X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FDominators.cpp;h=219e6315cf4e4adccd536afb75477c9b87082f2a;hb=9777f61bfe36a53757977cd777f2b4e73fc3e8a3;hp=9bfbbec9b9b22a40d56e7a87784c2451cb1ea608;hpb=9a51157db555395f7a6ad89faec40b3afa121091;p=oota-llvm.git diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp index 9bfbbec9b9b..219e6315cf4 100644 --- a/lib/VMCore/Dominators.cpp +++ b/lib/VMCore/Dominators.cpp @@ -2,8 +2,8 @@ // // 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. // //===----------------------------------------------------------------------===// // @@ -16,1059 +16,251 @@ #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/Assembly/Writer.h" #include "llvm/Instructions.h" -#include "llvm/Support/Streams.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Support/CommandLine.h" #include using namespace llvm; -namespace llvm { -static std::ostream &operator<<(std::ostream &o, - const std::set &BBs) { - for (std::set::const_iterator I = BBs.begin(), E = BBs.end(); - I != E; ++I) - if (*I) - WriteAsOperand(o, *I, false); - else - o << " <>"; - 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 +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 DominatorInternals.h. // //===----------------------------------------------------------------------===// -char DominatorTree::ID = 0; -static RegisterPass -E("domtree", "Dominator Tree Construction", true); - -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 > 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 Work; - std::set 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); - - while (S) { - SInfo = &Info[S]; - SInfo->Ancestor = V; - S = SInfo->Child; - } -#endif -} - -void DominatorTree::calculate(Function& F) { - BasicBlock* Root = Roots[0]; - - // Add a node for the root... - ETNode *ERoot = new ETNode(Root); - ETNodes[Root] = ERoot; - DomTreeNodes[Root] = RootNode = new DomTreeNode(Root, 0, ERoot); +TEMPLATE_INSTANTIATION(class llvm::DomTreeNodeBase); +TEMPLATE_INSTANTIATION(class llvm::DominatorTreeBase); - 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 &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 - ETNode *ET = new ETNode(I); - ETNodes[I] = ET; - DomTreeNode *C = new DomTreeNode(I, IDomNode, ET); - DomTreeNodes[I] = C; - BBNode = IDomNode->addChild(C); - } - } - - // Free temporary memory used to construct idom's - Info.clear(); - IDoms.clear(); - std::vector().swap(Vertex); - - updateDFSNumbers(); -} - -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 I = df_begin(Roots[i]), - E = df_end(Roots[i]); I != E; ++I) { - BasicBlock *BB = *I; - ETNode *ETN = getNode(BB)->getETNode(); - if (ETN && !ETN->hasFather()) - ETN->assignDFSNumber(dfsnum); - } - SlowQueries = 0; - DFSInfoValid = true; -} - - -// 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; -} - -void DomTreeNode::setIDom(DomTreeNode *NewIDom) { - assert(IDom && "No immediate dominator?"); - if (IDom != NewIDom) { - std::vector::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); - - if (!ETN->hasFather()) - ETN->setFather(IDom->getETNode()); - else if (ETN->getFather()->getData() != IDom->getBlock()) { - ETN->Split(); - ETN->setFather(IDom->getETNode()); - } - } -} - -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 - ETNode *ET = new ETNode(BB); - ETNodes[BB] = ET; - DomTreeNode *C = new DomTreeNode(BB, IDomNode, ET); - 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 << " <>"; - 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); -} +char DominatorTree::ID = 0; +INITIALIZE_PASS(DominatorTree, "domtree", + "Dominator Tree Construction", true, true) bool DominatorTree::runOnFunction(Function &F) { - reset(); // Reset from the last time we were run... - Roots.push_back(&F.getEntryBlock()); - calculate(F); + DT->recalculate(F); return false; } -//===----------------------------------------------------------------------===// -// DominanceFrontier