[CodeGen, Transforms] Use *Map::lookup (NFC)

include/llvm/CodeGen/ScheduleDAGInstrs.h

@@ -388,10 +388,7 @@ namespace llvm {
 
   /// Returns an existing SUnit for this MI, or nullptr.
   inline SUnit *ScheduleDAGInstrs::getSUnit(MachineInstr *MI) const {
-    DenseMap<MachineInstr*, SUnit*>::const_iterator I = MISUnitMap.find(MI);
-    if (I == MISUnitMap.end())
-      return nullptr;
-    return I->second;
+    return MISUnitMap.lookup(MI);
   }
 
 } // end namespace llvm

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -787,8 +787,7 @@ public:
   }
 
   unsigned getStringTypeLoc(const DIStringType *ST) const {
-    auto I = StringTypeLocMap.find(ST);
-    return I != StringTypeLocMap.end() ? I->second : 0;
+    return StringTypeLocMap.lookup(ST);
   }
 
   void addStringTypeLoc(const DIStringType *ST, unsigned Loc) {

lib/CodeGen/MIRParser/MIParser.cpp

@@ -369,10 +369,7 @@ static void initSlots2Values(const Function &F,
 const Value* PerFunctionMIParsingState::getIRValue(unsigned Slot) {
   if (Slots2Values.empty())
     initSlots2Values(MF.getFunction(), Slots2Values);
-  auto ValueInfo = Slots2Values.find(Slot);
-  if (ValueInfo == Slots2Values.end())
-    return nullptr;
-  return ValueInfo->second;
+  return Slots2Values.lookup(Slot);
 }
 
 namespace {
@@ -3169,10 +3166,7 @@ static void initSlots2BasicBlocks(
 static const BasicBlock *getIRBlockFromSlot(
     unsigned Slot,
     const DenseMap<unsigned, const BasicBlock *> &Slots2BasicBlocks) {
-  auto BlockInfo = Slots2BasicBlocks.find(Slot);
-  if (BlockInfo == Slots2BasicBlocks.end())
-    return nullptr;
-  return BlockInfo->second;
+  return Slots2BasicBlocks.lookup(Slot);
 }
 
 const BasicBlock *MIParser::getIRBlock(unsigned Slot) {

lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -273,12 +273,7 @@ bool PointerReplacer::collectUsers(Instruction &I) {
   return true;
 }
 
-Value *PointerReplacer::getReplacement(Value *V) {
-  auto Loc = WorkMap.find(V);
-  if (Loc != WorkMap.end())
-    return Loc->second;
-  return nullptr;
-}
+Value *PointerReplacer::getReplacement(Value *V) { return WorkMap.lookup(V); }
 
 void PointerReplacer::replace(Instruction *I) {
   if (getReplacement(I))

lib/Transforms/Utils/Evaluator.cpp

@@ -210,11 +210,7 @@ static Constant *getInitializer(Constant *C) {
 Constant *Evaluator::ComputeLoadResult(Constant *P) {
   // If this memory location has been recently stored, use the stored value: it
   // is the most up-to-date.
-  auto findMemLoc = [this](Constant *Ptr) {
-    DenseMap<Constant *, Constant *>::const_iterator I =
-        MutatedMemory.find(Ptr);
-    return I != MutatedMemory.end() ? I->second : nullptr;
-  };
+  auto findMemLoc = [this](Constant *Ptr) { return MutatedMemory.lookup(Ptr); };
 
   if (Constant *Val = findMemLoc(P))
     return Val;

lib/Transforms/Utils/SSAUpdater.cpp

@@ -64,8 +64,7 @@ bool SSAUpdater::HasValueForBlock(BasicBlock *BB) const {
 }
 
 Value *SSAUpdater::FindValueForBlock(BasicBlock *BB) const {
-  AvailableValsTy::iterator AVI = getAvailableVals(AV).find(BB);
-  return (AVI != getAvailableVals(AV).end()) ? AVI->second : nullptr;
+  return getAvailableVals(AV).lookup(BB);
 }
 
 void SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) {

lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -1840,18 +1840,10 @@ private:
   }
 #endif
 
-  TreeEntry *getTreeEntry(Value *V) {
-    auto I = ScalarToTreeEntry.find(V);
-    if (I != ScalarToTreeEntry.end())
-      return I->second;
-    return nullptr;
-  }
+  TreeEntry *getTreeEntry(Value *V) { return ScalarToTreeEntry.lookup(V); }
 
   const TreeEntry *getTreeEntry(Value *V) const {
-    auto I = ScalarToTreeEntry.find(V);
-    if (I != ScalarToTreeEntry.end())
-      return I->second;
-    return nullptr;
+    return ScalarToTreeEntry.lookup(V);
   }
 
   /// Maps a specific scalar to its tree entry.

lib/Transforms/Vectorize/VPlan.h

@@ -2013,9 +2013,7 @@ public:
   /// \returns nullptr if doesn't have such group.
   InterleaveGroup<VPInstruction> *
   getInterleaveGroup(VPInstruction *Instr) const {
-    if (InterleaveGroupMap.count(Instr))
-      return InterleaveGroupMap.find(Instr)->second;
-    return nullptr;
+    return InterleaveGroupMap.lookup(Instr);
   }
 };