On Tue, 28 Mar 2023 16:00:34 GMT, Thomas Stuefe <stu...@openjdk.org> wrote:
>> Please also verify against over- and underflow, and better than just null
>> checks check that every oop really is an oop. I added this to my code:
>>
>> assert((_offset <= end_offset()), "lockstack overflow: _offset %d
>> end_offset %d", _offset, end_offset());
>> assert((_offset >= start_offset()), "lockstack underflow: _offset %d
>> end_offset %d", _offset, start_offset());
>> int end = to_index(_offset);
>> for (int i = 0; i < end; i++) {
>> assert(oopDesc::is_oop(_base[i]), "index %i: not an oop (" PTR_FORMAT
>> ")", i, p2i(_base[i]));
>> ...
>
> Just realized that my proposal of oop-checking does not work since during GC
> oop can be moved and will temporarily be invalid.
Checking for is_oop() may not work, because oops may be temporarily invalid,
until the GC gets to fix them. This is especially (and probably only) true
around oops_do().
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PR Review Comment: https://git.openjdk.org/jdk/pull/10907#discussion_r1152089622
