//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Assembly/Writer.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/DominatorInternals.h"
#include "llvm/Instructions.h"
-#include "llvm/Support/Streams.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/CommandLine.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;
-}
-}
+// Always verify dominfo if expensive checking is enabled.
+#ifdef XDEBUG
+static bool VerifyDomInfo = true;
+#else
+static bool VerifyDomInfo = false;
+#endif
+static cl::opt<bool,true>
+VerifyDomInfoX("verify-dom-info", cl::location(VerifyDomInfo),
+ cl::desc("Verify dominator info (time consuming)"));
//===----------------------------------------------------------------------===//
// DominatorTree Implementation
//===----------------------------------------------------------------------===//
//
-// DominatorTree 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.
//
//===----------------------------------------------------------------------===//
-char DominatorTree::ID = 0;
-static RegisterPass<DominatorTree>
-E("domtree", "Dominator Tree Construction", true);
-
-// 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);
-
- std::vector<BasicBlock*> PredBlocks;
- for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
- PI != PE; ++PI)
- PredBlocks.push_back(*PI);
-
- assert(!PredBlocks.empty() && "No predblocks??");
-
- // 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];
- }
-
- for (; i != e; ++i)
- if (PredBlocks[i] != OnePred && isReachableFromEntry(OnePred)){
- NewBBDominatesNewBBSucc = false;
- break;
- }
-
- 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;
- }
- }
-
- // 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;
- }
- }
-
+TEMPLATE_INSTANTIATION(class llvm::DomTreeNodeBase<BasicBlock>);
+TEMPLATE_INSTANTIATION(class llvm::DominatorTreeBase<BasicBlock>);
- // 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]);
- }
- 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);
- }
-}
-
-unsigned DominatorTree::DFSPass(BasicBlock *V, InfoRec &VInfo,
- unsigned N) {
- // This is more understandable as a recursive algorithm, but we can't use the
- // recursive algorithm due to stack depth issues. Keep it here for
- // documentation purposes.
-#if 0
- VInfo.Semi = ++N;
- VInfo.Label = V;
-
- Vertex.push_back(V); // Vertex[n] = V;
- //Info[V].Ancestor = 0; // Ancestor[n] = 0
- //Info[V].Child = 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);
- }
- }
-#else
- std::vector<std::pair<BasicBlock*, unsigned> > Worklist;
- Worklist.push_back(std::make_pair(V, 0U));
- while (!Worklist.empty()) {
- BasicBlock *BB = Worklist.back().first;
- unsigned NextSucc = Worklist.back().second;
-
- // First time we visited this BB?
- if (NextSucc == 0) {
- InfoRec &BBInfo = Info[BB];
- BBInfo.Semi = ++N;
- BBInfo.Label = BB;
-
- Vertex.push_back(BB); // Vertex[n] = V;
- //BBInfo[V].Ancestor = 0; // Ancestor[n] = 0
- //BBInfo[V].Child = 0; // Child[v] = 0
- BBInfo.Size = 1; // Size[v] = 1
- }
-
- // If we are done with this block, remove it from the worklist.
- if (NextSucc == BB->getTerminator()->getNumSuccessors()) {
- Worklist.pop_back();
- continue;
- }
-
- // Otherwise, increment the successor number for the next time we get to it.
- ++Worklist.back().second;
-
- // Visit the successor next, if it isn't already visited.
