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769 lines
27 KiB
C++
769 lines
27 KiB
C++
//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the LoopInfo class that is used to identify natural loops
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// and determine the loop depth of various nodes of the CFG. A natural loop
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// has exactly one entry-point, which is called the header. Note that natural
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// loops may actually be several loops that share the same header node.
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//
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// This analysis calculates the nesting structure of loops in a function. For
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// each natural loop identified, this analysis identifies natural loops
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// contained entirely within the loop and the basic blocks the make up the loop.
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//
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// It can calculate on the fly various bits of information, for example:
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//
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// * whether there is a preheader for the loop
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// * the number of back edges to the header
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// * whether or not a particular block branches out of the loop
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// * the successor blocks of the loop
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// * the loop depth
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// * etc...
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LOOPINFO_H
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#define LLVM_ANALYSIS_LOOPINFO_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/Pass.h"
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#include <algorithm>
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namespace llvm {
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// FIXME: Replace this brittle forward declaration with the include of the new
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// PassManager.h when doing so doesn't break the PassManagerBuilder.
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template <typename IRUnitT> class AnalysisManager;
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class PreservedAnalyses;
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class DominatorTree;
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class LoopInfo;
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class Loop;
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class MDNode;
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class PHINode;
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class raw_ostream;
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template<class N> class DominatorTreeBase;
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template<class N, class M> class LoopInfoBase;
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template<class N, class M> class LoopBase;
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//===----------------------------------------------------------------------===//
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/// LoopBase class - Instances of this class are used to represent loops that
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/// are detected in the flow graph
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///
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template<class BlockT, class LoopT>
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class LoopBase {
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LoopT *ParentLoop;
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// SubLoops - Loops contained entirely within this one.
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std::vector<LoopT *> SubLoops;
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// Blocks - The list of blocks in this loop. First entry is the header node.
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std::vector<BlockT*> Blocks;
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SmallPtrSet<const BlockT*, 8> DenseBlockSet;
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LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
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const LoopBase<BlockT, LoopT>&
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operator=(const LoopBase<BlockT, LoopT> &) = delete;
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public:
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/// Loop ctor - This creates an empty loop.
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LoopBase() : ParentLoop(nullptr) {}
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~LoopBase() {
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for (size_t i = 0, e = SubLoops.size(); i != e; ++i)
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delete SubLoops[i];
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}
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/// getLoopDepth - Return the nesting level of this loop. An outer-most
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/// loop has depth 1, for consistency with loop depth values used for basic
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/// blocks, where depth 0 is used for blocks not inside any loops.
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unsigned getLoopDepth() const {
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unsigned D = 1;
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for (const LoopT *CurLoop = ParentLoop; CurLoop;
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CurLoop = CurLoop->ParentLoop)
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++D;
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return D;
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}
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BlockT *getHeader() const { return Blocks.front(); }
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LoopT *getParentLoop() const { return ParentLoop; }
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/// setParentLoop is a raw interface for bypassing addChildLoop.
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void setParentLoop(LoopT *L) { ParentLoop = L; }
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/// contains - Return true if the specified loop is contained within in
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/// this loop.
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///
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bool contains(const LoopT *L) const {
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if (L == this) return true;
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if (!L) return false;
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return contains(L->getParentLoop());
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}
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/// contains - Return true if the specified basic block is in this loop.
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///
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bool contains(const BlockT *BB) const {
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return DenseBlockSet.count(BB);
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}
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/// contains - Return true if the specified instruction is in this loop.
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///
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template<class InstT>
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bool contains(const InstT *Inst) const {
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return contains(Inst->getParent());
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}
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/// iterator/begin/end - Return the loops contained entirely within this loop.
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///
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const std::vector<LoopT *> &getSubLoops() const { return SubLoops; }
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std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; }
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typedef typename std::vector<LoopT *>::const_iterator iterator;
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typedef typename std::vector<LoopT *>::const_reverse_iterator
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reverse_iterator;
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iterator begin() const { return SubLoops.begin(); }
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iterator end() const { return SubLoops.end(); }
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reverse_iterator rbegin() const { return SubLoops.rbegin(); }
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reverse_iterator rend() const { return SubLoops.rend(); }
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bool empty() const { return SubLoops.empty(); }
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/// getBlocks - Get a list of the basic blocks which make up this loop.
