| //==- llvm/CodeGen/MachineDominators.h - Machine Dom Calculation -*- C++ -*-==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines classes mirroring those in llvm/Analysis/Dominators.h, |
| // but for target-specific code rather than target-independent IR. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_MACHINEDOMINATORS_H |
| #define LLVM_CODEGEN_MACHINEDOMINATORS_H |
| |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/CodeGen/MachineBasicBlock.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "llvm/Support/GenericDomTree.h" |
| #include "llvm/Support/GenericDomTreeConstruction.h" |
| #include <cassert> |
| #include <memory> |
| #include <vector> |
| |
| namespace llvm { |
| |
| template <> |
| inline void DominatorTreeBase<MachineBasicBlock, false>::addRoot( |
| MachineBasicBlock *MBB) { |
| this->Roots.push_back(MBB); |
| } |
| |
| extern template class DomTreeNodeBase<MachineBasicBlock>; |
| extern template class DominatorTreeBase<MachineBasicBlock, false>; // DomTree |
| extern template class DominatorTreeBase<MachineBasicBlock, true>; // PostDomTree |
| |
| using MachineDomTreeNode = DomTreeNodeBase<MachineBasicBlock>; |
| |
| //===------------------------------------- |
| /// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to |
| /// compute a normal dominator tree. |
| /// |
| class MachineDominatorTree : public MachineFunctionPass { |
| /// Helper structure used to hold all the basic blocks |
| /// involved in the split of a critical edge. |
| struct CriticalEdge { |
| MachineBasicBlock *FromBB; |
| MachineBasicBlock *ToBB; |
| MachineBasicBlock *NewBB; |
| }; |
| |
| /// Pile up all the critical edges to be split. |
| /// The splitting of a critical edge is local and thus, it is possible |
| /// to apply several of those changes at the same time. |
| mutable SmallVector<CriticalEdge, 32> CriticalEdgesToSplit; |
| |
| /// Remember all the basic blocks that are inserted during |
| /// edge splitting. |
| /// Invariant: NewBBs == all the basic blocks contained in the NewBB |
| /// field of all the elements of CriticalEdgesToSplit. |
| /// I.e., forall elt in CriticalEdgesToSplit, it exists BB in NewBBs |
| /// such as BB == elt.NewBB. |
| mutable SmallSet<MachineBasicBlock *, 32> NewBBs; |
| |
| /// The DominatorTreeBase that is used to compute a normal dominator tree |
| std::unique_ptr<DomTreeBase<MachineBasicBlock>> DT; |
| |
| /// Apply all the recorded critical edges to the DT. |
| /// This updates the underlying DT information in a way that uses |
| /// the fast query path of DT as much as possible. |
| /// |
| /// \post CriticalEdgesToSplit.empty(). |
| void applySplitCriticalEdges() const; |
| |
| public: |
| static char ID; // Pass ID, replacement for typeid |
| |
| MachineDominatorTree(); |
| |
| DomTreeBase<MachineBasicBlock> &getBase() { |
| if (!DT) DT.reset(new DomTreeBase<MachineBasicBlock>()); |
| applySplitCriticalEdges(); |
| return *DT; |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| /// 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). |
| /// |
| inline const SmallVectorImpl<MachineBasicBlock*> &getRoots() const { |
| applySplitCriticalEdges(); |
| return DT->getRoots(); |
| } |
| |
| inline MachineBasicBlock *getRoot() const { |
| applySplitCriticalEdges(); |
| return DT->getRoot(); |
| } |
| |
| inline MachineDomTreeNode *getRootNode() const { |
| applySplitCriticalEdges(); |
| return DT->getRootNode(); |
| } |
| |
| bool runOnMachineFunction(MachineFunction &F) override; |
| |
| inline bool dominates(const MachineDomTreeNode* A, |
| const MachineDomTreeNode* B) const { |
| applySplitCriticalEdges(); |
| return DT->dominates(A, B); |
| } |
| |
| inline bool dominates(const MachineBasicBlock* A, |
| const MachineBasicBlock* B) const { |
| applySplitCriticalEdges(); |
| return DT->dominates(A, B); |
| } |
| |
| // dominates - Return true if A dominates B. This performs the |
| // special checks necessary if A and B are in the same basic block. |
| bool dominates(const MachineInstr *A, const MachineInstr *B) const { |
| applySplitCriticalEdges(); |
| const MachineBasicBlock *BBA = A->getParent(), *BBB = B->getParent(); |
| if (BBA != BBB) return DT->dominates(BBA, BBB); |
| |
| // Loop through the basic block until we find A or B. |
| MachineBasicBlock::const_iterator I = BBA->begin(); |
| for (; &*I != A && &*I != B; ++I) |
| /*empty*/ ; |
| |
| //if(!DT.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; |
| //} |
| } |
| |
| inline bool properlyDominates(const MachineDomTreeNode* A, |
| const MachineDomTreeNode* B) const { |
| applySplitCriticalEdges(); |
| return DT->properlyDominates(A, B); |
| } |
| |
| inline bool properlyDominates(const MachineBasicBlock* A, |
| const MachineBasicBlock* B) const { |
