Add LUT-based leaky relu for QASYMM8 on CPU

* Add LUT generation function for Leaky ReLU.
* Some additional changes in the existing LUT implementation:
  + Bring back the NEON implementation of hard swish for 32-bit
    build. Library size of 64-bit build is not affected.
  + Add some extra #ifdef to remove unnecessary code in 32-bit
    build.

Resolves: COMPMID-5386
Signed-off-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Change-Id: I1ea49611cc922765ee741e31138c888401d33e9b
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7845
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Gunes Bayir <gunes.bayir@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>

1 files changed, 34 insertions, 12 deletions

diff --git a/src/cpu/kernels/activation/generic/neon/qasymm8.cpp b/src/cpu/kernels/activation/generic/neon/qasymm8.cpp
index 29f5e6b376..5095ecf5bd 100644
--- a/src/cpu/kernels/activation/generic/neon/qasymm8.cpp
+++ b/src/cpu/kernels/activation/generic/neon/qasymm8.cpp
@@ -417,9 +417,9 @@ void substitute_bytes_neon(
 #endif // __aarch64__
 } // namespace
 
-void neon_qasymm8_hardswish_lut(const ITensor *src, ITensor *dst, const ActivationLayerInfo &act_info, const Window &window)
+void neon_qasymm8_activation_lut(const ITensor *src, ITensor *dst, const ActivationLayerInfo &act_info, const Window &window)
 {
-    ARM_COMPUTE_ERROR_ON(act_info.activation() != ActivationLayerInfo::ActivationFunction::HARD_SWISH);
+    ARM_COMPUTE_ERROR_ON(!ActivationLayerInfo::is_lut_supported(act_info.activation(), src->info()->data_type()));
 #ifdef __aarch64__
     const int window_step_x  = src->info()->tensor_shape().x();
     Window win_collapsed = window.collapse_if_possible(window, Window::DimZ);
@@ -472,6 +472,13 @@ void neon_qasymm8_activation(const ITensor *src, ITensor *dst, const ActivationL
     const float       a_f32  = act_info.a();
     const float       b_f32  = act_info.b();
 
+#ifndef __aarch64__
+    const auto const_6_f32     = vdupq_n_f32(6.f);
+    const auto const_0_f32     = vdupq_n_f32(0.f);
+    const auto const_3_f32     = vdupq_n_f32(3.f);
+    const auto const_inv_6_f32 = vdupq_n_f32(0.166666667f);
+#endif // __aarch64__
+
     // Initialise scale/offset for re-quantization
     float       s  = qi_in.scale / qi_out.scale;
     float       o  = -qi_in.offset * s + qi_out.offset;
@@ -545,21 +552,28 @@ void neon_qasymm8_activation(const ITensor *src, ITensor *dst, const ActivationL
                 // Re-quantize to new output space
                 tmp = vquantize(tmp_dep, qi_out);
             }
-            else if(act == ActivationLayerInfo::ActivationFunction::LEAKY_RELU)
+#ifndef __aarch64__ // LUT-based implementation is used for aarch64 instead.
+            else if(act == ActivationLayerInfo::ActivationFunction::HARD_SWISH)
             {
+                // De-quantize
                 const auto vin_deq = vdequantize(vin, qi_in);
-
-#ifdef __aarch64__
-                const uint32x4x4_t pos_mask =
+                // Perform activation
+                const float32x4x4_t tmp_dep =
                 {
                     {
-                        wrapper::vcgtz(vin_deq.val[0]),
-                        wrapper::vcgtz(vin_deq.val[1]),
-                        wrapper::vcgtz(vin_deq.val[2]),
-                        wrapper::vcgtz(vin_deq.val[3]),
+                        wrapper::vmul(vin_deq.val[0], wrapper::vmul(const_inv_6_f32, wrapper::vmin(const_6_f32, wrapper::vmax(const_0_f32, wrapper::vadd(vin_deq.val[0], const_3_f32))))),
+                        wrapper::vmul(vin_deq.val[1], wrapper::vmul(const_inv_6_f32, wrapper::vmin(const_6_f32, wrapper::vmax(const_0_f32, wrapper::vadd(vin_deq.val[1], const_3_f32))))),
+                        wrapper::vmul(vin_deq.val[2], wrapper::vmul(const_inv_6_f32, wrapper::vmin(const_6_f32, wrapper::vmax(const_0_f32, wrapper::vadd(vin_deq.val[2], const_3_f32))))),
+                        wrapper::vmul(vin_deq.val[3], wrapper::vmul(const_inv_6_f32, wrapper::vmin(const_6_f32, wrapper::vmax(const_0_f32, wrapper::vadd(vin_deq.val[3], const_3_f32))))),
                     }
                 };
-#else  // __aarch64__
+                // Re-quantize to new output space
+                tmp = vquantize(tmp_dep, qi_out);
+            }
+            else if(act == ActivationLayerInfo::ActivationFunction::LEAKY_RELU)
+            {
+                const auto vin_deq = vdequantize(vin, qi_in);
+
                 const uint32x4x4_t pos_mask =
                 {
                     {
@@ -569,7 +583,6 @@ void neon_qasymm8_activation(const ITensor *src, ITensor *dst, const ActivationL
                         wrapper::vcgt(vin_deq.val[3], vconst_0_f32),
                     }
                 };
-#endif // __aarch64__
 
                 const float32x4x4_t tmp_dep =
                 {
@@ -583,6 +596,7 @@ void neon_qasymm8_activation(const ITensor *src, ITensor *dst, const ActivationL
 
                 tmp = vquantize(tmp_dep, qi_out);
             }
+#endif // __aarch64__
             else
             {
                 ARM_COMPUTE_ERROR("Unsupported activation function");
@@ -622,12 +636,20 @@ void neon_qasymm8_activation(const ITensor *src, ITensor *dst, const ActivationL
                 tmp_f       = a_f32 * std::tanh(b_f32 * tmp_f);
                 tmp         = quantize_qasymm8(tmp_f, qi_out);
             }
+#ifndef __aarch64__ // LUT-based implementation is used for aarch64 instead.
+            else if(act == ActivationLayerInfo::ActivationFunction::HARD_SWISH)
+            {
+                float tmp_f = dequantize_qasymm8(in, qi_in);
+                tmp_f       = tmp_f * ((std::min(std::max((tmp_f + 3), 0.0f), 6.0f)) * 0.166666667f);
+                tmp         = quantize_qasymm8(tmp_f, qi_out);
+            }
             else if(act == ActivationLayerInfo::ActivationFunction::LEAKY_RELU)
             {
                 float tmp_f = dequantize_qasymm8(in, qi_in);
                 tmp_f       = tmp_f > 0 ? tmp_f : tmp_f * a_f32;
                 tmp         = quantize_qasymm8(tmp_f, qi_out);
             }
+#endif // __aarch64__
             else
             {
                 ARM_COMPUTE_ERROR("Unsupported activation function");