Implementation -//===----------------------------------------------------------------------===// - -char DominanceFrontier::ID = 0; -static RegisterPass -G("domfrontier", "Dominance Frontier Construction", true); - -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 workList; - SmallPtrSet 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; - } - - 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 { - for (const_iterator I = begin(), E = end(); I != E; ++I) { - o << " DomFrontier for BB"; - if (I->first) - WriteAsOperand(o, I->first, false); - else - o << " <>"; - o << " is:\t" << I->second << "\n"; - } -} - -void DominanceFrontierBase::dump() { - print (llvm::cerr); -} - +void DominatorTree::verifyAnalysis() const { + if (!VerifyDomInfo) return; -//===----------------------------------------------------------------------===// -// ETOccurrence Implementation -//===----------------------------------------------------------------------===// + Function &F = *getRoot()->getParent(); -void ETOccurrence::Splay() { - ETOccurrence *father; - ETOccurrence *grandfather; - int occdepth; - int fatherdepth; - - while (Parent) { - occdepth = Depth; - - father = Parent; - fatherdepth = Parent->Depth; - grandfather = father->Parent; - - // If we have no grandparent, a single zig or zag will do. - if (!grandfather) { - setDepthAdd(fatherdepth); - MinOccurrence = father->MinOccurrence; - Min = father->Min; - - // See what we have to rotate - if (father->Left == this) { - // Zig - father->setLeft(Right); - setRight(father); - if (father->Left) - father->Left->setDepthAdd(occdepth); - } else { - // Zag - father->setRight(Left); - setLeft(father); - if (father->Right) - father->Right->setDepthAdd(occdepth); - } - father->setDepth(-occdepth); - Parent = NULL; - - father->recomputeMin(); - return; - } - - // If we have a grandfather, we need to do some - // combination of zig and zag. - int grandfatherdepth = grandfather->Depth; - - setDepthAdd(fatherdepth + grandfatherdepth); - MinOccurrence = grandfather->MinOccurrence; - Min = grandfather->Min; - - ETOccurrence *greatgrandfather = grandfather->Parent; - - if (grandfather->Left == father) { - if (father->Left == this) { - // Zig zig - grandfather->setLeft(father->Right); - father->setLeft(Right); - setRight(father); - father->setRight(grandfather); - - father->setDepth(-occdepth); - - if (father->Left) - father->Left->setDepthAdd(occdepth); - - grandfather->setDepth(-fatherdepth); - if (grandfather->Left) - grandfather->Left->setDepthAdd(fatherdepth); - } else { - // Zag zig - grandfather->setLeft(Right); - father->setRight(Left); - setLeft(father); - setRight(grandfather); - - father->setDepth(-occdepth); - if (father->Right) - father->Right->setDepthAdd(occdepth); - grandfather->setDepth(-occdepth - fatherdepth); - if (grandfather->Left) - grandfather->Left->setDepthAdd(occdepth + fatherdepth); - } - } else { - if (father->Left == this) { - // Zig zag - grandfather->setRight(Left); - father->setLeft(Right); - setLeft(grandfather); - setRight(father); - - father->setDepth(-occdepth); - if (father->Left) - father->Left->setDepthAdd(occdepth); - grandfather->setDepth(-occdepth - fatherdepth); - if (grandfather->Right) - grandfather->Right->setDepthAdd(occdepth + fatherdepth); - } else { // Zag Zag - grandfather->setRight(father->Left); - father->setRight(Left); - setLeft(father); - father->setLeft(grandfather); - - father->setDepth(-occdepth); - if (father->Right) - father->Right->setDepthAdd(occdepth); - grandfather->setDepth(-fatherdepth); - if (grandfather->Right) - grandfather->Right->setDepthAdd(fatherdepth); - } - } - - // Might need one more rotate depending on greatgrandfather. - setParent(greatgrandfather); - if (greatgrandfather) { - if (greatgrandfather->Left == grandfather) - greatgrandfather->Left = this; - else - greatgrandfather->Right = this; - - } - grandfather->recomputeMin(); - father->recomputeMin(); + DominatorTree OtherDT; + OtherDT.getBase().recalculate(F); + if (compare(OtherDT)) { + errs() << "DominatorTree is not up to date!