diff options
Diffstat (limited to 'lib/Analysis/PostDominators.cpp')
| -rw-r--r-- | lib/Analysis/PostDominators.cpp | 214 |
1 files changed, 173 insertions, 41 deletions
diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp index d6483423eb..c9e15f4a51 100644 --- a/lib/Analysis/PostDominators.cpp +++ b/lib/Analysis/PostDominators.cpp @@ -5,6 +5,7 @@ //===----------------------------------------------------------------------===// #include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/SimplifyCFG.h" // To get cfg::UnifyAllExitNodes #include "llvm/CFG.h" #include "llvm/Tools/STLExtras.h" #include <algorithm> @@ -26,6 +27,14 @@ void set_intersect(set<Ty> &S1, const set<Ty2> &S2) { } } +//===----------------------------------------------------------------------===// +// DominatorBase Implementation +//===----------------------------------------------------------------------===// + +bool cfg::DominatorBase::isPostDominator() const { + return Root != Root->getParent()->front(); +} + //===----------------------------------------------------------------------===// // DominatorSet Implementation @@ -34,8 +43,14 @@ void set_intersect(set<Ty> &S1, const set<Ty2> &S2) { // DominatorSet ctor - Build either the dominator set or the post-dominator // set for a method... // -cfg::DominatorSet::DominatorSet(const Method *M, bool PostDomSet) - : Root(M->front()) { +cfg::DominatorSet::DominatorSet(const Method *M) : DominatorBase(M->front()) { + calcForwardDominatorSet(M); +} + +// calcForwardDominatorSet - This method calculates the forward dominator sets +// for the specified method. +// +void cfg::DominatorSet::calcForwardDominatorSet(const Method *M) { assert(Root && M && "Can't build dominator set of null method!"); bool Changed; do { @@ -70,7 +85,53 @@ cfg::DominatorSet::DominatorSet(const Method *M, bool PostDomSet) WorkingSet.clear(); // Clear out the set for next iteration } } 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. +// +cfg::DominatorSet::DominatorSet(Method *M, bool PostDomSet) + : DominatorBase(M->front()) { + if (!PostDomSet) { calcForwardDominatorSet(M); return; } + + Root = cfg::UnifyAllExitNodes(M); + assert(Root && "TODO: Don't handle case where there are no exit nodes yet!"); + bool Changed; + do { + Changed = false; + + set<const BasicBlock*> Visited; + DomSetType WorkingSet; + idf_const_iterator It = idf_begin(Root), End = idf_end(Root); + for ( ; It != End; ++It) { + const BasicBlock *BB = *It; + succ_const_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); } @@ -128,8 +189,7 @@ cfg::DominatorTree::~DominatorTree() { cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms) - : Root(IDoms.getRoot()) { - assert(Root && Root->getParent() && "No method for IDoms?"); + : DominatorBase(IDoms.getRoot()) { const Method *M = Root->getParent(); Nodes[Root] = new Node(Root, 0); // Add a node for the root... @@ -153,47 +213,86 @@ cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms) } void cfg::DominatorTree::calculate(const DominatorSet &DS) { - Root = DS.getRoot(); - assert(Root && Root->getParent() && "No method for IDoms?"); - const Method *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_const_iterator I = df_begin(M), E = df_end(M); 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 (!isPostDominator()) { + // Iterate over all nodes in depth first order... + for (df_const_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. // - 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! + 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... // - Node *IDomNode = Nodes[*I]; - assert(Nodes[*I] && "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; + 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 { + // Iterate over all nodes in depth first order... + for (idf_const_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; + } } } } @@ -237,3 +336,36 @@ 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... + + for (pred_const_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 = 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; +} |