[llvm] r346349 - [MachineOutliner][NFC] Remove Parent field from SuffixTreeNode

[Jessica Paquette via llvm-commits]

Author: paquette
Date: Wed Nov  7 11:56:13 2018
New Revision: 346349

URL: http://llvm.org/viewvc/llvm-project?rev=346349&view=rev
Log:
[MachineOutliner][NFC] Remove Parent field from SuffixTreeNode

This is only used for calculating ConcatLen. This isn't necessary,
since it's easily derived from the traversal setting suffix indices.

Remove that. Rename CurrIdx to CurrNodeLen to better describe what's
going on.

Modified:
    llvm/trunk/lib/CodeGen/MachineOutliner.cpp

Modified: llvm/trunk/lib/CodeGen/MachineOutliner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineOutliner.cpp?rev=346349&r1=346348&r2=346349&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineOutliner.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineOutliner.cpp Wed Nov  7 11:56:13 2018
@@ -164,9 +164,6 @@ struct SuffixTreeNode {
   /// construction algorithm O(N^2) rather than O(N).
   SuffixTreeNode *Link = nullptr;
 
-  /// The parent of this node. Every node except for the root has a parent.
-  SuffixTreeNode *Parent = nullptr;
-
   /// The length of the string formed by concatenating the edge labels from the
   /// root to this node.
   unsigned ConcatLen = 0;
@@ -191,9 +188,8 @@ struct SuffixTreeNode {
     return *EndIdx - StartIdx + 1;
   }
 
-  SuffixTreeNode(unsigned StartIdx, unsigned *EndIdx, SuffixTreeNode *Link,
-                 SuffixTreeNode *Parent)
-      : StartIdx(StartIdx), EndIdx(EndIdx), Link(Link), Parent(Parent) {}
+  SuffixTreeNode(unsigned StartIdx, unsigned *EndIdx, SuffixTreeNode *Link)
+      : StartIdx(StartIdx), EndIdx(EndIdx), Link(Link) {}
 
   SuffixTreeNode() {}
 };
@@ -286,7 +282,7 @@ private:
     assert(StartIdx <= LeafEndIdx && "String can't start after it ends!");
 
     SuffixTreeNode *N = new (NodeAllocator.Allocate())
-        SuffixTreeNode(StartIdx, &LeafEndIdx, nullptr, &Parent);
+        SuffixTreeNode(StartIdx, &LeafEndIdx, nullptr);
     Parent.Children[Edge] = N;
 
     return N;
@@ -309,7 +305,7 @@ private:
 
     unsigned *E = new (InternalEndIdxAllocator) unsigned(EndIdx);
     SuffixTreeNode *N = new (NodeAllocator.Allocate())
-        SuffixTreeNode(StartIdx, E, Root, Parent);
+        SuffixTreeNode(StartIdx, E, Root);
     if (Parent)
       Parent->Children[Edge] = N;
 
@@ -320,33 +316,24 @@ private:
   /// respective suffixes.
   ///
   /// \param[in] CurrNode The node currently being visited.
-  /// \param CurrIdx The current index of the string being visited.
-  void setSuffixIndices(SuffixTreeNode &CurrNode, unsigned CurrIdx) {
+  /// \param CurrNodeLen The concatenation of all node sizes from the root to
+  /// this node. Used to produce suffix indices.
+  void setSuffixIndices(SuffixTreeNode &CurrNode, unsigned CurrNodeLen) {
 
     bool IsLeaf = CurrNode.Children.size() == 0 && !CurrNode.isRoot();
 
-    // Store the length of the concatenation of all strings from the root to
-    // this node.
-    if (!CurrNode.isRoot()) {
-      if (CurrNode.ConcatLen == 0)
-        CurrNode.ConcatLen = CurrNode.size();
-
-      if (CurrNode.Parent)
-        CurrNode.ConcatLen += CurrNode.Parent->ConcatLen;
-    }
-
+    // Store the concatenation of lengths down from the root.
+    CurrNode.ConcatLen = CurrNodeLen;
     // Traverse the tree depth-first.
     for (auto &ChildPair : CurrNode.Children) {
       assert(ChildPair.second && "Node had a null child!");
-      setSuffixIndices(*ChildPair.second, CurrIdx + ChildPair.second->size());
+      setSuffixIndices(*ChildPair.second,
+                       CurrNodeLen + ChildPair.second->size());
     }
 
-    // Is this node a leaf?
-    if (IsLeaf) {
-      // If yes, give it a suffix index and bump its parent's occurrence count.
-      CurrNode.SuffixIdx = Str.size() - CurrIdx;
-      assert(CurrNode.Parent && "CurrNode had no parent!");
-    }
+    // Is this node a leaf? If it is, give it a suffix index.
+    if (IsLeaf)
+      CurrNode.SuffixIdx = Str.size() - CurrNodeLen;
   }
 
   /// Construct the suffix tree for the prefix of the input ending at
@@ -451,7 +438,6 @@ private:
         // Make the old node a child of the split node and update its start
         // index. This is the node n from the diagram.
         NextNode->StartIdx += Active.Len;
-        NextNode->Parent = SplitNode;
         SplitNode->Children[Str[NextNode->StartIdx]] = NextNode;
 
         // SplitNode is an internal node, update the suffix link.