================
@@ -5001,16 +5001,76 @@ void CodeGenFunction::EmitCountedByBoundsChecking(
// Create a GEP with the byte offset between the counted object and the
// count and use that to load the count value.
- ArrayInst = Builder.CreatePointerBitCastOrAddrSpaceCast(ArrayInst,
- Int8PtrTy, Int8Ty);
+ Address CountAddr = Builder.CreatePointerBitCastOrAddrSpaceCast(
+ ArrayInst, Int8PtrTy, Int8Ty);
llvm::Type *BoundsType = ConvertType(CountFD->getType());
llvm::Value *BoundsVal =
- Builder.CreateInBoundsGEP(Int8Ty, ArrayInst.emitRawPointer(*this),
+ Builder.CreateInBoundsGEP(Int8Ty, CountAddr.emitRawPointer(*this),
Builder.getInt32(*Diff), ".counted_by.gep");
BoundsVal = Builder.CreateAlignedLoad(BoundsType, BoundsVal, getIntAlign(),
".counted_by.load");
+ const auto *CountAttributedTy =
FD->getType()->getAs<CountAttributedType>();
+ assert(CountAttributedTy && "expected FD to have a CountAttributedType");
+
+ // For the '_or_null' variants a null pointer describes no accessible
+ // memory, so treat the bound as 0 when the pointer is null; any access
then
+ // traps.
+ if (CountAttributedTy->isOrNull()) {
+ // Load the pointer from its address rather than re-emitting the
+ // member expression, which would re-evaluate a side-effecting base.
+ llvm::Value *Ptr = Builder.CreateLoad(ArrayInst);
+ llvm::Value *IsNull = Builder.CreateIsNull(Ptr);
+ BoundsVal = Builder.CreateSelect(
+ IsNull, llvm::ConstantInt::get(BoundsType, 0), BoundsVal);
+ }
+
+ // For '__sized_by' the loaded bound is a byte count. Convert it to an
+ // element count by dividing by the element size so the check can compare
+ // the (element) index directly. '__counted_by' already counts elements so
+ // needs no special handling.
+ if (CountAttributedTy->isCountInBytes()) {
+ QualType ElemTy = ArrayType->getPointeeType();
+ assert(!ElemTy.isNull() && "pointee type is never null");
+ assert(!ElemTy->isFunctionType() &&
+ "Sema guarantees a '__sized_by' pointee is a non-function type");
+ if (!ElemTy->isIncompleteType()) {
+ CharUnits ElemSize = getContext().getTypeSizeInChars(ElemTy);
+ if (ElemSize > CharUnits::One()) {
----------------
usama54321 wrote:
Can you reduce the nesting here and do early returns
https://github.com/llvm/llvm-project/pull/213795
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