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
13 #include "llvm/Pass.h"
19 //===----------------------------------------------------------------------===//
20 // Loop class - Instances of this class are used to represent loops that are
21 // detected in the flow graph
25 std::vector<BasicBlock *> Blocks; // First entry is the header node
26 std::vector<Loop*> SubLoops; // Loops contained entirely within this one
27 unsigned LoopDepth; // Nesting depth of this loop
29 Loop(const Loop &); // DO NOT IMPLEMENT
30 const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
33 inline unsigned getLoopDepth() const { return LoopDepth; }
34 inline BasicBlock *getHeader() const { return Blocks.front(); }
36 // contains - Return true of the specified basic block is in this loop
37 bool contains(const BasicBlock *BB) const;
39 // getSubLoops - Return the loops contained entirely within this loop
40 inline const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
41 inline const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
43 void print(std::ostream &O) const;
45 friend class LoopInfo;
46 inline Loop(BasicBlock *BB) { Blocks.push_back(BB); LoopDepth = 0; }
48 for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
52 void setLoopDepth(unsigned Level) {
54 for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
55 SubLoops[i]->setLoopDepth(Level+1);
61 //===----------------------------------------------------------------------===//
62 // LoopInfo - This class builds and contains all of the top level loop
63 // structures in the specified function.
65 class LoopInfo : public FunctionPass {
66 // BBMap - Mapping of basic blocks to the inner most loop they occur in
67 std::map<BasicBlock*, Loop*> BBMap;
68 std::vector<Loop*> TopLevelLoops;
70 // LoopInfo ctor - Calculate the natural loop information for a CFG
71 ~LoopInfo() { releaseMemory(); }
73 const std::vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; }
75 // getLoopFor - Return the inner most loop that BB lives in. If a basic block
76 // is in no loop (for example the entry node), null is returned.
78 const Loop *getLoopFor(const BasicBlock *BB) const {
79 std::map<BasicBlock *, Loop*>::const_iterator I=BBMap.find((BasicBlock*)BB);
80 return I != BBMap.end() ? I->second : 0;
82 inline const Loop *operator[](const BasicBlock *BB) const {
83 return getLoopFor(BB);
86 // getLoopDepth - Return the loop nesting level of the specified block...
87 unsigned getLoopDepth(const BasicBlock *BB) const {
88 const Loop *L = getLoopFor(BB);
89 return L ? L->getLoopDepth() : 0;
93 // isLoopHeader - True if the block is a loop header node
94 bool isLoopHeader(BasicBlock *BB) const {
95 return getLoopFor(BB)->getHeader() == BB;
97 // isLoopEnd - True if block jumps to loop entry
98 bool isLoopEnd(BasicBlock *BB) const;
99 // isLoopExit - True if block is the loop exit
100 bool isLoopExit(BasicBlock *BB) const;
103 // runOnFunction - Pass framework implementation
104 virtual bool runOnFunction(Function &F);
106 virtual void releaseMemory();
107 void print(std::ostream &O) const;
109 // getAnalysisUsage - Provide loop info, require dominator set
111 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
113 static void stub(); // Noop
115 void Calculate(const DominatorSet &DS);
116 Loop *ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS);
120 // Make sure that any clients of this file link in PostDominators.cpp
122 LOOP_INFO_INCLUDE_FILE((void*)&LoopInfo::stub);