[lld] [lld][BP] Avoid ordering ICF'ed sections (PR #126327)

[Ellis Hoag via llvm-commits]

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@@ -117,6 +117,8 @@ DenseMap<const InputSection *, int> lld::macho::runBalancedPartitioning(
         auto *isec = subsec.isec;
         if (!isec || isec->data.empty())
           continue;
+        if (isa<ConcatInputSection>(isec) && !isec->isLive(0))
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ellishg wrote:

I should add a comment here. 
https://github.com/llvm/llvm-project/blob/62ae876b1ba2f03bb125174aa24e30b4ebd351a5/lld/MachO/InputSection.h#L113-L114

I actually don't know if `isec` could be some other `InputSection`, but I didn't see any examples in my large test binary.

https://github.com/llvm/llvm-project/pull/126327