kernels/portable/cpu/op_minimum.cpp

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include <executorch/kernels/portable/cpu/scalar_utils.h>
#include <executorch/kernels/portable/cpu/util/broadcast_util.h>
#include <executorch/kernels/portable/cpu/util/math_util.h>
#include <executorch/runtime/kernel/kernel_includes.h>

namespace torch {
namespace executor {
namespace native {
namespace {

template <
    bool can_cast,
    typename CTYPE_A,
    typename CTYPE_B,
    typename CTYPE_IN,
    typename CTYPE_OUT>
struct MinimumInner;

template <
    typename CTYPE_A,
    typename CTYPE_B,
    typename CTYPE_IN,
    typename CTYPE_OUT>
struct MinimumInner<true, CTYPE_A, CTYPE_B, CTYPE_IN, CTYPE_OUT> {
  static void run(const Tensor& a, const Tensor& b, Tensor& out) {
    apply_binary_elementwise_fn<CTYPE_A, CTYPE_B, CTYPE_OUT>(
        // NOLINTNEXTLINE(facebook-hte-ConstantArgumentPassByValue)
        [](const CTYPE_A val_a, const CTYPE_B val_b) {
          CTYPE_IN a_casted = static_cast<CTYPE_IN>(val_a);
          CTYPE_IN b_casted = static_cast<CTYPE_IN>(val_b);
          CTYPE_IN value = utils::min_override(a_casted, b_casted);

          return static_cast<CTYPE_OUT>(value);
        },
        a,
        b,
        out);
  }
};

struct ReportCanCastBug {
  static void run(const Tensor&, const Tensor&, Tensor&) {
    ET_DCHECK_MSG(false, "BUG: canCast should have been checked above");
  }
};

template <
    typename CTYPE_A,
    typename CTYPE_B,
    typename CTYPE_IN,
    typename CTYPE_OUT>
struct MinimumInner<false, CTYPE_A, CTYPE_B, CTYPE_IN, CTYPE_OUT>
    : public ReportCanCastBug {};

} // namespace

Tensor& minimum_out(
    RuntimeContext& ctx,
    const Tensor& a,
    const Tensor& b,
    Tensor& out) {
  (void)ctx;

  ET_KERNEL_CHECK(
      ctx,
      resize_to_broadcast_target_size(a, b, out) == Error::Ok,
      InvalidArgument,
      out);

  ScalarType a_type = a.scalar_type();
  ScalarType b_type = b.scalar_type();
  ScalarType common_type = promoteTypes(a_type, b_type, /*half_to_float*/ true);
  ScalarType out_type = out.scalar_type();

  ET_KERNEL_CHECK(ctx, canCast(common_type, out_type), InvalidArgument, out);

  ET_SWITCH_REALHB_TYPES(a_type, ctx, "minimum.out", CTYPE_A, [&]() {
    ET_SWITCH_REALHB_TYPES(b_type, ctx, "minimum.out", CTYPE_B, [&]() {
      using CTYPE_IN = typename torch::executor::
          promote_types<CTYPE_A, CTYPE_B, /*half_to_float*/ true>::type;
      ET_DCHECK(CppTypeToScalarType<CTYPE_IN>::value == common_type);
      ET_SWITCH_REALHB_TYPES(out_type, ctx, "minimum.out", CTYPE_OUT, [&]() {
        MinimumInner<
            can_cast<CTYPE_IN, CTYPE_OUT>::value,
            CTYPE_A,
            CTYPE_B,
            CTYPE_IN,
            CTYPE_OUT>::run(a, b, out);
      });
    });
  });

  return out;
}

} // namespace native
} // namespace executor
} // namespace torch