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///
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const std::vector<BlockT*> &getBlocks() const { return Blocks; }
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typedef typename std::vector<BlockT*>::const_iterator block_iterator;
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block_iterator block_begin() const { return Blocks.begin(); }
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block_iterator block_end() const { return Blocks.end(); }
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/// getNumBlocks - Get the number of blocks in this loop in constant time.
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unsigned getNumBlocks() const {
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return Blocks.size();
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}
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/// isLoopExiting - True if terminator in the block can branch to another
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/// block that is outside of the current loop.
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///
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bool isLoopExiting(const BlockT *BB) const {
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typedef GraphTraits<const BlockT*> BlockTraits;
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for (typename BlockTraits::ChildIteratorType SI =
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BlockTraits::child_begin(BB),
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SE = BlockTraits::child_end(BB); SI != SE; ++SI) {
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if (!contains(*SI))
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return true;
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}
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return false;
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}
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/// getNumBackEdges - Calculate the number of back edges to the loop header
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///
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unsigned getNumBackEdges() const {
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unsigned NumBackEdges = 0;
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BlockT *H = getHeader();
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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for (typename InvBlockTraits::ChildIteratorType I =
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InvBlockTraits::child_begin(H),
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E = InvBlockTraits::child_end(H); I != E; ++I)
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if (contains(*I))
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++NumBackEdges;
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return NumBackEdges;
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}
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//===--------------------------------------------------------------------===//
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// APIs for simple analysis of the loop.
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//
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// Note that all of these methods can fail on general loops (ie, there may not
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// be a preheader, etc). For best success, the loop simplification and
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// induction variable canonicalization pass should be used to normalize loops
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// for easy analysis. These methods assume canonical loops.
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/// getExitingBlocks - Return all blocks inside the loop that have successors
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/// outside of the loop. These are the blocks _inside of the current loop_
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/// which branch out. The returned list is always unique.
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///
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void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
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/// getExitingBlock - If getExitingBlocks would return exactly one block,
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/// return that block. Otherwise return null.
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BlockT *getExitingBlock() const;
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/// getExitBlocks - Return all of the successor blocks of this loop. These
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/// are the blocks _outside of the current loop_ which are branched to.
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///
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void getExitBlocks(SmallVectorImpl<BlockT*> &ExitBlocks) const;
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/// getExitBlock - If getExitBlocks would return exactly one block,
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/// return that block. Otherwise return null.
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BlockT *getExitBlock() const;
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/// Edge type.
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typedef std::pair<const BlockT*, const BlockT*> Edge;
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/// getExitEdges - Return all pairs of (_inside_block_,_outside_block_).
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void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
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/// getLoopPreheader - If there is a preheader for this loop, return it. A
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/// loop has a preheader if there is only one edge to the header of the loop
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/// from outside of the loop. If this is the case, the block branching to the
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/// header of the loop is the preheader node.
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///
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/// This method returns null if there is no preheader for the loop.
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///
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BlockT *getLoopPreheader() const;
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/// getLoopPredecessor - If the given loop's header has exactly one unique
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/// predecessor outside the loop, return it. Otherwise return null.
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/// This is less strict that the loop "preheader" concept, which requires
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/// the predecessor to have exactly one successor.
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///
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BlockT *getLoopPredecessor() const;
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/// getLoopLatch - If there is a single latch block for this loop, return it.
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/// A latch block is a block that contains a branch back to the header.
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BlockT *getLoopLatch() const;
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/// getLoopLatches - Return all loop latch blocks of this loop. A latch block
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/// is a block that contains a branch back to the header.
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void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
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BlockT *H = getHeader();
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typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
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for (typename InvBlockTraits::ChildIteratorType I =
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InvBlockTraits::child_begin(H),
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E = InvBlockTraits::child_end(H); I != E; ++I)
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if (contains(*I))
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LoopLatches.push_back(*I);
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}
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//===--------------------------------------------------------------------===//
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// APIs for updating loop information after changing the CFG
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//
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/// addBasicBlockToLoop - This method is used by other analyses to update loop
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/// information. NewBB is set to be a new member of the current loop.
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/// Because of this, it is added as a member of all parent loops, and is added
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/// to the specified LoopInfo object as being in the current basic block. It
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/// is not valid to replace the loop header with this method.
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///
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void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
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/// replaceChildLoopWith - This is used when splitting loops up. It replaces
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/// the OldChild entry in our children list with NewChild, and updates the
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/// parent pointer of OldChild to be null and the NewChild to be this loop.
