Completely merge the implementation details of DomTree and PostDomTree.

Also, add a FIXME for a bug in PostDomTree calculation I noticed while writing this,


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42593 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/DominatorInternals.h

@@ -208,6 +208,93 @@ void Link(DominatorTreeBase& DT, typename GraphT::NodeType* V,
 #endif
 }
 
+template<class NodeT>
+void Calculate(DominatorTreeBase& DT, Function& F) {
+  // Step #1: Number blocks in depth-first order and initialize variables used
+  // in later stages of the algorithm.
+  unsigned N = 0;
+  for (unsigned i = 0, e = DT.Roots.size(); i != e; ++i)
+    N = DFSPass<GraphTraits<NodeT> >(DT, DT.Roots[i], N);
+
+  for (unsigned i = N; i >= 2; --i) {
+    typename GraphTraits<NodeT>::NodeType* W = DT.Vertex[i];
+    DominatorTree::InfoRec &WInfo = DT.Info[W];
+
+    // Step #2: Calculate the semidominators of all vertices
+    for (typename GraphTraits<Inverse<NodeT> >::ChildIteratorType CI =
+         GraphTraits<Inverse<NodeT> >::child_begin(W),
+         E = GraphTraits<Inverse<NodeT> >::child_end(W); CI != E; ++CI)
+      if (DT.Info.count(*CI)) {  // Only if this predecessor is reachable!
+        unsigned SemiU = DT.Info[Eval<GraphTraits<NodeT> >(DT, *CI)].Semi;
+        if (SemiU < WInfo.Semi)
+          WInfo.Semi = SemiU;
+      }
+
+    DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
+
+    typename GraphTraits<NodeT>::NodeType* WParent = WInfo.Parent;
+    Link<GraphTraits<NodeT> >(DT, WParent, W, WInfo);
+
+    // Step #3: Implicitly define the immediate dominator of vertices
+    std::vector<typename GraphTraits<NodeT>::NodeType*> &WParentBucket =
+                                                        DT.Info[WParent].Bucket;
+    while (!WParentBucket.empty()) {
+      typename GraphTraits<NodeT>::NodeType* V = WParentBucket.back();
+      WParentBucket.pop_back();
+      typename GraphTraits<NodeT>::NodeType* U =
+                                               Eval<GraphTraits<NodeT> >(DT, V);
+      DT.IDoms[V] = DT.Info[U].Semi < DT.Info[V].Semi ? U : WParent;
+    }
+  }
+
+  // Step #4: Explicitly define the immediate dominator of each vertex
+  for (unsigned i = 2; i <= N; ++i) {
+    typename GraphTraits<NodeT>::NodeType* W = DT.Vertex[i];
+    typename GraphTraits<NodeT>::NodeType*& WIDom = DT.IDoms[W];
+    if (WIDom != DT.Vertex[DT.Info[W].Semi])
+      WIDom = DT.IDoms[WIDom];
+  }
+  
+  if (DT.Roots.empty()) return;
+  
+  // Add a node for the root.  This node might be the actual root, if there is
+  // one exit block, or it may be the virtual exit (denoted by (BasicBlock *)0)
+  // which postdominates all real exits if there are multiple exit blocks.
+  typename GraphTraits<NodeT>::NodeType* Root = DT.Roots.size() == 1 ? DT.Roots[0]
+                                                                     : 0;
+  DT.DomTreeNodes[Root] = DT.RootNode = new DomTreeNode(Root, 0);
+  
+  // Loop over all of the reachable blocks in the function...
+  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
+    if (typename GraphTraits<NodeT>::NodeType* ImmDom = DT.getIDom(I)) {
+      // Reachable block.
+      DomTreeNode *BBNode = DT.DomTreeNodes[I];
+      if (BBNode) continue;  // Haven't calculated this node yet?
+
+      // Get or calculate the node for the immediate dominator
+      DomTreeNode *IDomNode = DT.getNodeForBlock(ImmDom);
+
+      // Add a new tree node for this BasicBlock, and link it as a child of
+      // IDomNode
+      DomTreeNode *C = new DomTreeNode(I, IDomNode);
+      DT.DomTreeNodes[I] = IDomNode->addChild(C);
+    }
+  
+  // Free temporary memory used to construct idom's
+  DT.IDoms.clear();
+  DT.Info.clear();
+  std::vector<typename GraphTraits<NodeT>::NodeType*>().swap(DT.Vertex);
+  
+  // FIXME: This does not work on PostDomTrees.  It seems likely that this is
+  // due to an error in the algorithm for post-dominators.  This really should
+  // be investigated and fixed at some point.
+  // DT.updateDFSNumbers();
+
+  // Start out with the DFS numbers being invalid.  Let them be computed if
+  // demanded.
+  DT.DFSInfoValid = false;
+}
+
 }
 
