From 172e03a85bcde2b09e2b88c70898b83535e8410e Mon Sep 17 00:00:00 2001
From: zhaojiaying01 <zhaojiaying01@baidu.com>
Date: Fri, 11 Jan 2019 17:32:08 +0800
Subject: [PATCH] optimize norm_op

---
 .../kernel/central-arm-func/norm_arm_func.h   | 49 ++++++++-----------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/src/operators/kernel/central-arm-func/norm_arm_func.h b/src/operators/kernel/central-arm-func/norm_arm_func.h
index e43c034847..6f3cf055f6 100644
--- a/src/operators/kernel/central-arm-func/norm_arm_func.h
+++ b/src/operators/kernel/central-arm-func/norm_arm_func.h
@@ -41,7 +41,6 @@ void NormCompute(const NormParam<CPU> &param) {
   int axis = param.Axis();
 
   const framework::Tensor *input = param.InputX();
-  framework::Tensor square;
   framework::Tensor *norm = param.OutputNorm();
   framework::Tensor *out = param.Out();
 
@@ -52,46 +51,40 @@ void NormCompute(const NormParam<CPU> &param) {
 
   int pre, n, post;
   GetDims(x_dims, axis, &pre, &n, &post);
-  square.Resize(input->dims());
 
   const float *input_ptr = input->data<float>();
-  float *square_ptr = square.mutable_data<float>();
   float *norm_ptr = norm->mutable_data<float>();
   float *out_ptr = out->mutable_data<float>();
 
+  // in_ch = 0; norm = epsilon + x * x
   const float *in_tmp = input_ptr;
-  float *square_tmp = square_ptr;
-  for (int i = 0; i < input->numel(); ++i) {
-    float element = *in_tmp;
-    *square_tmp = element * element;
-    square_tmp++;
+  float *norm_tmp = norm_ptr;
+  for (int i = 0; i < post; ++i) {
+    *norm_tmp = epsilon;
+    *norm_tmp += (*in_tmp) * (*in_tmp);
+    norm_tmp++;
     in_tmp++;
   }
 
-  //  const float *norm_tmp = norm_ptr;
-  //  for (int i = 0; i < norm->numel(); ++i) {
-  //    *norm_tmp = 0;
-  //    norm_tmp++;
-  //  }
-
-  square_tmp = square_ptr;
-  float *norm_tmp = norm_ptr;
-  for (int i = 0; i < pre; ++i) {
-    for (int j = 0; j < post; ++j) {
-      for (int k = 0; k < n; ++k) {
-        if (k == 0) {
-          *norm_tmp = *square_tmp;
-        } else {
-          *norm_tmp += *(square_tmp + k * post);
-        }
-      }
-      float sum = *norm_tmp + epsilon;
-      *norm_tmp = sqrtf(sum);
+  // in_ch >= 1; norm += x * x
+  for (int j = 1; j < n; ++j) {
+    norm_tmp = norm_ptr;
+    for (int i = 0; i < post; ++i) {
+      *norm_tmp += (*in_tmp) * (*in_tmp);
       norm_tmp++;
-      square_tmp++;
+      in_tmp++;
     }
   }
 
+  // norm = sqart(norm)
+  norm_tmp = norm_ptr;
+  for (int i = 0; i < post; ++i) {
+    float sqrt = sqrtf(*norm_tmp);
+    *norm_tmp = sqrt;
+    norm_tmp++;
+  }
+
+  // out = input / norm
   in_tmp = input_ptr;
   norm_tmp = norm_ptr;
   float *out_tmp = out_ptr;
-- 
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