Take 3: 8225716: G1 GC: Undefined behaviour in G1BlockOffsetTablePart::block_at_or_preceding

Andrew Haley aph at redhat.com
Tue Jun 18 14:48:44 UTC 2019

On 6/17/19 9:20 PM, Thomas Schatzl wrote:
>> It *might* be a (pre-existing) bug that the heap memory range
>> predicates don't accept pointer to volatile. But looking at the
>> asserts you needed to fix, my reaction is to question their utility,
>> and wonder if they should just be removed.  What do others think?
>   not seeing that they are particularly useful, so good to just remove
> to me too.


I take it, though, that we still need the check_index() in

void G1BlockOffsetTable::set_offset_array(size_t index, u_char offset) {
  check_index(index, "index out of range");
  Atomic::store(offset, &_offset_array[index]);

... and therefore we're still going to need a raw version of
set_offset_array() because zero_bottom_entry_raw() is called before the
HeapRegion is initialized, and therefore check_index() will fail.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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