//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
-//
+//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
//===----------------------------------------------------------------------===//
//
// This file defines the LoopInfo class that is used to identify natural loops
-// and determine the loop depth of various nodes of the CFG. Note that natural
+// 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
// each natural loop identified, this analysis identifies natural loops
-// contained entirely within the function, the basic blocks the make up the
-// loop, the nesting depth of the loop, and the successor blocks of the loop.
+// contained entirely within the loop and the basic blocks the make up the loop.
+//
+// It can calculate on the fly various bits of information, for example:
//
-// It can calculate on the fly a variety of different bits of information, such
-// as whether there is a preheader for the loop, the number of back edges to the
-// header, and whether or not a particular block branches out of the loop.
+// * whether there is a preheader for the loop
+// * the number of back edges to the header
+// * whether or not a particular block branches out of the loop
+// * the successor blocks of the loop
+// * the loop depth
+// * etc...
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ANALYSIS_LOOP_INFO_H
-#define LLVM_ANALYSIS_LOOP_INFO_H
-
+#ifndef LLVM_ANALYSIS_LOOPINFO_H
+#define LLVM_ANALYSIS_LOOPINFO_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
#include "llvm/Pass.h"
-#include "Support/GraphTraits.h"
-#include <set>
+#include <algorithm>
namespace llvm {
-class DominatorSet;
+// FIXME: Replace this brittle forward declaration with the include of the new
+// PassManager.h when doing so doesn't break the PassManagerBuilder.
+template <typename IRUnitT> class AnalysisManager;
+class PreservedAnalyses;
+
+class DominatorTree;
class LoopInfo;
+class Loop;
+class MDNode;
class PHINode;
-class Instruction;
+class raw_ostream;
+template<class N> class DominatorTreeBase;
+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
- unsigned LoopDepth; // Nesting depth of this loop
-
- Loop(const Loop &); // DO NOT IMPLEMENT
- const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
+template<class BlockT, class 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;
+
+ SmallPtrSet<const BlockT*, 8> DenseBlockSet;
+
+ /// Indicator that this loop is no longer a valid loop.
+ bool IsInvalid = false;
+
+ LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
+ const LoopBase<BlockT, LoopT>&
+ operator=(const LoopBase<BlockT, LoopT> &) = delete;
public:
/// Loop ctor - This creates an empty loop.
- Loop() : ParentLoop(0), LoopDepth(0) {
- }
- ~Loop() {
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
+ LoopBase() : ParentLoop(nullptr) {}
+ ~LoopBase() {
+ for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
delete SubLoops[i];
}
- unsigned getLoopDepth() const { return LoopDepth; }
- BasicBlock *getHeader() const { return Blocks.front(); }
- Loop *getParentLoop() const { return ParentLoop; }
+ /// 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 = 1;
+ for (const LoopT *CurLoop = ParentLoop; CurLoop;
+ CurLoop = CurLoop->ParentLoop)
+ ++D;
+ return D;
+ }
+ BlockT *getHeader() const { return Blocks.front(); }
+ LoopT *getParentLoop() const { return ParentLoop; }
- /// contains - Return true of 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) 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 DenseBlockSet.count(BB);
+ }
+
+ /// contains - Return true if the specified instruction is in this loop.
///
- bool contains(const BasicBlock *BB) const;
+ template<class InstT>
+ bool contains(const InstT *Inst) const {
+ return contains(Inst->getParent());
+ }
/// iterator/begin/end - Return the loops contained entirely within this loop.
///
- typedef std::vector<Loop*>::const_iterator iterator;
+ 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<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(); }
+ inline iterator_range<block_iterator> blocks() const {
+ return make_range(block_begin(), block_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;
+ /// getNumBlocks - Get the number of blocks in this loop in constant time.
+ unsigned getNumBlocks() const {
+ return Blocks.size();
+ }
- /// getNumBackEdges - Calculate the number of back edges to the loop header
+ /// Invalidate the loop, indicating that it is no longer a loop.
+ void invalidate() { IsInvalid = true; }
+
+ /// Return true if this loop is no longer valid.
+ bool isInvalid() { return IsInvalid; }
+
+ /// isLoopExiting - True if terminator in the block can branch to another
+ /// block that is outside of the current loop.
