[llvm] [InstrProfiling] Don't attempt to create duplicate data variables. (PR #71998)

[Alan Phipps via llvm-commits]

evodius96 wrote:

> Can you quickly comment on the impact of that bug? Does it mean the compiler crashes, miscompiles, or loses coverage information?

The missing data variable may result in lost coverage information for functions fully inlined into other instrumented functions.  If inlining happens after the profiling pass, there’s no problem, but that’s obviously a faulty assumption.  The solution is to move where the data variable is created and also ensure that MC/DC parameter information is processed first.  I think the fix is also straightforward, and I should have the PR tomorrow.

https://github.com/llvm/llvm-project/pull/71998