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Diffstat (limited to 'include/llvm/Analysis/DominatorInternals.h')
| -rw-r--r-- | include/llvm/Analysis/DominatorInternals.h | 289 |
1 files changed, 0 insertions, 289 deletions
diff --git a/include/llvm/Analysis/DominatorInternals.h b/include/llvm/Analysis/DominatorInternals.h deleted file mode 100644 index c0f95cb..0000000 --- a/include/llvm/Analysis/DominatorInternals.h +++ /dev/null @@ -1,289 +0,0 @@ -//=== llvm/Analysis/DominatorInternals.h - Dominator Calculation -*- C++ -*-==// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// - -#ifndef LLVM_ANALYSIS_DOMINATOR_INTERNALS_H -#define LLVM_ANALYSIS_DOMINATOR_INTERNALS_H - -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/Analysis/Dominators.h" - -//===----------------------------------------------------------------------===// -// -// 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 the O(n*log(n)) versions of EVAL and LINK, because it turns -// out that the theoretically slower O(n*log(n)) implementation is actually -// faster than the almost-linear O(n*alpha(n)) version, even for large CFGs. -// -//===----------------------------------------------------------------------===// - -namespace llvm { - -template<class GraphT> -unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT, - typename GraphT::NodeType* V, 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 - InfoRec &VInfo = DT.Info[DT.Roots[i]]; - VInfo.DFSNum = VInfo.Semi = ++N; - VInfo.Label = V; - - Vertex.push_back(V); // Vertex[n] = V; - - for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) { - InfoRec &SuccVInfo = DT.Info[*SI]; - if (SuccVInfo.Semi == 0) { - SuccVInfo.Parent = V; - N = DTDFSPass(DT, *SI, N); - } - } -#else - bool IsChildOfArtificialExit = (N != 0); - - SmallVector<std::pair<typename GraphT::NodeType*, - typename GraphT::ChildIteratorType>, 32> Worklist; - Worklist.push_back(std::make_pair(V, GraphT::child_begin(V))); - while (!Worklist.empty()) { - typename GraphT::NodeType* BB = Worklist.back().first; - typename GraphT::ChildIteratorType NextSucc = Worklist.back().second; - - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &BBInfo = - DT.Info[BB]; - - // First time we visited this BB? - if (NextSucc == GraphT::child_begin(BB)) { - BBInfo.DFSNum = BBInfo.Semi = ++N; - BBInfo.Label = BB; - - DT.Vertex.push_back(BB); // Vertex[n] = V; - - if (IsChildOfArtificialExit) - BBInfo.Parent = 1; - - IsChildOfArtificialExit = false; - } - - // store the DFS number of the current BB - the reference to BBInfo might - // get invalidated when processing the successors. - unsigned BBDFSNum = BBInfo.DFSNum; - - // If we are done with this block, remove it from the worklist. - if (NextSucc == GraphT::child_end(BB)) { - Worklist.pop_back(); - continue; - } - - // 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. - typename GraphT::NodeType* Succ = *NextSucc; - - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &SuccVInfo = - DT.Info[Succ]; - if (SuccVInfo.Semi == 0) { - SuccVInfo.Parent = BBDFSNum; - Worklist.push_back(std::make_pair(Succ, GraphT::child_begin(Succ))); - } - } -#endif - return N; -} - -template<class GraphT> -typename GraphT::NodeType* -Eval(DominatorTreeBase<typename GraphT::NodeType>& DT, - typename GraphT::NodeType *VIn, unsigned LastLinked) { - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInInfo = - DT.Info[VIn]; - if (VInInfo.DFSNum < LastLinked) - return VIn; - - SmallVector<typename GraphT::NodeType*, 32> Work; - SmallPtrSet<typename GraphT::NodeType*, 32> Visited; - - if (VInInfo.Parent >= LastLinked) - Work.push_back(VIn); - - while (!Work.empty()) { - typename GraphT::NodeType* V = Work.back(); - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VInfo = - DT.Info[V]; - typename GraphT::NodeType* VAncestor = DT.Vertex[VInfo.Parent]; - - // Process Ancestor first - if (Visited.insert(VAncestor) && VInfo.Parent >= LastLinked) { - Work.push_back(VAncestor); - continue; - } - Work.pop_back(); - - // Update VInfo based on Ancestor info - if (VInfo.Parent < LastLinked) - continue; - - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &VAInfo = - DT.Info[VAncestor]; - typename GraphT::NodeType* VAncestorLabel = VAInfo.Label; - typename GraphT::NodeType* VLabel = VInfo.Label; - if (DT.Info[VAncestorLabel].Semi < DT.Info[VLabel].Semi) - VInfo.Label = VAncestorLabel; - VInfo.Parent = VAInfo.Parent; - } - - return VInInfo.Label; -} - -template<class FuncT, class NodeT> -void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT, - FuncT& F) { - typedef GraphTraits<NodeT> GraphT; - - unsigned N = 0; - bool MultipleRoots = (DT.Roots.size() > 1); - if (MultipleRoots) { - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &BBInfo = - DT.Info[NULL]; - BBInfo.DFSNum = BBInfo.Semi = ++N; - BBInfo.Label = NULL; - - DT.Vertex.push_back(NULL); // Vertex[n] = V; - } - - // Step #1: Number blocks in depth-first order and initialize variables used - // in later stages of the algorithm. - for (unsigned i = 0, e = static_cast<unsigned>(DT.Roots.size()); - i != e; ++i) - N = DFSPass<GraphT>(DT, DT.Roots[i], N); - - // it might be that some blocks did not get a DFS number (e.g., blocks of - // infinite loops). In these cases an artificial exit node is required. - MultipleRoots |= (DT.isPostDominator() && N != GraphTraits<FuncT*>::size(&F)); - - // When naively implemented, the Lengauer-Tarjan algorithm requires a separate - // bucket for each vertex. However, this is unnecessary, because each vertex - // is only placed into a single bucket (that of its semidominator), and each - // vertex's bucket is processed before it is added to any bucket itself. - // - // Instead of using a bucket per vertex, we use a single array Buckets that - // has two purposes. Before the vertex V with preorder number i is processed, - // Buckets[i] stores the index of the first element in V's bucket. After V's - // bucket is processed, Buckets[i] stores the index of the next element in the - // bucket containing V, if any. - SmallVector<unsigned, 32> Buckets; - Buckets.resize(N + 1); - for (unsigned i = 1; i <= N; ++i) - Buckets[i] = i; - - for (unsigned i = N; i >= 2; --i) { - typename GraphT::NodeType* W = DT.Vertex[i]; - typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo = - DT.Info[W]; - - // Step #2: Implicitly define the immediate dominator of vertices - for (unsigned j = i; Buckets[j] != i; j = Buckets[j]) { - typename GraphT::NodeType* V = DT.Vertex[Buckets[j]]; - typename GraphT::NodeType* U = Eval<GraphT>(DT, V, i + 1); - DT.IDoms[V] = DT.Info[U].Semi < i ? U : W; - } - - // Step #3: Calculate the semidominators of all vertices - - // initialize the semi dominator to point to the parent node - WInfo.Semi = WInfo.Parent; - typedef GraphTraits<Inverse<NodeT> > InvTraits; - for (typename InvTraits::ChildIteratorType CI = - InvTraits::child_begin(W), - E = InvTraits::child_end(W); CI != E; ++CI) { - typename InvTraits::NodeType *N = *CI; - if (DT.Info.count(N)) { // Only if this predecessor is reachable! - unsigned SemiU = DT.Info[Eval<GraphT>(DT, N, i + 1)].Semi; - if (SemiU < WInfo.Semi) - WInfo.Semi = SemiU; - } - } - - // If V is a non-root vertex and sdom(V) = parent(V), then idom(V) is - // necessarily parent(V). In this case, set idom(V) here and avoid placing - // V into a bucket. - if (WInfo.Semi == WInfo.Parent) { - DT.IDoms[W] = DT.Vertex[WInfo.Parent]; - } else { - Buckets[i] = Buckets[WInfo.Semi]; - Buckets[WInfo.Semi] = i; - } - } - - if (N >= 1) { - typename GraphT::NodeType* Root = DT.Vertex[1]; - for (unsigned j = 1; Buckets[j] != 1; j = Buckets[j]) { - typename GraphT::NodeType* V = DT.Vertex[Buckets[j]]; - DT.IDoms[V] = Root; - } - } - - // Step #4: Explicitly define the immediate dominator of each vertex - for (unsigned i = 2; i <= N; ++i) { - typename GraphT::NodeType* W = DT.Vertex[i]; - typename GraphT::NodeType*& WIDom = DT.IDoms[W]; - if (WIDom != DT.Vertex[DT.Info[W].Semi]) - WIDom = DT.IDoms[WIDom]; - } - - if (DT.Roots.empty()) return; - - // Add a node for the root. This node might be the actual root, if there is - // one exit block, or it may be the virtual exit (denoted by (BasicBlock *)0) - // which postdominates all real exits if there are multiple exit blocks, or - // an infinite loop. - typename GraphT::NodeType* Root = !MultipleRoots ? DT.Roots[0] : 0; - - DT.DomTreeNodes[Root] = DT.RootNode = - new DomTreeNodeBase<typename GraphT::NodeType>(Root, 0); - - // Loop over all of the reachable blocks in the function... - for (unsigned i = 2; i <= N; ++i) { - typename GraphT::NodeType* W = DT.Vertex[i]; - - DomTreeNodeBase<typename GraphT::NodeType> *BBNode = DT.DomTreeNodes[W]; - if (BBNode) continue; // Haven't calculated this node yet? - - typename GraphT::NodeType* ImmDom = DT.getIDom(W); - - assert(ImmDom || DT.DomTreeNodes[NULL]); - - // Get or calculate the node for the immediate dominator - DomTreeNodeBase<typename GraphT::NodeType> *IDomNode = - DT.getNodeForBlock(ImmDom); - - // Add a new tree node for this BasicBlock, and link it as a child of - // IDomNode - DomTreeNodeBase<typename GraphT::NodeType> *C = - new DomTreeNodeBase<typename GraphT::NodeType>(W, IDomNode); - DT.DomTreeNodes[W] = IDomNode->addChild(C); - } - - // Free temporary memory used to construct idom's - DT.IDoms.clear(); - DT.Info.clear(); - std::vector<typename GraphT::NodeType*>().swap(DT.Vertex); - - DT.updateDFSNumbers(); -} - -} - -#endif |