[llvm] [AMDGPU] Avoid repeated hash lookups (NFC) (PR #128393)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/128393.diff


1 Files Affected:

- (modified) llvm/lib/Target/AMDGPU/SIFoldOperands.cpp (+3-5) 


``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index fa15e73bc31d5..641365d319a50 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -1084,13 +1084,11 @@ void SIFoldOperandsImpl::foldOperand(
           }
 
           if (CopyToVGPR.Reg) {
-            Register Vgpr;
-            if (VGPRCopies.count(CopyToVGPR)) {
-              Vgpr = VGPRCopies[CopyToVGPR];
-            } else {
+            auto [It, Inserted] = VGPRCopies.try_emplace(CopyToVGPR);
+            Register &Vgpr = It->second;
+            if (Inserted) {
               Vgpr = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
               BuildMI(MBB, UseMI, DL, TII->get(AMDGPU::COPY), Vgpr).add(*Def);
-              VGPRCopies[CopyToVGPR] = Vgpr;
             }
             auto Tmp = MRI->createVirtualRegister(&AMDGPU::AGPR_32RegClass);
             BuildMI(MBB, UseMI, DL,

``````````

</details>


https://github.com/llvm/llvm-project/pull/128393