//===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator --------*- C++ -*--=//
//
// 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 the
-// loops identified may actually be several natural loops that share the same
-// header node... not just a single natural loop.
+// and determine the loop depth of various nodes of the CFG. 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.
+//
+// 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.
//
//===----------------------------------------------------------------------===//
#define LLVM_ANALYSIS_LOOP_INFO_H
#include "llvm/Pass.h"
+#include "Support/GraphTraits.h"
#include <set>
class DominatorSet;
///
class Loop {
Loop *ParentLoop;
- std::vector<BasicBlock *> Blocks; // First entry is the header node
std::vector<Loop*> SubLoops; // Loops contained entirely within this one
+ std::vector<BasicBlock*> Blocks; // First entry is the header node
+ std::vector<BasicBlock*> ExitBlocks; // Reachable blocks outside the loop
unsigned LoopDepth; // Nesting depth of this loop
Loop(const Loop &); // DO NOT IMPLEMENT
const Loop &operator=(const Loop &); // DO NOT IMPLEMENT
public:
- inline unsigned getLoopDepth() const { return LoopDepth; }
- inline BasicBlock *getHeader() const { return Blocks.front(); }
- inline Loop *getParentLoop() const { return ParentLoop; }
+ unsigned getLoopDepth() const { return LoopDepth; }
+ BasicBlock *getHeader() const { return Blocks.front(); }
+ Loop *getParentLoop() const { return ParentLoop; }
/// contains - Return true of the specified basic block is in this loop
bool contains(const BasicBlock *BB) const;
/// getSubLoops - Return the loops contained entirely within this loop
///
- inline const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
- inline const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
+ const std::vector<Loop*> &getSubLoops() const { return SubLoops; }
+
+ /// getBlocks - Get a list of the basic blocks which make up this loop.
+ ///
+ const std::vector<BasicBlock*> &getBlocks() const { return Blocks; }
+
+ /// getExitBlocks - Return all of the successor blocks of this loop. These
+ /// are the blocks _outside of the current loop_ which are branched to.
+ ///
+ const std::vector<BasicBlock*> &getExitBlocks() const { return ExitBlocks; }
/// isLoopExit - True if terminator in the block can branch to another block
- /// that is outside of the current loop.
+ /// that is outside of the current loop. The reached block should be in the
+ /// ExitBlocks list.
+ ///
bool isLoopExit(const BasicBlock *BB) const;
- /// Find number of back edges
+ /// getNumBackEdges - Calculate the number of back edges to the loop header
+ ///
unsigned getNumBackEdges() const;
+ /// hasExitBlock - Return true if the current loop has the specified block as
+ /// an exit block...
+ bool hasExitBlock(BasicBlock *BB) const {
+ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
+ if (ExitBlocks[i] == BB)
+ return true;
+ return false;
+ }
+
/// 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
/// from outside of the loop. If this is the case, the block branching to the
///
BasicBlock *getLoopPreheader() const;
- /// addBasicBlockToLoop - This function is used by other analyses to update
- /// loop information. NewBB is set to be a new member of the current loop.
+ /// addBasicBlockToLoop - This method is used by other analyses to update loop
+ /// information. NewBB is set to be a new member of the current loop.
/// Because of this, it is added as a member of all parent loops, and is added
/// 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 print(std::ostream &O) const;
+ /// changeExitBlock - This method is used to update loop information. All
+ /// instances of the specified Old basic block are removed from the exit list
+ /// and replaced with New.
+ ///
+ void changeExitBlock(BasicBlock *Old, BasicBlock *New);
+
+ void print(std::ostream &O, unsigned Depth = 0) const;
+ void dump() const;
private:
friend class LoopInfo;
inline Loop(BasicBlock *BB) : ParentLoop(0) {
return L ? L->getLoopDepth() : 0;
}
-#if 0
// isLoopHeader - True if the block is a loop header node
bool isLoopHeader(BasicBlock *BB) const {
return getLoopFor(BB)->getHeader() == BB;
}
- // isLoopEnd - True if block jumps to loop entry
- bool isLoopEnd(BasicBlock *BB) const;
-#endif
/// runOnFunction - Calculate the natural loop information.
///
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);
};
static IncludeFile
LOOP_INFO_INCLUDE_FILE((void*)&LoopInfo::stub);
+// 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;
+
+ static NodeType *getEntryNode(const Loop *L) { return L; }
+ static inline ChildIteratorType child_begin(NodeType *N) {
+ return N->getSubLoops().begin();
+ }
+ static inline ChildIteratorType child_end(NodeType *N) {
+ return N->getSubLoops().end();
+ }
+};
+
+template <> struct GraphTraits<Loop*> {
+ typedef Loop NodeType;
+ typedef std::vector<Loop*>::const_iterator ChildIteratorType;
+
+ static NodeType *getEntryNode(Loop *L) { return L; }
+ static inline ChildIteratorType child_begin(NodeType *N) {
+ return N->getSubLoops().begin();
+ }
+ static inline ChildIteratorType child_end(NodeType *N) {
+ return N->getSubLoops().end();
+ }
+};
+
#endif
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