[clang] [clang-linker-wrapper] Avoid repeated hash lookups (NFC) (PR #127443)

[Nikita Popov via cfe-commits]

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@@ -1060,8 +1060,9 @@ Expected<bool> getSymbolsFromBitcode(MemoryBufferRef Buffer, OffloadKind Kind,
       if (Sym.isFormatSpecific() || !Sym.isGlobal())
         continue;
 
-      bool NewSymbol = Syms.count(Sym.getName()) == 0;
-      auto OldSym = NewSymbol ? Sym_None : Syms[Sym.getName()];
+      auto It = Syms.find(Sym.getName());
+      bool NewSymbol = It == Syms.end();
+      auto OldSym = NewSymbol ? Sym_None : It->second;
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nikic wrote:

Could also reduce this to `Syms.lookup(Sym.getName())`, but maybe that's less explicit...

https://github.com/llvm/llvm-project/pull/127443