[llvm-dev] (RFC) Encoding code duplication factor in discriminator

[Dehao Chen via llvm-dev]

Thanks all for the comments.

I've moved forward with "adding a new -f flag" solution in
https://reviews.llvm.org/D25435

Please comment on that patch about flag naming etc.

Thanks,
Dehao

On Wed, Nov 23, 2016 at 1:39 PM, Eric Christopher <echristo at gmail.com>
wrote:

> (Agreed for the record).
>
> -eric
>
> On Wed, Nov 23, 2016 at 1:21 PM David Blaikie via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> yep, +1, seems like a -f flag to me. (you'd want to be able to combine it
>> with any other level of debugging - no need to have to choose between
>> profiling or debugging)
>>
>> On Tue, Nov 22, 2016 at 3:46 PM Greg Bedwell <gregbedwell at gmail.com>
>> wrote:
>>
>> For our users we fully expect their profile/debug builds to be the same
>> thing (that is, almost all debugging is on fully optimized code, where
>> fully optimized also means part of an iterative profiling workflow).
>> Having extra debug information that only benefits the profiling part seems
>> reasonable.  What would be unacceptable is if we ever had to ask our users
>> to make a trade off between debug info that was best for profiling at the
>> expense of debugging quality or vice versa.  The "-femit-debug-for-profiling"
>> flag seems to fit this model of it being more a strict superset rather than
>> a tuning option more clearly.
>>
>>
>> -Greg
>>
>>
>> On 22 November 2016 at 23:16, Dehao Chen via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> -gprofile should have:
>>
>> 1. emit linkage name in all subprograms
>> 2. emit discriminator with dup-factor copy-factor encoded
>> 3. use-unknown-locations=true
>>
>> Here comes the problem: is it an intermediate -g mode between -g1 and
>> -g2? If yes, this means that -g2 will also need to include all the 3 items
>> above. If not, then it should not be called -gprofile, but rather a flag
>> like -femit-debug-for-profiling", so that we can use it with "-g2
>> -femit-debug-for-profiling", or "-gmlt -femit-debug-for-profiling".
>>
>>
>> Yep, sounds about right (should have a -fno- option too, should it imply
>> -g of some kind if you specify it alone? I'd prefer to avoid implication
>> (implies flags get weird/hard to handle imho) if possible. Just have a
>> reasonable recommendation of -gmlt -fprof-debug or whatever we call it (I'm
>> bad with names))
>>
>> - Dave
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>
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