///
- unsigned getNumBackEdges() const;
+ bool isLoopExiting(const BlockT *BB) const {
+ typedef GraphTraits<const BlockT*> BlockTraits;
+ for (typename BlockTraits::ChildIteratorType SI =
+ BlockTraits::child_begin(BB),
+ SE = BlockTraits::child_end(BB); SI != SE; ++SI) {
+ if (!contains(*SI))
+ return true;
+ }
+ return false;
+ }
- /// isLoopInvariant - Return true if the specified value is loop invariant
+ /// getNumBackEdges - Calculate the number of back edges to the loop header
///
- 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(H),
+ E = InvBlockTraits::child_end(H); I != E; ++I)
+ if (contains(*I))
+ ++NumBackEdges;
+
+ return NumBackEdges;
+ }
//===--------------------------------------------------------------------===//
// APIs for simple analysis of the loop.
// induction variable canonicalization pass should be used to normalize loops
// for easy analysis. These methods assume canonical loops.
+ /// getExitingBlocks - Return all blocks inside the loop that have successors
+ /// outside of the loop. These are the blocks _inside of the current loop_
+ /// which branch out. The returned list is always unique.
+ ///
+ void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
+
+ /// getExitingBlock - If getExitingBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ 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(std::vector<BasicBlock*> &Blocks) const;
+ void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
+
+ /// getExitBlock - If getExitBlocks would return exactly one block,
+ /// return that block. Otherwise return null.
+ BlockT *getExitBlock() const;
+
+ /// Edge type.
+ typedef std::pair<const BlockT*, const BlockT*> Edge;
+
+ /// 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.
///
- BasicBlock *getLoopPreheader() 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;
-
- /// 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;
+ BlockT *getLoopPreheader() 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.
+ /// 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.
///
- Value *getTripCount() const;
+ 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.
+ BlockT *getLoopLatch() const;
+
+ /// getLoopLatches - Return all loop latch blocks of this loop. A latch block
+ /// is a block that contains a branch back to the header.
+ void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
+ BlockT *H = getHeader();
+ typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+ for (typename InvBlockTraits::ChildIteratorType I =
+ InvBlockTraits::child_begin(H),
+ E = InvBlockTraits::child_end(H); I != E; ++I)
+ if (contains(*I))
+ LoopLatches.push_back(*I);
+ }
//===--------------------------------------------------------------------===//
// 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);
/// 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 && "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 = nullptr;
+ 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);
+ DenseBlockSet.insert(BB);
+ }
+
+ /// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop
+ void reverseBlock(unsigned from) {
+ std::reverse(Blocks.begin() + from, Blocks.end());
+ }
+
+ /// reserveBlocks- interface to do reserve() for Blocks
+ void reserveBlocks(unsigned size) {
+ Blocks.reserve(size);
+ }
+
+ /// moveToHeader - This method is used to move BB (which must be part of this
+ /// loop) to be the loop header of the loop (the block that dominates all
+ /// others).
+ void moveToHeader(BlockT *BB) {
+ if (Blocks[0] == BB) return;
+ for (unsigned i = 0; ; ++i) {
+ assert(i != Blocks.size() && "Loop does not contain BB!");
+ if (Blocks[i] == BB) {
+ Blocks[i] = Blocks[0];
+ Blocks[0] = BB;
+ return;
+ }
+ }
}
/// removeBlockFromLoop - This removes the specified basic block from the
/// current loop, updating the Blocks as appropriate. This does not update
/// the mapping in the LoopInfo class.
- void removeBlockFromLoop(BasicBlock *BB);
+ void removeBlockFromLoop(BlockT *BB) {
+ auto I = std::find(Blocks.begin(), Blocks.end(), BB);
+ assert(I != Blocks.end() && "N is not in this list!");
+ Blocks.erase(I);
- void print(std::ostream &O, unsigned Depth = 0) const;
- void dump() const;
-private:
- friend class LoopInfo;
- Loop(BasicBlock *BB) : ParentLoop(0) {
- Blocks.push_back(BB); LoopDepth = 0;
+ DenseBlockSet.erase(BB);
}
- void setLoopDepth(unsigned Level) {
- LoopDepth = Level;
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- SubLoops[i]->setLoopDepth(Level+1);
+
+ /// verifyLoop - Verify loop structure
+ void verifyLoop() const;
+
+ /// verifyLoop - Verify loop structure of this loop and all nested loops.
+ void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
+
+ void print(raw_ostream &OS, unsigned Depth = 0) const;
+
+protected:
+ friend class LoopInfoBase<BlockT, LoopT>;
+ explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
+ Blocks.push_back(BB);
+ DenseBlockSet.insert(BB);
}
};
+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
+extern template class LoopBase<BasicBlock, Loop>;
+
+class Loop : public LoopBase<BasicBlock, Loop> {
+public:
+ Loop() {}
+
+ /// isLoopInvariant - Return true if the specified value is loop invariant
+ ///
+ bool isLoopInvariant(const Value *V) const;
+
+ /// hasLoopInvariantOperands - Return true if all the operands of the
+ /// specified instruction are loop invariant.
