hi andrew,
this is C code. I don't use the functions ispow2 etc.
see the code below .
[EMAIL PROTECTED]:/home/junk/prog/tju# gcc bug_short.c -lm -O2
[EMAIL PROTECTED]:/home/junk/prog/tju# ./a.out
2383,1
31727,1
132265613,1
3145439247023686464
[EMAIL PROTECTED]:/home/junk/prog/tju# gcc bug_short.c -lm
[EMAIL PROTECTED]:/home/junk/prog/tju# ./a.out
2383,1
31727,1
132265613,1
10004511787964928
[EMAIL PROTECTED]:/home/junk/prog/tju# cat bug_short.c
#include<stdio.h>
#include<math.h>
typedef unsigned long long ull;
ull
gcd (ull a, ull b)
{
if (b == 0)
return a;
return gcd (b, a % b);
}
int
main ()
{
ull numprod, denprod, gg;
ull arr[] = { 2383, 31727, 132265613 };
ull acnt[] = {1,1,1};
int cntm = sizeof (arr) / sizeof (arr[0]), i;
numprod = denprod = 1;
for (i = 0; i <cntm; i++)
{
ull a = arr[i], b = acnt[i];
printf ("%llu,%llu\n", a, b);
ull num = (ull) (pow ((double) a, (double) b + 1) - 1);
ull den = a - 1;
gg = gcd (num, den);
num /= gg;
den /= gg;
numprod *= num;
denprod *= den;
gg = gcd (numprod, denprod);
numprod /= gg;
denprod /= gg;
}
gg = gcd (numprod, denprod);
numprod /= gg;
denprod /= gg;
printf ("%llu\n", numprod);
return 0;
}
[EMAIL PROTECTED]:/home/junk/prog/tju#
[EMAIL PROTECTED]:~/prog/tju$ gcc bug_short.c -Wall -Wstrict-overflow=2 -lm
[EMAIL PROTECTED]:~/prog/tju$ gcc bug_short.c -Wall -Wstrict-overflow=2 -lm -O2
[EMAIL PROTECTED]:~/prog/tju$ gcc -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
--enable-mpfr --enable-targets=all --enable-checking=release
--build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu
Thread model: posix
gcc version 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
[EMAIL PROTECTED]:~/prog/tju$
Do you want the asm files or other files ? tell me how to give to
you. you want me to do gcc -S and send you the output ?
On Sat, Aug 23, 2008 at 3:48 AM, Andrew Pinski <[EMAIL PROTECTED]> wrote:
> On Fri, Aug 22, 2008 at 3:14 PM, Andrew Pinski <[EMAIL PROTECTED]> wrote:
>> On Fri, Aug 22, 2008 at 2:47 PM, Niklaus <[EMAIL PROTECTED]> wrote:
>>> Hi,
>>>
>>>
>>> When i run with the options g++ prog.c -o prog and run the exectuable
>>> it gives me the correct output
>>> but when i do g++ prog.c -o prog -O2 i get the wrong output
>>>
>
> Note by the way I think your ispow2 is incorrect. It is doing a "a ==
> 1 & a != 0" and not ((a-1)&a) == 0. We do warn about this too:
> t.c:189: warning: suggest parentheses around comparison in operand of &
>
>
> -- Pinski
>
