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* LoopInfo now keeps track of exit blocks from the loop

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* New LoopInfo::isLoopHeader method
  * Remove some #if 0 code


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5649 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-02-27 00:37:22 +00:00
parent 8856f4c478
commit fe3ae1ed66
1 changed files with 36 additions and 14 deletions
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50
include/llvm/Analysis/LoopInfo.h
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@ -1,9 +1,17 @@
//===- 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.
//
//===----------------------------------------------------------------------===//
@ -22,8 +30,9 @@ class LoopInfo;
///
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
@ -39,14 +48,25 @@ public:
/// 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;
/// getLoopPreheader - If there is a preheader for this loop, return it. A
@ -61,14 +81,20 @@ public:
///
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);
/// changeExitBlock - This method is used to update loop information. One
/// instance of the specified Old basic block is removed from the exit list
/// and replaced with New.
///
void changeExitBlock(BasicBlock *Old, BasicBlock *New);
void print(std::ostream &O) const;
private:
friend class LoopInfo;
@ -124,14 +150,10 @@ public:
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.
///