/// getBitWidth - Returns the bitwidth of the given scalar or pointer type (if
/// unknown returns 0). For vector types, returns the element type's bitwidth.
-static unsigned getBitWidth(const Type *Ty, const TargetData *TD) {
+static unsigned getBitWidth(Type *Ty, const TargetData *TD) {
if (unsigned BitWidth = Ty->getScalarSizeInBits())
return BitWidth;
assert(isa<PointerType>(Ty) && "Expected a pointer type!");
assert(V && "No Value?");
assert(Depth <= MaxDepth && "Limit Search Depth");
unsigned BitWidth = Mask.getBitWidth();
- assert((V->getType()->isIntOrIntVectorTy() || V->getType()->isPointerTy())
- && "Not integer or pointer type!");
+ assert((V->getType()->isIntOrIntVectorTy() ||
+ V->getType()->getScalarType()->isPointerTy()) &&
+ "Not integer or pointer type!");
assert((!TD ||
TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) &&
(!V->getType()->isIntOrIntVectorTy() ||
V->getType()->getScalarSizeInBits() == BitWidth) &&
- KnownZero.getBitWidth() == BitWidth &&
+ KnownZero.getBitWidth() == BitWidth &&
KnownOne.getBitWidth() == BitWidth &&
"V, Mask, KnownOne and KnownZero should have same BitWidth");
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
unsigned Align = GV->getAlignment();
if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) {
- const Type *ObjectType = GV->getType()->getElementType();
- // If the object is defined in the current Module, we'll be giving
- // it the preferred alignment. Otherwise, we have to assume that it
- // may only have the minimum ABI alignment.
- if (!GV->isDeclaration() && !GV->mayBeOverridden())
- Align = TD->getPrefTypeAlignment(ObjectType);
- else
- Align = TD->getABITypeAlignment(ObjectType);
+ if (GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
+ Type *ObjectType = GVar->getType()->getElementType();
+ // If the object is defined in the current Module, we'll be giving
+ // it the preferred alignment. Otherwise, we have to assume that it
+ // may only have the minimum ABI alignment.
+ if (!GVar->isDeclaration() && !GVar->isWeakForLinker())
+ Align = TD->getPreferredAlignment(GVar);
+ else
+ Align = TD->getABITypeAlignment(ObjectType);
+ }
}
if (Align > 0)
KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
}
return;
}
+
+ if (Argument *A = dyn_cast<Argument>(V)) {
+ // Get alignment information off byval arguments if specified in the IR.
+ if (A->hasByValAttr())
+ if (unsigned Align = A->getParamAlignment())
+ KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
+ CountTrailingZeros_32(Align));
+ return;
+ }
- KnownZero.clearAllBits(); KnownOne.clearAllBits(); // Start out not knowing anything.
+ // Start out not knowing anything.
+ KnownZero.clearAllBits(); KnownOne.clearAllBits();
if (Depth == MaxDepth || Mask == 0)
return; // Limit search depth.
ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero, KnownOne, TD,Depth+1);
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
- assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
- assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
-
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ bool isKnownNegative = false;
+ bool isKnownNonNegative = false;
+ // If the multiplication is known not to overflow, compute the sign bit.
+ if (Mask.isNegative() &&
+ cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap()) {
+ Value *Op1 = I->getOperand(1), *Op2 = I->getOperand(0);
+ if (Op1 == Op2) {
+ // The product of a number with itself is non-negative.
+ isKnownNonNegative = true;
+ } else {
+ bool isKnownNonNegative1 = KnownZero.isNegative();
+ bool isKnownNonNegative2 = KnownZero2.isNegative();
+ bool isKnownNegative1 = KnownOne.isNegative();
+ bool isKnownNegative2 = KnownOne2.isNegative();
+ // The product of two numbers with the same sign is non-negative.
+ isKnownNonNegative = (isKnownNegative1 && isKnownNegative2) ||
+ (isKnownNonNegative1 && isKnownNonNegative2);
+ // The product of a negative number and a non-negative number is either
+ // negative or zero.