| applySplitCriticalEdges(); |
| return DT->properlyDominates(A, B); |
| } |
| |
| /// findNearestCommonDominator - Find nearest common dominator basic block |
| /// for basic block A and B. If there is no such block then return NULL. |
| inline MachineBasicBlock *findNearestCommonDominator(MachineBasicBlock *A, |
| MachineBasicBlock *B) { |
| applySplitCriticalEdges(); |
| return DT->findNearestCommonDominator(A, B); |
| } |
| |
| inline MachineDomTreeNode *operator[](MachineBasicBlock *BB) const { |
| applySplitCriticalEdges(); |
| return DT->getNode(BB); |
| } |
| |
| /// getNode - return the (Post)DominatorTree node for the specified basic |
| /// block. This is the same as using operator[] on this class. |
| /// |
| inline MachineDomTreeNode *getNode(MachineBasicBlock *BB) const { |
| applySplitCriticalEdges(); |
| return DT->getNode(BB); |
| } |
| |
| /// addNewBlock - 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. |
| inline MachineDomTreeNode *addNewBlock(MachineBasicBlock *BB, |
| MachineBasicBlock *DomBB) { |
| applySplitCriticalEdges(); |
| return DT->addNewBlock(BB, DomBB); |
| } |
| |
| /// changeImmediateDominator - This method is used to update the dominator |
| /// tree information when a node's immediate dominator changes. |
| /// |
| inline void changeImmediateDominator(MachineBasicBlock *N, |
| MachineBasicBlock* NewIDom) { |
| applySplitCriticalEdges(); |
| DT->changeImmediateDominator(N, NewIDom); |
| } |
| |
| inline void changeImmediateDominator(MachineDomTreeNode *N, |
| MachineDomTreeNode* NewIDom) { |
| applySplitCriticalEdges(); |
| DT->changeImmediateDominator(N, NewIDom); |
| } |
| |
| /// 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. |
| inline void eraseNode(MachineBasicBlock *BB) { |
| applySplitCriticalEdges(); |
| DT->eraseNode(BB); |
| } |
| |
| /// splitBlock - BB is split and now it has one successor. Update dominator |
| /// tree to reflect this change. |
| inline void splitBlock(MachineBasicBlock* NewBB) { |
| applySplitCriticalEdges(); |
| DT->splitBlock(NewBB); |
| } |
| |
| /// isReachableFromEntry - Return true if A is dominated by the entry |
| /// block of the function containing it. |
| bool isReachableFromEntry(const MachineBasicBlock *A) { |
| applySplitCriticalEdges(); |
| return DT->isReachableFromEntry(A); |
| } |
| |
| void releaseMemory() override; |
| |
| void verifyAnalysis() const override; |
| |
| void print(raw_ostream &OS, const Module*) const override; |
| |
| /// Record that the critical edge (FromBB, ToBB) has been |
| /// split with NewBB. |
| /// This is best to use this method instead of directly update the |
| /// underlying information, because this helps mitigating the |
| /// number of time the DT information is invalidated. |
| /// |
| /// \note Do not use this method with regular edges. |
| /// |
| /// \note To benefit from the compile time improvement incurred by this |
| /// method, the users of this method have to limit the queries to the DT |
| /// interface between two edges splitting. In other words, they have to |
| /// pack the splitting of critical edges as much as possible. |
| void recordSplitCriticalEdge(MachineBasicBlock *FromBB, |
| MachineBasicBlock *ToBB, |
| MachineBasicBlock *NewBB) { |
| bool Inserted = NewBBs.insert(NewBB).second; |
| (void)Inserted; |
| assert(Inserted && |
| "A basic block inserted via edge splitting cannot appear twice"); |
| CriticalEdgesToSplit.push_back({FromBB, ToBB, NewBB}); |
| } |
| }; |
| |
| //===------------------------------------- |
| /// DominatorTree GraphTraits specialization so the DominatorTree can be |
| /// iterable by generic graph iterators. |
| /// |
| |
| template <class Node, class ChildIterator> |
| struct MachineDomTreeGraphTraitsBase { |
| using NodeRef = Node *; |
| using ChildIteratorType = ChildIterator; |
| |
| static NodeRef getEntryNode(NodeRef N) { return N; } |
| static ChildIteratorType child_begin(NodeRef N) { return N->begin(); } |
| static ChildIteratorType child_end(NodeRef N) { return N->end(); } |
| }; |
| |
| template <class T> struct GraphTraits; |
| |
| template <> |
| struct GraphTraits<MachineDomTreeNode *> |
| : public MachineDomTreeGraphTraitsBase<MachineDomTreeNode, |
| MachineDomTreeNode::iterator> {}; |
| |
| template <> |
| struct GraphTraits<const MachineDomTreeNode *> |
| : public MachineDomTreeGraphTraitsBase<const MachineDomTreeNode, |
| MachineDomTreeNode::const_iterator> { |
| }; |
| |
| template <> struct GraphTraits<MachineDominatorTree*> |
| : public GraphTraits<MachineDomTreeNode *> { |
| static NodeRef getEntryNode(MachineDominatorTree *DT) { |
| return DT->getRootNode(); |
| } |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_CODEGEN_MACHINEDOMINATORS_H |