[C++11] More 'nullptr' conversion or in some cases just using a boolean check instead of comparing to nullptr.

llvm-svn: 205831
diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 3079f0a..94d7deb 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -27,7 +27,7 @@
 ValueSymbolTable *BasicBlock::getValueSymbolTable() {
   if (Function *F = getParent())
     return &F->getValueSymbolTable();
-  return 0;
+  return nullptr;
 }
 
 const DataLayout *BasicBlock::getDataLayout() const {
@@ -45,7 +45,7 @@
 
 BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent,
                        BasicBlock *InsertBefore)
-  : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(0) {
+  : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(nullptr) {
 
   // Make sure that we get added to a function
   LeakDetector::addGarbageObject(this);
@@ -122,12 +122,12 @@
 
 
 TerminatorInst *BasicBlock::getTerminator() {
-  if (InstList.empty()) return 0;
+  if (InstList.empty()) return nullptr;
   return dyn_cast<TerminatorInst>(&InstList.back());
 }
 
 const TerminatorInst *BasicBlock::getTerminator() const {
-  if (InstList.empty()) return 0;
+  if (InstList.empty()) return nullptr;
   return dyn_cast<TerminatorInst>(&InstList.back());
 }
 
@@ -186,10 +186,10 @@
 /// return the block, otherwise return a null pointer.
 BasicBlock *BasicBlock::getSinglePredecessor() {
   pred_iterator PI = pred_begin(this), E = pred_end(this);
-  if (PI == E) return 0;         // No preds.
+  if (PI == E) return nullptr;         // No preds.
   BasicBlock *ThePred = *PI;
   ++PI;
-  return (PI == E) ? ThePred : 0 /*multiple preds*/;
+  return (PI == E) ? ThePred : nullptr /*multiple preds*/;
 }
 
 /// getUniquePredecessor - If this basic block has a unique predecessor block,
@@ -199,12 +199,12 @@
 /// a switch statement with multiple cases having the same destination).
 BasicBlock *BasicBlock::getUniquePredecessor() {
   pred_iterator PI = pred_begin(this), E = pred_end(this);
-  if (PI == E) return 0; // No preds.
+  if (PI == E) return nullptr; // No preds.
   BasicBlock *PredBB = *PI;
   ++PI;
   for (;PI != E; ++PI) {
     if (*PI != PredBB)
-      return 0;
+      return nullptr;
     // The same predecessor appears multiple times in the predecessor list.
     // This is OK.
   }
@@ -277,7 +277,7 @@
       PN->removeIncomingValue(Pred, false);
       // If all incoming values to the Phi are the same, we can replace the Phi
       // with that value.
-      Value* PNV = 0;
+      Value* PNV = nullptr;
       if (!DontDeleteUselessPHIs && (PNV = PN->hasConstantValue()))
         if (PNV != PN) {
           PN->replaceAllUsesWith(PNV);