 #endif

include/llvm/Analysis/Dominators.h

@@ -289,6 +289,9 @@ protected:
                                                  typename GraphT::NodeType* V,
                                                  unsigned N);
   
+  template<class NodeT> friend void Calculate(DominatorTreeBase& DT,
+                                              Function& F);
+  
   /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
   /// dominator tree in dfs order.
   void updateDFSNumbers();
@@ -325,9 +328,6 @@ public:
   /// BB is split and now it has one successor. Update dominator tree to
   /// reflect this change.
   void splitBlock(BasicBlock *BB);
-
-private:
-  friend void DTcalculate(DominatorTree& DT, Function& F);
 };
 
 //===-------------------------------------

include/llvm/Analysis/PostDominators.h

@@ -32,8 +32,6 @@ struct PostDominatorTree : public DominatorTreeBase {
   virtual void getAnalysisUsage(AnalysisUsage &AU) const {
     AU.setPreservesAll();
   }
-private:
-  friend void PDTcalculate(PostDominatorTree& PDT, Function &F);
 };
 
 

lib/Analysis/PostDominatorCalculation.h

@@ -1,99 +0,0 @@
-//==- PostDominatorCalculation.h - Post-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.
-//
-//===----------------------------------------------------------------------===//
-//
-// PostDominatorTree calculation implementation.
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_ANALYSIS_POST_DOMINATOR_CALCULATION_H
-#define LLVM_ANALYSIS_POST_DOMINATOR_CALCULATION_H
-
-#include "llvm/Analysis/PostDominators.h"
-#include "llvm/Analysis/DominatorInternals.h"
-
-namespace llvm {
-
-void PDTcalculate(PostDominatorTree& PDT, Function &F) {
-  // Step #1: Number blocks in depth-first order and initialize variables used
-  // in later stages of the algorithm.
-  unsigned N = 0;
-  for (unsigned i = 0, e = PDT.Roots.size(); i != e; ++i)
-    N = DFSPass<GraphTraits<Inverse<BasicBlock*> > >(PDT, PDT.Roots[i], N);
-  
-  for (unsigned i = N; i >= 2; --i) {
-    BasicBlock *W = PDT.Vertex[i];
-    PostDominatorTree::InfoRec &WInfo = PDT.Info[W];
-    
-    // Step #2: Calculate the semidominators of all vertices
-    for (succ_iterator SI = succ_begin(W), SE = succ_end(W); SI != SE; ++SI)
-      if (PDT.Info.count(*SI)) {  // Only if this predecessor is reachable!
-        unsigned SemiU =
-             PDT.Info[Eval<GraphTraits<Inverse<BasicBlock*> > >(PDT, *SI)].Semi;
-        if (SemiU < WInfo.Semi)
-          WInfo.Semi = SemiU;
-      }
-        
-    PDT.Info[PDT.Vertex[WInfo.Semi]].Bucket.push_back(W);
-    
-    BasicBlock *WParent = WInfo.Parent;
-    Link<GraphTraits<Inverse<BasicBlock*> > >(PDT, WParent, W, WInfo);