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/// This updates the loop depth of the new child.
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void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
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/// addChildLoop - Add the specified loop to be a child of this loop. This
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/// updates the loop depth of the new child.
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///
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void addChildLoop(LoopT *NewChild) {
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assert(!NewChild->ParentLoop && "NewChild already has a parent!");
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NewChild->ParentLoop = static_cast<LoopT *>(this);
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SubLoops.push_back(NewChild);
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}
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/// removeChildLoop - This removes the specified child from being a subloop of
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/// this loop. The loop is not deleted, as it will presumably be inserted
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/// into another loop.
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LoopT *removeChildLoop(iterator I) {
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assert(I != SubLoops.end() && "Cannot remove end iterator!");
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LoopT *Child = *I;
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assert(Child->ParentLoop == this && "Child is not a child of this loop!");
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SubLoops.erase(SubLoops.begin()+(I-begin()));
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Child->ParentLoop = nullptr;
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return Child;
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}
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/// addBlockEntry - This adds a basic block directly to the basic block list.
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/// This should only be used by transformations that create new loops. Other
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/// transformations should use addBasicBlockToLoop.
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void addBlockEntry(BlockT *BB) {
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Blocks.push_back(BB);
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DenseBlockSet.insert(BB);
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}
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/// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop
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void reverseBlock(unsigned from) {
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std::reverse(Blocks.begin() + from, Blocks.end());
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}
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/// reserveBlocks- interface to do reserve() for Blocks
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void reserveBlocks(unsigned size) {
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Blocks.reserve(size);
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}
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/// moveToHeader - This method is used to move BB (which must be part of this
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/// loop) to be the loop header of the loop (the block that dominates all
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/// others).
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void moveToHeader(BlockT *BB) {
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if (Blocks[0] == BB) return;
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for (unsigned i = 0; ; ++i) {
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assert(i != Blocks.size() && "Loop does not contain BB!");
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if (Blocks[i] == BB) {
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Blocks[i] = Blocks[0];
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Blocks[0] = BB;
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return;
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}
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}
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}
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/// removeBlockFromLoop - This removes the specified basic block from the
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/// current loop, updating the Blocks as appropriate. This does not update
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/// the mapping in the LoopInfo class.
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void removeBlockFromLoop(BlockT *BB) {
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auto I = std::find(Blocks.begin(), Blocks.end(), BB);
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assert(I != Blocks.end() && "N is not in this list!");
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Blocks.erase(I);
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DenseBlockSet.erase(BB);
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}
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/// verifyLoop - Verify loop structure
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void verifyLoop() const;
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/// verifyLoop - Verify loop structure of this loop and all nested loops.
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void verifyLoopNest(DenseSet<const LoopT*> *Loops) const;
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void print(raw_ostream &OS, unsigned Depth = 0) const;
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protected:
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friend class LoopInfoBase<BlockT, LoopT>;
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explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
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Blocks.push_back(BB);
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DenseBlockSet.insert(BB);
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}
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};
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template<class BlockT, class LoopT>
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raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
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Loop.print(OS);
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return OS;
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}
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// Implementation in LoopInfoImpl.h
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#ifdef __GNUC__
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__extension__ extern template class LoopBase<BasicBlock, Loop>;
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#endif
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class Loop : public LoopBase<BasicBlock, Loop> {
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public:
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Loop() {}
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/// isLoopInvariant - Return true if the specified value is loop invariant
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///
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bool isLoopInvariant(const Value *V) const;
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/// hasLoopInvariantOperands - Return true if all the operands of the
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/// specified instruction are loop invariant.
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bool hasLoopInvariantOperands(const Instruction *I) const;
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/// makeLoopInvariant - If the given value is an instruction inside of the
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/// loop and it can be hoisted, do so to make it trivially loop-invariant.
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/// Return true if the value after any hoisting is loop invariant. This
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/// function can be used as a slightly more aggressive replacement for
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/// isLoopInvariant.
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///
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/// If InsertPt is specified, it is the point to hoist instructions to.
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/// If null, the terminator of the loop preheader is used.
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///
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bool makeLoopInvariant(Value *V, bool &Changed,
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Instruction *InsertPt = nullptr) const;
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/// makeLoopInvariant - If the given instruction is inside of the
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/// loop and it can be hoisted, do so to make it trivially loop-invariant.
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/// Return true if the instruction after any hoisting is loop invariant. This
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/// function can be used as a slightly more aggressive replacement for
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/// isLoopInvariant.
