if ptrs[i] is reachable.
func gcTestIsReachable(ptrs ...unsafe.Pointer) (mask uint64) {