Josef Ahmad <josef_ahm@xxxxxxxxx> writes:
> I would appreciate if somebody knows whether there is a way to specify, through the gcc extended inline assembly construct, a precise kind of registers.
> To be more specific, I would like to indicate that the given instruction operand must be a SPARC output register.
>
> e.g.
>
> int var;
> asm volatile("instructionname %1"
> : /* no output */
> : "xxx"(var)
> : /* no clobbered regs */
> );
>
> In this case, I would like to find, if existing, the right constraint to use instead of xxx to ask the compiler to pick one of the o0 - o7 registers.
>
> I state beforehand that I have read the related gcc documentation, unfortunately without finding anything related to my question. I think that gcc focuses strictly on the SPARC ABI compliance rather than allowing a wide range of customization to the inline assembly, but I hope I am wrong and there is a possibility to do this trick.
Use asm ("REGNAME") with var, e.g.,
int var asm ("%o0");
Then use a constraint which permits %o0, such as simply "r".
Ian
