ncnn/src/layer/arm/relu_arm.cpp

// Tencent is pleased to support the open source community by making ncnn available.
//
// Copyright (C) 2017 THL A29 Limited, a Tencent company. All rights reserved.
//
// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// https://opensource.org/licenses/BSD-3-Clause
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

#include "relu_arm.h"

#if __ARM_NEON
#include <arm_neon.h>
#endif // __ARM_NEON

namespace ncnn {

DEFINE_LAYER_CREATOR(ReLU_arm)

int ReLU_arm::forward_inplace(Mat& bottom_top_blob, const Option& opt) const
{
    int w = bottom_top_blob.w;
    int h = bottom_top_blob.h;
    int channels = bottom_top_blob.c;
    int size = w * h;

    if (slope == 0.f)
    {
        #pragma omp parallel for num_threads(opt.num_threads)
        for (int q=0; q<channels; q++)
        {
            float* ptr = bottom_top_blob.channel(q);

#if __ARM_NEON
            int nn = size >> 2;
            int remain = size - (nn << 2);
#else
            int remain = size;
#endif // __ARM_NEON

#if __ARM_NEON
#if __aarch64__
            float32x4_t _zero = vdupq_n_f32(0.f);
            for (; nn>0; nn--)
            {
                float32x4_t _p = vld1q_f32(ptr);
                _p = vmaxq_f32(_p, _zero);
                vst1q_f32(ptr, _p);

                ptr += 4;
            }
#else
            if (nn > 0)
            {
            asm volatile(
                "veor       q1, q0, q0          \n"
                "0:                             \n"
                "pld        [%1, #128]          \n"
                "vld1.f32   {d0-d1}, [%1 :128]  \n"
                "vmax.f32   q0, q0, q1          \n"
                "subs       %0, #1              \n"
                "vst1.f32   {d0-d1}, [%1 :128]! \n"
                "bne        0b                  \n"
                : "=r"(nn),     // %0
                  "=r"(ptr)     // %1
                : "0"(nn),
                  "1"(ptr)
                : "cc", "memory", "q0", "q1"
            );
            }
#endif // __aarch64__
#endif // __ARM_NEON
            for (; remain>0; remain--)
            {
                *ptr = std::max(*ptr, 0.f);

                ptr++;
            }
        }
    }
    else
    {
        #pragma omp parallel for num_threads(opt.num_threads)
        for (int q=0; q<channels; q++)
        {
            float* ptr = bottom_top_blob.channel(q);

#if __ARM_NEON
            int nn = size >> 2;
            int remain = size - (nn << 2);
#else
            int remain = size;
#endif // __ARM_NEON

#if __ARM_NEON
#if __aarch64__
            float32x4_t _zero = vdupq_n_f32(0.f);
            float32x4_t _slope = vdupq_n_f32(slope);
            for (; nn>0; nn--)
            {
                float32x4_t _p = vld1q_f32(ptr);
                uint32x4_t _lemask = vcleq_f32(_p, _zero);
                float32x4_t _ps = vmulq_f32(_p, _slope);
                _p = vbslq_f32(_lemask, _ps, _p);
                vst1q_f32(ptr, _p);

                ptr += 4;
            }
#else
            if (nn > 0)
            {
            asm volatile(
                "veor       q1, q0, q0          \n"
                "vdup.f32   q2, %4              \n"
                "0:                             \n"
                "pld        [%1, #128]          \n"
                "vld1.f32   {d0-d1}, [%1 :128]  \n"
                "vcle.f32   q3, q0, q1          \n"
                "vmul.f32   q4, q0, q2          \n"
                "vbit.32    q0, q4, q3          \n"
                "subs       %0, #1              \n"
                "vst1.f32   {d0-d1}, [%1 :128]! \n"
                "bne        0b                  \n"
                : "=r"(nn),     // %0
                  "=r"(ptr)     // %1
                : "0"(nn),
                  "1"(ptr),
                  "r"(slope)    // %4
                : "cc", "memory", "q0", "q1", "q2", "q3", "q4"
            );
            }
#endif // __aarch64__
#endif // __ARM_NEON
            for (; remain>0; remain--)
            {
                if (*ptr < 0)
                    *ptr *= slope;

                ptr++;
            }
        }
    }

    return 0;
}

} // namespace ncnn