[llvm] [Scalar] Avoid repeated hash lookups (NFC) (PR #168217)

[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/168217.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp (+1-2) 


``````````diff
diff --git a/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
index a62804d3ef201..e5399bdd767e2 100644
--- a/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
@@ -1275,8 +1275,7 @@ bool StraightLineStrengthReduce::runOnFunction(Function &F) {
   // Build the dependency graph and sort candidate instructions from dependency
   // roots to leaves
   for (auto &C : Candidates) {
-    if (DependencyGraph.find(C.Ins) == DependencyGraph.end())
-      DependencyGraph[C.Ins] = {};
+    DependencyGraph.try_emplace(C.Ins);
     addDependency(C, C.Basis);
   }
   sortCandidateInstructions();

``````````

</details>


https://github.com/llvm/llvm-project/pull/168217