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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/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/ScopeExit.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Analysis/LoopInfoImpl.h"
+#include "llvm/Analysis/LoopIterator.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Config/llvm-config.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugLoc.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+using namespace llvm;
+
+// Explicitly instantiate methods in LoopInfoImpl.h for IR-level Loops.
+template class llvm::LoopBase<BasicBlock, Loop>;
+template class llvm::LoopInfoBase<BasicBlock, Loop>;
+
+// Always verify loopinfo if expensive checking is enabled.
+#ifdef EXPENSIVE_CHECKS
+bool llvm::VerifyLoopInfo = true;
+#else
+bool llvm::VerifyLoopInfo = false;
+#endif
+static cl::opt<bool, true>
+ VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo),
+ cl::Hidden, cl::desc("Verify loop info (time consuming)"));
+
+//===----------------------------------------------------------------------===//
+// Loop implementation
+//
+
+bool Loop::isLoopInvariant(const Value *V) const {
+ if (const Instruction *I = dyn_cast<Instruction>(V))
+ return !contains(I);
+ return true; // All non-instructions are loop invariant
+}
+
+bool Loop::hasLoopInvariantOperands(const Instruction *I) const {
+ return all_of(I->operands(), [this](Value *V) { return isLoopInvariant(V); });
+}
+
+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.
+}
+
+bool Loop::makeLoopInvariant(Instruction *I, bool &Changed,
+ Instruction *InsertPt) const {
+ // Test if the value is already loop-invariant.
+ if (isLoopInvariant(I))
+ return true;
+ if (!isSafeToSpeculativelyExecute(I))
+ return false;
+ if (I->mayReadFromMemory())
+ return false;
+ // EH block instructions are immobile.
+ if (I->isEHPad())
+ 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 (Value *Operand : I->operands())
+ if (!makeLoopInvariant(Operand, Changed, InsertPt))
+ return false;
+
+ // Hoist.
+ I->moveBefore(InsertPt);
+
+ // There is possibility of hoisting this instruction above some arbitrary
+ // condition. Any metadata defined on it can be control dependent on this
+ // condition. Conservatively strip it here so that we don't give any wrong
+ // information to the optimizer.
+ I->dropUnknownNonDebugMetadata();
+
+ Changed = true;
+ return true;
+}
+
+PHINode *Loop::getCanonicalInductionVariable() const {
+ BasicBlock *H = getHeader();
+
+ BasicBlock *Incoming = nullptr, *Backedge = nullptr;
+ 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 nullptr; // dead loop
+ Incoming = *PI++;
+ if (PI != pred_end(H))
+ return nullptr; // multiple backedges?
+
+ if (contains(Incoming)) {
+ if (contains(Backedge))
+ return nullptr;
+ std::swap(Incoming, Backedge);
+ } else if (!contains(Backedge))
+ return nullptr;
+
+ // 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->isZero())
+ 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->isOne())
+ return PN;
+ }
+ return nullptr;
+}
+
+// Check that 'BB' doesn't have any uses outside of the 'L'
+static bool isBlockInLCSSAForm(const Loop &L, const BasicBlock &BB,
+ DominatorTree &DT) {
+ for (const Instruction &I : BB) {
+ // Tokens can't be used in PHI nodes and live-out tokens prevent loop
+ // optimizations, so for the purposes of considered LCSSA form, we
+ // can ignore them.
+ if (I.getType()->isTokenTy())
+ continue;
+
+ for (const Use &U : I.uses()) {
+ const Instruction *UI = cast<Instruction>(U.getUser());
+ const BasicBlock *UserBB = UI->getParent();
+ if (const PHINode *P = dyn_cast<PHINode>(UI))
+ UserBB = P->getIncomingBlock(U);
+
+ // 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 && !L.contains(UserBB) &&
+ DT.isReachableFromEntry(UserBB))
+ return false;
+ }
+ }
+ return true;
+}
+
+bool Loop::isLCSSAForm(DominatorTree &DT) const {
+ // For each block we check that it doesn't have any uses outside of this loop.
+ return all_of(this->blocks(), [&](const BasicBlock *BB) {
+ return isBlockInLCSSAForm(*this, *BB, DT);
+ });
+}
+
+bool Loop::isRecursivelyLCSSAForm(DominatorTree &DT, const LoopInfo &LI) const {
+ // For each block we check that it doesn't have any uses outside of its
+ // innermost loop. This process will transitively guarantee that the current
+ // loop and all of the nested loops are in LCSSA form.
+ return all_of(this->blocks(), [&](const BasicBlock *BB) {
+ return isBlockInLCSSAForm(*LI.getLoopFor(BB), *BB, DT);
+ });
+}
+
+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();
+}
+
+// Routines that reform the loop CFG and split edges often fail on indirectbr.
