(Lsh64x(64|32|16|8) x y) && shiftIsBounded(v) => (SHLQ x y)
(Lsh32x(64|32|16|8) x y) && shiftIsBounded(v) => (SHLL x y)
(Lsh16x(64|32|16|8) x y) && shiftIsBounded(v) => (SHLL x y)
(Lsh8x(64|32|16|8)  x y) && shiftIsBounded(v) => (SHLL x y)

(Rsh64Ux(64|32|16|8) <t> x y) && !shiftIsBounded(v) => (ANDQ (SHRQ <t> x y) (SBBQcarrymask <t> (CMP(Q|L|W|B)const y [64])))

(Lsh64x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLD x y)
(Lsh32x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLW x y)
(Lsh16x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLD x y)
(Lsh8x(64|32|16|8)   x y) && shiftIsBounded(v) => (SLD x y)
(Rsh64Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRD x y)
(Rsh32Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRW x y)

(Lsh64x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLD x y)
(Lsh32x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLW x y)
(Lsh16x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLW x y)
(Lsh8x(64|32|16|8)   x y) && shiftIsBounded(v) => (SLW x y)
(Rsh64Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRD x y)
(Rsh32Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRW x y)

// b2i32 translates a boolean value to 0 or 1.
func b2i32(b bool) int32 {
	if b {
		return 1
	}
	return 0
}

// shiftIsBounded reports whether (left/right) shift Value v is known to be bounded.
// A shift is bounded if it is shifting by less than the width of the shifted value.
func shiftIsBounded(v *Value) bool {
	return v.AuxInt != 0
}

// canonLessThan returns whether x is "ordered" less than y, for purposes of normalizing

			lim, ok := ft.limits[by.ID]
			if !ok {
				break
			}
			bits := 8 * v.Args[0].Type.Size()
			if lim.umax < uint64(bits) || (lim.max < bits && ft.isNonNegative(by)) {
				v.AuxInt = 1 // see shiftIsBounded
				if b.Func.pass.debug > 0 {
					b.Func.Warnl(v.Pos, "Proved %v bounded", v.Op)
				}
			}
		case OpDiv16, OpDiv32, OpDiv64, OpMod16, OpMod32, OpMod64: