-//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator --------*- C++ -*--=//
+//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- 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 LoopInfo class that is used to identify natural loops
-// and determine the loop depth of various nodes of the CFG. Note that the
-// loops identified may actually be several natural loops that share the same
-// header node... not just a single natural loop.
+// and determine the loop depth of various nodes of the CFG. A natural loop
+// has exactly one entry-point, which is called the header. Note that natural
+// loops may actually be several loops that share the same header node.
+//
+// This analysis calculates the nesting structure of loops in a function. For
+// each natural loop identified, this analysis identifies natural loops
+// contained entirely within the loop and the basic blocks the make up the loop.
+//
+// It can calculate on the fly various bits of information, for example:
+//
+// * whether there is a preheader for the loop
+// * the number of back edges to the header
+// * whether or not a particular block branches out of the loop
+// * the successor blocks of the loop
+// * the loop depth
+// * etc...
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_LOOP_INFO_H
#define LLVM_ANALYSIS_LOOP_INFO_H
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/Dominators.h"
#include "llvm/Pass.h"
-#include <set>
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <map>
+
+namespace llvm {
-class DominatorSet;
+template<typename T>
+inline void RemoveFromVector(std::vector<T*> &V, T *N) {
+ typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N);
+ assert(I != V.end() && "N is not in this list!");
+ V.erase(I);
+}
+
+class DominatorTree;
class LoopInfo;
+class Loop;
+class PHINode;
+template<class N, class M> class LoopInfoBase;
+template<class N, class M> class LoopBase;
//===----------------------------------------------------------------------===//
-// Loop class - Instances of this class are used to represent loops that are
-// detected in the flow graph
-//
-class Loop {
- Loop *ParentLoop;
- std::vector<BasicBlock *> Blocks; // First entry is the header node
- std::vector<Loop*> SubLoops; // Loops contained entirely within this one
- unsigned LoopDepth; // Nesting depth of this loop
-
- Loop(const Loop &); // DO NOT IMPLEMENT
- const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
+/// LoopBase class - Instances of this class are used to represent loops that
+/// are detected in the flow graph
+///
+template<class BlockT, class LoopT>
+class LoopBase {
+ LoopT *ParentLoop;
+ // SubLoops - Loops contained entirely within this one.
+ std::vector<LoopT *> SubLoops;
+
+ // Blocks - The list of blocks in this loop. First entry is the header node.
+ std::vector<BlockT*> Blocks;
+
+ LoopBase(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION;
+ const LoopBase<BlockT, LoopT>&
+ operator=(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION;
public:
+ /// Loop ctor - This creates an empty loop.
+ LoopBase() : ParentLoop(0) {}
+ ~LoopBase() {
+ for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
+ delete SubLoops[i];
+ }
- inline unsigned getLoopDepth() const { return LoopDepth; }
- inline BasicBlock *getHeader() const { return Blocks.front(); }
+ /// getLoopDepth - Return the nesting level of this loop. An outer-most
+ /// loop has depth 1, for consistency with loop depth values used for basic
+ /// blocks, where depth 0 is used for blocks not inside any loops.
+ unsigned getLoopDepth() const {
+ unsigned D = 1;
+ for (const LoopT *CurLoop = ParentLoop; CurLoop;
+ CurLoop = CurLoop->ParentLoop)
+ ++D;
+ return D;
+ }
+ BlockT *getHeader() const { return Blocks.front(); }
+ LoopT *getParentLoop() const { return ParentLoop; }
- // contains - Return true of the specified basic block is in this loop
- bool contains(const BasicBlock *BB) const;
+ /// setParentLoop is a raw interface for bypassing addChildLoop.
+ void setParentLoop(LoopT *L) { ParentLoop = L; }
- // getSubLoops - Return the loops contained entirely within this loop
- inline const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
- inline const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
+ /// contains - Return true if the specified loop is contained within in
+ /// this loop.