+ if (!isKnownNonNegative)
+ isKnownNegative = (isKnownNegative1 && isKnownNonNegative2 &&
+ isKnownNonZero(Op2, TD, Depth)) ||
+ (isKnownNegative2 && isKnownNonNegative1 &&
+ isKnownNonZero(Op1, TD, Depth));
+ }
+ }
+
// If low bits are zero in either operand, output low known-0 bits.
// Also compute a conserative estimate for high known-0 bits.
// More trickiness is possible, but this is sufficient for the
KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) |
APInt::getHighBitsSet(BitWidth, LeadZ);
KnownZero &= Mask;
+
+ // Only make use of no-wrap flags if we failed to compute the sign bit
+ // directly. This matters if the multiplication always overflows, in
+ // which case we prefer to follow the result of the direct computation,
+ // though as the program is invoking undefined behaviour we can choose
+ // whatever we like here.
+ if (isKnownNonNegative && !KnownOne.isNegative())
+ KnownZero.setBit(BitWidth - 1);
+ else if (isKnownNegative && !KnownZero.isNegative())
+ KnownOne.setBit(BitWidth - 1);
+
return;
}
case Instruction::UDiv: {
// FALL THROUGH and handle them the same as zext/trunc.
case Instruction::ZExt:
case Instruction::Trunc: {
- const Type *SrcTy = I->getOperand(0)->getType();
+ Type *SrcTy = I->getOperand(0)->getType();
unsigned SrcBitWidth;
// Note that we handle pointer operands here because of inttoptr/ptrtoint
return;
}
case Instruction::BitCast: {
- const Type *SrcTy = I->getOperand(0)->getType();
+ Type *SrcTy = I->getOperand(0)->getType();
if ((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
// TODO: For now, not handling conversions like:
// (bitcast i64 %x to <2 x i32>)
KnownZero |= LHSKnownZero & Mask;
KnownOne |= LHSKnownOne & Mask;
}
+
+ // Are we still trying to solve for the sign bit?
+ if (Mask.isNegative() && !KnownZero.isNegative() && !KnownOne.isNegative()){
+ OverflowingBinaryOperator *OBO = cast<OverflowingBinaryOperator>(I);
+ if (OBO->hasNoSignedWrap()) {
+ if (I->getOpcode() == Instruction::Add) {
+ // Adding two positive numbers can't wrap into negative
+ if (LHSKnownZero.isNegative() && KnownZero2.isNegative())
+ KnownZero |= APInt::getSignBit(BitWidth);
+ // and adding two negative numbers can't wrap into positive.
+ else if (LHSKnownOne.isNegative() && KnownOne2.isNegative())
+ KnownOne |= APInt::getSignBit(BitWidth);
+ } else {
+ // Subtracting a negative number from a positive one can't wrap
+ if (LHSKnownZero.isNegative() && KnownOne2.isNegative())
+ KnownZero |= APInt::getSignBit(BitWidth);
+ // neither can subtracting a positive number from a negative one.
+ else if (LHSKnownOne.isNegative() && KnownZero2.isNegative())
+ KnownOne |= APInt::getSignBit(BitWidth);
+ }
+ }
+ }
+
return;
}
case Instruction::SRem:
gep_type_iterator GTI = gep_type_begin(I);
for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) {
Value *Index = I->getOperand(i);
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
// Handle struct member offset arithmetic.
if (!TD) return;
const StructLayout *SL = TD->getStructLayout(STy);
CountTrailingZeros_64(Offset));
} else {
// Handle array index arithmetic.
- const Type *IndexedTy = GTI.getIndexedType();
+ Type *IndexedTy = GTI.getIndexedType();
if (!IndexedTy->isSized()) return;
unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits();
uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1;
KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
break;
}
+ case Intrinsic::x86_sse42_crc32_64_8:
+ case Intrinsic::x86_sse42_crc32_64_64:
+ KnownZero = APInt::getHighBitsSet(64, 32);
+ break;
}
}
break;
/// bit set when defined. For vectors return true if every element is known to
/// be a power of two when defined. Supports values with integer or pointer
/// types and vectors of integers.
-bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, unsigned Depth) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
- return CI->getValue().isPowerOf2();
- // TODO: Handle vector constants.
+bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero,
+ unsigned Depth) {
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ if (C->isNullValue())
+ return OrZero;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
+ return CI->getValue().isPowerOf2();
+ // TODO: Handle vector constants.
