Apple LLVM 6.0 Warning: profile data may be out of date

I have no clue what this meant, so I googled the problem. I only ended up with some search results such as these:

• Email with Apple employees discussing the name of the compiler flag:
  http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140407/102972.html
• Looks like the actual commit when this warning was added to LLVM:
  http://llvm.org/klaus/clang/commit/859d2b24895e5bfaa52005a48a36236024175bfb/

That last one was good since the commit message actually described the problem:
“a warning that triggers when profile data doesn’t match for the source that’s being compiled with -fprofile-instr-use=“. Now I know this is about PGO, which related to XCode’s Generate Optimization Profile. I had deleted the build folder earlier and this caused the warnings.

Note the importance of always having descriptive commit messages.

How To Fix:
Here, Apple described how to use the Optimization Profile and how to enable it. I don’t want to use the profile I generated and corrupted, so I’m going to properly delete it and disable it. You can always regenerate the profile to fix this problem.

1. Delete the group folder ‘OptimizationProfiles’ in your project
2. Set the ‘Use Optimization Profile’ for the release to ‘No’
3. Build again

This entry was posted in Uncategorized on December 16, 2014.