[AMDGPU] Avoid repeated hash lookups (NFC)

[kazutakahirata]

No description provided.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

Author: Kazu Hirata (kazutakahirata)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/130706.diff

1 Files Affected:

• (modified) llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp (+6-7)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp b/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp
index 8d3e7829e10e1..75eb440d99c03 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalize.cpp
@@ -89,13 +89,12 @@ const RegBankLegalizeRules &getRules(const GCNSubtarget &ST,
   static SmallDenseMap<unsigned, std::unique_ptr<RegBankLegalizeRules>>
       CacheForRuleSet;
   std::lock_guard<std::mutex> Lock(GlobalMutex);
-  if (!CacheForRuleSet.contains(ST.getGeneration())) {
-    auto Rules = std::make_unique<RegBankLegalizeRules>(ST, MRI);
-    CacheForRuleSet[ST.getGeneration()] = std::move(Rules);
-  } else {
-    CacheForRuleSet[ST.getGeneration()]->refreshRefs(ST, MRI);
-  }
-  return *CacheForRuleSet[ST.getGeneration()];
+  auto [It, Inserted] = CacheForRuleSet.try_emplace(ST.getGeneration());
+  if (Inserted)
+    It->second = std::make_unique<RegBankLegalizeRules>(ST, MRI);
+  else
+    It->second->refreshRefs(ST, MRI);
+  return *It->second;
 }
 
 class AMDGPURegBankLegalizeCombiner {