#include "llvm/Assembly/Writer.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Instructions.h"
+#include "llvm/Support/Streams.h"
+#include "DominatorCalculation.h"
#include <algorithm>
using namespace llvm;
+namespace llvm {
+static std::ostream &operator<<(std::ostream &o,
+ const std::set<BasicBlock*> &BBs) {
+ for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
+ I != E; ++I)
+ if (*I)
+ WriteAsOperand(o, *I, false);
+ else
+ o << " <<exit node>>";
+ return o;
+}
+}
+
//===----------------------------------------------------------------------===//
-// ImmediateDominators Implementation
+// DominatorTree Implementation
//===----------------------------------------------------------------------===//
//
-// Immediate Dominators construction - This pass constructs immediate dominator
-// information for a flow-graph based on the algorithm described in this
-// document:
-//
-// A Fast Algorithm for Finding Dominators in a Flowgraph
-// T. Lengauer & R. Tarjan, ACM TOPLAS July 1979, pgs 121-141.
-//
-// This implements both the O(n*ack(n)) and the O(n*log(n)) versions of EVAL and
-// LINK, but it turns out that the theoretically slower O(n*log(n))
-// implementation is actually faster than the "efficient" algorithm (even for
-// large CFGs) because the constant overheads are substantially smaller. The
-// lower-complexity version can be enabled with the following #define:
-//
-#define BALANCE_IDOM_TREE 0
+// Provide public access to DominatorTree information. Implementation details
+// can be found in DominatorCalculation.h.
//
//===----------------------------------------------------------------------===//
-static RegisterAnalysis<ImmediateDominators>
-C("idom", "Immediate Dominators Construction", true);
-
-unsigned ImmediateDominators::DFSPass(BasicBlock *V, InfoRec &VInfo,
- unsigned N) {
- VInfo.Semi = ++N;
- VInfo.Label = V;
-
- Vertex.push_back(V); // Vertex[n] = V;
- //Info[V].Ancestor = 0; // Ancestor[n] = 0
- //Child[V] = 0; // Child[v] = 0
- VInfo.Size = 1; // Size[v] = 1
-
- for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) {
- InfoRec &SuccVInfo = Info[*SI];
- if (SuccVInfo.Semi == 0) {
- SuccVInfo.Parent = V;
- N = DFSPass(*SI, SuccVInfo, N);
- }
- }
- return N;
-}
-
-void ImmediateDominators::Compress(BasicBlock *V, InfoRec &VInfo) {
- BasicBlock *VAncestor = VInfo.Ancestor;
- InfoRec &VAInfo = Info[VAncestor];
- if (VAInfo.Ancestor == 0)
- return;
-
- Compress(VAncestor, VAInfo);
+char DominatorTree::ID = 0;
+static RegisterPass<DominatorTree>
+E("domtree", "Dominator Tree Construction", true);
- BasicBlock *VAncestorLabel = VAInfo.Label;
- BasicBlock *VLabel = VInfo.Label;
- if (Info[VAncestorLabel].Semi < Info[VLabel].Semi)
- VInfo.Label = VAncestorLabel;
+// NewBB is split and now it has one successor. Update dominator tree to
+// reflect this change.
