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

[Kyungwoo Lee via llvm-commits]

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@@ -1183,26 +1193,66 @@ void ObjcCategoryMerger::eraseMergedCategories() {
   // the references to the ones we merged.
   generateCatListForNonErasedCategories(catListToErasedOffsets);
 
+  // We use erasedIsecs below to track erased sections so we can later remove
+  // references to it.
+  std::unordered_set<InputSection *> erasedIsecs;
+  erasedIsecs.reserve(categoryMap.size());
+
   // Erase the old method lists & names of the categories that were merged
   for (auto &mapEntry : categoryMap) {
     for (InfoInputCategory &catInfo : mapEntry.second) {
       if (!catInfo.wasMerged)
         continue;
 
+      erasedIsecs.insert(catInfo.catBodyIsec);
+      erasedIsecs.insert(catInfo.catListIsec);
+
       eraseISec(catInfo.catBodyIsec);
-      tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec, catLayout.nameOffset);
+      tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec, catLayout.nameOffset,
+                                  erasedIsecs);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
-                                  catLayout.instanceMethodsOffset);
+                                  catLayout.instanceMethodsOffset, erasedIsecs);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
-                                  catLayout.classMethodsOffset);
+                                  catLayout.classMethodsOffset, erasedIsecs);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
-                                  catLayout.protocolsOffset);
+                                  catLayout.protocolsOffset, erasedIsecs);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
-                                  catLayout.classPropsOffset);
+                                  catLayout.classPropsOffset, erasedIsecs);
       tryEraseDefinedAtIsecOffset(catInfo.catBodyIsec,
-                                  catLayout.instancePropsOffset);
+                                  catLayout.instancePropsOffset, erasedIsecs);
     }
   }
+
+  removeRefsToErasedIsecs(erasedIsecs);
+}
+
+// The compiler may generate references to categories inside the addrsig
+// section. This function will erase these references.
+void ObjcCategoryMerger::removeRefsToErasedIsecs(
+    std::unordered_set<InputSection *> erasedIsecs) {
+  for (InputSection *isec : inputSections) {
+    if (isec->getName() != section_names::addrSig)
+      continue;
+
+    auto removeRelocs = [&erasedIsecs](Reloc &r) {
+      ConcatInputSection *isec = nullptr;
+      isec = dyn_cast_or_null<ConcatInputSection>(
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kyulee-com wrote:

I think you can combine these two lines into one.

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