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Lack of epsilon aware comparison in NETopKV for Fp32 data type #1265

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Lack of epsilon aware comparison in NETopKV for Fp32 data type #1265

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14 changes: 9 additions & 5 deletions src/cpu/kernels/topkv/generic/neon/fp32.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include "src/cpu/kernels/topkv/generic/neon/impl.h"

#include <arm_neon.h>
#include <limits>

namespace arm_compute
{
Expand All @@ -44,21 +45,24 @@ static inline uint32_t reduce_u32x4(uint32x4_t v)
#endif
}

// Explicit specialization for float: may use float32x4_t etc (only in this TU)
// Explicit specialization for float: may use float32x4_t
template <>
uint32_t count_gt_block<float>(const float *ptr, float threshold)
{
using Tag = wrapper::traits::neon_bitvector_tag_t<float, wrapper::traits::BitWidth::W128>;

const auto thr_vec = wrapper::vdup_n(threshold, Tag{});
const auto v = wrapper::vloadq(ptr);
const auto mask = wrapper::vcgt(v, thr_vec); // underlying uint32x4_t
const auto v = wrapper::vloadq(ptr);

// epsilon-aware compare: treat a > b only when (a - b) > epsilon
const float eps_val = std::numeric_limits<float>::epsilon();
const float thr_with_eps = threshold + eps_val;
const auto thr_eps_vec = wrapper::vdup_n(thr_with_eps, Tag{});
const auto mask = wrapper::vcgt(v, thr_eps_vec); // new: v > (threshold + eps)

const uint32x4_t m = mask;
const uint32x4_t b = vshrq_n_u32(m, 31);
return reduce_u32x4(b);
}

} // namespace detail

void topkv_fp32_neon(const ITensor *predictions, const ITensor *targets, ITensor *out, uint32_t k, const Window &win)
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