/src/freebsd/contrib/llvm/lib/Analysis/LoopInfo.cpp
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- //===- LoopInfo.cpp - Natural Loop Calculator -----------------------------===//
- //
- // The LLVM Compiler Infrastructure
- //
- // This file is distributed under the University of Illinois Open Source
- // License. See LICENSE.TXT for details.
- //
- //===----------------------------------------------------------------------===//
- //
- // This file defines the LoopInfo class that is used to identify natural loops
- // and determine the loop depth of various nodes of the CFG. Note that the
- // loops identified may actually be several natural loops that share the same
- // header node... not just a single natural loop.
- //
- //===----------------------------------------------------------------------===//
- #include "llvm/Analysis/LoopInfo.h"
- #include "llvm/Constants.h"
- #include "llvm/Instructions.h"
- #include "llvm/Analysis/Dominators.h"
- #include "llvm/Analysis/LoopIterator.h"
- #include "llvm/Assembly/Writer.h"
- #include "llvm/Support/CFG.h"
- #include "llvm/Support/CommandLine.h"
- #include "llvm/Support/Debug.h"
- #include "llvm/ADT/DepthFirstIterator.h"
- #include "llvm/ADT/SmallPtrSet.h"
- #include <algorithm>
- using namespace llvm;
- // Always verify loopinfo if expensive checking is enabled.
- #ifdef XDEBUG
- static bool VerifyLoopInfo = true;
- #else
- static bool VerifyLoopInfo = false;
- #endif
- static cl::opt<bool,true>
- VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo),
- cl::desc("Verify loop info (time consuming)"));
- char LoopInfo::ID = 0;
- INITIALIZE_PASS_BEGIN(LoopInfo, "loops", "Natural Loop Information", true, true)
- INITIALIZE_PASS_DEPENDENCY(DominatorTree)
- INITIALIZE_PASS_END(LoopInfo, "loops", "Natural Loop Information", true, true)
- //===----------------------------------------------------------------------===//
- // Loop implementation
- //
- /// isLoopInvariant - Return true if the specified value is loop invariant
- ///
- bool Loop::isLoopInvariant(Value *V) const {
- if (Instruction *I = dyn_cast<Instruction>(V))
- return !contains(I);
- return true; // All non-instructions are loop invariant
- }
- /// hasLoopInvariantOperands - Return true if all the operands of the
- /// specified instruction are loop invariant.
- bool Loop::hasLoopInvariantOperands(Instruction *I) const {
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (!isLoopInvariant(I->getOperand(i)))
- return false;
- return true;
- }
- /// 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 Loop::makeLoopInvariant(Value *V, bool &Changed,
- Instruction *InsertPt) const {
- if (Instruction *I = dyn_cast<Instruction>(V))
- return makeLoopInvariant(I, Changed, InsertPt);
- return true; // All non-instructions are loop-invariant.
- }
- /// 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 Loop::makeLoopInvariant(Instruction *I, bool &Changed,
- Instruction *InsertPt) const {
- // Test if the value is already loop-invariant.
- if (isLoopInvariant(I))
- return true;
- if (!I->isSafeToSpeculativelyExecute())
- return false;
- if (I->mayReadFromMemory())
- return false;
- // The landingpad instruction is immobile.
- if (isa<LandingPadInst>(I))
- return false;
- // Determine the insertion point, unless one was given.
- if (!InsertPt) {
- BasicBlock *Preheader = getLoopPreheader();
- // Without a preheader, hoisting is not feasible.
- if (!Preheader)
- return false;
- InsertPt = Preheader->getTerminator();
- }
- // Don't hoist instructions with loop-variant operands.
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (!makeLoopInvariant(I->getOperand(i), Changed, InsertPt))
- return false;
- // Hoist.
- I->moveBefore(InsertPt);
- Changed = true;
- return true;
- }
- /// 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 *Loop::getCanonicalInductionVariable() const {
- BasicBlock *H = getHeader();
- BasicBlock *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 (BasicBlock::iterator I = H->begin(); isa<PHINode>(I); ++I) {
- PHINode *PN = cast<PHINode>(I);
- if (ConstantInt *CI =
- dyn_cast<ConstantInt>(PN->getIncomingValueForBlock(Incoming)))
- if (CI->isNullValue())
- 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;
- }
- /// 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 *Loop::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.
