X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FDominators.cpp;h=cd0825c128ab41789d26b5089f385236eb960adf;hb=fa3068813b44e9d03d88fb2bda6ec09dbbf4d0ef;hp=9b35d16b9047fc01938a36b23bd36992cc001fed;hpb=1e43516dcf4aa152432447397334cd43744d63e1;p=oota-llvm.git diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp index 9b35d16b904..cd0825c128a 100644 --- a/lib/VMCore/Dominators.cpp +++ b/lib/VMCore/Dominators.cpp @@ -1,17 +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 using std::set; //===----------------------------------------------------------------------===// @@ -19,12 +19,7 @@ using std::set; //===----------------------------------------------------------------------===// static RegisterAnalysis -A("domset", "Dominator Set Construction"); -static RegisterAnalysis -B("postdomset", "Post-Dominator Set Construction"); - -AnalysisID DominatorSet::ID(AnalysisID::create(), true); -AnalysisID PostDominatorSet::ID(AnalysisID::create(), true); +A("domset", "Dominator Set Construction", true); // dominates - Return true if A dominates B. This performs the special checks // neccesary if A and B are in the same basic block. @@ -41,21 +36,15 @@ bool DominatorSetBase::dominates(Instruction *A, Instruction *B) const { 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!"); +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(&F), End = df_end(&F); + 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); @@ -64,7 +53,7 @@ bool DominatorSet::runOnFunction(Function &F) { // 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 @@ -83,86 +72,60 @@ bool DominatorSet::runOnFunction(Function &F) { 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. + +// runOnFunction - This method calculates the forward dominator sets for the +// specified function. // -bool PostDominatorSet::runOnFunction(Function &F) { +bool DominatorSet::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().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; + 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 post-dominator set, but it also -// requires the UnifyFunctionExitNodes pass. -// -void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesAll(); - AU.addProvided(ID); - AU.addRequired(UnifyFunctionExitNodes::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 //===----------------------------------------------------------------------===// static RegisterAnalysis -C("idom", "Immediate Dominators Construction"); -static RegisterAnalysis -D("postidom", "Immediate Post-Dominators Construction"); - -AnalysisID ImmediateDominators::ID(AnalysisID::create(), true); -AnalysisID ImmediatePostDominators::ID(AnalysisID::create(), true); +C("idom", "Immediate Dominators Construction", true); // calcIDoms - Calculate the immediate dominator mapping, given a set of // dominators for every basic block. @@ -200,18 +163,20 @@ void ImmediateDominatorsBase::calcIDoms(const DominatorSetBase &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 //===----------------------------------------------------------------------===// static RegisterAnalysis -E("domtree", "Dominator Tree Construction"); -static RegisterAnalysis -F("postdomtree", "Post-Dominator Tree Construction"); - -AnalysisID DominatorTree::ID(AnalysisID::create(), true); -AnalysisID PostDominatorTree::ID(AnalysisID::create(), true); +E("domtree", "Dominator Tree Construction", true); // DominatorTreeBase::reset - Free all of the tree node memory. // @@ -268,54 +233,26 @@ void DominatorTree::calculate(const DominatorSet &DS) { } -void PostDominatorTree::calculate(const PostDominatorSet &DS) { - Nodes[Root] = new Node(Root, 0); // Add a node for the root... +static std::ostream &operator<<(std::ostream &o, + const DominatorTreeBase::Node *Node) { + return o << Node->getNode() + << "\n------------------------------------------\n"; +} - 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 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); +} //===----------------------------------------------------------------------===// @@ -323,12 +260,7 @@ void PostDominatorTree::calculate(const PostDominatorSet &DS) { //===----------------------------------------------------------------------===// static RegisterAnalysis -G("domfrontier", "Dominance Frontier Construction"); -static RegisterAnalysis -H("postdomfrontier", "Post-Dominance Frontier Construction"); - -AnalysisID DominanceFrontier::ID(AnalysisID::create(), true); -AnalysisID PostDominanceFrontier::ID(AnalysisID::create(), true); +G("domfrontier", "Dominance Frontier Construction", true); const DominanceFrontier::DomSetType & DominanceFrontier::calculate(const DominatorTree &DT, @@ -363,36 +295,11 @@ 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); - } +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; }