Compiler optimizations
pmoore
pmoore_member at pathlink.com
Thu May 4 05:29:05 PDT 2006
I think I remember you posting a while ago that you have quite an old machine :)
In article <e3bdub$1dsu$3 at digitaldaemon.com>, Walter Bright says...
>
>On my machine, integer is still faster.
>
>int: 3.7
>double: 4.2
>
>Craig Black wrote:
>> This is probably because you have SSE optimizations disabled.
>> This one works even without SSE. This shows that integer division is
>> slower. Also, if you change the division to multiplication, you will notice
>> that integer multiplication is faster, which is what you would expect.
>>
>> #include <stdio.h>
>> #include <conio.h>
>> #include <time.h>
>>
>> //typedef int divtype;
>> typedef double divtype; // This one is faster
>>
>> int main()
>> {
>> divtype result = 0;
>>
>> clock_t start, finish;
>> double duration;
>>
>> start = clock();
>> divtype max = 100000000;
>> for(divtype div=1; div<max; div++)
>> {
>> divtype i = max - div;
>> result += i / div;
>> }
>> finish = clock();
>> duration = (double)(finish - start) / CLOCKS_PER_SEC;
>>
>> printf("[%f] %2.1f seconds\n",double(result),duration);
>> }
>>
>>
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