Re: [PATCH] VECT: Support CALL vectorization for COND_LEN_*

[Richard Biener <rguenther@suse.de>]

On Mon, 24 Jul 2023, juzhe.zhong@rivai.ai wrote:

> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
> 
> Hi, Richard and Richi.
> 
> This patch supports CALL vectorization by COND_LEN_*.
> 
> Consider this following case:
> void foo (float * __restrict a, float * __restrict b, int * __restrict cond, int n)
> {
>   for (int i = 0; i < n; i++)
>     if (cond[i])
>       a[i] = b[i] + a[i];
> }
> 
> 
> Output of RISC-V (32-bits) gcc (trunk) (Compiler #3)
> <source>:5:21: missed: couldn't vectorize loop
> <source>:5:21: missed: not vectorized: control flow in loop.
> 
> ARM SVE:
> 
> ...
> mask__27.10_51 = vect__4.9_49 != { 0, ... };
> ...
> vec_mask_and_55 = loop_mask_49 & mask__27.10_51;
> ...
> vect__9.17_62 = .COND_ADD (vec_mask_and_55, vect__6.13_56, vect__8.16_60, vect__6.13_56);
> 
> For RVV, we want IR as follows:
> 
> ...
> _68 = .SELECT_VL (ivtmp_66, POLY_INT_CST [4, 4]);
> ...
> mask__27.10_51 = vect__4.9_49 != { 0, ... };
> ...
> vect__9.17_60 = .COND_LEN_ADD (mask__27.10_51, vect__6.13_55, vect__8.16_59, vect__6.13_55, _68, 0);
> ...
> 
> Both len and mask of COND_LEN_ADD are real not dummy.
> 
> gcc/ChangeLog:
> 
>         * tree-if-conv.cc (ifcvt_can_predicate): Enable ifcvt for COND_LEN_*.
>         * tree-vect-stmts.cc (vectorizable_internal_function): Apply COND_LEN_*.
>         (vectorizable_call): Ditto.
> 
> ---
>  gcc/tree-if-conv.cc    |  7 +++-
>  gcc/tree-vect-stmts.cc | 84 +++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 83 insertions(+), 8 deletions(-)
> 
> diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
> index 799f071965e..2e17658b9ed 100644
> --- a/gcc/tree-if-conv.cc
> +++ b/gcc/tree-if-conv.cc
> @@ -1010,8 +1010,11 @@ ifcvt_can_predicate (gimple *stmt)
>    if (!types_compatible_p (lhs_type, rhs_type))
>      return false;
>    internal_fn cond_fn = get_conditional_internal_fn (code);
> -  return (cond_fn != IFN_LAST
> -	  && vectorized_internal_fn_supported_p (cond_fn, lhs_type));
> +  internal_fn cond_len_fn = get_conditional_len_internal_fn (code);
> +  return ((cond_fn != IFN_LAST
> +	   && vectorized_internal_fn_supported_p (cond_fn, lhs_type))
> +	  || (cond_len_fn != IFN_LAST
> +	      && vectorized_internal_fn_supported_p (cond_len_fn, lhs_type)));
>  }
>  
>  /* Return true when STMT is if-convertible.
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index ed28fbdced3..15401ddb682 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -1543,10 +1543,27 @@ vectorizable_internal_function (combined_fn cfn, tree fndecl,
>  				tree vectype_out, tree vectype_in)
>  {
>    internal_fn ifn;
> +  internal_fn len_ifn = IFN_LAST;
>    if (internal_fn_p (cfn))
> -    ifn = as_internal_fn (cfn);
> +    {
> +      ifn = as_internal_fn (cfn);
> +      tree_code code = conditional_internal_fn_code (ifn);
> +      len_ifn = get_conditional_len_internal_fn (code);
> +    }
>    else
>      ifn = associated_internal_fn (fndecl);

This function doesn't seem to care about conditional vectorization
support, so why are you changing it?

> +  if (len_ifn != IFN_LAST && direct_internal_fn_p (len_ifn))
> +    {
> +      const direct_internal_fn_info &info = direct_internal_fn (len_ifn);
> +      if (info.vectorizable)
> +	{
> +	  tree type0 = (info.type0 < 0 ? vectype_out : vectype_in);
> +	  tree type1 = (info.type1 < 0 ? vectype_out : vectype_in);
> +	  if (direct_internal_fn_supported_p (len_ifn, tree_pair (type0, type1),
> +					      OPTIMIZE_FOR_SPEED))
> +	    return len_ifn;
> +	}
> +    }
>    if (ifn != IFN_LAST && direct_internal_fn_p (ifn))
>      {
>        const direct_internal_fn_info &info = direct_internal_fn (ifn);
> @@ -3538,8 +3555,10 @@ vectorizable_call (vec_info *vinfo,
>    gcc_assert (ncopies >= 1);
>  
>    int reduc_idx = STMT_VINFO_REDUC_IDX (stmt_info);
> +  int len_index = internal_fn_len_index (ifn);

Note traditionally non-LEN fns would return -1 here, so ...