+ ///
+ bool contains(const LoopT *L) const {
+ if (L == this) return true;
+ if (L == 0) return false;
+ return contains(L->getParentLoop());
+ }
- void print(std::ostream &O) const;
-private:
- friend class LoopInfo;
- inline Loop(BasicBlock *BB) { Blocks.push_back(BB); LoopDepth = 0; }
- ~Loop() {
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- delete SubLoops[i];
+ /// contains - Return true if the specified basic block is in this loop.
+ ///
+ bool contains(const BlockT *BB) const {
+ return std::find(block_begin(), block_end(), BB) != block_end();
+ }
+
+ /// contains - Return true if the specified instruction is in this loop.
+ ///
+ template<class InstT>
+ bool contains(const InstT *Inst) const {
+ return contains(Inst->getParent());
+ }
+
+ /// iterator/begin/end - Return the loops contained entirely within this loop.
+ ///
+ const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
+ std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; }
+ typedef typename std::vector<LoopT *>::const_iterator iterator;
+ typedef typename std::vector<LoopT *>::const_reverse_iterator
+ reverse_iterator;
+ iterator begin() const { return SubLoops.begin(); }
+ iterator end() const { return SubLoops.end(); }
+ reverse_iterator rbegin() const { return SubLoops.rbegin(); }
+ reverse_iterator rend() const { return SubLoops.rend(); }
+ bool empty() const { return SubLoops.empty(); }
+
+ /// getBlocks - Get a list of the basic blocks which make up this loop.
+ ///
+ const std::vector<BlockT*> &getBlocks() const { return Blocks; }
+ std::vector<BlockT*> &getBlocksVector() { return Blocks; }
+ typedef typename std::vector<BlockT*>::const_iterator block_iterator;
+ block_iterator block_begin() const { return Blocks.begin(); }
+ block_iterator block_end() const { return Blocks.end(); }
+
+ /// getNumBlocks - Get the number of blocks in this loop in constant time.
+ unsigned getNumBlocks() const {
+ return Blocks.size();
+ }
+
+ /// isLoopExiting - True if terminator in the block can branch to another
+ /// block that is outside of the current loop.
+ ///
+ bool isLoopExiting(const BlockT *BB) const {
+ typedef GraphTraits<BlockT*> BlockTraits;
+ for (typename BlockTraits::ChildIteratorType SI =
+ BlockTraits::child_begin(const_cast<BlockT*>(BB)),
+ SE = BlockTraits::child_end(const_cast<BlockT*>(BB)); SI != SE; ++SI) {
+ if (!contains(*SI))
+ return true;
+ }
+ return false;
+ }
+
+ /// getNumBackEdges - Calculate the number of back edges to the loop header
+ ///
+ unsigned getNumBackEdges() const {
+ unsigned NumBackEdges = 0;
+ BlockT *H = getHeader();
+
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType I =
+ InvBlockTraits::child_begin(const_cast<BlockT*>(H)),
+ E = InvBlockTraits::child_end(const_cast<BlockT*>(H)); I != E; ++I)
+ if (contains(*I))
+ ++NumBackEdges;
+
+ return NumBackEdges;
+ }
+
+ //===--------------------------------------------------------------------===//
+ // APIs for simple analysis of the loop.
+ //
+ // Note that all of these methods can fail on general loops (ie, there may not
+ // be a preheader, etc). For best success, the loop simplification and
+ // induction variable canonicalization pass should be used to normalize loops
+ // for easy analysis. These methods assume canonical loops.
+
+ /// getExitingBlocks - Return all blocks inside the loop that have successors
+ /// outside of the loop. These are the blocks _inside of the current loop_
+ /// which branch out. The returned list is always unique.
+ ///
+ void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
+
+ /// getExitingBlock - If getExitingBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ BlockT *getExitingBlock() const;
+
+ /// getExitBlocks - Return all of the successor blocks of this loop. These
+ /// are the blocks _outside of the current loop_ which are branched to.
+ ///
+ void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
+
+ /// getExitBlock - If getExitBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ BlockT *getExitBlock() const;
+
+ /// Edge type.
