[LLVMdev] Recent changes in -gmlt break sample profiling

[Xinliang David Li]

Sounds fine. My recommendation was based on the assumption that the info
can not be recovered ..

David

On Mon, Oct 27, 2014 at 7:45 AM, Diego Novillo <dnovillo at google.com> wrote:

>
>
> On Fri Oct 24 2014 at 4:06:05 PM Xinliang David Li <xinliangli at gmail.com>
> wrote:
>
>> Diego,
>>
>> I think sampleFDO needs to be designed in a way which can protect itself
>> from future breakage like this. The roots in the unnecessary dependency of
>> sample FDO on gmlt setting. It is totally reasonable to tune debug binary
>> size by changes like this.
>
>
> Sure.
>
>
>> The right way is to fix this is to introduce an internal -g<...> flag for
>> use by sampleFDO -- it will have a fixed definition of what needs to be
>> emitted.
>>
>
> Not so sure. Semantically, -gmlt is exactly what samplefdo needs. Relying
> on the subprogram tag for the function itself was an implementation detail.
>
> Adding yet another debug mode that's very much like -gmlt but not quite is
> going to be confusing for users.
>
> I *believe* we can reproduce the same behaviour by using the source
> location ranges. I'm still not quite sure how, but I've got Eric and David
> within smacking distance, so I'll make myself a nuisance until they give me
> enough hints.
>
>
> Diego.
>
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