[llvm] [Coroutines] Avoid repeated hash lookups (NFC) (PR #126466)

[via llvm-commits]

llvmbot wrote:


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

@llvm/pr-subscribers-coroutines

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/126466.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp (+3-2) 


``````````diff
diff --git a/llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp b/llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp
index 3686c7c153999c..5021425152f6cc 100644
--- a/llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp
+++ b/llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp
@@ -70,11 +70,12 @@ struct RematGraph {
                std::deque<std::unique_ptr<RematNode>> &WorkList,
                User *FirstUse) {
     RematNode *N = NUPtr.get();
-    if (Remats.count(N->Node))
+    auto [It, Inserted] = Remats.try_emplace(N->Node);
+    if (!Inserted)
       return;
 
     // We haven't see this node yet - add to the list
-    Remats[N->Node] = std::move(NUPtr);
+    It->second = std::move(NUPtr);
     for (auto &Def : N->Node->operands()) {
       Instruction *D = dyn_cast<Instruction>(Def.get());
       if (!D || !MaterializableCallback(*D) ||

``````````

</details>


https://github.com/llvm/llvm-project/pull/126466