- BasicBlock *Succ = BB->getTerminator()->getSuccessor(NextSucc);
-
- InfoRec &SuccVInfo = Info[Succ];
- if (SuccVInfo.Semi == 0) {
- SuccVInfo.Parent = BB;
- Worklist.push_back(std::make_pair(Succ, 0U));
- }
- }
-#endif
- return N;
-}
-
-void DominatorTree::Compress(BasicBlock *VIn) {
-
- std::vector<BasicBlock *> Work;
- std::set<BasicBlock *> Visited;
- InfoRec &VInInfo = Info[VIn];
- BasicBlock *VInAncestor = VInInfo.Ancestor;
- InfoRec &VInVAInfo = Info[VInAncestor];
-
- if (VInVAInfo.Ancestor != 0)
- Work.push_back(VIn);
-
- while (!Work.empty()) {
- BasicBlock *V = Work.back();
- InfoRec &VInfo = Info[V];
- BasicBlock *VAncestor = VInfo.Ancestor;
- InfoRec &VAInfo = Info[VAncestor];
-
- // Process Ancestor first
- if (Visited.count(VAncestor) == 0 && VAInfo.Ancestor != 0) {
- Work.push_back(VAncestor);
- Visited.insert(VAncestor);
- continue;
- }
- Work.pop_back();
-
- // Update VINfo based on Ancestor info
- if (VAInfo.Ancestor == 0)
- continue;
- BasicBlock *VAncestorLabel = VAInfo.Label;
- BasicBlock *VLabel = VInfo.Label;
- if (Info[VAncestorLabel].Semi < Info[VLabel].Semi)
- VInfo.Label = VAncestorLabel;
- VInfo.Ancestor = VAInfo.Ancestor;
- }
-}
-
-BasicBlock *DominatorTree::Eval(BasicBlock *V) {
- InfoRec &VInfo = Info[V];
-#if !BALANCE_IDOM_TREE
- // Higher-complexity but faster implementation
- if (VInfo.Ancestor == 0)
- return V;
- Compress(V);
- return VInfo.Label;
-#else
- // Lower-complexity but slower implementation
- if (VInfo.Ancestor == 0)
- return VInfo.Label;
- Compress(V);
- BasicBlock *VLabel = VInfo.Label;
-
- BasicBlock *VAncestorLabel = Info[VInfo.Ancestor].Label;
- if (Info[VAncestorLabel].Semi >= Info[VLabel].Semi)
- return VLabel;
- else
- return VAncestorLabel;
-#endif
-}
-
-void DominatorTree::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];
- }
- }
-
- 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);
+char DominatorTree::ID = 0;
+INITIALIZE_PASS(DominatorTree, "domtree",
+ "Dominator Tree Construction", true, true);
- while (S) {
- SInfo = &Info[S];
- SInfo->Ancestor = V;
- S = SInfo->Child;
- }
-#endif
+bool DominatorTree::runOnFunction(Function &F) {
+ DT->recalculate(F);
+ return false;
}
-void DominatorTree::calculate(Function& F) {
- BasicBlock* Root = Roots[0];
-
- // Add a node for the root...
- DomTreeNodes[Root] = RootNode = new DomTreeNode(Root, 0);
-
- 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;
- }
-
- 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;
- }
- }
-
- // 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];
- }
-
- // 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 = getIDom(I)) { // Reachable block.
- DomTreeNode *&BBNode = DomTreeNodes[I];
- if (!BBNode) { // Haven't calculated this node yet?
- // Get or calculate the node for the immediate dominator
- DomTreeNode *IDomNode = getNodeForBlock(ImmDom);
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- DomTreeNode *C = new DomTreeNode(I, IDomNode);
- DomTreeNodes[I] = C;
- BBNode = IDomNode->addChild(C);
- }
- }
-
- // Free temporary memory used to construct idom's
- Info.clear();
- IDoms.clear();
- std::vector<BasicBlock*>().swap(Vertex);
+void DominatorTree::verifyAnalysis() const {
+ if (!VerifyDomInfo) return;
- updateDFSNumbers();
-}
+ Function &F = *getRoot()->getParent();
-void DominatorTreeBase::updateDFSNumbers()
-{
- int dfsnum = 0;
- // Iterate over all nodes in depth first order.