+ bool hasLoopInvariantOperands(const 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 = nullptr) 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 = nullptr) 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;
+
+ /// isLCSSAForm - Return true if the Loop is in LCSSA form
+ bool isLCSSAForm(DominatorTree &DT) const;
+
+ /// \brief Return true if this Loop and all inner subloops are in LCSSA form.
+ bool isRecursivelyLCSSAForm(DominatorTree &DT) const;
+
+ /// 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;
+
+ /// Returns true if the loop is annotated parallel.
+ ///
+ /// A parallel loop can be assumed to not contain any dependencies between
+ /// iterations by the compiler. That is, any loop-carried dependency checking
+ /// can be skipped completely when parallelizing the loop on the target
+ /// machine. Thus, if the parallel loop information originates from the
+ /// programmer, e.g. via the OpenMP parallel for pragma, it is the
+ /// programmer's responsibility to ensure there are no loop-carried
+ /// dependencies. The final execution order of the instructions across
+ /// iterations is not guaranteed, thus, the end result might or might not
+ /// implement actual concurrent execution of instructions across multiple
+ /// iterations.
+ bool isAnnotatedParallel() const;
+
+ /// Return the llvm.loop loop id metadata node for this loop if it is present.
+ ///
+ /// If this loop contains the same llvm.loop metadata on each branch to the
+ /// header then the node is returned. If any latch instruction does not
+ /// contain llvm.loop or or if multiple latches contain different nodes then
+ /// 0 is returned.
+ MDNode *getLoopID() const;
+ /// Set the llvm.loop loop id metadata for this loop.
+ ///
+ /// The LoopID metadata node will be added to each terminator instruction in
+ /// the loop that branches to the loop header.
+ ///
+ /// The LoopID metadata node should have one or more operands and the first
+ /// operand should should be the node itself.
+ void setLoopID(MDNode *LoopID) 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.
+ ///
+ void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
+
+ /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
+ /// block, return that block. Otherwise return null.
+ BasicBlock *getUniqueExitBlock() const;
+
+ void dump() const;
+
+ /// \brief Return the debug location of the start of this loop.
+ /// This looks for a BB terminating instruction with a known debug
+ /// location by looking at the preheader and header blocks. If it
+ /// cannot find a terminating instruction with location information,
+ /// it returns an unknown location.
+ DebugLoc getStartLoc() const {
+ BasicBlock *HeadBB;
+
+ // Try the pre-header first.
+ if ((HeadBB = getLoopPreheader()) != nullptr)
+ if (DebugLoc DL = HeadBB->getTerminator()->getDebugLoc())
+ return DL;
+
+ // If we have no pre-header or there are no instructions with debug
+ // info in it, try the header.
+ HeadBB = getHeader();
+ if (HeadBB)
+ return HeadBB->getTerminator()->getDebugLoc();
+
+ return DebugLoc();
+ }
+
+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;
+ DenseMap<const BlockT *, LoopT *> BBMap;
+ std::vector<LoopT *> TopLevelLoops;
+ std::vector<LoopT *> RemovedLoops;
+
+ friend class LoopBase<BlockT, LoopT>;
+ friend class LoopInfo;
+
+ void operator=(const LoopInfoBase &) = delete;
+ LoopInfoBase(const LoopInfoBase &) = delete;
public:
- ~LoopInfo() { releaseMemory(); }
+ LoopInfoBase() { }
+ ~LoopInfoBase() { releaseMemory(); }
+
+ LoopInfoBase(LoopInfoBase &&Arg)
+ : BBMap(std::move(Arg.BBMap)),
+ TopLevelLoops(std::move(Arg.TopLevelLoops)) {
+ // We have to clear the arguments top level loops as we've taken ownership.
+ Arg.TopLevelLoops.clear();
+ }
+ LoopInfoBase &operator=(LoopInfoBase &&RHS) {
+ BBMap = std::move(RHS.BBMap);
+
+ for (auto *L : TopLevelLoops)
+ delete L;
+ TopLevelLoops = std::move(RHS.TopLevelLoops);
+ RHS.TopLevelLoops.clear();
+ return *this;
+ }
+
+ void releaseMemory() {
+ BBMap.clear();
+
+ for (auto *L : TopLevelLoops)
+ delete L;
+ TopLevelLoops.clear();
+ for (auto *L : RemovedLoops)
+ delete L;
+ RemovedLoops.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;
+ 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.