- PHINode *IV = getCanonicalInductionVariable();
- if (IV == 0 || IV->getNumIncomingValues() != 2) return 0;
- bool P0InLoop = contains(IV->getIncomingBlock(0));
- Value *Inc = IV->getIncomingValue(!P0InLoop);
- BasicBlock *BackedgeBlock = IV->getIncomingBlock(!P0InLoop);
- 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;
- }
- /// getSmallConstantTripCount - Returns the trip count of this loop as a
- /// normal unsigned value, if possible. Returns 0 if the trip count is unknown
- /// or not constant. Will also return 0 if the trip count is very large
- /// (>= 2^32)
- unsigned Loop::getSmallConstantTripCount() const {
- Value* TripCount = this->getTripCount();
- if (TripCount) {
- if (ConstantInt *TripCountC = dyn_cast<ConstantInt>(TripCount)) {
- // Guard against huge trip counts.
- if (TripCountC->getValue().getActiveBits() <= 32) {
- return (unsigned)TripCountC->getZExtValue();
- }
- }
- }
- return 0;
- }
- /// 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 Loop::getSmallConstantTripMultiple() const {
- Value* TripCount = this->getTripCount();
- // This will hold the ConstantInt result, if any
- ConstantInt *Result = NULL;
- if (TripCount) {
- // See if the trip count is constant itself
- Result = dyn_cast<ConstantInt>(TripCount);
- // if not, see if it is a multiplication
- if (!Result)
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TripCount)) {
- switch (BO->getOpcode()) {
- case BinaryOperator::Mul:
- Result = dyn_cast<ConstantInt>(BO->getOperand(1));
- break;
- case BinaryOperator::Shl:
- if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
- if (CI->getValue().getActiveBits() <= 5)
- return 1u << CI->getZExtValue();
- break;
- default:
- break;
- }
- }
- }
- // Guard against huge trip counts.
- if (Result && Result->getValue().getActiveBits() <= 32) {
- return (unsigned)Result->getZExtValue();
- } else {
- return 1;
- }
- }
- /// isLCSSAForm - Return true if the Loop is in LCSSA form
- bool Loop::isLCSSAForm(DominatorTree &DT) const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallPtrSet<BasicBlock*, 16> LoopBBs(block_begin(), block_end());
- for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) {
- BasicBlock *BB = *BI;
- for (BasicBlock::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) {
- User *U = *UI;
- BasicBlock *UserBB = cast<Instruction>(U)->getParent();
- if (PHINode *P = dyn_cast<PHINode>(U))
- UserBB = P->getIncomingBlock(UI);
- // Check the current block, as a fast-path, before checking whether
- // the use is anywhere in the loop. Most values are used in the same
- // block they are defined in. Also, blocks not reachable from the
- // entry are special; uses in them don't need to go through PHIs.
- if (UserBB != BB &&
- !LoopBBs.count(UserBB) &&
- DT.isReachableFromEntry(UserBB))
- return false;
- }
- }
- return true;
- }
- /// isLoopSimplifyForm - Return true if the Loop is in the form that
- /// the LoopSimplify form transforms loops to, which is sometimes called
- /// normal form.
- bool Loop::isLoopSimplifyForm() const {
- // Normal-form loops have a preheader, a single backedge, and all of their
- // exits have all their predecessors inside the loop.
- return getLoopPreheader() && getLoopLatch() && hasDedicatedExits();
- }
- /// hasDedicatedExits - Return true if no exit block for the loop
- /// has a predecessor that is outside the loop.
- bool Loop::hasDedicatedExits() const {
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallPtrSet<BasicBlock *, 16> LoopBBs(block_begin(), block_end());
- // Each predecessor of each exit block of a normal loop is contained
- // within the loop.
- SmallVector<BasicBlock *, 4> ExitBlocks;
- getExitBlocks(ExitBlocks);
- for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
- for (pred_iterator PI = pred_begin(ExitBlocks[i]),
- PE = pred_end(ExitBlocks[i]); PI != PE; ++PI)
- if (!LoopBBs.count(*PI))
- return false;
- // All the requirements are met.
- return true;
- }
- /// getUniqueExitBlocks - Return all unique successor blocks of this loop.
- /// These are the blocks _outside of the current loop_ which are branched to.
- /// This assumes that loop exits are in canonical form.
