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NFC. Introduce Value::getPointerDerferecnceableBytes

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Extract a part of isDereferenceableAndAlignedPointer functionality to Value::getPointerDerferecnceableBytes. Currently it's a NFC, but in future I'm going to accumulate all the logic about value dereferenceability in this function similarly to Value::getPointerAlignment function (D16144).

Reviewed By: reames

Differential Revision: http://reviews.llvm.org/D17572

llvm-svn: 267708
This commit is contained in:
Artur Pilipenko 2016-04-27 12:51:01 +00:00
parent 3f41257831
commit 2985d438ed
3 changed files with 43 additions and 27 deletions
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7
include/llvm/IR/Value.h
View File

@ -504,6 +504,13 @@ public:
return const_cast<Value*>(this)->stripInBoundsOffsets();
}
/// \brief Returns the number of bytes known to be dereferenceable for the
/// pointer value.
///
/// If CanBeNull is set by this function the pointer can either be null or be
/// dereferenceable up to the returned number of bytes.
unsigned getPointerDereferenceableBytes(bool &CanBeNull) const;
/// \brief Returns an alignment of the pointer value.
///
/// Returns an alignment which is either specified explicitly, e.g. via

29
lib/Analysis/Loads.cpp
View File

@ -33,34 +33,9 @@ static bool isDereferenceableFromAttribute(const Value *BV, APInt Offset,
assert(Offset.isNonNegative() && "offset can't be negative");
assert(Ty->isSized() && "must be sized");
APInt DerefBytes(Offset.getBitWidth(), 0);
bool CheckForNonNull = false;
if (const Argument *A = dyn_cast<Argument>(BV)) {
DerefBytes = A->getDereferenceableBytes();
if (!DerefBytes.getBoolValue()) {
DerefBytes = A->getDereferenceableOrNullBytes();
CheckForNonNull = true;
}
} else if (auto CS = ImmutableCallSite(BV)) {
DerefBytes = CS.getDereferenceableBytes(0);
if (!DerefBytes.getBoolValue()) {
DerefBytes = CS.getDereferenceableOrNullBytes(0);
CheckForNonNull = true;
}
} else if (const LoadInst *LI = dyn_cast<LoadInst>(BV)) {
if (MDNode *MD = LI->getMetadata(LLVMContext::MD_dereferenceable)) {
ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
DerefBytes = CI->getLimitedValue();
}
if (!DerefBytes.getBoolValue()) {
if (MDNode *MD =
LI->getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
DerefBytes = CI->getLimitedValue();
}
CheckForNonNull = true;
}
}
APInt DerefBytes(Offset.getBitWidth(),
BV->getPointerDereferenceableBytes(CheckForNonNull));
if (DerefBytes.getBoolValue())
if (DerefBytes.uge(Offset + DL.getTypeStoreSize(Ty)))

34
lib/IR/Value.cpp
View File

@ -525,6 +525,40 @@ Value *Value::stripInBoundsOffsets() {
return stripPointerCastsAndOffsets<PSK_InBounds>(this);
}
unsigned Value::getPointerDereferenceableBytes(bool &CanBeNull) const {
assert(getType()->isPointerTy() && "must be pointer");
unsigned DerefBytes = 0;
CanBeNull = false;
if (const Argument *A = dyn_cast<Argument>(this)) {
DerefBytes = A->getDereferenceableBytes();
if (DerefBytes == 0) {
DerefBytes = A->getDereferenceableOrNullBytes();
CanBeNull = true;
}
} else if (auto CS = ImmutableCallSite(this)) {
DerefBytes = CS.getDereferenceableBytes(0);
if (DerefBytes == 0) {
DerefBytes = CS.getDereferenceableOrNullBytes(0);
CanBeNull = true;
}
} else if (const LoadInst *LI = dyn_cast<LoadInst>(this)) {
if (MDNode *MD = LI->getMetadata(LLVMContext::MD_dereferenceable)) {
ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
DerefBytes = CI->getLimitedValue();
}
if (DerefBytes == 0) {
if (MDNode *MD =
LI->getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
DerefBytes = CI->getLimitedValue();
}
CanBeNull = true;
}
}
return DerefBytes;
}
unsigned Value::getPointerAlignment(const DataLayout &DL) const {
assert(getType()->isPointerTy() && "must be pointer");