///
- const Loop *getLoopFor(const BasicBlock *BB) const {
- std::map<BasicBlock *, Loop*>::const_iterator I=BBMap.find((BasicBlock*)BB);
- return I != BBMap.end() ? I->second : 0;
- }
+ LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
/// operator[] - same as getLoopFor...
///
- inline 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 {
- return getLoopFor(BB)->getHeader() == BB;
+ bool isLoopHeader(const BlockT *BB) const {
+ const LoopT *L = getLoopFor(BB);
+ return L && L->getHeader() == BB;
}
- /// runOnFunction - Calculate the natural loop information.
- ///
- virtual bool runOnFunction(Function &F);
-
- virtual void releaseMemory();
- void print(std::ostream &O) const;
-
- /// getAnalysisUsage - Requires dominator sets
- ///
- 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);
+ LoopT *removeLoop(iterator I) {
+ assert(I != end() && "Cannot remove end iterator!");
+ LoopT *L = *I;
+ assert(!L->getParentLoop() && "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(BasicBlock *BB, Loop *L);
+ void changeLoopFor(BlockT *BB, LoopT *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(Loop *OldLoop, Loop *NewLoop);
+ void changeTopLevelLoop(LoopT *OldLoop,
+ LoopT *NewLoop) {
+ auto I = std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
+ assert(I != TopLevelLoops.end() && "Old loop not at top level!");
+ *I = NewLoop;
+ assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
+ "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() && "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(BasicBlock *BB);
+ void removeBlock(BlockT *BB) {
+ auto I = BBMap.find(BB);
+ if (I != BBMap.end()) {
+ for (LoopT *L = I->second; L; L = L->getParentLoop())
+ L->removeBlockFromLoop(BB);
+
+ BBMap.erase(I);
+ }
+ }
- static void stub(); // Noop
-private:
- void Calculate(const DominatorSet &DS);
- Loop *ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS);
- void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent);
- void InsertLoopInto(Loop *L, Loop *Parent);
+ // Internals
+
+ static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
+ const LoopT *ParentLoop) {
+ if (!SubLoop) return true;
+ if (SubLoop == ParentLoop) return false;
+ return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
+ }
+
+ /// Create the loop forest using a stable algorithm.
+ void analyze(const DominatorTreeBase<BlockT> &DomTree);
+
+ // Debugging
+ void print(raw_ostream &OS) const;
+
+ void verify() const;
};
+// Implementation in LoopInfoImpl.h
+extern template class LoopInfoBase<BasicBlock, Loop>;
+
+class LoopInfo : public LoopInfoBase<BasicBlock, Loop> {
+ typedef LoopInfoBase<BasicBlock, Loop> BaseT;
+
+ friend class LoopBase<BasicBlock, Loop>;
-// Make sure that any clients of this file link in LoopInfo.cpp
-static IncludeFile
-LOOP_INFO_INCLUDE_FILE((void*)&LoopInfo::stub);
+ void operator=(const LoopInfo &) = delete;
+ LoopInfo(const LoopInfo &) = delete;
+public:
+ LoopInfo() {}
+ explicit LoopInfo(const DominatorTreeBase<BasicBlock> &DomTree);
+
+ LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
+ LoopInfo &operator=(LoopInfo &&RHS) {
+ BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
+ return *this;
+ }
+
+ // Most of the public interface is provided via LoopInfoBase.
+
+ /// Update LoopInfo after removing the last backedge from a loop. This updates
+ /// the loop forest and parent loops for each block so that \c L is no longer
+ /// referenced, but does not actually delete \c L immediately. The pointer
+ /// will remain valid until this LoopInfo's memory is released.
+ void markAsRemoved(Loop *L);
+
+ /// 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()));
+ }
+
+ /// \brief Checks if moving a specific instruction can break LCSSA in any
+ /// loop.
+ ///
+ /// Return true if moving \p Inst to before \p NewLoc will break LCSSA,
+ /// assuming that the function containing \p Inst and \p NewLoc is currently
+ /// in LCSSA form.
+ bool movementPreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc) {
+ assert(Inst->getFunction() == NewLoc->getFunction() &&
+ "Can't reason about IPO!");
+
+ auto *OldBB = Inst->getParent();
+ auto *NewBB = NewLoc->getParent();
+
+ // Movement within the same loop does not break LCSSA (the equality check is
+ // to avoid doing a hashtable lookup in case of intra-block movement).
