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Re: [lto][RFC] Do not emit hybrid object files
On Sat, Oct 18, 2008 at 8:47 AM, Diego Novillo <dnovillo@google.com> wrote:
> On Sat, Oct 18, 2008 at 08:33, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
>
>> I actually think that the hybrid files should be the default. If you
>> are willing to make invasive changes to your build environment to
>> support two files, then you should be willing to add extra options to
>> support that.
>
> Sorry, I don't follow, what two files are you referring to? Adding
> -flto to your Makefiles hardly qualifies as invasive.
>
> The only scenario where hybrid files are useful is when building a
> library that will be deployed to a third party that may not be using
> the same compiler version that was used to build the library.
>
> In this scenario, I agree that the final user (the user of the
> library) should not be forced to change their build process. They
> would only change it if they are willing to take advantage of the
> additional optimization opportunities.
>
> The only ones who should request generation of hybrid files are the
> creators of the library. And they are already changing their
> Makefiles to generate LTO information, the extra flag won't matter to
> them.
IBM XLC whole program IPA mode defaults to hybrid files. One explicitly
specified -qipa=noobject to avoid emitting standard object files. Hybrid by
default follows the rule of least surprise.
David