+ }
// 1 << X is clearly a power of two if the one is not shifted off the end. If
// it is shifted off the end then the result is undefined.
if (Depth++ == MaxDepth)
return false;
+ Value *X = 0, *Y = 0;
+ // A shift of a power of two is a power of two or zero.
+ if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) ||
+ match(V, m_Shr(m_Value(X), m_Value()))))
+ return isPowerOfTwo(X, TD, /*OrZero*/true, Depth);
+
if (ZExtInst *ZI = dyn_cast<ZExtInst>(V))
- return isPowerOfTwo(ZI->getOperand(0), TD, Depth);
+ return isPowerOfTwo(ZI->getOperand(0), TD, OrZero, Depth);
if (SelectInst *SI = dyn_cast<SelectInst>(V))
- return isPowerOfTwo(SI->getTrueValue(), TD, Depth) &&
- isPowerOfTwo(SI->getFalseValue(), TD, Depth);
+ return isPowerOfTwo(SI->getTrueValue(), TD, OrZero, Depth) &&
+ isPowerOfTwo(SI->getFalseValue(), TD, OrZero, Depth);
+
+ if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) {
+ // A power of two and'd with anything is a power of two or zero.
+ if (isPowerOfTwo(X, TD, /*OrZero*/true, Depth) ||
+ isPowerOfTwo(Y, TD, /*OrZero*/true, Depth))
+ return true;
+ // X & (-X) is always a power of two or zero.
+ if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X))))
+ return true;
+ return false;
+ }
// An exact divide or right shift can only shift off zero bits, so the result
- // is a power of two only if the first operand is a power of two.
- if (match(V, m_Shr(m_Value(), m_Value())) ||
- match(V, m_IDiv(m_Value(), m_Value()))) {
- BinaryOperator *BO = cast<BinaryOperator>(V);
- if (BO->isExact())
- return isPowerOfTwo(BO->getOperand(0), TD, Depth);
+ // is a power of two only if the first operand is a power of two and not
+ // copying a sign bit (sdiv int_min, 2).
+ if (match(V, m_LShr(m_Value(), m_Value())) ||
+ match(V, m_UDiv(m_Value(), m_Value()))) {
+ PossiblyExactOperator *PEO = cast<PossiblyExactOperator>(V);
+ if (PEO->isExact())
+ return isPowerOfTwo(PEO->getOperand(0), TD, OrZero, Depth);
}
return false;
}
// The remaining tests are all recursive, so bail out if we hit the limit.
- if (Depth++ == MaxDepth)
+ if (Depth++ >= MaxDepth)
return false;
unsigned BitWidth = getBitWidth(V->getType(), TD);
// if the lowest bit is shifted off the end.
if (BitWidth && match(V, m_Shl(m_Value(X), m_Value(Y)))) {
// shl nuw can't remove any non-zero bits.
- BinaryOperator *BO = cast<BinaryOperator>(V);
+ OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
if (BO->hasNoUnsignedWrap())
return isKnownNonZero(X, TD, Depth);
// defined if the sign bit is shifted off the end.
else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) {
// shr exact can only shift out zero bits.
- BinaryOperator *BO = cast<BinaryOperator>(V);
+ PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
if (BO->isExact())
return isKnownNonZero(X, TD, Depth);
}
// div exact can only produce a zero if the dividend is zero.
else if (match(V, m_IDiv(m_Value(X), m_Value()))) {
- BinaryOperator *BO = cast<BinaryOperator>(V);
+ PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
if (BO->isExact())
return isKnownNonZero(X, TD, Depth);
}
}
// The sum of a non-negative number and a power of two is not zero.
- if (XKnownNonNegative && isPowerOfTwo(Y, TD, Depth))
+ if (XKnownNonNegative && isPowerOfTwo(Y, TD, /*OrZero*/false, Depth))
+ return true;
+ if (YKnownNonNegative && isPowerOfTwo(X, TD, /*OrZero*/false, Depth))
return true;
- if (YKnownNonNegative && isPowerOfTwo(X, TD, Depth))
+ }
+ // X * Y.
+ else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) {
+ OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
+ // If X and Y are non-zero then so is X * Y as long as the multiplication
+ // does not overflow.
