[llvm] [BOLT] Add support for safe-icf (PR #116275)

[Maksim Panchenko via llvm-commits]

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@@ -428,6 +428,9 @@ class BinaryFunction {
   /// Function order for streaming into the destination binary.
   uint32_t Index{-1U};
 
+  /// Function is referenced by a non-control flow instruction.
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maksfb wrote:

Add a comment that at the moment this flag is only valid under ICF. When we'll need it for other purposes, we should refactor the code to make it generally available.

https://github.com/llvm/llvm-project/pull/116275