+ typedef std::pair<const BlockT*, const BlockT*> Edge;
+
+ /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
+ void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
+
+ /// getLoopPreheader - If there is a preheader for this loop, return it. A
+ /// loop has a preheader if there is only one edge to the header of the loop
+ /// from outside of the loop. If this is the case, the block branching to the
+ /// header of the loop is the preheader node.
+ ///
+ /// This method returns null if there is no preheader for the loop.
+ ///
+ BlockT *getLoopPreheader() const;
+
+ /// getLoopPredecessor - If the given loop's header has exactly one unique
+ /// predecessor outside the loop, return it. Otherwise return null.
+ /// This is less strict that the loop "preheader" concept, which requires
+ /// the predecessor to have exactly one successor.
+ ///
+ BlockT *getLoopPredecessor() const;
+
+ /// getLoopLatch - If there is a single latch block for this loop, return it.
+ /// A latch block is a block that contains a branch back to the header.
+ BlockT *getLoopLatch() const;
+
+ //===--------------------------------------------------------------------===//
+ // APIs for updating loop information after changing the CFG
+ //
+
+ /// addBasicBlockToLoop - This method is used by other analyses to update loop
+ /// information. NewBB is set to be a new member of the current loop.
+ /// Because of this, it is added as a member of all parent loops, and is added
+ /// to the specified LoopInfo object as being in the current basic block. It
+ /// is not valid to replace the loop header with this method.
+ ///
+ void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
+
+ /// replaceChildLoopWith - This is used when splitting loops up. It replaces
+ /// the OldChild entry in our children list with NewChild, and updates the
+ /// parent pointer of OldChild to be null and the NewChild to be this loop.
+ /// This updates the loop depth of the new child.
+ void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
+
+ /// addChildLoop - Add the specified loop to be a child of this loop. This
+ /// updates the loop depth of the new child.
+ ///
+ void addChildLoop(LoopT *NewChild) {
+ assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ NewChild->ParentLoop = static_cast<LoopT *>(this);
+ SubLoops.push_back(NewChild);
}
-
- void setLoopDepth(unsigned Level) {
- LoopDepth = Level;
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- SubLoops[i]->setLoopDepth(Level+1);
+
+ /// removeChildLoop - This removes the specified child from being a subloop of
+ /// this loop. The loop is not deleted, as it will presumably be inserted
+ /// into another loop.
+ LoopT *removeChildLoop(iterator I) {
+ assert(I != SubLoops.end() && "Cannot remove end iterator!");
+ LoopT *Child = *I;
+ assert(Child->ParentLoop == this && "Child is not a child of this loop!");
+ SubLoops.erase(SubLoops.begin()+(I-begin()));
+ Child->ParentLoop = 0;
+ return Child;
+ }
+
+ /// addBlockEntry - This adds a basic block directly to the basic block list.
+ /// This should only be used by transformations that create new loops. Other
+ /// transformations should use addBasicBlockToLoop.
+ void addBlockEntry(BlockT *BB) {
+ Blocks.push_back(BB);
+ }
+
+ /// moveToHeader - This method is used to move BB (which must be part of this
+ /// loop) to be the loop header of the loop (the block that dominates all
+ /// others).
+ void moveToHeader(BlockT *BB) {
+ if (Blocks[0] == BB) return;
+ for (unsigned i = 0; ; ++i) {
+ assert(i != Blocks.size() && "Loop does not contain BB!");
+ if (Blocks[i] == BB) {
+ Blocks[i] = Blocks[0];
+ Blocks[0] = BB;
+ return;
+ }
+ }
+ }
+
+ /// removeBlockFromLoop - This removes the specified basic block from the
+ /// current loop, updating the Blocks as appropriate. This does not update
+ /// the mapping in the LoopInfo class.
+ void removeBlockFromLoop(BlockT *BB) {
+ RemoveFromVector(Blocks, BB);
+ }
+
+ /// verifyLoop - Verify loop structure
+ void verifyLoop() const;
+
+ /// verifyLoop - Verify loop structure of this loop and all nested loops.