+ if ((BO->hasNoSignedWrap() || BO->hasNoUnsignedWrap()) &&
+ isKnownNonZero(X, TD, Depth) && isKnownNonZero(Y, TD, Depth))
return true;
}
// (C ? X : Y) != 0 if X != 0 and Y != 0.
assert((TD || V->getType()->isIntOrIntVectorTy()) &&
"ComputeNumSignBits requires a TargetData object to operate "
"on non-integer values!");
- const Type *Ty = V->getType();
+ Type *Ty = V->getType();
unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) :
Ty->getScalarSizeInBits();
unsigned Tmp, Tmp2;
assert(Depth <= MaxDepth && "Limit Search Depth");
assert(V->getType()->isIntegerTy() && "Not integer or pointer type!");
- const Type *T = V->getType();
+ Type *T = V->getType();
ConstantInt *CI = dyn_cast<ConstantInt>(V);
// indices from Idxs that should be left out when inserting into the resulting
// struct. To is the result struct built so far, new insertvalue instructions
// build on that.
-static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
+static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType,
SmallVector<unsigned, 10> &Idxs,
unsigned IdxSkip,
Instruction *InsertBefore) {
- const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
+ llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
// Save the original To argument so we can modify it
Value *OrigTo = To;
break;
}
}
- // If we succesfully found a value for each of our subaggregates
+ // If we successfully found a value for each of our subaggregates
if (To)
return To;
}
// we might be able to find the complete struct somewhere.
// Find the value that is at that particular spot
- Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end());
+ Value *V = FindInsertedValue(From, Idxs);
if (!V)
return NULL;
// Insert the value in the new (sub) aggregrate
- return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip,
- Idxs.end(), "tmp", InsertBefore);
+ return llvm::InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip),
+ "tmp", InsertBefore);
}
// This helper takes a nested struct and extracts a part of it (which is again a
// insertvalue instruction somewhere).
//
// All inserted insertvalue instructions are inserted before InsertBefore
-static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
- const unsigned *idx_end,
+static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range,
Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!");
- const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
- idx_begin,
- idx_end);
+ Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
+ idx_range);
Value *To = UndefValue::get(IndexedType);
- SmallVector<unsigned, 10> Idxs(idx_begin, idx_end);
+ SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end());
unsigned IdxSkip = Idxs.size();
return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
///
/// If InsertBefore is not null, this function will duplicate (modified)
/// insertvalues when a part of a nested struct is extracted.
-Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
- const unsigned *idx_end, Instruction *InsertBefore) {
+Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range,
+ Instruction *InsertBefore) {
// Nothing to index? Just return V then (this is useful at the end of our
// recursion)
- if (idx_begin == idx_end)
+ if (idx_range.empty())
return V;
// We have indices, so V should have an indexable type
assert((V->getType()->isStructTy() || V->getType()->isArrayTy())
&& "Not looking at a struct or array?");
- assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end)
+ assert(ExtractValueInst::getIndexedType(V->getType(), idx_range)
&& "Invalid indices for type?");
- const CompositeType *PTy = cast<CompositeType>(V->getType());
+ CompositeType *PTy = cast<CompositeType>(V->getType());
if (isa<UndefValue>(V))
return UndefValue::get(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_range));
else if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_range));
else if (Constant *C = dyn_cast<Constant>(V)) {
if (isa<ConstantArray>(C) || isa<ConstantStruct>(C))
// Recursively process this constant
- return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1,
- idx_end, InsertBefore);
+ return FindInsertedValue(C->getOperand(idx_range[0]), idx_range.slice(1),
+ InsertBefore);
} else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
// Loop the indices for the insertvalue instruction in parallel with the
// requested indices
- const unsigned *req_idx = idx_begin;
+ const unsigned *req_idx = idx_range.begin();
for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
i != e; ++i, ++req_idx) {
- if (req_idx == idx_end) {
+ if (req_idx == idx_range.end()) {
if (InsertBefore)
// The requested index identifies a part of a nested aggregate. Handle
// this specially. For example,
// %C = insertvalue {i32, i32 } %A, i32 11, 1
// which allows the unused 0,0 element from the nested struct to be
// removed.
