bool Changed;
public:
- static char ID; // Pass identification, replacement for typeid
- IndVarSimplify() : LoopPass(&ID) {}
-
- virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- AU.addRequired<ScalarEvolution>();
- AU.addRequiredID(LoopSimplifyID);
- AU.addRequired<LoopInfo>();
- AU.addRequired<IVUsers>();
- AU.addRequiredID(LCSSAID);
- AU.addPreserved<ScalarEvolution>();
- AU.addPreservedID(LoopSimplifyID);
- AU.addPreserved<IVUsers>();
- AU.addPreservedID(LCSSAID);
- AU.setPreservesCFG();
- }
+ static char ID; // Pass identification, replacement for typeid
+ IndVarSimplify() : LoopPass(&ID) {}
+
+ virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTree>();
+ AU.addRequired<LoopInfo>();
+ AU.addRequired<ScalarEvolution>();
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addRequiredID(LCSSAID);
+ AU.addRequired<IVUsers>();
+ AU.addPreserved<ScalarEvolution>();
+ AU.addPreservedID(LoopSimplifyID);
+ AU.addPreservedID(LCSSAID);
+ AU.addPreserved<IVUsers>();
+ AU.setPreservesCFG();
+ }
private:
<< (Opcode == ICmpInst::ICMP_NE ? "!=" : "==") << "\n"
<< " RHS:\t" << *RHS << "\n";
- ICmpInst *Cond = new ICmpInst(Opcode, CmpIndVar, ExitCnt, "exitcond", BI);
+ ICmpInst *Cond = new ICmpInst(BI, Opcode, CmpIndVar, ExitCnt, "exitcond");
Instruction *OrigCond = cast<Instruction>(BI->getCondition());
// It's tempting to use replaceAllUsesWith here to fully replace the old
// If this instruction is dead now, delete it.
RecursivelyDeleteTriviallyDeadInstructions(Inst);
- // If we're inserting code into the exit block rather than the
- // preheader, we can (and have to) remove the PHI entirely.
- // This is safe, because the NewVal won't be variant
- // in the loop, so we don't need an LCSSA phi node anymore.
- if (ExitBlocks.size() == 1) {
+ if (NumPreds == 1) {
+ // Completely replace a single-pred PHI. This is safe, because the
+ // NewVal won't be variant in the loop, so we don't need an LCSSA phi
+ // node anymore.
PN->replaceAllUsesWith(ExitVal);
RecursivelyDeleteTriviallyDeadInstructions(PN);
- break;
}
}
- if (ExitBlocks.size() != 1) {
+ if (NumPreds != 1) {
// Clone the PHI and delete the original one. This lets IVUsers and
// any other maps purge the original user from their records.
- PHINode *NewPN = PN->clone();
+ PHINode *NewPN = PN->clone(PN->getContext());
NewPN->takeName(PN);
NewPN->insertBefore(PN);
PN->replaceAllUsesWith(NewPN);
// New instructions were inserted at the end of the preheader.
if (isa<PHINode>(I))
break;
- if (I->isTrapping())
+ // Don't move instructions which might have side effects, since the side
+ // effects need to complete before instructions inside the loop. Also
+ // don't move instructions which might read memory, since the loop may
+ // modify memory. Note that it's okay if the instruction might have
+ // undefined behavior: LoopSimplify guarantees that the preheader
+ // dominates the exit block.
+ if (I->mayHaveSideEffects() || I->mayReadFromMemory())
continue;
// Determine if there is a use in or before the loop (direct or
// otherwise).
}
if (NewPred == CmpInst::BAD_ICMP_PREDICATE) return;
+ LLVMContext &Context = PH->getContext();
+
// Insert new integer induction variable.
PHINode *NewPHI = PHINode::Create(Type::Int32Ty,
PH->getName()+".int", PH);
- NewPHI->addIncoming(Context->getConstantInt(Type::Int32Ty, newInitValue),
+ NewPHI->addIncoming(Context.getConstantInt(Type::Int32Ty, newInitValue),
PH->getIncomingBlock(IncomingEdge));
Value *NewAdd = BinaryOperator::CreateAdd(NewPHI,
- Context->getConstantInt(Type::Int32Ty,
+ Context.getConstantInt(Type::Int32Ty,
newIncrValue),
Incr->getName()+".int", Incr);
NewPHI->addIncoming(NewAdd, PH->getIncomingBlock(BackEdge));
// The back edge is edge 1 of newPHI, whatever it may have been in the
// original PHI.
- ConstantInt *NewEV = Context->getConstantInt(Type::Int32Ty, intEV);
+ ConstantInt *NewEV = Context.getConstantInt(Type::Int32Ty, intEV);
Value *LHS = (EVIndex == 1 ? NewPHI->getIncomingValue(1) : NewEV);
Value *RHS = (EVIndex == 1 ? NewEV : NewPHI->getIncomingValue(1));
- ICmpInst *NewEC = new ICmpInst(NewPred, LHS, RHS, EC->getNameStart(),
- EC->getParent()->getTerminator());
+ ICmpInst *NewEC = new ICmpInst(EC->getParent()->getTerminator(),
+ NewPred, LHS, RHS, EC->getNameStart());
// In the following deltions, PH may become dead and may be deleted.
// Use a WeakVH to observe whether this happens.
RecursivelyDeleteTriviallyDeadInstructions(EC);
// Delete old, floating point, increment instruction.
- Incr->replaceAllUsesWith(Context->getUndef(Incr->getType()));
+ Incr->replaceAllUsesWith(Context.getUndef(Incr->getType()));
RecursivelyDeleteTriviallyDeadInstructions(Incr);
// Replace floating induction variable, if it isn't already deleted.