bug#65491: [PATCH] Improve performance allocating vectors

[Stefan Monnier]

>> @@ -3426,6 +3428,7 @@ sweep_vectors (void)
>>    gcstat.total_vectors = 0;
>>    gcstat.total_vector_slots = gcstat.total_free_vector_slots = 0;
>>    memset (vector_free_lists, 0, sizeof (vector_free_lists));
>> +  last_known_vector_free_idx = VECTOR_MAX_FREE_LIST_INDEX;
>>  
>>    /* Looking through vector blocks.  */
>
> Hmm... so I was wrong and after GC there are aren't any free vectors?
> I need to go re-read that code, then, because it doesn't match my mental
> model of how it work(s|ed).

Ah, no, I see what's going on: the above code is run at the *beginning*
of `sweep_vectors` before we discover which (free) vectors remain.


        Stefan