+ void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
+
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+protected:
+ friend class LoopInfoBase<BlockT, LoopT>;
+ explicit LoopBase(BlockT *BB) : ParentLoop(0) {
+ Blocks.push_back(BB);
}
};
+template<class BlockT, class LoopT>
+raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
+ Loop.print(OS);
+ return OS;
+}
+
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template class LoopBase<BasicBlock, Loop>;
+#endif
+
+class Loop : public LoopBase<BasicBlock, Loop> {
+public:
+ Loop() {}
+
+ /// isLoopInvariant - Return true if the specified value is loop invariant
+ ///
+ bool isLoopInvariant(Value *V) const;
+
+ /// hasLoopInvariantOperands - Return true if all the operands of the
+ /// specified instruction are loop invariant.
+ bool hasLoopInvariantOperands(Instruction *I) const;
+
+ /// makeLoopInvariant - If the given value is an instruction inside of the
+ /// loop and it can be hoisted, do so to make it trivially loop-invariant.
+ /// Return true if the value after any hoisting is loop invariant. This
+ /// function can be used as a slightly more aggressive replacement for
+ /// isLoopInvariant.
+ ///
+ /// If InsertPt is specified, it is the point to hoist instructions to.
+ /// If null, the terminator of the loop preheader is used.
+ ///
+ bool makeLoopInvariant(Value *V, bool &Changed,
+ Instruction *InsertPt = 0) const;
+
+ /// makeLoopInvariant - If the given instruction is inside of the
+ /// loop and it can be hoisted, do so to make it trivially loop-invariant.
+ /// Return true if the instruction after any hoisting is loop invariant. This
+ /// function can be used as a slightly more aggressive replacement for
+ /// isLoopInvariant.
+ ///
+ /// If InsertPt is specified, it is the point to hoist instructions to.
+ /// If null, the terminator of the loop preheader is used.
+ ///
+ bool makeLoopInvariant(Instruction *I, bool &Changed,
+ Instruction *InsertPt = 0) const;
+
+ /// getCanonicalInductionVariable - Check to see if the loop has a canonical
+ /// induction variable: an integer recurrence that starts at 0 and increments
+ /// by one each time through the loop. If so, return the phi node that
+ /// corresponds to it.
+ ///
+ /// The IndVarSimplify pass transforms loops to have a canonical induction
+ /// variable.
+ ///
+ PHINode *getCanonicalInductionVariable() const;
+
+ /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ bool isLCSSAForm(DominatorTree &DT) const;
+
+ /// isLoopSimplifyForm - Return true if the Loop is in the form that
+ /// the LoopSimplify form transforms loops to, which is sometimes called
+ /// normal form.
+ bool isLoopSimplifyForm() const;
+
+ /// isSafeToClone - Return true if the loop body is safe to clone in practice.
+ bool isSafeToClone() const;
+
+ /// hasDedicatedExits - Return true if no exit block for the loop
+ /// has a predecessor that is outside the loop.
+ bool hasDedicatedExits() const;
+
+ /// getUniqueExitBlocks - Return all unique successor blocks of this loop.
+ /// These are the blocks _outside of the current loop_ which are branched to.
+ /// This assumes that loop exits are in canonical form.
+ ///
+ void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
+
+ /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
+ /// block, return that block. Otherwise return null.
+ BasicBlock *getUniqueExitBlock() const;
+
+ void dump() const;
+private:
+ friend class LoopInfoBase<BasicBlock, Loop>;
+ explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
+};
//===----------------------------------------------------------------------===//
-// LoopInfo - This class builds and contains all of the top level loop
-// structures in the specified function.
-//
-class LoopInfo : public FunctionPass {
+/// LoopInfo - This class builds and contains all of the top level loop
+/// structures in the specified function.
