//===- LoopIndexSplit.cpp - Loop Index Splitting Pass ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Devang Patel and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements Loop Index Splitting Pass.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-index-split"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
STATISTIC(NumIndexSplit, "Number of loops index split");
namespace {
class VISIBILITY_HIDDEN LoopIndexSplit : public LoopPass {
public:
static char ID; // Pass ID, replacement for typeid
LoopIndexSplit() : LoopPass((intptr_t)&ID) {}
// Index split Loop L. Return true if loop is split.
bool runOnLoop(Loop *L, LPPassManager &LPM);
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<ScalarEvolution>();
AU.addPreserved<ScalarEvolution>();
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addRequired<LoopInfo>();
AU.addPreserved<LoopInfo>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequired<DominatorTree>();
AU.addRequired<DominanceFrontier>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<DominanceFrontier>();
}
private:
class SplitInfo {
public:
SplitInfo() : SplitValue(NULL), SplitCondition(NULL),
UseTrueBranchFirst(true), A_ExitValue(NULL),
B_StartValue(NULL) {}
// Induction variable's range is split at this value.
Value *SplitValue;
// This compare instruction compares IndVar against SplitValue.
ICmpInst *SplitCondition;
// True if after loop index split, first loop will execute split condition's
// true branch.
bool UseTrueBranchFirst;
// Exit value for first loop after loop split.
Value *A_ExitValue;
// Start value for second loop after loop split.
Value *B_StartValue;
// Clear split info.
void clear() {
SplitValue = NULL;
SplitCondition = NULL;
UseTrueBranchFirst = true;
A_ExitValue = NULL;
B_StartValue = NULL;
}
};
private:
