llvm-6502/include/llvm/CodeGen/MachineDominators.h
David Blaikie 5401ba7099 Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>
This is to be consistent with StringSet and ultimately with the standard
library's associative container insert function.

This lead to updating SmallSet::insert to return pair<iterator, bool>,
and then to update SmallPtrSet::insert to return pair<iterator, bool>,
and then to update all the existing users of those functions...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222334 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-19 07:49:26 +00:00

346 lines
12 KiB
C++

//=- llvm/CodeGen/MachineDominators.h - Machine Dom 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 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/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/GenericDomTree.h"
#include "llvm/Support/GenericDomTreeConstruction.h"
namespace llvm {
template<>
inline void DominatorTreeBase<MachineBasicBlock>::addRoot(MachineBasicBlock* MBB) {
this->Roots.push_back(MBB);
}
EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<MachineBasicBlock>);
typedef DomTreeNodeBase<MachineBasicBlock> MachineDomTreeNode;
//===-------------------------------------
/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
/// compute a normal dominator tree.
///
class MachineDominatorTree : public MachineFunctionPass {
/// \brief 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;
CriticalEdge(MachineBasicBlock *FromBB, MachineBasicBlock *ToBB,
MachineBasicBlock *NewBB)
: FromBB(FromBB), ToBB(ToBB), NewBB(NewBB) {}
};
/// \brief 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;
/// \brief 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;
/// \brief 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 {
// Bail out early if there is nothing to do.
if (CriticalEdgesToSplit.empty())
return;
// For each element in CriticalEdgesToSplit, remember whether or
// not element is the new immediate domminator of its successor.
// The mapping is done by index, i.e., the information for the ith
// element of CriticalEdgesToSplit is the ith element of IsNewIDom.
SmallVector<bool, 32> IsNewIDom;
IsNewIDom.resize(CriticalEdgesToSplit.size());
size_t Idx = 0;
// Collect all the dominance properties info, before invalidating
// the underlying DT.
for (CriticalEdge &Edge : CriticalEdgesToSplit) {
// Update dominator information.
MachineBasicBlock *Succ = Edge.ToBB;
MachineDomTreeNode *SucccDTNode = DT->getNode(Succ);
IsNewIDom[Idx] = true;
for (MachineBasicBlock *PredBB : Succ->predecessors()) {
if (PredBB == Edge.NewBB)
continue;
// If we are in this situation:
// FromBB1 FromBB2
// + +
// + + + +
// + + + +
// ... Split1 Split2 ...
// + +
// + +
// +
// Succ
// Instead of checking the domiance property with Split2, we
// check it with FromBB2 since Split2 is still unknown of the
// underlying DT structure.
if (NewBBs.count(PredBB)) {
assert(PredBB->pred_size() == 1 && "A basic block resulting from a "
"critical edge split has more "
"than one predecessor!");
PredBB = *PredBB->pred_begin();
}
if (!DT->dominates(SucccDTNode, DT->getNode(PredBB))) {
IsNewIDom[Idx] = false;
break;
}
}
++Idx;
}
// Now, update DT with the collected dominance properties info.
Idx = 0;
for (CriticalEdge &Edge : CriticalEdgesToSplit) {
// We know FromBB dominates NewBB.
MachineDomTreeNode *NewDTNode = DT->addNewBlock(Edge.NewBB, Edge.FromBB);
MachineDomTreeNode *SucccDTNode = DT->getNode(Edge.ToBB);
// If all the other predecessors of "Succ" are dominated by "Succ" itself
// then the new block is the new immediate dominator of "Succ". Otherwise,
// the new block doesn't dominate anything.
if (IsNewIDom[Idx])
DT->changeImmediateDominator(SucccDTNode, NewDTNode);
++Idx;
}
NewBBs.clear();
CriticalEdgesToSplit.clear();
}
public:
static char ID; // Pass ID, replacement for typeid
DominatorTreeBase<MachineBasicBlock>* DT;
MachineDominatorTree();
~MachineDominatorTree();
DominatorTreeBase<MachineBasicBlock> &getBase() {
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 std::vector<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 print(raw_ostream &OS, const Module*) const override;
/// \brief 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(CriticalEdge(FromBB, ToBB, NewBB));
}
};
//===-------------------------------------
/// DominatorTree GraphTraits specialization so the DominatorTree can be
/// iterable by generic graph iterators.
///
template<class T> struct GraphTraits;
template <> struct GraphTraits<MachineDomTreeNode *> {
typedef MachineDomTreeNode 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();
}
};
template <> struct GraphTraits<MachineDominatorTree*>
: public GraphTraits<MachineDomTreeNode *> {
static NodeType *getEntryNode(MachineDominatorTree *DT) {
return DT->getRootNode();
}
};
}
#endif