[LLVMdev] "target-features" and "target-cpu" attributes

[Bill Wendling]

Hi Dmitry,

I can try my best, but it would be a bit tricky to get it all finished by then...

-bw

On Oct 11, 2013, at 4:10 AM, Dmitry Babokin <babokin at gmail.com> wrote:

> Bill,
> 
> Are there any chances that you complete it before 3.4 is branched?
> 
> 
> On Thu, Oct 10, 2013 at 10:16 PM, Bill Wendling <isanbard at gmail.com> wrote:
> On Oct 10, 2013, at 4:22 AM, Dmitry Babokin <babokin at gmail.com> wrote:
> 
> > Bill,
> >
> > Thanks for answering. To make sure that we are on the same page, let's agree on definitions :) Here, by fat binaries I mean the binary, where some functions are compiled for one flavor of x86, while others are compiled for another flavor of x86. I care about the usage model, which is important for LTO - a dispatch function (compiled for the least common denominator) + plus set of specialized functions for sse4, avx ,avx2 and etc., which are called by dispatch function depending on runtime cpu id check.
> >
> Okay. The terminology was a bit overloaded. :-)
> 
> > lipo may help achieving this on Darwin, but it's not exactly what I need. I need a solution suitable for LTO. Actually lipo may work for me as a workaround, but I need cross platform solution.
> >
> > The current solution doesn't really address this (on x86 at least), as sub-target is not recreated if feature string doesn't match the sub-target. Instead it tries to satisfy feature string requirements using existing sub-target and this leads to the fails, that were noticed by Ben. Please correct me if my understanding is wrong.
> >
> > So do I understand you correctly, that your new solution supposed to solve this problem?
> >
> That's correct. It still needs to be implemented (of course), but that's the eventual goal.
> 
> -bw
> 
> 

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