//===- GenericDomTree.h - Generic dominator trees for graphs ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines a set of templates that efficiently compute a dominator
/// tree over a generic graph. This is used typically in LLVM for fast
/// dominance queries on the CFG, but is fully generic w.r.t. the underlying
/// graph types.
///
/// Unlike ADT/* graph algorithms, generic dominator tree has more requirements
/// on the graph's NodeRef. The NodeRef should be a pointer and, depending on
/// the implementation, e.g. NodeRef->getParent() return the parent node.
///
/// FIXME: Maybe GenericDomTree needs a TreeTraits, instead of GraphTraits.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_GENERICDOMTREE_H
#define LLVM_SUPPORT_GENERICDOMTREE_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <iterator>
#include <memory>
#include <type_traits>
#include <utility>
#include <vector>
namespace llvm {
template <class NodeT> class DominatorTreeBase;
namespace detail {
template <typename GT> struct DominatorTreeBaseTraits {
static_assert(std::is_pointer<typename GT::NodeRef>::value,
"Currently NodeRef must be a pointer type.");
using type = DominatorTreeBase<
typename std::remove_pointer<typename GT::NodeRef>::type>;
};
} // end namespace detail
template <typename GT>
using DominatorTreeBaseByGraphTraits =
typename detail::DominatorTreeBaseTraits<GT>::type;
/// \brief Base class that other, more interesting dominator analyses
/// inherit from.
template <class NodeT> class DominatorBase {
protected:
std::vector<NodeT *> Roots;
bool IsPostDominators;
explicit DominatorBase(bool isPostDom)
: Roots(), IsPostDominators(isPostDom) {}
DominatorBase(DominatorBase &&Arg)
: Roots(std::move(Arg.Roots)),
IsPostDominators(std::move(Arg.IsPostDominators)) {
Arg.Roots.clear();
}
DominatorBase &operator=(DominatorBase &&RHS) {
Roots = std::move(RHS.Roots);
IsPostDominators = std::move(RHS.IsPostDominators);
RHS.Roots.clear();
return *this;
}
public:
/// getRoots - Return the root blocks of the current CFG. This may include
/// multiple blocks if we are computing post dominators. For forward
/// dominators, this will always be a single block (the entry node).
///
const std::vector<NodeT *> &getRoots() const { return Roots; }
/// isPostDominator - Returns true if analysis based of postdoms
///
bool isPostDominator() const { return IsPostDominators; }
};
/// \brief Base class for the actual dominator tree node.
template <class NodeT> class DomTreeNodeBase {
friend struct PostDominatorTree;
template <class N> friend class DominatorTreeBase;
NodeT *TheBB;
DomTreeNodeBase<NodeT> *IDom;
std::vector<DomTreeNodeBase<NodeT> *> Children;
mutable int DFSNumIn = -1;
mutable int DFSNumOut = -1;
public:
DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
: TheBB(BB), IDom(iDom) {}
typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator
const_iterator;
iterator begin() { return Children.begin(); }
iterator end() { return Children.end(); }
const_iterator begin() const { return Children.begin(); }
const_iterator end() const { return Children.end(); }
NodeT *getBlock() const { return TheBB; }
DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
const std::vector<DomTreeNodeBase<NodeT> *> &getChildren() const {
return Children;
}
std::unique_ptr<DomTreeNodeBase<NodeT>>
addChild(std::unique_ptr<DomTreeNodeBase<NodeT>> C) {
Children.push_back(C.get());
return C;
}
size_t getNumChildren() const { return Children.size(); }
void clearAllChildren() { Children.clear(); }
bool compare(const DomTreeNodeBase<NodeT> *Other) const {
if (getNumChildren() != Other->getNumChildren())
return true;
SmallPtrSet<const NodeT *, 4> OtherChildren;
for (const DomTreeNodeBase *I : *Other) {
const NodeT *Nd = I->getBlock();
OtherChildren.insert(Nd);
}
for (const DomTreeNodeBase *I : *this) {
const NodeT *N = I->getBlock();
if (OtherChildren.count(N) == 0)
return true;
}
return false;
}
void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
assert(IDom && "No immediate dominator?");
if (IDom != NewIDom) {
typename std::vector<DomTreeNodeBase<NodeT> *>::iterator I =
find(IDom->Children, 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);
}
}
/// getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes
/// in the dominator tree. They are only guaranteed valid if
/// updateDFSNumbers() has been called.
unsigned getDFSNumIn() const { return DFSNumIn; }
unsigned getDFSNumOut() const { return DFSNumOut; }
private:
// Return true if this node is dominated by other. Use this only if DFS info
// is valid.
bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
return this->DFSNumIn >= other->DFSNumIn &&
this->DFSNumOut <= other->DFSNumOut;
}
};
template <class NodeT>
raw_ostream &operator<<(raw_ostream &o, const DomTreeNodeBase<NodeT> *Node) {
if (Node->getBlock())
Node->getBlock()->printAsOperand(o, false);
else
o << " <<exit node>>";
o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
return o << "\n";
}
template <class NodeT>
void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &o,
unsigned Lev) {
o.indent(2 * Lev) << "[" << Lev << "] " << N;
for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
E = N->end();
I != E; ++I)
PrintDomTree<NodeT>(*I, o, Lev + 1);
}
// The calculate routine is provided in a separate header but referenced here.
template <class FuncT, class N>
void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT, FuncT &F);
/// \brief Core dominator tree base class.
///
/// This class is a generic template over graph nodes. It is instantiated for
/// various graphs in the LLVM IR or in the code generator.
template <class NodeT> class DominatorTreeBase : public DominatorBase<NodeT> {
bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
assert(A != B);
assert(isReachableFromEntry(B));
assert(isReachableFromEntry(A));
const DomTreeNodeBase<NodeT> *IDom;
while ((IDom = B->getIDom()) != nullptr && IDom != A && IDom != B)
B = IDom; // Walk up the tree
return IDom != nullptr;
}
/// \brief Wipe this tree's state without releasing any resources.
///
/// This is essentially a post-move helper only. It leaves the object in an
/// assignable and destroyable state, but otherwise invalid.
void wipe() {
DomTreeNodes.clear();
IDoms.clear();
Vertex.clear();
Info.clear();
RootNode = nullptr;
}
protected:
typedef DenseMap<NodeT *, std::unique_ptr<DomTreeNodeBase<NodeT>>>
DomTreeNodeMapType;
DomTreeNodeMapType DomTreeNodes;
DomTreeNodeBase<NodeT> *RootNode;
mutable bool DFSInfoValid = false;
mutable unsigned int SlowQueries = 0;
// Information record used during immediate dominators computation.
struct InfoRec {
unsigned DFSNum = 0;
unsigned Parent = 0;
unsigned Semi = 0;
NodeT *Label = nullptr;
InfoRec() = default;
};
DenseMap<NodeT *, NodeT *> IDoms;
// Vertex - Map the DFS number to the NodeT*
std::vector<NodeT *> Vertex;
// Info - Collection of information used during the computation of idoms.
DenseMap<NodeT *, InfoRec> Info;
void reset() {
DomTreeNodes.clear();
IDoms.clear();
this->Roots.clear();
Vertex.clear();
RootNode = nullptr;
DFSInfoValid = false;
SlowQueries = 0;
}
// NewBB is split and now it has one successor. Update dominator tree to
// reflect this change.
template <class N>
void Split(typename GraphTraits<N>::NodeRef NewBB) {
using GraphT = GraphTraits<N>;
using NodeRef = typename GraphT::NodeRef;
assert(std::distance(GraphT::child_begin(NewBB),
GraphT::child_end(NewBB)) == 1 &&
"NewBB should have a single successor!");
NodeRef NewBBSucc = *GraphT::child_begin(NewBB);
std::vector<NodeRef> PredBlocks;
for (const auto &Pred : children<Inverse<N>>(NewBB))
PredBlocks.push_back(Pred);
assert(!PredBlocks.empty() && "No predblocks?");
bool NewBBDominatesNewBBSucc = true;
for (const auto &Pred : children<Inverse<N>>(NewBBSucc)) {
if (Pred != NewBB && !dominates(NewBBSucc, Pred) &&
isReachableFromEntry(Pred)) {
NewBBDominatesNewBBSucc = false;
break;
}
}
// Find NewBB's immediate dominator and create new dominator tree node for
// NewBB.
NodeT *NewBBIDom = nullptr;
unsigned i = 0;
for (i = 0; i < PredBlocks.size(); ++i)
if (isReachableFromEntry(PredBlocks[i])) {
NewBBIDom = PredBlocks[i];
break;
}
// It's possible that none of the predecessors of NewBB are reachable;
// in that case, NewBB itself is unreachable, so nothing needs to be
// changed.
if (!NewBBIDom)
return;
for (i = i + 1; i < PredBlocks.size(); ++i) {
if (isReachableFromEntry(PredBlocks[i]))
NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
}
// Create the new dominator tree node... and set the idom of NewBB.
