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[vm] Handle non-Smi lengths during heap snapshot writing.

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This applies to List/Map/Set, which have logical lengths that are initialized by Dart constructors. It does not apply to Array/String/TypedData, which have physical lengths that must always be initialized before the next safepoint.

TEST=ci
Bug: https://github.com/dart-lang/sdk/issues/55689
Change-Id: If132405249e4e49920b0f4f63f85ebeb49e23671
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/400020
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This commit is contained in:
Ryan Macnak
2024-12-10 21:48:58 +00:00
committed by Commit Queue
parent 2d7bb5d052
commit 487c595758
1 changed files with 10 additions and 3 deletions
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runtime/vm/object_graph.cc
+10 -3
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@@ -1120,6 +1120,13 @@ class Pass2Visitor : public ObjectVisitor,
writer_(writer),
object_slots_(object_slots) {}
// A safepoint might occur between the allocation stub creating an object and
// filling it with nulls and the instance initializer running and populating a
// length field.
static intptr_t SmiValueOrZero(SmiPtr smi) {
return smi->IsSmi() ? Smi::Value(smi) : 0;
}
void VisitObject(ObjectPtr obj) override {
if (obj->IsPseudoObject()) return;
@@ -1171,16 +1178,16 @@ class Pass2Visitor : public ObjectVisitor,
Smi::Value(static_cast<ArrayPtr>(obj)->untag()->length()));
} else if (cid == kGrowableObjectArrayCid) {
writer_->WriteUnsigned(kLengthData);
writer_->WriteUnsigned(Smi::Value(
writer_->WriteUnsigned(SmiValueOrZero(
static_cast<GrowableObjectArrayPtr>(obj)->untag()->length()));
} else if (cid == kMapCid || cid == kConstMapCid) {
writer_->WriteUnsigned(kLengthData);
writer_->WriteUnsigned(
Smi::Value(static_cast<MapPtr>(obj)->untag()->used_data()));
SmiValueOrZero(static_cast<MapPtr>(obj)->untag()->used_data()));
} else if (cid == kSetCid || cid == kConstSetCid) {
writer_->WriteUnsigned(kLengthData);
writer_->WriteUnsigned(
Smi::Value(static_cast<SetPtr>(obj)->untag()->used_data()));
SmiValueOrZero(static_cast<SetPtr>(obj)->untag()->used_data()));
} else if (cid == kObjectPoolCid) {
writer_->WriteUnsigned(kLengthData);
writer_->WriteUnsigned(static_cast<ObjectPoolPtr>(obj)->untag()->length_);