+void DominatorTree::splitBlock(BasicBlock *NewBB) {
+ assert(NewBB->getTerminator()->getNumSuccessors() == 1
+ && "NewBB should have a single successor!");
+ BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
- VInfo.Ancestor = VAInfo.Ancestor;
-}
+ std::vector<BasicBlock*> PredBlocks;
+ for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
+ PI != PE; ++PI)
+ PredBlocks.push_back(*PI);
-BasicBlock *ImmediateDominators::Eval(BasicBlock *V) {
- InfoRec &VInfo = Info[V];
-#if !BALANCE_IDOM_TREE
- // Higher-complexity but faster implementation
- if (VInfo.Ancestor == 0)
- return V;
- Compress(V, VInfo);
- return VInfo.Label;
-#else
- // Lower-complexity but slower implementation
- if (VInfo.Ancestor == 0)
- return VInfo.Label;
- Compress(V, VInfo);
- BasicBlock *VLabel = VInfo.Label;
-
- BasicBlock *VAncestorLabel = Info[VInfo.Ancestor].Label;
- if (Info[VAncestorLabel].Semi >= Info[VLabel].Semi)
- return VLabel;
- else
- return VAncestorLabel;
-#endif
-}
+ assert(!PredBlocks.empty() && "No predblocks??");
-void ImmediateDominators::Link(BasicBlock *V, BasicBlock *W, InfoRec &WInfo){
-#if !BALANCE_IDOM_TREE
- // Higher-complexity but faster implementation
- WInfo.Ancestor = V;
-#else
- // Lower-complexity but slower implementation
- BasicBlock *WLabel = WInfo.Label;
- unsigned WLabelSemi = Info[WLabel].Semi;
- BasicBlock *S = W;
- InfoRec *SInfo = &Info[S];
-
- BasicBlock *SChild = SInfo->Child;
- InfoRec *SChildInfo = &Info[SChild];
-
- while (WLabelSemi < Info[SChildInfo->Label].Semi) {
- BasicBlock *SChildChild = SChildInfo->Child;
- if (SInfo->Size+Info[SChildChild].Size >= 2*SChildInfo->Size) {
- SChildInfo->Ancestor = S;
- SInfo->Child = SChild = SChildChild;
- SChildInfo = &Info[SChild];
- } else {
- SChildInfo->Size = SInfo->Size;
- S = SInfo->Ancestor = SChild;
- SInfo = SChildInfo;
- SChild = SChildChild;
- SChildInfo = &Info[SChild];
+ // The newly inserted basic block will dominate existing basic blocks iff the
+ // PredBlocks dominate all of the non-pred blocks. If all predblocks dominate
+ // the non-pred blocks, then they all must be the same block!
+ //
+ bool NewBBDominatesNewBBSucc = true;
+ {
+ BasicBlock *OnePred = PredBlocks[0];
+ unsigned i = 1, e = PredBlocks.size();
+ for (i = 1; !isReachableFromEntry(OnePred); ++i) {
+ assert(i != e && "Didn't find reachable pred?");
+ OnePred = PredBlocks[i];
}
- }
-
- InfoRec &VInfo = Info[V];
- SInfo->Label = WLabel;
-
- assert(V != W && "The optimization here will not work in this case!");
- unsigned WSize = WInfo.Size;
- unsigned VSize = (VInfo.Size += WSize);
-
- if (VSize < 2*WSize)
- std::swap(S, VInfo.Child);
+
+ for (; i != e; ++i)
+ if (PredBlocks[i] != OnePred && isReachableFromEntry(OnePred)) {
+ NewBBDominatesNewBBSucc = false;
+ break;
+ }
- while (S) {
- SInfo = &Info[S];
- SInfo->Ancestor = V;
- S = SInfo->Child;
+ if (NewBBDominatesNewBBSucc)
+ for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
+ PI != E; ++PI)
+ if (*PI != NewBB && !dominates(NewBBSucc, *PI)) {
+ NewBBDominatesNewBBSucc = false;
+ break;
+ }
}
-#endif
-}
-
-
-bool ImmediateDominators::runOnFunction(Function &F) {
- IDoms.clear(); // Reset from the last time we were run...
- BasicBlock *Root = &F.getEntryBlock();
- Roots.clear();
- Roots.push_back(Root);
-
- Vertex.push_back(0);
-
- // Step #1: Number blocks in depth-first order and initialize variables used
- // in later stages of the algorithm.
