//
// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#define LLVM_ANALYSIS_LOOP_INFO_H
#include "llvm/Pass.h"
+#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/GraphTraits.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>
namespace llvm {
+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);
+}
+
class DominatorTree;
class LoopInfo;
-class PHINode;
-class Instruction;
+class Loop;
+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
+/// 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
-
- Loop(const Loop &); // DO NOT IMPLEMENT
- const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
+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;
+
+ // DO NOT IMPLEMENT
+ LoopBase(const LoopBase<BlockT, LoopT> &);
+ // DO NOT IMPLEMENT
+ const LoopBase<BlockT, LoopT>&operator=(const LoopBase<BlockT, LoopT> &);
public:
/// Loop ctor - This creates an empty loop.
- Loop() : ParentLoop(0) {}
- ~Loop() {
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
+ LoopBase() : ParentLoop(0) {}
+ ~LoopBase() {
+ for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
delete SubLoops[i];
}
+ /// 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 = 0;
- for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop)
+ unsigned D = 1;
+ for (const LoopT *CurLoop = ParentLoop; CurLoop;
+ CurLoop = CurLoop->ParentLoop)
++D;
return D;
}
- BasicBlock *getHeader() const { return Blocks.front(); }
- Loop *getParentLoop() const { return ParentLoop; }
+ BlockT *getHeader() const { return Blocks.front(); }
+ LoopT *getParentLoop() const { return ParentLoop; }
- /// contains - Return true of the specified basic block is in this loop
+ /// contains - Return true if the specified basic block is in this loop
///
- bool contains(const BasicBlock *BB) const;
+ bool contains(const BlockT *BB) const {
+ return std::find(block_begin(), block_end(), BB) != block_end();
+ }
/// iterator/begin/end - Return the loops contained entirely within this loop.
///
- const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
- typedef std::vector<Loop*>::const_iterator iterator;
+ const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
+ typedef typename std::vector<LoopT *>::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; }
- typedef std::vector<BasicBlock*>::const_iterator block_iterator;
+ 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 BasicBlock *BB) const;
+ bool isLoopExit(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;
-
- /// isLoopInvariant - Return true if the specified value is loop invariant
- ///
- bool isLoopInvariant(Value *V) const;
+ 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.
/// outside of the loop. These are the blocks _inside of the current loop_
/// which branch out. The returned list is always unique.
///
- void getExitingBlocks(std::vector<BasicBlock*> &Blocks) const;
+ 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());
+
+ typedef GraphTraits<BlockT*> BlockTraits;
+ for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
+ for (typename BlockTraits::ChildIteratorType I =
+ BlockTraits::child_begin(*BI), E = BlockTraits::child_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;
+ }
+ }
+
+ /// getExitingBlock - If getExitingBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ BlockT *getExitingBlock() const {
+ SmallVector<BlockT*, 8> ExitingBlocks;
+ getExitingBlocks(ExitingBlocks);
+ if (ExitingBlocks.size() == 1)
+ return ExitingBlocks[0];
+ return 0;
+ }
/// 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(std::vector<BasicBlock*> &Blocks) const;
+ 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());
+
+ typedef GraphTraits<BlockT*> BlockTraits;
+ for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI)
+ for (typename BlockTraits::ChildIteratorType I =
+ BlockTraits::child_begin(*BI), E = BlockTraits::child_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);
+ }
+
+ /// getExitBlock - If getExitBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ BlockT *getExitBlock() const {
+ SmallVector<BlockT*, 8> ExitBlocks;
+ getExitBlocks(ExitBlocks);
+ if (ExitBlocks.size() == 1)
+ return ExitBlocks[0];
+ return 0;
+ }
/// 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.
///
- void getUniqueExitBlocks(std::vector<BasicBlock*> &ExitBlocks) 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 (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) {
+
+ BlockT *current = *BI;
+ switchExitBlocks.clear();
+
+ typedef GraphTraits<BlockT*> BlockTraits;
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename BlockTraits::ChildIteratorType I =
+ BlockTraits::child_begin(*BI), E = BlockTraits::child_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;
+
+ typename InvBlockTraits::ChildIteratorType PI =
+ InvBlockTraits::child_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 (std::distance(BlockTraits::child_begin(current),
+ BlockTraits::child_end(current)) <= 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);
+ }
+ }
+ }
+ }
+
+ /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
+ /// block, return that block. Otherwise return null.
+ BlockT *getUniqueExitBlock() const {
+ SmallVector<BlockT*, 8> UniqueExitBlocks;
+ getUniqueExitBlocks(UniqueExitBlocks);
+ if (UniqueExitBlocks.size() == 1)
+ return UniqueExitBlocks[0];
+ return 0;
+ }
/// 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
///
/// This method returns null if there is no preheader for the loop.