DomTreeNodeBase<NodeT> *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) {
DomTreeNodeBase<NodeT> *NewBBSuccNode = getNode(NewBBSucc);
changeImmediateDominator(NewBBSuccNode, NewBBNode);
}
}
public:
explicit DominatorTreeBase(bool isPostDom)
: DominatorBase<NodeT>(isPostDom) {}
DominatorTreeBase(DominatorTreeBase &&Arg)
: DominatorBase<NodeT>(
std::move(static_cast<DominatorBase<NodeT> &>(Arg))),
DomTreeNodes(std::move(Arg.DomTreeNodes)),
RootNode(std::move(Arg.RootNode)),
DFSInfoValid(std::move(Arg.DFSInfoValid)),
SlowQueries(std::move(Arg.SlowQueries)), IDoms(std::move(Arg.IDoms)),
Vertex(std::move(Arg.Vertex)), Info(std::move(Arg.Info)) {
Arg.wipe();
}
DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
DominatorBase<NodeT>::operator=(
std::move(static_cast<DominatorBase<NodeT> &>(RHS)));
DomTreeNodes = std::move(RHS.DomTreeNodes);
RootNode = std::move(RHS.RootNode);
DFSInfoValid = std::move(RHS.DFSInfoValid);
SlowQueries = std::move(RHS.SlowQueries);
IDoms = std::move(RHS.IDoms);
Vertex = std::move(RHS.Vertex);
Info = std::move(RHS.Info);
RHS.wipe();
return *this;
}
DominatorTreeBase(const DominatorTreeBase &) = delete;
DominatorTreeBase &operator=(const DominatorTreeBase &) = delete;
/// compare - Return false if the other dominator tree base matches this
/// dominator tree base. Otherwise return true.
bool compare(const DominatorTreeBase &Other) const {
const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
if (DomTreeNodes.size() != OtherDomTreeNodes.size())
return true;
for (const auto &DomTreeNode : DomTreeNodes) {
NodeT *BB = DomTreeNode.first;
typename DomTreeNodeMapType::const_iterator OI =
OtherDomTreeNodes.find(BB);
if (OI == OtherDomTreeNodes.end())
return true;
DomTreeNodeBase<NodeT> &MyNd = *DomTreeNode.second;
DomTreeNodeBase<NodeT> &OtherNd = *OI->second;
if (MyNd.compare(&OtherNd))
return true;
}
return false;
}
void releaseMemory() { reset(); }
/// getNode - return the (Post)DominatorTree node for the specified basic
/// block. This is the same as using operator[] on this class. The result
/// may (but is not required to) be null for a forward (backwards)
/// statically unreachable block.
DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
auto I = DomTreeNodes.find(BB);
if (I != DomTreeNodes.end())
return I->second.get();
return nullptr;
}
/// See getNode.
DomTreeNodeBase<NodeT> *operator[](NodeT *BB) const { return getNode(BB); }
/// getRootNode - This returns the entry node for the CFG of the function. If
/// this tree represents the post-dominance relations for a function, however,
/// this root may be a node with the block == NULL. This is the case when
/// there are multiple exit nodes from a particular function. Consumers of
/// post-dominance information must be capable of dealing with this
/// possibility.
///
DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
/// Get all nodes dominated by R, including R itself.
void getDescendants(NodeT *R, SmallVectorImpl<NodeT *> &Result) const {
Result.clear();
const DomTreeNodeBase<NodeT> *RN = getNode(R);
if (!RN)
return; // If R is unreachable, it will not be present in the DOM tree.
SmallVector<const DomTreeNodeBase<NodeT> *, 8> WL;
WL.push_back(RN);
while (!WL.empty()) {
const DomTreeNodeBase<NodeT> *N = WL.pop_back_val();
Result.push_back(N->getBlock());
WL.append(N->begin(), N->end());
}
}
/// properlyDominates - Returns true iff A dominates B and A != B.
/// Note that this is not a constant time operation!
///
bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
if (!A || !B)
return false;
if (A == B)
return false;
return dominates(A, B);
}
bool properlyDominates(const NodeT *A, const NodeT *B) const;
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
bool isReachableFromEntry(const NodeT *A) const {
assert(!this->isPostDominator() &&
"This is not implemented for post dominators");
return isReachableFromEntry(getNode(const_cast<NodeT *>(A)));
}
bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { return A; }
/// dominates - Returns true iff A dominates B. Note that this is not a
/// constant time operation!
///
bool dominates(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
// A node trivially dominates itself.
if (B == A)
return true;
// An unreachable node is dominated by anything.
if (!isReachableFromEntry(B))
return true;
// And dominates nothing.
if (!isReachableFromEntry(A))
return false;
// Compare the result of the tree walk and the dfs numbers, if expensive
// checks are enabled.
