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

[Bill Wendling]

FYI:

	http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-October/066389.html

Please read and let me know you comments.

-bw

On Oct 11, 2013, at 2:47 PM, Dmitry Babokin <babokin at gmail.com> wrote:

> Looking forward to these changes! Thanks for working on it.
> 
> 
> On Fri, Oct 11, 2013 at 10:32 PM, Bill Wendling <isanbard at gmail.com> wrote:
> 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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