Re: [PATCH 2/4 GCC11] Add target hook stride_dform_valid_p

[Richard Sandiford <richard dot sandiford at arm dot com>]

"Kewen.Lin" <linkw@linux.ibm.com> writes:
> gcc/ChangeLog
>
> 2020-01-16  Kewen Lin  <linkw@gcc.gnu.org>
>
> 	* config/rs6000/rs6000.c (TARGET_STRIDE_DFORM_VALID_P): New macro.
> 	(rs6000_stride_dform_valid_p): New function.
> 	* doc/tm.texi: Regenerate.
> 	* doc/tm.texi.in (TARGET_STRIDE_DFORM_VALID_P): New hook.
> 	* target.def (stride_dform_valid_p): New hook.

It looks like we should able to derive this information from the normal
legitimate_address_p hook.

Also, "D-form" vs. "X-form" is AFAIK a PowerPC-specific classification.
It would be good to use a more generic term in target-independent code.

Thanks,
Richard



>
>  gcc/config/rs6000/rs6000.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  gcc/doc/tm.texi            |  8 ++++++++
>  gcc/doc/tm.texi.in         |  2 ++
>  gcc/target.def             | 13 ++++++++++++-
>  4 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 0dabaa6..1e41fcf 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -1657,6 +1657,9 @@ static const struct attribute_spec rs6000_attribute_table[] =
>  #undef TARGET_PREDICT_DOLOOP_P
>  #define TARGET_PREDICT_DOLOOP_P rs6000_predict_doloop_p
>  
> +#undef TARGET_STRIDE_DFORM_VALID_P
> +#define TARGET_STRIDE_DFORM_VALID_P rs6000_stride_dform_valid_p
> +
>  #undef TARGET_HAVE_COUNT_REG_DECR_P
>  #define TARGET_HAVE_COUNT_REG_DECR_P true
>  
> @@ -26272,6 +26275,43 @@ rs6000_predict_doloop_p (struct loop *loop)
>    return true;
>  }
>  
> +/* Return true if the memory access with mode MODE, signedness SIGNED_P and
> +   store STORE_P with offset from 0 to (NUNROLL-1) * STRIDE are valid with
> +   D-form instructions.  */
> +
> +static bool
> +rs6000_stride_dform_valid_p (machine_mode mode, signed HOST_WIDE_INT stride,
> +			  bool signed_p, bool store_p, unsigned nunroll)
> +{
> +  static const HOST_WIDE_INT max_bound = 0x7fff;
> +  static const HOST_WIDE_INT min_bound = -0x8000;
> +
> +  if (!IN_RANGE ((nunroll - 1) * stride, min_bound, max_bound))
> +    return false;
> +
> +  /* Check DQ-form for vector mode or float128 mode.  */
> +  if (VECTOR_MODE_P (mode) || FLOAT128_VECTOR_P (mode))
> +    {
> +      if (mode_supports_dq_form (mode) && !(stride & 0xF))
> +	return true;
> +      else
> +	return false;
> +    }
> +
> +  /* Simply consider non VSX instructions.  */
> +  if (mode == QImode || mode == HImode || mode == SFmode || mode == DFmode)
> +    return true;
> +
> +  /* lwz/stw is D-form, but lwa is DS-form.  */
> +  if (mode == SImode && (!signed_p || store_p || !(stride & 0x03)))
> +    return true;
> +
> +  if (mode == DImode && !(stride & 0x03))
> +    return true;
> +
> +  return false;
> +}
> +
>  struct gcc_target targetm = TARGET_INITIALIZER;
>  
>  #include "gt-rs6000.h"
> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> index 86ad278..0b8bc7c 100644
> --- a/gcc/doc/tm.texi
> +++ b/gcc/doc/tm.texi
> @@ -11669,6 +11669,14 @@ function version at run-time for a given set of function versions.
>  body must be generated.
>  @end deftypefn
>  
> +@deftypefn {Target Hook} bool TARGET_STRIDE_DFORM_VALID_P (machine_mode @var{mode}, signed HOST_WIDE_INT @var{stride}, bool @var{signed_p}, bool @var{store_p}, unsigned @var{nunroll})
> +For a given memory access, check whether it is valid to put 0, @var{stride}
> +, 2 * @var{stride}, ... , (@var{nunroll} - 1) to the instruction D-form
> +displacement, with mode @var{mode}, signedness @var{signed_p} and store
> +@var{store_p}.  Return true if valid.
> +The default version of this hook returns false.
> +@end deftypefn
> +
>  @deftypefn {Target Hook} bool TARGET_PREDICT_DOLOOP_P (class loop *@var{loop})
>  Return true if we can predict it is possible to use a low-overhead loop
>  for a particular loop.  The parameter @var{loop} is a pointer to the loop.
> diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> index fd9769e..e90d020 100644
> --- a/gcc/doc/tm.texi.in
> +++ b/gcc/doc/tm.texi.in
> @@ -7953,6 +7953,8 @@ to by @var{ce_info}.
>  
>  @hook TARGET_GENERATE_VERSION_DISPATCHER_BODY
>  
> +@hook TARGET_STRIDE_DFORM_VALID_P
> +
>  @hook TARGET_PREDICT_DOLOOP_P
>  
>  @hook TARGET_HAVE_COUNT_REG_DECR_P
> diff --git a/gcc/target.def b/gcc/target.def
> index f61c831..ee19a8d 100644
> --- a/gcc/target.def
> +++ b/gcc/target.def
> @@ -4300,7 +4300,18 @@ DEFHOOK
>   emits a @code{speculation_barrier} instruction if that is defined.",
>  rtx, (machine_mode mode, rtx result, rtx val, rtx failval),
>   default_speculation_safe_value)
> - 
> +
> +DEFHOOK
> +(stride_dform_valid_p,
> + "For a given memory access, check whether it is valid to put 0, @var{stride}\n\
> +, 2 * @var{stride}, ... , (@var{nunroll} - 1) to the instruction D-form\n\
> +displacement, with mode @var{mode}, signedness @var{signed_p} and store\n\
> +@var{store_p}.  Return true if valid.\n\
> +The default version of this hook returns false.",
> + bool, (machine_mode mode, signed HOST_WIDE_INT stride, bool signed_p,
> + bool store_p, unsigned nunroll),
> + NULL)
> +
>  DEFHOOK
>  (predict_doloop_p,
>   "Return true if we can predict it is possible to use a low-overhead loop\n\