[lld] [lld-macho] icf objc stubs (PR #79730)

[Jez Ng via llvm-commits]

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@@ -814,11 +814,54 @@ ObjCStubsSection::ObjCStubsSection()
               : target->objcStubsSmallAlignment;
 }
 
+bool ObjCStubsSection::isObjCStubSymbol(Symbol *sym) {
+  return sym->getName().starts_with(symbolPrefix);
+}
+
+StringRef ObjCStubsSection::getMethName(Symbol *sym) {
+  assert(isObjCStubSymbol(sym) && "not an objc stub");
+  auto name = sym->getName();
+  StringRef methname = name.drop_front(symbolPrefix.size());
+  return methname;
+}
+
+void ObjCStubsSection::initialize() {
+  // Do not fold selrefs without ICF.
+  if (config->icfLevel == ICFLevel::none)
+    return;
+
+  // Search methnames already referenced in __objc_selrefs
+  // Map the name to the corresponding selref entry
+  // which we will reuse when creating objc stubs.
+  for (ConcatInputSection *isec : inputSections) {
+    if (isec->shouldOmitFromOutput())
+      continue;
+    if (isec->getName() != "__objc_selrefs")
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int3 wrote:

s/"__objc_selrefs"/section_names::objcSelrefs/

https://github.com/llvm/llvm-project/pull/79730