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8357525: Default CDS archive becomes non-deterministic after JDK-8305895 #25373

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8357525: Default CDS archive becomes non-deterministic after JDK-8305895 #25373

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8343892: Default CDS archive becomes non-deterministic after JDK-8305895
iklam May 16, 2025
e632ac6
@shipilev comments -- fixed typo
iklam May 27, 2025
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16 changes: 12 additions & 4 deletions src/hotspot/share/oops/klass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -810,10 +810,18 @@ void Klass::remove_unshareable_info() {
set_class_loader_data(nullptr);
set_is_shared();

// FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
// Even though the bitmaps always match, the canonical order of elements in the table
// is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
//assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table");
if (CDSConfig::is_dumping_classic_static_archive()) {
// "Classic" static archives are required to have deterministic contents.
// The elements in _secondary_supers are addresses in the ArchiveBuilder
// output buffer, so they should have deterministic values. If we rehash
// _secondary_supers, its elements will appear in a deterministic order.
//
// Note that the bitmap is guaranteed to be deterministic, regardless of the
// actual addresses of the elements in _secondary_supers. So rehashing shouldn't
// change it.
uintx bitmap = hash_secondary_supers(secondary_supers(), true);
assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing");
}
}

void Klass::remove_java_mirror() {
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