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///
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/// If InsertPt is specified, it is the point to hoist instructions to.
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/// If null, the terminator of the loop preheader is used.
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///
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bool makeLoopInvariant(Instruction *I, bool &Changed,
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Instruction *InsertPt = nullptr) const;
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/// getCanonicalInductionVariable - Check to see if the loop has a canonical
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/// induction variable: an integer recurrence that starts at 0 and increments
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/// by one each time through the loop. If so, return the phi node that
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/// corresponds to it.
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///
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/// The IndVarSimplify pass transforms loops to have a canonical induction
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/// variable.
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///
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PHINode *getCanonicalInductionVariable() const;
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/// isLCSSAForm - Return true if the Loop is in LCSSA form
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bool isLCSSAForm(DominatorTree &DT) const;
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/// isLoopSimplifyForm - Return true if the Loop is in the form that
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/// the LoopSimplify form transforms loops to, which is sometimes called
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/// normal form.
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bool isLoopSimplifyForm() const;
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/// isSafeToClone - Return true if the loop body is safe to clone in practice.
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bool isSafeToClone() const;
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/// Returns true if the loop is annotated parallel.
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///
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/// A parallel loop can be assumed to not contain any dependencies between
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/// iterations by the compiler. That is, any loop-carried dependency checking
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/// can be skipped completely when parallelizing the loop on the target
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/// machine. Thus, if the parallel loop information originates from the
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/// programmer, e.g. via the OpenMP parallel for pragma, it is the
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/// programmer's responsibility to ensure there are no loop-carried
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/// dependencies. The final execution order of the instructions across
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/// iterations is not guaranteed, thus, the end result might or might not
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/// implement actual concurrent execution of instructions across multiple
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/// iterations.
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bool isAnnotatedParallel() const;
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/// Return the llvm.loop loop id metadata node for this loop if it is present.
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///
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/// If this loop contains the same llvm.loop metadata on each branch to the
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/// header then the node is returned. If any latch instruction does not
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/// contain llvm.loop or or if multiple latches contain different nodes then
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/// 0 is returned.
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MDNode *getLoopID() const;
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/// Set the llvm.loop loop id metadata for this loop.
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///
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/// The LoopID metadata node will be added to each terminator instruction in
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/// the loop that branches to the loop header.
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///
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/// The LoopID metadata node should have one or more operands and the first
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/// operand should should be the node itself.
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void setLoopID(MDNode *LoopID) const;
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/// hasDedicatedExits - Return true if no exit block for the loop
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/// has a predecessor that is outside the loop.
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bool hasDedicatedExits() const;
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/// getUniqueExitBlocks - Return all unique successor blocks of this loop.
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/// These are the blocks _outside of the current loop_ which are branched to.
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/// This assumes that loop exits are in canonical form.
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///
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void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const;
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/// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one
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/// block, return that block. Otherwise return null.
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BasicBlock *getUniqueExitBlock() const;
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void dump() const;
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/// \brief Return the debug location of the start of this loop.
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/// This looks for a BB terminating instruction with a known debug
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/// location by looking at the preheader and header blocks. If it
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/// cannot find a terminating instruction with location information,
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/// it returns an unknown location.
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DebugLoc getStartLoc() const {
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BasicBlock *HeadBB;
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// Try the pre-header first.
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if ((HeadBB = getLoopPreheader()) != nullptr)
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if (DebugLoc DL = HeadBB->getTerminator()->getDebugLoc())
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return DL;
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// If we have no pre-header or there are no instructions with debug
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// info in it, try the header.
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HeadBB = getHeader();
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if (HeadBB)
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return HeadBB->getTerminator()->getDebugLoc();
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return DebugLoc();
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}
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private:
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friend class LoopInfoBase<BasicBlock, Loop>;
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explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
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};
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//===----------------------------------------------------------------------===//
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/// LoopInfo - This class builds and contains all of the top level loop
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/// structures in the specified function.
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///
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template<class BlockT, class LoopT>
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class LoopInfoBase {
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// BBMap - Mapping of basic blocks to the inner most loop they occur in
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DenseMap<const BlockT *, LoopT *> BBMap;
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std::vector<LoopT *> TopLevelLoops;
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friend class LoopBase<BlockT, LoopT>;
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friend class LoopInfo;
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void operator=(const LoopInfoBase &) = delete;
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LoopInfoBase(const LoopInfoBase &) = delete;
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public:
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LoopInfoBase() { }
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~LoopInfoBase() { releaseMemory(); }
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LoopInfoBase(LoopInfoBase &&Arg)
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: BBMap(std::move(Arg.BBMap)),
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TopLevelLoops(std::move(Arg.TopLevelLoops)) {
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// We have to clear the arguments top level loops as we've taken ownership.
