Re: master 9227864: Further fix for aborts due to GC losing pseudovectors

[Paul Eggert]

On 5/26/20 12:25 AM, Pip Cet wrote:

> Then we shouldn't mention any system at all.

No big deal either way. I thought it helpful to give an example.

> roundup_size still uses LISP_ALIGNMENT here, so I don't see how that's
> true.

Oh, you're right. No harm so far since LISP_ALIGNMENT is 8 on current platforms.
But this area could use some thinking if we want more efficiency on platforms
where it's 16 (so far, I've been worried only about avoiding crashes on such
machines).
>>> I think a simple eassert (GCALIGNMENT % alignof (type) == 0) in an
>>> (inlined, obviously) version of allocate_pseudovector should suffice
>>> to catch this hypothetical problem.
>>
>> I assume you meant 'verify' rather than 'eassert'? That'd catch the bug at
>> compile time.
> 
> I don't see how that would be possible using inline functions?

We should use macros, as they'll catch this at compile-time. (I don't know how
to do an eassert_reachable.) We're already using macros for
ALLOCATE_PSEUDOVECTOR and the like, so this should not be a big deal.