Re: [PATCH], Add PowerPC ISA 3.0 vector extract support

[Segher Boessenkool <segher at kernel dot crashing dot org>]

On Wed, Jun 29, 2016 at 03:33:24PM -0400, Michael Meissner wrote:
> Is it ok to install in the trunk?

See comments below.  Okay with that taken care of.

> Ideally, I would like to also install it on the GCC 6.2 branch.  Note, it
> depends on the June 15th changes to allow DImode into Altivec registers, and
> the fix for PR 71677 that was submitted on June 27th being installed before
> these patches can be applied.

Is the DImode thing not on trunk yet?

> Assuming the above patches are supplied can I back port it to the GCC 6.2 after
> a burn-in period?

Yes, thanks.


> +;; Mode attribute to give the instruction for vector extract.  %3 contains the
> +;; adjusted element count.
> +(define_mode_attr VSX_EXTRACT_INSN [(V16QI "vextractub %0,%1,%3")
> +				    (V8HI  "vextractuh %0,%1,%3")
> +				    (V4SI  "xxextractuw %x0,%x1,%3")])

Could you use %2 instead, please?  Much less surprising.  And please inline
it in the one place it is used.

> +(define_insn  "vsx_extract_<mode>_di"
> +  [(set (match_operand:DI 0 "gpc_reg_operand" "=<VSX_EX>")
> +	(zero_extend:DI
> +	 (vec_select:<VS_scalar>
> +	  (match_operand:VSX_EXTRACT_I 1 "gpc_reg_operand" "<VSX_EX>")
> +	  (parallel [(match_operand:QI 2 "<VSX_EXTRACT_PREDICATE>" "n")]))))]
> +  "VECTOR_MEM_VSX_P (<MODE>mode) && TARGET_VEXTRACTUB"
> +{
> +  int element = INTVAL (operands[2]);
> +  int unit_size = GET_MODE_UNIT_SIZE (<MODE>mode);
> +  int offset = ((VECTOR_ELT_ORDER_BIG)
> +		? unit_size * element
> +		: unit_size * (GET_MODE_NUNITS (<MODE>mode) - 1 - element));
> +
> +  operands[3] = GEN_INT (offset);
> +  return "<VSX_EXTRACT_INSN>";
> +}

So that would be

  operands[2] = GEN_INT (offset);
  if (unit_size == 4)
    return "xxextractuw %x0,%x1,%2";
  else
    return "vextractu<wd> %0,%1,%2";

or such.


Segher