//
// 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.
+// contained entirely within the loop and the basic blocks the make up 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.
+// It can calculate on the fly various bits of information, for example:
+//
+// * whether there is a preheader for the loop
+// * the number of back edges to the header
+// * whether or not a particular block branches out of the loop
+// * the successor blocks of the loop
+// * the loop depth
+// * the trip count
+// * etc...
//
//===----------------------------------------------------------------------===//
#define LLVM_ANALYSIS_LOOP_INFO_H
#include "llvm/Pass.h"
-#include "Support/GraphTraits.h"
-#include <set>
+#include "llvm/ADT/GraphTraits.h"
namespace llvm {
-class DominatorSet;
+struct DominatorSet;
class LoopInfo;
class PHINode;
- class Instruction;
+class Instruction;
//===----------------------------------------------------------------------===//
/// Loop class - Instances of this class are used to represent loops that are
Loop *ParentLoop;
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:
/// Loop ctor - This creates an empty loop.
- Loop() : ParentLoop(0), LoopDepth(0) {
- }
+ Loop() : ParentLoop(0) {}
~Loop() {
for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
delete SubLoops[i];
}
- unsigned getLoopDepth() const { return LoopDepth; }
+ unsigned getLoopDepth() const {
+ unsigned D = 0;
+ for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop)
+ ++D;
+ return D;
+ }
BasicBlock *getHeader() const { return Blocks.front(); }
Loop *getParentLoop() const { return ParentLoop; }
/// 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; }
+ typedef std::vector<BasicBlock*>::const_iterator block_iterator;
+ block_iterator block_begin() const { return Blocks.begin(); }
+ block_iterator block_end() const { return Blocks.end(); }
/// isLoopExit - True if terminator in the block can branch to another block
- /// that is outside of the current loop. The reached block should be in the
- /// ExitBlocks list.
+ /// that is outside of the current loop.
///
bool isLoopExit(const BasicBlock *BB) const;
///
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;
- }
+ /// isLoopInvariant - Return true if the specified value is loop invariant
+ ///
+ bool isLoopInvariant(Value *V) const;
//===--------------------------------------------------------------------===//
// APIs for simple analysis of the loop.
// induction variable canonicalization pass should be used to normalize loops
// for easy analysis. These methods assume canonical loops.
+ /// getExitBlocks - Return all of the successor blocks of this loop. These
+ /// are the blocks _outside of the current loop_ which are branched to.
+ ///
+ void getExitBlocks(std::vector<BasicBlock*> &Blocks) const;
+
/// 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
///
void addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI);
- /// 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);
-
/// replaceChildLoopWith - This is used when splitting loops up. It replaces
/// the OldChild entry in our children list with NewChild, and updates the
/// parent pointer of OldChild to be null and the NewChild to be this loop.
/// into another loop.
Loop *removeChildLoop(iterator OldChild);
- /// addExitBlock - Add the specified exit block to the loop.
- ///
- void addExitBlock(BasicBlock *BB) {
- ExitBlocks.push_back(BB);
- }
-
/// addBlockEntry - This adds a basic block directly to the basic block list.
/// This should only be used by transformations that create new loops. Other
/// transformations should use addBasicBlockToLoop.
}
/// removeBlockFromLoop - This removes the specified basic block from the
- /// current loop, updating the Blocks and ExitBlocks lists as appropriate.
- /// This does not update the mapping in the LoopInfo class.
+ /// current loop, updating the Blocks as appropriate. This does not update
+ /// the mapping in the LoopInfo class.
void removeBlockFromLoop(BasicBlock *BB);
void print(std::ostream &O, unsigned Depth = 0) const;
private:
friend class LoopInfo;
Loop(BasicBlock *BB) : ParentLoop(0) {
- Blocks.push_back(BB); LoopDepth = 0;
- }
- void setLoopDepth(unsigned Level) {
- LoopDepth = Level;
- for (unsigned i = 0, e = SubLoops.size(); i != e; ++i)
- SubLoops[i]->setLoopDepth(Level+1);
+ Blocks.push_back(BB);
}
};
/// getLoopFor - Return the inner most loop that BB lives in. If a basic
/// block is in no loop (for example the entry node), null is returned.
///
- const Loop *getLoopFor(const BasicBlock *BB) const {
+ Loop *getLoopFor(const BasicBlock *BB) const {
std::map<BasicBlock *, Loop*>::const_iterator I=BBMap.find((BasicBlock*)BB);
return I != BBMap.end() ? I->second : 0;
}
/// operator[] - same as getLoopFor...
///
- inline const Loop *operator[](const BasicBlock *BB) const {
+ const Loop *operator[](const BasicBlock *BB) const {
return getLoopFor(BB);
}
/// list with the indicated loop.
void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop);
+ /// addTopLevelLoop - This adds the specified loop to the collection of
+ /// top-level loops.
+ void addTopLevelLoop(Loop *New) {
+ assert(New->getParentLoop() == 0 && "Loop already in subloop!");
+ TopLevelLoops.push_back(New);
+ }
+
+ /// removeBlock - This method completely removes BB from all data structures,
+ /// including all of the Loop objects it is nested in and our mapping from
+ /// BasicBlocks to loops.
+ void removeBlock(BasicBlock *BB);
+
static void stub(); // Noop
private:
void Calculate(const DominatorSet &DS);
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