+bool Loop::isSafeToClone() const {
+ // Return false if any loop blocks contain indirectbrs, or there are any calls
+ // to noduplicate functions.
+ for (BasicBlock *BB : this->blocks()) {
+ if (isa<IndirectBrInst>(BB->getTerminator()))
+ return false;
+
+ for (Instruction &I : *BB)
+ if (auto CS = CallSite(&I))
+ if (CS.cannotDuplicate())
+ return false;
+ }
+ return true;
+}
+
+MDNode *Loop::getLoopID() const {
+ MDNode *LoopID = nullptr;
+ if (BasicBlock *Latch = getLoopLatch()) {
+ LoopID = Latch->getTerminator()->getMetadata(LLVMContext::MD_loop);
+ } else {
+ assert(!getLoopLatch() &&
+ "The loop should have no single latch at this point");
+ // Go through each predecessor of the loop header and check the
+ // terminator for the metadata.
+ BasicBlock *H = getHeader();
+ for (BasicBlock *BB : this->blocks()) {
+ TerminatorInst *TI = BB->getTerminator();
+ MDNode *MD = nullptr;
+
+ // Check if this terminator branches to the loop header.
+ for (BasicBlock *Successor : TI->successors()) {
+ if (Successor == H) {
+ MD = TI->getMetadata(LLVMContext::MD_loop);
+ break;
+ }
+ }
+ if (!MD)
+ return nullptr;
+
+ if (!LoopID)
+ LoopID = MD;
+ else if (MD != LoopID)
+ return nullptr;
+ }
+ }
+ if (!LoopID || LoopID->getNumOperands() == 0 ||
+ LoopID->getOperand(0) != LoopID)
+ return nullptr;
+ return LoopID;
+}
+
+void Loop::setLoopID(MDNode *LoopID) const {
+ assert(LoopID && "Loop ID should not be null");
+ assert(LoopID->getNumOperands() > 0 && "Loop ID needs at least one operand");
+ assert(LoopID->getOperand(0) == LoopID && "Loop ID should refer to itself");
+
+ if (BasicBlock *Latch = getLoopLatch()) {
+ Latch->getTerminator()->setMetadata(LLVMContext::MD_loop, LoopID);
+ return;
+ }
+
+ assert(!getLoopLatch() &&
+ "The loop should have no single latch at this point");
+ BasicBlock *H = getHeader();
+ for (BasicBlock *BB : this->blocks()) {
+ TerminatorInst *TI = BB->getTerminator();
+ for (BasicBlock *Successor : TI->successors()) {
+ if (Successor == H)
+ TI->setMetadata(LLVMContext::MD_loop, LoopID);
+ }
+ }
+}
+
+void Loop::setLoopAlreadyUnrolled() {
+ MDNode *LoopID = getLoopID();
+ // First remove any existing loop unrolling metadata.
+ SmallVector<Metadata *, 4> MDs;
+ // Reserve first location for self reference to the LoopID metadata node.
+ MDs.push_back(nullptr);
+
+ if (LoopID) {
+ for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
+ bool IsUnrollMetadata = false;
+ MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
+ if (MD) {
+ const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
+ IsUnrollMetadata = S && S->getString().startswith("llvm.loop.unroll.");
+ }
+ if (!IsUnrollMetadata)
+ MDs.push_back(LoopID->getOperand(i));
+ }
+ }
+
+ // Add unroll(disable) metadata to disable future unrolling.
+ LLVMContext &Context = getHeader()->getContext();
+ SmallVector<Metadata *, 1> DisableOperands;
+ DisableOperands.push_back(MDString::get(Context, "llvm.loop.unroll.disable"));
+ MDNode *DisableNode = MDNode::get(Context, DisableOperands);
+ MDs.push_back(DisableNode);
+
+ MDNode *NewLoopID = MDNode::get(Context, MDs);
+ // Set operand 0 to refer to the loop id itself.
+ NewLoopID->replaceOperandWith(0, NewLoopID);
+ setLoopID(NewLoopID);
+}
+
+bool Loop::isAnnotatedParallel() const {
+ MDNode *DesiredLoopIdMetadata = getLoopID();
+
+ if (!DesiredLoopIdMetadata)
+ return false;
+
+ // The loop branch contains the parallel loop metadata. In order to ensure
+ // that any parallel-loop-unaware optimization pass hasn't added loop-carried
+ // dependencies (thus converted the loop back to a sequential loop), check
+ // that all the memory instructions in the loop contain parallelism metadata
+ // that point to the same unique "loop id metadata" the loop branch does.
