}

    // To improve accuracy on platforms with less-precise log implementations,
    // compute log(lanczos_gamma_plus_one_half) at compile time and use log1p on
    // the device.
    // log(t) = log(kLanczosGamma + 0.5 + z)
    //        = log(kLanczosGamma + 0.5) + log1p(z / (kLanczosGamma + 0.5))
    Value t = rewriter.create<AddV2Op>(loc, lanczos_gamma_plus_one_half, z);
    Value z_div_lanczos_gamma_plus_one_half =

            "Atan", "Atanh", "Ceil", "Cos", "Cosh", "Sin", "Exp", "Expm1",
            "Floor", "IsFinite", "IsInf", "IsNan", "Inv", "Reciprocal", "Log",
            "Log1p", "Invert", "LogicalNot", "Ndtri", "Neg", "Rint", "Round",
            "Rsqrt", "Sigmoid", "Sign", "Sinh", "Softplus", "Softsign", "Sqrt",
            "Square", "Tan", "Tanh", "Real", "Imag", "Erf", "Erfc", "Erfinv",

	return int64(ntz64(^x))
}

// logX returns logarithm of n base 2.
// n must be a positive power of 2 (isPowerOfTwoX returns true).
func log8(n int8) int64 {
	return int64(bits.Len8(uint8(n))) - 1
}
func log16(n int16) int64 {
	return int64(bits.Len16(uint16(n))) - 1
}
func log32(n int32) int64 {
	return int64(bits.Len32(uint32(n))) - 1
}
func log64(n int64) int64 {
	return int64(bits.Len64(uint64(n))) - 1
}