[llvm] [Utils] Avoid repeated hash lookups (NFC) (PR #127171)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/127171.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp (+3-2) 


``````````diff
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
index 89cfee2acd82c..054b0ba2ba664 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
@@ -395,8 +395,9 @@ llvm::UnrollAndJamLoop(Loop *L, unsigned Count, unsigned TripCount,
       }
 
       // Update our running maps of newest clones
-      PrevItValueMap[New] = (It == 1 ? *BB : LastValueMap[*BB]);
-      LastValueMap[*BB] = New;
+      auto &Last = LastValueMap[*BB];
+      PrevItValueMap[New] = (It == 1 ? *BB : Last);
+      Last = New;
       for (ValueToValueMapTy::iterator VI = VMap.begin(), VE = VMap.end();
            VI != VE; ++VI) {
         PrevItValueMap[VI->second] =

``````````

</details>


https://github.com/llvm/llvm-project/pull/127171