\nComputed:\n"; + print(errs()); + errs() << "\nActual:\n"; + OtherDT.print(errs()); + abort(); } } -//===----------------------------------------------------------------------===// -// ETNode implementation -//===----------------------------------------------------------------------===// - -void ETNode::Split() { - ETOccurrence *right, *left; - ETOccurrence *rightmost = RightmostOcc; - ETOccurrence *parent; - - // Update the occurrence tree first. - RightmostOcc->Splay(); - - // Find the leftmost occurrence in the rightmost subtree, then splay - // around it. - for (right = rightmost->Right; right->Left; right = right->Left); - - right->Splay(); - - // Start splitting - right->Left->Parent = NULL; - parent = ParentOcc; - parent->Splay(); - ParentOcc = NULL; - - left = parent->Left; - parent->Right->Parent = NULL; - - right->setLeft(left); - - right->recomputeMin(); - - rightmost->Splay(); - rightmost->Depth = 0; - rightmost->Min = 0; - - delete parent; - - // Now update *our* tree - - if (Father->Son == this) - Father->Son = Right; - - if (Father->Son == this) - Father->Son = NULL; - else { - Left->Right = Right; - Right->Left = Left; - } - Left = Right = NULL; - Father = NULL; +void DominatorTree::print(raw_ostream &OS, const Module *) const { + DT->print(OS); } -void ETNode::setFather(ETNode *NewFather) { - ETOccurrence *rightmost; - ETOccurrence *leftpart; - ETOccurrence *NewFatherOcc; - ETOccurrence *temp; - - // First update the path in the splay tree - NewFatherOcc = new ETOccurrence(NewFather); - - rightmost = NewFather->RightmostOcc; - rightmost->Splay(); +// dominates - Return true if Def dominates a use in User. This performs +// the special checks necessary if Def and User are in the same basic block. +// Note that Def doesn't dominate a use in Def itself! +bool DominatorTree::dominates(const Instruction *Def, + const Instruction *User) const { + const BasicBlock *UseBB = User->getParent(); + const BasicBlock *DefBB = Def->getParent(); - leftpart = rightmost->Left; - - temp = RightmostOcc; - temp->Splay(); - - NewFatherOcc->setLeft(leftpart); - NewFatherOcc->setRight(temp); - - temp->Depth++; - temp->Min++; - NewFatherOcc->recomputeMin(); - - rightmost->setLeft(NewFatherOcc); - - if (NewFatherOcc->Min + rightmost->Depth < rightmost->Min) { - rightmost->Min = NewFatherOcc->Min + rightmost->Depth; - rightmost->MinOccurrence = NewFatherOcc->MinOccurrence; - } + // Any unreachable use is dominated, even if Def == User. + if (!isReachableFromEntry(UseBB)) + return true; - delete ParentOcc; - ParentOcc = NewFatherOcc; + // Unreachable definitions don't dominate anything. + if (!isReachableFromEntry(DefBB)) + return false; - // Update *our* tree - ETNode *left; - ETNode *right; + // An instruction doesn't dominate a use in itself. + if (Def == User) + return false; - Father = NewFather; - right = Father->Son; + // The value defined by an invoke dominates an instruction only if + // it dominates every instruction in UseBB. + // A PHI is dominated only if the instruction dominates every possible use + // in the UseBB. + if (isa(Def) || isa(User)) + return dominates(Def, UseBB); - if (right) - left = right->Left; - else - left = right = this; + if (DefBB != UseBB) + return dominates(DefBB, UseBB); - left->Right = this; - right->Left = this; - Left = left; - Right = right; + // Loop through the basic block until we find Def or User. + BasicBlock::const_iterator I = DefBB->begin(); + for (; &*I != Def && &*I != User; ++I) + /*empty*/; - Father->Son = this; + return &*I == Def; } -bool ETNode::Below(ETNode *other) { - ETOccurrence *up = other->RightmostOcc; - ETOccurrence *down = RightmostOcc; +// true if Def would dominate a use in any instruction in UseBB. +// note that dominates(Def, Def->getParent()) is false. +bool DominatorTree::dominates(const Instruction *Def, + const BasicBlock *UseBB) const { + const BasicBlock *DefBB = Def->getParent(); - if (this == other) + // Any unreachable use is dominated, even if DefBB == UseBB. + if (!isReachableFromEntry(UseBB)) return true; - up->Splay(); - - ETOccurrence *left, *right; - left = up->Left; - right = up->Right; - - if (!left) + // Unreachable definitions don't dominate anything. + if (!isReachableFromEntry(DefBB)) return false; - left->Parent = NULL; - - if (right) - right->Parent = NULL; - - down->Splay(); - - if (left == down || left->Parent != NULL) { - if (right) - right->Parent = up; - up->setLeft(down); - } else { - left->Parent = up; - - // If the two occurrences are in different trees, put things - // back the way they were. - if (right && right->Parent != NULL) - up->setRight(down); - else - up->setRight(right); - return false; - } - - if (down->Depth <= 0) + if (DefBB == UseBB) return false; - return !down->Right || down->Right->Min + down->Depth >= 0; -} - -ETNode *ETNode::NCA(ETNode *other) { - ETOccurrence *occ1 = RightmostOcc; - ETOccurrence *occ2 = other->RightmostOcc; - - ETOccurrence *left, *right, *ret; - ETOccurrence *occmin; - int mindepth; - - if (this == other) - return this; - - occ1->Splay(); - left = occ1->Left; - right = occ1->Right; - - if (left) - left->Parent = NULL; - - if (right) - right->Parent = NULL; - occ2->Splay(); + const InvokeInst *II = dyn_cast(Def); + if (!II) + return dominates(DefBB, UseBB); - if (left == occ2 || (left && left->Parent != NULL)) { - ret = occ2->Right; - - occ1->setLeft(occ2); - if (right) - right->Parent = occ1; - } else { - ret = occ2->Left; - - occ1->setRight(occ2); - if (left) - left->Parent = occ1; - } - - if (occ2->Depth > 0) { - occmin = occ1; - mindepth = occ1->Depth; - } else { - occmin = occ2; - mindepth = occ2->Depth + occ1->Depth; - } - - if (ret && ret->Min + occ1->Depth + occ2->Depth < mindepth) - return ret->MinOccurrence->OccFor; - else - return occmin->OccFor; -} + // Invoke results are only usable in the normal destination, not in the + // exceptional destination. + BasicBlock *NormalDest = II->getNormalDest(); + if (!dominates(NormalDest, UseBB)) + return false; -void ETNode::assignDFSNumber(int num) { - std::vector workStack; - std::set visitedNodes; - - workStack.push_back(this); - visitedNodes.insert(this); - this->DFSNumIn = num++; + // Simple case: if the normal destination has a single predecessor, the + // fact that it dominates the use block implies that we also do. + if (NormalDest->getSinglePredecessor()) + return true; - while (!workStack.empty()) { - ETNode *Node = workStack.back(); - - // If this is leaf node then set DFSNumOut and pop the stack - if (!Node->Son) { - Node->DFSNumOut = num++; - workStack.pop_back(); - continue; - } - - ETNode *son = Node->Son; - - // Visit Node->Son first - if (visitedNodes.count(son) == 0) { - son->DFSNumIn = num++; - workStack.push_back(son); - visitedNodes.insert(son); + // The normal edge from the invoke is critical. Conceptually, what we would + // like to do is split it and check if the new block dominates the use. + // With X being the new block, the graph would look like: + // + // DefBB + // /\ . . + // / \ . . + // / \ . . + // / \ | | + // A X B C + // | \ | / + // . \|/ + // . NormalDest + // . + // + // Given the definition of dominance, NormalDest is dominated by X iff X + // dominates all of NormalDest's predecessors (X, B, C in the example). X + // trivially dominates itself, so we only have to find if it dominates the + // other predecessors. Since the only way out of X is via NormalDest, X can + // only properly dominate a node if NormalDest dominates that node too. + for (pred_iterator PI = pred_begin(NormalDest), + E = pred_end(NormalDest); PI != E; ++PI) { + const BasicBlock *BB = *PI; + if (BB == DefBB) continue; - } - - bool visitChild = false; - // Visit remaining children - for (ETNode *s = son->Right; s != son && !visitChild; s = s->Right) { - if (visitedNodes.count(s) == 0) { - visitChild = true; - s->DFSNumIn = num++; - workStack.push_back(s); - visitedNodes.insert(s); - } - } - - if (!visitChild) { - // If we reach here means all children are visited - Node->DFSNumOut = num++; - workStack.pop_back(); - } - } -} - -//===----------------------------------------------------------------------===// -// ETForest implementation -//===----------------------------------------------------------------------===// - -char ETForest::ID = 0; -static RegisterPass -D("etforest", "ET Forest Construction", true); - -void ETForestBase::reset() { - for (ETMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) - delete I->second; - Nodes.clear(); -} - -void ETForestBase::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 I = df_begin(Roots[i]), - E = df_end(Roots[i]); I != E; ++I) { - BasicBlock *BB = *I; - ETNode *ETN = getNode(BB); - if (ETN && !ETN->hasFather()) - ETN->assignDFSNumber(dfsnum); - } - SlowQueries = 0; - DFSInfoValid = 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 ETForestBase::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(A) && isa(B)) - return false; + if (!DT->isReachableFromEntry(BB)) + continue; - // 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; + if (!dominates(NormalDest, BB)) + return false; } + return true; } -/// isReachableFromEntry - Return true if A is dominated by the entry -/// block of the function containing it. -const bool ETForestBase::isReachableFromEntry(BasicBlock* A) { - return dominates(&A->getParent()->getEntryBlock(), A); -} - -// FIXME : There is no need to make getNodeForBlock public. Fix -// predicate simplifier. -ETNode *ETForest::getNodeForBlock(BasicBlock *BB) { - ETNode *&BBNode = Nodes[BB]; - if (BBNode) return BBNode; +bool DominatorTree::dominates(const Instruction *Def, + const Use &U) const { + Instruction *UserInst = dyn_cast(U.getUser()); - // Haven't calculated this node yet? Get or calculate the node for the - // immediate dominator. - DomTreeNode *node= getAnalysis().getNode(BB); + // Instructions do not dominate non-instructions. + if (!UserInst) + return false; - // If we are unreachable, we may not have an immediate dominator. - if (!node || !node->getIDom()) - return BBNode = new ETNode(BB); - else { - ETNode *IDomNode = getNodeForBlock(node->getIDom()->getBlock()); - - // Add a new tree node for this BasicBlock, and link it as a child of - // IDomNode - BBNode = new ETNode(BB); - BBNode->setFather(IDomNode); - return BBNode; - } -} + const BasicBlock *DefBB = Def->getParent(); -void ETForest::calculate(const DominatorTree &DT) { - assert(Roots.size() == 1 && "ETForest should have 1 root block!"); - BasicBlock *Root = Roots[0]; - Nodes[Root] = new ETNode(Root); // Add a node for the root + // Determine the block in which the use happens. PHI nodes use + // their operands on edges; simulate this by thinking of the use + // happening at the end of the predecessor block. + const BasicBlock *UseBB; + if (PHINode *PN = dyn_cast(UserInst)) + UseBB = PN->getIncomingBlock(U); + else + UseBB = UserInst->getParent(); - 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) { - DomTreeNode* node = DT.getNode(I); - if (node && node->getIDom()) { // Reachable block. - BasicBlock* ImmDom = node->getIDom()->getBlock(); - ETNode *&BBNode = Nodes[I]; - if (!BBNode) { // Haven't calculated this node yet? - // Get or calculate the node for the immediate dominator - ETNode *IDomNode = getNodeForBlock(ImmDom); + // Any unreachable use is dominated, even if Def == User. + if (!isReachableFromEntry(UseBB)) + return true; - // Add a