Split dominance calculation and post dominance calculation stuff

Dominance calculation goes to VMCore library to be used by Verifier.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3210 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 167 deletions

diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp
index 1aff600..eb57587 100644
--- a/lib/VMCore/Dominators.cpp
+++ b/lib/VMCore/Dominators.cpp
@@ -1,18 +1,17 @@
-//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=//
+//===- Dominators.cpp - Dominator Calculation -----------------------------===//
 //
-// This file provides a simple class to calculate the dominator set of a
-// function.
+// This file implements simple dominator construction algorithms for finding
+// forward dominators.  Postdominators are available in libanalysis, but are not
+// included in libvmcore, because it's not needed.  Forward dominators are
+// needed to support the Verifier pass.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/Dominators.h"
-#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Assembly/Writer.h"
 #include "Support/DepthFirstIterator.h"
-#include "Support/STLExtras.h"
 #include "Support/SetOperations.h"
-#include <algorithm>
 using std::set;
 
 //===----------------------------------------------------------------------===//
@@ -21,11 +20,7 @@ using std::set;
 
 static RegisterAnalysis<DominatorSet>
 A("domset", "Dominator Set Construction", true);
-static RegisterAnalysis<PostDominatorSet>
-B("postdomset", "Post-Dominator Set Construction", true);
-
 AnalysisID DominatorSet::ID = A;
-AnalysisID PostDominatorSet::ID = B;
 
 // dominates - Return true if A dominates B.  This performs the special checks
 // neccesary if A and B are in the same basic block.
@@ -88,69 +83,6 @@ bool DominatorSet::runOnFunction(Function &F) {
 }
 
 
-// Postdominator set construction.  This converts the specified function to only
-// have a single exit node (return stmt), then calculates the post dominance
-// sets for the function.
-//
-bool PostDominatorSet::runOnFunction(Function &F) {
-  Doms.clear();   // Reset from the last time we were run...
-  // Since we require that the unify all exit nodes pass has been run, we know
-  // that there can be at most one return instruction in the function left.
-  // Get it.
-  //
-  Root = getAnalysis<UnifyFunctionExitNodes>().getExitNode();
-
-  if (Root == 0) {  // No exit node for the function?  Postdomsets are all empty
-    for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
-      Doms[FI] = DomSetType();
-    return false;
-  }
-
-  bool Changed;
-  do {
-    Changed = false;
-
-    set<const BasicBlock*> Visited;
-    DomSetType WorkingSet;
-    idf_iterator<BasicBlock*> It = idf_begin(Root), End = idf_end(Root);
-    for ( ; It != End; ++It) {
-      BasicBlock *BB = *It;
-      succ_iterator PI = succ_begin(BB), PEnd = succ_end(BB);
-      if (PI != PEnd) {                // Is there SOME predecessor?
-	// Loop until we get to a successor that has had it's dom set filled
-	// in at least once.  We are guaranteed to have this because we are
-	// traversing the graph in DFO and have handled start nodes specially.
-	//
-	while (Doms[*PI].size() == 0) ++PI;
-	WorkingSet = Doms[*PI];
-
-	for (++PI; PI != PEnd; ++PI) { // Intersect all of the successor sets
-	  DomSetType &PredSet = Doms[*PI];
-	  if (PredSet.size())
-	    set_intersect(WorkingSet, PredSet);
-	}
-      }
-	
-      WorkingSet.insert(BB);           // A block always dominates itself
-      DomSetType &BBSet = Doms[BB];
-      if (BBSet != WorkingSet) {
-	BBSet.swap(WorkingSet);        // Constant time operation!
-	Changed = true;                // The sets changed.
-      }
-      WorkingSet.clear();              // Clear out the set for next iteration
-    }
-  } while (Changed);
-  return false;
-}
-
-// getAnalysisUsage - This obviously provides a post-dominator set, but it also
-// requires the UnifyFunctionExitNodes pass.
-//
-void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesAll();
-  AU.addRequired(UnifyFunctionExitNodes::ID);
-}
-
 static std::ostream &operator<<(std::ostream &o, const set<BasicBlock*> &BBs) {
   for (set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
        I != E; ++I) {
@@ -174,11 +106,7 @@ void DominatorSetBase::print(std::ostream &o) const {
 
 static RegisterAnalysis<ImmediateDominators>
 C("idom", "Immediate Dominators Construction", true);
-static RegisterAnalysis<ImmediatePostDominators>
-D("postidom", "Immediate Post-Dominators Construction", true);
-
 AnalysisID ImmediateDominators::ID = C;
-AnalysisID ImmediatePostDominators::ID = D;
 
