}
-SSAUpdater::SSAUpdater() : AV(0), PrototypeValue(0), IPI(0) {}
+SSAUpdater::SSAUpdater(SmallVectorImpl<PHINode*> *NewPHI)
+ : AV(0), PrototypeValue(0), IPI(0), InsertedPHIs(NewPHI) {}
SSAUpdater::~SSAUpdater() {
delete &getAvailableVals(AV);
AV = new AvailableValsTy();
else
getAvailableVals(AV).clear();
-
+
if (IPI == 0)
IPI = new IncomingPredInfoTy();
else
PrototypeValue = ProtoValue;
}
+/// HasValueForBlock - Return true if the SSAUpdater already has a value for
+/// the specified block.
+bool SSAUpdater::HasValueForBlock(BasicBlock *BB) const {
+ return getAvailableVals(AV).count(BB);
+}
+
/// AddAvailableValue - Indicate that a rewritten value is available in the
/// specified block with the specified value.
void SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) {
// GetValueAtEndOfBlock to do our work.
if (!getAvailableVals(AV).count(BB))
return GetValueAtEndOfBlock(BB);
-
+
// Otherwise, we have the hard case. Get the live-in values for each
// predecessor.
SmallVector<std::pair<BasicBlock*, Value*>, 8> PredValues;
Value *SingularValue = 0;
-
+
// We can get our predecessor info by walking the pred_iterator list, but it
// is relatively slow. If we already have PHI nodes in this block, walk one
// of them to get the predecessor list instead.
BasicBlock *PredBB = SomePhi->getIncomingBlock(i);
Value *PredVal = GetValueAtEndOfBlock(PredBB);
PredValues.push_back(std::make_pair(PredBB, PredVal));
-
+
// Compute SingularValue.
if (i == 0)
SingularValue = PredVal;
BasicBlock *PredBB = *PI;
Value *PredVal = GetValueAtEndOfBlock(PredBB);
PredValues.push_back(std::make_pair(PredBB, PredVal));
-
+
// Compute SingularValue.
if (isFirstPred) {
SingularValue = PredVal;
SingularValue = 0;
}
}
-
+
// If there are no predecessors, just return undef.
if (PredValues.empty())
return UndefValue::get(PrototypeValue->getType());
-
+
// Otherwise, if all the merged values are the same, just use it.
if (SingularValue != 0)
return SingularValue;
+
+ // Otherwise, we do need a PHI: check to see if we already have one available
+ // in this block that produces the right value.
+ if (isa<PHINode>(BB->begin())) {
+ DenseMap<BasicBlock*, Value*> ValueMapping(PredValues.begin(),
+ PredValues.end());
+ PHINode *SomePHI;
+ for (BasicBlock::iterator It = BB->begin();
+ (SomePHI = dyn_cast<PHINode>(It)); ++It) {
+ // Scan this phi to see if it is what we need.
+ bool Equal = true;
+ for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i)
+ if (ValueMapping[SomePHI->getIncomingBlock(i)] !=
+ SomePHI->getIncomingValue(i)) {
+ Equal = false;
+ break;
+ }
+
+ if (Equal)
+ return SomePHI;
+ }
+ }
- // Otherwise, we do need a PHI: insert one now.
+ // Ok, we have no way out, insert a new one now.
PHINode *InsertedPHI = PHINode::Create(PrototypeValue->getType(),
PrototypeValue->getName(),
&BB->front());
InsertedPHI->reserveOperandSpace(PredValues.size());
-
+
// Fill in all the predecessors of the PHI.
for (unsigned i = 0, e = PredValues.size(); i != e; ++i)
InsertedPHI->addIncoming(PredValues[i].second, PredValues[i].first);
-
+
// See if the PHI node can be merged to a single value. This can happen in
// loop cases when we get a PHI of itself and one other value.
if (Value *ConstVal = InsertedPHI->hasConstantValue()) {
InsertedPHI->eraseFromParent();
return ConstVal;
}
- DEBUG(errs() << " Inserted PHI: " << *InsertedPHI << "\n");
+
+ // If the client wants to know about all new instructions, tell it.
+ if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
+
+ DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n");
return InsertedPHI;
}
/// which use their value in the corresponding predecessor.
void SSAUpdater::RewriteUse(Use &U) {
Instruction *User = cast<Instruction>(U.getUser());
- BasicBlock *UseBB = User->getParent();
- if (PHINode *UserPN = dyn_cast<PHINode>(User))
- UseBB = UserPN->getIncomingBlock(U);
- U.set(GetValueInMiddleOfBlock(UseBB));
+ Value *V;
+ if (PHINode *UserPN = dyn_cast<PHINode>(User))
+ V = GetValueAtEndOfBlock(UserPN->getIncomingBlock(U));
+ else
+ V = GetValueInMiddleOfBlock(User->getParent());
+
+ U.set(V);
}
///
Value *SSAUpdater::GetValueAtEndOfBlockInternal(BasicBlock *BB) {
AvailableValsTy &AvailableVals = getAvailableVals(AV);
-
+
// Query AvailableVals by doing an insertion of null.
