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, 35 insertions, 3 deletions

diff --git a/arm_compute/core/Types.h b/arm_compute/core/Types.h
index 4524976d6b..94fe1a07f4 100644
--- a/arm_compute/core/Types.h
+++ b/arm_compute/core/Types.h
@@ -1680,6 +1680,7 @@ public:
         return _enabled;
     }
 
+#ifdef __aarch64__
     const LookupTable256 &lut() const
     {
         return _lut;
@@ -1687,7 +1688,27 @@ public:
 
     void init_lut(const UniformQuantizationInfo &qi_in, const UniformQuantizationInfo &qi_out)
     {
-        qasymm8_hard_swish_populate_table(_lut, qi_in, qi_out);
+        if(_act == ActivationFunction::HARD_SWISH)
+        {
+            qasymm8_hard_swish_populate_table(_lut, qi_in, qi_out);
+        }
+        else if(_act == ActivationFunction::LEAKY_RELU)
+        {
+            qasymm8_leaky_relu_populate_table(_lut, qi_in, qi_out, _a);
+        }
+    }
+#endif // __aarch64__
+
+    static inline bool is_lut_supported(ActivationFunction act_func, DataType data_type)
+    {
+#ifdef __aarch64__
+        auto supported = (data_type == DataType::QASYMM8 && (act_func == ActivationFunction::HARD_SWISH || act_func == ActivationFunction::LEAKY_RELU));
+        return supported;
+#else  // __aarch64__
+        ARM_COMPUTE_UNUSED(act_func);
+        ARM_COMPUTE_UNUSED(data_type);
+        return false;
+#endif // __aarch64__
     }
 
 private:
@@ -1695,15 +1716,26 @@ private:
     float              _a       = {};
     float              _b       = {};
     bool               _enabled = { false };
-    LookupTable256     _lut     = {};
 
-    inline void qasymm8_hard_swish_populate_table(LookupTable256 &lut, const UniformQuantizationInfo &qi_in, const UniformQuantizationInfo &qi_out)
+#ifdef __aarch64__
+    LookupTable256 _lut = {};
+
+    static inline void qasymm8_hard_swish_populate_table(LookupTable256 &lut, const UniformQuantizationInfo &qi_in, const UniformQuantizationInfo &qi_out)
     {
         for(size_t i = 0; i < lut.size(); ++i)
         {
             lut[i] = qasymm8_hard_swish(i, qi_in, qi_out);
         }
     }
+
+    static inline void qasymm8_leaky_relu_populate_table(LookupTable256 &lut, const UniformQuantizationInfo &qi_in, const UniformQuantizationInfo &qi_out, float alpha)
+    {
+        for(size_t i = 0; i < lut.size(); ++i)
+        {
+            lut[i] = qasymm8_leaky_relu(i, qi_in, qi_out, alpha);
+        }
+    }
+#endif // __aarch64__
 };
 
 /** Fully connected layer info */