[LLVMdev] Indirect call site profiling

[Philip Reames]

On 11/03/2014 09:21 AM, Diego Novillo wrote:
>
> On 11/03/14 12:12, betulb at codeaurora.org wrote:
>>
>>> I'll be interested in seeing your work. I'm interested in techniques
>>> for guarded devirtualization, but the profiling infrastructure 
>>> should be
>>> fairly common.  If we could arrange the instrumentation in such a 
>>> way to
>>> enable both use cases, we could share infrastructure.
>> Thanks, we've recently posted an RFC on the design. The design is quite
>> straightforward and simple but the gains will be seen when the data is
>> used in optimizations.
>
> A note on the profile. The sample pgo profiler tracks indirect 
> function calls via sampling at the call sites. Currently this data is 
> not being used in optimizations, but it's captured in the sample 
> profiles (lib/Transforms/Scalar/SampleProfile.cpp).
We also have a custom profiling mechanism which collects similar data.  
It seems like moving forward with a common metadata format to exploit 
this would be interesting.

(I'm moving the rest of my comments to the proposal thread; I wanted 
this one in context.)

Philip