// Induction variable's final loop exit value operand number in exit condition..
unsigned ExitValueNum;
};
-
- char LoopIndexSplit::ID = 0;
- RegisterPass<LoopIndexSplit> X ("loop-index-split", "Index Split Loops");
}
+char LoopIndexSplit::ID = 0;
+static RegisterPass<LoopIndexSplit>
+X("loop-index-split", "Index Split Loops");
+
LoopPass *llvm::createLoopIndexSplitPass() {
return new LoopIndexSplit();
}
return false;
// First see if it is possible to eliminate loop itself or not.
- for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin(),
- E = SplitData.end(); SI != E;) {
+ for (SmallVector<SplitInfo, 4>::iterator SI = SplitData.begin();
+ SI != SplitData.end();) {
SplitInfo &SD = *SI;
ICmpInst *CI = dyn_cast<ICmpInst>(SD.SplitCondition);
if (SD.SplitCondition->getOpcode() == Instruction::And) {
return Changed;
} else {
SmallVector<SplitInfo, 4>::iterator Delete_SI = SI;
- ++SI;
- SplitData.erase(Delete_SI);
+ SI = SplitData.erase(Delete_SI);
}
}
else if (CI && CI->getPredicate() == ICmpInst::ICMP_EQ) {
return Changed;
} else {
SmallVector<SplitInfo, 4>::iterator Delete_SI = SI;
- ++SI;
- SplitData.erase(Delete_SI);
+ SI = SplitData.erase(Delete_SI);
}
} else
++SI;
BasicBlock *Preheader = L->getLoopPreheader();
StartValue = IndVar->getIncomingValueForBlock(Preheader);
}
+
+ // If start value is more then exit value where induction variable
+ // increments by 1 then we are potentially dealing with an infinite loop.
+ // Do not index split this loop.
+ if (ExitCondition) {
+ ConstantInt *SV = dyn_cast<ConstantInt>(StartValue);
+ ConstantInt *EV =
+ dyn_cast<ConstantInt>(ExitCondition->getOperand(ExitValueNum));
+ if (SV && EV && SV->getSExtValue() > EV->getSExtValue())
+ ExitCondition = NULL;
+ else if (EV && EV->isZero())
+ ExitCondition = NULL;
+ }
}
/// Find condition inside a loop that is suitable candidate for index split.
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
SD.SplitValue, ExitValue, "lisplit",
Terminator);
- Instruction *NSplitCond = BinaryOperator::createAnd(C1, C2, "lisplit",
+ Instruction *NSplitCond = BinaryOperator::CreateAnd(C1, C2, "lisplit",
Terminator);
SD.SplitCondition->replaceAllUsesWith(NSplitCond);
SD.SplitCondition->eraseFromParent();
if (isa<PHINode>(I) || I == LTerminator)
continue;
- if (I == IndVarIncrement)
- I->replaceAllUsesWith(ExitValue);
- else
+ if (I == IndVarIncrement) {
+ // Replace induction variable increment if it is not used outside
+ // the loop.
+ bool UsedOutsideLoop = false;
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+ UI != E; ++UI) {
+ if (Instruction *Use = dyn_cast<Instruction>(UI))
+ if (!L->contains(Use->getParent())) {
+ UsedOutsideLoop = true;
+ break;
+ }
+ }
+ if (!UsedOutsideLoop) {
+ I->replaceAllUsesWith(ExitValue);
+ I->eraseFromParent();
+ }
+ }
+ else {
I->replaceAllUsesWith(UndefValue::get(I->getType()));
- I->eraseFromParent();
+ I->eraseFromParent();
+ }
}
LPM->deleteLoopFromQueue(L);
//
if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLT
|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
- Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
+ Value *A = BinaryOperator::CreateAdd(NV, ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
A, UB,"lsplit,c", PHTerminator);
- NUB = new SelectInst (C, A, UB, "lsplit.nub", PHTerminator);
+ NUB = SelectInst::Create(C, A, UB, "lsplit.nub", PHTerminator);
}
// for (i = LB; i <= UB; ++i)
|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
NV, UB, "lsplit.c", PHTerminator);
- NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
+ NUB = SelectInst::Create(C, NV, UB, "lsplit.nub", PHTerminator);
}
break;
case ICmpInst::ICMP_ULT:
|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULT) {
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
NV, UB, "lsplit.c", PHTerminator);
- NUB = new SelectInst (C, NV, UB, "lsplit.nub", PHTerminator);
+ NUB = SelectInst::Create(C, NV, UB, "lsplit.nub", PHTerminator);
}
// for (i = LB; i <= UB; ++i)
//
else if (ExitCondition->getPredicate() == ICmpInst::ICMP_SLE
|| ExitCondition->getPredicate() == ICmpInst::ICMP_ULE) {
- Value *S = BinaryOperator::createSub(NV, ConstantInt::get(Ty, 1, Sign),
+ Value *S = BinaryOperator::CreateSub(NV, ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
S, UB, "lsplit.c", PHTerminator);
- NUB = new SelectInst (C, S, UB, "lsplit.nub", PHTerminator);
+ NUB = SelectInst::Create(C, S, UB, "lsplit.nub", PHTerminator);
}
break;
case ICmpInst::ICMP_UGE:
{
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
NV, StartValue, "lsplit.c", PHTerminator);
- NLB = new SelectInst (C, StartValue, NV, "lsplit.nlb", PHTerminator);
+ NLB = SelectInst::Create(C, StartValue, NV, "lsplit.nlb", PHTerminator);
}
break;
case ICmpInst::ICMP_UGT:
// LOOP_BODY
//
{
- Value *A = BinaryOperator::createAdd(NV, ConstantInt::get(Ty, 1, Sign),
+ Value *A = BinaryOperator::CreateAdd(NV, ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
Value *C = new ICmpInst(Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
A, StartValue, "lsplit.c", PHTerminator);
- NLB = new SelectInst (C, StartValue, A, "lsplit.nlb", PHTerminator);
+ NLB = SelectInst::Create(C, StartValue, A, "lsplit.nlb", PHTerminator);
}
break;
default:
BasicBlock *Succ0 = SplitTerminator->getSuccessor(0);
BasicBlock *Succ1 = SplitTerminator->getSuccessor(1);
+ // If split block does not dominate the latch then this is not a diamond.
