[llvm] db3fdbc - [CodeGen] Avoid repeated hash lookups (NFC) (#130889)

[via llvm-commits]

Author: Kazu Hirata
Date: 2025-03-12T08:47:36-07:00
New Revision: db3fdbc84beb9b1f60290880e87a0c7050ac814e

URL: https://github.com/llvm/llvm-project/commit/db3fdbc84beb9b1f60290880e87a0c7050ac814e
DIFF: https://github.com/llvm/llvm-project/commit/db3fdbc84beb9b1f60290880e87a0c7050ac814e.diff

LOG: [CodeGen] Avoid repeated hash lookups (NFC) (#130889)

Added: 
    

Modified: 
    llvm/lib/CodeGen/LiveRangeShrink.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/LiveRangeShrink.cpp b/llvm/lib/CodeGen/LiveRangeShrink.cpp
index bb824566047e1..dae7e14e54aae 100644
--- a/llvm/lib/CodeGen/LiveRangeShrink.cpp
+++ b/llvm/lib/CodeGen/LiveRangeShrink.cpp
@@ -153,13 +153,13 @@ bool LiveRangeShrink::runOnMachineFunction(MachineFunction &MF) {
           continue;
         if (MO.isUse())
           UseMap[MO.getReg()] = std::make_pair(CurrentOrder, &MI);
-        else if (MO.isDead() && UseMap.count(MO.getReg()))
+        else if (MO.isDead()) {
           // Barrier is the last instruction where MO get used. MI should not
           // be moved above Barrier.
-          if (Barrier < UseMap[MO.getReg()].first) {
-            Barrier = UseMap[MO.getReg()].first;
-            BarrierMI = UseMap[MO.getReg()].second;
-          }
+          auto It = UseMap.find(MO.getReg());
+          if (It != UseMap.end() && Barrier < It->second.first)
+            std::tie(Barrier, BarrierMI) = It->second;
+        }
       }
 
       if (!MI.isSafeToMove(SawStore)) {