}
	if n&(n-1) != 0 {
		throw("stack size not a power of 2")
	}
	if stackDebug >= 1 {
		print("stackalloc ", n, "\n")
	}

	if debug.efence != 0 || stackFromSystem != 0 {
		n = uint32(alignUp(uintptr(n), physPageSize))
		v := sysAlloc(uintptr(n), &memstats.stacks_sys)
		if v == nil {
			throw("out of memory (stackalloc)")
		}
		return stack{uintptr(v), uintptr(v) + uintptr(n)}
	}

	for n := 1; n <= 1024; n++ {
		if n > 16 && testing.Short() {
			n += n >> 3
		}
		for alignP := 0; alignP < 8; alignP++ {
			for alignQ := 0; alignQ < 8; alignQ++ {
				for alignD := 0; alignD < 8; alignD++ {
					p := make([]byte, alignP+n, alignP+n+10)[alignP:]
					q := make([]byte, alignQ+n, alignQ+n+10)[alignQ:]
					if n&1 != 0 {
						p = p[:n]
					} else {
						q = q[:n]
					}

}

// stdSizes is used if Config.Sizes == nil.
var stdSizes = SizesFor("gc", "amd64")

func (conf *Config) alignof(T Type) int64 {
	f := stdSizes.Alignof
	if conf.Sizes != nil {
		f = conf.Sizes.Alignof
	}
	if a := f(T); a >= 1 {
		return a
	}
	panic("implementation of alignof returned an alignment < 1")
}

func (conf *Config) offsetsof(T *Struct) []int64 {
	var offsets []int64

}

// stdSizes is used if Config.Sizes == nil.
var stdSizes = SizesFor("gc", "amd64")

func (conf *Config) alignof(T Type) int64 {
	f := stdSizes.Alignof
	if conf.Sizes != nil {
		f = conf.Sizes.Alignof
	}
	if a := f(T); a >= 1 {
		return a
	}
	panic("implementation of alignof returned an alignment < 1")
}

func (conf *Config) offsetsof(T *Struct) []int64 {
	var offsets []int64

}

func (s *gcSizes) Alignof(T Type) (result int64) {
	defer func() {
		assert(result >= 1)
	}()

	// For arrays and structs, alignment is defined in terms
	// of alignment of the elements and fields, respectively.
	switch t := under(T).(type) {
	case *Array:
		// spec: "For a variable x of array type: unsafe.Alignof(x)
		// is the same as unsafe.Alignof(x[0]), but at least 1."
		return s.Alignof(t.elem)

}

func (s *gcSizes) Alignof(T Type) (result int64) {
	defer func() {
		assert(result >= 1)
	}()

	// For arrays and structs, alignment is defined in terms
	// of alignment of the elements and fields, respectively.
	switch t := under(T).(type) {
	case *Array:
		// spec: "For a variable x of array type: unsafe.Alignof(x)
		// is the same as unsafe.Alignof(x[0]), but at least 1."
		return s.Alignof(t.elem)

	CMPQ CX, $8
	JL less_than_8

	MOVQ SI, BX
	ANDQ $7, BX
	JZ aligned

	// Process the first few bytes to 8-byte align the input.

	// BX = 8 - BX. We need to process this many bytes to align.
	SUBQ $1, BX
	XORQ $7, BX

	BTQ $0, BX
	JNC align_2

	CRC32B (SI), AX
	DECQ CX
	INCQ SI

align_2:
	BTQ $1, BX
	JNC align_4

	CRC32W (SI), AX

	SUBQ $2, CX
	ADDQ $2, SI

align_4:

	frame.fp = 0

	// On link register architectures, sighandler saves the LR on stack
	// before faking a call.
	if usesLR && injectedCall {
		x := *(*uintptr)(unsafe.Pointer(frame.sp))
		frame.sp += alignUp(sys.MinFrameSize, sys.StackAlign)
		f = findfunc(frame.pc)
		frame.fn = f
		if !f.valid() {
			frame.pc = x
		} else if funcspdelta(f, frame.pc) == 0 {
			frame.lr = x
		}
	}

	if len(p) >= 4*vecMinLen {
		// If not aligned then process the initial unaligned bytes

		if uint64(uintptr(unsafe.Pointer(&p[0])))&uint64(vecAlignMask) != 0 {
			align := uint64(uintptr(unsafe.Pointer(&p[0]))) & uint64(vecAlignMask)
			newlen := vecMinLen - align
			crc = ppc64SlicingUpdateBy8(crc, archCastagnoliTable8, p[:newlen])
			p = p[newlen:]
		}
		// p should be aligned now
		aligned := len(p) & ^vecAlignMask

		panic(fmt.Sprintf("got %d, want %d", got, want))
	}
	if got, want := align(v1), unsafe.Alignof(v1); got != want {
		panic(fmt.Sprintf("got %d, want %d", got, want))
	}

	v2 := "abc"
	if got, want := size(v2), unsafe.Sizeof(v2); got != want {
		panic(fmt.Sprintf("got %d, want %d", got, want))
	}
	if got, want := align(v2), unsafe.Alignof(v2); got != want {
		panic(fmt.Sprintf("got %d, want %d", got, want))
	}