message: [TF2XLA] Replace a call to Pow with an exponent of .5 with Rsqrt
diff: @@ -18,6 +18,7 @@ limitations under the License.
  #include "tensorflow/compiler/tf2xla/xla_helpers.h"
  #include "tensorflow/compiler/tf2xla/xla_op_kernel.h"
  #include "tensorflow/compiler/tf2xla/xla_op_registry.h"
  +#include "tensorflow/compiler/xla/client/lib/math.h"
  #include "tensorflow/compiler/xla/client/xla_builder.h"
  #include "tensorflow/core/util/tensor_format.h"
  @@ -158,9 +159,8 @@ class FusedBatchNormGradOp : public XlaOpKernel {
  offset_backprop = XlaHelpers::ConvertElementType(reduce, scale_dtype);
  // scratch1 = rsqrt(pop_var + epsilon)
  - auto neg_half = XlaHelpers::FloatLiteral(b, scale_dtype, -0.5);
  - auto scratch1 = xla::Pow(
  - xla::Add(var, xla::ConstantR0<float>(b, epsilon_)), neg_half);
  + auto scratch1 =
  + xla::Rsqrt(xla::Add(var, xla::ConstantR0<float>(b, epsilon_)));
  // scratch2 = sum(y_backprop * (x - mean))
  auto mul =
  