- unsigned N = 0;
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- N = DFSPass(Roots[i], Info[Roots[i]], 0);
-
- for (unsigned i = N; i >= 2; --i) {
- BasicBlock *W = Vertex[i];
- InfoRec &WInfo = Info[W];
-
- // Step #2: Calculate the semidominators of all vertices
- for (pred_iterator PI = pred_begin(W), E = pred_end(W); PI != E; ++PI)
- if (Info.count(*PI)) { // Only if this predecessor is reachable!
- unsigned SemiU = Info[Eval(*PI)].Semi;
- if (SemiU < WInfo.Semi)
- WInfo.Semi = SemiU;
+ // The other scenario where the new block can dominate its successors are when
+ // all predecessors of NewBBSucc that are not NewBB are dominated by NewBBSucc
+ // already.
+ if (!NewBBDominatesNewBBSucc) {
+ NewBBDominatesNewBBSucc = true;
+ for (pred_iterator PI = pred_begin(NewBBSucc), E = pred_end(NewBBSucc);
+ PI != E; ++PI)
+ if (*PI != NewBB && !dominates(NewBBSucc, *PI)) {
+ NewBBDominatesNewBBSucc = false;
+ break;
}
+ }
- Info[Vertex[WInfo.Semi]].Bucket.push_back(W);
-
- BasicBlock *WParent = WInfo.Parent;
- Link(WParent, W, WInfo);
-
- // Step #3: Implicitly define the immediate dominator of vertices
- std::vector<BasicBlock*> &WParentBucket = Info[WParent].Bucket;
- while (!WParentBucket.empty()) {
- BasicBlock *V = WParentBucket.back();
- WParentBucket.pop_back();
- BasicBlock *U = Eval(V);
- IDoms[V] = Info[U].Semi < Info[V].Semi ? U : WParent;
+ // Find NewBB's immediate dominator and create new dominator tree node for
+ // NewBB.
+ BasicBlock *NewBBIDom = 0;
+ unsigned i = 0;
+ for (i = 0; i < PredBlocks.size(); ++i)
+ if (isReachableFromEntry(PredBlocks[i])) {
+ NewBBIDom = PredBlocks[i];
+ break;
}
+ assert(i != PredBlocks.size() && "No reachable preds?");
+ for (i = i + 1; i < PredBlocks.size(); ++i) {
+ if (isReachableFromEntry(PredBlocks[i]))
+ NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
}
-
- // Step #4: Explicitly define the immediate dominator of each vertex
- for (unsigned i = 2; i <= N; ++i) {
- BasicBlock *W = Vertex[i];
- BasicBlock *&WIDom = IDoms[W];
- if (WIDom != Vertex[Info[W].Semi])
- WIDom = IDoms[WIDom];
+ assert(NewBBIDom && "No immediate dominator found??");
+
+ // Create the new dominator tree node... and set the idom of NewBB.
+ DomTreeNode *NewBBNode = addNewBlock(NewBB, NewBBIDom);
+
+ // If NewBB strictly dominates other blocks, then it is now the immediate
+ // dominator of NewBBSucc. Update the dominator tree as appropriate.
+ if (NewBBDominatesNewBBSucc) {
+ DomTreeNode *NewBBSuccNode = getNode(NewBBSucc);
+ changeImmediateDominator(NewBBSuccNode, NewBBNode);
}
-
- // Free temporary memory used to construct idom's
- Info.clear();
- std::vector<BasicBlock*>().swap(Vertex);
-
- return false;
}
-void ImmediateDominatorsBase::print(std::ostream &o, const Module* ) const {
- Function *F = getRoots()[0]->getParent();
- for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
- o << " Immediate Dominator For Basic Block:";
- WriteAsOperand(o, I, false);
- o << " is:";
- if (BasicBlock *ID = get(I))
- WriteAsOperand(o, ID, false);
- else
- o << " <<exit node>>";
- o << "\n";
+void DominatorTreeBase::updateDFSNumbers() {
+ unsigned DFSNum = 0;
+
+ SmallVector<std::pair<DomTreeNode*, DomTreeNode::iterator>, 32> WorkStack;
+
+ for (unsigned i = 0, e = Roots.size(); i != e; ++i) {
+ DomTreeNode *ThisRoot = getNode(Roots[i]);
+ WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
+ ThisRoot->DFSNumIn = DFSNum++;
+
+ while (!WorkStack.empty()) {
+ DomTreeNode *Node = WorkStack.back().first;
+ DomTreeNode::iterator ChildIt = WorkStack.back().second;
+
+ // If we visited all of the children of this node, "recurse" back up the
+ // stack setting the DFOutNum.
