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[clang][bytecode] Call CheckStore() before activating pointers #165235

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Merged
tbaederr merged 1 commit into from
Oct 27, 2025
Merged

[clang][bytecode] Call CheckStore() before activating pointers #165235

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5 changes: 3 additions & 2 deletions clang/lib/AST/ByteCode/Interp.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -870,7 +870,8 @@ bool CheckFinalLoad(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
return true;
}

bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
bool WillBeActivated) {
if (!Ptr.isBlockPointer() || Ptr.isZero())
return false;

Expand All @@ -885,7 +886,7 @@ bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
return false;
if (!CheckRange(S, OpPC, Ptr, AK_Assign))
return false;
if (!CheckActive(S, OpPC, Ptr, AK_Assign))
if (!WillBeActivated && !CheckActive(S, OpPC, Ptr, AK_Assign))
return false;
if (!CheckGlobal(S, OpPC, Ptr))
return false;
Expand Down
24 changes: 13 additions & 11 deletions clang/lib/AST/ByteCode/Interp.h
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Expand Up @@ -75,7 +75,8 @@ bool CheckGlobalLoad(InterpState &S, CodePtr OpPC, const Block *B);
bool CheckLocalLoad(InterpState &S, CodePtr OpPC, const Block *B);

/// Checks if a value can be stored in a block.
bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
bool WillBeActivated = false);

/// Checks if a value can be initialized.
bool CheckInit(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
Expand Down Expand Up @@ -1977,13 +1978,12 @@ bool StoreActivate(InterpState &S, CodePtr OpPC) {
const T &Value = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.peek<Pointer>();

if (!CheckStore(S, OpPC, Ptr, /*WilLBeActivated=*/true))
return false;
if (Ptr.canBeInitialized()) {
Ptr.initialize();
Ptr.activate();
}

if (!CheckStore(S, OpPC, Ptr))
return false;
Ptr.deref<T>() = Value;
return true;
}
Expand All @@ -1993,12 +1993,12 @@ bool StoreActivatePop(InterpState &S, CodePtr OpPC) {
const T &Value = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.pop<Pointer>();

if (!CheckStore(S, OpPC, Ptr, /*WilLBeActivated=*/true))
return false;
if (Ptr.canBeInitialized()) {
Ptr.initialize();
Ptr.activate();
}
if (!CheckStore(S, OpPC, Ptr))
return false;
Ptr.deref<T>() = Value;
return true;
}
Expand All @@ -2007,7 +2007,8 @@ template <PrimType Name, class T = typename PrimConv<Name>::T>
bool StoreBitField(InterpState &S, CodePtr OpPC) {
const T &Value = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.peek<Pointer>();
if (!CheckStore(S, OpPC, Ptr))

if (!CheckStore(S, OpPC, Ptr, /*WilLBeActivated=*/true))
return false;
if (Ptr.canBeInitialized())
Ptr.initialize();
Expand Down Expand Up @@ -2037,12 +2038,13 @@ template <PrimType Name, class T = typename PrimConv<Name>::T>
bool StoreBitFieldActivate(InterpState &S, CodePtr OpPC) {
const T &Value = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.peek<Pointer>();

if (!CheckStore(S, OpPC, Ptr, /*WilLBeActivated=*/true))
return false;
if (Ptr.canBeInitialized()) {
Ptr.initialize();
Ptr.activate();
}
if (!CheckStore(S, OpPC, Ptr))
return false;
if (const auto *FD = Ptr.getField())
Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue());
else
Expand All @@ -2055,12 +2057,12 @@ bool StoreBitFieldActivatePop(InterpState &S, CodePtr OpPC) {
const T &Value = S.Stk.pop<T>();
const Pointer &Ptr = S.Stk.pop<Pointer>();

if (!CheckStore(S, OpPC, Ptr, /*WillBeActivated=*/true))
return false;
if (Ptr.canBeInitialized()) {
Ptr.initialize();
Ptr.activate();
}
if (!CheckStore(S, OpPC, Ptr))
return false;
if (const auto *FD = Ptr.getField())
Ptr.deref<T>() = Value.truncate(FD->getBitWidthValue());
else
Expand Down
9 changes: 9 additions & 0 deletions clang/test/AST/ByteCode/unions.cpp
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Expand Up @@ -977,4 +977,13 @@ namespace UnionMemberOnePastEnd {
}
static_assert(!b());
}

namespace ActicvateInvalidPtr {
constexpr void bar() { // both-error {{never produces a constant expression}}
union {
int a[1];
} foo;
foo.a[1] = 0; // both-note {{assignment to dereferenced one-past-the-end pointer}}
}
}
#endif