[llvm] [Transforms] Avoid repeated hash lookups (NFC) (PR #129359)

[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/129359.diff


1 Files Affected:

- (modified) llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h (+3-4) 


``````````diff
diff --git a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
index 390f284019bb4..d714dba4a9687 100644
--- a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
+++ b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
@@ -646,14 +646,13 @@ void SampleProfileLoaderBaseImpl<BT>::findEquivalenceClasses(FunctionT &F) {
     BasicBlockT *BB1 = &BB;
 
     // Compute BB1's equivalence class once.
-    if (EquivalenceClass.count(BB1)) {
+    // By default, blocks are in their own equivalence class.
+    auto [It, Inserted] = EquivalenceClass.try_emplace(BB1, BB1);
+    if (!Inserted) {
       LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
       continue;
     }
 
-    // By default, blocks are in their own equivalence class.
-    EquivalenceClass[BB1] = BB1;
-
     // Traverse all the blocks dominated by BB1. We are looking for
     // every basic block BB2 such that:
     //

``````````

</details>


https://github.com/llvm/llvm-project/pull/129359