X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FPostDominators.cpp;h=6be8f3dd2319d66cfc9ce316494a76b2bbe542eb;hb=706e61ead9b7913098ff3fbf729263a36e01f1b9;hp=30d170b6698da43bdf5cbd1128e28457ed071c57;hpb=1b7f7dc4b45a900fae2e9b062d588a995935727a;p=oota-llvm.git diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp index 30d170b6698..6be8f3dd231 100644 --- a/lib/Analysis/PostDominators.cpp +++ b/lib/Analysis/PostDominators.cpp @@ -1,288 +1,133 @@ -//===- 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/Transforms/UnifyFunctionExitNodes.h" -#include "llvm/Function.h" +#include "llvm/Analysis/PostDominators.h" +#include "llvm/iTerminators.h" #include "llvm/Support/CFG.h" #include "Support/DepthFirstIterator.h" -#include "Support/STLExtras.h" #include "Support/SetOperations.h" -#include -using std::set; //===----------------------------------------------------------------------===// -// DominatorSet Implementation +// PostDominatorSet Implementation //===----------------------------------------------------------------------===// -AnalysisID DominatorSet::ID(AnalysisID::create()); -AnalysisID DominatorSet::PostDomID(AnalysisID::create()); +static RegisterAnalysis +B("postdomset", "Post-Dominator Set Construction", true); -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... - if (isPostDominator()) - calcPostDominatorSet(F); - else - calcForwardDominatorSet(F); - return false; -} + // Scan the function looking for the root nodes of the post-dominance + // relationships. These blocks end with return and unwind instructions. + // While we are iterating over the function, we also initialize all of the + // domsets to empty. + Roots.clear(); + for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) { + Doms[I]; // Initialize to empty + + if (isa(I->getTerminator()) || + isa(I->getTerminator())) + Roots.push_back(I); + } + // If there are no exit nodes for the function, postdomsets are all empty. + // This can happen if the function just contains an infinite loop, for + // example. + if (Roots.empty()) return false; -// calcForwardDominatorSet - This method calculates the forward dominator sets -// for the specified function. -// -void DominatorSet::calcForwardDominatorSet(Function *M) { - Root = M->getEntryNode(); - assert(pred_begin(Root) == pred_end(Root) && - "Root node has predecessors in function!"); + // If we have more than one root, we insert an artificial "null" exit, which + // has "virtual edges" to each of the real exit nodes. + if (Roots.size() > 1) + Doms[0].insert(0); bool Changed; do { Changed = false; + std::set Visited; DomSetType WorkingSet; - df_iterator It = df_begin(M), End = df_end(M); - 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); - } - } + for (unsigned i = 0, e = Roots.size(); i != e; ++i) + for (idf_iterator It = idf_begin(Roots[i]), + E = idf_end(Roots[i]); It != E; ++It) { + BasicBlock *BB = *It; + succ_iterator SI = succ_begin(BB), SE = succ_end(BB); + if (SI != SE) { // Is there SOME successor? + // 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[*SI].size() == 0) ++SI; + WorkingSet = Doms[*SI]; + + for (++SI; SI != SE; ++SI) { // Intersect all of the successor sets + DomSetType &SuccSet = Doms[*SI]; + if (SuccSet.size()) + set_intersect(WorkingSet, SuccSet); + } + } else { + // If this node has no successors, it must be one of the root nodes. + // We will already take care of the notion that the node + // post-dominates itself. The only thing we have to add is that if + // there are multiple root nodes, we want to insert a special "null" + // exit node which dominates the roots as well. + if (Roots.size() > 1) + WorkingSet.insert(0); + } - 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.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 } - WorkingSet.clear(); // Clear out the set for next iteration - } } while (Changed); + return false; } -// Postdominator set constructor. This ctor converts the specified function to -// only have a single exit node (return stmt), then calculates the post -// dominance sets for the function. -// -void DominatorSet::calcPostDominatorSet(Function *F) { - // 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().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; - } - - bool Changed; - do { - Changed = false; - - set Visited; - DomSetType WorkingSet; - idf_iterator 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); -} - -// getAnalysisUsage - This obviously provides a dominator set, but it also -// uses the UnifyFunctionExitNodes pass if building post-dominators -// -void DominatorSet::getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesAll(); - if (isPostDominator()) { - AU.addProvided(PostDomID); - AU.addRequired(UnifyFunctionExitNodes::ID); - } else { - AU.addProvided(ID); - } -} - - //===----------------------------------------------------------------------===// -// ImmediateDominators Implementation +// ImmediatePostDominators Implementation //===----------------------------------------------------------------------===// -AnalysisID ImmediateDominators::ID(AnalysisID::create()); -AnalysisID