/// getFeasibleSuccessors - Return a vector of booleans to indicate which
/// successors are reachable from a given terminator instruction.
void SparseSolver::getFeasibleSuccessors(TerminatorInst &TI,
SmallVectorImpl<bool> &Succs,
bool AggressiveUndef) {
Succs.resize(TI.getNumSuccessors());
if (TI.getNumSuccessors() == 0) return;
if (BranchInst *BI = dyn_cast<BranchInst>(&TI)) {
if (BI->isUnconditional()) {
Succs[0] = true;
return;
}
LatticeVal BCValue;
if (AggressiveUndef)
BCValue = getOrInitValueState(BI->getCondition());
else
BCValue = getLatticeState(BI->getCondition());
if (BCValue == LatticeFunc->getOverdefinedVal() ||
BCValue == LatticeFunc->getUntrackedVal()) {
// Overdefined condition variables can branch either way.
Succs[0] = Succs[1] = true;
return;
}
// If undefined, neither is feasible yet.
if (BCValue == LatticeFunc->getUndefVal())
return;
Constant *C = LatticeFunc->GetConstant(BCValue, BI->getCondition(), *this);
if (C == 0 || !isa<ConstantInt>(C)) {
// Non-constant values can go either way.
Succs[0] = Succs[1] = true;
return;
}
// Constant condition variables mean the branch can only go a single way
Succs[C->isNullValue()] = true;
return;
}
if (isa<InvokeInst>(TI)) {
// Invoke instructions successors are always executable.
// TODO: Could ask the lattice function if the value can throw.
Succs[0] = Succs[1] = true;
return;
}
if (isa<IndirectBrInst>(TI)) {
Succs.assign(Succs.size(), true);
return;
}
SwitchInst &SI = cast<SwitchInst>(TI);
LatticeVal SCValue;
if (AggressiveUndef)
SCValue = getOrInitValueState(SI.getCondition());
else
SCValue = getLatticeState(SI.getCondition());
if (SCValue == LatticeFunc->getOverdefinedVal() ||
SCValue == LatticeFunc->getUntrackedVal()) {
// All destinations are executable!
Succs.assign(TI.getNumSuccessors(), true);
return;
}
// If undefined, neither is feasible yet.
if (SCValue == LatticeFunc->getUndefVal())
return;
Constant *C = LatticeFunc->GetConstant(SCValue, SI.getCondition(), *this);
if (C == 0 || !isa<ConstantInt>(C)) {
// All destinations are executable!
Succs.assign(TI.getNumSuccessors(), true);
return;
}
SwitchInst::CaseIt Case = SI.findCaseValue(cast<ConstantInt>(C));
Succs[Case.getSuccessorIndex()] = true;
}
unsigned ConstraintGraph::computeConnectedComponents(
SmallVectorImpl<TypeVariableType *> &typeVars,
SmallVectorImpl<unsigned> &components) {
// Track those type variables that the caller cares about.
llvm::SmallPtrSet<TypeVariableType *, 4> typeVarSubset(typeVars.begin(),
typeVars.end());
typeVars.clear();
// Initialize the components with component == # of type variables,
// a sentinel value indicating
unsigned numTypeVariables = TypeVariables.size();
components.assign(numTypeVariables, numTypeVariables);
// Perform a depth-first search from each type variable to identify
// what component it is in.
unsigned numComponents = 0;
for (unsigned i = 0; i != numTypeVariables; ++i) {
auto typeVar = TypeVariables[i];
// Look up the node for this type variable.
auto nodeAndIndex = lookupNode(typeVar);
// If we're already assigned a component for this node, skip it.
unsigned &curComponent = components[nodeAndIndex.second];
if (curComponent != numTypeVariables)
continue;
// Record this component.
unsigned component = numComponents++;
// Note that this node is part of this component, then visit it.
curComponent = component;
connectedComponentsDFS(*this, nodeAndIndex.first, component, components);
}
// Figure out which components have unbound type variables; these
// are the only components and type variables we want to report.
SmallVector<bool, 4> componentHasUnboundTypeVar(numComponents, false);
for (unsigned i = 0; i != numTypeVariables; ++i) {
// If this type variable has a fixed type, skip it.
if (CS.getFixedType(TypeVariables[i]))
continue;
// If we only care about a subset, and this type variable isn't in that
// subset, skip it.
if (!typeVarSubset.empty() && typeVarSubset.count(TypeVariables[i]) == 0)
continue;
componentHasUnboundTypeVar[components[i]] = true;
}
// Renumber the old components to the new components.
