Possible mark variable for force use register ?

Example C-code:
{
    register char *buf;
    long           pos;
    register int   n;
    register int   r;

    if (!n)
        return 0;
}


How to implement in D ?

On Sunday, 16 February 2020 at 13:48:43 UTC, Виталий Фадеев wrote:
> Possible mark variable for force use register ?
>
> Example C-code:
> {
>     register char *buf;
>     long           pos;
>     register int   n;
>     register int   r;
>
>     if (!n)
>         return 0;
> }
>
>
> How to implement in D ?

Don't you get a warning from your c compiler a C compiler?
The register keyword as been deprecated for ages in C.
Since the compiler cannot actually guarantee that the variable will be a register.
As a result D does not have the register keyword.

in D simply allocating a local is enough (and compiling with optimization enabled), if there is a register free to put the variable in, that's what the optimizer will do.

If you don't want to be at the mercy of the optimizer you can always write a block of asm.
Which is what I usually do when I _really_ care.

On Sunday, 16 February 2020 at 15:15:44 UTC, Stefan Koch wrote:
> The register keyword as been deprecated for ages in C.
> Since the compiler cannot actually guarantee that the variable will be a register.
> As a result D does not have the register keyword.

That only applies for C++, where it doesn't (or rather didn't) even do the same thing as in C. In C it's an optimization aid with actual semantic implications. A register storage-class variable cannot be aliased, in fact, any attempt should cause compilation failure.

Whether it actually helps modern compilers with optimization is of course another matter ;)