On segunda-feira, 11 de junho de 2012 16.47.46, João Abecasis wrote:
> The proposed QArrayAllocatedData is 32-bytes in size, but at the cost of two
> 4-byte padding holes. That's not that much different from a 24-byte header
> with no holes -- you can always add padding at the end ;-)
>
> With a 32
Thiago Macieira wrote:
> On segunda-feira, 11 de junho de 2012 16.00.58, João Abecasis wrote:
>> Thiago Macieira wrote:
Following Olivier's suggestion I think it might be beneficial to have
alloc
unconditionally in the base class, even if it is not being used at times.
If nothi
On segunda-feira, 11 de junho de 2012 16.16.59, João Abecasis wrote:
> > However, I don't think that's going to be a very useful use-case. I
> > already
> > think that in-place modification of externally-allocated data is a stretch
> > use- case, but one that could be eventually useful. Allowing th
Thiago Macieira wrote:
> Ok, I see. You're splitting the deleter from the immutability. Since we do
> have a flag for immutability, we can serve WebKit's use-case, but also do in-
> place modifications.
Yes.
> I find that a nice use-case.
>
> You're going further and suggesting that we could al
On segunda-feira, 11 de junho de 2012 16.00.58, João Abecasis wrote:
> Thiago Macieira wrote:
> >> Following Olivier's suggestion I think it might be beneficial to have
> >> alloc
> >> unconditionally in the base class, even if it is not being used at times.
> >> If nothing else, it saves padding.
Thiago Macieira wrote:
>> Following Olivier's suggestion I think it might be beneficial to have alloc
>> unconditionally in the base class, even if it is not being used at times.
>> If nothing else, it saves padding. Additionally, deleter function and token
>> would be more generally useful if they
On segunda-feira, 11 de junho de 2012 11.02.24, João Abecasis wrote:
> > struct Q_CORE_EXPORT QArrayData
> > {
> >
> >QtPrivate::RefCount ref;
> >uint flags;
> >int size; // ### move to the main class body?
> >// -- 4 bytes padding here on 64-bit systems --
> >qptrdiff off
On 9. juni 2012, at 17.45, ext Thiago Macieira wrote:
> Hello
>
> Moving the discussion from the series of patches I've begun on Gerrit to the
> ML.
>
> tl;dr: all I wanted was to add the prepend optimisation to QVector so I could
> work on QList. Then João told me of a request by Tor Arne ab
On sábado, 9 de junho de 2012 21.42.55, André Pönitz wrote:
> My gut feeling says there is a sweet spot at 16 byte object size,
> with direct pointer to the raw data, and size member and some
> sensible use of the extra bits.
Agreed, but it's 16 bytes on 64-bit architectures. On 32-bit ones, it wo
On Sat, Jun 09, 2012 at 05:45:01PM +0200, Thiago Macieira wrote:
> [...] - André requested that the size member be moved away from the
> header into the main class body itself. I haven't done that yet and
> I'm not sure I should. It would be major surgery for something that we
> haven't proven yet.
On sábado, 9 de junho de 2012 19.31.09, Olivier Goffart wrote:
> Then, one can put back 'alloc' in QArrayData
It's not worth it. It increases the size of the 32-bit structure and leaves us
at a weird boundary on 64-bit ones. 32 bytes is actually good.
--
Thiago Macieira - thiago.macieira (AT) int
On Saturday 09 June 2012 19:19:41 Thiago Macieira wrote:
> On sábado, 9 de junho de 2012 19.15.09, Olivier Goffart wrote:
> > I suggest re-ordering the offset in order to avoid padding.
>
> It doesn't help.
>
> > struct Q_CORE_EXPORT QArrayData
> > {
> >
> > QtPrivate::RefCount ref;
> >
On sábado, 9 de junho de 2012 19.15.09, Olivier Goffart wrote:
> I suggest re-ordering the offset in order to avoid padding.
It doesn't help.
> struct Q_CORE_EXPORT QArrayData
> {
> QtPrivate::RefCount ref;
> uint flags;
> qptrdiff offset; // in bytes from beginning of header
> in
On Saturday 09 June 2012 17:45:01 Thiago Macieira wrote:
> Hello
>
> Moving the discussion from the series of patches I've begun on Gerrit to the
> ML.
>
> tl;dr: all I wanted was to add the prepend optimisation to QVector so I
> could work on QList. Then João told me of a request by Tor Arne abo
Hello
Moving the discussion from the series of patches I've begun on Gerrit to the
ML.
tl;dr: all I wanted was to add the prepend optimisation to QVector so I could
work on QList. Then João told me of a request by Tor Arne about letting
QString have a "notify of destruction" function. So I change
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