Re: [PATCH v2 06/11] aarch64: Fix up aarch64_print_operand xzr/wzr case

[Richard Sandiford <richard.sandiford@arm.com>]

Alex Coplan <alex.coplan@arm.com> writes:
> Hi,
>
> This is a v2 of:
>
> https://gcc.gnu.org/pipermail/gcc-patches/2023-November/637612.html
>
> v1 was approved as-is, but this version pulls out the test into a helper
> function which is used by later patches in the series.
>
> Bootstrapped/regtested as a series on aarch64-linux-gnu, OK for trunk?
>
> Thanks,
> Alex
>
> -- >8 --
>
> This adjusts aarch64_print_operand to recognize zero rtxes in modes other than
> VOIDmode.  This allows us to use xzr/wzr for zero vectors, for example.
>
> We extract the test into a helper function, aarch64_const_zero_rtx_p, since this
> predicate is needed by later patches.
>
> gcc/ChangeLog:
>
> 	* config/aarch64/aarch64-protos.h (aarch64_const_zero_rtx_p): New.
> 	* config/aarch64/aarch64.cc (aarch64_const_zero_rtx_p): New.
> 	Use it ...
> 	(aarch64_print_operand): ... here.  Recognize CONST0_RTXes in
> 	modes other than VOIDmode.
>
> diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
> index d2718cc87b3..27fc6ccf098 100644
> --- a/gcc/config/aarch64/aarch64-protos.h
> +++ b/gcc/config/aarch64/aarch64-protos.h
> @@ -773,6 +773,7 @@ bool aarch64_expand_cpymem (rtx *);
>  bool aarch64_expand_setmem (rtx *);
>  bool aarch64_float_const_zero_rtx_p (rtx);
>  bool aarch64_float_const_rtx_p (rtx);
> +bool aarch64_const_zero_rtx_p (rtx);
>  bool aarch64_function_arg_regno_p (unsigned);
>  bool aarch64_fusion_enabled_p (enum aarch64_fusion_pairs);
>  bool aarch64_gen_cpymemqi (rtx *);
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index fca64daf2a0..a35c6bbe335 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -9095,6 +9095,15 @@ aarch64_float_const_zero_rtx_p (rtx x)
>    return real_equal (CONST_DOUBLE_REAL_VALUE (x), &dconst0);
>  }
>  
> +/* Return true if X is any kind of constant zero rtx.  */
> +
> +bool
> +aarch64_const_zero_rtx_p (rtx x)
> +{
> +  return x == CONST0_RTX (GET_MODE (x))
> +    || (CONST_DOUBLE_P (x) && aarch64_float_const_zero_rtx_p (x));
> +}
> +

Think this is easier to read if formatted as:

  return (x == CONST0_RTX (GET_MODE (x))
	  || (CONST_DOUBLE_P (x) && aarch64_float_const_zero_rtx_p (x)));

OK with that change (or as-is if you prefer).  Thanks for splitting
the function out.

Richard

>  /* Return TRUE if rtx X is immediate constant that fits in a single
>     MOVI immediate operation.  */
>  bool
> @@ -9977,8 +9986,7 @@ aarch64_print_operand (FILE *f, rtx x, int code)
>  
>      case 'w':
>      case 'x':
> -      if (x == const0_rtx
> -	  || (CONST_DOUBLE_P (x) && aarch64_float_const_zero_rtx_p (x)))
> +      if (aarch64_const_zero_rtx_p (x))
>  	{
>  	  asm_fprintf (f, "%czr", code);
>  	  break;