[lld] [lld-macho] Category Merger: add support for addrsig references (PR #90903)

[Kyungwoo Lee via llvm-commits]

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@@ -478,6 +482,8 @@ class ObjcCategoryMerger {
   std::vector<ConcatInputSection *> &allInputSections;
   // Map of base class Symbol to list of InfoInputCategory's for it
   DenseMap<const Symbol *, std::vector<InfoInputCategory>> categoryMap;
+  // Set for tracking InputSection erased via eraseISec
+  std::unordered_set<InputSection *> erasedIsecs;
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kyulee-com wrote:

If the data tends to be large, you could use `DenseSet` as opposed to `SmallPtrSet`, both of which are unordered, similar to `unordered_set`. I don't expect much perf distinction in the usage here which temporarily tracks the erased isec like a visited set, so using either one shouldn't matter. But it's more on coding convention or preference on llvm data-structure.

https://github.com/llvm/llvm-project/pull/90903