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- for (df_iterator<BasicBlock*> I = df_begin(Roots[i]),
- E = df_end(Roots[i]); I != E; ++I) {
- BasicBlock *BB = *I;
- DomTreeNode *BBNode = getNode(BB);
- if (BBNode) {
- if (!BBNode->getIDom())
- BBNode->assignDFSNumber(dfsnum);
- }
- }
- SlowQueries = 0;
- DFSInfoValid = true;
+ DominatorTree OtherDT;
+ OtherDT.getBase().recalculate(F);
+ assert(!compare(OtherDT) && "Invalid DominatorTree info!");
}
-/// 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);
+void DominatorTree::print(raw_ostream &OS, const Module *) const {
+ DT->print(OS);
}
-// dominates - Return true if A dominates B. THis performs the
+// dominates - Return true if A dominates a use in 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();
+bool DominatorTree::dominates(const Instruction *A, const Instruction *B) const{
+ const BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
+
+ // If A is an invoke instruction, its value is only available in this normal
+ // successor block.
+ if (const InvokeInst *II = dyn_cast<InvokeInst>(A))
+ BBA = II->getNormalDest();
+
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*/;
-
- 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;
- }
-}
-
-// DominatorTreeBase::reset - Free all of the tree node memory.
-//
-void DominatorTreeBase::reset() {
- for (DomTreeNodeMapType::iterator I = DomTreeNodes.begin(),
- E = DomTreeNodes.end(); I != E; ++I)
- delete I->second;
- DomTreeNodes.clear();
- IDoms.clear();
- Roots.clear();
- Vertex.clear();
- RootNode = 0;
-}
-
-/// 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();
- }
-
- // Walk NodeB immediate dominators chain and find common dominator node.
- DomTreeNode *IDomB = NodeB->getIDom();
- while(IDomB) {
- if (NodeADoms.count(IDomB) != 0)
- return IDomB->getBlock();
-
- IDomB = IDomB->getIDom();
- }
-
- return NULL;
-}
-
-/// assignDFSNumber - Assign In and Out numbers while walking dominator tree
-/// in dfs order.
-void DomTreeNode::assignDFSNumber(int num) {
- std::vector<DomTreeNode *> workStack;
- std::set<DomTreeNode *> visitedNodes;
- workStack.push_back(this);
- visitedNodes.insert(this);
- this->DFSNumIn = num++;
+ // Loop through the basic block until we find A or B.
+ BasicBlock::const_iterator I = BBA->begin();
+ for (; &*I != A && &*I != B; ++I)
+ /*empty*/;
- while (!workStack.empty()) {
- DomTreeNode *Node = workStack.back();
-
- bool visitChild = false;
- for (std::vector<DomTreeNode*>::iterator DI = Node->begin(),
- E = Node->end(); DI != E && !visitChild; ++DI) {
- DomTreeNode *Child = *DI;
- if (visitedNodes.count(Child) == 0) {
- visitChild = true;
- Child->DFSNumIn = num++;
- workStack.push_back(Child);
- visitedNodes.insert(Child);
- }
- }
- if (!visitChild) {
- // If we reach here means all children are visited
- Node->DFSNumOut = num++;
- workStack.pop_back();
- }
- }
-}
-
-void DomTreeNode::setIDom(DomTreeNode *NewIDom) {
- assert(IDom && "No immediate dominator?");
- if (IDom != NewIDom) {
- 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!");
- // I am no longer your child...
- IDom->Children.erase(I);
-
- // Switch to new dominator
- IDom = NewIDom;
- IDom->Children.push_back(this);
- }
+ return &*I == A;
}
-DomTreeNode *DominatorTree::getNodeForBlock(BasicBlock *BB) {
- DomTreeNode *&BBNode = DomTreeNodes[BB];
- if (BBNode) return BBNode;
- // 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);
- DomTreeNodes[BB] = C;
- return BBNode = IDomNode->addChild(C);
-}
-
-static std::ostream &operator<<(std::ostream &o,
- const DomTreeNode *Node) {
- if (Node->getBlock())
- WriteAsOperand(o, Node->getBlock(), false);
- else
- o << " <<exit node>>";
- return o << "\n";
-}
-
-static void PrintDomTree(const DomTreeNode *N, std::ostream &o,
- unsigned Lev) {
- o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N;
- for (DomTreeNode::const_iterator I = N->begin(), E = N->end();
- I != E; ++I)
- PrintDomTree(*I, o, Lev+1);
-}
-
-void DominatorTreeBase::print(std::ostream &o, const Module* ) const {
- o << "=============================--------------------------------\n"
- << "Inorder Dominator Tree:\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());
- calculate(F);
- return false;
-}
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
//===----------------------------------------------------------------------===//
char DominanceFrontier::ID = 0;
-static RegisterPass<DominanceFrontier>
-G("domfrontier", "Dominance Frontier Construction", true);
+INITIALIZE_PASS(DominanceFrontier, "domfrontier",
+ "Dominance Frontier Construction", true, true);
-// NewBB is split and now it has one successor. Update dominace frontier to
-// reflect this change.