///
- BasicBlock *getLoopPreheader() const;
+ 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();
+ typedef GraphTraits<BlockT*> BlockTraits;
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType PI =
+ InvBlockTraits::child_begin(Header),
+ PE = InvBlockTraits::child_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;
+ }
- /// 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.
- BasicBlock *getLoopLatch() 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.
- ///
- PHINode *getCanonicalInductionVariable() const;
+ // Make sure there is only one exit out of the preheader.
+ assert(Out && "Header of loop has no predecessors from outside loop?");
+ typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out);
+ ++SI;
+ if (SI != BlockTraits::child_end(Out))
+ return 0; // Multiple exits from the block, must not be a preheader.
- /// 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.
- ///
- Instruction *getCanonicalInductionVariableIncrement() const;
+ // If there is exactly one preheader, return it. If there was zero, then
+ // Out is still null.
+ return Out;
+ }
- /// 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.
- ///
- Value *getTripCount() const;
-
- /// isLCSSAForm - Return true if the Loop is in LCSSA form
- bool isLCSSAForm() 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.
+ /// 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();
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ typename InvBlockTraits::ChildIteratorType PI =
+ InvBlockTraits::child_begin(Header);
+ typename InvBlockTraits::ChildIteratorType PE =
+ InvBlockTraits::child_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;
+ }
//===--------------------------------------------------------------------===//
// APIs for updating loop information after changing the CFG
/// 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, 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(Loop *OldChild, Loop *NewChild);
+ void replaceChildLoopWith(LoopT *OldChild,
+ LoopT *NewChild) {
+ assert(OldChild->ParentLoop == this && "This loop is already broken!");
+ assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ typename std::vector<LoopT *>::iterator I =
+ std::find(SubLoops.begin(), SubLoops.end(), OldChild);
+ assert(I != SubLoops.end() && "OldChild not in loop!");
+ *I = NewChild;
+ OldChild->ParentLoop = 0;
+ NewChild->ParentLoop = static_cast<LoopT *>(this);
+ }
/// addChildLoop - Add the specified loop to be a child of this loop. This
/// updates the loop depth of the new child.
///
- void addChildLoop(Loop *NewChild);
+ void addChildLoop(LoopT *NewChild) {
+ assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!");
+ NewChild->ParentLoop = static_cast<LoopT *>(this);
+ SubLoops.push_back(NewChild);
+ }
/// 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.
- Loop *removeChildLoop(iterator OldChild);
+ 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(BasicBlock *BB) {
+ 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(BasicBlock *BB) {
+ void moveToHeader(BlockT *BB) {
if (Blocks[0] == BB) return;
for (unsigned i = 0; ; ++i) {
assert(i != Blocks.size() && "Loop does not contain BB!");
/// 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(BasicBlock *BB);
+ 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 (iterator I = SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
+ (*I)->verifyLoop();
+#endif
+ }
- void print(std::ostream &O, unsigned Depth = 0) const;
+ void print(std::ostream &OS, unsigned Depth = 0) const {
+ OS << std::string(Depth*2, ' ') << "Loop at depth " << getLoopDepth()
+ << " containing: ";
+
+ for (unsigned i = 0; i < getBlocks().size(); ++i) {
+ if (i) OS << ",";
+ BlockT *BB = getBlocks()[i];
+ WriteAsOperand(OS, BB, false);
+ if (BB == getHeader()) OS << "<header>";
+ if (BB == getLoopLatch()) OS << "<latch>";
+ if (isLoopExit(BB)) OS << "<exit>";
+ }
+ OS << "\n";
+
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ (*I)->print(OS, Depth+2);
+ }
+
void print(std::ostream *O, unsigned Depth = 0) const {
if (O) print(*O, Depth);
}
- void dump() const;
-private:
- friend class LoopInfo;
- Loop(BasicBlock *BB) : ParentLoop(0) {
+
+ void dump() const {
+ print(cerr);
+ }
+
+protected:
+ friend class LoopInfoBase<BlockT, LoopT>;
+ explicit LoopBase(BlockT *BB) : ParentLoop(0) {
Blocks.push_back(BB);
}
};
+class Loop : public LoopBase<BasicBlock, Loop> {
+public:
+ Loop() {}
+ /// isLoopInvariant - Return true if the specified value is loop invariant
+ ///
+ bool isLoopInvariant(Value *V) const;
+
+ /// isLoopInvariant - Return true if the specified instruction is
+ /// loop-invariant.
