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Re: Can LTO minor version be updated in backward compatible way ?
On 7/17/19 8:10 PM, Jeff Law wrote:
> On 7/17/19 11:29 AM, Andi Kleen wrote:
>> Romain Geissler <romain.geissler@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.
Why and what is ironic about it?
> Red Hat's toolchain team is
> planning to propose switching to LTO by default for Fedora 32 and were
> working through various details yesterday.
Great!
> Our proposal will almost
> certainly include stripping out the LTO bits from .o's and any static
> libraries.
Yes, we do it as well for now.
Martin
>
> Jeff
>