[CodeGen] Avoid repeated hash lookups (NFC) (#132513)

kazutakahirata · web-flow · commit cb729be11cbf · 2025-03-22T08:08:28.000-07:00
diff --git a/llvm/lib/CodeGen/GCMetadata.cpp b/llvm/lib/CodeGen/GCMetadata.cpp
@@ -41,8 +41,10 @@ CollectorMetadataAnalysis::run(Module &M, ModuleAnalysisManager &MAM) {
   for (auto &F : M) {
     if (F.isDeclaration() || !F.hasGC())
       continue;
-    if (auto GCName = F.getGC(); !Map.contains(GCName))
-      Map[GCName] = getGCStrategy(GCName);
+    auto GCName = F.getGC();
+    auto [It, Inserted] = Map.try_emplace(GCName);
+    if (Inserted)
+      It->second = getGCStrategy(GCName);
   }
   return R;
 }

Original file line number	Diff line number	Diff line change
`@@ -41,8 +41,10 @@ CollectorMetadataAnalysis::run(Module &M, ModuleAnalysisManager &MAM) {`
`41`	`41`	`for (auto &F : M) {`
`42`	`42`	`if (F.isDeclaration() \|\| !F.hasGC())`
`43`	`43`	`continue;`
`44`		`- if (auto GCName = F.getGC(); !Map.contains(GCName))`
`45`		`- Map[GCName] = getGCStrategy(GCName);`
	`44`	`+ auto GCName = F.getGC();`
	`45`	`+ auto [It, Inserted] = Map.try_emplace(GCName);`
	`46`	`+ if (Inserted)`
	`47`	`+ It->second = getGCStrategy(GCName);`
`46`	`48`	`}`
`47`	`49`	`return R;`
`48`	`50`	`}`