[PATCH] D104556: [InstrProfiling] Make CountersPtr in __profd_ relative

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

Not keeping version compatibility for the raw profile format would actually make my life easier.
But I was CCed on the Linux kernel news https://www.phoronix.com/scan.php?page=news_item&px=Clang-PGO-For-Linux-Next so I paid additional care in this patch.

As we can see the compatibility code is actually minimal: just `if (relativeCounterPtr())` and the associated function.
There comments are longer than the code.

How about we making a one-time exception as a courtesy to the initial check-in of the `CONFIG_PGO_CLANG` feature in the Linux kernel?
There can be a bunch of users testing the PGO functionality.
(Well, you may argue that why I couldn't postpone this patch for some extended time, 1 month? I had this in mind for a while (when I changed XRay and learned a bit about PGO last year I had a plan) but I would probably have postponed this work further if I had not seen that some folks are proposing the MIP profile format.)

The summary can be clarified that this is a one-time exception.
I can set up a calendar reminder for myself to drop the compatibility code in llvm-project after some time (@nickdesaulniers @kees may decide on this).


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D104556/new/

https://reviews.llvm.org/D104556