Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/compiler/optimizing/gvn.cc b/compiler/optimizing/gvn.cc
index 74848d5..708733e 100644
--- a/compiler/optimizing/gvn.cc
+++ b/compiler/optimizing/gvn.cc
@@ -55,7 +55,7 @@
         buckets_owned_(allocator, num_buckets_, false),
         num_entries_(to_copy.num_entries_) {
     // ArenaAllocator returns zeroed memory, so entries of buckets_ and
-    // buckets_owned_ are initialized to nullptr and false, respectively.
+    // buckets_owned_ are initialized to null and false, respectively.
     DCHECK(IsPowerOfTwo(num_buckets_));
     if (num_buckets_ == to_copy.num_buckets_) {
       // Hash table remains the same size. We copy the bucket pointers and leave
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index bef5896..6ab57b8 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -714,7 +714,7 @@
     // TODO: Implement static evaluation of long unary operations.
     //
     // Do not exit with a fatal condition here.  Instead, simply
-    // return `nullptr' to notify the caller that this instruction
+    // return `null' to notify the caller that this instruction
     // cannot (yet) be statically evaluated.
     return nullptr;
   }
@@ -750,7 +750,7 @@
 }
 
 // If `GetConstantRight()` returns one of the input, this returns the other
-// one. Otherwise it returns nullptr.
+// one. Otherwise it returns null.
 HInstruction* HBinaryOperation::GetLeastConstantLeft() const {
   HInstruction* most_constant_right = GetConstantRight();
   if (most_constant_right == nullptr) {
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 1a24cb5..0993a18 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -1634,7 +1634,7 @@
 
   // Try to statically evaluate `operation` and return a HConstant
   // containing the result of this evaluation.  If `operation` cannot
-  // be evaluated as a constant, return nullptr.
+  // be evaluated as a constant, return null.
   HConstant* TryStaticEvaluation() const;
 
   // Apply this operation to `x`.
@@ -1702,7 +1702,7 @@
 
   // Try to statically evaluate `operation` and return a HConstant
   // containing the result of this evaluation.  If `operation` cannot
-  // be evaluated as a constant, return nullptr.
+  // be evaluated as a constant, return null.
   HConstant* TryStaticEvaluation() const;
 
   // Apply this operation to `x` and `y`.
@@ -1710,11 +1710,11 @@
   virtual int64_t Evaluate(int64_t x, int64_t y) const = 0;
 
   // Returns an input that can legally be used as the right input and is
-  // constant, or nullptr.
+  // constant, or null.
   HConstant* GetConstantRight() const;
 
   // If `GetConstantRight()` returns one of the input, this returns the other
-  // one. Otherwise it returns nullptr.
+  // one. Otherwise it returns null.
   HInstruction* GetLeastConstantLeft() const;
 
   DECLARE_INSTRUCTION(BinaryOperation);
diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
index 03f5545..fe70d3a 100644
--- a/compiler/optimizing/ssa_liveness_analysis.h
+++ b/compiler/optimizing/ssa_liveness_analysis.h
@@ -333,7 +333,8 @@
     }
     if (after_loop == nullptr) {
       // Uses are only in the loop.
-      first_range_ = last_range_ = range_search_start_ = new (allocator_) LiveRange(start, end, nullptr);
+      first_range_ = last_range_ = range_search_start_ =
+          new (allocator_) LiveRange(start, end, nullptr);
     } else if (after_loop->GetStart() <= end) {
       first_range_ = range_search_start_ = after_loop;
       // There are uses after the loop.
@@ -596,7 +597,7 @@
         previous->next_ = nullptr;
         new_interval->first_range_ = current;
         if (range_search_start_ != nullptr && range_search_start_->GetEnd() >= current->GetEnd()) {
-          // Search start point is inside `new_interval`. Change it to nullptr
+          // Search start point is inside `new_interval`. Change it to null
           // (i.e. the end of the interval) in the original interval.
           range_search_start_ = nullptr;
         }
@@ -863,7 +864,7 @@
         defined_by_(defined_by) {}
 
   // Searches for a LiveRange that either covers the given position or is the
-  // first next LiveRange. Returns nullptr if no such LiveRange exists. Ranges
+  // first next LiveRange. Returns null if no such LiveRange exists. Ranges
   // known to end before `position` can be skipped with `search_start`.
   LiveRange* FindRangeAtOrAfter(size_t position, LiveRange* search_start) const {
     if (kIsDebugBuild) {