SmallVector<unsigned, 4> componentRenumbering(numComponents, 0);
numComponents = 0;
for (unsigned i = 0, n = componentHasUnboundTypeVar.size(); i != n; ++i) {
// Skip components that have no unbound type variables.
if (!componentHasUnboundTypeVar[i])
continue;
componentRenumbering[i] = numComponents++;
}
// Copy over the type variables in the live components and remap
// component numbers.
unsigned outIndex = 0;
for (unsigned i = 0, n = TypeVariables.size(); i != n; ++i) {
// Skip type variables in dead components.
if (!componentHasUnboundTypeVar[components[i]])
continue;
typeVars.push_back(TypeVariables[i]);
components[outIndex] = componentRenumbering[components[i]];
++outIndex;
}
components.erase(components.begin() + outIndex, components.end());
return numComponents;
}
/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
/// elements from either LHS or RHS, return the shuffle mask and true.
/// Otherwise, return false.
static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
SmallVectorImpl<Constant*> &Mask) {
assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
"Invalid CollectSingleShuffleElements");
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
if (isa<UndefValue>(V)) {
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
return true;
}
if (V == LHS) {
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
return true;
}
if (V == RHS) {
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()),
i+NumElts));
return true;
}
if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
// If this is an insert of an extract from some other vector, include it.
Value *VecOp = IEI->getOperand(0);
Value *ScalarOp = IEI->getOperand(1);
Value *IdxOp = IEI->getOperand(2);
if (!isa<ConstantInt>(IdxOp))
return false;
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
// Okay, we can handle this if the vector we are insertinting into is
// transitively ok.
if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
// If so, update the mask to reflect the inserted undef.
Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(V->getContext()));
return true;
}
} else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
if (isa<ConstantInt>(EI->getOperand(1)) &&
EI->getOperand(0)->getType() == V->getType()) {
unsigned ExtractedIdx =
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
// This must be extracting from either LHS or RHS.
if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
// Okay, we can handle this if the vector we are insertinting into is
// transitively ok.
if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
// If so, update the mask to reflect the inserted value.
if (EI->getOperand(0) == LHS) {
Mask[InsertedIdx % NumElts] =
ConstantInt::get(Type::getInt32Ty(V->getContext()),
ExtractedIdx);
} else {
assert(EI->getOperand(0) == RHS);
Mask[InsertedIdx % NumElts] =
ConstantInt::get(Type::getInt32Ty(V->getContext()),
ExtractedIdx+NumElts);
}
return true;
}
}
}
}
}
// TODO: Handle shufflevector here!
return false;
}
static ShuffleOps CollectShuffleElements(Value *V,
SmallVectorImpl<Constant *> &Mask,
Value *PermittedRHS) {
assert(V->getType()->isVectorTy() && "Invalid shuffle!");
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
if (isa<UndefValue>(V)) {
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
return std::make_pair(
PermittedRHS ? UndefValue::get(PermittedRHS->getType()) : V, nullptr);
}
if (isa<ConstantAggregateZero>(V)) {
Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
return std::make_pair(V, nullptr);
}
if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
// If this is an insert of an extract from some other vector, include it.
Value *VecOp = IEI->getOperand(0);
Value *ScalarOp = IEI->getOperand(1);
Value *IdxOp = IEI->getOperand(2);
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp)) {
unsigned ExtractedIdx =
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
// Either the extracted from or inserted into vector must be RHSVec,
// otherwise we'd end up with a shuffle of three inputs.
if (EI->getOperand(0) == PermittedRHS || PermittedRHS == nullptr) {
Value *RHS = EI->getOperand(0);
ShuffleOps LR = CollectShuffleElements(VecOp, Mask, RHS);
assert(LR.second == nullptr || LR.second == RHS);
if (LR.first->getType() != RHS->getType()) {
// We tried our best, but we can't find anything compatible with RHS
// further up the chain. Return a trivial shuffle.
for (unsigned i = 0; i < NumElts; ++i)
Mask[i] = ConstantInt::get(Type::getInt32Ty(V->getContext()), i);
return std::make_pair(V, nullptr);
}
unsigned NumLHSElts = RHS->getType()->getVectorNumElements();
Mask[InsertedIdx % NumElts] =
ConstantInt::get(Type::getInt32Ty(V->getContext()),
NumLHSElts+ExtractedIdx);
return std::make_pair(LR.first, RHS);
}
if (VecOp == PermittedRHS) {
// We've gone as far as we can: anything on the other side of the
// extractelement will already have been converted into a shuffle.
unsigned NumLHSElts =
EI->getOperand(0)->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(
Type::getInt32Ty(V->getContext()),
i == InsertedIdx ? ExtractedIdx : NumLHSElts + i));
return std::make_pair(EI->getOperand(0), PermittedRHS);
}
// If this insertelement is a chain that comes from exactly these two
// vectors, return the vector and the effective shuffle.
if (EI->getOperand(0)->getType() == PermittedRHS->getType() &&
CollectSingleShuffleElements(IEI, EI->getOperand(0), PermittedRHS,
Mask))
return std::make_pair(EI->getOperand(0), PermittedRHS);
}
}
}
// Otherwise, can't do anything fancy. Return an identity vector.
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
return std::make_pair(V, nullptr);
}
