[llvm] [Vectorize] Avoid repeated hash lookups (NFC) (PR #132661)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-vectorizers

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/132661.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/LoopVectorize.cpp (+3-2) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 92160a421e59c..ae55049c22338 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5815,12 +5815,13 @@ LoopVectorizationCostModel::getReductionPatternCost(Instruction *I,
 
   // Test if the found instruction is a reduction, and if not return an invalid
   // cost specifying the parent to use the original cost modelling.
-  if (!InLoopReductionImmediateChains.count(RetI))
+  auto RetIIt = InLoopReductionImmediateChains.find(RetI);
+  if (RetIIt == InLoopReductionImmediateChains.end())
     return std::nullopt;
 
   // Find the reduction this chain is a part of and calculate the basic cost of
   // the reduction on its own.
-  Instruction *LastChain = InLoopReductionImmediateChains.at(RetI);
+  Instruction *LastChain = RetIIt->second;
   Instruction *ReductionPhi = LastChain;
   while (!isa<PHINode>(ReductionPhi))
     ReductionPhi = InLoopReductionImmediateChains.at(ReductionPhi);

``````````

</details>


https://github.com/llvm/llvm-project/pull/132661