X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FDominators.cpp;h=c55f0e4a5141f4246ef217dcb663e568e0e74156;hb=287d11191f8470add8deaad90e2c40a953a4c4f5;hp=aad6e1cb386ba3d96b9c4968c98d9fa7f998861f;hpb=eb5230c4f98bd94c019bc2faed9432ca892e2f11;p=oota-llvm.git diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp index aad6e1cb386..c55f0e4a514 100644 --- a/lib/VMCore/Dominators.cpp +++ b/lib/VMCore/Dominators.cpp @@ -1,72 +1,77 @@ -//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=// +//===- Dominators.cpp - Dominator Calculation -----------------------------===// // -// This file provides a simple class to calculate the dominator set of a method. +// 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/UnifyMethodExitNodes.h" -#include "llvm/Method.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 //===----------------------------------------------------------------------===// -AnalysisID cfg::DominatorSet::ID(AnalysisID::create()); -AnalysisID cfg::DominatorSet::PostDomID(AnalysisID::create()); +static RegisterAnalysis +A("domset", "Dominator Set Construction", true); -bool cfg::DominatorSet::runOnMethod(Method *M) { - Doms.clear(); // Reset from the last time we were run... - - if (isPostDominator()) - calcPostDominatorSet(M); - else - calcForwardDominatorSet(M); - return false; +// dominates - Return true if A dominates B. This performs the special checks +// necessary 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; } -// calcForwardDominatorSet - This method calculates the forward dominator sets -// for the specified method. -// -void cfg::DominatorSet::calcForwardDominatorSet(Method *M) { - Root = M->getEntryNode(); - assert(Root->pred_begin() == Root->pred_end() && - "Root node has predecessors in method!"); - +void DominatorSet::calculateDominatorsFromBlock(BasicBlock *RootBB) { bool Changed; + Doms[RootBB].insert(RootBB); // Root always dominates itself... do { Changed = false; DomSetType WorkingSet; - df_iterator It = df_begin(M), End = df_end(M); + df_iterator It = df_begin(RootBB), End = df_end(RootBB); for ( ; It != End; ++It) { - const BasicBlock *BB = *It; - BasicBlock::pred_const_iterator PI = BB->pred_begin(), - PEnd = BB->pred_end(); + 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 + // Loop until we get to a predecessor that has had its 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. + // traversing the graph in DFO and have handled start nodes specially, + // except when there are unreachable blocks. // - 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); - } + while (PI != PEnd && Doms[*PI].empty()) ++PI; + if (PI != PEnd) { // Not unreachable code case? + WorkingSet = Doms[*PI]; + + // Intersect all of the predecessor sets + for (++PI; PI != PEnd; ++PI) { + DomSetType &PredSet = Doms[*PI]; + if (PredSet.size()) + set_intersect(WorkingSet, PredSet); + } + } + } else { + assert(BB == Root && "We got into unreachable code somehow!"); } WorkingSet.insert(BB); // A block always dominates itself DomSetType &BBSet = Doms[BB]; if (BBSet != WorkingSet) { + //assert(WorkingSet.size() > BBSet.size() && "Must only grow sets!"); BBSet.swap(WorkingSet); // Constant time operation! Changed = true; // The sets changed. } @@ -75,91 +80,70 @@ void cfg::DominatorSet::calcForwardDominatorSet(Method *M) { } while (Changed); } -// Postdominator set constructor. This ctor converts the specified method to -// only have a single exit node (return stmt), then calculates the post -// dominance sets for the method. + + +// runOnFunction - This method calculates the forward dominator sets for the +// specified function. // -void cfg::DominatorSet::calcPostDominatorSet(Method *M) { - // 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 method left. - // Get it. - // - Root = getAnalysis().getExitNode(); +bool DominatorSet::runOnFunction(Function &F) { + Root = &F.getEntryNode(); + assert(pred_begin(Root) == pred_end(Root) && + "Root node has predecessors in function!"); + recalculate(); + return false; +} - if (Root == 0) { // No exit node for the method? Postdomsets are all empty - for (Method::const_iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) - Doms[*MI] = DomSetType(); - return; - } +void DominatorSet::recalculate() { + Doms.clear(); // Reset from the last time we were run... - bool Changed; - do { - Changed = false; + // Calculate dominator sets for the reachable basic blocks... + calculateDominatorsFromBlock(Root); - set Visited; - DomSetType WorkingSet; - idf_iterator It = idf_begin(Root), End = idf_end(Root); - for ( ; It != End; ++It) { - const BasicBlock *BB = *It; - BasicBlock::succ_const_iterator PI = BB->succ_begin(), - PEnd = BB->succ_end(); - 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); + + // Loop through the function, ensuring that every basic block has at least an + // empty set of nodes. This is important for the case when there is + // unreachable blocks. + Function *F = Root->getParent(); + for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) Doms[I]; } -// getAnalysisUsageInfo - This obviously provides a dominator set, but it also -// uses the UnifyMethodExitNodes pass if building post-dominators -// -void cfg::DominatorSet::getAnalysisUsageInfo(Pass::AnalysisSet &Requires, - Pass::AnalysisSet &Destroyed, - Pass::AnalysisSet &Provided) { - if (isPostDominator()) { - Provided.push_back(PostDomID); - Requires.push_back(UnifyMethodExitNodes::ID); - } else { - Provided.push_back(ID); - } + +static std::ostream &operator<<(std::ostream &o, + const std::set &BBs) { + for (std::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: "; + WriteAsOperand(o, I->first, false); + o << "\n-------------------------------\n" << I->second << "\n"; + } +} //===----------------------------------------------------------------------===// // ImmediateDominators Implementation //===----------------------------------------------------------------------===// -AnalysisID cfg::ImmediateDominators::ID(AnalysisID::create()); -AnalysisID cfg::ImmediateDominators::PostDomID(AnalysisID::create()); +static RegisterAnalysis +C("idom", "Immediate Dominators Construction", true); // calcIDoms - Calculate the immediate dominator mapping, given a set of // dominators for every basic block. -void cfg::ImmediateDominators::calcIDoms(const DominatorSet &DS) { +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) { - const BasicBlock *BB = DI->first; + BasicBlock *BB = DI->first; const DominatorSet::DomSetType &Dominators = DI->second; unsigned DomSetSize = Dominators.size(); if (DomSetSize == 1) continue; // Root node... IDom = null @@ -187,157 +171,135 @@ void cfg::ImmediateDominators::calcIDoms(const DominatorSet &DS) { } } +void ImmediateDominatorsBase::print(std::ostream &o) const { + for (const_iterator I = begin(), E = end(); I != E; ++I) { + o << "=============================--------------------------------\n" + << "\nImmediate Dominator For Basic Block:"; + WriteAsOperand(o, I->first, false); + o << " is:"; + WriteAsOperand(o, I->second, false); + o << "\n"; + } +} + //===----------------------------------------------------------------------===// // DominatorTree Implementation //===----------------------------------------------------------------------===// -AnalysisID cfg::DominatorTree::ID(AnalysisID::create()); -AnalysisID cfg::DominatorTree::PostDomID(AnalysisID::create()); +static RegisterAnalysis +E("domtree", "Dominator Tree Construction", true); -// DominatorTree::reset - Free all of the tree node memory. +// DominatorTreeBase::reset - Free all of the tree node memory. // -void cfg::DominatorTree::reset() { +void DominatorTreeBase::reset() { for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) delete I->second; Nodes.clear(); } +void DominatorTreeBase::Node2::setIDom(Node2 *NewIDom) { + assert(IDom && "No immediate dominator?"); + if (IDom != NewIDom) { + std::vector::iterator I = + std::find(IDom->Children.begin(), IDom->Children.end(), this); + assert(I != IDom->Children.end() && + "Not in immediate dominator children set!"); + // I am no longer your child... + IDom->Children.erase(I); + + // Switch to new dominator + IDom = NewIDom; + IDom->Children.push_back(this); + } +} + -#if 0 -// Given immediate dominators, we can also calculate the dominator tree -cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms) - : DominatorBase(IDoms.getRoot()) { - const Method *M = Root->getParent(); +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(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! + 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... // - 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)); + 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; + } } } } -#endif -void cfg::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) { - const 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 - // method. - // - 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) { - const 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 method. - // - 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() + << "\n------------------------------------------\n"; +} + +static void PrintDomTree(const DominatorTreeBase::Node *N, std::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 //===----------------------------------------------------------------------===// -AnalysisID cfg::DominanceFrontier::ID(AnalysisID::create()); -AnalysisID cfg::DominanceFrontier::PostDomID(AnalysisID::create()); +static RegisterAnalysis +G("domfrontier", "Dominance Frontier Construction", true); -const cfg::DominanceFrontier::DomSetType & -cfg::DominanceFrontier::calcDomFrontier(const DominatorTree &DT, - const DominatorTree::Node *Node) { +const DominanceFrontier::DomSetType & +DominanceFrontier::calculate(const DominatorTree &DT, + const DominatorTree::Node *Node) { // Loop over CFG successors to calculate DFlocal[Node] - const BasicBlock *BB = Node->getNode(); + BasicBlock *BB = Node->getNode(); DomSetType &S = Frontiers[BB]; // The new set to fill in... - for (BasicBlock::succ_const_iterator SI = BB->succ_begin(), - SE = BB->succ_end(); SI != SE; ++SI) { + 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); @@ -350,7 +312,7 @@ cfg::DominanceFrontier::calcDomFrontier(const DominatorTree &DT, for (DominatorTree::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) { @@ -362,36 +324,11 @@ cfg::DominanceFrontier::calcDomFrontier(const DominatorTree &DT, return S; } -const cfg::DominanceFrontier::DomSetType & -cfg::DominanceFrontier::calcPostDomFrontier(const DominatorTree &DT, - const DominatorTree::Node *Node) { - // Loop over CFG successors to calculate DFlocal[Node] - const BasicBlock *BB = Node->getNode(); - DomSetType &S = Frontiers[BB]; // The new set to fill in... - if (!Root) return S; - - for (BasicBlock::pred_const_iterator SI = BB->pred_begin(), - SE = BB->pred_end(); SI != SE; ++SI) { - // Does Node immediately dominate this predeccessor? - if (DT[*SI]->getIDom() != Node) - S.insert(*SI); +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"; } - - // 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; }