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Pass the pointer of owning object in GCPointer::set() part I (#1502)
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Summary: Pull Request resolved: #1502

Differential Revision: D62222257
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lavenzg authored and facebook-github-bot committed Nov 23, 2024
1 parent 16d8d29 commit 2d81068
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Showing 2 changed files with 52 additions and 2 deletions.
25 changes: 25 additions & 0 deletions include/hermes/VM/GCPointer-inline.h
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,31 @@ GCPointerBase::set(PointerBase &base, CompressedPointer ptr, GC &gc) {
setNoBarrier(ptr);
}

inline void GCPointerBase::set(
PointerBase &base,
GCCell *ptr,
GC &gc,
const GCCell *owningObj) {
assert(
(!ptr || gc.validPointer(ptr)) &&
"Cannot set a GCPointer to an invalid pointer");
// Write barrier must happen before the write.
gc.writeBarrierForLargeObj(owningObj, this, ptr);
setNoBarrier(CompressedPointer::encode(ptr, base));
}

inline void GCPointerBase::setNonNull(
PointerBase &base,
GCCell *ptr,
GC &gc,
const GCCell *owningObj) {
assert(
gc.validPointer(ptr) && "Cannot set a GCPointer to an invalid pointer");
// Write barrier must happen before the write.
gc.writeBarrierForLargeObj(owningObj, this, ptr);
setNoBarrier(CompressedPointer::encodeNonNull(ptr, base));
}

inline void GCPointerBase::setNull(GC &gc) {
gc.snapshotWriteBarrier(this);
setNoBarrier(CompressedPointer(nullptr));
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29 changes: 27 additions & 2 deletions include/hermes/VM/GCPointer.h
Original file line number Diff line number Diff line change
Expand Up @@ -34,14 +34,26 @@ class GCPointerBase : public CompressedPointer {
class NoBarriers : public std::false_type {};
class YesBarriers : public std::true_type {};

/// This must be used to assign a new value to this GCPointer.
/// This must be used to assign a new value to this GCPointer. This must not
/// be used if it lives in an object that supports large allocation.
/// \param ptr The memory being pointed to.
/// \param base The base of ptr.
/// \param gc Used for write barriers.
inline void set(PointerBase &base, GCCell *ptr, GC &gc);
inline void set(PointerBase &base, CompressedPointer ptr, GC &gc);
inline void setNonNull(PointerBase &base, GCCell *ptr, GC &gc);

/// This must be used to assign a new value to this GCPointer.
/// \param ptr The memory being pointed to.
/// \param base The base of ptr.
/// \param gc Used for write barriers.
/// \param owningObj The object that contains this GCPointer, used by the
/// writer barriers.
inline void
set(PointerBase &base, GCCell *ptr, GC &gc, const GCCell *owningObj);
inline void
setNonNull(PointerBase &base, GCCell *ptr, GC &gc, const GCCell *owningObj);

/// Set this pointer to null. This needs a write barrier in some types of
/// garbage collectors.
inline void setNull(GC &gc);
Expand Down Expand Up @@ -86,7 +98,8 @@ class GCPointer : public GCPointerBase {
return vmcast<T>(GCPointerBase::getNonNull(base));
}

/// Assign a new value to this GCPointer.
/// Assign a new value to this GCPointer. This must not be used if it lives in
/// an object that supports large allocation.
/// \param base The base of ptr.
/// \param ptr The memory being pointed to.
/// \param gc Used for write barriers.
Expand All @@ -97,6 +110,18 @@ class GCPointer : public GCPointerBase {
GCPointerBase::setNonNull(base, ptr, gc);
}

/// Assign a new value to this GCPointer.
/// \param ptr The memory being pointed to.
/// \param gc Used for write barriers.
/// \param owningObj The object that contains this GCPointer, used by the
/// writer barriers.
void set(PointerBase &base, T *ptr, GC &gc, const GCCell *owningObj) {
GCPointerBase::set(base, ptr, gc, owningObj);
}
void setNonNull(PointerBase &base, T *ptr, GC &gc, const GCCell *owningObj) {
GCPointerBase::setNonNull(base, ptr, gc, owningObj);
}

/// Convenience overload of GCPointer::set for other GCPointers.
void set(PointerBase &base, const GCPointer<T> &ptr, GC &gc) {
GCPointerBase::set(base, ptr, gc);
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