#ifdef EXPENSIVE_CHECKS
assert((!DFSInfoValid ||
(dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&
"Tree walk disagrees with dfs numbers!");
#endif
if (DFSInfoValid)
return B->DominatedBy(A);
// If we end up with too many slow queries, just update the
// DFS numbers on the theory that we are going to keep querying.
SlowQueries++;
if (SlowQueries > 32) {
updateDFSNumbers();
return B->DominatedBy(A);
}
return dominatedBySlowTreeWalk(A, B);
}
bool dominates(const NodeT *A, const NodeT *B) const;
NodeT *getRoot() const {
assert(this->Roots.size() == 1 && "Should always have entry node!");
return this->Roots[0];
}
/// findNearestCommonDominator - Find nearest common dominator basic block
/// for basic block A and B. If there is no such block then return NULL.
NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
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
// (for forward-dominators).
if (!this->isPostDominator()) {
NodeT &Entry = A->getParent()->front();
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;
DomTreeNodeBase<NodeT> *NodeA = getNode(A);
DomTreeNodeBase<NodeT> *NodeB = getNode(B);
// If we have DFS info, then we can avoid all allocations by just querying
// it from each IDom. Note that because we call 'dominates' twice above, we
// expect to call through this code at most 16 times in a row without
// building valid DFS information. This is important as below is a *very*
// slow tree walk.
if (DFSInfoValid) {
DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
while (IDomA) {
if (NodeB->DominatedBy(IDomA))
return IDomA->getBlock();
IDomA = IDomA->getIDom();
}
return nullptr;
}
// Collect NodeA dominators set.
SmallPtrSet<DomTreeNodeBase<NodeT> *, 16> NodeADoms;
NodeADoms.insert(NodeA);
DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
while (IDomA) {
NodeADoms.insert(IDomA);
IDomA = IDomA->getIDom();
}
// Walk NodeB immediate dominators chain and find common dominator node.
DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
while (IDomB) {
if (NodeADoms.count(IDomB) != 0)
return IDomB->getBlock();
IDomB = IDomB->getIDom();
}
return nullptr;
}
const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) {
// Cast away the const qualifiers here. This is ok since
// const is re-introduced on the return type.
return findNearestCommonDominator(const_cast<NodeT *>(A),
const_cast<NodeT *>(B));
}
//===--------------------------------------------------------------------===//
// API to update (Post)DominatorTree information based on modifications to
// the CFG...
/// Add a new node to the dominator tree information.
///
/// This creates a new node as a child of DomBB dominator node, linking it
/// into the children list of the immediate dominator.
///
/// \param BB New node in CFG.
/// \param DomBB CFG node that is dominator for BB.
/// \returns New dominator tree node that represents new CFG node.
///
DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
assert(getNode(BB) == nullptr && "Block already in dominator tree!");
DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
assert(IDomNode && "Not immediate dominator specified for block!");
DFSInfoValid = false;
return (DomTreeNodes[BB] = IDomNode->addChild(
llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode))).get();
}
/// Add a new node to the forward dominator tree and make it a new root.
///
/// \param BB New node in CFG.
/// \returns New dominator tree node that represents new CFG node.
///
DomTreeNodeBase<NodeT> *setNewRoot(NodeT *BB) {
assert(getNode(BB) == nullptr && "Block already in dominator tree!");
assert(!this->isPostDominator() &&
"Cannot change root of post-dominator tree");
DFSInfoValid = false;
auto &Roots = DominatorBase<NodeT>::Roots;
DomTreeNodeBase<NodeT> *NewNode = (DomTreeNodes[BB] =
llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, nullptr)).get();
if (Roots.empty()) {
addRoot(BB);
} else {
assert(Roots.size() == 1);
NodeT *OldRoot = Roots.front();
DomTreeNodes[OldRoot] =
NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
Roots[0] = BB;
}
return RootNode = NewNode;
}
/// changeImmediateDominator - This method is used to update the dominator
/// tree information when a node's immediate dominator changes.
///
void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
DomTreeNodeBase<NodeT> *NewIDom) {
assert(N && NewIDom && "Cannot change null node pointers!");
DFSInfoValid = false;
N->setIDom(NewIDom);
}
void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
changeImmediateDominator(getNode(BB), getNode(NewBB));
}
/// eraseNode - Removes a node from the dominator tree. Block must not
/// dominate any other blocks. Removes node from its immediate dominator's
/// children list. Deletes dominator node associated with basic block BB.
void eraseNode(NodeT *BB) {
DomTreeNodeBase<NodeT> *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.
DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
if (IDom) {
typename std::vector<DomTreeNodeBase<NodeT> *>::iterator I =
find(IDom->Children, 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);
}
/// splitBlock - BB is split and now it has one successor. Update dominator
/// tree to reflect this change.
void splitBlock(NodeT *NewBB) {
if (this->IsPostDominators)
Split<Inverse<NodeT *>>(NewBB);
else
Split<NodeT *>(NewBB);
}
/// print - Convert to human readable form
///
void print(raw_ostream &o) const {
o << "=============================--------------------------------\n";
if (this->isPostDominator())
o << "Inorder PostDominator Tree: ";
else
o << "Inorder Dominator Tree: ";
if (!DFSInfoValid)
o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
o << "\n";
// The postdom tree can have a null root if there are no returns.
if (getRootNode())
PrintDomTree<NodeT>(getRootNode(), o, 1);
}
protected:
template <class GraphT>
friend typename GraphT::NodeRef
Eval(DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
unsigned LastLinked);
template <class GraphT>
friend unsigned ReverseDFSPass(DominatorTreeBaseByGraphTraits<GraphT> &DT,
typename GraphT::NodeRef V, unsigned N);
template <class GraphT>
friend unsigned DFSPass(DominatorTreeBaseByGraphTraits<GraphT> &DT,
typename GraphT::NodeRef V, unsigned N);
template <class FuncT, class N>
friend void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT,
FuncT &F);
DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
if (DomTreeNodeBase<NodeT> *Node = getNode(BB))
return Node;
// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
NodeT *IDom = getIDom(BB);
assert(IDom || DomTreeNodes[nullptr]);
DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
// Add a new tree node for this NodeT, and link it as a child of
// IDomNode
return (DomTreeNodes[BB] = IDomNode->addChild(
llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode))).get();
}
NodeT *getIDom(NodeT *BB) const { return IDoms.lookup(BB); }
void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
public:
/// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
/// dominator tree in dfs order.
void updateDFSNumbers() const {
if (DFSInfoValid) {
SlowQueries = 0;
return;
}
unsigned DFSNum = 0;
SmallVector<std::pair<const DomTreeNodeBase<NodeT> *,
typename DomTreeNodeBase<NodeT>::const_iterator>,
32> WorkStack;
const DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
if (!ThisRoot)
return;
// Even in the case of multiple exits that form the post dominator root
// nodes, do not iterate over all exits, but start from the virtual root
// node. Otherwise bbs, that are not post dominated by any exit but by the
// virtual root node, will never be assigned a DFS number.
WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
ThisRoot->DFSNumIn = DFSNum++;
while (!WorkStack.empty()) {
const DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
typename DomTreeNodeBase<NodeT>::const_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.
const DomTreeNodeBase<NodeT> *Child = *ChildIt;
++WorkStack.back().second;
WorkStack.push_back(std::make_pair(Child, Child->begin()));
Child->DFSNumIn = DFSNum++;
}
}
SlowQueries = 0;
DFSInfoValid = true;
}
/// recalculate - compute a dominator tree for the given function
template <class FT> void recalculate(FT &F) {
typedef GraphTraits<FT *> TraitsTy;
reset();
Vertex.push_back(nullptr);
if (!this->IsPostDominators) {
// Initialize root
NodeT *entry = TraitsTy::getEntryNode(&F);
addRoot(entry);
Calculate<FT, NodeT *>(*this, F);
} else {
// Initialize the roots list
for (auto *Node : nodes(&F))
if (TraitsTy::child_begin(Node) == TraitsTy::child_end(Node))
addRoot(Node);
Calculate<FT, Inverse<NodeT *>>(*this, F);
}
}
};
// These two functions are declared out of line as a workaround for building
// with old (< r147295) versions of clang because of pr11642.
template <class NodeT>
bool DominatorTreeBase<NodeT>::dominates(const NodeT *A, const NodeT *B) const {
if (A == B)
return true;
// Cast away the const qualifiers here. This is ok since
// this function doesn't actually return the values returned
// from getNode.
return dominates(getNode(const_cast<NodeT *>(A)),
getNode(const_cast<NodeT *>(B)));
}
template <class NodeT>
bool DominatorTreeBase<NodeT>::properlyDominates(const NodeT *A,
const NodeT *B) const {
if (A == B)
return false;
// Cast away the const qualifiers here. This is ok since
// this function doesn't actually return the values returned
// from getNode.
return dominates(getNode(const_cast<NodeT *>(A)),
getNode(const_cast<NodeT *>(B)));
}
} // end namespace llvm
#endif // LLVM_SUPPORT_GENERICDOMTREE_H