编译器优化性能初步比较

OS：Windows XP 32 bit

CPU：Intel Mobile Core 2 Duo T6600

一、混合四则运算

main.c

#include <stdio.h>
#include <time.h>
int main()
{
      int i,j,a=1,b=1;
      float c=1.0,d=1.0;
      double e=1.0,f=1.0;
      double start, finish, duration;
      start=clock();
      for (i = 0; i < 1000; i++)
      {
            for (j = 0; j < 1000000; j++)
            {
                  a = a + 50;
                  b = a - 100;
                  a = b * 20;
                  c = a + 300.89;
                  d = c - 600.89;
                  c = d * 90.89;
                  d = c / 55.89;
                  e = c * 90.89;
                  f = e / 55.89;
            }
      }
      finish=clock();
      duration=finish-start;
      printf("%f,%f\n",e,f);
      printf("%10e",duration);
      return 0;
}

耗时比较（单位：秒）

优化集合为

二、三角函数

main.c(来源于Intel官方)

#include <stdio.h>
#include <stdlib.h> 
#include <time.h> 
#include <math.h>

#define INTEG_FUNC(x)  abs(sin(x))

int main(void)
{
   unsigned int i, j, N;
   double step, x_i, sum;
   double start, finish, duration;
   double interval_begin = 0.0;
   double interval_end = 2.0 * 3.141592653589793238;

   start = clock();

   printf("     \n");
   printf("    Number of    | Computed Integral | \n");
   printf(" Interior Points |                   | \n");
   for (j=2;j<27;j++)
   {
    printf("------------------------------------- \n");

     N =  1 << j;
     step = (interval_end - interval_begin) / N;
     sum = INTEG_FUNC(interval_begin) * step / 2.0;

     for (i=1;i<N;i++)
     {
        x_i = i * step;
        sum += INTEG_FUNC(x_i) * step;
     }

     sum += INTEG_FUNC(interval_end) * step / 2.0;

     printf(" %10d      |  %14e   | \n", N, sum);
   }
   finish = clock();
   duration = (finish - start);
   printf("     \n");
   printf("   Application Clocks   = %10e  \n", duration);
   printf("     \n");
}

耗时比较（单位：秒）

优化集合同上