+ for (BasicBlock *BB : this->blocks()) {
+ for (Instruction &I : *BB) {
+ if (!I.mayReadOrWriteMemory())
+ continue;
+
+ // The memory instruction can refer to the loop identifier metadata
+ // directly or indirectly through another list metadata (in case of
+ // nested parallel loops). The loop identifier metadata refers to
+ // itself so we can check both cases with the same routine.
+ MDNode *LoopIdMD =
+ I.getMetadata(LLVMContext::MD_mem_parallel_loop_access);
+
+ if (!LoopIdMD)
+ return false;
+
+ bool LoopIdMDFound = false;
+ for (const MDOperand &MDOp : LoopIdMD->operands()) {
+ if (MDOp == DesiredLoopIdMetadata) {
+ LoopIdMDFound = true;
+ break;
+ }
+ }
+
+ if (!LoopIdMDFound)
+ return false;
+ }
+ }
+ return true;
+}
+
+DebugLoc Loop::getStartLoc() const { return getLocRange().getStart(); }
+
+Loop::LocRange Loop::getLocRange() const {
+ // If we have a debug location in the loop ID, then use it.
+ if (MDNode *LoopID = getLoopID()) {
+ DebugLoc Start;
+ // We use the first DebugLoc in the header as the start location of the loop
+ // and if there is a second DebugLoc in the header we use it as end location
+ // of the loop.
+ for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
+ if (DILocation *L = dyn_cast<DILocation>(LoopID->getOperand(i))) {
+ if (!Start)
+ Start = DebugLoc(L);
+ else
+ return LocRange(Start, DebugLoc(L));
+ }
+ }
+
+ if (Start)
+ return LocRange(Start);
+ }
+
+ // Try the pre-header first.
+ if (BasicBlock *PHeadBB = getLoopPreheader())
+ if (DebugLoc DL = PHeadBB->getTerminator()->getDebugLoc())
+ return LocRange(DL);
+
+ // If we have no pre-header or there are no instructions with debug
+ // info in it, try the header.
+ if (BasicBlock *HeadBB = getHeader())
+ return LocRange(HeadBB->getTerminator()->getDebugLoc());
+
+ return LocRange();
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void Loop::dump() const { print(dbgs()); }
+
+LLVM_DUMP_METHOD void Loop::dumpVerbose() const {
+ print(dbgs(), /*Depth=*/0, /*Verbose=*/true);
+}
+#endif
+
+//===----------------------------------------------------------------------===//
+// 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
+
+/// 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 successors to predecessors.
+ LoopBlocksTraversal Traversal(DFS, LI);
+ for (BasicBlock *POI : Traversal) {
+
+ 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;
+ }
+ }
+ }
+}
+
+/// Remove unloop's blocks from all ancestors below their new parents.
+void UnloopUpdater::removeBlocksFromAncestors() {
+ // Remove all unloop's blocks (including those in nested subloops) from
+ // ancestors below the new parent loop.
+ for (Loop::block_iterator BI = Unloop.block_begin(), BE = Unloop.block_end();
+ BI != BE; ++BI) {
+ Loop *OuterParent = LI->getLoopFor(*BI);
+ if (Unloop.contains(OuterParent)) {
+ while (OuterParent->getParentLoop() != &Unloop)
+ OuterParent = OuterParent->getParentLoop();
+ OuterParent = SubloopParents[OuterParent];
+ }
+ // Remove blocks from former Ancestors except Unloop itself which will be
+ // deleted.
+ for (Loop *OldParent = Unloop.getParentLoop(); OldParent != OuterParent;
+ OldParent = OldParent->getParentLoop()) {
+ assert(OldParent && "new loop is not an ancestor of the original");
+ OldParent->removeBlockFromLoop(*BI);
+ }
+ }
+}
+
+/// Update the parent loop for all subloops directly nested within unloop.
+void UnloopUpdater::updateSubloopParents() {
+ while (!Unloop.empty()) {
+ Loop *Subloop = *std::prev(Unloop.end());
+ Unloop.removeChildLoop(std::prev(Unloop.end()));
+
+ assert(SubloopParents.count(Subloop) && "DFS failed to visit subloop");
+ if (Loop *Parent = SubloopParents[Subloop])
+ Parent->addChildLoop(Subloop);
+ else
+ LI->addTopLevelLoop(Subloop);
+ }
+}
+
+/// 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 = nullptr;
+ 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.
+ NearLoop = SubloopParents.insert({Subloop, &Unloop}).first->second;
+ }
+
+ succ_iterator I = succ_begin(BB), E = succ_end(BB);
+ if (I == E) {
+ assert(!Subloop && "subloop blocks must have a successor");
+ NearLoop = nullptr; // 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::LoopInfo(const DomTreeBase<BasicBlock> &DomTree) { analyze(DomTree); }
+
+bool LoopInfo::invalidate(Function &F, const PreservedAnalyses &PA,
+ FunctionAnalysisManager::Invalidator &) {
+ // Check whether the analysis, all analyses on functions, or the function's
+ // CFG have been preserved.
