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//===- Dominators.h - Dominator Info Calculation ----------------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines the DominatorTree class, which provides fast and efficient
// dominance queries.
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Function.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/GenericDomTree.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
namespace llvm {
EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
#define LLVM_COMMA ,
DominatorTreeBase<GraphTraits<BasicBlock *>::NodeType> &DT LLVM_COMMA
Function &F));
void Calculate<Function LLVM_COMMA Inverse<BasicBlock *> >(
DominatorTreeBase<GraphTraits<Inverse<BasicBlock *> >::NodeType> &DT
LLVM_COMMA Function &F));
typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
class BasicBlockEdge {
const BasicBlock *Start;
const BasicBlock *End;
BasicBlockEdge(const BasicBlock *Start_, const BasicBlock *End_) :
Start(Start_), End(End_) { }
const BasicBlock *getStart() const {
return Start;
const BasicBlock *getEnd() const {
return End;
bool isSingleEdge() const;
/// \brief Concrete subclass of DominatorTreeBase that is used to compute a
/// normal dominator tree.
class DominatorTree : public DominatorTreeBase<BasicBlock> {
typedef DominatorTreeBase<BasicBlock> Base;
DominatorTree() : DominatorTreeBase<BasicBlock>(false) {}
/// \brief Returns *false* if the other dominator tree matches this dominator
/// tree.
inline bool compare(const DominatorTree &Other) const {
const DomTreeNode *R = getRootNode();
const DomTreeNode *OtherR = Other.getRootNode();
if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
return true;
if (Base::compare(Other))
return true;
return false;
// Ensure base-class overloads are visible.
using Base::dominates;
/// \brief 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 dominates(const Instruction *Def, const Use &U) const;
bool dominates(const Instruction *Def, const Instruction *User) const;
bool dominates(const Instruction *Def, const BasicBlock *BB) const;
bool dominates(const BasicBlockEdge &BBE, const Use &U) const;
bool dominates(const BasicBlockEdge &BBE, const BasicBlock *BB) const;
// Ensure base class overloads are visible.
using Base::isReachableFromEntry;
/// \brief Provide an overload for a Use.
bool isReachableFromEntry(const Use &U) const;
/// \brief Verify the correctness of the domtree by re-computing it.
/// This should only be used for debugging as it aborts the program if the
/// verification fails.
void verifyDomTree() const;
// DominatorTree GraphTraits specializations so the DominatorTree can be
// iterable by generic graph iterators.
template <> struct GraphTraits<DomTreeNode*> {
typedef DomTreeNode NodeType;
typedef NodeType::iterator ChildIteratorType;
static NodeType *getEntryNode(NodeType *N) {
return N;
static inline ChildIteratorType child_begin(NodeType *N) {
return N->begin();
static inline ChildIteratorType child_end(NodeType *N) {
return N->end();
typedef df_iterator<DomTreeNode*> nodes_iterator;
static nodes_iterator nodes_begin(DomTreeNode *N) {
return df_begin(getEntryNode(N));
static nodes_iterator nodes_end(DomTreeNode *N) {
return df_end(getEntryNode(N));
template <> struct GraphTraits<DominatorTree*>
: public GraphTraits<DomTreeNode*> {
static NodeType *getEntryNode(DominatorTree *DT) {
return DT->getRootNode();
static nodes_iterator nodes_begin(DominatorTree *N) {
return df_begin(getEntryNode(N));
static nodes_iterator nodes_end(DominatorTree *N) {
return df_end(getEntryNode(N));
/// \brief Analysis pass which computes a \c DominatorTree.
class DominatorTreeWrapperPass : public FunctionPass {
DominatorTree DT;
static char ID;
DominatorTreeWrapperPass() : FunctionPass(ID) {
DominatorTree &getDomTree() { return DT; }
const DominatorTree &getDomTree() const { return DT; }
bool runOnFunction(Function &F) override;
void verifyAnalysis() const override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
void releaseMemory() override { DT.releaseMemory(); }
void print(raw_ostream &OS, const Module *M = nullptr) const override;
} // End llvm namespace