RE: memory alignment vs passing by value

"Jon Watte" <[email protected]> Wed, 1 Dec 2004 18:07:47 -0800
Newsgroups gmane.games.devel.windows
Message-ID <[email protected]>
> It seems weird that aliasing would be a problem - since everything is in 
> 4 bytes chunks. From what I understood about aliasing, that only 
> mattered if you broke dword alignment, e.g.

That's CPU register and memory aliasing, which is not the kind of 
aliasing I'm talking about. In compilers, any access through a 
pointer might conceivably change the value of the pointer itself 
(for example), so each time the pointer is accessed, it has to be 
re-loaded. There are type-based proofs the compiler can execute 
to not have to do this all the time, but most compilers are quite 
conservative. A simple disassembly of the two cases should tell 
you whether this is the case.

Cheers,

			/ h+



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