RFR: Only verify last object start for marked objects

[Kelvin Nilsen]

On Fri, 3 Dec 2021 18:40:14 GMT, William Kemper <wkemper at openjdk.org> wrote:

> In some cases, verification could invoke `size` on an unmarked object resulting in a crash.

src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.inline.hpp line 402:

> 400:     max_offset = CardTable::card_size_in_words;
> 401:   }
> 402:   size_t prev_offset = offset;

Is this change motivated by a detected bug, or is this just a "style" improvement?  It looks to me like this change is equivalent to the original code, because in both cases (when !ctx and ctx), we unconditionally set prev_offset to offset in the first iteration of the do-while loop.

-------------

PR: https://git.openjdk.java.net/shenandoah/pull/103