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122 lines
4.0 KiB
C++
122 lines
4.0 KiB
C++
//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator --------*- C++ -*--=//
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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. Note that the
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// loops identified may actually be several natural loops that share the same
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// header node... not just a single natural loop.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LOOP_INFO_H
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#define LLVM_ANALYSIS_LOOP_INFO_H
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#include "llvm/Pass.h"
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#include <set>
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class DominatorSet;
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class LoopInfo;
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//===----------------------------------------------------------------------===//
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// Loop class - Instances of this class are used to represent loops that are
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// detected in the flow graph
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//
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class Loop {
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Loop *ParentLoop;
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std::vector<BasicBlock *> Blocks; // First entry is the header node
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std::vector<Loop*> SubLoops; // Loops contained entirely within this one
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unsigned LoopDepth; // Nesting depth of this loop
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Loop(const Loop &); // DO NOT IMPLEMENT
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const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
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public:
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inline unsigned getLoopDepth() const { return LoopDepth; }
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inline BasicBlock *getHeader() const { return Blocks.front(); }
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// contains - Return true of the specified basic block is in this loop
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bool contains(BasicBlock *BB) const;
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// getSubLoops - Return the loops contained entirely within this loop
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inline const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
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inline const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
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private:
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friend class LoopInfo;
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inline Loop(BasicBlock *BB) { Blocks.push_back(BB); LoopDepth = 0; }
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~Loop() {
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for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
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delete SubLoops[i];
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}
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void setLoopDepth(unsigned Level) {
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LoopDepth = Level;
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for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
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SubLoops[i]->setLoopDepth(Level+1);
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}
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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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class LoopInfo : public FunctionPass {
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// BBMap - Mapping of basic blocks to the inner most loop they occur in
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std::map<BasicBlock*, Loop*> BBMap;
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std::vector<Loop*> TopLevelLoops;
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public:
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static AnalysisID ID; // LoopInfo Analysis ID
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// LoopInfo ctor - Calculate the natural loop information for a CFG
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LoopInfo(AnalysisID id) { assert(id == ID); }
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~LoopInfo() { releaseMemory(); }
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const char *getPassName() const { return "Natural Loop Analysis"; }
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const std::vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; }
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// getLoopFor - Return the inner most loop that BB lives in. If a basic block
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// is in no loop (for example the entry node), null is returned.
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//
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const Loop *getLoopFor(BasicBlock *BB) const {
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std::map<BasicBlock *, Loop*>::const_iterator I = BBMap.find(BB);
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return I != BBMap.end() ? I->second : 0;
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}
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inline const Loop *operator[](BasicBlock *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...
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unsigned getLoopDepth(BasicBlock *BB) const {
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const Loop *L = getLoopFor(BB);
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return L ? L->getLoopDepth() : 0;
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}
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#if 0
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// isLoopHeader - True if the block is a loop header node
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bool isLoopHeader(BasicBlock *BB) const {
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return getLoopFor(BB)->getHeader() == BB;
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}
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// isLoopEnd - True if block jumps to loop entry
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bool isLoopEnd(BasicBlock *BB) const;
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// isLoopExit - True if block is the loop exit
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bool isLoopExit(BasicBlock *BB) const;
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#endif
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// runOnFunction - Pass framework implementation
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virtual bool runOnFunction(Function *F);
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virtual void releaseMemory();
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// getAnalysisUsage - Provide loop info, require dominator set
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//
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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private:
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void Calculate(const DominatorSet &DS);
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Loop *ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS);
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};
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#endif
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