[PATCH 0/5] LiveInterval refactoring

[Matthias Braun]

On Sep 3, 2013, at 11:52 AM, Benjamin Kramer <benny.kra at gmail.com> wrote:

> 
> On 03.09.2013, at 20:46, Matthias Braun <mbraun at apple.com> wrote:
> 
>> Currently I see these options:
>> 
>> 1:
>> live with a freestanding struct LiveInterval;
>> 
>> 2:
>> class LiveIntervalBase {
>> public: struct Segment {};
>> };
>> template <> struct isPodLike<LiveIntervalBase::Segment> /* … */
>> class LiveInterval : public LiveIntervalBase {
>> public:
>>   SmallVector<Segment> /* … */
>> };
>> 
>> 3:
>> /** please do not use directly but LiveInterval::Segment */
>> struct LiveSegment { /* … */ }
>> template <> struct isPodLike<LiveSegment> /* … */
>> class LiveInterval {
>> public:
>>  typedef LiveSegment Segment;
>>  SmallVector<Segment> /* … */
>> };
>> 
>> 4: Drop the isPodLike, no idea if/how badly it affects performance
> 
> When compiling with Clang we use the is_trivially_copyable type trait as a base line for isPodLike. That should be sufficient for the Segment class. Not sure if we care enough about performance on other compilers.
Indeed, sounds like a good enough reason to drop isPodLike here, IMHO.

Matthias

> 
> - Ben
> 
>> 
>> Greetings
>> 	Matthias
>> 
>> On Sep 3, 2013, at 11:39 AM, Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote:
>> 
>>> 
>>> On Sep 3, 2013, at 11:30 AM, Matthias Braun <mbraun at apple.com> wrote:
>>> 
>>>> Sounds good. Though I’m having trouble make Segment an inner class of LiveInterval:
>>>> I need to specialize the isPodLike type constraint class. But apparently c++ forces you to specialize templates at the same scope where the template was specified, so it is only possible
>>>> to do that after the LiveIntervall class, where it is too late, because the SmallVector<Segment> has already been instantiated.
>>>> So I guess I have to create a LiveSegment class outside LiveInterval, unless I’m missing some C++ tricks here…
>>> 
>>> Oh, for crying out loud! Maybe some of our C++ wizards can help?
>>> 
>>> I wonder, though, if isPodLike does any good? Could we just drop it?
>>> 
>>> Thanks,
>>> /jakob
>>> 
>> 
>> 
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