On Fri, Oct 06, 2017 at 11:45:10AM -0500, Segher Boessenkool wrote:
> Hi Mike,
>
> On Thu, Oct 05, 2017 at 06:14:14PM -0400, Michael Meissner wrote:
> > This patch adds support for most of the PowerPC ISA 3.0 Atomic Memory
> > Operation
> > instructions, listed in section 4.5 of the manual. Currently these
> > functions
> > are done via extended asm. At some point in the future, I will probably
> > move
> > the inner part of the patch to use new built-in functions to replace the
> > extended asm.
>
> Just some asm comments for now, have to think about the rest a bit more.
>
> > +#define _AMO_LD_SIMPLE(NAME, TYPE, OPCODE, FC)
> > \
> > +static __inline__ TYPE
> > \
> > +NAME (TYPE *_PTR, TYPE _VALUE)
> > \
> > +{ \
> > + unsigned __int128 _TMP; \
> > + TYPE _RET;
> > \
> > + __asm__ volatile ("mr %L1,%3\n" \
> > + "\t" OPCODE " %1,%4,%5\t\t# %0\n" \
> > + "\tmr %2,%1\n" \
> > + : "+Q" (_PTR[0]), "=&r" (_TMP), "=r" (_RET) \
> > + : "r" (_VALUE), "b" (&_PTR[0]), "n" (FC)); \
> > + return _RET;
> > \
> > +}
>
> You don't need arg 4: "%P0" is the same thing.
I didn't think there was a print_opcode that did what I wanted, I'll modify it.
> Do you really need the mr insns? Can't you express that in the
> arguments? Perhaps using a union of __int128 with something that
> is two long ints?
My first attempt resulted in the compiler doing move directs to form the
__int128 in the vector unit and then move directs back. So, I figured having
two mr's was a simple price to pay.
I do have thoughts to replace the two with a built-in (but keep amo.h and the
names), and we can probably eliminate some of the moves.
> > +#define _AMO_ST_SIMPLE(NAME, TYPE, OPCODE, FC)
> > \
> > +static __inline__ void
> > \
> > +NAME (TYPE *_PTR, TYPE _VALUE)
> > \
> > +{ \
> > + __asm__ volatile (OPCODE " %1,%2,%3\t\t# %0"
> > \
> > + : "+Q" (_PTR[0]) \
> > + : "r" (_VALUE), "b" (&_PTR[0]), "n" (FC)); \
> > + return; \
> > +}
>
> Same for "b" (arg 2) here.
>
>
> Segher
>
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: [email protected], phone: +1 (978) 899-4797