+///
+
+template<class BlockT, class LoopT>
+class LoopInfoBase {
// BBMap - Mapping of basic blocks to the inner most loop they occur in
- std::map<BasicBlock*, Loop*> BBMap;
- std::vector<Loop*> TopLevelLoops;
+ DenseMap<BlockT *, LoopT *> BBMap;
+ std::vector<LoopT *> TopLevelLoops;
+ friend class LoopBase<BlockT, LoopT>;
+ friend class LoopInfo;
+
+ void operator=(const LoopInfoBase &) LLVM_DELETED_FUNCTION;
+ LoopInfoBase(const LoopInfo &) LLVM_DELETED_FUNCTION;
public:
- static AnalysisID ID; // LoopInfo Analysis ID
+ LoopInfoBase() { }
+ ~LoopInfoBase() { releaseMemory(); }
- // LoopInfo ctor - Calculate the natural loop information for a CFG
- ~LoopInfo() { releaseMemory(); }
+ void releaseMemory() {
+ for (typename std::vector<LoopT *>::iterator I =
+ TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
+ delete *I; // Delete all of the loops...
- const std::vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; }
+ BBMap.clear(); // Reset internal state of analysis
+ TopLevelLoops.clear();
+ }
- // getLoopFor - Return the inner most loop that BB lives in. If a basic block
- // is in no loop (for example the entry node), null is returned.
- //
- const Loop *getLoopFor(const BasicBlock *BB) const {
- std::map<BasicBlock *, Loop*>::const_iterator I=BBMap.find((BasicBlock*)BB);
- return I != BBMap.end() ? I->second : 0;
+ /// iterator/begin/end - The interface to the top-level loops in the current
+ /// function.
+ ///
+ typedef typename std::vector<LoopT *>::const_iterator iterator;
+ typedef typename std::vector<LoopT *>::const_reverse_iterator
+ reverse_iterator;
+ iterator begin() const { return TopLevelLoops.begin(); }
+ iterator end() const { return TopLevelLoops.end(); }
+ reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
+ reverse_iterator rend() const { return TopLevelLoops.rend(); }
+ bool empty() const { return TopLevelLoops.empty(); }
+
+ /// getLoopFor - Return the inner most loop that BB lives in. If a basic
+ /// block is in no loop (for example the entry node), null is returned.
+ ///
+ LoopT *getLoopFor(const BlockT *BB) const {
+ return BBMap.lookup(const_cast<BlockT*>(BB));
}
- inline const Loop *operator[](const BasicBlock *BB) const {
+
+ /// operator[] - same as getLoopFor...
+ ///
+ const LoopT *operator[](const BlockT *BB) const {
return getLoopFor(BB);
}
- // getLoopDepth - Return the loop nesting level of the specified block...
- unsigned getLoopDepth(const BasicBlock *BB) const {
- const Loop *L = getLoopFor(BB);
+ /// getLoopDepth - Return the loop nesting level of the specified block. A
+ /// depth of 0 means the block is not inside any loop.
+ ///
+ unsigned getLoopDepth(const BlockT *BB) const {
+ const LoopT *L = getLoopFor(BB);
return L ? L->getLoopDepth() : 0;
}
-#if 0
// isLoopHeader - True if the block is a loop header node
- bool isLoopHeader(BasicBlock *BB) const {
- return getLoopFor(BB)->getHeader() == BB;
+ bool isLoopHeader(BlockT *BB) const {
+ const LoopT *L = getLoopFor(BB);
+ return L && L->getHeader() == BB;
+ }
+
+ /// removeLoop - This removes the specified top-level loop from this loop info
+ /// object. The loop is not deleted, as it will presumably be inserted into
+ /// another loop.
+ LoopT *removeLoop(iterator I) {
+ assert(I != end() && "Cannot remove end iterator!");
+ LoopT *L = *I;
+ assert(L->getParentLoop() == 0 && "Not a top-level loop!");
+ TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
+ return L;
+ }
+
+ /// changeLoopFor - Change the top-level loop that contains BB to the
+ /// specified loop. This should be used by transformations that restructure
+ /// the loop hierarchy tree.
