message: [XLA:GPU] Pick the right shape for emitting memsets for elements with size 2
  Otherwise this could would be wrong for multi-output fusions of fp16 or bf16.
  We currently never use those for reduce-fusions on GPU.
diff: @@ -2710,8 +2710,9 @@ StatusOr<std::unique_ptr<Thunk>> IrEmitterUnnested::BuildInitializerThunk(
  // If the literal is 8 or 16 bits wide, we can emit a 32-bit memset by
  // repeating the literal 4 or 2 times, so long as the destination buffer is
  // an even multiple of 32 bits long.
  + const Shape& output_shape = ShapeUtil::GetSubshape(hlo->shape(), index);
  if ((num_bytes == 1 || num_bytes == 2) &&
  - ShapeUtil::ByteSizeOf(hlo->shape()) % 4 == 0) {
  + ShapeUtil::ByteSizeOf(output_shape) % 4 == 0) {
  uint16 pattern16;
  if (num_bytes == 1) {
  uint8 b = literal_bytes.front();
  