2 files changed, 3 insertions, 8 deletions
diff --git a/lld/COFF/InputFiles.cpp b/lld/COFF/InputFiles.cpp
index 66d792ba4cf..be5c0ed721c 100644
--- a/lld/COFF/InputFiles.cpp
+++ b/lld/COFF/InputFiles.cpp
@@ -71,12 +71,6 @@ std::error_code ArchiveFile::parse() {
     if (B->getName() != "__NULL_IMPORT_DESCRIPTOR")
       LazySymbols.push_back(B);
   }
-
-  // Seen is a map from member files to boolean values. Initially
-  // all members are mapped to false, which indicates all these files
-  // are not read yet.
-  for (const Archive::Child &Child : File->children())
-    Seen[Child.getBuffer().data()].clear();
   return std::error_code();
 }
 
@@ -90,7 +84,8 @@ ErrorOr<MemoryBufferRef> ArchiveFile::getMember(const Archive::Symbol *Sym) {
 
   // Return an empty buffer if we have already returned the same buffer.
   const char *StartAddr = It->getBuffer().data();
-  if (Seen[StartAddr].test_and_set())
+  auto Pair = Seen.insert(StartAddr);
+  if (!Pair.second)
     return MemoryBufferRef();
   return It->getMemoryBufferRef();
 }
diff --git a/lld/COFF/InputFiles.h b/lld/COFF/InputFiles.h
index 0d768c52ea2..ade0b25f2fb 100644
--- a/lld/COFF/InputFiles.h
+++ b/lld/COFF/InputFiles.h
@@ -107,7 +107,7 @@ private:
   std::unique_ptr<Archive> File;
   std::string Filename;
   std::vector<Lazy *> LazySymbols;
-  std::map<const char *, std::atomic_flag> Seen;
+  std::set<const char *> Seen;
   llvm::MallocAllocator Alloc;
 };