 // calcIDoms - Calculate the immediate dominator mapping, given a set of
 // dominators for every basic block.
@@ -230,11 +158,7 @@ void ImmediateDominatorsBase::print(std::ostream &o) const {
 
 static RegisterAnalysis<DominatorTree>
 E("domtree", "Dominator Tree Construction", true);
-static RegisterAnalysis<PostDominatorTree>
-F("postdomtree", "Post-Dominator Tree Construction", true);
-
 AnalysisID DominatorTree::ID = E;
-AnalysisID PostDominatorTree::ID = F;
 
 // DominatorTreeBase::reset - Free all of the tree node memory.
 //
@@ -291,54 +215,6 @@ void DominatorTree::calculate(const DominatorSet &DS) {
 }
 
 
-void PostDominatorTree::calculate(const PostDominatorSet &DS) {
-  Nodes[Root] = new Node(Root, 0);   // Add a node for the root...
-
-  if (Root) {
-    // Iterate over all nodes in depth first order...
-    for (idf_iterator<BasicBlock*> I = idf_begin(Root), E = idf_end(Root);
-         I != E; ++I) {
-      BasicBlock *BB = *I;
-      const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
-      unsigned DomSetSize = Dominators.size();
-      if (DomSetSize == 1) continue;  // Root node... IDom = null
-      
-      // Loop over all dominators of this node.  This corresponds to looping
-      // over nodes in the dominator chain, looking for a node whose dominator
-      // set is equal to the current nodes, except that the current node does
-      // not exist in it.  This means that it is one level higher in the dom
-      // chain than the current node, and it is our idom!  We know that we have
-      // already added a DominatorTree node for our idom, because the idom must
-      // be a predecessor in the depth first order that we are iterating through
-      // the function.
-      //
-      DominatorSet::DomSetType::const_iterator I = Dominators.begin();
-      DominatorSet::DomSetType::const_iterator End = Dominators.end();
-      for (; I != End; ++I) {   // Iterate over dominators...
-	// All of our dominators should form a chain, where the number
-	// of elements in the dominator set indicates what level the
-	// node is at in the chain.  We want the node immediately
-	// above us, so it will have an identical dominator set,
-	// except that BB will not dominate it... therefore it's
-	// dominator set size will be one less than BB's...
-	//
-	if (DS.getDominators(*I).size() == DomSetSize - 1) {
-	  // We know that the immediate dominator should already have a node, 
-	  // because we are traversing the CFG in depth first order!
-	  //
-	  Node *IDomNode = Nodes[*I];
-	  assert(IDomNode && "No node for IDOM?");
-	  
-	  // Add a new tree node for this BasicBlock, and link it as a child of
-	  // IDomNode
-	  Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
-	  break;
-	}
-      }
-    }
-  }
-}
-
 static std::ostream &operator<<(std::ostream &o,
                                 const DominatorTreeBase::Node *Node) {
   return o << Node->getNode()
@@ -367,11 +243,7 @@ void DominatorTreeBase::print(std::ostream &o) const {
 
 static RegisterAnalysis<DominanceFrontier>
 G("domfrontier", "Dominance Frontier Construction", true);
-static RegisterAnalysis<PostDominanceFrontier>
-H("postdomfrontier", "Post-Dominance Frontier Construction", true);
-
 AnalysisID DominanceFrontier::ID = G;
-AnalysisID PostDominanceFrontier::ID = H;
 
 const DominanceFrontier::DomSetType &
 DominanceFrontier::calculate(const DominatorTree &DT, 
@@ -406,40 +278,6 @@ DominanceFrontier::calculate(const DominatorTree &DT,
   return S;
 }
 
-const DominanceFrontier::DomSetType &
-PostDominanceFrontier::calculate(const PostDominatorTree &DT, 
-                                 const DominatorTree::Node *Node) {
-  // Loop over CFG successors to calculate DFlocal[Node]
-  BasicBlock *BB = Node->getNode();
-  DomSetType &S = Frontiers[BB];       // The new set to fill in...
-  if (!Root) return S;
-
-  for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
-       SI != SE; ++SI) {
-    // Does Node immediately dominate this predeccessor?
-    if (DT[*SI]->getIDom() != Node)
-      S.insert(*SI);
-  }
-
-  // At this point, S is DFlocal.  Now we union in DFup's of our children...
-  // Loop through and visit the nodes that Node immediately dominates (Node's
-  // children in the IDomTree)
-  //
-  for (PostDominatorTree::Node::const_iterator
-         NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
-    DominatorTree::Node *IDominee = *NI;
-    const DomSetType &ChildDF = calculate(DT, IDominee);
-
-    DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
-    for (; CDFI != CDFE; ++CDFI) {
-      if (!Node->dominates(DT[*CDFI]))
-	S.insert(*CDFI);
-    }
-  }
-
-  return S;
-}
-
 void DominanceFrontierBase::print(std::ostream &o) const {
   for (const_iterator I = begin(), E = end(); I != E; ++I) {
     o << "=============================--------------------------------\n"