- ///
- void
- Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const {
- assert(hasDedicatedExits() &&
- "getUniqueExitBlocks assumes the loop has canonical form exits!");
- // Sort the blocks vector so that we can use binary search to do quick
- // lookups.
- SmallVector<BasicBlock *, 128> LoopBBs(block_begin(), block_end());
- std::sort(LoopBBs.begin(), LoopBBs.end());
- SmallVector<BasicBlock *, 32> switchExitBlocks;
- for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) {
- BasicBlock *current = *BI;
- switchExitBlocks.clear();
- for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I) {
- // If block is inside the loop then it is not a exit block.
- if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
- continue;
- pred_iterator PI = pred_begin(*I);
- BasicBlock *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(succ_begin(current), succ_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.
- BasicBlock *Loop::getUniqueExitBlock() const {
- SmallVector<BasicBlock *, 8> UniqueExitBlocks;
- getUniqueExitBlocks(UniqueExitBlocks);
- if (UniqueExitBlocks.size() == 1)
- return UniqueExitBlocks[0];
- return 0;
- }
- void Loop::dump() const {
- print(dbgs());
- }
- //===----------------------------------------------------------------------===//
- // UnloopUpdater implementation
- //
- namespace {
- /// Find the new parent loop for all blocks within the "unloop" whose last
- /// backedges has just been removed.
- class UnloopUpdater {
- Loop *Unloop;
- LoopInfo *LI;
- LoopBlocksDFS DFS;
- // Map unloop's immediate subloops to their nearest reachable parents. Nested
- // loops within these subloops will not change parents. However, an immediate
- // subloop's new parent will be the nearest loop reachable from either its own
- // exits *or* any of its nested loop's exits.
- DenseMap<Loop*, Loop*> SubloopParents;
- // Flag the presence of an irreducible backedge whose destination is a block
- // directly contained by the original unloop.
- bool FoundIB;
- public:
- UnloopUpdater(Loop *UL, LoopInfo *LInfo) :
- Unloop(UL), LI(LInfo), DFS(UL), FoundIB(false) {}
- void updateBlockParents();
- void removeBlocksFromAncestors();
- void updateSubloopParents();
- protected:
- Loop *getNearestLoop(BasicBlock *BB, Loop *BBLoop);
- };
- } // end anonymous namespace
- /// updateBlockParents - Update the parent loop for all blocks that are directly
- /// contained within the original "unloop".
- void UnloopUpdater::updateBlockParents() {
- if (Unloop->getNumBlocks()) {
- // Perform a post order CFG traversal of all blocks within this loop,
- // propagating the nearest loop from sucessors to predecessors.
- LoopBlocksTraversal Traversal(DFS, LI);
- for (LoopBlocksTraversal::POTIterator POI = Traversal.begin(),
- POE = Traversal.end(); POI != POE; ++POI) {
- Loop *L = LI->getLoopFor(*POI);
- Loop *NL = getNearestLoop(*POI, L);
- if (NL != L) {
- // For reducible loops, NL is now an ancestor of Unloop.
- assert((NL != Unloop && (!NL || NL->contains(Unloop))) &&
- "uninitialized successor");
- LI->changeLoopFor(*POI, NL);
- }
- else {
- // Or the current block is part of a subloop, in which case its parent
- // is unchanged.
- assert((FoundIB || Unloop->contains(L)) && "uninitialized successor");
- }
- }
- }
- // Each irreducible loop within the unloop induces a round of iteration using
- // the DFS result cached by Traversal.
- bool Changed = FoundIB;
- for (unsigned NIters = 0; Changed; ++NIters) {
- assert(NIters < Unloop->getNumBlocks() && "runaway iterative algorithm");
- // Iterate over the postorder list of blocks, propagating the nearest loop
- // from successors to predecessors as before.
- Changed = false;
- for (LoopBlocksDFS::POIterator POI = DFS.beginPostorder(),
- POE = DFS.endPostorder(); POI != POE; ++POI) {
- Loop *L = LI->getLoopFor(*POI);
- Loop *NL = getNearestLoop(*POI, L);
- if (NL != L) {
- assert(NL != Unloop && (!NL || NL->contains(Unloop)) &&
- "uninitialized successor");
- LI->changeLoopFor(*POI, NL);
- Changed = true;
- }
- }
- }
- }
- /// removeBlocksFromAncestors - Remove unloop's blocks from all ancestors below
- /// their new parents.
