[BPF] Avoid repeated map lookups (NFC)

Author: kazutakahirata

llvm/lib/Target/BPF/BTFDebug.cpp

@@ -1499,17 +1499,15 @@ void BTFDebug::processGlobals(bool ProcessingMapDef) {
       continue;
 
     // Find or create a DataSec
-    if (DataSecEntries.find(std::string(SecName)) == DataSecEntries.end()) {
-      DataSecEntries[std::string(SecName)] =
-          std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
-    }
+    auto [It, Inserted] = DataSecEntries.try_emplace(std::string(SecName));
+    if (Inserted)
+      It->second = std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
 
     // Calculate symbol size
     const DataLayout &DL = Global.getDataLayout();
     uint32_t Size = DL.getTypeAllocSize(Global.getValueType());
 
-    DataSecEntries[std::string(SecName)]->addDataSecEntry(VarId,
-        Asm->getSymbol(&Global), Size);
+    It->second->addDataSecEntry(VarId, Asm->getSymbol(&Global), Size);
 
     if (Global.hasInitializer())
       processGlobalInitializer(Global.getInitializer());
@@ -1609,14 +1607,12 @@ void BTFDebug::processFuncPrototypes(const Function *F) {
   if (F->hasSection()) {
     StringRef SecName = F->getSection();
 
-    if (DataSecEntries.find(std::string(SecName)) == DataSecEntries.end()) {
-      DataSecEntries[std::string(SecName)] =
-          std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
-    }
+    auto [It, Inserted] = DataSecEntries.try_emplace(std::string(SecName));
+    if (Inserted)
+      It->second = std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
 
     // We really don't know func size, set it to 0.
-    DataSecEntries[std::string(SecName)]->addDataSecEntry(FuncId,
-        Asm->getSymbol(F), 0);
+    It->second->addDataSecEntry(FuncId, Asm->getSymbol(F), 0);
   }
 }