[llvm] [SPIRV] Avoid repeated hash lookups (NFC) (PR #128398)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-spir-v

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/128398.diff


1 Files Affected:

- (modified) llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h (+4-6) 


``````````diff
diff --git a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h
index c7f846b8e9bcc..2b3599259a739 100644
--- a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h
+++ b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h
@@ -197,12 +197,10 @@ struct ModuleAnalysisInfo {
   // Convert MBB's number to corresponding ID register.
   Register getOrCreateMBBRegister(const MachineBasicBlock &MBB) {
     auto Key = std::make_pair(MBB.getParent(), MBB.getNumber());
-    auto It = BBNumToRegMap.find(Key);
-    if (It != BBNumToRegMap.end())
-      return It->second;
-    Register NewReg = Register::index2VirtReg(getNextID());
-    BBNumToRegMap[Key] = NewReg;
-    return NewReg;
+    auto [It, Inserted] = BBNumToRegMap.try_emplace(Key);
+    if (Inserted)
+      It->second = Register::index2VirtReg(getNextID());
+    return It->second;
   }
 };
 } // namespace SPIRV

``````````

</details>


https://github.com/llvm/llvm-project/pull/128398