+ auto PAC = PA.getChecker<LoopAnalysis>();
+ return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
+ PAC.preservedSet<CFGAnalyses>());
+}
+
+void LoopInfo::erase(Loop *Unloop) {
+ assert(!Unloop->isInvalid() && "Loop has already been erased!");
+
+ auto InvalidateOnExit = make_scope_exit([&]() { destroy(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.
+ changeLoopFor(*I, nullptr);
+ }
+
+ // Remove the loop from the top-level LoopInfo object.
+ for (iterator I = begin();; ++I) {
+ assert(I != end() && "Couldn't find loop");
+ if (*I == Unloop) {
+ removeLoop(I);
+ break;
+ }
+ }
+
+ // Move all of the subloops to the top-level.
+ while (!Unloop->empty())
+ addTopLevelLoop(Unloop->removeChildLoop(std::prev(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;
+ }
+ }
+}
+
+AnalysisKey LoopAnalysis::Key;
+
+LoopInfo LoopAnalysis::run(Function &F, FunctionAnalysisManager &AM) {
+ // FIXME: Currently we create a LoopInfo from scratch for every function.
+ // This may prove to be too wasteful due to deallocating and re-allocating
+ // memory each time for the underlying map and vector datastructures. At some
+ // point it may prove worthwhile to use a freelist and recycle LoopInfo
+ // objects. I don't want to add that kind of complexity until the scope of
+ // the problem is better understood.
+ LoopInfo LI;
+ LI.analyze(AM.getResult<DominatorTreeAnalysis>(F));
+ return LI;
+}
+
+PreservedAnalyses LoopPrinterPass::run(Function &F,
+ FunctionAnalysisManager &AM) {
+ AM.getResult<LoopAnalysis>(F).print(OS);
+ return PreservedAnalyses::all();
+}
+
+void llvm::printLoop(Loop &L, raw_ostream &OS, const std::string &Banner) {
+
+ if (forcePrintModuleIR()) {
+ // handling -print-module-scope
+ OS << Banner << " (loop: ";
+ L.getHeader()->printAsOperand(OS, false);
+ OS << ")\n";
+
+ // printing whole module
+ OS << *L.getHeader()->getModule();
+ return;
+ }
+
+ OS << Banner;
+
+ auto *PreHeader = L.getLoopPreheader();
+ if (PreHeader) {
+ OS << "\n; Preheader:";
+ PreHeader->print(OS);
+ OS << "\n; Loop:";
+ }
+
+ for (auto *Block : L.blocks())
+ if (Block)
+ Block->print(OS);
+ else
+ OS << "Printing <null> block";
+
+ SmallVector<BasicBlock *, 8> ExitBlocks;
+ L.getExitBlocks(ExitBlocks);
+ if (!ExitBlocks.empty()) {
+ OS << "\n; Exit blocks";
+ for (auto *Block : ExitBlocks)
+ if (Block)
+ Block->print(OS);
+ else
+ OS << "Printing <null> block";
+ }
+}
+
+//===----------------------------------------------------------------------===//
+// LoopInfo implementation
+//
+
+char LoopInfoWrapperPass::ID = 0;
+INITIALIZE_PASS_BEGIN(LoopInfoWrapperPass, "loops", "Natural Loop Information",
+ true, true)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(LoopInfoWrapperPass, "loops", "Natural Loop Information",
+ true, true)
+
+bool LoopInfoWrapperPass::runOnFunction(Function &) {
+ releaseMemory();
+ LI.analyze(getAnalysis<DominatorTreeWrapperPass>().getDomTree());
+ return false;
+}
+
+void LoopInfoWrapperPass::verifyAnalysis() const {
+ // LoopInfoWrapperPass 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) {
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ LI.verify(DT);
+ }
+}
+
+void LoopInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ AU.addRequired<DominatorTreeWrapperPass>();
+}
+
+void LoopInfoWrapperPass::print(raw_ostream &OS, const Module *) const {
+ LI.print(OS);
+}
+
+PreservedAnalyses LoopVerifierPass::run(Function &F,
+ FunctionAnalysisManager &AM) {
+ LoopInfo &LI = AM.getResult<LoopAnalysis>(F);
+ auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+ LI.verify(DT);
+ return PreservedAnalyses::all();
+}
+
+//===----------------------------------------------------------------------===//
+// 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)
+ ;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-03-04 04:58:49 +0000