X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FDominators.cpp;h=cd0825c128ab41789d26b5089f385236eb960adf;hb=f90a0e4bd7c99788d85655e9f52c63a3a58f7431;hp=e4eb2c1119e3b09437ff0beac0686daa3e5828f4;hpb=fc514f40a63126bbda9404c717890f8dd6cbbcad;p=oota-llvm.git diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp index e4eb2c1119e..cd0825c128a 100644 --- a/lib/VMCore/Dominators.cpp +++ b/lib/VMCore/Dominators.cpp @@ -1,51 +1,50 @@ -//===- 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 using std::set; //===----------------------------------------------------------------------===// // DominatorSet Implementation //===----------------------------------------------------------------------===// -AnalysisID DominatorSet::ID(AnalysisID::create(), true); -AnalysisID DominatorSet::PostDomID(AnalysisID::create(), true); +static RegisterAnalysis +A("domset", "Dominator Set Construction", true); -bool DominatorSet::runOnFunction(Function *F) { - Doms.clear(); // Reset from the last time we were run... - - if (isPostDominator()) - calcPostDominatorSet(F); - else - calcForwardDominatorSet(F); - return false; +// 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; } -// 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!"); - +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) { BasicBlock *BB = *It; pred_iterator PI = pred_begin(BB), PEnd = pred_end(BB); @@ -54,7 +53,7 @@ void DominatorSet::calcForwardDominatorSet(Function *M) { // 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; + while (Doms[*PI].empty()) ++PI; WorkingSet = Doms[*PI]; for (++PI; PI != PEnd; ++PI) { // Intersect all of the predecessor sets @@ -75,83 +74,62 @@ void DominatorSet::calcForwardDominatorSet(Function *M) { } while (Changed); } -// 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; +// 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!"); - 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]; + // Calculate dominator sets for the reachable basic blocks... + calculateDominatorsFromBlock(Root); - 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 + // Every basic block in the function should at least dominate themselves, and + // thus every basic block should have an entry in Doms. The one case where we + // miss this is when a basic block is unreachable. To get these we now do an + // extra pass over the function, calculating dominator information for + // unreachable blocks. + // + for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) + if (Doms[I].empty()) { + calculateDominatorsFromBlock(I); } - } while (Changed); + + return false; } -// 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); - } + +static std::ostream &operator<<(std::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"; +} //===----------------------------------------------------------------------===// // ImmediateDominators Implementation //===----------------------------------------------------------------------===// -AnalysisID ImmediateDominators::ID(AnalysisID::create(), true); -AnalysisID ImmediateDominators::PostDomID(AnalysisID::create(), true); +static RegisterAnalysis +C("idom", "Immediate Dominators Construction", true); // calcIDoms - Calculate the immediate dominator mapping, given a set of // dominators for every basic block. -void 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... // @@ -185,151 +163,108 @@ void 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\n" << *I->first + << "is: \n" << *I->second << "\n"; +} + //===----------------------------------------------------------------------===// // DominatorTree Implementation //===----------------------------------------------------------------------===// -AnalysisID DominatorTree::ID(AnalysisID::create(), true); -AnalysisID DominatorTree::PostDomID(AnalysisID::create(), true); +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 DominatorTree::reset() { +void DominatorTreeBase::reset() { for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) delete I->second; Nodes.clear(); } -#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(); - +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 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) { - 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 - - // 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() + << "\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 DominanceFrontier::ID(AnalysisID::create(), true); -AnalysisID DominanceFrontier::PostDomID(AnalysisID::create(), true); +static RegisterAnalysis +G("domfrontier", "Dominance Frontier Construction", true); const DominanceFrontier::DomSetType & -DominanceFrontier::calcDomFrontier(const DominatorTree &DT, - const DominatorTree::Node *Node) { +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... @@ -348,7 +283,7 @@ 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) { @@ -360,36 +295,11 @@ 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); - } +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"; } - - return S; }