Optimization attributes const vs. pure

[Johannes Bauer]

On 28.05.2012 16:40, Ángel González wrote:
> On 28/05/12 14:35, Johannes Bauer wrote:
>> So "pure" would be the perfect fit: Global memory is read but not
>> modified (which is also asserted by passing the arguments as "const").
>> Why is gcc then not doing the optimization that I'd want it to perform?
> I have no idea.
> I wondered if it feared fprintf changing global variables on which
> intcmp() depended,
> so I modified it to create the following program, where there is no
> side-effect.
> But it still exhibits the same behavior (intcmp called 100 times if
> pure, 1 if const).

Thank you for trying it out... good to get confirmation that this isn't
just the case with my arch/gcc combination. Would you mind sharing which
platform/gcc version you've tried it out with?

Best regards,
Johannes