+ if (ChildIt == Node->end()) {
+ Node->DFSNumOut = DFSNum++;
+ WorkStack.pop_back();
+ } else {
+ // Otherwise, recursively visit this child.
+ DomTreeNode *Child = *ChildIt;
+ ++WorkStack.back().second;
+
+ WorkStack.push_back(std::make_pair(Child, Child->begin()));
+ Child->DFSNumIn = DFSNum++;
+ }
+ }
}
- o << "\n";
+
+ SlowQueries = 0;
+ DFSInfoValid = true;
}
+/// isReachableFromEntry - Return true if A is dominated by the entry
+/// block of the function containing it.
+const bool DominatorTreeBase::isReachableFromEntry(BasicBlock* A) {
+ assert (!isPostDominator()
+ && "This is not implemented for post dominators");
+ return dominates(&A->getParent()->getEntryBlock(), A);
+}
-
-//===----------------------------------------------------------------------===//
-// DominatorSet Implementation
-//===----------------------------------------------------------------------===//
-
-static RegisterAnalysis<DominatorSet>
-B("domset", "Dominator Set Construction", true);
-
-// dominates - Return true if A dominates B. This performs the special checks
-// necessary if A and B are in the same basic block.
-//
-bool DominatorSetBase::dominates(Instruction *A, Instruction *B) const {
+// dominates - Return true if A dominates B. THis performs the
+// special checks necessary if A and B are in the same basic block.
+bool DominatorTreeBase::dominates(Instruction *A, Instruction *B) {
BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
if (BBA != BBB) return dominates(BBA, BBB);
+
+ // It is not possible to determine dominance between two PHI nodes
+ // based on their ordering.
+ if (isa<PHINode>(A) && isa<PHINode>(B))
+ return false;
// 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;
+
+ if(!IsPostDominators) {
+ // A dominates B if it is found first in the basic block.
+ return &*I == A;
+ } else {
+ // A post-dominates B if B is found first in the basic block.
+ return &*I == B;
+ }
}
-
-// runOnFunction - This method calculates the forward dominator sets for the
-// specified function.
+// DominatorTreeBase::reset - Free all of the tree node memory.
//
-bool DominatorSet::runOnFunction(Function &F) {
- BasicBlock *Root = &F.getEntryBlock();
+void DominatorTreeBase::reset() {
+ for (DomTreeNodeMapType::iterator I = DomTreeNodes.begin(),
+ E = DomTreeNodes.end(); I != E; ++I)
+ delete I->second;
+ DomTreeNodes.clear();
+ IDoms.clear();
Roots.clear();
- Roots.push_back(Root);
- assert(pred_begin(Root) == pred_end(Root) &&
- "Root node has predecessors in function!");
-
- ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
- Doms.clear();
- if (Roots.empty()) return false;
-
- // Root nodes only dominate themselves.
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- Doms[Roots[i]].insert(Roots[i]);
-
- // Loop over all of the blocks in the function, calculating dominator sets for
- // each function.
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
- if (BasicBlock *IDom = ID[I]) { // Get idom if block is reachable
- DomSetType &DS = Doms[I];
- assert(DS.empty() && "Domset already filled in for this block?");
- DS.insert(I); // Blocks always dominate themselves
-
- // Insert all dominators into the set...