+ void changeLoopFor(BlockT *BB, LoopT *L) {
+ if (!L) {
+ BBMap.erase(BB);
+ return;
+ }
+ BBMap[BB] = L;
+ }
+
+ /// changeTopLevelLoop - Replace the specified loop in the top-level loops
+ /// list with the indicated loop.
+ void changeTopLevelLoop(LoopT *OldLoop,
+ LoopT *NewLoop) {
+ typename std::vector<LoopT *>::iterator I =
+ std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
+ assert(I != TopLevelLoops.end() && "Old loop not at top level!");
+ *I = NewLoop;
+ assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 &&
+ "Loops already embedded into a subloop!");
+ }
+
+ /// addTopLevelLoop - This adds the specified loop to the collection of
+ /// top-level loops.
+ void addTopLevelLoop(LoopT *New) {
+ assert(New->getParentLoop() == 0 && "Loop already in subloop!");
+ TopLevelLoops.push_back(New);
+ }
+
+ /// removeBlock - This method completely removes BB from all data structures,
+ /// including all of the Loop objects it is nested in and our mapping from
+ /// BasicBlocks to loops.
+ void removeBlock(BlockT *BB) {
+ typename DenseMap<BlockT *, LoopT *>::iterator I = BBMap.find(BB);
+ if (I != BBMap.end()) {
+ for (LoopT *L = I->second; L; L = L->getParentLoop())
+ L->removeBlockFromLoop(BB);
+
+ BBMap.erase(I);
+ }
+ }
+
+ // Internals
+
+ static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
+ const LoopT *ParentLoop) {
+ if (SubLoop == 0) return true;
+ if (SubLoop == ParentLoop) return false;
+ return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
}
- // isLoopEnd - True if block jumps to loop entry
- bool isLoopEnd(BasicBlock *BB) const;
- // isLoopExit - True if block is the loop exit
- bool isLoopExit(BasicBlock *BB) const;
+
+ /// Create the loop forest using a stable algorithm.
+ void Analyze(DominatorTreeBase<BlockT> &DomTree);
+
+ // Debugging
+
+ void print(raw_ostream &OS) const;
+};
+
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
#endif
- // runOnFunction - Pass framework implementation
+class LoopInfo : public FunctionPass {
+ LoopInfoBase<BasicBlock, Loop> LI;
+ friend class LoopBase<BasicBlock, Loop>;
+
+ void operator=(const LoopInfo &) LLVM_DELETED_FUNCTION;
+ LoopInfo(const LoopInfo &) LLVM_DELETED_FUNCTION;
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopInfo() : FunctionPass(ID) {
+ initializeLoopInfoPass(*PassRegistry::getPassRegistry());
+ }
+
+ LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
+
+ /// iterator/begin/end - The interface to the top-level loops in the current
+ /// function.
+ ///
+ typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator;
+ typedef LoopInfoBase<BasicBlock, Loop>::reverse_iterator reverse_iterator;
+ inline iterator begin() const { return LI.begin(); }
+ inline iterator end() const { return LI.end(); }
+ inline reverse_iterator rbegin() const { return LI.rbegin(); }
+ inline reverse_iterator rend() const { return LI.rend(); }
+ bool empty() const { return LI.empty(); }
+
+ /// getLoopFor - Return the inner most loop that BB lives in. If a basic
+ /// block is in no loop (for example the entry node), null is returned.
+ ///
+ inline Loop *getLoopFor(const BasicBlock *BB) const {
+ return LI.getLoopFor(BB);
+ }
+
+ /// operator[] - same as getLoopFor...
+ ///
+ inline const Loop *operator[](const BasicBlock *BB) const {
+ return LI.getLoopFor(BB);
+ }
+
+ /// getLoopDepth - Return the loop nesting level of the specified block. A
+ /// depth of 0 means the block is not inside any loop.
+ ///
+ inline unsigned getLoopDepth(const BasicBlock *BB) const {
+ return LI.getLoopDepth(BB);
+ }
+
+ // isLoopHeader - True if the block is a loop header node
+ inline bool isLoopHeader(BasicBlock *BB) const {
+ return LI.isLoopHeader(BB);
+ }
+
+ /// runOnFunction - Calculate the natural loop information.
