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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. struct Point4
  5. {
  6.   Point4()
  7.   {
  8.     data[0] = 0;
  9.     data[1] = 0;
  10.     data[2] = 0;
  11.     data[3] = 0;
  12.   }
  13.  
  14.   float data[4];
  15. };
  16.  
  17. static float SumOfDifferences(const Point4& a, const Point4& b)
  18. {
  19.   // This function only returns the sum of the sum of the components
  20.   float sumValues = 0.0f;
  21.   for(unsigned int i = 0; i < 4; ++i)
  22.   {
  23.     sumValues += a.data[i] + b.data[i];
  24.   }
  25.   return sumValues;
  26. }
  27.  
  28. void Standard()
  29. {
  30.   Point4 a;
  31.   a.data[0] = 1;
  32.   a.data[1] = 2;
  33.   a.data[2] = 3;
  34.   a.data[3] = 4;
  35.  
  36.   Point4 b;
  37.   b.data[0] = 1;
  38.   b.data[1] = 6;
  39.   b.data[2] = 3;
  40.   b.data[3] = 5;
  41.  
  42.   float total = 0.0f;
  43.   for(unsigned int i = 0; i < 1e9; ++i)
  44.   {
  45.     total += SumOfDifferences(a, b);
  46.   }
  47.  
  48.   std::cout << "total: " << total << std::endl;
  49. }
  50.  
  51. void Vectorized()
  52. {
  53.   typedef float v4sf __attribute__ (( vector_size(4*sizeof(float)) ));
  54.  
  55.   v4sf a;
  56.   float* aPointer = (float*)&a;
  57.   aPointer[0] = 1; aPointer[1] = 2; aPointer[2] = 3; aPointer[3] = 4;
  58.  
  59.   v4sf b;
  60.   float* bPointer = (float*)&b;
  61.   bPointer[0] = 1; bPointer[1] = 6; bPointer[2] = 3; bPointer[3] = 5;
  62.  
  63.   v4sf result;
  64.   float* resultPointer = (float*)&result;
  65.  
  66.   for(unsigned int i = 0; i < 1e9; ++i)
  67.   {
  68.     result += a + b; // Vectorized operation
  69.   }
  70.  
  71.   // Sum the components of the result (this is done with the "total += " in the Standard() loop
  72.   float total = 0.0f;
  73.   for(unsigned int component = 0; component < 4; ++component)
  74.   {
  75.     total += resultPointer[component];
  76.   }
  77.   std::cout << "total: " << total << std::endl;
  78. }
  79.  
  80. int main()
  81. {
  82.  
  83.   Standard();
  84.  
  85. //  Vectorized();
  86.  
  87.   return 0;
  88. }
  89.  
Time limit exceeded #stdin #stdout 5s 2676KB
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https://ideone.com/N4rHy
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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