new ETNode for this BasicBlock, and set it's parent - // to it's immediate dominator. - BBNode = new ETNode(I); - BBNode->setFather(IDomNode); - } - } - } + // Unreachable definitions don't dominate anything. + if (!isReachableFromEntry(DefBB)) + return false; - // Make sure we've got nodes around for every block - for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) { - ETNode *&BBNode = Nodes[I]; - if (!BBNode) - BBNode = new ETNode(I); + // Invoke instructions define their return values on the edges + // to their normal successors, so we have to handle them specially. + // Among other things, this means they don't dominate anything in + // their own block, except possibly a phi, so we don't need to + // walk the block in any case. + if (const InvokeInst *II = dyn_cast(Def)) { + // A PHI in the normal successor using the invoke's return value is + // dominated by the invoke's return value. + if (isa(UserInst) && + UserInst->getParent() == II->getNormalDest() && + cast(UserInst)->getIncomingBlock(U) == DefBB) + return true; + + // Otherwise use the instruction-dominates-block query, which + // handles the crazy case of an invoke with a critical edge + // properly. + return dominates(Def, UseBB); } - updateDFSNumbers (); -} + // If the def and use are in different blocks, do a simple CFG dominator + // tree query. + if (DefBB != UseBB) + return dominates(DefBB, UseBB); -//===----------------------------------------------------------------------===// -// ETForestBase Implementation -//===----------------------------------------------------------------------===// + // Ok, def and use are in the same block. If the def is an invoke, it + // doesn't dominate anything in the block. If it's a PHI, it dominates + // everything in the block. + if (isa(UserInst)) + return true; -void ETForestBase::addNewBlock(BasicBlock *BB, BasicBlock *IDom) { - ETNode *&BBNode = Nodes[BB]; - assert(!BBNode && "BasicBlock already in ET-Forest"); + // Otherwise, just loop through the basic block until we find Def or User. + BasicBlock::const_iterator I = DefBB->begin(); + for (; &*I != Def && &*I != UserInst; ++I) + /*empty*/; - BBNode = new ETNode(BB); - BBNode->setFather(getNode(IDom)); - DFSInfoValid = false; + return &*I != UserInst; } -void ETForestBase::setImmediateDominator(BasicBlock *BB, BasicBlock *newIDom) { - assert(getNode(BB) && "BasicBlock not in ET-Forest"); - assert(getNode(newIDom) && "IDom not in ET-Forest"); - - ETNode *Node = getNode(BB); - if (Node->hasFather()) { - if (Node->getFather()->getData() == newIDom) - return; - Node->Split(); - } - Node->setFather(getNode(newIDom)); - DFSInfoValid= false; -} +bool DominatorTree::isReachableFromEntry(const Use &U) const { + Instruction *I = dyn_cast(U.getUser()); -void ETForestBase::print(std::ostream &o, const Module *) const { - o << "=============================--------------------------------\n"; - o << "ET Forest:\n"; - o << "DFS Info "; - if (DFSInfoValid) - o << "is"; - else - o << "is not"; - o << " up to date\n"; + // ConstantExprs aren't really reachable from the entry block, but they + // don't need to be treated like unreachable code either. + if (!I) return true; - Function *F = getRoots()[0]->getParent(); - for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) { - o << " DFS Numbers For Basic Block:"; - WriteAsOperand(o, I, false); - o << " are:"; - if (ETNode *EN = getNode(I)) { - o << "In: " << EN->getDFSNumIn(); - o << " Out: " << EN->getDFSNumOut() << "\n"; - } else { - o << "No associated ETNode"; - } - o << "\n"; - } - o << "\n"; -} + // PHI nodes use their operands on their incoming edges. + if (PHINode *PN = dyn_cast(I)) + return isReachableFromEntry(PN->getIncomingBlock(U)); -void ETForestBase::dump() { - print (llvm::cerr); + // Everything else uses their operands in their own block. + return isReachableFromEntry(I->getParent()); }