-    
-    // Step #3: Implicitly define the immediate dominator of vertices
-    std::vector<BasicBlock*> &WParentBucket = PDT.Info[WParent].Bucket;
-    while (!WParentBucket.empty()) {
-      BasicBlock *V = WParentBucket.back();
-      WParentBucket.pop_back();
-      BasicBlock *U = Eval<GraphTraits<Inverse<BasicBlock*> > >(PDT, V);
-      PDT.IDoms[V] = PDT.Info[U].Semi < PDT.Info[V].Semi ? U : WParent;
-    }
-  }
-  
-  // Step #4: Explicitly define the immediate dominator of each vertex
-  for (unsigned i = 2; i <= N; ++i) {
-    BasicBlock *W = PDT.Vertex[i];
-    BasicBlock *&WIDom = PDT.IDoms[W];
-    if (WIDom != PDT.Vertex[PDT.Info[W].Semi])
-      WIDom = PDT.IDoms[WIDom];
-  }
-  
-  if (PDT.Roots.empty()) return;
-
-  // Add a node for the root.  This node might be the actual root, if there is
-  // one exit block, or it may be the virtual exit (denoted by (BasicBlock *)0)
-  // which postdominates all real exits if there are multiple exit blocks.
-  BasicBlock *Root = PDT.Roots.size() == 1 ? PDT.Roots[0] : 0;
-  PDT.DomTreeNodes[Root] = PDT.RootNode = new DomTreeNode(Root, 0);
-  
-  // Loop over all of the reachable blocks in the function...
-  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
-    if (BasicBlock *ImmPostDom = PDT.getIDom(I)) {  // Reachable block.
-      DomTreeNode *&BBNode = PDT.DomTreeNodes[I];
-      if (!BBNode) {  // Haven't calculated this node yet?
-                      // Get or calculate the node for the immediate dominator
-        DomTreeNode *IPDomNode = PDT.getNodeForBlock(ImmPostDom);
-        
-        // Add a new tree node for this BasicBlock, and link it as a child of
-        // IDomNode
-        DomTreeNode *C = new DomTreeNode(I, IPDomNode);
-        PDT.DomTreeNodes[I] = C;
-        BBNode = IPDomNode->addChild(C);
-      }
-    }
-
-  // Free temporary memory used to construct idom's
-  PDT.IDoms.clear();
-  PDT.Info.clear();
-  std::vector<BasicBlock*>().swap(PDT.Vertex);
-
-  // Start out with the DFS numbers being invalid.  Let them be computed if
-  // demanded.
-  PDT.DFSInfoValid = false;
-}
-
-}
-#endif

lib/Analysis/PostDominators.cpp

@@ -16,7 +16,7 @@
 #include "llvm/Support/CFG.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SetOperations.h"
-#include "PostDominatorCalculation.h"
+#include "llvm/Analysis/DominatorInternals.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
@@ -47,7 +47,7 @@ bool PostDominatorTree::runOnFunction(Function &F) {
   
   Vertex.push_back(0);
     
-  PDTcalculate(*this, F);
+  Calculate<Inverse<BasicBlock*> >(*this, F);
   return false;
 }
 

