/// Look through operations that will be free to find the earliest source of
/// this value.
///
/// @param ValLoc If V has aggegate type, we will be interested in a particular
/// scalar component. This records its address; the reverse of this list gives a
/// sequence of indices appropriate for an extractvalue to locate the important
/// value. This value is updated during the function and on exit will indicate
/// similar information for the Value returned.
///
/// @param DataBits If this function looks through truncate instructions, this
/// will record the smallest size attained.
static const Value *getNoopInput(const Value *V,
SmallVectorImpl<unsigned> &ValLoc,
unsigned &DataBits,
const TargetLoweringBase &TLI) {
while (true) {
// Try to look through V1; if V1 is not an instruction, it can't be looked
// through.
const Instruction *I = dyn_cast<Instruction>(V);
if (!I || I->getNumOperands() == 0) return V;
const Value *NoopInput = 0;
Value *Op = I->getOperand(0);
if (isa<BitCastInst>(I)) {
// Look through truly no-op bitcasts.
if (isNoopBitcast(Op->getType(), I->getType(), TLI))
NoopInput = Op;
} else if (isa<GetElementPtrInst>(I)) {
// Look through getelementptr
if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
NoopInput = Op;
} else if (isa<IntToPtrInst>(I)) {
// Look through inttoptr.
// Make sure this isn't a truncating or extending cast. We could
// support this eventually, but don't bother for now.
if (!isa<VectorType>(I->getType()) &&
TLI.getPointerTy().getSizeInBits() ==
cast<IntegerType>(Op->getType())->getBitWidth())
NoopInput = Op;
} else if (isa<PtrToIntInst>(I)) {
// Look through ptrtoint.
// Make sure this isn't a truncating or extending cast. We could
// support this eventually, but don't bother for now.
if (!isa<VectorType>(I->getType()) &&
TLI.getPointerTy().getSizeInBits() ==
cast<IntegerType>(I->getType())->getBitWidth())
NoopInput = Op;
} else if (isa<TruncInst>(I) &&
TLI.allowTruncateForTailCall(Op->getType(), I->getType())) {
DataBits = std::min(DataBits, I->getType()->getPrimitiveSizeInBits());
NoopInput = Op;
} else if (isa<CallInst>(I)) {
// Look through call (skipping callee)
for (User::const_op_iterator i = I->op_begin(), e = I->op_end() - 1;
i != e; ++i) {
unsigned attrInd = i - I->op_begin() + 1;
if (cast<CallInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
NoopInput = *i;
break;
}
}
} else if (isa<InvokeInst>(I)) {
// Look through invoke (skipping BB, BB, Callee)
for (User::const_op_iterator i = I->op_begin(), e = I->op_end() - 3;
i != e; ++i) {
unsigned attrInd = i - I->op_begin() + 1;
if (cast<InvokeInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
NoopInput = *i;
break;
}
}
} else if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(V)) {
// Value may come from either the aggregate or the scalar
ArrayRef<unsigned> InsertLoc = IVI->getIndices();
if (std::equal(InsertLoc.rbegin(), InsertLoc.rend(),
ValLoc.rbegin())) {
// The type being inserted is a nested sub-type of the aggregate; we
// have to remove those initial indices to get the location we're
// interested in for the operand.
ValLoc.resize(ValLoc.size() - InsertLoc.size());
NoopInput = IVI->getInsertedValueOperand();
} else {
// The struct we're inserting into has the value we're interested in, no
// change of address.
NoopInput = Op;
}
} else if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
// The part we're interested in will inevitably be some sub-section of the
// previous aggregate. Combine the two paths to obtain the true address of
// our element.
ArrayRef<unsigned> ExtractLoc = EVI->getIndices();
std::copy(ExtractLoc.rbegin(), ExtractLoc.rend(),
std::back_inserter(ValLoc));
NoopInput = Op;
}
// Terminate if we couldn't find anything to look through.
if (!NoopInput)
return V;
V = NoopInput;
}
}
/// Look through operations that will be free to find the earliest source of
/// this value.
///
/// @param ValLoc If V has aggegate type, we will be interested in a particular
/// scalar component. This records its address; the reverse of this list gives a
/// sequence of indices appropriate for an extractvalue to locate the important
/// value. This value is updated during the function and on exit will indicate
/// similar information for the Value returned.
///
/// @param DataBits If this function looks through truncate instructions, this
/// will record the smallest size attained.
static const Value *getNoopInput(const Value *V,
SmallVectorImpl<unsigned> &ValLoc,
unsigned &DataBits,
const TargetLoweringBase &TLI,
const DataLayout &DL) {
while (true) {
// Try to look through V1; if V1 is not an instruction, it can't be looked
// through.
const Instruction *I = dyn_cast<Instruction>(V);
if (!I || I->getNumOperands() == 0) return V;
const Value *NoopInput = nullptr;
Value *Op = I->getOperand(0);
if (isa<BitCastInst>(I)) {
// Look through truly no-op bitcasts.
if (isNoopBitcast(Op->getType(), I->getType(), TLI))
NoopInput = Op;
} else if (isa<GetElementPtrInst>(I)) {
// Look through getelementptr
if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
NoopInput = Op;
} else if (isa<IntToPtrInst>(I)) {
// Look through inttoptr.
// Make sure this isn't a truncating or extending cast. We could
// support this eventually, but don't bother for now.
if (!isa<VectorType>(I->getType()) &&
DL.getPointerSizeInBits() ==
cast<IntegerType>(Op->getType())->getBitWidth())
NoopInput = Op;
} else if (isa<PtrToIntInst>(I)) {
// Look through ptrtoint.
// Make sure this isn't a truncating or extending cast. We could
// support this eventually, but don't bother for now.
if (!isa<VectorType>(I->getType()) &&
DL.getPointerSizeInBits() ==
cast<IntegerType>(I->getType())->getBitWidth())
NoopInput = Op;
} else if (isa<TruncInst>(I) &&
TLI.allowTruncateForTailCall(Op->getType(), I->getType())) {
DataBits = std::min(DataBits, I->getType()->getPrimitiveSizeInBits());
NoopInput = Op;
} else if (auto CS = ImmutableCallSite(I)) {
const Value *ReturnedOp = CS.getReturnedArgOperand();
if (ReturnedOp && isNoopBitcast(ReturnedOp->getType(), I->getType(), TLI))
NoopInput = ReturnedOp;
} else if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(V)) {
// Value may come from either the aggregate or the scalar
ArrayRef<unsigned> InsertLoc = IVI->getIndices();
if (ValLoc.size() >= InsertLoc.size() &&
std::equal(InsertLoc.begin(), InsertLoc.end(), ValLoc.rbegin())) {
// The type being inserted is a nested sub-type of the aggregate; we
// have to remove those initial indices to get the location we're
// interested in for the operand.
ValLoc.resize(ValLoc.size() - InsertLoc.size());
NoopInput = IVI->getInsertedValueOperand();
} else {
// The struct we're inserting into has the value we're interested in, no
// change of address.
NoopInput = Op;
}
} else if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
// The part we're interested in will inevitably be some sub-section of the
// previous aggregate. Combine the two paths to obtain the true address of
// our element.
ArrayRef<unsigned> ExtractLoc = EVI->getIndices();
ValLoc.append(ExtractLoc.rbegin(), ExtractLoc.rend());
NoopInput = Op;
}
// Terminate if we couldn't find anything to look through.
if (!NoopInput)
return V;
V = NoopInput;
}
}