1 //===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator --------*- C++ -*--=//
3 // This file defines the LoopInfo class that is used to identify natural loops
4 // and determine the loop depth of various nodes of the CFG. Note that the
5 // loops identified may actually be several natural loops that share the same
6 // header node... not just a single natural loop.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_ANALYSIS_LOOP_INFO_H
11 #define LLVM_ANALYSIS_LOOP_INFO_H
22 //===----------------------------------------------------------------------===//
23 // Loop class - Instances of this class are used to represent loops that are
24 // detected in the flow graph
28 vector<const BasicBlock *> Blocks; // First entry is the header node
29 vector<Loop*> SubLoops; // Loops contained entirely within this one
30 unsigned LoopDepth; // Nesting depth of this loop
32 Loop(const Loop &); // DO NOT IMPLEMENT
33 const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
36 inline unsigned getLoopDepth() const { return LoopDepth; }
37 inline const BasicBlock *getHeader() const { return Blocks.front(); }
39 // contains - Return true of the specified basic block is in this loop
40 bool contains(const BasicBlock *BB) const;
42 // getSubLoops - Return the loops contained entirely within this loop
43 inline const vector<Loop*> &getSubLoops() const { return SubLoops; }
44 inline const vector<const BasicBlock*> &getBlocks() const { return Blocks; }
47 friend class LoopInfo;
48 inline Loop(const BasicBlock *BB) { Blocks.push_back(BB); LoopDepth = 0; }
50 void setLoopDepth(unsigned Level) {
52 for (unsigned i = 0; i < SubLoops.size(); ++i)
53 SubLoops[i]->setLoopDepth(Level+1);
59 //===----------------------------------------------------------------------===//
60 // LoopInfo - This class builds and contains all of the top level loop
61 // structures in the specified method.
64 // BBMap - Mapping of basic blocks to the inner most loop they occur in
65 map<const BasicBlock *, Loop*> BBMap;
66 vector<Loop*> TopLevelLoops;
68 // LoopInfo ctor - Calculate the natural loop information for a CFG
69 LoopInfo(const DominatorSet &DS);
71 const vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; }
73 // getLoopFor - Return the inner most loop that BB lives in. If a basic block
74 // is in no loop (for example the entry node), null is returned.
76 const Loop *getLoopFor(const BasicBlock *BB) const {
77 map<const BasicBlock *, Loop*>::const_iterator I = BBMap.find(BB);
78 return I != BBMap.end() ? I->second : 0;
80 inline const Loop *operator[](const BasicBlock *BB) const {
81 return getLoopFor(BB);
84 // getLoopDepth - Return the loop nesting level of the specified block...
85 unsigned getLoopDepth(const BasicBlock *BB) const {
86 const Loop *L = getLoopFor(BB);
87 return L ? L->getLoopDepth() : 0;
91 // isLoopHeader - True if the block is a loop header node
92 bool isLoopHeader(const BasicBlock *BB) const {
93 return getLoopFor(BB)->getHeader() == BB;
95 // isLoopEnd - True if block jumps to loop entry
96 bool isLoopEnd(const BasicBlock *BB) const;
97 // isLoopExit - True if block is the loop exit
98 bool isLoopExit(const BasicBlock *BB) const;
102 Loop *ConsiderForLoop(const BasicBlock *BB, const DominatorSet &DS);
105 } // End namespace cfg