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Arg.TopLevelLoops.clear();
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}
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LoopInfoBase &operator=(LoopInfoBase &&RHS) {
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BBMap = std::move(RHS.BBMap);
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for (auto *L : TopLevelLoops)
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delete L;
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TopLevelLoops = std::move(RHS.TopLevelLoops);
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RHS.TopLevelLoops.clear();
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return *this;
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}
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void releaseMemory() {
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BBMap.clear();
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for (auto *L : TopLevelLoops)
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delete L;
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TopLevelLoops.clear();
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}
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/// iterator/begin/end - The interface to the top-level loops in the current
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/// function.
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///
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typedef typename std::vector<LoopT *>::const_iterator iterator;
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typedef typename std::vector<LoopT *>::const_reverse_iterator
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reverse_iterator;
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iterator begin() const { return TopLevelLoops.begin(); }
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iterator end() const { return TopLevelLoops.end(); }
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reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
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reverse_iterator rend() const { return TopLevelLoops.rend(); }
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bool empty() const { return TopLevelLoops.empty(); }
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/// getLoopFor - Return the inner most loop that BB lives in. If a basic
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/// block is in no loop (for example the entry node), null is returned.
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///
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LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
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/// operator[] - same as getLoopFor...
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///
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const LoopT *operator[](const BlockT *BB) const {
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return getLoopFor(BB);
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}
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/// getLoopDepth - Return the loop nesting level of the specified block. A
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/// depth of 0 means the block is not inside any loop.
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///
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unsigned getLoopDepth(const BlockT *BB) const {
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const LoopT *L = getLoopFor(BB);
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return L ? L->getLoopDepth() : 0;
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}
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// isLoopHeader - True if the block is a loop header node
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bool isLoopHeader(const BlockT *BB) const {
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const LoopT *L = getLoopFor(BB);
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return L && L->getHeader() == BB;
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}
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/// removeLoop - This removes the specified top-level loop from this loop info
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/// object. The loop is not deleted, as it will presumably be inserted into
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/// another loop.
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LoopT *removeLoop(iterator I) {
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assert(I != end() && "Cannot remove end iterator!");
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LoopT *L = *I;
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assert(!L->getParentLoop() && "Not a top-level loop!");
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TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin()));
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return L;
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}
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/// changeLoopFor - Change the top-level loop that contains BB to the
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/// specified loop. This should be used by transformations that restructure
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/// the loop hierarchy tree.
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void changeLoopFor(BlockT *BB, LoopT *L) {
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if (!L) {
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BBMap.erase(BB);
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return;
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}
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BBMap[BB] = L;
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}
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/// changeTopLevelLoop - Replace the specified loop in the top-level loops
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/// list with the indicated loop.
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void changeTopLevelLoop(LoopT *OldLoop,
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LoopT *NewLoop) {
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auto I = std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop);
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assert(I != TopLevelLoops.end() && "Old loop not at top level!");
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*I = NewLoop;
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assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
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"Loops already embedded into a subloop!");
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}
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/// addTopLevelLoop - This adds the specified loop to the collection of
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/// top-level loops.
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void addTopLevelLoop(LoopT *New) {
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assert(!New->getParentLoop() && "Loop already in subloop!");
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TopLevelLoops.push_back(New);
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}
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/// removeBlock - This method completely removes BB from all data structures,
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/// including all of the Loop objects it is nested in and our mapping from
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/// BasicBlocks to loops.
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void removeBlock(BlockT *BB) {
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auto I = BBMap.find(BB);
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if (I != BBMap.end()) {
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for (LoopT *L = I->second; L; L = L->getParentLoop())
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L->removeBlockFromLoop(BB);
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BBMap.erase(I);
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}
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}
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// Internals
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static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
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const LoopT *ParentLoop) {
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if (!SubLoop) return true;
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if (SubLoop == ParentLoop) return false;
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return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
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}
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/// Create the loop forest using a stable algorithm.