lib/VMCore/DominatorCalculation.h

@@ -1,106 +0,0 @@
-//==- DominatorCalculation.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.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_VMCORE_DOMINATOR_CALCULATION_H
-#define LLVM_VMCORE_DOMINATOR_CALCULATION_H
-
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/DominatorInternals.h"
-
-//===----------------------------------------------------------------------===//
-//
-// DominatorTree construction - This pass constructs immediate dominator
-// information for a flow-graph based on the algorithm described in this
-// document:
-//
-//   A Fast Algorithm for Finding Dominators in a Flowgraph
-//   T. Lengauer & R. Tarjan, ACM TOPLAS July 1979, pgs 121-141.
-//
-// This implements both the O(n*ack(n)) and the O(n*log(n)) versions of EVAL and
-// LINK, but it turns out that the theoretically slower O(n*log(n))
-// implementation is actually faster than the "efficient" algorithm (even for
-// large CFGs) because the constant overheads are substantially smaller.  The
-// lower-complexity version can be enabled with the following #define:
-//
-#define BALANCE_IDOM_TREE 0
-//
-//===----------------------------------------------------------------------===//
-
-namespace llvm {
-  
-void DTcalculate(DominatorTree& DT, Function &F) {
-  BasicBlock* Root = DT.Roots[0];
-
-  // Add a node for the root...
-  DT.DomTreeNodes[Root] = DT.RootNode = new DomTreeNode(Root, 0);
-
-  // Step #1: Number blocks in depth-first order and initialize variables used
-  // in later stages of the algorithm.
-  unsigned N = DFSPass<GraphTraits<BasicBlock*> >(DT, Root, 0);
-
-  for (unsigned i = N; i >= 2; --i) {
-    BasicBlock *W = DT.Vertex[i];
-    DominatorTree::InfoRec &WInfo = DT.Info[W];
-
-    // Step #2: Calculate the semidominators of all vertices
-    for (pred_iterator PI = pred_begin(W), E = pred_end(W); PI != E; ++PI)
-      if (DT.Info.count(*PI)) {  // Only if this predecessor is reachable!
-        unsigned SemiU = DT.Info[Eval<GraphTraits<BasicBlock*> >(DT, *PI)].Semi;
-        if (SemiU < WInfo.Semi)
-          WInfo.Semi = SemiU;
-      }
-
-    DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
-
-    BasicBlock *WParent = WInfo.Parent;
-    Link<GraphTraits<BasicBlock*> >(DT, WParent, W, WInfo);
-
-    // Step #3: Implicitly define the immediate dominator of vertices
-    std::vector<BasicBlock*> &WParentBucket = DT.Info[WParent].Bucket;
-    while (!WParentBucket.empty()) {
-      BasicBlock *V = WParentBucket.back();
-      WParentBucket.pop_back();
-      BasicBlock *U = Eval<GraphTraits<BasicBlock*> >(DT, V);
-      DT.IDoms[V] = DT.Info[U].Semi < DT.Info[V].Semi ? U : WParent;
-    }
-  }
-
-  // Step #4: Explicitly define the immediate dominator of each vertex
-  for (unsigned i = 2; i <= N; ++i) {
-    BasicBlock *W = DT.Vertex[i];
-    BasicBlock *&WIDom = DT.IDoms[W];
-    if (WIDom != DT.Vertex[DT.Info[W].Semi])
-      WIDom = DT.IDoms[WIDom];
-  }
-
-  // Loop over all of the reachable blocks in the function...
-  for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
-    if (BasicBlock *ImmDom = DT.getIDom(I)) {  // Reachable block.
-      DomTreeNode *BBNode = DT.DomTreeNodes[I];
-      if (BBNode) continue;  // Haven't calculated this node yet?
-
-      // Get or calculate the node for the immediate dominator
-      DomTreeNode *IDomNode = DT.getNodeForBlock(ImmDom);
-
-      // Add a new tree node for this BasicBlock, and link it as a child of
-      // IDomNode
-      DomTreeNode *C = new DomTreeNode(I, IDomNode);
-      DT.DomTreeNodes[I] = IDomNode->addChild(C);
-    }
-
-  // Free temporary memory used to construct idom's
-  DT.Info.clear();
-  DT.IDoms.clear();
-  std::vector<BasicBlock*>().swap(DT.Vertex);
-
-  DT.updateDFSNumbers();
-}
-
-}
-#endif

lib/VMCore/Dominators.cpp

@@ -21,9 +21,9 @@
 #include "llvm/ADT/SetOperations.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/DominatorInternals.h"
 #include "llvm/Instructions.h"
 #include "llvm/Support/Streams.h"
-#include "DominatorCalculation.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -357,7 +357,10 @@ bool DominatorTree::runOnFunction(Function &F) {
   DomTreeNodes[&F.getEntryBlock()] = 0;
   Vertex.push_back(0);
   
-  DTcalculate(*this, F);
+  Calculate<BasicBlock*>(*this, F);
+  
+  updateDFSNumbers();
+  
   return false;
 }