[llvm] 9f83914 - [IPO] Avoid repeated hash lookups (NFC) (#130389)

[via llvm-commits]

Author: Kazu Hirata
Date: 2025-03-08T01:01:34-08:00
New Revision: 9f83914880ad786196fb0a9658ef2c467fb23074

URL: https://github.com/llvm/llvm-project/commit/9f83914880ad786196fb0a9658ef2c467fb23074
DIFF: https://github.com/llvm/llvm-project/commit/9f83914880ad786196fb0a9658ef2c467fb23074.diff

LOG: [IPO] Avoid repeated hash lookups (NFC) (#130389)

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/GlobalDCE.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/IPO/GlobalDCE.cpp b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
index eca36fb31cea0..250c0443cb4af 100644
--- a/llvm/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -67,16 +67,13 @@ void GlobalDCEPass::ComputeDependencies(Value *V,
     Deps.insert(GV);
   } else if (auto *CE = dyn_cast<Constant>(V)) {
     // Avoid walking the whole tree of a big ConstantExprs multiple times.
-    auto Where = ConstantDependenciesCache.find(CE);
-    if (Where != ConstantDependenciesCache.end()) {
-      auto const &K = Where->second;
-      Deps.insert(K.begin(), K.end());
-    } else {
-      SmallPtrSetImpl<GlobalValue *> &LocalDeps = ConstantDependenciesCache[CE];
+    auto [Where, Inserted] = ConstantDependenciesCache.try_emplace(CE);
+    SmallPtrSetImpl<GlobalValue *> &LocalDeps = Where->second;
+    if (Inserted) {
       for (User *CEUser : CE->users())
         ComputeDependencies(CEUser, LocalDeps);
-      Deps.insert(LocalDeps.begin(), LocalDeps.end());
     }
+    Deps.insert(LocalDeps.begin(), LocalDeps.end());
   }
 }