On Fri, May 22, 2020 at 11:58:40AM +0200, Jan Beulich wrote: > On 20.05.2020 19:18, Roger Pau Monné wrote: > > I also assume that using no_caller_saved_registers when available or > > else keeping the current behavior is not an acceptable solution? FWIW, > > from a FreeBSD PoV I would be OK with that, as I don't think there are > > any supported targets with clang < 5. > > By "current behavior" do you mean what the patch currently > does (matching my earlier response that I may try going this > route) or the unpatched upstream tree?
Sorry this wasn't clear. By current I meant what's in the upstream tree. IMO having both no_caller_saved_registers, the -ffixed-reg stuff and the current upstream no popcnt implementation is kind of too much divergence? My preference would be to add popcnt support only when no_caller_saved_registers is supported by the compiler, as I think that's the cleanest solution. This is purely a performance optimization, so it doesn't seem that bad to me to request a newish compiler in order to enable it. Roger.
