Re: [PATCH V3] SCCVN: Add LEN_MASK_STORE and fix LEN_STORE

[Richard Biener <rguenther@suse.de>]

On Mon, 26 Jun 2023, juzhe.zhong@rivai.ai wrote:

> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
> 
> Hi, Richi. It seems that we use nunits which is len + bias to iterate then we can
> simplify the codes.
> 
> Also, I fixed behavior of len_store,
> 
> Before this patch:
>    (len - bias) * BITS_PER_UNIT
> After this patch:
>    (len + bias) * BITS_PER_UNIT
>    
> gcc/ChangeLog:
> 
>         * tree-ssa-sccvn.cc (vn_reference_lookup_3): Add LEN_MASK_STORE and fix LEN_STORE.
> 
> ---
>  gcc/tree-ssa-sccvn.cc | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
> index 11061a374a2..d66e75460ed 100644
> --- a/gcc/tree-ssa-sccvn.cc
> +++ b/gcc/tree-ssa-sccvn.cc
> @@ -3304,6 +3304,16 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
>  	  if (!tree_fits_uhwi_p (len) || !tree_fits_shwi_p (bias))
>  	    return (void *)-1;
>  	  break;
> +	case IFN_LEN_MASK_STORE:
> +	  len = gimple_call_arg (call, 2);
> +	  bias = gimple_call_arg (call, 5);
> +	  if (!tree_fits_uhwi_p (len) || !tree_fits_shwi_p (bias))
> +	    return (void *)-1;
> +	  mask = gimple_call_arg (call, internal_fn_mask_index (fn));
> +	  mask = vn_valueize (mask);
> +	  if (TREE_CODE (mask) != VECTOR_CST)
> +	    return (void *)-1;
> +	  break;
>  	default:
>  	  return (void *)-1;
>  	}
> @@ -3344,6 +3354,16 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
>  	      tree vectype = TREE_TYPE (def_rhs);
>  	      unsigned HOST_WIDE_INT elsz
>  		= tree_to_uhwi (TYPE_SIZE (TREE_TYPE (vectype)));
> +	      poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (vectype);
> +	      if (len)
> +		{
> +		  /* Since the following while condition known_lt
> +		     (mask_idx, nunits) will exit the while loop
> +		     when mask_idx > nunits.coeffs[0], we pick the
> +		     MIN (nunits.coeffs[0], len + bias).  */
> +		  nunits = MIN (nunits.coeffs[0],
> +				tree_to_uhwi (len) + tree_to_shwi (bias));

I think you can use ordered_min here?  Alternatively doing ...

> +		}
>  	      if (mask)
>  		{
>  		  HOST_WIDE_INT start = 0, length = 0;
> @@ -3373,7 +3393,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
>  			length += elsz;
>  		      mask_idx++;
>  		    }
> -		  while (known_lt (mask_idx, TYPE_VECTOR_SUBPARTS (vectype)));
> +		  while (known_lt (mask_idx, nunits));

&& mask_id < len

would be possible.

Richard?

Thanks,
Richard.