[Bug rtl-optimization/66248] subreg truncation not hoisted from loop

[jon at beniston dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66248

--- Comment #4 from Jon Beniston <jon at beniston dot com> ---
Well if it is just truncating the higher bits, why can't it be done at the end
of the loop?

What do you think will be different if it is done at the end of the loop? Can
you think of an example where the value of ret will differ?

The MSBs in an add don't effect the LSBs.