[llvm] [TableGen] Avoid repeated hash lookups (NFC) (PR #120873)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-tablegen

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/120873.diff


1 Files Affected:

- (modified) llvm/utils/TableGen/CallingConvEmitter.cpp (+5-4) 


``````````diff
diff --git a/llvm/utils/TableGen/CallingConvEmitter.cpp b/llvm/utils/TableGen/CallingConvEmitter.cpp
index 444b10719cb034..b315aa7d86fe91 100644
--- a/llvm/utils/TableGen/CallingConvEmitter.cpp
+++ b/llvm/utils/TableGen/CallingConvEmitter.cpp
@@ -378,10 +378,11 @@ void CallingConvEmitter::emitArgRegisterLists(raw_ostream &O) {
         const std::string &InnerCCName = InnerEntry.first;
         std::set<std::string> &InnerRegisters = InnerEntry.second;
 
-        if (InnerRegisters.find(CCName) != InnerRegisters.end()) {
-          AssignedRegsMap[InnerCCName].insert(AssignedRegsMap[CCName].begin(),
-                                              AssignedRegsMap[CCName].end());
-          InnerRegisters.erase(CCName);
+        auto It = InnerRegisters.find(CCName);
+        if (It != InnerRegisters.end()) {
+          const auto &Src = AssignedRegsMap[CCName];
+          AssignedRegsMap[InnerCCName].insert(Src.begin(), Src.end());
+          InnerRegisters.erase(It);
         }
       }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/120873