[lld] [lld-macho] Parallelize ObjFile::sourceFile() during STABS emission. (PR #222087)

[Ellis Hoag via llvm-commits]

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@@ -1263,10 +1262,22 @@ void SymtabSection::emitStabs() {
 
   llvm::stable_sort(symbolsNeedingStabs, llvm::less_second());
 
+  std::vector<ObjFile *> stabFiles;
+  for (const SortingPair &pair : symbolsNeedingStabs) {
+    ObjFile *file = cast<ObjFile>(pair.first->originalIsec->getFile());
+    if (stabFiles.empty() || stabFiles.back() != file)
+      stabFiles.push_back(file);
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ellishg wrote:

Is there an existing test that thoroughly stresses this file deduplication logic? If not, I think we should add one.

https://github.com/llvm/llvm-project/pull/222087