- while (IDom) {
- // If we have already computed the dominator sets for our immediate
- // dominator, just use it instead of walking all the way up to the root.
- DomSetType &IDS = Doms[IDom];
- if (!IDS.empty()) {
- DS.insert(IDS.begin(), IDS.end());
- break;
- } else {
- DS.insert(IDom);
- IDom = ID[IDom];
- }
- }
- } else {
- // Ensure that every basic block has at least an empty set of nodes. This
- // is important for the case when there is unreachable blocks.
- Doms[I];
- }
-
- return false;
+ Vertex.clear();
+ RootNode = 0;
}
-void DominatorSet::stub() {}
+DomTreeNode *DominatorTreeBase::getNodeForBlock(BasicBlock *BB) {
+ if (DomTreeNode *BBNode = DomTreeNodes[BB])
+ return BBNode;
-namespace llvm {
-static std::ostream &operator<<(std::ostream &o,
- const std::set<BasicBlock*> &BBs) {
- for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
- I != E; ++I)
- if (*I)
- WriteAsOperand(o, *I, false);
- else
- o << " <<exit node>>";
- return o;
-}
+ // Haven't calculated this node yet? Get or calculate the node for the
+ // immediate dominator.
+ BasicBlock *IDom = getIDom(BB);
+ DomTreeNode *IDomNode = getNodeForBlock(IDom);
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ DomTreeNode *C = new DomTreeNode(BB, IDomNode);
+ return DomTreeNodes[BB] = IDomNode->addChild(C);
}
-void DominatorSetBase::print(std::ostream &o, const Module* ) const {
- for (const_iterator I = begin(), E = end(); I != E; ++I) {
- o << " DomSet For BB: ";
- if (I->first)
- WriteAsOperand(o, I->first, false);
- else
- o << " <<exit node>>";
- o << " is:\t" << I->second << "\n";
+/// findNearestCommonDominator - Find nearest common dominator basic block
+/// for basic block A and B. If there is no such block then return NULL.
+BasicBlock *DominatorTreeBase::findNearestCommonDominator(BasicBlock *A,
+ BasicBlock *B) {
+
+ assert (!isPostDominator()
+ && "This is not implemented for post dominators");
+ assert (A->getParent() == B->getParent()
+ && "Two blocks are not in same function");
+
+ // If either A or B is a entry block then it is nearest common dominator.
+ BasicBlock &Entry = A->getParent()->getEntryBlock();
+ if (A == &Entry || B == &Entry)
+ return &Entry;
+
+ // If B dominates A then B is nearest common dominator.
+ if (dominates(B, A))
+ return B;
+
+ // If A dominates B then A is nearest common dominator.
+ if (dominates(A, B))
+ return A;
+
+ DomTreeNode *NodeA = getNode(A);
+ DomTreeNode *NodeB = getNode(B);
+
+ // Collect NodeA dominators set.
+ SmallPtrSet<DomTreeNode*, 16> NodeADoms;
+ NodeADoms.insert(NodeA);
+ DomTreeNode *IDomA = NodeA->getIDom();
+ while (IDomA) {
+ NodeADoms.insert(IDomA);
+ IDomA = IDomA->getIDom();
}
-}
-//===----------------------------------------------------------------------===//
-// DominatorTree Implementation
-//===----------------------------------------------------------------------===//
+ // Walk NodeB immediate dominators chain and find common dominator node.
+ DomTreeNode *IDomB = NodeB->getIDom();
+ while(IDomB) {
+ if (NodeADoms.count(IDomB) != 0)
+ return IDomB->getBlock();
-static RegisterAnalysis<DominatorTree>
-E("domtree", "Dominator Tree Construction", true);
+ IDomB = IDomB->getIDom();
+ }
-// DominatorTreeBase::reset - Free all of the tree node memory.