- void UnloopUpdater::removeBlocksFromAncestors() {
- // Remove unloop's blocks from all ancestors below their new parents.
- for (Loop::block_iterator BI = Unloop->block_begin(),
- BE = Unloop->block_end(); BI != BE; ++BI) {
- Loop *NewParent = LI->getLoopFor(*BI);
- // If this block is an immediate subloop, remove all blocks (including
- // nested subloops) from ancestors below the new parent loop.
- // Otherwise, if this block is in a nested subloop, skip it.
- if (SubloopParents.count(NewParent))
- NewParent = SubloopParents[NewParent];
- else if (Unloop->contains(NewParent))
- continue;
- // Remove blocks from former Ancestors except Unloop itself which will be
- // deleted.
- for (Loop *OldParent = Unloop->getParentLoop(); OldParent != NewParent;
- OldParent = OldParent->getParentLoop()) {
- assert(OldParent && "new loop is not an ancestor of the original");
- OldParent->removeBlockFromLoop(*BI);
- }
- }
- }
- /// updateSubloopParents - Update the parent loop for all subloops directly
- /// nested within unloop.
- void UnloopUpdater::updateSubloopParents() {
- while (!Unloop->empty()) {
- Loop *Subloop = *llvm::prior(Unloop->end());
- Unloop->removeChildLoop(llvm::prior(Unloop->end()));
- assert(SubloopParents.count(Subloop) && "DFS failed to visit subloop");
- if (SubloopParents[Subloop])
- SubloopParents[Subloop]->addChildLoop(Subloop);
- else
- LI->addTopLevelLoop(Subloop);
- }
- }
- /// getNearestLoop - Return the nearest parent loop among this block's
- /// successors. If a successor is a subloop header, consider its parent to be
- /// the nearest parent of the subloop's exits.
- ///
- /// For subloop blocks, simply update SubloopParents and return NULL.
- Loop *UnloopUpdater::getNearestLoop(BasicBlock *BB, Loop *BBLoop) {
- // Initially for blocks directly contained by Unloop, NearLoop == Unloop and
- // is considered uninitialized.
- Loop *NearLoop = BBLoop;
- Loop *Subloop = 0;
- if (NearLoop != Unloop && Unloop->contains(NearLoop)) {
- Subloop = NearLoop;
- // Find the subloop ancestor that is directly contained within Unloop.
- while (Subloop->getParentLoop() != Unloop) {
- Subloop = Subloop->getParentLoop();
- assert(Subloop && "subloop is not an ancestor of the original loop");
- }
- // Get the current nearest parent of the Subloop exits, initially Unloop.
- if (!SubloopParents.count(Subloop))
- SubloopParents[Subloop] = Unloop;
- NearLoop = SubloopParents[Subloop];
- }
- succ_iterator I = succ_begin(BB), E = succ_end(BB);
- if (I == E) {
- assert(!Subloop && "subloop blocks must have a successor");
- NearLoop = 0; // unloop blocks may now exit the function.
- }
- for (; I != E; ++I) {
- if (*I == BB)
- continue; // self loops are uninteresting
- Loop *L = LI->getLoopFor(*I);
- if (L == Unloop) {
- // This successor has not been processed. This path must lead to an
- // irreducible backedge.
- assert((FoundIB || !DFS.hasPostorder(*I)) && "should have seen IB");
- FoundIB = true;
- }
- if (L != Unloop && Unloop->contains(L)) {
- // Successor is in a subloop.
- if (Subloop)
- continue; // Branching within subloops. Ignore it.
- // BB branches from the original into a subloop header.
- assert(L->getParentLoop() == Unloop && "cannot skip into nested loops");
- // Get the current nearest parent of the Subloop's exits.
- L = SubloopParents[L];
- // L could be Unloop if the only exit was an irreducible backedge.
- }
- if (L == Unloop) {
- continue;
- }
- // Handle critical edges from Unloop into a sibling loop.
- if (L && !L->contains(Unloop)) {
- L = L->getParentLoop();
- }
- // Remember the nearest parent loop among successors or subloop exits.
