On 2006-12-31 10:08:32 -0500, Richard Kenner wrote: > > Well, that's not equivalent. For instance, MPFR has many conditions > > that evaluate to TRUE or FALSE on some/many implementations (mainly > > because the type sizes depend on the implementation), even without > > the assumption that an overflow cannot occur. > > Can you give an example of such a condition and show how an > optimization that assumed overflows were undefined could break that > code?
This won't break the code. But I'm saying that if the compiler assumes wrapping, even in some particular cases (e.g. code that *looks like* "overflow check"), it could miss some potential optimizations. That is, it is not possible to avoid breaking overflow checks *and* optimizing everything else. -- Vincent Lefèvre <[EMAIL PROTECTED]> - Web: <http://www.vinc17.org/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/> Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)
