message: Small simplification in IrArray::Index
diff: @@ -130,8 +130,7 @@ bool IrArray::Index::LinearValidOnShape(const Shape& a) const {
  IrArray::Index IrArray::Index::SourceIndexOfReshape(
  const Shape& output_shape, const Shape& input_shape,
  llvm::IRBuilder<>* builder) const {
  - const auto& target_index = *this;
  - CHECK_EQ(target_index.size(), output_shape.rank());
  + CHECK_EQ(multidim_.size(), output_shape.rank());
  std::vector<std::pair<int64, int64>> common_factors =
  CommonFactors(AsInt64Slice(input_shape.dimensions()),
  AsInt64Slice(output_shape.dimensions()));
  @@ -240,11 +239,7 @@ IrArray::Index IrArray::Index::SourceIndexOfBitcast(
  scale *= shape.dimensions(dimension);
  }
  - // Now delinearize it for the input of the bitcast.
  - std::vector<llvm::Value*> multi_index(operand_shape.dimensions_size());
  - Delinearize(&multi_index, linear_index, operand_shape, builder);
  -
  - return Index(multi_index, linear_index, operand_shape, index_type_);
  + return Index(linear_index, operand_shape, builder);
  }
  IrArray::Index IrArray::Index::SourceIndexOfBroadcast(
  