- return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore);
+ return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx),
+ InsertBefore);
else
// We can't handle this without inserting insertvalues
return 0;
// See if the (aggregrate) value inserted into has the value we are
// looking for, then.
if (*req_idx != *i)
- return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end,
+ return FindInsertedValue(I->getAggregateOperand(), idx_range,
InsertBefore);
}
// If we end up here, the indices of the insertvalue match with those
// requested (though possibly only partially). Now we recursively look at
// the inserted value, passing any remaining indices.
- return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end,
+ return FindInsertedValue(I->getInsertedValueOperand(),
+ makeArrayRef(req_idx, idx_range.end()),
InsertBefore);
} else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
// If we're extracting a value from an aggregrate that was extracted from
// However, we will need to chain I's indices with the requested indices.
// Calculate the number of indices required
- unsigned size = I->getNumIndices() + (idx_end - idx_begin);
+ unsigned size = I->getNumIndices() + idx_range.size();
// Allocate some space to put the new indices in
SmallVector<unsigned, 5> Idxs;
Idxs.reserve(size);
// Add indices from the extract value instruction
- for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
- i != e; ++i)
- Idxs.push_back(*i);
+ Idxs.append(I->idx_begin(), I->idx_end());
// Add requested indices
- for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i)
- Idxs.push_back(*i);
+ Idxs.append(idx_range.begin(), idx_range.end());
assert(Idxs.size() == size
&& "Number of indices added not correct?");
- return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
- InsertBefore);
+ return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
const TargetData &TD) {
Operator *PtrOp = dyn_cast<Operator>(Ptr);
- if (PtrOp == 0) return Ptr;
+ if (PtrOp == 0 || Ptr->getType()->isVectorTy())
+ return Ptr;
// Just look through bitcasts.
if (PtrOp->getOpcode() == Instruction::BitCast)
if (OpC->isZero()) continue;
// Handle a struct and array indices which add their offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
} else {
uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
/// null-terminated C string pointed to by V. If successful, it returns true
/// and returns the string in Str. If unsuccessful, it returns false.
bool llvm::GetConstantStringInfo(const Value *V, std::string &Str,
- uint64_t Offset,
- bool StopAtNul) {
+ uint64_t Offset, bool StopAtNul) {
// If V is NULL then return false;
if (V == NULL) return false;
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return false because ConstantArray can't occur
- // any other way
+ // any other way.
const User *GEP = 0;
if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
GEP = GEPI;
return false;
// Make sure the index-ee is a pointer to array of i8.
-
const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
-
const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
+ PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
+ ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
if (AT == 0 || !AT->getElementType()->isIntegerTy(8))
return false;
return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset,
StopAtNul);
}
-
+
// The GEP instruction, constant or instruction, must reference a global
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
return false;
const Constant *GlobalInit = GV->getInitializer();
- // Handle the ConstantAggregateZero case
- if (isa<ConstantAggregateZero>(GlobalInit)) {
+ // Handle the all-zeros case
+ if (GlobalInit->isNullValue()) {
// This is a degenerate case. The initializer is constant zero so the
// length of the string must be zero.
Str.clear();
return Len1;
}
+ // As a special-case, "@string = constant i8 0" is also a string with zero
+ // length, not wrapped in a bitcast or GEP.
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ if (GV->isConstant() && GV->hasDefinitiveInitializer())
+ if (GV->getInitializer()->isNullValue()) return 1;
+ return 0;
+ }
+
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return unknown.
User *GEP = 0;
} else {
// See if InstructionSimplify knows any relevant tricks.
if (Instruction *I = dyn_cast<Instruction>(V))
- // TODO: Aquire a DominatorTree and use it.
+ // TODO: Acquire a DominatorTree and use it.
if (Value *Simplified = SimplifyInstruction(I, TD, 0)) {
V = Simplified;
continue;
}
return V;
}
+
+/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
+/// are lifetime markers.
+///
+bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
+ for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
+ UI != UE; ++UI) {
+ const IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
+ if (!II) return false;
+
+ if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
+ II->getIntrinsicID() != Intrinsic::lifetime_end)
+ return false;
+ }
+ return true;
+}
projects / oota-llvm.git / blobdiff