Memory corruption with -O3, but not -O2 (and not with DMD)

[Kagamin]

On Saturday, 17 August 2019 at 20:33:08 UTC, James Blachly wrote:
> Am at my wits' end, so help or next steps are greatly 
> appreciated. I can provide disassembly of whatever combination 
> of -O/-O2/-O3 and triggering/nontriggering code blocks if it 
> would e helpful.

Did you check that only this block is responsible for it? Compile 
all code with -O2 and only this particular block with -O3 and see 
if it still happens.