We should renable the this flag at least at -O3 and above. See PR 15023 for why it was disabled, every problem except for the compiler time issue was a latent target bug.
There are patches missing from 4.0 to fix some cases where regrename could produce wrong code. Besides, enabling passes on a release branch sounds like an awfully bad idea. Setting 4.1 as the target milestone is more reasonable than 4.0.2 IMVHO.
I concur, done. W.
This has been fixed for -funroll-loops so closing as fixed as it is fixed as much as I filed it for.