[Bug c/30475] assert(int+100 > int) optimized away

["pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #42 from pinskia at gcc dot gnu dot org  2007-01-22 02:27 -------
(In reply to comment #41)
> So I tested some C++ vector code using at, in a desperate attempt to find ANY
> case where this so called "optimization" actually produces faster code.

Try looking at real code instead of benchmarks :).  I bet the reason why ICC
beats GCC is not because GCC cannot do a good job but ICC's standard template
library is implemented slightly different.


>  $ gcc -O3 -o vector2 vector2.C
>  $ ./vector2
>  69859 cycles
>  $ gcc -O3 -o vector2 vector2.C -fwrapv
>  $ ./vector2
>  69606 cycles

I bet this is all to do with cache and not really anything do with the
optimization.

>Why don't you get over the fact that this was a really bad decision,
> undo it, and we will all live happily ever after.

Only a few people think it is a bad decision.  Anyways nothing said in this bug
will change anything, you should do what Tom Tromey  said in comment #40 and
what I mentioned in comment #22, and write to the gcc@gcc.gnu.org mailing list
after reading all previous decussion on this matter.  Since it sounds like you
only care about the security code which was incorrectly written.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30475