Is int faster than byte/short?

[Dmitry Olshansky]

On 30.04.2011 19:34, Mariusz Gliwiński wrote:
> Hello,
> I'm trying to learn high-performance real-time programming.
>
> One of my wonderings are:
> Should i use int/uint for all standard arithmetic operations or 
> int/short/byte (depends on actual case)?
> I believe this question has following subquestions:
> * Arithmetic computations performance
> * Memory access time
>
> My actual compiler is DMD, but I'm interested in GDC as well.
>
> Lastly, one more question would be:
> Could someone recommend any books/resources for this kind of 
> informations and tips that could be applied to D? I'd like to defer my 
> own experiments with generated assembly and profiling, but i suppose 
> people already published general rules that i could apply for my 
> programming.
>
> Thanks,
> Mariusz Gliwiński
I find Agner Fog's guides on optimization for x86 the best source on 
such architecture specific matters.
http://www.agner.org/optimize/

Citing releveant part from C++ optimization guide (on Integers):
 >Integers of smaller sizes (char, short int) are only slightly less
 >efficient. In most cases, the compiler will convert these types to 
integers of the default size
 >when doing calculations, and then use only the lower 8 or 16 bits of 
the result. You can
 >assume that the type conversion takes zero or one clock cycle. In 
64-bit systems, there is
 >only a minimal difference between the efficiency of 32-bit integers 
and 64-bit integers, as
 >long as you are not doing divisions.


-- 
Dmitry Olshansky