T12545 allocates nearly 5% more when passed ` -v`, leading to increase and decrease in different jobs of same patch

!5624 (closed) is an example where the vanilla deb9 job shows a 4% increase in the ghc/alloc metric of T12545, whereas the i386-deb9 job (and a few others) decrease the same metric by 3.2%.

This comment thread also shows that as soon as one passes -v to find out which pass increases, allocations rise from 1.7GB to 1.8GB. That's about 5%! Also, the patched version increases a lot less (from 1.76 to 1.78) and actually all passes improve slightly.