-//
-void DominatorTreeBase::reset() {
- for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I)
- delete I->second;
- Nodes.clear();
- RootNode = 0;
+ return NULL;
}
-void DominatorTreeBase::Node::setIDom(Node *NewIDom) {
+void DomTreeNode::setIDom(DomTreeNode *NewIDom) {
assert(IDom && "No immediate dominator?");
if (IDom != NewIDom) {
- std::vector<Node*>::iterator I =
+ std::vector<DomTreeNode*>::iterator I =
std::find(IDom->Children.begin(), IDom->Children.end(), this);
assert(I != IDom->Children.end() &&
"Not in immediate dominator children set!");
}
}
-DominatorTreeBase::Node *DominatorTree::getNodeForBlock(BasicBlock *BB) {
- Node *&BBNode = Nodes[BB];
- if (BBNode) return BBNode;
-
- // Haven't calculated this node yet? Get or calculate the node for the
- // immediate dominator.
- BasicBlock *IDom = getAnalysis<ImmediateDominators>()[BB];
- Node *IDomNode = getNodeForBlock(IDom);
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- return BBNode = IDomNode->addChild(new Node(BB, IDomNode));
-}
-
-void DominatorTree::calculate(const ImmediateDominators &ID) {
- assert(Roots.size() == 1 && "DominatorTree should have 1 root block!");
- BasicBlock *Root = Roots[0];
- Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the root...
-
- Function *F = Root->getParent();
- // Loop over all of the reachable blocks in the function...
- for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
- if (BasicBlock *ImmDom = ID.get(I)) { // Reachable block.
- Node *&BBNode = Nodes[I];
- if (!BBNode) { // Haven't calculated this node yet?
- // Get or calculate the node for the immediate dominator
- Node *IDomNode = getNodeForBlock(ImmDom);
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- BBNode = IDomNode->addChild(new Node(I, IDomNode));
- }
- }
-}
-
-static std::ostream &operator<<(std::ostream &o,
- const DominatorTreeBase::Node *Node) {
+static std::ostream &operator<<(std::ostream &o, const DomTreeNode *Node) {
if (Node->getBlock())
WriteAsOperand(o, Node->getBlock(), false);
else
o << " <<exit node>>";
+
+ o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
+
return o << "\n";
}
-static void PrintDomTree(const DominatorTreeBase::Node *N, std::ostream &o,
+static void PrintDomTree(const DomTreeNode *N, std::ostream &o,
unsigned Lev) {
o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N;
- for (DominatorTreeBase::Node::const_iterator I = N->begin(), E = N->end();
+ for (DomTreeNode::const_iterator I = N->begin(), E = N->end();
I != E; ++I)
PrintDomTree(*I, o, Lev+1);
}
+/// eraseNode - Removes a node from the domiantor tree. Block must not
+/// domiante any other blocks. Removes node from its immediate dominator's
+/// children list. Deletes dominator node associated with basic block BB.
+void DominatorTreeBase::eraseNode(BasicBlock *BB) {
+ DomTreeNode *Node = getNode(BB);
+ assert (Node && "Removing node that isn't in dominator tree.");
+ assert (Node->getChildren().empty() && "Node is not a leaf node.");
+
+ // Remove node from immediate dominator's children list.
+ DomTreeNode *IDom = Node->getIDom();
+ if (IDom) {
+ std::vector<DomTreeNode*>::iterator I =
+ std::find(IDom->Children.begin(), IDom->Children.end(), Node);
+ assert(I != IDom->Children.end() &&
+ "Not in immediate dominator children set!");
+ // I am no longer your child...
+ IDom->Children.erase(I);
+ }
+
+ DomTreeNodes.erase(BB);
+ delete Node;
+}
+
void DominatorTreeBase::print(std::ostream &o, const Module* ) const {
- o << "=============================--------------------------------\n"
- << "Inorder Dominator Tree:\n";
+ o << "=============================--------------------------------\n";
+ o << "Inorder Dominator Tree: ";
+ if (DFSInfoValid)
+ o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
+ o << "\n";
+
PrintDomTree(getRootNode(), o, 1);
}
+void DominatorTreeBase::dump() {
+ print(llvm::cerr);
+}
+
+bool DominatorTree::runOnFunction(Function &F) {
+ reset(); // Reset from the last time we were run...
