[llvm] 09bf5b0 - [CodeGen] Avoid repeated hash lookups (NFC) (#123160)

[via llvm-commits]

Author: Kazu Hirata
Date: 2025-01-16T08:45:53-08:00
New Revision: 09bf5b0d3560992553b593b774c2d3dfff1cd683

URL: https://github.com/llvm/llvm-project/commit/09bf5b0d3560992553b593b774c2d3dfff1cd683
DIFF: https://github.com/llvm/llvm-project/commit/09bf5b0d3560992553b593b774c2d3dfff1cd683.diff

LOG: [CodeGen] Avoid repeated hash lookups (NFC) (#123160)

Added: 
    

Modified: 
    llvm/lib/CodeGen/MachineCSE.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp
index 0a547050e91a8a..728fd2f5f7cd4f 100644
--- a/llvm/lib/CodeGen/MachineCSE.cpp
+++ b/llvm/lib/CodeGen/MachineCSE.cpp
@@ -832,12 +832,11 @@ bool MachineCSEImpl::ProcessBlockPRE(MachineDominatorTree *DT,
     if (!isPRECandidate(&MI, PhysRefs))
       continue;
 
-    if (!PREMap.count(&MI)) {
-      PREMap[&MI] = MBB;
+    auto [It, Inserted] = PREMap.try_emplace(&MI, MBB);
+    if (Inserted)
       continue;
-    }
 
-    auto MBB1 = PREMap[&MI];
+    auto *MBB1 = It->second;
     assert(
         !DT->properlyDominates(MBB, MBB1) &&
         "MBB cannot properly dominate MBB1 while DFS through dominators tree!");