On 7/17/19 11:29 AM, Andi Kleen wrote: > Romain Geissler <romain.geiss...@amadeus.com> writes: >> >> I have no idea of the LTO format and if indeed it can easily be updated >> in a backward compatible way. But I would say it would be nice if it >> could, and would allow adoption for projects spread on many teams >> depending on each others and unable to re-build everything at each >> toolchain update. > > Right now any change to an compiler option breaks the LTO format > in subtle ways. In fact even the minor changes that are currently > done are not frequent enough to catch all such cases. > > So it's unlikely to really work. Right and stable LTO bytecode really isn't on the radar at this time.
IMHO it's more important right now to start pushing LTO into the mainstream for the binaries shipped by the vendors (and stripping the LTO bits out of any static libraries/.o's shipped by the vendors). SuSE's announcement today is quite ironic. Red Hat's toolchain team is planning to propose switching to LTO by default for Fedora 32 and were working through various details yesterday. Our proposal will almost certainly include stripping out the LTO bits from .o's and any static libraries. Jeff
