================
@@ -358,49 +360,59 @@ UseCaptureKind llvm::DetermineUseCaptureKind(
// Volatile stores make the address observable.
auto *ACXI = cast<AtomicCmpXchgInst>(I);
if (U.getOperandNo() == 1 || U.getOperandNo() == 2 || ACXI->isVolatile())
- return UseCaptureKind::MAY_CAPTURE;
- return UseCaptureKind::NO_CAPTURE;
+ return CaptureInfo::otherOnly();
+ return CaptureInfo::none();
}
case Instruction::GetElementPtr:
// AA does not support pointers of vectors, so GEP vector splats need to
// be considered as captures.
if (I->getType()->isVectorTy())
- return UseCaptureKind::MAY_CAPTURE;
- return UseCaptureKind::PASSTHROUGH;
+ return CaptureInfo::otherOnly();
+ return CaptureInfo::retOnly();
case Instruction::BitCast:
case Instruction::PHI:
case Instruction::Select:
case Instruction::AddrSpaceCast:
// The original value is not captured via this if the new value isn't.
- return UseCaptureKind::PASSTHROUGH;
+ return CaptureInfo::retOnly();
case Instruction::ICmp: {
unsigned Idx = U.getOperandNo();
unsigned OtherIdx = 1 - Idx;
- if (auto *CPN = dyn_cast<ConstantPointerNull>(I->getOperand(OtherIdx))) {
+ if (isa<ConstantPointerNull>(I->getOperand(OtherIdx)) &&
+ cast<ICmpInst>(I)->isEquality()) {
+ // TODO(captures): Remove these special cases once we make use of
+ // captures(address_is_null).
+
// Don't count comparisons of a no-alias return value against null as
// captures. This allows us to ignore comparisons of malloc results
// with null, for example.
- if (CPN->getType()->getAddressSpace() == 0)
+ if (U->getType()->getPointerAddressSpace() == 0)
if (isNoAliasCall(U.get()->stripPointerCasts()))
- return UseCaptureKind::NO_CAPTURE;
+ return CaptureInfo::none();
if (!I->getFunction()->nullPointerIsDefined()) {
auto *O = I->getOperand(Idx)->stripPointerCastsSameRepresentation();
// Comparing a dereferenceable_or_null pointer against null cannot
// lead to pointer escapes, because if it is not null it must be a
// valid (in-bounds) pointer.
const DataLayout &DL = I->getDataLayout();
if (IsDereferenceableOrNull && IsDereferenceableOrNull(O, DL))
- return UseCaptureKind::NO_CAPTURE;
+ return CaptureInfo::none();
}
+
+ // Check whether this is a comparison of the base pointer against
+ // null.
+ if (U.get() == Base)
+ return CaptureInfo::otherOnly(CaptureComponents::AddressIsNull);
}
// Otherwise, be conservative. There are crazy ways to capture pointers
- // using comparisons.
- return UseCaptureKind::MAY_CAPTURE;
+ // using comparisons. However, only the address is captured, not the
+ // provenance.
+ return CaptureInfo::otherOnly(CaptureComponents::Address);
----------------
goldsteinn wrote:
Why here (and above) is the `otherOnly`? If the result is used by a `ret` is it
not potentially both?
Maybe I misunderstand the refinement process.
https://github.com/llvm/llvm-project/pull/125880
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