Robert Dewar <[EMAIL PROTECTED]> writes: > We have not seen ONE imaginary example, let > alone a real example, where the optimziation of loop invariants > (by far the most important optimization in the class we are > discussing) would break existing code.
But didn't this thread get started by a real program that was broken by an optimization of loop invariants? Certainly I got a real bug report of a real problem, which you can see here: http://lists.gnu.org/archive/html/bug-gnulib/2006-12/msg00084.html Here is a bit more discussion: http://gcc.gnu.org/ml/gcc/2006-12/msg00607.html If this doesn't count as "optimization of loop invariants" then what would count? This particular example was just a test program run by "configure", so the penalty for getting it wrong wasn't that severe -- the application compiled its own version of mktime rather than using the system mktime. But I daresay I can find an example of real-world production code that does something similar.
