[llvm] Value-initialize values with *Map::try_emplace (NFC) (#141522)

try_emplace value-initializes values, so we do not need to pass
nullptr to try_emplace when the value types are raw pointers or
std::unique_ptr<T>.

Author: kazutakahirata

llvm/include/llvm/CodeGen/DebugHandlerBase.h

@@ -101,12 +101,12 @@ class DebugHandlerBase : public AsmPrinterHandler {
 
   /// Ensure that a label will be emitted before MI.
   void requestLabelBeforeInsn(const MachineInstr *MI) {
-    LabelsBeforeInsn.insert(std::make_pair(MI, nullptr));
+    LabelsBeforeInsn.try_emplace(MI);
   }
 
   /// Ensure that a label will be emitted after MI.
   void requestLabelAfterInsn(const MachineInstr *MI) {
-    LabelsAfterInsn.insert(std::make_pair(MI, nullptr));
+    LabelsAfterInsn.try_emplace(MI);
   }
 
   virtual void beginFunctionImpl(const MachineFunction *MF) = 0;

llvm/include/llvm/SandboxIR/Context.h

@@ -253,7 +253,7 @@ class Context {
   Type *getType(llvm::Type *LLVMTy) {
     if (LLVMTy == nullptr)
       return nullptr;
-    auto Pair = LLVMTypeToTypeMap.insert({LLVMTy, nullptr});
+    auto Pair = LLVMTypeToTypeMap.try_emplace(LLVMTy);
     auto It = Pair.first;
     if (Pair.second)
       It->second = std::unique_ptr<Type, TypeDeleter>(new Type(LLVMTy, *this));

llvm/include/llvm/Transforms/Instrumentation/CFGMST.h

@@ -305,13 +305,13 @@ template <class Edge, class BBInfo> class CFGMST {
     uint32_t Index = BBInfos.size();
     auto Iter = BBInfos.end();
     bool Inserted;
-    std::tie(Iter, Inserted) = BBInfos.insert(std::make_pair(Src, nullptr));
+    std::tie(Iter, Inserted) = BBInfos.try_emplace(Src);
     if (Inserted) {
       // Newly inserted, update the real info.
       Iter->second = std::make_unique<BBInfo>(Index);
       Index++;
     }
-    std::tie(Iter, Inserted) = BBInfos.insert(std::make_pair(Dest, nullptr));
+    std::tie(Iter, Inserted) = BBInfos.try_emplace(Dest);
     if (Inserted)
       // Newly inserted, update the real info.
       Iter->second = std::make_unique<BBInfo>(Index);

llvm/lib/Analysis/BasicAliasAnalysis.cpp

@@ -216,7 +216,7 @@ bool EarliestEscapeAnalysis::isNotCapturedBefore(const Value *Object,
   if (!isIdentifiedFunctionLocal(Object))
     return false;
 
-  auto Iter = EarliestEscapes.insert({Object, nullptr});
+  auto Iter = EarliestEscapes.try_emplace(Object);
   if (Iter.second) {
     Instruction *EarliestCapture = FindEarliestCapture(
         Object, *const_cast<Function *>(DT.getRoot()->getParent()),

llvm/lib/Analysis/LoopAccessAnalysis.cpp

@@ -2979,7 +2979,7 @@ void LoopAccessInfo::print(raw_ostream &OS, unsigned Depth) const {
 }
 
 const LoopAccessInfo &LoopAccessInfoManager::getInfo(Loop &L) {
-  const auto &[It, Inserted] = LoopAccessInfoMap.insert({&L, nullptr});
+  const auto &[It, Inserted] = LoopAccessInfoMap.try_emplace(&L);
 
   if (Inserted)
     It->second =

llvm/lib/Analysis/MemorySSA.cpp

@@ -1277,15 +1277,15 @@ MemorySSA::~MemorySSA() {
 }
 
 MemorySSA::AccessList *MemorySSA::getOrCreateAccessList(const BasicBlock *BB) {
-  auto Res = PerBlockAccesses.insert(std::make_pair(BB, nullptr));
+  auto Res = PerBlockAccesses.try_emplace(BB);
 
   if (Res.second)
     Res.first->second = std::make_unique<AccessList>();
   return Res.first->second.get();
 }
 
 MemorySSA::DefsList *MemorySSA::getOrCreateDefsList(const BasicBlock *BB) {
-  auto Res = PerBlockDefs.insert(std::make_pair(BB, nullptr));
+  auto Res = PerBlockDefs.try_emplace(BB);
 
   if (Res.second)
     Res.first->second = std::make_unique<DefsList>();

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -4470,7 +4470,7 @@ GCMetadataPrinter *AsmPrinter::getOrCreateGCPrinter(GCStrategy &S) {
   if (!S.usesMetadata())
     return nullptr;
 
-  auto [GCPI, Inserted] = GCMetadataPrinters.insert({&S, nullptr});
+  auto [GCPI, Inserted] = GCMetadataPrinters.try_emplace(&S);
   if (!Inserted)
     return GCPI->second.get();
 

llvm/lib/CodeGen/MIRParser/MIParser.cpp

@@ -326,7 +326,7 @@ PerFunctionMIParsingState::PerFunctionMIParsingState(MachineFunction &MF,
 }
 
 VRegInfo &PerFunctionMIParsingState::getVRegInfo(Register Num) {
-  auto I = VRegInfos.insert(std::make_pair(Num, nullptr));
+  auto I = VRegInfos.try_emplace(Num);
   if (I.second) {
     MachineRegisterInfo &MRI = MF.getRegInfo();
     VRegInfo *Info = new (Allocator) VRegInfo;
@@ -339,7 +339,7 @@ VRegInfo &PerFunctionMIParsingState::getVRegInfo(Register Num) {
 VRegInfo &PerFunctionMIParsingState::getVRegInfoNamed(StringRef RegName) {
   assert(RegName != "" && "Expected named reg.");
 
-  auto I = VRegInfosNamed.insert(std::make_pair(RegName.str(), nullptr));
+  auto I = VRegInfosNamed.try_emplace(RegName.str());
   if (I.second) {
     VRegInfo *Info = new (Allocator) VRegInfo;
     Info->VReg = MF.getRegInfo().createIncompleteVirtualRegister(RegName);

llvm/lib/IR/Constants.cpp

@@ -2876,9 +2876,7 @@ Constant *ConstantDataSequential::getImpl(StringRef Elements, Type *Ty) {
 
   // Do a lookup to see if we have already formed one of these.
   auto &Slot =
-      *Ty->getContext()
-           .pImpl->CDSConstants.insert(std::make_pair(Elements, nullptr))
-           .first;
+      *Ty->getContext().pImpl->CDSConstants.try_emplace(Elements).first;
 
   // The bucket can point to a linked list of different CDS's that have the same
   // body but different types.  For example, 0,0,0,1 could be a 4 element array

llvm/lib/Object/ELF.cpp

@@ -965,8 +965,7 @@ ELFFile<ELFT>::getSectionAndRelocations(
       continue;
     }
     if (*DoesSectionMatch) {
-      if (SecToRelocMap.insert(std::make_pair(&Sec, (const Elf_Shdr *)nullptr))
-              .second)
+      if (SecToRelocMap.try_emplace(&Sec).second)
         continue;
     }