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//===- CloneLoop.cpp - Clone loop nest ------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CloneLoop interface which makes a copy of a loop.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/BasicBlock.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/ADT/DenseMap.h"
using namespace llvm;
/// CloneDominatorInfo - Clone basicblock's dominator tree and, if available,
/// dominance info. It is expected that basic block is already cloned.
static void CloneDominatorInfo(BasicBlock *BB,
DenseMap<const Value *, Value *> &ValueMap,
DominatorTree *DT,
DominanceFrontier *DF) {
assert (DT && "DominatorTree is not available");
DenseMap<const Value *, Value*>::iterator BI = ValueMap.find(BB);
assert (BI != ValueMap.end() && "BasicBlock clone is missing");
BasicBlock *NewBB = cast<BasicBlock>(BI->second);
// NewBB already got dominator info.
if (DT->getNode(NewBB))
return;
assert (DT->getNode(BB) && "BasicBlock does not have dominator info");
// Entry block is not expected here. Infinite loops are not to cloned.
assert (DT->getNode(BB)->getIDom() && "BasicBlock does not have immediate dominator");
BasicBlock *BBDom = DT->getNode(BB)->getIDom()->getBlock();
// NewBB's dominator is either BB's dominator or BB's dominator's clone.
BasicBlock *NewBBDom = BBDom;
DenseMap<const Value *, Value*>::iterator BBDomI = ValueMap.find(BBDom);
if (BBDomI != ValueMap.end()) {
NewBBDom = cast<BasicBlock>(BBDomI->second);
if (!DT->getNode(NewBBDom))
CloneDominatorInfo(BBDom, ValueMap, DT, DF);
}
DT->addNewBlock(NewBB, NewBBDom);
// Copy cloned dominance frontiner set
if (DF) {
DominanceFrontier::DomSetType NewDFSet;
DominanceFrontier::iterator DFI = DF->find(BB);
if ( DFI != DF->end()) {
DominanceFrontier::DomSetType S = DFI->second;
for (DominanceFrontier::DomSetType::iterator I = S.begin(), E = S.end();
I != E; ++I) {
BasicBlock *DB = *I;
DenseMap<const Value*, Value*>::iterator IDM = ValueMap.find(DB);
if (IDM != ValueMap.end())
NewDFSet.insert(cast<BasicBlock>(IDM->second));
else
NewDFSet.insert(DB);
}
}
DF->addBasicBlock(NewBB, NewDFSet);
}
}
/// CloneLoop - Clone Loop. Clone dominator info. Populate ValueMap
/// using old blocks to new blocks mapping.
Loop *llvm::CloneLoop(Loop *OrigL, LPPassManager *LPM, LoopInfo *LI,
DenseMap<const Value *, Value *> &ValueMap, Pass *P) {
DominatorTree *DT = NULL;
DominanceFrontier *DF = NULL;
if (P) {
DT = P->getAnalysisToUpdate<DominatorTree>();
DF = P->getAnalysisToUpdate<DominanceFrontier>();
}
SmallVector<BasicBlock *, 16> NewBlocks;
// Populate loop nest.
SmallVector<Loop *, 8> LoopNest;
LoopNest.push_back(OrigL);
Loop *NewParentLoop = NULL;
while (!LoopNest.empty()) {
Loop *L = LoopNest.back();
LoopNest.pop_back();
Loop *NewLoop = new Loop();
if (!NewParentLoop)
NewParentLoop = NewLoop;
LPM->insertLoop(NewLoop, L->getParentLoop());
// Clone Basic Blocks.
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I) {
BasicBlock *BB = *I;
BasicBlock *NewBB = CloneBasicBlock(BB, ValueMap, ".clone");
ValueMap[BB] = NewBB;
if (P)
LPM->cloneBasicBlockSimpleAnalysis(BB, NewBB, L);
NewLoop->addBasicBlockToLoop(NewBB, LI->getBase());
NewBlocks.push_back(NewBB);
}
// Clone dominator info.
if (DT)
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I) {
BasicBlock *BB = *I;
CloneDominatorInfo(BB, ValueMap, DT, DF);
}
// Process sub loops
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
LoopNest.push_back(*I);
}
// Remap instructions to reference operands from ValueMap.
for(SmallVector<BasicBlock *, 16>::iterator NBItr = NewBlocks.begin(),
NBE = NewBlocks.end(); NBItr != NBE; ++NBItr) {
BasicBlock *NB = *NBItr;
for(BasicBlock::iterator BI = NB->begin(), BE = NB->end();
BI != BE; ++BI) {
Instruction *Insn = BI;
for (unsigned index = 0, num_ops = Insn->getNumOperands();
index != num_ops; ++index) {
Value *Op = Insn->getOperand(index);
DenseMap<const Value *, Value *>::iterator OpItr = ValueMap.find(Op);
if (OpItr != ValueMap.end())
Insn->setOperand(index, OpItr->second);
}
}
}
BasicBlock *Latch = OrigL->getLoopLatch();
Function *F = Latch->getParent();
F->getBasicBlockList().insert(OrigL->getHeader(),
NewBlocks.begin(), NewBlocks.end());
return NewParentLoop;
}
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