[llvm] [BOLT] Refactor tracking internals of BinaryFunction. NFCI (PR #167074)

[Maksim Panchenko via llvm-commits]

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@@ -1520,6 +1520,17 @@ void BinaryContext::foldFunction(BinaryFunction &ChildBF,
   }
   ChildBF.getSymbols().clear();
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maksfb wrote:

Thanks for the review.

The `clear()` call will remove symbol references from the list, but the symbols themselves will stay intact. All `MCSymbol`s are allocated in the `MCContext` and are managed by an instance of that class. I.e. even if `Rel->Symbol` was in the `getSymbols()` list (it shouldn't), it would still be valid to reference it.

https://github.com/llvm/llvm-project/pull/167074