>    internal_fn cond_fn = get_conditional_internal_fn (ifn);
>    vec_loop_masks *masks = (loop_vinfo ? &LOOP_VINFO_MASKS (loop_vinfo) : NULL);
> +  vec_loop_lens *lens = (loop_vinfo ? &LOOP_VINFO_LENS (loop_vinfo) : NULL);
>    if (!vec_stmt) /* transformation not required.  */
>      {
>        if (slp_node)
> @@ -3585,8 +3604,12 @@ vectorizable_call (vec_info *vinfo,

instead there's code here that checks for the .COND_xxx case so you should
ament it for the len case as well?

>  	      tree scalar_mask = NULL_TREE;
>  	      if (mask_opno >= 0)
>  		scalar_mask = gimple_call_arg (stmt_info->stmt, mask_opno);
> -	      vect_record_loop_mask (loop_vinfo, masks, nvectors,
> -				     vectype_out, scalar_mask);
> +	      if (len_index >= 0)
> +		vect_record_loop_len (loop_vinfo, lens, nvectors, vectype_out,
> +				      1);
> +	      else
> +		vect_record_loop_mask (loop_vinfo, masks, nvectors, vectype_out,
> +				       scalar_mask);
>  	    }
>  	}
>        return true;
> @@ -3602,8 +3625,16 @@ vectorizable_call (vec_info *vinfo,
>    vec_dest = vect_create_destination_var (scalar_dest, vectype_out);
>  
>    bool masked_loop_p = loop_vinfo && LOOP_VINFO_FULLY_MASKED_P (loop_vinfo);
> +  bool len_loop_p = loop_vinfo && LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo);
>    unsigned int vect_nargs = nargs;
> -  if (masked_loop_p && reduc_idx >= 0)
> +  if (len_index)

what about reduc_indx?  Why check len_indes and not len_loop_p?

... checking len_index is going to be true for -1, you probably would
want len_index != -1 then?

> +    {
> +      /* COND_ADD --> COND_LEN_ADD with 2 more args (LEN + BIAS).
> +	 FIXME: We don't support FMAX --> COND_LEN_FMAX yet which
> +		needs 4 more args (MASK + ELSE + LEN + BIAS).  */
> +      vect_nargs += 2;
> +    }
> +  else if (masked_loop_p && reduc_idx >= 0)
>      {
>        ifn = cond_fn;
>        vect_nargs += 2;
> @@ -3670,7 +3701,29 @@ vectorizable_call (vec_info *vinfo,
>  		    }
>  		  else
>  		    {
> -		      if (mask_opno >= 0 && masked_loop_p)
> +		      if (len_index)

see above

> +			{
> +			  tree len, bias;
> +			  if (len_loop_p)
> +			    len
> +			      = vect_get_loop_len (loop_vinfo, gsi, lens,
> +						   ncopies, vectype_out, j, 1);
> +			  else
> +			    {
> +			      /* Dummy LEN.  */
> +			      tree iv_type
> +				= LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
> +			      len
> +				= build_int_cst (iv_type, TYPE_VECTOR_SUBPARTS (
> +							    vectype_out));
> +			    }
> +			  signed char biasval
> +			    = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
> +			  bias = build_int_cst (intQI_type_node, biasval);
> +			  vargs[varg++] = len;
> +			  vargs[varg++] = bias;
> +			}
> +		      else if (mask_opno >= 0 && masked_loop_p)
>  			{
>  			  unsigned int vec_num = vec_oprnds0.length ();
>  			  /* Always true for SLP.  */
> @@ -3718,7 +3771,26 @@ vectorizable_call (vec_info *vinfo,
>  	  if (masked_loop_p && reduc_idx >= 0)
>  	    vargs[varg++] = vargs[reduc_idx + 1];
>  
> -	  if (mask_opno >= 0 && masked_loop_p)
> +	  if (len_index)
> +	    {
> +	      tree len, bias;
> +	      if (len_loop_p)
> +		len = vect_get_loop_len (loop_vinfo, gsi, lens, ncopies,
> +					 vectype_out, j, 1);
> +	      else
> +		{
> +		  /* Dummy LEN.  */
> +		  tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
> +		  len = build_int_cst (iv_type,
> +				       TYPE_VECTOR_SUBPARTS (vectype_out));
> +		}
> +	      signed char biasval
> +		= LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
> +	      bias = build_int_cst (intQI_type_node, biasval);
> +	      vargs[varg++] = len;
> +	      vargs[varg++] = bias;


You are not actually using len_index to place the arguments.  See
how mask_opno is used.

You are producing patches too quickly, please double-check what you did
before posting for review.

Thanks,
Richard.

> +	    }
> +	  else if (mask_opno >= 0 && masked_loop_p)
>  	    {
>  	      tree mask = vect_get_loop_mask (loop_vinfo, gsi, masks, ncopies,
>  					      vectype_out, j);
>