+ // Such loop may not benefit from index split.
+ if (!DT->dominates(SplitCondBlock, Latch))
+ return false;
+
// Finally this split condition is safe only if merge point for
// split condition branch is loop latch. This check along with previous
// check, to ensure that exit condition is in either loop latch or header,
// A;
// for (i = max(LB, BSV); i < UB; ++i)
// B;
- BSV = BinaryOperator::createAdd(SD.SplitValue,
+ BSV = BinaryOperator::CreateAdd(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
AEV = BSV;
// B;
// for (i = max(LB, BSV); i < UB; ++i)
// A;
- BSV = BinaryOperator::createAdd(SD.SplitValue,
+ BSV = BinaryOperator::CreateAdd(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
AEV = BSV;
// A;
// for (i = max(LB, BSV); i <= UB; ++i)
// B;
- AEV = BinaryOperator::createSub(SD.SplitValue,
+ AEV = BinaryOperator::CreateSub(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.sub", PHTerminator);
break;
// A;
// for (i = max(LB, BSV); i <= UB; ++i)
// B;
- BSV = BinaryOperator::createAdd(SD.SplitValue,
+ BSV = BinaryOperator::CreateAdd(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
break;
// B;
// for (i = max(LB, BSV); i <= UB; ++i)
// A;
- BSV = BinaryOperator::createAdd(SD.SplitValue,
+ BSV = BinaryOperator::CreateAdd(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.add", PHTerminator);
break;
// B;
// for (i = max(LB, BSV); i <= UB; ++i)
// A;
- AEV = BinaryOperator::createSub(SD.SplitValue,
+ AEV = BinaryOperator::CreateSub(SD.SplitValue,
ConstantInt::get(Ty, 1, Sign),
"lsplit.sub", PHTerminator);
break;
ExitCondition->getOperand(ExitValueNum),
"lsplit.ev", InsertPt);
- SD.A_ExitValue = new SelectInst(C1, AEV,
- ExitCondition->getOperand(ExitValueNum),
- "lsplit.ev", InsertPt);
+ SD.A_ExitValue = SelectInst::Create(C1, AEV,
+ ExitCondition->getOperand(ExitValueNum),
+ "lsplit.ev", InsertPt);
Value *C2 = new ICmpInst(Sign ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
BSV, StartValue, "lsplit.sv",
PHTerminator);
- SD.B_StartValue = new SelectInst(C2, StartValue, BSV,
- "lsplit.sv", PHTerminator);
+ SD.B_StartValue = SelectInst::Create(C2, StartValue, BSV,
+ "lsplit.sv", PHTerminator);
}
/// splitLoop - Split current loop L in two loops using split information
BasicBlock *SplitCondBlock = SD.SplitCondition->getParent();
- // Unable to handle triange loops at the moment.
+ // Unable to handle triangle loops at the moment.
// In triangle loop, split condition is in header and one of the
// the split destination is loop latch. If split condition is EQ
// then such loops are already handle in processOneIterationLoop().
PN->addIncoming(SD.B_StartValue, A_ExitingBlock);
else {
PHINode *OrigPN = cast<PHINode>(InverseMap[PN]);
- Value *V2 = OrigPN->getIncomingValueForBlock(A_ExitingBlock);
+ Value *V2 = NULL;
+ // If loop header is also loop exiting block then
+ // OrigPN is incoming value for B loop header.
+ if (A_ExitingBlock == L->getHeader())
+ V2 = OrigPN;
+ else
+ V2 = OrigPN->getIncomingValueForBlock(A_ExitingBlock);
PN->addIncoming(V2, A_ExitingBlock);
}
} else
BI != BE; ++BI) {
if (PHINode *PN = dyn_cast<PHINode>(BI)) {
Value *V1 = PN->getIncomingValueForBlock(A_ExitBlock);
- PHINode *newPHI = new PHINode(PN->getType(), PN->getName());
+ PHINode *newPHI = PHINode::Create(PN->getType(), PN->getName());
newPHI->addIncoming(V1, A_ExitingBlock);
A_ExitBlock->getInstList().push_front(newPHI);
PN->removeIncomingValue(A_ExitBlock);
CurrentBR->eraseFromParent();
// Connect exiting block to original destination.
- new BranchInst(OrigDestBB, ExitingBB);
+ BranchInst::Create(OrigDestBB, ExitingBB);
// Update PHINodes
updatePHINodes(ExitBB, ExitingBB, CondBB, IV, IVAdd, LP);
Loop *LP) {
for (BasicBlock::iterator BI = ExitBB->begin(), BE = ExitBB->end();
- BI != BE; ++BI) {
+ BI != BE; ) {
PHINode *PN = dyn_cast<PHINode>(BI);
+ ++BI;
if (!PN)
break;
break;
}
- assert (NewV && "Unable to find new incoming value for exit block PHI");
- PN->addIncoming(NewV, Header);
+ // Add incoming value from header only if PN has any use inside the loop.
+ if (NewV)
+ PN->addIncoming(NewV, Header);
} else if (Instruction *PHI = dyn_cast<Instruction>(V)) {
// If this instruction is IVIncrement then IV is new incoming value
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