//===----------------------------------------------------------------------===//
//
// 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
+// 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
// * whether or not a particular block branches out of the loop
// * the successor blocks of the loop
// * the loop depth
-// * the trip count
// * etc...
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_LOOP_INFO_H
#define LLVM_ANALYSIS_LOOP_INFO_H
-#include "llvm/Pass.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 "llvm/Support/CFG.h"
-#include "llvm/Support/Streams.h"
+#include "llvm/Support/raw_ostream.h"
#include <algorithm>
-#include <ostream>
+#include <map>
namespace llvm {
template<typename T>
-static void RemoveFromVector(std::vector<T*> &V, T *N) {
+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;
// 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> &);
+ 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) {}
BlockT *getHeader() const { return Blocks.front(); }
LoopT *getParentLoop() const { return ParentLoop; }
- /// contains - Return true if the specified basic block is in this loop
+ /// setParentLoop is a raw interface for bypassing addChildLoop.
+ void setParentLoop(LoopT *L) { ParentLoop = L; }
+
+ /// 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());
+ }
+
+ /// 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(); }
- /// isLoopExit - True if terminator in the block can branch to another block
- /// that is outside of the current loop.
+ /// 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 isLoopExit(const BlockT *BB) const {
+ bool isLoopExiting(const BlockT *BB) const {
typedef GraphTraits<BlockT*> BlockTraits;
for (typename BlockTraits::ChildIteratorType SI =
BlockTraits::child_begin(const_cast<BlockT*>(BB)),
/// 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());
-
- 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;
- }
- }
+ void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
/// 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;
- }
+ 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 {
- // 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);
- }
+ void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
/// 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;
- }
+ BlockT *getExitBlock() 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 is in canonical form.
- ///
- 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);
- }
- }
- }
- }
+ /// Edge type.
+ typedef std::pair<const BlockT*, const BlockT*> Edge;
- /// 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;
- }
+ /// 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
///
/// 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();
- 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;
- }
-
- // 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.
+ BlockT *getLoopPreheader() const;
- // If there is exactly one preheader, return it. If there was zero, then
- // Out is still null.
- return Out;
- }
+ /// 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.
- /// 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;
- }
+ BlockT *getLoopLatch() const;
//===--------------------------------------------------------------------===//
// APIs for updating loop information after changing the CFG
/// 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) {
- 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);
- }
+ 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.
}
/// 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 verifyLoop() const;
- void print(std::ostream &OS, unsigned Depth = 0) const {
- OS << std::string(Depth*2, ' ') << "Loop at depth " << getLoopDepth()
- << " containing: ";
+ /// verifyLoop - Verify loop structure of this loop and all nested loops.
+ void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
- 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";
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
- 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 {
- print(cerr);
- }
-
protected:
friend class LoopInfoBase<BlockT, LoopT>;
explicit LoopBase(BlockT *BB) : ParentLoop(0) {
}
};
+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() {}
///
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
///
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;
+ /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ bool isLCSSAForm(DominatorTree &DT) 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!).
+ /// 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.
///
- /// 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;
+ void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
- /// isLCSSAForm - Return true if the Loop is in LCSSA form
- bool isLCSSAForm() 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>;
template<class BlockT, class LoopT>
class LoopInfoBase {
// BBMap - Mapping of basic blocks to the inner most loop they occur in
- std::map<BlockT *, LoopT *> BBMap;
+ DenseMap<BlockT *, LoopT *> BBMap;
std::vector<LoopT *> TopLevelLoops;
friend class LoopBase<BlockT, LoopT>;
+ friend class LoopInfo;
- void operator=(const LoopInfoBase &); // do not implement
- LoopInfoBase(const LoopInfo &); // do not implement
+ void operator=(const LoopInfoBase &) LLVM_DELETED_FUNCTION;
+ LoopInfoBase(const LoopInfo &) LLVM_DELETED_FUNCTION;
public:
LoopInfoBase() { }
~LoopInfoBase() { releaseMemory(); }
-
+
void releaseMemory() {
for (typename std::vector<LoopT *>::iterator I =
TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I)
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<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 {
- typename std::map<BlockT *, LoopT *>::const_iterator I=
- BBMap.find(const_cast<BlockT*>(BB));
- return I != BBMap.end() ? I->second : 0;
+ return BBMap.lookup(const_cast<BlockT*>(BB));
}
-
+
/// operator[] - same as getLoopFor...
///
const LoopT *operator[](const BlockT *BB) const {
return getLoopFor(BB);
}
-
+
/// getLoopDepth - Return the loop nesting level of the specified block. A
/// depth of 0 means the block is not inside any loop.
///
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.
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;
+ 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,
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);
+ 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);
}
-
- 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;
- }
+ /// Create the loop forest using a stable algorithm.
+ void Analyze(DominatorTreeBase<BlockT> &DomTree);
- // 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
- }
+
+ void print(raw_ostream &OS) const;
};
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
+#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
+ 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) {}
+ LoopInfo() : FunctionPass(ID) {
+ initializeLoopInfoPass(*PassRegistry::getPassRegistry());
+ }
LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; }
/// 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
///
virtual bool runOnFunction(Function &F);
+ virtual void verifyAnalysis() const;
+
virtual void releaseMemory() { LI.releaseMemory(); }
- virtual void print(std::ostream &O, const Module* M = 0) const {
- LI.print(O, M);
- }
+ virtual void print(raw_ostream &O, const Module* M = 0) const;
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
LI.removeBlock(BB);
}
- static bool isNotAlreadyContainedIn(const Loop *SubLoop,
- const Loop *ParentLoop) {
- return
- LoopInfoBase<BasicBlock, Loop>::isNotAlreadyContainedIn(SubLoop,
- ParentLoop);
+ /// 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()));
}
};
}
};
-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;
-
- // 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