X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FPostDominators.cpp;h=f027949793f853e16c07c11d5839ce00f1635ce7;hb=c53544af06acf3fba1788613a364f1f40317869e;hp=e4eb2c1119e3b09437ff0beac0686daa3e5828f4;hpb=fc514f40a63126bbda9404c717890f8dd6cbbcad;p=oota-llvm.git diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp index e4eb2c1119e..f027949793f 100644 --- a/lib/Analysis/PostDominators.cpp +++ b/lib/Analysis/PostDominators.cpp @@ -1,85 +1,29 @@ -//===- 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 "Support/DepthFirstIterator.h" -#include "Support/STLExtras.h" #include "Support/SetOperations.h" -#include using std::set; //===----------------------------------------------------------------------===// -// DominatorSet Implementation +// PostDominatorSet Implementation //===----------------------------------------------------------------------===// -AnalysisID DominatorSet::ID(AnalysisID::create(), true); -AnalysisID DominatorSet::PostDomID(AnalysisID::create(), true); +static RegisterAnalysis +B("postdomset", "Post-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; -} - - -// calcForwardDominatorSet - This method calculates the forward dominator sets -// for the specified function. +// 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. // -void DominatorSet::calcForwardDominatorSet(Function *M) { - Root = M->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(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); - } - } - - 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); -} - -// 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) { +bool PostDominatorSet::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. @@ -87,9 +31,9 @@ void DominatorSet::calcPostDominatorSet(Function *F) { 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; + for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) + Doms[FI] = DomSetType(); + return false; } bool Changed; @@ -115,6 +59,18 @@ void DominatorSet::calcPostDominatorSet(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 @@ -126,154 +82,35 @@ void DominatorSet::calcPostDominatorSet(Function *F) { WorkingSet.clear(); // Clear out the set for next iteration } } while (Changed); + return false; } -// getAnalysisUsage - This obviously provides a dominator set, but it also -// uses the UnifyFunctionExitNodes pass if building post-dominators +// getAnalysisUsage - This obviously provides a post-dominator set, but it also +// requires the UnifyFunctionExitNodes pass. // -void DominatorSet::getAnalysisUsage(AnalysisUsage &AU) const { +void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); - if (isPostDominator()) { - AU.addProvided(PostDomID); - AU.addRequired(UnifyFunctionExitNodes::ID); - } else { - AU.addProvided(ID); - } + AU.addRequired(); } - //===----------------------------------------------------------------------===// -// ImmediateDominators Implementation +// ImmediatePostDominators Implementation //===----------------------------------------------------------------------===// -AnalysisID ImmediateDominators::ID(AnalysisID::create(), true); -AnalysisID ImmediateDominators::PostDomID(AnalysisID::create(), true); - -// 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(), true); -AnalysisID DominatorTree::PostDomID(AnalysisID::create(), true); - -// 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(); -} - - -#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... - - // 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 +static RegisterAnalysis +F("postdomtree", "Post-Dominator Tree Construction", true); -void DominatorTree::calculate(const DominatorSet &DS) { +void PostDominatorTree::calculate(const PostDominatorSet &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) { + if (Root) { // Iterate over all nodes in depth first order... for (idf_iterator I = idf_begin(Root), E = idf_end(Root); I != E; ++I) { @@ -318,51 +155,16 @@ void DominatorTree::calculate(const DominatorSet &DS) { } } - - //===----------------------------------------------------------------------===// -// DominanceFrontier Implementation +// PostDominanceFrontier Implementation //===----------------------------------------------------------------------===// -AnalysisID DominanceFrontier::ID(AnalysisID::create(), true); -AnalysisID DominanceFrontier::PostDomID(AnalysisID::create(), true); - -const DominanceFrontier::DomSetType & -DominanceFrontier::calcDomFrontier(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 = calcDomFrontier(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; -} +static RegisterAnalysis +H("postdomfrontier", "Post-Dominance Frontier Construction", true); const DominanceFrontier::DomSetType & -DominanceFrontier::calcPostDomFrontier(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... @@ -379,10 +181,10 @@ DominanceFrontier::calcPostDomFrontier(const DominatorTree &DT, // 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 = calcPostDomFrontier(DT, IDominee); + const DomSetType &ChildDF = calculate(DT, IDominee); DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end(); for (; CDFI != CDFE; ++CDFI) { @@ -393,3 +195,7 @@ DominanceFrontier::calcPostDomFrontier(const DominatorTree &DT, return S; } + +// stub - a dummy function to make linking work ok. +void PostDominanceFrontier::stub() { +}