+ ///
+ bool isLoopInvariant(Instruction *I) const;
+
+ /// makeLoopInvariant - If the given value is an instruciton 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;
+
+ /// 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.
+ ///
+ Instruction *getCanonicalInductionVariableIncrement() const;
+
+ /// 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.
+ ///
+ /// The IndVarSimplify pass transforms loops to have a form that this
+ /// function easily understands.
+ ///
+ Value *getTripCount() const;
+
+ /// getSmallConstantTripCount - Returns the trip count of this loop as a
+ /// normal unsigned value, if possible. Returns 0 if the trip count is unknown
+ /// of not constant. Will also return 0 if the trip count is very large
+ /// (>= 2^32)
+ unsigned getSmallConstantTripCount() const;
+
+ /// getSmallConstantTripMultiple - Returns the largest constant divisor of the
+ /// trip count of this loop as a normal unsigned value, if possible. This
+ /// means that the actual trip count is always a multiple of the returned
+ /// value (don't forget the trip count could very well be zero as well!).
+ ///
+ /// Returns 1 if the trip count is unknown or not guaranteed to be the
+ /// multiple of a constant (which is also the case if the trip count is simply
+ /// constant, use getSmallConstantTripCount for that case), Will also return 1
+ /// if the trip count is very large (>= 2^32).
+ unsigned getSmallConstantTripMultiple() const;
+
+ /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ bool isLCSSAForm() 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 {
+
+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;
- friend class Loop;
-public:
- static char ID; // Pass identification, replacement for typeid
+ std::map<BlockT *, LoopT *> BBMap;
+ std::vector<LoopT *> TopLevelLoops;
+ friend class LoopBase<BlockT, LoopT>;
- LoopInfo() : FunctionPass((intptr_t)&ID) {}
- ~LoopInfo() { releaseMemory(); }
+ void operator=(const LoopInfoBase &); // do not implement
+ LoopInfoBase(const LoopInfo &); // do not implement
+public:
+ LoopInfoBase() { }
+ ~LoopInfoBase() { 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...
+ BBMap.clear(); // Reset internal state of analysis
+ TopLevelLoops.clear();
+ }
+
/// iterator/begin/end - The interface to the top-level loops in the current
/// function.
///
- typedef std::vector<Loop*>::const_iterator iterator;
+ typedef typename std::vector<LoopT *>::const_iterator iterator;
iterator begin() const { return TopLevelLoops.begin(); }
iterator end() const { return TopLevelLoops.end(); }
-
+ 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.
///
- Loop *getLoopFor(const BasicBlock *BB) const {
- std::map<BasicBlock *, Loop*>::const_iterator I=
- BBMap.find(const_cast<BasicBlock*>(BB));
+ LoopT *getLoopFor(const BlockT *BB) const {
+ typename std::map<BlockT *, LoopT *>::const_iterator I=
+ BBMap.find(const_cast<BlockT*>(BB));
return I != BBMap.end() ? I->second : 0;
}
-
+
/// operator[] - same as getLoopFor...
///
- const Loop *operator[](const BasicBlock *BB) const {
+ const LoopT *operator[](const BlockT *BB) const {
return getLoopFor(BB);
}
-
- /// getLoopDepth - Return the loop nesting level of the specified block...
+
+ /// 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 BasicBlock *BB) const {
- const Loop *L = getLoopFor(BB);
+ unsigned getLoopDepth(const BlockT *BB) const {
+ const LoopT *L = getLoopFor(BB);
return L ? L->getLoopDepth() : 0;
}
// isLoopHeader - True if the block is a loop header node
- bool isLoopHeader(BasicBlock *BB) const {
- const Loop *L = getLoopFor(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) {
+ LoopT *&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(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 std::map<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);
+ }
+
+ void Calculate(DominatorTreeBase<BlockT> &DT) {
+ BlockT *RootNode = DT.getRootNode()->getBlock();
+
+ for (df_iterator<BlockT*> NI = df_begin(RootNode),
+ NE = df_end(RootNode); NI != NE; ++NI)
+ if (LoopT *L = ConsiderForLoop(*NI, DT))
+ TopLevelLoops.push_back(L);
+ }
+
+ LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase<BlockT> &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...
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType I =
+ InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_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...
+ LoopT *L = new LoopT(BB);
+ BBMap[BB] = L;
+
+ BlockT *EntryBlock = BB->getParent()->begin();
+
+ 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 (LoopT *SubLoop =
+ const_cast<LoopT *>(getLoopFor(X)))
+ if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){
+ // Remove the subloop from it's current parent...
+ assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L);
+ LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent
+ typename std::vector<LoopT *>::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);
+
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+
+ // Add all of the predecessors of X to the end of the work stack...
+ TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X),
+ InvBlockTraits::child_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 (LoopT *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*, LoopT *>::iterator BBMI = BBMap.find(*I);
+ if (BBMI == BBMap.end()) // 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 *, LoopT *> ContainingLoops;
+ for (unsigned i = 0; i != L->SubLoops.size(); ++i) {
+ LoopT *Child = L->SubLoops[i];
+ assert(Child->getParentLoop() == L && "Not proper child loop?");
+
+ if (LoopT *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) {
+ LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]];
+ if (BlockLoop == 0) { // Child block not processed yet...
+ BlockLoop = Child;
+ } else if (BlockLoop != Child) {
+ LoopT *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(LoopT *NewChild,
+ LoopT *NewParent) {
+ LoopT *OldParent = NewChild->getParentLoop();
+ assert(OldParent && OldParent == NewParent->getParentLoop() &&
+ NewChild != NewParent && "Not sibling loops!");
+
+ // Remove NewChild from being a child of OldParent
+ typename std::vector<LoopT *>::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(LoopT *L, LoopT *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 = static_cast<unsigned>(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*, LoopT*>::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, Loop> LI;
+ friend class LoopBase<BasicBlock, Loop>;
+
+ void operator=(const LoopInfo &); // do not implement
+ LoopInfo(const LoopInfo &); // do not implement
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopInfo() : FunctionPass(&ID) {}
+
+ 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;
+ inline iterator begin() const { return LI.begin(); }
+ inline iterator end() const { return LI.end(); }
+ 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();
+ virtual void releaseMemory() { LI.releaseMemory(); }
- void print(std::ostream &O, const Module* = 0) const;
- void print(std::ostream *O, const Module* M = 0) const {
- if (O) print(*O, M);
+ virtual void print(std::ostream &O, const Module* M = 0) const {
+ LI.print(O, M);
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
/// 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.
- Loop *removeLoop(iterator I);
+ 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.
- void changeLoopFor(BasicBlock *BB, Loop *L);
+ 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.
- void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop);
+ inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) {
+ LI.changeTopLevelLoop(OldLoop, NewLoop);
+ }
/// addTopLevelLoop - This adds the specified loop to the collection of
/// top-level loops.
- void addTopLevelLoop(Loop *New) {
- assert(New->getParentLoop() == 0 && "Loop already in subloop!");
- TopLevelLoops.push_back(New);
+ 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);
+ void removeBlock(BasicBlock *BB) {
+ LI.removeBlock(BB);
+ }
-private:
- void Calculate(DominatorTree &DT);
- Loop *ConsiderForLoop(BasicBlock *BB, DominatorTree &DT);
- void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent);
- void InsertLoopInto(Loop *L, Loop *Parent);
+ static bool isNotAlreadyContainedIn(const Loop *SubLoop,
+ const Loop *ParentLoop) {
+ return
+ LoopInfoBase<BasicBlock, Loop>::isNotAlreadyContainedIn(SubLoop,
+ ParentLoop);
+ }
};
// 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;
+ typedef LoopInfo::iterator ChildIteratorType;
static NodeType *getEntryNode(const Loop *L) { return L; }
static inline ChildIteratorType child_begin(NodeType *N) {
template <> struct GraphTraits<Loop*> {
typedef Loop NodeType;
- typedef std::vector<Loop*>::const_iterator ChildIteratorType;
+ typedef LoopInfo::iterator ChildIteratorType;
static NodeType *getEntryNode(Loop *L) { return L; }
static inline ChildIteratorType child_begin(NodeType *N) {
}
};
-} // End llvm namespace
+template<class BlockT, class LoopT>
+void
+LoopBase<BlockT, LoopT>::addBasicBlockToLoop(BlockT *NewBB,
+ LoopInfoBase<BlockT, LoopT> &LIB) {
+ assert((Blocks.empty() || LIB[getHeader()] == this) &&
+ "Incorrect LI specified for this loop!");
+ assert(NewBB && "Cannot add a null basic block to the loop!");
+ assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!");
+
+ LoopT *L = static_cast<LoopT *>(this);
+
+ // Add the loop mapping to the LoopInfo object...
+ LIB.BBMap[NewBB] = L;
-// Make sure that any clients of this file link in LoopInfo.cpp
-FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo)
+ // Add the basic block to this loop and all parent loops...
+ while (L) {
+ L->Blocks.push_back(NewBB);
+ L = L->getParentLoop();
+ }
+}
+
+} // End llvm namespace
#endif
projects / oota-llvm.git / blobdiff