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void Analyze(DominatorTreeBase<BlockT> &DomTree);
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// Debugging
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void print(raw_ostream &OS) const;
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void verify() const;
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};
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// Implementation in LoopInfoImpl.h
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#ifdef __GNUC__
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__extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
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#endif
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class LoopInfo : public LoopInfoBase<BasicBlock, Loop> {
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typedef LoopInfoBase<BasicBlock, Loop> BaseT;
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friend class LoopBase<BasicBlock, Loop>;
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void operator=(const LoopInfo &) = delete;
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LoopInfo(const LoopInfo &) = delete;
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public:
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LoopInfo() {}
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LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast<BaseT &>(Arg))) {}
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LoopInfo &operator=(LoopInfo &&RHS) {
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BaseT::operator=(std::move(static_cast<BaseT &>(RHS)));
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return *this;
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}
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// Most of the public interface is provided via LoopInfoBase.
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/// updateUnloop - Update LoopInfo after removing the last backedge from a
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/// loop--now the "unloop". This updates the loop forest and parent loops for
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/// each block so that Unloop is no longer referenced, but the caller must
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/// actually delete the Unloop object.
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void updateUnloop(Loop *Unloop);
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/// replacementPreservesLCSSAForm - Returns true if replacing From with To
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/// everywhere is guaranteed to preserve LCSSA form.
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bool replacementPreservesLCSSAForm(Instruction *From, Value *To) {
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// Preserving LCSSA form is only problematic if the replacing value is an
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// instruction.
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Instruction *I = dyn_cast<Instruction>(To);
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if (!I) return true;
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// If both instructions are defined in the same basic block then replacement
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// cannot break LCSSA form.
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if (I->getParent() == From->getParent())
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return true;
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// If the instruction is not defined in a loop then it can safely replace
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// anything.
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Loop *ToLoop = getLoopFor(I->getParent());
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if (!ToLoop) return true;
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// If the replacing instruction is defined in the same loop as the original
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// instruction, or in a loop that contains it as an inner loop, then using
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// it as a replacement will not break LCSSA form.
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return ToLoop->contains(getLoopFor(From->getParent()));
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}
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};
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// Allow clients to walk the list of nested loops...
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template <> struct GraphTraits<const Loop*> {
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typedef const Loop NodeType;
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typedef LoopInfo::iterator ChildIteratorType;
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static NodeType *getEntryNode(const Loop *L) { return L; }
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static inline ChildIteratorType child_begin(NodeType *N) {
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return N->begin();
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}
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static inline ChildIteratorType child_end(NodeType *N) {
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return N->end();
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}
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};
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template <> struct GraphTraits<Loop*> {
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typedef Loop NodeType;
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typedef LoopInfo::iterator ChildIteratorType;
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static NodeType *getEntryNode(Loop *L) { return L; }
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static inline ChildIteratorType child_begin(NodeType *N) {
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return N->begin();
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}
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static inline ChildIteratorType child_end(NodeType *N) {
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return N->end();
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}
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};
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/// \brief Analysis pass that exposes the \c LoopInfo for a function.
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class LoopAnalysis {
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static char PassID;
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public:
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typedef LoopInfo Result;
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/// \brief Opaque, unique identifier for this analysis pass.
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static void *ID() { return (void *)&PassID; }
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/// \brief Provide a name for the analysis for debugging and logging.
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static StringRef name() { return "LoopAnalysis"; }
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LoopInfo run(Function &F, AnalysisManager<Function> *AM);
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};
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/// \brief Printer pass for the \c LoopAnalysis results.
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class LoopPrinterPass {
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raw_ostream &OS;
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public:
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explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {}
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PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
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static StringRef name() { return "LoopPrinterPass"; }
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};
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/// \brief The legacy pass manager's analysis pass to compute loop information.
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class LoopInfoWrapperPass : public FunctionPass {
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LoopInfo LI;
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public:
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static char ID; // Pass identification, replacement for typeid
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LoopInfoWrapperPass() : FunctionPass(ID) {
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initializeLoopInfoWrapperPassPass(*PassRegistry::getPassRegistry());
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}
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LoopInfo &getLoopInfo() { return LI; }
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const LoopInfo &getLoopInfo() const { return LI; }
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/// \brief Calculate the natural loop information for a given function.
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bool runOnFunction(Function &F) override;
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void verifyAnalysis() const override;
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void releaseMemory() override { LI.releaseMemory(); }
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void print(raw_ostream &O, const Module *M = nullptr) const override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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};
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} // End llvm namespace
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#endif
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