• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (11/11) Feb 16 2020 Possible mark variable for force use register ?
• Stefan Koch (12/23) Feb 16 2020 Don't you get a warning from your c compiler a C compiler?
• lithium iodate (8/12) Feb 16 2020 That only applies for C++, where it doesn't (or rather didn't)

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

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 ?

Stefan Koch <uplink.coder googlemail.com> writes:

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.

lithium iodate <whatdoiknow doesntexist.net> writes:

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 ;)