- if (NearLoop == Unloop || !NearLoop || NearLoop->contains(L))
- NearLoop = L;
- }
- if (Subloop) {
- SubloopParents[Subloop] = NearLoop;
- return BBLoop;
- }
- return NearLoop;
- }
- //===----------------------------------------------------------------------===//
- // LoopInfo implementation
- //
- bool LoopInfo::runOnFunction(Function &) {
- releaseMemory();
- LI.Calculate(getAnalysis<DominatorTree>().getBase()); // Update
- return false;
- }
- /// updateUnloop - The last backedge has been removed from a loop--now the
- /// "unloop". Find a new parent for the blocks contained within unloop and
- /// update the loop tree. We don't necessarily have valid dominators at this
- /// point, but LoopInfo is still valid except for the removal of this loop.
- ///
- /// Note that Unloop may now be an empty loop. Calling Loop::getHeader without
- /// checking first is illegal.
- void LoopInfo::updateUnloop(Loop *Unloop) {
- // First handle the special case of no parent loop to simplify the algorithm.
- if (!Unloop->getParentLoop()) {
- // Since BBLoop had no parent, Unloop blocks are no longer in a loop.
- for (Loop::block_iterator I = Unloop->block_begin(),
- E = Unloop->block_end(); I != E; ++I) {
- // Don't reparent blocks in subloops.
- if (getLoopFor(*I) != Unloop)
- continue;
- // Blocks no longer have a parent but are still referenced by Unloop until
- // the Unloop object is deleted.
- LI.changeLoopFor(*I, 0);
- }
- // Remove the loop from the top-level LoopInfo object.
- for (LoopInfo::iterator I = LI.begin();; ++I) {
- assert(I != LI.end() && "Couldn't find loop");
- if (*I == Unloop) {
- LI.removeLoop(I);
- break;
- }
- }
- // Move all of the subloops to the top-level.
- while (!Unloop->empty())
- LI.addTopLevelLoop(Unloop->removeChildLoop(llvm::prior(Unloop->end())));
- return;
- }
- // Update the parent loop for all blocks within the loop. Blocks within
- // subloops will not change parents.
- UnloopUpdater Updater(Unloop, this);
- Updater.updateBlockParents();
- // Remove blocks from former ancestor loops.
- Updater.removeBlocksFromAncestors();
- // Add direct subloops as children in their new parent loop.
- Updater.updateSubloopParents();
- // Remove unloop from its parent loop.
- Loop *ParentLoop = Unloop->getParentLoop();
- for (Loop::iterator I = ParentLoop->begin();; ++I) {
- assert(I != ParentLoop->end() && "Couldn't find loop");
- if (*I == Unloop) {
- ParentLoop->removeChildLoop(I);
- break;
- }
- }
- }
- void LoopInfo::verifyAnalysis() const {
- // LoopInfo is a FunctionPass, but verifying every loop in the function
- // each time verifyAnalysis is called is very expensive. The
- // -verify-loop-info option can enable this. In order to perform some
- // checking by default, LoopPass has been taught to call verifyLoop
- // manually during loop pass sequences.
- if (!VerifyLoopInfo) return;
- DenseSet<const Loop*> Loops;
- for (iterator I = begin(), E = end(); I != E; ++I) {
- assert(!(*I)->getParentLoop() && "Top-level loop has a parent!");
- (*I)->verifyLoopNest(&Loops);
- }
- // Verify that blocks are mapped to valid loops.
- //
- // FIXME: With an up-to-date DFS (see LoopIterator.h) and DominatorTree, we
- // could also verify that the blocks are still in the correct loops.
- for (DenseMap<BasicBlock*, Loop*>::const_iterator I = LI.BBMap.begin(),
- E = LI.BBMap.end(); I != E; ++I) {
- assert(Loops.count(I->second) && "orphaned loop");
- assert(I->second->contains(I->first) && "orphaned block");
- }
- }
- void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AU.addRequired<DominatorTree>();
- }
- void LoopInfo::print(raw_ostream &OS, const Module*) const {
- LI.print(OS);
- }
- //===----------------------------------------------------------------------===//
- // LoopBlocksDFS implementation
- //
- /// Traverse the loop blocks and store the DFS result.
- /// Useful for clients that just want the final DFS result and don't need to
- /// visit blocks during the initial traversal.
- void LoopBlocksDFS::perform(LoopInfo *LI) {
- LoopBlocksTraversal Traversal(*this, LI);
- for (LoopBlocksTraversal::POTIterator POI = Traversal.begin(),
- POE = Traversal.end(); POI != POE; ++POI) ;
- }