Convert DFSPass into a templated friend function, in preparation for making it common to DomTree and PostDomTree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42420 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 91 insertions, 1 deletions

diff --git a/include/llvm/Analysis/DominatorInternals.h b/include/llvm/Analysis/DominatorInternals.h
new file mode 100644
index 0000000..66ac2b7
--- /dev/null
+++ b/include/llvm/Analysis/DominatorInternals.h
@@ -0,0 +1,89 @@
+//=== llvm/Analysis/DominatorInternals.h - Dominator Calculation -*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Owen Anderson and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines shared implementation details of dominator and
+// postdominator calculation.  This file SHOULD NOT BE INCLUDED outside
+// of the dominator and postdominator implementation files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_DOMINATOR_INTERNALS_H
+#define LLVM_ANALYSIS_DOMINATOR_INTERNALS_H
+
+#include "llvm/Analysis/Dominators.h"
+
+namespace llvm {
+
+template<class GraphT>
+unsigned DFSPass(DominatorTree& DT, typename GraphT::NodeType* V, unsigned N) {
+  // This is more understandable as a recursive algorithm, but we can't use the
+  // recursive algorithm due to stack depth issues.  Keep it here for
+  // documentation purposes.
+#if 0
+  InfoRec &VInfo = DT.Info[DT.Roots[i]];
+  VInfo.Semi = ++N;
+  VInfo.Label = V;
+
+  Vertex.push_back(V);        // Vertex[n] = V;
+  //Info[V].Ancestor = 0;     // Ancestor[n] = 0
+  //Info[V].Child = 0;        // Child[v] = 0
+  VInfo.Size = 1;             // Size[v] = 1
+
+  for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) {
+    InfoRec &SuccVInfo = DT.Info[*SI];
+    if (SuccVInfo.Semi == 0) {
+      SuccVInfo.Parent = V;
+      N = DTDFSPass(DT, *SI, N);
+    }
+  }
+#else
+  std::vector<std::pair<typename GraphT::NodeType*,
+                        typename GraphT::ChildIteratorType> > Worklist;
+  Worklist.push_back(std::make_pair(V, GraphT::child_begin(V)));
+  while (!Worklist.empty()) {
+    typename GraphT::NodeType* BB = Worklist.back().first;
+    typename GraphT::ChildIteratorType NextSucc = Worklist.back().second;
+
+    // First time we visited this BB?
+    if (NextSucc == GraphT::child_begin(BB)) {
+      DominatorTree::InfoRec &BBInfo = DT.Info[BB];
+      BBInfo.Semi = ++N;
+      BBInfo.Label = BB;
+
+      DT.Vertex.push_back(BB);       // Vertex[n] = V;
+      //BBInfo[V].Ancestor = 0;   // Ancestor[n] = 0
+      //BBInfo[V].Child = 0;      // Child[v] = 0
+      BBInfo.Size = 1;            // Size[v] = 1
+    }
+    
+    // If we are done with this block, remove it from the worklist.
+    if (NextSucc == GraphT::child_end(BB)) {
+      Worklist.pop_back();
+      continue;
+    }
+
+    // Increment the successor number for the next time we get to it.
+    ++Worklist.back().second;
+    
+    // Visit the successor next, if it isn't already visited.
+    typename GraphT::NodeType* Succ = *NextSucc;
+
+    DominatorTree::InfoRec &SuccVInfo = DT.Info[Succ];
+    if (SuccVInfo.Semi == 0) {
+      SuccVInfo.Parent = BB;
+      Worklist.push_back(std::make_pair(Succ, GraphT::child_begin(Succ)));
+    }
+  }
+#endif
+    return N;
+}
+
+}
+
+#endif
\ No newline at end of file
diff --git a/include/llvm/Analysis/Dominators.h b/include/llvm/Analysis/Dominators.h
index b9c85b5..e8ed92c 100644
--- a/include/llvm/Analysis/Dominators.h
+++ b/include/llvm/Analysis/Dominators.h
@@ -320,7 +320,8 @@ public:
 private:
   friend void DTcalculate(DominatorTree& DT, Function& F);
   
-  unsigned DFSPass(BasicBlock *V, unsigned N);
+  template<class GraphT> friend
+  unsigned DFSPass(DominatorTree& DT, typename GraphT::NodeType* V, unsigned N);
 };
 
 //===-------------------------------------