-void DominanceFrontier::splitBlock(BasicBlock *NewBB) {
+void DominanceFrontier::verifyAnalysis() const {
+ if (!VerifyDomInfo) return;
- assert(NewBB->getTerminator()->getNumSuccessors() == 1
- && "NewBB should have a single successor!");
- BasicBlock *NewBBSucc = NewBB->getTerminator()->getSuccessor(0);
+ DominatorTree &DT = getAnalysis<DominatorTree>();
- std::vector<BasicBlock*> PredBlocks;
- for (pred_iterator PI = pred_begin(NewBB), PE = pred_end(NewBB);
- PI != PE; ++PI)
- PredBlocks.push_back(*PI);
+ DominanceFrontier OtherDF;
+ const std::vector<BasicBlock*> &DTRoots = DT.getRoots();
+ OtherDF.calculate(DT, DT.getNode(DTRoots[0]));
+ assert(!compare(OtherDF) && "Invalid DominanceFrontier info!");
+}
- assert(!PredBlocks.empty() && "No predblocks??");
+// NewBB is split and now it has one successor. Update dominance 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);
- DominatorTree &DT = getAnalysis<DominatorTree>();
- bool NewBBDominatesNewBBSucc = true;
- if (!DT.dominates(NewBB, NewBBSucc))
- NewBBDominatesNewBBSucc = false;
+ // NewBBSucc inherits original NewBB frontier.
+ DominanceFrontier::iterator NewBBI = find(NewBB);
+ if (NewBBI != end())
+ addBasicBlock(NewBBSucc, NewBBI->second);
// 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
+ // DF(NewBBSucc) without the stuff that the new block does not dominate
// a predecessor of.
- if (NewBBDominatesNewBBSucc) {
- DominanceFrontier::iterator DFI = find(PredBlocks[0]);
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ DomTreeNode *NewBBNode = DT.getNode(NewBB);
+ DomTreeNode *NewBBSuccNode = DT.getNode(NewBBSucc);
+ if (DT.dominates(NewBBNode, NewBBSuccNode)) {
+ DominanceFrontier::iterator DFI = find(NewBBSucc);
if (DFI != end()) {
DominanceFrontier::DomSetType Set = DFI->second;
// Filter out stuff in Set that we do not dominate a predecessor of.
bool DominatesPred = false;
for (pred_iterator PI = pred_begin(*SetI), E = pred_end(*SetI);
PI != E; ++PI)
- if (DT.dominates(NewBB, *PI))
+ if (DT.dominates(NewBBNode, DT.getNode(*PI))) {
DominatesPred = true;
+ break;
+ }
if (!DominatesPred)
Set.erase(SetI++);
else
++SetI;
}
-
- addBasicBlock(NewBB, Set);
+
+ if (NewBBI != end()) {
+ for (DominanceFrontier::DomSetType::iterator SetI = Set.begin(),
+ E = Set.end(); SetI != E; ++SetI) {
+ BasicBlock *SB = *SetI;
+ addToFrontier(NewBBI, SB);
+ }
+ } else
+ addBasicBlock(NewBB, Set);
}
} else {
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 (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 dominators of NewBBSucc
- if (!DFI->second.count(NewBBSucc)) continue;
-
- 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;
+
+ // Now update dominance frontiers which either used to contain NewBBSucc
+ // or which now need to include NewBB.
