[lld] [lld] Merge equivalent symbols found during ICF (PR #134342)

[Pranav Kant via llvm-commits]

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@@ -333,6 +333,28 @@ bool ICF<ELFT>::equalsConstant(const InputSection *a, const InputSection *b) {
              : constantEq(a, ra.relas, b, rb.relas);
 }
 
+template <class RelTy>
+static SmallVector<Symbol *> getReloc(const InputSection *sec,
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pranavk wrote:

We are still replacing the input file symbols as suggested in the original comment by James. 

The reason I am scanning the relocation here is to make code thread-safe. Original diff by James is not thread-safe as `variableEq` is called in parallel for larger links. So annotating symbols as equivalent in that function is going to be problematic. 

https://github.com/llvm/llvm-project/pull/134342