+ Roots.push_back(&F.getEntryBlock());
+ DTcalculate(*this, F);
+ return false;
+}
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
//===----------------------------------------------------------------------===//
-static RegisterAnalysis<DominanceFrontier>
+char DominanceFrontier::ID = 0;
+static RegisterPass<DominanceFrontier>
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...
+// NewBB is split and now it has one successor. Update dominace frontier to
+// reflect this change.
+void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
+ assert(NewBB->getTerminator()->getNumSuccessors() == 1
+ && "NewBB should have a single successor!");
+ BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
+
+ std::vector<BasicBlock*> PredBlocks;
+ for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
+ PI != PE; ++PI)
+ PredBlocks.push_back(*PI);
+
+ if (PredBlocks.empty())
+ // If NewBB does not have any predecessors then it is a entry block.
+ // In this case, NewBB and its successor NewBBSucc dominates all
+ // other blocks.
+ return;
- 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);
+ // NewBBSucc inherits original NewBB frontier.
+ DominanceFrontier::iterator NewBBI = find(NewBB);
+ if (NewBBI != end()) {
+ DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
+ DominanceFrontier::DomSetType NewBBSuccSet;
+ NewBBSuccSet.insert(NewBBSet.begin(), NewBBSet.end());
+ addBasicBlock(NewBBSucc, NewBBSuccSet);
}
- // 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)
+ // If NewBB dominates NewBBSucc, then DF(NewBB) is now going to be the
+ // DF(PredBlocks[0]) without the stuff that the new block does not dominate
+ // a predecessor of.
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ if (DT.dominates(NewBB, NewBBSucc)) {
+ DominanceFrontier::iterator DFI = find(PredBlocks[0]);
+ if (DFI != end()) {
+ DominanceFrontier::DomSetType Set = DFI->second;
+ // Filter out stuff in Set that we do not dominate a predecessor of.
+ for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
+ E = Set.end(); SetI != E;) {
+ bool DominatesPred = false;
+ for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
+ PI != E; ++PI)
+ if (DT.dominates(NewBB, *PI))
+ DominatesPred = true;
+ if (!DominatesPred)
+ Set.erase(SetI++);
+ else
+ ++SetI;
+ }
+
+ if (NewBBI != end()) {
+ DominanceFrontier::DomSetType NewBBSet = NewBBI->second;
+ NewBBSet.insert(Set.begin(), Set.end());
+ } else
+ addBasicBlock(NewBB, Set);
+ }
+
+ } else {
+ // DF(NewBB) is {NewBBSucc} because NewBB does not strictly dominate
+ // NewBBSucc, but it does dominate itself (and there is an edge (NewBB ->
+ // NewBBSucc)). NewBBSucc is the single successor of NewBB.
+ DominanceFrontier::DomSetType NewDFSet;
+ NewDFSet.insert(NewBBSucc);
+ addBasicBlock(NewBB, NewDFSet);
+ }
+
+ // Now we must loop over all of the dominance frontiers in the function,
+ // replacing occurrences of NewBBSucc with NewBB in some cases. All
+ // blocks that dominate a block in PredBlocks and contained NewBBSucc in
+ // their dominance frontier must be updated to contain NewBB instead.
//
- for (DominatorTree::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);
+ for (Function::iterator FI = NewBB->getParent()->begin(),
+ FE = NewBB->getParent()->end(); FI != FE; ++FI) {
+ DominanceFrontier::iterator DFI = find(FI);
+ if (DFI == end()) continue; // unreachable block.
+
+ // Only consider nodes that have NewBBSucc in their dominator frontier.
