[llvm] 4113d79 - [NFC][CodeGen] Optimize hash table lookups in MachineBlockHashInfo (#192823)

[via llvm-commits]

Author: Vitaly Buka
Date: 2026-04-18T22:30:27-07:00
New Revision: 4113d79a20253cd34820d8ff2031c7e0307b9e66

URL: https://github.com/llvm/llvm-project/commit/4113d79a20253cd34820d8ff2031c7e0307b9e66
DIFF: https://github.com/llvm/llvm-project/commit/4113d79a20253cd34820d8ff2031c7e0307b9e66.diff

LOG: [NFC][CodeGen] Optimize hash table lookups in MachineBlockHashInfo (#192823)

Added: 
    

Modified: 
    llvm/lib/CodeGen/MachineBlockHashInfo.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/MachineBlockHashInfo.cpp b/llvm/lib/CodeGen/MachineBlockHashInfo.cpp
index 73dfc7c62a95c..f2f73f63bcc0c 100644
--- a/llvm/lib/CodeGen/MachineBlockHashInfo.cpp
+++ b/llvm/lib/CodeGen/MachineBlockHashInfo.cpp
@@ -66,18 +66,19 @@ bool MachineBlockHashInfo::runOnMachineFunction(MachineFunction &F) {
   uint16_t Offset = 0;
   // Initialize hash components
   for (const MachineBasicBlock &MBB : F) {
+    auto &HashInfo = HashInfos[&MBB];
     // offset of the machine basic block
-    HashInfos[&MBB].Offset = Offset;
-    Offset += MBB.size();
+    HashInfo.Offset = Offset + MBB.size();
     // Hashing opcodes
-    HashInfos[&MBB].OpcodeHash = hashBlock(MBB, /*HashOperands=*/false);
+    HashInfo.OpcodeHash = hashBlock(MBB, /*HashOperands=*/false);
     // Hash complete instructions
-    HashInfos[&MBB].InstrHash = hashBlock(MBB, /*HashOperands=*/true);
+    HashInfo.InstrHash = hashBlock(MBB, /*HashOperands=*/true);
   }
 
   // Initialize neighbor hash
   for (const MachineBasicBlock &MBB : F) {
-    uint64_t Hash = HashInfos[&MBB].OpcodeHash;
+    auto &HashInfo = HashInfos[&MBB];
+    uint64_t Hash = HashInfo.OpcodeHash;
     // Append hashes of successors
     for (const MachineBasicBlock *SuccMBB : MBB.successors()) {
       uint64_t SuccHash = HashInfos[SuccMBB].OpcodeHash;
@@ -88,7 +89,7 @@ bool MachineBlockHashInfo::runOnMachineFunction(MachineFunction &F) {
       uint64_t PredHash = HashInfos[PredMBB].OpcodeHash;
       Hash = hashing::detail::hash_16_bytes(Hash, PredHash);
     }
-    HashInfos[&MBB].NeighborHash = Hash;
+    HashInfo.NeighborHash = Hash;
   }
 
   // Assign hashes