+ ///
virtual bool runOnFunction(Function &F);
- virtual void releaseMemory();
- void print(std::ostream &O) const;
+ virtual void verifyAnalysis() const;
+
+ virtual void releaseMemory() { LI.releaseMemory(); }
+
+ virtual void print(raw_ostream &O, const Module* M = 0) const;
- // getAnalysisUsage - Provide loop info, require dominator set
- //
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
-private:
- void Calculate(const DominatorSet &DS);
- Loop *ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS);
+ /// removeLoop - This removes the specified top-level loop from this loop info
+ /// object. The loop is not deleted, as it will presumably be inserted into
+ /// another loop.
+ inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); }
+
+ /// changeLoopFor - Change the top-level loop that contains BB to the
+ /// specified loop. This should be used by transformations that restructure
+ /// the loop hierarchy tree.
+ inline void changeLoopFor(BasicBlock *BB, Loop *L) {
+ LI.changeLoopFor(BB, L);
+ }
+
+ /// changeTopLevelLoop - Replace the specified loop in the top-level loops
+ /// list with the indicated loop.
+ inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
+ LI.changeTopLevelLoop(OldLoop, NewLoop);
+ }
+
+ /// addTopLevelLoop - This adds the specified loop to the collection of
+ /// top-level loops.
+ inline void addTopLevelLoop(Loop *New) {
+ LI.addTopLevelLoop(New);
+ }
+
+ /// removeBlock - This method completely removes BB from all data structures,
+ /// including all of the Loop objects it is nested in and our mapping from
+ /// BasicBlocks to loops.
+ void removeBlock(BasicBlock *BB) {
+ LI.removeBlock(BB);
+ }
+
+ /// updateUnloop - Update LoopInfo after removing the last backedge from a
+ /// loop--now the "unloop". This updates the loop forest and parent loops for
+ /// each block so that Unloop is no longer referenced, but the caller must
+ /// actually delete the Unloop object.
+ void updateUnloop(Loop *Unloop);
+
+ /// replacementPreservesLCSSAForm - Returns true if replacing From with To
+ /// everywhere is guaranteed to preserve LCSSA form.
+ bool replacementPreservesLCSSAForm(Instruction *From, Value *To) {
+ // Preserving LCSSA form is only problematic if the replacing value is an
+ // instruction.
+ Instruction *I = dyn_cast<Instruction>(To);
+ if (!I) return true;
+ // If both instructions are defined in the same basic block then replacement
+ // cannot break LCSSA form.
+ if (I->getParent() == From->getParent())
+ return true;
+ // If the instruction is not defined in a loop then it can safely replace
+ // anything.
+ Loop *ToLoop = getLoopFor(I->getParent());
+ if (!ToLoop) return true;
+ // If the replacing instruction is defined in the same loop as the original
+ // instruction, or in a loop that contains it as an inner loop, then using
+ // it as a replacement will not break LCSSA form.
+ return ToLoop->contains(getLoopFor(From->getParent()));
+ }
};
+
+// Allow clients to walk the list of nested loops...
+template <> struct GraphTraits<const Loop*> {
+ typedef const Loop NodeType;
+ typedef LoopInfo::iterator ChildIteratorType;
+
+ static NodeType *getEntryNode(const Loop *L) { return L; }
+ static inline ChildIteratorType child_begin(NodeType *N) {
+ return N->begin();
+ }
+ static inline ChildIteratorType child_end(NodeType *N) {
+ return N->end();
+ }
+};
+
+template <> struct GraphTraits<Loop*> {
+ typedef Loop NodeType;
+ typedef LoopInfo::iterator ChildIteratorType;
+
+ static NodeType *getEntryNode(Loop *L) { return L; }
+ static inline ChildIteratorType child_begin(NodeType *N) {
+ return N->begin();
+ }
+ static inline ChildIteratorType child_end(NodeType *N) {
+ return N->end();
+ }
+};
+
+} // End llvm namespace
+
#endif
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