+ if (!DFI->second.count(NewBBSucc)) continue;
+
+ // Verify whether this block dominates a block in predblocks. If not, do
+ // not update it.
+ bool BlockDominatesAny = false;
+ for (std::vector<BasicBlock*>::const_iterator BI = PredBlocks.begin(),
+ BE = PredBlocks.end(); BI != BE; ++BI) {
+ if (DT.dominates(FI, *BI)) {
+ BlockDominatesAny = true;
+ break;
+ }
+ }
+
+ if (!BlockDominatesAny)
+ continue;
+
+ // If NewBBSucc should not stay in our dominator frontier, remove it.
+ // We remove it unless there is a predecessor of NewBBSucc that we
+ // dominate, but we don't strictly dominate NewBBSucc.
+ bool ShouldRemove = true;
+ if ((BasicBlock*)FI == NewBBSucc || !DT.dominates(FI, NewBBSucc)) {
+ // Okay, we know that PredDom does not strictly dominate NewBBSucc.
+ // Check to see if it dominates any predecessors of NewBBSucc.
+ for (pred_iterator PI = pred_begin(NewBBSucc),
+ E = pred_end(NewBBSucc); PI != E; ++PI)
+ if (DT.dominates(FI, *PI)) {
+ ShouldRemove = false;
+ break;
+ }
}
+
+ if (ShouldRemove)
+ removeFromFrontier(DFI, NewBBSucc);
+ addToFrontier(DFI, NewBB);
}
+}
+
+namespace {
+ class DFCalculateWorkObject {
+ public:
+ DFCalculateWorkObject(BasicBlock *B, BasicBlock *P,
+ const DomTreeNode *N,
+ const DomTreeNode *PN)
+ : currentBB(B), parentBB(P), Node(N), parentNode(PN) {}
+ BasicBlock *currentBB;
+ BasicBlock *parentBB;
+ const DomTreeNode *Node;
+ const DomTreeNode *parentNode;
+ };
+}
+
+const DominanceFrontier::DomSetType &
+DominanceFrontier::calculate(const DominatorTree &DT,
+ const DomTreeNode *Node) {
+ BasicBlock *BB = Node->getBlock();
+ DomSetType *Result = NULL;
+
+ std::vector<DFCalculateWorkObject> workList;
+ SmallPtrSet<BasicBlock *, 32> visited;
+
+ workList.push_back(DFCalculateWorkObject(BB, NULL, Node, NULL));
+ do {
+ DFCalculateWorkObject *currentW = &workList.back();
+ assert (currentW && "Missing work object.");
+
+ BasicBlock *currentBB = currentW->currentBB;
+ BasicBlock *parentBB = currentW->parentBB;
+ const DomTreeNode *currentNode = currentW->Node;
+ const DomTreeNode *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);
+ }
+ }
+
+ // 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 (DomTreeNode::const_iterator NI = currentNode->begin(),
+ NE = currentNode->end(); NI != NE; ++NI) {
+ DomTreeNode *IDominee = *NI;
+ BasicBlock *childBB = IDominee->getBlock();
+ if (visited.count(childBB) == 0) {
+ workList.push_back(DFCalculateWorkObject(childBB, currentBB,
+ IDominee, currentNode));
+ 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;
+ }
- return S;
+ DomSetType::const_iterator CDFI = S.begin(), CDFE = S.end();
+ DomSetType &parentSet = Frontiers[parentBB];
+ for (; CDFI != CDFE; ++CDFI) {
+ if (!DT.properlyDominates(parentNode, DT[*CDFI]))
+ parentSet.insert(*CDFI);
+ }
+ workList.pop_back();
+ }
+
+ } while (!workList.empty());
+
+ return *Result;
}
void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {
}
}
+void DominanceFrontierBase::dump() {
+ print (llvm::cerr);
+}
projects / oota-llvm.git / blobdiff