[cfe-dev] Proposal: add instrumentation for PGO and code coverage

[Katzfey, Eric]

> -----Original Message-----
> From: cfe-dev-bounces at cs.uiuc.edu [mailto:cfe-dev-bounces at cs.uiuc.edu]
> On Behalf Of Diego Novillo
> Sent: Saturday, September 07, 2013 6:55 AM
> To: Bob Wilson
> Cc: clang-dev Developers
> Subject: Re: [cfe-dev] Proposal: add instrumentation for PGO and code
> coverage
> 
> 
> In terms of the metadata representation, what are your thoughts on the on-
> disk format to use? Since we want to support multiple external profile
> sources, I would like to define a canonical on-disk representation that every
> profiling source should convert to.
> 
> This way, the profile loader in the compiler needs to handle that single file
> format.
> 
[Eric] Yes, I am thinking in terms of embedded targets where instrumentation cannot work. I would like to be able to take trace data generated by the program running on target and then pull out the relevant profile data on branch counts to feed to PGO. How do I create the profile format such that the branch counts taken from the code addresses of the executable match up to the branches being optimized by the compiler?

Also, to the point of only having one data file per executable, it seems like it would be better to associate a data file per source file. That way I can more easily store my profile data along with my source file and it will get used individually when that source file gets pulled into different builds.

Thanks!