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

三、OpenMP测试

prime.cpp

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

int main(int argc, char *argv[])
{
    int i;
    int start, end; 
    int    number_of_primes=0; 
    int number_of_41primes=0;
    int number_of_43primes=0;
    double s1,s2;
    start = 1;
    end = 40000000; 

    printf("Range to check for Primes: %d - %d\n\n",start, end);
    s1=clock();
#pragma omp parallel for schedule(dynamic,100) 
        reduction(+:number_of_primes,number_of_41primes,number_of_43primes)

    for (i = start; i <= end; i += 2) {
        int limit, j, prime;
        limit = (int) sqrt((float)i) + 1;
        prime = 1; 
        j = 3;
        
        while (prime && (j <= limit)) {
            if (i%j == 0) prime = 0;
            j += 2;
        }
        if (prime) {
            number_of_primes++;
            if (i%4 == 1) number_of_41primes++;
            if (i%4 == 3) number_of_43primes++;
        }
    }
    s2=clock();
      printf("\n%10e\n",s2-s1);
    printf("\nProgram Done.\n %d primes found\n",number_of_primes);
    printf("\nNumber of 4n+1 primes found: %d\n",number_of_41primes);
    printf("\nNumber of 4n-1 primes found: %d\n",number_of_43primes);

    return 0; 
}

采用优化集合+OpenMP参数

其中，VS2008为/openmp，gcc为-fopenmp，intel compiler为/Qopenmp。

四、Fortran Compiler测试

Fortran编译器和以上的结果类似，除了VS2008（不支持Fortran），

gfortran在普通计算上和intel compiler相差很少，

只是在三角函数运算上落后较多。

linpk标准测试

代码来源：http://www.polyhedron.com/compare0html

矩阵相乘测试(内置函数)

main.f90

program main
implicit none
real(kind = 8) :: A(2000, 2000), B(2000, 2000), C(2000, 2000)
real(kind = 8) :: time_begin, time_end

CALL RANDOM_SEED()
CALL RANDOM_NUMBER(A)
CALL RANDOM_NUMBER(B)

CALL CPU_TIME(time_begin)
C=matmul(A, B)
CALL CPU_TIME(time_end)
WRITE(*,*)"consumed CPU_time(s):", time_end - time_begin

end program

矩阵相乘测试（调用原始blas）

blas代码来源：http://www.netlib.org/lapack/

main.f90

program main
implicit none
real(kind = 8) :: A(2000, 2000), B(2000, 2000), C(2000, 2000)
real(kind = 8) :: time_begin, time_end

CALL RANDOM_SEED()
CALL RANDOM_NUMBER(A)
CALL RANDOM_NUMBER(B)

CALL CPU_TIME(time_begin)
CALL dgemm('N', 'N', 2000, 2000, 2000, 1.0_8, A, 2000, B, 2000, 0.0_8, C, 2000)
CALL CPU_TIME(time_end)
WRITE(*,*)"consumed CPU_time(s):", time_end - time_begin

end program

五、结论

      Intel Compiler在测试中表现良好，尤其对内置函数进行了比较多的优化，VS2008亦表现不错，

gcc除了在三角函数计算里远远落后外，其他的性能表现也还是不错的，考虑到gcc的开源跨平台，因此

占有比Intel Compiler和M$ Compiler更重要的位置。