+ if (OldBB == NewBB)
+ return true;
+
+ auto *OldLoop = getLoopFor(OldBB);
+ auto *NewLoop = getLoopFor(NewBB);
+
+ if (OldLoop == NewLoop)
+ return true;
+
+ // Check if Outer contains Inner; with the null loop counting as the
+ // "outermost" loop.
+ auto Contains = [](const Loop *Outer, const Loop *Inner) {
+ return !Outer || Outer->contains(Inner);
+ };
+
+ // To check that the movement of Inst to before NewLoc does not break LCSSA,
+ // we need to check two sets of uses for possible LCSSA violations at
+ // NewLoc: the users of NewInst, and the operands of NewInst.
+
+ // If we know we're hoisting Inst out of an inner loop to an outer loop,
+ // then the uses *of* Inst don't need to be checked.
+
+ if (!Contains(NewLoop, OldLoop)) {
+ for (Use &U : Inst->uses()) {
+ auto *UI = cast<Instruction>(U.getUser());
+ auto *UBB = isa<PHINode>(UI) ? cast<PHINode>(UI)->getIncomingBlock(U)
+ : UI->getParent();
+ if (UBB != NewBB && getLoopFor(UBB) != NewLoop)
+ return false;
+ }
+ }
+
+ // If we know we're sinking Inst from an outer loop into an inner loop, then
+ // the *operands* of Inst don't need to be checked.
+
+ if (!Contains(OldLoop, NewLoop)) {
+ // See below on why we can't handle phi nodes here.
+ if (isa<PHINode>(Inst))
+ return false;
+
+ for (Use &U : Inst->operands()) {
+ auto *DefI = dyn_cast<Instruction>(U.get());
+ if (!DefI)
+ return false;
+
+ // This would need adjustment if we allow Inst to be a phi node -- the
+ // new use block won't simply be NewBB.
+
+ auto *DefBlock = DefI->getParent();
+ if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop)
+ return false;
+ }
+ }
+
+ return true;
+ }
+};
// 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) {
+ static inline ChildIteratorType child_begin(NodeType *N) {
return N->begin();
}
- static inline ChildIteratorType child_end(NodeType *N) {
+ static inline ChildIteratorType child_end(NodeType *N) {
return N->end();
}
};
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) {
+ static inline ChildIteratorType child_begin(NodeType *N) {
return N->begin();
}
- static inline ChildIteratorType child_end(NodeType *N) {
+ static inline ChildIteratorType child_end(NodeType *N) {
return N->end();
}
};
+/// \brief Analysis pass that exposes the \c LoopInfo for a function.
+class LoopAnalysis {
+ static char PassID;
+
+public:
+ typedef LoopInfo Result;
+
+ /// \brief Opaque, unique identifier for this analysis pass.
+ static void *ID() { return (void *)&PassID; }
+
+ /// \brief Provide a name for the analysis for debugging and logging.
+ static StringRef name() { return "LoopAnalysis"; }
+
+ LoopInfo run(Function &F, AnalysisManager<Function> *AM);
+};
+
+/// \brief Printer pass for the \c LoopAnalysis results.
+class LoopPrinterPass {
+ raw_ostream &OS;
+
+public:
+ explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
+ PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
+
+ static StringRef name() { return "LoopPrinterPass"; }
+};
+
+/// \brief The legacy pass manager's analysis pass to compute loop information.
+class LoopInfoWrapperPass : public FunctionPass {
+ LoopInfo LI;
+
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopInfoWrapperPass() : FunctionPass(ID) {
+ initializeLoopInfoWrapperPassPass(*PassRegistry::getPassRegistry());
+ }
+
+ LoopInfo &getLoopInfo() { return LI; }
+ const LoopInfo &getLoopInfo() const { return LI; }
+
+ /// \brief Calculate the natural loop information for a given function.
+ bool runOnFunction(Function &F) override;
+
+ void verifyAnalysis() const override;
+
+ void releaseMemory() override { LI.releaseMemory(); }
+
+ void print(raw_ostream &O, const Module *M = nullptr) const override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+};
+
+/// \brief Pass for printing a loop's contents as LLVM's text IR assembly.
+class PrintLoopPass {
+ raw_ostream &OS;
+ std::string Banner;
+
+public:
+ PrintLoopPass();
+ PrintLoopPass(raw_ostream &OS, const std::string &Banner = "");
+
+ PreservedAnalyses run(Loop &L);
+ static StringRef name() { return "PrintLoopPass"; }
+};
+
} // End llvm namespace
#endif
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