The alignment size of the type "real" is smaller than it's size.

real.sizeof: 10
real.alignof: 2

Maybe I don't get the point of ".alignof".
Shouldn't it be at least ".sizeof"?

system: Linux / i686

Thomas

Thomas Kuehne wrote:
> The alignment size of the type "real" is smaller than it's size.
> 
> real.sizeof: 10
> real.alignof: 2
> 
> Maybe I don't get the point of ".alignof".
> Shouldn't it be at least ".sizeof"?

Thinking about 32bit machines for a moment...real requires 3 reads or writes, so long as it is aligned to a 2 byte boundary.  Aligning it to a 4 byte boundary (or even more) doesn't gain you anything.  You just don't want to hit an odd address, since then you might require 4 accesses.

On the other hand, you might be bad performance if a real crosses a cache line boundary...perhaps that is an argument for real.alignof=16 ?