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

[Kim Barrett]

> On Jun 17, 2019, at 11:35 AM, Andrew Haley <aph at redhat.com> wrote:
> 
> On 6/13/19 6:26 PM, Kim Barrett wrote:
> 
>> set_offset_array_raw looks quite uninterestingly different from
>> set_offset_array (whose definition is in the .inline.hpp, near the
>> definition of offset_array that needed to be changed). Consider
>> hoisting set_offset_array_raw into set_offset_array, killing off the
>> _raw function, and updating the one remaining caller.
> 
> Previous patch failed testing. We really do need
> set_offset_array_raw(), not for efficiency but because at the very
> start the assert invariants do not hold.
> 
> In this version of the patch set_offset_array_raw() is back and I had
> to add a couple more const_casts in assertions. Fingers crossed.
> 
> http://cr.openjdk.java.net/~aph/8225716-3/

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?