Re: NSInteger vs int vs int32_t
Re: NSInteger vs int vs int32_t
- Subject: Re: NSInteger vs int vs int32_t
- From: Kyle Sluder <email@hidden>
- Date: Mon, 02 Jul 2012 16:34:48 -0700
On Jul 2, 2012, at 4:32 PM, Jens Alfke wrote:
>
> On Jul 2, 2012, at 4:17 PM, Kyle Sluder wrote:
>
>>> It depends. 64-bit values are twice as big as 32-bit ones, so they use up twice as much L2 cache and RAM.
>>
>> I would be surprised if cache is managed at anything other than multiples of register width (64 bits).
>
> That's not the point. Data containing 64-bit values (in objects, structs, stack frames…) is obviously bigger than data containing smaller values.
Not necessarily. The CPU could just mask off the top 32 bits when executing 32-bit opcodes on in-cache data. Each 32-bit value is still taking up 64 bits of cache space. That's probably a lot easier and more efficient than making it possible to address arbitrary 32-bit slices of cache.
Note that I'm only referring to cache here, not RAM.
--Kyle Sluder
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