X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FPostDominators.cpp;h=f027949793f853e16c07c11d5839ce00f1635ce7;hb=bb05f1ee9317fa984519cd8d5079a444d5d5df2c;hp=8dd731a5de17704418ea7478f8c0914140b5457c;hpb=17689dfe241702cbbbd29cf1e4e4229444f3e9f3;p=oota-llvm.git diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp index 8dd731a5de1..f027949793f 100644 --- a/lib/Analysis/PostDominators.cpp +++ b/lib/Analysis/PostDominators.cpp @@ -1,93 +1,23 @@ -//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=// +//===- PostDominators.cpp - Post-Dominator Calculation --------------------===// // -// This file provides a simple class to calculate the dominator set of a -// function. +// This file implements the post-dominator construction algorithms. // //===----------------------------------------------------------------------===// -#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/PostDominators.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 using std::set; //===----------------------------------------------------------------------===// -// DominatorSet Implementation +// PostDominatorSet Implementation //===----------------------------------------------------------------------===// -static RegisterAnalysis -A("domset", "Dominator Set Construction", true); static RegisterAnalysis 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. -// -bool DominatorSetBase::dominates(Instruction *A, Instruction *B) const { - BasicBlock *BBA = A->getParent(), *BBB = B->getParent(); - if (BBA != BBB) return dominates(BBA, BBB); - - // Loop through the basic block until we find A or B. - BasicBlock::iterator I = BBA->begin(); - for (; &*I != A && &*I != B; ++I) /*empty*/; - - // A dominates B if it is found first in the basic block... - return &*I == A; -} - -// runOnFunction - This method calculates the forward dominator sets for the -// specified function. -// -bool DominatorSet::runOnFunction(Function &F) { - Doms.clear(); // Reset from the last time we were run... - Root = &F.getEntryNode(); - assert(pred_begin(Root) == pred_end(Root) && - "Root node has predecessors in function!"); - - bool Changed; - do { - Changed = false; - - DomSetType WorkingSet; - df_iterator It = df_begin(&F), End = df_end(&F); - for ( ; It != End; ++It) { - BasicBlock *BB = *It; - pred_iterator PI = pred_begin(BB), PEnd = pred_end(BB); - if (PI != PEnd) { // Is there SOME predecessor? - // Loop until we get to a predecessor 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 predecessor 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; -} - - // 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. @@ -129,6 +59,18 @@ bool PostDominatorSet::runOnFunction(Function &F) { if (PredSet.size()) set_intersect(WorkingSet, PredSet); } + } else if (BB != Root) { + // If this isn't the root basic block and it has no successors, it must + // be an non-returning block. Fib a bit by saying that the root node + // postdominates this unreachable node. This isn't exactly true, + // because there is no path from this node to the root node, but it is + // sorta true because any paths to the exit node would have to go + // through this node. + // + // This allows for postdominator properties to be built for code that + // doesn't return in a reasonable manner. + // + WorkingSet = Doms[Root]; } WorkingSet.insert(BB); // A block always dominates itself @@ -148,149 +90,23 @@ bool PostDominatorSet::runOnFunction(Function &F) { // void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); - AU.addRequired(UnifyFunctionExitNodes::ID); -} - -static ostream &operator<<(ostream &o, const set &BBs) { - for (set::const_iterator I = BBs.begin(), E = BBs.end(); - I != E; ++I) { - o << " "; - WriteAsOperand(o, *I, false); - o << "\n"; - } - return o; -} - -void DominatorSetBase::print(std::ostream &o) const { - for (const_iterator I = begin(), E = end(); I != E; ++I) - o << "=============================--------------------------------\n" - << "\nDominator Set For Basic Block\n" << I->first - << "-------------------------------\n" << I->second << "\n"; + AU.addRequired(); } //===----------------------------------------------------------------------===// -// ImmediateDominators Implementation +// ImmediatePostDominators Implementation //===----------------------------------------------------------------------===// -static