[llvm] [X86] Avoid repeated hash lookups (NFC) (PR #127579)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/127579.diff


1 Files Affected:

- (modified) llvm/lib/Target/X86/X86LoadValueInjectionLoadHardening.cpp (+3-3) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86LoadValueInjectionLoadHardening.cpp b/llvm/lib/Target/X86/X86LoadValueInjectionLoadHardening.cpp
index 31a93f9c2a6ef..c9e495c1eba1f 100644
--- a/llvm/lib/Target/X86/X86LoadValueInjectionLoadHardening.cpp
+++ b/llvm/lib/Target/X86/X86LoadValueInjectionLoadHardening.cpp
@@ -339,10 +339,10 @@ X86LoadValueInjectionLoadHardeningPass::getGadgetGraph(
   DenseMap<MachineInstr *, GraphIter> NodeMap;
   int FenceCount = 0, GadgetCount = 0;
   auto MaybeAddNode = [&NodeMap, &Builder](MachineInstr *MI) {
-    auto Ref = NodeMap.find(MI);
-    if (Ref == NodeMap.end()) {
+    auto [Ref, Inserted] = NodeMap.try_emplace(MI);
+    if (Inserted) {
       auto I = Builder.addVertex(MI);
-      NodeMap[MI] = I;
+      Ref->second = I;
       return std::pair<GraphIter, bool>{I, true};
     }
     return std::pair<GraphIter, bool>{Ref->getSecond(), false};

``````````

</details>


https://github.com/llvm/llvm-project/pull/127579