[llvm] [Utils] Avoid repeated hash lookups (NFC) (PR #129990)

[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/129990.diff


1 Files Affected:

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


``````````diff
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index c71605c500686..eb03689f31949 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -5833,9 +5833,10 @@ static bool eliminateDeadSwitchCases(SwitchInst *SI, DomTreeUpdater *DTU,
   for (const auto &Case : SI->cases()) {
     auto *Successor = Case.getCaseSuccessor();
     if (DTU) {
-      if (!NumPerSuccessorCases.count(Successor))
+      auto [It, Inserted] = NumPerSuccessorCases.try_emplace(Successor);
+      if (Inserted)
         UniqueSuccessors.push_back(Successor);
-      ++NumPerSuccessorCases[Successor];
+      ++It->second;
     }
     const APInt &CaseVal = Case.getCaseValue()->getValue();
     if (Known.Zero.intersects(CaseVal) || !Known.One.isSubsetOf(CaseVal) ||

``````````

</details>


https://github.com/llvm/llvm-project/pull/129990