RegisterAnalysis -C("idom", "Immediate Dominators Construction", true); static RegisterAnalysis 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. -void ImmediateDominatorsBase::calcIDoms(const DominatorSetBase &DS) { - // Loop over all of the nodes that have dominators... figuring out the IDOM - // for each node... - // - for (DominatorSet::const_iterator DI = DS.begin(), DEnd = DS.end(); - DI != DEnd; ++DI) { - BasicBlock *BB = DI->first; - const DominatorSet::DomSetType &Dominators = DI->second; - 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! - // - 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) { - IDoms[BB] = *I; - break; - } - } - } -} - -void ImmediateDominatorsBase::print(ostream &o) const { - for (const_iterator I = begin(), E = end(); I != E; ++I) - o << "=============================--------------------------------\n" - << "\nImmediate Dominator For Basic Block\n" << *I->first - << "is: \n" << *I->second << "\n"; -} - - //===----------------------------------------------------------------------===// -// DominatorTree Implementation +// PostDominatorTree Implementation //===----------------------------------------------------------------------===// -static RegisterAnalysis -E("domtree", "Dominator Tree Construction", true); static RegisterAnalysis F("postdomtree", "Post-Dominator Tree Construction", true); -AnalysisID DominatorTree::ID = E; -AnalysisID PostDominatorTree::ID = F; - -// DominatorTreeBase::reset - Free all of the tree node memory. -// -void DominatorTreeBase::reset() { - for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) - delete I->second; - Nodes.clear(); -} - - -void DominatorTree::calculate(const DominatorSet &DS) { - Nodes[Root] = new Node(Root, 0); // Add a node for the root... - - // Iterate over all nodes in depth first order... - for (df_iterator I = df_begin(Root), E = df_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; - } - } - } -} - - void PostDominatorTree::calculate(const PostDominatorSet &DS) { Nodes[Root] = new Node(Root, 0); // Add a node for the root... @@ -339,72 +155,13 @@ void PostDominatorTree::calculate(const PostDominatorSet &DS) { } } -static ostream &operator<<(ostream &o, const DominatorTreeBase::Node *Node) { - return o << Node->getNode() - << "\n------------------------------------------\n"; -} - -static void PrintDomTree(const DominatorTreeBase::Node *N, ostream &o, - unsigned Lev) { - o << "Level #" << Lev << ": " << N; - for (DominatorTreeBase::Node::const_iterator I = N->begin(), E = N->end(); - I != E; ++I) { - PrintDomTree(*I, o, Lev+1); - } -} - -void DominatorTreeBase::print(std::ostream &o) const { - o << "=============================--------------------------------\n" - << "Inorder Dominator Tree:\n"; - PrintDomTree(Nodes.find(getRoot())->second, o, 1); -} - - //===----------------------------------------------------------------------===// -// DominanceFrontier Implementation +// PostDominanceFrontier Implementation //===----------------------------------------------------------------------===// -static RegisterAnalysis -G("domfrontier", "Dominance Frontier Construction", true); static RegisterAnalysis H("postdomfrontier", "Post-Dominance Frontier Construction", true); -AnalysisID DominanceFrontier::ID = G; -AnalysisID PostDominanceFrontier::ID = H; - -const DominanceFrontier::DomSetType & -DominanceFrontier::calculate(const DominatorTree &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... - - for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); - SI != SE; ++SI) { - // Does Node immediately dominate this successor? - 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 (DominatorTree::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; -} - const DominanceFrontier::DomSetType & PostDominanceFrontier::calculate(const PostDominatorTree &DT, const DominatorTree::Node *Node) { @@ -439,11 +196,6 @@ PostDominanceFrontier::calculate(const PostDominatorTree &DT, return S; } -void DominanceFrontierBase::print(std::ostream &o) const { - for (const_iterator I = begin(), E = end(); I != E; ++I) { - o << "=============================--------------------------------\n" - << "\nDominance Frontier For Basic Block\n"; - WriteAsOperand(o, I->first, false); - o << " is: \n" << I->second << "\n"; - } +// stub - a dummy function to make linking work ok. +void PostDominanceFrontier::stub() { }