+
+ // Collect the set of blocks which dominate a predecessor of NewBB or
+ // NewSuccBB and which don't dominate both. This is an initial
+ // approximation of the blocks whose dominance frontiers will need updates.
+ SmallVector<DomTreeNode *, 16> AllPredDoms;
+
+ // Compute the block which dominates both NewBBSucc and NewBB. This is
+ // the immediate dominator of NewBBSucc unless NewBB dominates NewBBSucc.
+ // The code below which climbs dominator trees will stop at this point,
+ // because from this point up, dominance frontiers are unaffected.
+ DomTreeNode *DominatesBoth = 0;
+ if (NewBBSuccNode) {
+ DominatesBoth = NewBBSuccNode->getIDom();
+ if (DominatesBoth == NewBBNode)
+ DominatesBoth = NewBBNode->getIDom();
+ }
+
+ // Collect the set of all blocks which dominate a predecessor of NewBB.
+ SmallPtrSet<DomTreeNode *, 8> NewBBPredDoms;
+ for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB); PI != E; ++PI)
+ for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
+ if (DTN == DominatesBoth)
break;
- }
+ if (!NewBBPredDoms.insert(DTN))
+ break;
+ AllPredDoms.push_back(DTN);
}
-
- if (BlockDominatesAny) {
- // 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);
-
+
+ // Collect the set of all blocks which dominate a predecessor of NewSuccBB.
+ SmallPtrSet<DomTreeNode *, 8> NewBBSuccPredDoms;
+ for (pred_iterator PI = pred_begin(NewBBSucc),
+ E = pred_end(NewBBSucc); PI != E; ++PI)
+ for (DomTreeNode *DTN = DT.getNode(*PI); DTN; DTN = DTN->getIDom()) {
+ if (DTN == DominatesBoth)
break;
- }
+ if (!NewBBSuccPredDoms.insert(DTN))
+ break;
+ if (!NewBBPredDoms.count(DTN))
+ AllPredDoms.push_back(DTN);
}
+
+ // Visit all relevant dominance frontiers and make any needed updates.
+ for (SmallVectorImpl<DomTreeNode *>::const_iterator I = AllPredDoms.begin(),
+ E = AllPredDoms.end(); I != E; ++I) {
+ DomTreeNode *DTN = *I;
+ iterator DFI = find((*I)->getBlock());
+
+ // Only consider nodes that have NewBBSucc in their dominator frontier.
+ if (DFI == end() || !DFI->second.count(NewBBSucc)) continue;
+
+ // If the block dominates a predecessor of NewBB but does not properly
+ // dominate NewBB itself, add NewBB to its dominance frontier.
+ if (NewBBPredDoms.count(DTN) &&
+ !DT.properlyDominates(DTN, NewBBNode))
+ addToFrontier(DFI, NewBB);
+
+ // If the block does not dominate a predecessor of NewBBSucc or
+ // properly dominates NewBBSucc itself, remove NewBBSucc from its
+ // dominance frontier.
+ if (!NewBBSuccPredDoms.count(DTN) ||
+ DT.properlyDominates(DTN, NewBBSuccNode))
+ removeFromFrontier(DFI, NewBBSucc);
}
}
return *Result;
}
-void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {
+void DominanceFrontierBase::print(raw_ostream &OS, const Module* ) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
- o << " DomFrontier for BB";
+ OS << " DomFrontier for BB ";
if (I->first)
- WriteAsOperand(o, I->first, false);
+ WriteAsOperand(OS, I->first, false);
else
- o << " <<exit node>>";
- o << " is:\t" << I->second << "\n";
+ OS << " <<exit node>>";
+ OS << " is:\t";
+
+ const std::set<BasicBlock*> &BBs = I->second;
+
+ for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
+ I != E; ++I) {
+ OS << ' ';
+ if (*I)
+ WriteAsOperand(OS, *I, false);
+ else
+ OS << "<<exit node>>";
+ }
+ OS << "\n";
}
}
-void DominanceFrontierBase::dump() {
- print (llvm::cerr);
+void DominanceFrontierBase::dump() const {
+ print(dbgs());
}
+
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