Passing pointers as function parameters

[Kempelen]

Hello,

Good C programming practices talk about passing variables as parameters to function opposite to global vars. I have seen in my own programs this is a good practice as the compiler optimize those variables very well.

Now I have a problem. My new program uses a vector of very large structs. I have noted I can not pass the complete struct as a parameter as it takes many time to copy the structure, so the only plausible way to do it is passing a pointer to the struct I am going to modify.

So far is ok, but I have doubts about the way the compiler optimize the struct access thought the pointer. I have hear of aliasing been a optimization problem when using pointers, but I have not clue what this mean. My program is not multithread so I am sure there is only single access to variables, but I know the compiler does not know that and it does not optimize this kind of access the same way as it would ve a parameter variable of the function.

I admit I am completely stupid in how the compiler works, about all when working with pointer, so my question is what must I have take into account in order to point the compiler to optimize in the best way the access to the struct thought pointers?, is there guidelines on how can I take the best optimization of them? must I instruct the compiler (via options or via programming) to best optimize?

thx

[Bayint Naung]

Demystifying The Restrict Keyword - CellPerformance

[Kempelen]

struct foo
{ } myarrayoffoo[ SOMEFOOSIZE ];
...

void somefun( struct foo *yay )
{
}

...

somefun( myarrayoffoo );

Quzah.

Dont understand what you are trying to say me.
In my program, following your example I call a function like: somefun(&myarrayofffoo[48])
I mean, I pass only a concrete pointer to a record, and the complete struct.
What I like is to know how the compiler use pointer inside the function and if there are ways to optimize it as it would be a local var (or similar)

[quzah]

I completely misread what you were trying to ask.

Quzah.