[Bug tree-optimization/79460] gcc fails to optimise out a trivial additive loop for seemingly arbitrary numbers of iterations

[drraph at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79460

--- Comment #1 from Raphael C <drraph at gmail dot com> ---
After some experimentation (also carried out by Hagen von Eitzen), it seems
that any limit of at least 72 which is also a multiple of 4 causes the same
optimisation problem. That is the loop is *not* optimised out in these cases.  

Perhaps this is an example of one optimisation (SIMD vectorisation) conflicting
with another?