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DominanceFrontier::calculate().

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Avoid recursion, Use iterative algorithm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35225 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2007-03-20 21:25:31 +00:00
parent c01a53007a
commit cbdfb8a9d5
1 changed files with 77 additions and 22 deletions
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99
lib/VMCore/Dominators.cpp
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@ -46,6 +46,19 @@ using namespace llvm;
static RegisterPass<ImmediateDominators>
C("idom", "Immediate Dominators Construction", true);
namespace {
class DFCalculateWorkObject {
public:
DFCalculateWorkObject(BasicBlock *B, BasicBlock *P,
const DominatorTree::Node *N,
const DominatorTree::Node *PN)
: currentBB(B), parentBB(P), Node(N), parentNode(PN) {}
BasicBlock *currentBB;
BasicBlock *parentBB;
const DominatorTree::Node *Node;
const DominatorTree::Node *parentNode;
};
}
unsigned ImmediateDominators::DFSPass(BasicBlock *V, InfoRec &VInfo,
unsigned N) {
VInfo.Semi = ++N;
@ -439,34 +452,76 @@ G("domfrontier", "Dominance Frontier Construction", true);
const DominanceFrontier::DomSetType &
DominanceFrontier::calculate(const DominatorTree &DT,
const DominatorTree::Node *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
BasicBlock *BB = Node->getBlock();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
DomSetType *Result = NULL;
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);
}
std::vector<DFCalculateWorkObject *> workList;
std::set<BasicBlock *> visited;
// 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 = calculate(DT, IDominee);
DFCalculateWorkObject *W = new DFCalculateWorkObject(BB, NULL, Node, NULL);
workList.push_back(W);
do {
DFCalculateWorkObject *currentW = workList.back();
assert (currentW && "Missing work object.");
DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
for (; CDFI != CDFE; ++CDFI) {
if (!Node->properlyDominates(DT[*CDFI]))
S.insert(*CDFI);
BasicBlock *currentBB = currentW->currentBB;
BasicBlock *parentBB = currentW->parentBB;
const DominatorTree::Node *currentNode = currentW->Node;
const DominatorTree::Node *parentNode = currentW->parentNode;
assert (currentBB && "Invalid work object. Missing current Basic Block");
assert (currentNode && "Invalid work object. Missing current Node");
DomSetType &S = Frontiers[currentBB];
// Visit each block only once.
if (visited.count(currentBB) == 0) {
visited.insert(currentBB);
// Loop over CFG successors to calculate DFlocal[currentNode]
for (succ_iterator SI = succ_begin(currentBB), SE = succ_end(currentBB);
SI != SE; ++SI) {
// Does Node immediately dominate this successor?
if (DT[*SI]->getIDom() != currentNode)
S.insert(*SI);
}
}
}
return S;
// 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)
bool visitChild = false;
for (DominatorTree::Node::const_iterator NI = currentNode->begin(),
NE = currentNode->end(); NI != NE; ++NI) {
DominatorTree::Node *IDominee = *NI;
BasicBlock *childBB = IDominee->getBlock();
if (visited.count(childBB) == 0) {
DFCalculateWorkObject *newW =
new DFCalculateWorkObject(childBB, currentBB, IDominee, currentNode);
workList.push_back(newW);
visitChild = true;
}
}
// If all children are visited or there is any child then pop this block
// from the workList.
if (!visitChild) {
if (!parentBB) {
Result = &S;
break;
}
DomSetType::const_iterator CDFI = S.begin(), CDFE = S.end();
DomSetType &parentSet = Frontiers[parentBB];
for (; CDFI != CDFE; ++CDFI) {
if (!parentNode->properlyDominates(DT[*CDFI]))
parentSet.insert(*CDFI);
}
workList.pop_back();
}
} while (!workList.empty());
return *Result;
}
void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {