-//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator --------*- C++ -*--=//
+//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and 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 natural
-// loops may actually be several loops that share the same header node...
+// 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 function, the basic blocks the make up the
-// loop, the nesting depth of the loop, and the successor blocks of the loop.
+// contained entirely within the loop and the basic blocks the make up the loop.
//
-// It can calculate on the fly a variety of different bits of information, such
-// as whether there is a preheader for the loop, the number of back edges to the
-// header, and whether or not a particular block branches out of 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
+// * the trip count
+// * etc...
//
//===----------------------------------------------------------------------===//
#define LLVM_ANALYSIS_LOOP_INFO_H
#include "llvm/Pass.h"
-#include <set>
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Streams.h"
+#include <algorithm>
+#include <ostream>
+
+template<typename T>
+static 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);
+}
+
+namespace llvm {
-class DominatorSet;
+class DominatorTree;
class LoopInfo;
+class PHINode;
+class Instruction;
+template<class N> class LoopInfoBase;
//===----------------------------------------------------------------------===//
-/// Loop class - Instances of this class are used to represent loops that are
-/// detected in the flow graph
+/// LoopBase class - Instances of this class are used to represent loops that are
+/// detected in the flow graph
///
-class Loop {
- Loop *ParentLoop;
- std::vector<Loop*> SubLoops; // Loops contained entirely within this one
- std::vector<BasicBlock *> Blocks; // First entry is the header node
- std::vector<BasicBlock *> ExitBlocks; // Reachable blocks outside the loop
- unsigned LoopDepth; // Nesting depth of this loop
-
- Loop(const Loop &); // DO NOT IMPLEMENT
- const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
+template<class BlockT>
+class LoopBase {
+ LoopBase<BlockT> *ParentLoop;
+ std::vector<LoopBase<BlockT>*> SubLoops; // Loops contained entirely within this one
+ std::vector<BlockT*> Blocks; // First entry is the header node
+
+ LoopBase(const LoopBase<BlockT> &); // DO NOT IMPLEMENT
+ const LoopBase<BlockT> &operator=(const LoopBase<BlockT> &); // DO NOT IMPLEMENT
public:
+ /// Loop ctor - This creates an empty loop.
+ LoopBase() : ParentLoop(0) {}
+ ~LoopBase() {
+ for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
+ delete SubLoops[i];
+ }
- inline unsigned getLoopDepth() const { return LoopDepth; }
- inline BasicBlock *getHeader() const { return Blocks.front(); }
- inline Loop *getParentLoop() const { return ParentLoop; }
+ unsigned getLoopDepth() const {
+ unsigned D = 0;
+ for (const LoopBase<BlockT> *CurLoop = this; CurLoop;
+ CurLoop = CurLoop->ParentLoop)
+ ++D;
+ return D;
+ }
+ BlockT *getHeader() const { return Blocks.front(); }
+ LoopBase<BlockT> *getParentLoop() const { return ParentLoop; }
/// contains - Return true of the specified basic block is in this loop
- bool contains(const BasicBlock *BB) const;
+ ///
+ bool contains(const BlockT *BB) const {
+ return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end();
+ }
- /// getSubLoops - Return the loops contained entirely within this loop
+ /// iterator/begin/end - Return the loops contained entirely within this loop.
///
- const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
+ const std::vector<LoopBase<BlockT>*> &getSubLoops() const { return SubLoops; }
+ typedef typename std::vector<LoopBase<BlockT>*>::const_iterator iterator;
+ iterator begin() const { return SubLoops.begin(); }
+ iterator end() const { return SubLoops.end(); }
+ bool empty() const { return SubLoops.empty(); }
/// getBlocks - Get a list of the basic blocks which make up this loop.
///
- const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
+ const std::vector<BlockT*> &getBlocks() const { 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(); }
+
+ /// isLoopExit - True if terminator in the block can branch to another block
+ /// that is outside of the current loop.
+ ///
+ bool isLoopExit(const BlockT *BB) const {
+ for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(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();
+
+ for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I)
+ if (contains(*I))
+ ++NumBackEdges;
+
+ return NumBackEdges;
+ }
+
+ /// isLoopInvariant - Return true if the specified value is loop invariant
+ ///
+ bool isLoopInvariant(Value *V) const {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ return !contains(I->getParent());
+ return true; // All non-instructions are loop invariant
+ }
+
+ //===--------------------------------------------------------------------===//
+ // 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 {
+ // Sort the blocks vector so that we can use binary search to do quick
+ // lookups.
+ SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
+ std::sort(LoopBBs.begin(), LoopBBs.end());
+
+ for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
+ BE = Blocks.end(); BI != BE; ++BI)
+ for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
+ if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) {
+ // Not in current loop? It must be an exit block.
+ ExitingBlocks.push_back(*BI);
+ break;
+ }
+ }
/// getExitBlocks - Return all of the successor blocks of this loop. These
/// are the blocks _outside of the current loop_ which are branched to.
///
- const std::vector<BasicBlock*> &getExitBlocks() const { return ExitBlocks; }
+ void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
+ // Sort the blocks vector so that we can use binary search to do quick
+ // lookups.
+ SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
+ std::sort(LoopBBs.begin(), LoopBBs.end());
- /// isLoopExit - True if terminator in the block can branch to another block
- /// that is outside of the current loop. The reached block should be in the
- /// ExitBlocks list.
- ///
- bool isLoopExit(const BasicBlock *BB) const;
+ for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
+ BE = Blocks.end(); BI != BE; ++BI)
+ for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
+ if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
+ // Not in current loop? It must be an exit block.
+ ExitBlocks.push_back(*I);
+ }
- /// getNumBackEdges - Calculate the number of back edges to the loop header
+ /// 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 is in canonical form.
///
- unsigned getNumBackEdges() const;
+ void getUniqueExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const {
+ // Sort the blocks vector so that we can use binary search to do quick
+ // lookups.
+ SmallVector<BlockT*, 128> LoopBBs(block_begin(), block_end());
+ std::sort(LoopBBs.begin(), LoopBBs.end());
+
+ std::vector<BlockT*> switchExitBlocks;
+
+ for (typename std::vector<BlockT*>::const_iterator BI = Blocks.begin(),
+ BE = Blocks.end(); BI != BE; ++BI) {
+
+ BlockT *current = *BI;
+ switchExitBlocks.clear();
+
+ for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
+ if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
+ // If block is inside the loop then it is not a exit block.
+ continue;
+
+ pred_iterator PI = pred_begin(*I);
+ BlockT *firstPred = *PI;
+
+ // If current basic block is this exit block's first predecessor
+ // then only insert exit block in to the output ExitBlocks vector.
+ // This ensures that same exit block is not inserted twice into
+ // ExitBlocks vector.
+ if (current != firstPred)
+ continue;
+
+ // If a terminator has more then two successors, for example SwitchInst,
+ // then it is possible that there are multiple edges from current block
+ // to one exit block.
+ if (current->getTerminator()->getNumSuccessors() <= 2) {
+ ExitBlocks.push_back(*I);
+ continue;
+ }
+
+ // In case of multiple edges from current block to exit block, collect
+ // only one edge in ExitBlocks. Use switchExitBlocks to keep track of
+ // duplicate edges.
+ if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I)
+ == switchExitBlocks.end()) {
+ switchExitBlocks.push_back(*I);
+ ExitBlocks.push_back(*I);
+ }
+ }
+ }
+ }
/// 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. The "preheaders" pass can be
- /// "Required" to ensure that there is always a preheader node for every loop.
+ /// header of the loop is the preheader node.
+ ///
+ /// This method returns null if there is no preheader for the loop.
+ ///
+ BlockT *getLoopPreheader() const {
+ // Keep track of nodes outside the loop branching to the header...
+ BlockT *Out = 0;
+
+ // Loop over the predecessors of the header node...
+ BlockT *Header = getHeader();
+ for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+ PI != PE; ++PI)
+ if (!contains(*PI)) { // If the block is not in the loop...
+ if (Out && Out != *PI)
+ return 0; // Multiple predecessors outside the loop
+ Out = *PI;
+ }
+
+ // Make sure there is only one exit out of the preheader.
+ assert(Out && "Header of loop has no predecessors from outside loop?");
+ succ_iterator SI = succ_begin(Out);
+ ++SI;
+ if (SI != succ_end(Out))
+ return 0; // Multiple exits from the block, must not be a preheader.
+
+ // If there is exactly one preheader, return it. If there was zero, then Out
+ // is still null.
+ return Out;
+ }
+
+ /// getLoopLatch - If there is a latch block for this loop, return it. A
+ /// latch block is the canonical backedge for a loop. A loop header in normal
+ /// form has two edges into it: one from a preheader and one from a latch
+ /// block.
+ BlockT *getLoopLatch() const {
+ BlockT *Header = getHeader();
+ pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+ if (PI == PE) return 0; // no preds?
+
+ BlockT *Latch = 0;
+ if (contains(*PI))
+ Latch = *PI;
+ ++PI;
+ if (PI == PE) return 0; // only one pred?
+
+ if (contains(*PI)) {
+ if (Latch) return 0; // multiple backedges
+ Latch = *PI;
+ }
+ ++PI;
+ if (PI != PE) return 0; // more than two preds
+
+ return Latch;
+ }
+
+ /// 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.
+ ///
+ PHINode *getCanonicalInductionVariable() const {
+ BlockT *H = getHeader();
+
+ BlockT *Incoming = 0, *Backedge = 0;
+ pred_iterator PI = pred_begin(H);
+ assert(PI != pred_end(H) && "Loop must have at least one backedge!");
+ Backedge = *PI++;
+ if (PI == pred_end(H)) return 0; // dead loop
+ Incoming = *PI++;
+ if (PI != pred_end(H)) return 0; // multiple backedges?
+
+ if (contains(Incoming)) {
+ if (contains(Backedge))
+ return 0;
+ std::swap(Incoming, Backedge);
+ } else if (!contains(Backedge))
+ return 0;
+
+ // Loop over all of the PHI nodes, looking for a canonical indvar.
+ for (typename BlockT::iterator I = H->begin(); isa<PHINode>(I); ++I) {
+ PHINode *PN = cast<PHINode>(I);
+ if (Instruction *Inc =
+ dyn_cast<Instruction>(PN->getIncomingValueForBlock(Backedge)))
+ if (Inc->getOpcode() == Instruction::Add && Inc->getOperand(0) == PN)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Inc->getOperand(1)))
+ if (CI->equalsInt(1))
+ return PN;
+ }
+ return 0;
+ }
+
+ /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds
+ /// the canonical induction variable value for the "next" iteration of the
+ /// loop. This always succeeds if getCanonicalInductionVariable succeeds.
///
- /// This method returns null if there is no preheader for the loop (either
- /// because the loop is dead or because multiple blocks branch to the header
- /// node of this loop).
+ Instruction *getCanonicalInductionVariableIncrement() const {
+ if (PHINode *PN = getCanonicalInductionVariable()) {
+ bool P1InLoop = contains(PN->getIncomingBlock(1));
+ return cast<Instruction>(PN->getIncomingValue(P1InLoop));
+ }
+ return 0;
+ }
+
+ /// getTripCount - Return a loop-invariant LLVM value indicating the number of
+ /// times the loop will be executed. Note that this means that the backedge
+ /// of the loop executes N-1 times. If the trip-count cannot be determined,
+ /// this returns null.
///
- BasicBlock *getLoopPreheader() const;
+ Value *getTripCount() const {
+ // Canonical loops will end with a 'cmp ne I, V', where I is the incremented
+ // canonical induction variable and V is the trip count of the loop.
+ Instruction *Inc = getCanonicalInductionVariableIncrement();
+ if (Inc == 0) return 0;
+ PHINode *IV = cast<PHINode>(Inc->getOperand(0));
+
+ BlockT *BackedgeBlock =
+ IV->getIncomingBlock(contains(IV->getIncomingBlock(1)));
+
+ if (BranchInst *BI = dyn_cast<BranchInst>(BackedgeBlock->getTerminator()))
+ if (BI->isConditional()) {
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
+ if (ICI->getOperand(0) == Inc)
+ if (BI->getSuccessor(0) == getHeader()) {
+ if (ICI->getPredicate() == ICmpInst::ICMP_NE)
+ return ICI->getOperand(1);
+ } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) {
+ return ICI->getOperand(1);
+ }
+ }
+ }
+
+ return 0;
+ }
+
+ /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ bool isLCSSAForm() const {
+ // Sort the blocks vector so that we can use binary search to do quick
+ // lookups.
+ SmallPtrSet<BlockT*, 16> LoopBBs(block_begin(), block_end());
+
+ for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
+ BlockT *BB = *BI;
+ for (typename BlockT::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
+ ++UI) {
+ BlockT *UserBB = cast<Instruction>(*UI)->getParent();
+ if (PHINode *P = dyn_cast<PHINode>(*UI)) {
+ unsigned OperandNo = UI.getOperandNo();
+ UserBB = P->getIncomingBlock(OperandNo/2);
+ }
+
+ // Check the current block, as a fast-path. Most values are used in the
+ // same block they are defined in.
+ if (UserBB != BB && !LoopBBs.count(UserBB))
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ //===--------------------------------------------------------------------===//
+ // 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.
/// 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(BasicBlock *NewBB, LoopInfo &LI);
+ void addBasicBlockToLoop(BlockT *NewBB, LoopInfo &LI);
- /// changeExitBlock - This method is used to update loop information. One
- /// instance of the specified Old basic block is removed from the exit list
- /// and replaced with New.
+ /// 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(LoopBase<BlockT> *OldChild,
+ LoopBase<BlockT> *NewChild) {
+ assert(OldChild->ParentLoop == this && "This loop is already broken!");
+ assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ typename std::vector<LoopBase<BlockT>*>::iterator I =
+ std::find(SubLoops.begin(), SubLoops.end(), OldChild);
+ assert(I != SubLoops.end() && "OldChild not in loop!");
+ *I = NewChild;
+ OldChild->ParentLoop = 0;
+ NewChild->ParentLoop = this;
+ }
+
+ /// addChildLoop - Add the specified loop to be a child of this loop. This
+ /// updates the loop depth of the new child.
///
- void changeExitBlock(BasicBlock *Old, BasicBlock *New);
+ void addChildLoop(LoopBase<BlockT> *NewChild) {
+ assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ NewChild->ParentLoop = this;
+ SubLoops.push_back(NewChild);
+ }
- void print(std::ostream &O) const;
-private:
- friend class LoopInfo;
- inline Loop(BasicBlock *BB) : ParentLoop(0) {
- Blocks.push_back(BB); LoopDepth = 0;
+ /// 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.
+ LoopBase<BlockT> *removeChildLoop(iterator I) {
+ assert(I != SubLoops.end() && "Cannot remove end iterator!");
+ LoopBase<BlockT> *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;
}
- ~Loop() {
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- delete SubLoops[i];
+
+ /// 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 {
+#ifndef NDEBUG
+ assert (getHeader() && "Loop header is missing");
+ assert (getLoopPreheader() && "Loop preheader is missing");
+ assert (getLoopLatch() && "Loop latch is missing");
+ for (typename std::vector<LoopBase<BlockT>*>::const_iterator I =
+ SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
+ (*I)->verifyLoop();
+#endif
+ }
+
+ void print(std::ostream &OS, unsigned Depth = 0) const {
+ OS << std::string(Depth*2, ' ') << "Loop Containing: ";
+
+ for (unsigned i = 0; i < getBlocks().size(); ++i) {
+ if (i) OS << ",";
+ WriteAsOperand(OS, getBlocks()[i], false);
+ }
+ OS << "\n";
+
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ (*I)->print(OS, Depth+2);
}
- void setLoopDepth(unsigned Level) {
- LoopDepth = Level;
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- SubLoops[i]->setLoopDepth(Level+1);
+ void print(std::ostream *O, unsigned Depth = 0) const {
+ if (O) print(*O, Depth);
+ }
+
+ void dump() const {
+ print(cerr);
+ }
+
+private:
+ friend class LoopInfoBase<BlockT>;
+ LoopBase(BlockT *BB) : ParentLoop(0) {
+ Blocks.push_back(BB);
}
};
+typedef LoopBase<BasicBlock> Loop;
//===----------------------------------------------------------------------===//
/// LoopInfo - This class builds and contains all of the top level loop
/// structures in the specified function.
///
-class LoopInfo : public FunctionPass {
+
+template<class BlockT>
+class LoopInfoBase {
// BBMap - Mapping of basic blocks to the inner most loop they occur in
- std::map<BasicBlock*, Loop*> BBMap;
- std::vector<Loop*> TopLevelLoops;
- friend class Loop;
+ std::map<BlockT*, Loop*> BBMap;
+ std::vector<LoopBase<BlockT>*> TopLevelLoops;
+ friend class LoopBase<BlockT>;
+
public:
- ~LoopInfo() { releaseMemory(); }
-
- const std::vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; }
+ LoopInfoBase() { }
+ ~LoopInfoBase() { releaseMemory(); }
+
+ void releaseMemory() {
+ for (typename std::vector<LoopBase<BlockT>* >::iterator I =
+ TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
+ delete *I; // Delete all of the loops...
+ BBMap.clear(); // Reset internal state of analysis
+ TopLevelLoops.clear();
+ }
+
+ /// iterator/begin/end - The interface to the top-level loops in the current
+ /// function.
+ ///
+ typedef typename std::vector<LoopBase<BlockT>*>::const_iterator iterator;
+ iterator begin() const { return TopLevelLoops.begin(); }
+ iterator end() const { return TopLevelLoops.end(); }
+
/// 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);
+ LoopBase<BlockT> *getLoopFor(const BlockT *BB) const {
+ typename std::map<BlockT *, LoopBase<BlockT>*>::const_iterator I=
+ BBMap.find(const_cast<BasicBlock*>(BB));
return I != BBMap.end() ? I->second : 0;
}
-
+
/// operator[] - same as getLoopFor...
///
- inline const Loop *operator[](const BasicBlock *BB) const {
+ const LoopBase<BlockT> *operator[](const BlockT *BB) const {
return getLoopFor(BB);
}
-
+
/// getLoopDepth - Return the loop nesting level of the specified block...
///
- unsigned getLoopDepth(const BasicBlock *BB) const {
+ unsigned getLoopDepth(const BlockT *BB) const {
const Loop *L = getLoopFor(BB);
return L ? L->getLoopDepth() : 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 Loop *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.
+ LoopBase<BlockT> *removeLoop(iterator I) {
+ assert(I != end() && "Cannot remove end iterator!");
+ LoopBase<BlockT> *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, LoopBase<BlockT> *L) {
+ LoopBase<BlockT> *&OldLoop = BBMap[BB];
+ assert(OldLoop && "Block not in a loop yet!");
+ OldLoop = L;
+ }
+
+ /// changeTopLevelLoop - Replace the specified loop in the top-level loops
+ /// list with the indicated loop.
+ void changeTopLevelLoop(LoopBase<BlockT> *OldLoop,
+ LoopBase<BlockT> *NewLoop) {
+ typename std::vector<LoopBase<BlockT>*>::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(LoopBase<BlockT> *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 std::map<BlockT *, LoopBase<BlockT>*>::iterator I = BBMap.find(BB);
+ if (I != BBMap.end()) {
+ for (Loop *L = I->second; L; L = L->getParentLoop())
+ L->removeBlockFromLoop(BB);
+
+ BBMap.erase(I);
+ }
+ }
+
+ // Internals
+
+ static bool isNotAlreadyContainedIn(Loop *SubLoop, Loop *ParentLoop) {
+ if (SubLoop == 0) return true;
+ if (SubLoop == ParentLoop) return false;
+ return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
+ }
+
+ void Calculate(DominatorTree &DT) {
+ BlockT *RootNode = DT.getRootNode()->getBlock();
+
+ for (df_iterator<BlockT*> NI = df_begin(RootNode),
+ NE = df_end(RootNode); NI != NE; ++NI)
+ if (LoopBase<BlockT> *L = ConsiderForLoop(*NI, DT))
+ TopLevelLoops.push_back(L);
+ }
+
+ LoopBase<BlockT> *ConsiderForLoop(BlockT *BB, DominatorTree &DT) {
+ if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node?
+
+ std::vector<BlockT *> TodoStack;
+
+ // Scan the predecessors of BB, checking to see if BB dominates any of
+ // them. This identifies backedges which target this node...
+ for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I)
+ if (DT.dominates(BB, *I)) // If BB dominates it's predecessor...
+ TodoStack.push_back(*I);
+
+ if (TodoStack.empty()) return 0; // No backedges to this block...
+
+ // Create a new loop to represent this basic block...
+ LoopBase<BlockT> *L = new LoopBase<BlockT>(BB);
+ BBMap[BB] = L;
+
+ BlockT *EntryBlock = &BB->getParent()->getEntryBlock();
+
+ while (!TodoStack.empty()) { // Process all the nodes in the loop
+ BlockT *X = TodoStack.back();
+ TodoStack.pop_back();
+
+ if (!L->contains(X) && // As of yet unprocessed??
+ DT.dominates(EntryBlock, X)) { // X is reachable from entry block?
+ // Check to see if this block already belongs to a loop. If this occurs
+ // then we have a case where a loop that is supposed to be a child of the
+ // current loop was processed before the current loop. When this occurs,
+ // this child loop gets added to a part of the current loop, making it a
+ // sibling to the current loop. We have to reparent this loop.
+ if (LoopBase<BlockT> *SubLoop =
+ const_cast<LoopBase<BlockT>*>(getLoopFor(X)))
+ if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)) {
+ // Remove the subloop from it's current parent...
+ assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
+ LoopBase<BlockT> *SLP = SubLoop->ParentLoop; // SubLoopParent
+ typename std::vector<LoopBase<BlockT>*>::iterator I =
+ std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop);
+ assert(I != SLP->SubLoops.end() && "SubLoop not a child of parent?");
+ SLP->SubLoops.erase(I); // Remove from parent...
+
+ // Add the subloop to THIS loop...
+ SubLoop->ParentLoop = L;
+ L->SubLoops.push_back(SubLoop);
+ }
+
+ // Normal case, add the block to our loop...
+ L->Blocks.push_back(X);
+
+ // Add all of the predecessors of X to the end of the work stack...
+ TodoStack.insert(TodoStack.end(), pred_begin(X), pred_end(X));
+ }
+ }
+
+ // If there are any loops nested within this loop, create them now!
+ for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
+ E = L->Blocks.end(); I != E; ++I)
+ if (LoopBase<BlockT> *NewLoop = ConsiderForLoop(*I, DT)) {
+ L->SubLoops.push_back(NewLoop);
+ NewLoop->ParentLoop = L;
+ }
+
+ // Add the basic blocks that comprise this loop to the BBMap so that this
+ // loop can be found for them.
+ //
+ for (typename std::vector<BlockT*>::iterator I = L->Blocks.begin(),
+ E = L->Blocks.end(); I != E; ++I) {
+ typename std::map<BlockT*, LoopBase<BlockT>*>::iterator BBMI =
+ BBMap.lower_bound(*I);
+ if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet...
+ BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level
+ }
+
+ // Now that we have a list of all of the child loops of this loop, check to
+ // see if any of them should actually be nested inside of each other. We can
+ // accidentally pull loops our of their parents, so we must make sure to
+ // organize the loop nests correctly now.
+ {
+ std::map<BlockT*, LoopBase<BlockT>*> ContainingLoops;
+ for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
+ LoopBase<BlockT> *Child = L->SubLoops[i];
+ assert(Child->getParentLoop() == L && "Not proper child loop?");
+
+ if (LoopBase<BlockT> *ContainingLoop =
+ ContainingLoops[Child->getHeader()]) {
+ // If there is already a loop which contains this loop, move this loop
+ // into the containing loop.
+ MoveSiblingLoopInto(Child, ContainingLoop);
+ --i; // The loop got removed from the SubLoops list.
+ } else {
+ // This is currently considered to be a top-level loop. Check to see if
+ // any of the contained blocks are loop headers for subloops we have
+ // already processed.
+ for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) {
+ LoopBase<BlockT> *&BlockLoop = ContainingLoops[Child->Blocks[b]];
+ if (BlockLoop == 0) { // Child block not processed yet...
+ BlockLoop = Child;
+ } else if (BlockLoop != Child) {
+ LoopBase<BlockT> *SubLoop = BlockLoop;
+ // Reparent all of the blocks which used to belong to BlockLoops
+ for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j)
+ ContainingLoops[SubLoop->Blocks[j]] = Child;
+
+ // There is already a loop which contains this block, that means
+ // that we should reparent the loop which the block is currently
+ // considered to belong to to be a child of this loop.
+ MoveSiblingLoopInto(SubLoop, Child);
+ --i; // We just shrunk the SubLoops list.
+ }
+ }
+ }
+ }
+ }
+
+ return L;
+ }
+
+ /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside of
+ /// the NewParent Loop, instead of being a sibling of it.
+ void MoveSiblingLoopInto(LoopBase<BlockT> *NewChild,
+ LoopBase<BlockT> *NewParent) {
+ LoopBase<BlockT> *OldParent = NewChild->getParentLoop();
+ assert(OldParent && OldParent == NewParent->getParentLoop() &&
+ NewChild != NewParent && "Not sibling loops!");
+
+ // Remove NewChild from being a child of OldParent
+ typename std::vector<LoopBase<BlockT>*>::iterator I =
+ std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), NewChild);
+ assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??");
+ OldParent->SubLoops.erase(I); // Remove from parent's subloops list
+ NewChild->ParentLoop = 0;
+
+ InsertLoopInto(NewChild, NewParent);
+ }
+
+ /// InsertLoopInto - This inserts loop L into the specified parent loop. If the
+ /// parent loop contains a loop which should contain L, the loop gets inserted
+ /// into L instead.
+ void InsertLoopInto(LoopBase<BlockT> *L, LoopBase<BlockT> *Parent) {
+ BlockT *LHeader = L->getHeader();
+ assert(Parent->contains(LHeader) && "This loop should not be inserted here!");
+
+ // Check to see if it belongs in a child loop...
+ for (unsigned i = 0, e = Parent->SubLoops.size(); i != e; ++i)
+ if (Parent->SubLoops[i]->contains(LHeader)) {
+ InsertLoopInto(L, Parent->SubLoops[i]);
+ return;
+ }
+
+ // If not, insert it here!
+ Parent->SubLoops.push_back(L);
+ L->ParentLoop = Parent;
+ }
+
+ // Debugging
+
+ void print(std::ostream &OS, const Module* ) const {
+ for (unsigned i = 0; i < TopLevelLoops.size(); ++i)
+ TopLevelLoops[i]->print(OS);
+ #if 0
+ for (std::map<BasicBlock*, Loop*>::const_iterator I = BBMap.begin(),
+ E = BBMap.end(); I != E; ++I)
+ OS << "BB '" << I->first->getName() << "' level = "
+ << I->second->getLoopDepth() << "\n";
+ #endif
+ }
+};
+
+class LoopInfo : public FunctionPass {
+ LoopInfoBase<BasicBlock>* LI;
+ friend class LoopBase<BasicBlock>;
+
+ LoopInfoBase<BasicBlock>& getBase() { return *LI; }
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopInfo() : FunctionPass(intptr_t(&ID)) {
+ LI = new LoopInfoBase<BasicBlock>();
+ }
+
+ ~LoopInfo() { LI->releaseMemory(); }
+
+ /// iterator/begin/end - The interface to the top-level loops in the current
+ /// function.
+ ///
+ typedef std::vector<Loop*>::const_iterator iterator;
+ inline iterator begin() const { return LI->begin(); }
+ inline iterator end() const { return LI->end(); }
+
+ /// 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...
+ ///
+ 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 releaseMemory() { LI->releaseMemory(); }
+
+ virtual void print(std::ostream &O, const Module* M = 0) const {
+ if (O) LI->print(O, M);
+ }
- /// getAnalysisUsage - Requires dominator sets
- ///
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- static void stub(); // Noop
-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);
+ }
+};
+
+
+// Allow clients to walk the list of nested loops...
+template <> struct GraphTraits<const Loop*> {
+ typedef const Loop NodeType;
+ typedef std::vector<Loop*>::const_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 std::vector<Loop*>::const_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();
+ }
+};
+
+template<class BlockT>
+void LoopBase<BlockT>::addBasicBlockToLoop(BlockT *NewBB,
+ LoopInfo &LI) {
+ assert((Blocks.empty() || LI[getHeader()] == this) &&
+ "Incorrect LI specified for this loop!");
+ assert(NewBB && "Cannot add a null basic block to the loop!");
+ assert(LI[NewBB] == 0 && "BasicBlock already in the loop!");
+
+ LoopInfoBase<BasicBlock>& LIB = LI.getBase();
+
+ // Add the loop mapping to the LoopInfo object...
+ LIB.BBMap[NewBB] = this;
+
+ // Add the basic block to this loop and all parent loops...
+ LoopBase<BlockT> *L = this;
+ while (L) {
+ L->Blocks.push_back(NewBB);
+ L = L->getParentLoop();
+ }
+}
+
+} // End llvm namespace
// Make sure that any clients of this file link in LoopInfo.cpp
-static IncludeFile
-LOOP_INFO_INCLUDE_FILE((void*)&LoopInfo::stub);
+FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo)
#endif
projects / oota-llvm.git / blobdiff