r209297 - Make the parent-map use significantly less memory.

[Manuel Klimek]

On Wed, May 21, 2014 at 6:20 PM, Jordan Rose <jordan_rose at apple.com> wrote:

>
> On May 21, 2014, at 9:19 , Manuel Klimek <klimek at google.com> wrote:
>
> On Wed, May 21, 2014 at 6:10 PM, Jordan Rose <jordan_rose at apple.com>wrote:
>
>> You might want to bump up the size of the SmallVector too. Right now
>> you're dynamically allocating a SmallVector<T, 1>, and immediately putting
>> two things into it. Alternately, you could use a std::vector, which has a
>> smaller sizeof itself.
>>
>
> I tried the various combinations, and it didn't make a difference, so I
> went for making the code the simplest, which was reusing the ParentVector
> typedef.
> If we change the ParentVector to a SmallVector<T, 2> we'll also use that
> for getParents() which mostly returns a single element.
>
>
>
> SmallVector's already too big to fit in registers, so adding another two
> words to it won't really hurt any uses on the stack, will it?
>

So you're proposing to just bump it to 2? I'm happy to do that, but I lack
any way to get data that would sway me one way or the other, thus I think
it's mostly guesswork (but I trust your guesswork is probably better than
mine ;)


>
> Alternately you could wrap up your PointerUnion in something similar to
> TinyPtrVector, but that's probably more complexity than is really necessary
> here.
>
> Jordan
>
>
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