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[clang][bytecode] Allow ArrayElemPtr ops on null pointers #113132

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Merged
merged 1 commit into from
Oct 21, 2024
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[clang][bytecode] Allow ArrayElemPtr ops on null pointers #113132

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12 changes: 7 additions & 5 deletions clang/lib/AST/ByteCode/Interp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1944,14 +1944,14 @@ inline bool CastMemberPtrPtr(InterpState &S, CodePtr OpPC) {

template <class T, ArithOp Op>
bool OffsetHelper(InterpState &S, CodePtr OpPC, const T &Offset,
const Pointer &Ptr) {
const Pointer &Ptr, bool IsPointerArith = false) {
// A zero offset does not change the pointer.
if (Offset.isZero()) {
S.Stk.push<Pointer>(Ptr);
return true;
}

if (!CheckNull(S, OpPC, Ptr, CSK_ArrayIndex)) {
if (IsPointerArith && !CheckNull(S, OpPC, Ptr, CSK_ArrayIndex)) {
// The CheckNull will have emitted a note already, but we only
// abort in C++, since this is fine in C.
if (S.getLangOpts().CPlusPlus)
Expand Down Expand Up @@ -2063,14 +2063,16 @@ bool AddOffset(InterpState &S, CodePtr OpPC) {
Pointer Ptr = S.Stk.pop<Pointer>();
if (Ptr.isBlockPointer())
Ptr = Ptr.expand();
return OffsetHelper<T, ArithOp::Add>(S, OpPC, Offset, Ptr);
return OffsetHelper<T, ArithOp::Add>(S, OpPC, Offset, Ptr,
/*IsPointerArith=*/true);
}

template <PrimType Name, class T = typename PrimConv<Name>::T>
bool SubOffset(InterpState &S, CodePtr OpPC) {
const T &Offset = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.pop<Pointer>();
return OffsetHelper<T, ArithOp::Sub>(S, OpPC, Offset, Ptr);
return OffsetHelper<T, ArithOp::Sub>(S, OpPC, Offset, Ptr,
/*IsPointerArith=*/true);
}

template <ArithOp Op>
Expand All @@ -2090,7 +2092,7 @@ static inline bool IncDecPtrHelper(InterpState &S, CodePtr OpPC,

// Now the current Ptr again and a constant 1.
OneT One = OneT::from(1);
if (!OffsetHelper<OneT, Op>(S, OpPC, One, P))
if (!OffsetHelper<OneT, Op>(S, OpPC, One, P, /*IsPointerArith=*/true))
return false;

// Store the new value.
Expand Down
3 changes: 1 addition & 2 deletions clang/test/AST/ByteCode/complex.cpp
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Expand Up @@ -407,8 +407,7 @@ namespace ComplexConstexpr {
// ref-note {{cannot access real component of null}} \
// expected-note {{read of dereferenced null pointer}}
constexpr float pi = __imag *p; // both-error {{constant expr}} \
// ref-note {{cannot access imaginary component of null}} \
// expected-note {{cannot perform pointer arithmetic on null pointer}}
// ref-note {{cannot access imaginary component of null}}
constexpr const _Complex double *q = &test3 + 1;
constexpr double qr = __real *q; // ref-error {{constant expr}} \
// ref-note {{cannot access real component of pointer past the end}}
Expand Down
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