Re: [PATCH] [POWERPC] Improve (in|out)_beXX() asm code

Andreas Schwab
2008-05-20T22:01:08Z

Trent Piepho <tpiepho@freescale.com> writes:

> For the LE versions, eventually they boil down to an asm that will look
> something like this:
> asm("sync; stwbrx %1,0,%2" : "=m" (*addr) : "r" (val), "r" (addr));
>
> While not perfect, this appears to be the best one can do. The issue is
> that the "stwbrx" instruction only comes in an indexed, or 'x', version, in
> which the address is represented by the sum of two registers (the "0,%2").
> Unfortunately, gcc doesn't have a constraint for an indexed memory
> reference.

There is the "Z" constraint, which matches either an indirect or an
indexed memory address. That should fit here.

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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