[llvm] [Bitcode] Avoid repeated hash lookups (NFC) (PR #128824)

[Nikita Popov via llvm-commits]

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@@ -539,9 +539,10 @@ class MetadataLoader::MetadataLoaderImpl {
       if (!Visited.insert(S).second)
         break;
     }
-    ParentSubprogram[InitialScope] = llvm::dyn_cast_or_null<DISubprogram>(S);
 
-    return ParentSubprogram[InitialScope];
+    auto &PS = ParentSubprogram[InitialScope];
+    PS = llvm::dyn_cast_or_null<DISubprogram>(S);
+    return PS;
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nikic wrote:

I'd either directly return the assignment here, or use a local variable for `llvm::dyn_cast_or_null<DISubprogram>(S)` (or just repeat the expression).

https://github.com/llvm/llvm-project/pull/128824