[lld] [lld-macho] Implement ObjC category merging (-objc_category_merging) (PR #82928)

[Jez Ng via llvm-commits]

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@@ -203,6 +205,8 @@ void macho::writeMapFile() {
     for (const OutputSection *osec : seg->getSections()) {
       if (auto *concatOsec = dyn_cast<ConcatOutputSection>(osec)) {
         for (const InputSection *isec : concatOsec->inputs) {
+          if (isec->isLinkOptimizedAway())
+            continue;
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int3 wrote:

can we filter these out in `gatherInputSections` instead of doing it here?

(though as per comment on the gdoc, I would prefer if we just used the existing ICF/live flags since there should already be logic for handling those

https://github.com/llvm/llvm-project/pull/82928