Re: How expensive are exceptions?

"Sergey P. Derevyago" <non-existent@iobox.com> wrote in
news:466D2397.82B4C072@iobox.com:


And error-eating.

I think his point was that unless you provide another mechanism for
propagating errors, it is not a fair comparison.

As a simple test(probably too simple) I tried the following:
#include <time.h>
#include <stdio.h>
#include <tchar.h>

static int value=0;
int test4(){
    if(value>10000)
        return -1;
    else
        value++;
    return 0;
}
int test3(){
    value++;
    return test4();
}
int test2(){
    value++;
    return test3();
}
int test1(){
    value++;
    return test2();
}
void test4a(){
    if(value>10000)
        throw -1;
    else
        value++;
}
void test3a(){
    value++;
    test4a();
}
void test2a(){
    value++;
    test3a();
}
void test1a(){
    value++;
    test2a();
}

int _tmain(int argc, _TCHAR* argv[])// OK the compiler is MS C++ (2005)
{
    clock_t start=clock();
    for(int i=0;i<1000000;i++)
    {
        for(int k=0;k<1000;k++)
        {
            int result = test1();
            if(result)
            {
                printf("Failed");
                return result;
            }
        }
        value=0;
    }
// try // Alternative using Exceptions
// {
// for(int i=0;i<1000000;i++)
// {
// for(int k=0;k<1000;k++)
// test1a();
// value=0;
// }
// }catch(int x){
// printf("Failed");
// return x;
//
// }
//
    printf("time= %d",clock()-start);
}
// END

Using a common compiler and disabling Exceptions, this produce the
output: time= 6687

Switching the loops run and enabling EH, produced: time= 6140

Enabling exceptions has no effect on the time of the version that does
not use exceptions. But, strangely, disabling EH more than doubles the
time of the version that uses Exceptions.

Also, calling test2A or test2 instead of test1a/test1, which does fewer
increaments, takes longer:6577 and 6859 respectively. And calling test3a
instead takes even longer,7499, while test3 drops the time a bit to 6513.

If the exception/error is not nested(calling test4a and test4)
exceptions take 4999 and error code take 4499. So there are cases even in
this simple test were Error codes are faster.

But there does seem to be some weirdness to my test.

Otis

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