* corresponds to the least significant nonzero byte in lw ^ rw, since lw and rw are
             * little-endian. Long.numberOfTrailingZeros(diff) tells us the least significant
             * nonzero bit, and zeroing out the first three bits of L.nTZ gives us the shift to get
             * that least significant nonzero byte.
             */
            int n = Long.numberOfTrailingZeros(lw ^ rw) & ~0x7;

             * corresponds to the least significant nonzero byte in lw ^ rw, since lw and rw are
             * little-endian. Long.numberOfTrailingZeros(diff) tells us the least significant
             * nonzero bit, and zeroing out the first three bits of L.nTZ gives us the shift to get
             * that least significant nonzero byte.
             */
            int n = Long.numberOfTrailingZeros(lw ^ rw) & ~0x7;

				clobbers: buildReg("R20 R21 R1"),
			},
			typ:            "Mem",
			faultOnNilArg0: true,
			faultOnNilArg1: true,
		},

		// large or unaligned zeroing
		// arg0 = address of memory to zero (in R20, changed as side effect)
		// arg1 = address of the last element to zero
		// arg2 = mem
		// auxint = alignment
		// returns mem
		//	MOVx	R0, (R20)

	b := make([]int, 5)
	c := make([]int, 5)
	for i := -1; i <= 0; i-- {
		b[i] = i
		n++
		if n > 10 {
			break
		}
	}
	useSlice(a)
	useSlice(c)
}

// Check that prove is zeroing these right shifts of positive ints by bit-width - 1.
// e.g (Rsh64x64 <t> n (Const64 <typ.UInt64> [63])) && ft.isNonNegative(n) -> 0
func sh64(n int64) int64 {
	if n < 0 {
		return n
	}

			},
			typ:            "Mem",
			faultOnNilArg0: true,
			faultOnNilArg1: true,
		},

		// Generic moves and zeros

		// general unaligned zeroing
		// arg0 = address of memory to zero (in X5, changed as side effect)
		// arg1 = address of the last element to zero (inclusive)
		// arg2 = mem
		// auxint = element size
		// returns mem
		//	mov	ZERO, (X5)

// strip off fractional word zeroing
(Zero [s] ptr mem) && s%16 != 0 && s%16 <= 8 && s > 16 =>
	(Zero [8]
		(OffPtr <ptr.Type> ptr [s-8])
		(Zero [s-s%16] ptr mem))
(Zero [s] ptr mem) && s%16 != 0 && s%16 > 8 && s > 16 =>
	(Zero [16]
		(OffPtr <ptr.Type> ptr [s-16])
		(Zero [s-s%16] ptr mem))

// medium zeroing uses a duff device

			unlock(&mheap_.lock)
		})
		return false
	}

	if spc.sizeclass() != 0 {
		// Handle spans for small objects.
		if nfreed > 0 {
			// Only mark the span as needing zeroing if we've freed any
			// objects, because a fresh span that had been allocated into,
			// wasn't totally filled, but then swept, still has all of its
			// free slots zeroed.
			s.needzero = 1

	// ppc64le:`MOVW\s`
	// ppc64:`MOVWBR`
	b[(idx<<2)+3], b[(idx<<2)+2], b[(idx<<2)+1], b[(idx<<2)+0] = byte(val>>24), byte(val>>16), byte(val>>8), byte(val)
}

// ------------- //
//    Zeroing    //
// ------------- //

// Check that zero stores are combined into larger stores

func zero_byte_2(b1, b2 []byte) {
	// bounds checks to guarantee safety of writes below
	_, _ = b1[1], b2[1]

			(MOVOstoreconst [makeValAndOff(0,16)] destptr
				(MOVOstoreconst [makeValAndOff(0,0)] destptr mem))))

// Medium zeroing uses a duff device.
(Zero [s] destptr mem)
	&& s > 64 && s <= 1024 && s%16 == 0 && !config.noDuffDevice =>
	(DUFFZERO [s] destptr mem)

// Large zeroing uses REP STOSQ.
(Zero [s] destptr mem)
	&& (s > 1024 || (config.noDuffDevice && s > 64 || !config.useSSE && s > 32))
	&& s%8 == 0 =>

		// large or unaligned zeroing
		// arg0 = address of memory to zero (in R3, changed as side effect)
		// returns mem
		//
		// a loop is generated when there is more than one iteration
		// needed to clear 4 doublewords
		//