On Tue, Jan 09, 2024 at 04:35:22PM -0600, Peter Bergner wrote:
> On 1/5/24 4:18 PM, Michael Meissner wrote:
> > @@ -14504,13 +14504,17 @@ print_operand (FILE *file, rtx x, int code)
> > print_operand (file, x, 0);
> > return;
> >
> > + case 'S':
> > case 'x':
> > - /* X is a FPR or Altivec register used in a VSX context. */
> > + /* X is a FPR or Altivec register used in a VSX context. %x<n>
> > prints
> > + the VSX register number, %S<n> prints the 2nd register number for
> > + vector pair, decimal 128-bit floating and IBM 128-bit binary floating
> > + values. */
> > if (!REG_P (x) || !VSX_REGNO_P (REGNO (x)))
> > - output_operand_lossage ("invalid %%x value");
> > + output_operand_lossage ("invalid %%%c value", (code == 'S' ? 'S' :
> > 'x'));
> > else
> > {
> > - int reg = REGNO (x);
> > + int reg = REGNO (x) + (code == 'S' ? 1 : 0);
> > int vsx_reg = (FP_REGNO_P (reg)
> > ? reg - 32
> > : reg - FIRST_ALTIVEC_REGNO + 32);
>
> The above looks good to me. However:
>
>
> > + : "=v" (*p)
> > + : "v" (*q), "v" (*r));
>
> These really should use "wa" rather than "v", since these are
> VSX instructions... or did you use those to ensure you got
> Altivec registers numbers assigned?
Yes in real code you would typically use "wa" instead of "v". I used them in
the test to ensure that I was getting a register to show the problem.
But I can imagine circumstances where you are doing extended asm with 2 or more
instructions, one that uses an instruction that uses the VSX encoding (where
you would use %S<n> and the other where you use the Altivec encoding where you
would use %L<n>, and you would use the "v" constraint.
> > +/* { dg-final { scan-assembler-times {\mxvadddp
> > (3[2-9]|[45][0-9]|6[0-3]),(3[2-9]|[45][0-9]|6[0-3]),(3[2-9]|[45][0-9]|6[0-3])\M}
> > 2 } } */
>
> ...and this is really ugly and hard to read/understand. Can't we use
> register variables to make it simpler? Something like the following
> which tests having both FPR and Altivec reg numbers assigned?
>
> ...
> void
> test (__vector_pair *ptr)
> {
> register __vector_pair p asm ("vs10");
> register __vector_pair q asm ("vs42");
> register __vector_pair r asm ("vs44");
> q = ptr[1];
> r = ptr[2];
> __asm__ ("xvadddp %x0,%x1,%x2\n\txvadddp %S0,%S1,%S2"
> : "=wa" (p)
> : "wa" (q), "wa" (r));
> ptr[2] = p;
> }
>
> /* { dg-final { scan-assembler-times {\mxvadddp 10,42,44\M} 1 } } */
> /* { dg-final { scan-assembler-times {\mxvadddp 11,43,45\M} 1 } } */
Yes that probably will work.
--
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: meiss...@linux.ibm.com