ImmediateDominators::PostDomID(AnalysisID::create()); - -// calcIDoms - Calculate the immediate dominator mapping, given a set of -// dominators for every basic block. -void ImmediateDominators::calcIDoms(const DominatorSet &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; - } - } - } -} - +static RegisterAnalysis +D("postidom", "Immediate Post-Dominators Construction", true); //===----------------------------------------------------------------------===// -// DominatorTree Implementation +// PostDominatorTree Implementation //===----------------------------------------------------------------------===// -AnalysisID DominatorTree::ID(AnalysisID::create()); -AnalysisID DominatorTree::PostDomID(AnalysisID::create()); - -// DominatorTree::reset - Free all of the tree node memory. -// -void DominatorTree::reset() { - for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) - delete I->second; - Nodes.clear(); -} +static RegisterAnalysis +F("postdomtree", "Post-Dominator Tree Construction", true); +void PostDominatorTree::calculate(const PostDominatorSet &DS) { + if (Roots.empty()) return; + BasicBlock *Root = Roots.size() == 1 ? Roots[0] : 0; -#if 0 -// Given immediate dominators, we can also calculate the dominator tree -DominatorTree::DominatorTree(const ImmediateDominators &IDoms) - : DominatorBase(IDoms.getRoot()) { - const Function *M = Root->getParent(); - - Nodes[Root] = new Node(Root, 0); // Add a node for the root... + Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the root... // Iterate over all nodes in depth first order... - for (df_iterator I = df_begin(M), E = df_end(M); I!=E; ++I) { - const BasicBlock *BB = *I, *IDom = IDoms[*I]; - - if (IDom != 0) { // Ignore the root node and other nasty nodes - // We know that the immediate dominator should already have a node, - // because we are traversing the CFG in depth first order! - // - assert(Nodes[IDom] && "No node for IDOM?"); - Node *IDomNode = Nodes[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)); - } - } -} -#endif - -void DominatorTree::calculate(const DominatorSet &DS) { - Nodes[Root] = new Node(Root, 0); // Add a node for the root... - - if (!isPostDominator()) { - // Iterate over all nodes in depth first order... - for (df_iterator I = df_begin(Root), E = df_end(Root); - I != E; ++I) { + for (unsigned i = 0, e = Roots.size(); i != e; ++i) + for (idf_iterator I = idf_begin(Roots[i]), + E = idf_end(Roots[i]); 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; - } - } - } - } else if (Root) { - // Iterate over all nodes in depth first order... - for (idf_iterator 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 - + + // If we have already computed the immediate dominator for this node, + // don't revisit. This can happen due to nodes reachable from multiple + // roots, but which the idf_iterator doesn't know about. + if (Nodes.find(BB) != Nodes.end()) continue; + // 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 @@ -295,61 +140,59 @@ void DominatorTree::calculate(const DominatorSet &DS) { 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?"); + // 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; - } + // 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; + } } } - } } - - //===----------------------------------------------------------------------===// -// DominanceFrontier Implementation +// PostDominanceFrontier Implementation //===----------------------------------------------------------------------===// -AnalysisID DominanceFrontier::ID(AnalysisID::create()); -AnalysisID DominanceFrontier::PostDomID(AnalysisID::create()); +static RegisterAnalysis +H("postdomfrontier", "Post-Dominance Frontier Construction", true); const DominanceFrontier::DomSetType & -DominanceFrontier::calcDomFrontier(const DominatorTree &DT, - const DominatorTree::Node *Node) { +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 (getRoots().empty()) return S; - 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); - } + if (BB) + 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 (DominatorTree::Node::const_iterator NI = Node->begin(), NE = Node->end(); - NI != NE; ++NI) { + for (PostDominatorTree::Node::const_iterator + NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) { DominatorTree::Node *IDominee = *NI; - const DomSetType &ChildDF = calcDomFrontier(DT, IDominee); + const DomSetType &ChildDF = calculate(DT, IDominee); DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end(); for (; CDFI != CDFE; ++CDFI) { @@ -361,36 +204,6 @@ DominanceFrontier::calcDomFrontier(const DominatorTree &DT, return S; } -const DominanceFrontier::DomSetType & -DominanceFrontier::calcPostDomFrontier(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... - 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 (DominatorTree::Node::const_iterator NI = Node->begin(), NE = Node->end(); - NI != NE; ++NI) { - DominatorTree::Node *IDominee = *NI; - const DomSetType &ChildDF = calcPostDomFrontier(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; +// stub - a dummy function to make linking work ok. +void PostDominanceFrontier::stub() { }