std::pair<AvailableValsTy::iterator, bool> InsertRes =
- AvailableVals.insert(std::make_pair(BB, WeakVH()));
-
+ AvailableVals.insert(std::make_pair(BB, TrackingVH<Value>()));
+
// Handle the case when the insertion fails because we have already seen BB.
if (!InsertRes.second) {
// If the insertion failed, there are two cases. The first case is that the
// return the value.
if (InsertRes.first->second != 0)
return InsertRes.first->second;
-
+
// Otherwise, if the value we find is null, then this is the value is not
// known but it is being computed elsewhere in our recursion. This means
// that we have a cycle. Handle this by inserting a PHI node and returning
// it. When we get back to the first instance of the recursion we will fill
// in the PHI node.
return InsertRes.first->second =
- PHINode::Create(PrototypeValue->getType(), PrototypeValue->getName(),
- &BB->front());
+ PHINode::Create(PrototypeValue->getType(), PrototypeValue->getName(),
+ &BB->front());
}
-
+
// Okay, the value isn't in the map and we just inserted a null in the entry
// to indicate that we're processing the block. Since we have no idea what
// value is in this block, we have to recurse through our predecessors.
// of the recursion, just use IncomingPredInfo as an explicit stack.
IncomingPredInfoTy &IncomingPredInfo = getIncomingPredInfo(IPI);
unsigned FirstPredInfoEntry = IncomingPredInfo.size();
-
+
// As we're walking the predecessors, keep track of whether they are all
// producing the same value. If so, this value will capture it, if not, it
// will get reset to null. We distinguish the no-predecessor case explicitly
// below.
TrackingVH<Value> SingularValue;
-
+
// We can get our predecessor info by walking the pred_iterator list, but it
// is relatively slow. If we already have PHI nodes in this block, walk one
// of them to get the predecessor list instead.
BasicBlock *PredBB = SomePhi->getIncomingBlock(i);
Value *PredVal = GetValueAtEndOfBlockInternal(PredBB);
IncomingPredInfo.push_back(std::make_pair(PredBB, PredVal));
-
+
// Compute SingularValue.
if (i == 0)
SingularValue = PredVal;
BasicBlock *PredBB = *PI;
Value *PredVal = GetValueAtEndOfBlockInternal(PredBB);
IncomingPredInfo.push_back(std::make_pair(PredBB, PredVal));
-
+
// Compute SingularValue.
if (isFirstPred) {
SingularValue = PredVal;
SingularValue = 0;
}
}
-
+
// If there are no predecessors, then we must have found an unreachable block
// just return 'undef'. Since there are no predecessors, InsertRes must not
// be invalidated.
if (IncomingPredInfo.size() == FirstPredInfoEntry)
return InsertRes.first->second = UndefValue::get(PrototypeValue->getType());
-
+
/// Look up BB's entry in AvailableVals. 'InsertRes' may be invalidated. If
/// this block is involved in a loop, a no-entry PHI node will have been
/// inserted as InsertedVal. Otherwise, we'll still have the null we inserted
/// above.
TrackingVH<Value> &InsertedVal = AvailableVals[BB];
-
+
// If all the predecessor values are the same then we don't need to insert a
// PHI. This is the simple and common case.
if (SingularValue) {
} else {
InsertedVal = SingularValue;
}
-
+
+ // Either path through the 'if' should have set insertedVal -> SingularVal.
+ assert((InsertedVal == SingularValue || isa<UndefValue>(InsertedVal)) &&
+ "RAUW didn't change InsertedVal to be SingularVal");
+
// Drop the entries we added in IncomingPredInfo to restore the stack.
IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
IncomingPredInfo.end());
- return InsertedVal;
+ return SingularValue;
}
-
+
// Otherwise, we do need a PHI: insert one now if we don't already have one.
if (InsertedVal == 0)
InsertedVal = PHINode::Create(PrototypeValue->getType(),
PrototypeValue->getName(), &BB->front());
-
+
PHINode *InsertedPHI = cast<PHINode>(InsertedVal);
InsertedPHI->reserveOperandSpace(IncomingPredInfo.size()-FirstPredInfoEntry);
-
+
// Fill in all the predecessors of the PHI.
for (IncomingPredInfoTy::iterator I =
IncomingPredInfo.begin()+FirstPredInfoEntry,
E = IncomingPredInfo.end(); I != E; ++I)
InsertedPHI->addIncoming(I->second, I->first);
-
+
// Drop the entries we added in IncomingPredInfo to restore the stack.
IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
IncomingPredInfo.end());
-
+
// See if the PHI node can be merged to a single value. This can happen in
// loop cases when we get a PHI of itself and one other value.
if (Value *ConstVal = InsertedPHI->hasConstantValue()) {
InsertedPHI->eraseFromParent();
InsertedVal = ConstVal;
} else {
- DEBUG(errs() << " Inserted PHI: " << *InsertedPHI << "\n");
+ DEBUG(dbgs() << " Inserted PHI: " << *InsertedPHI << "\n");
+
+ // If the client wants to know about all new instructions, tell it.
+ if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
}
-
+
return InsertedVal;
}
-
-
projects / oota-llvm.git / blobdiff