Re: [ping][vect-patterns] Refactor widen_plus/widen_minus as internal_fns

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

Joel Hutton <Joel.Hutton@arm.com> writes:
>> > Patches attached. They already incorporated the .cc rename, now
>> > rebased to be after the change to tree.h
>>
>> @@ -1412,8 +1412,7 @@ vect_recog_widen_op_pattern (vec_info *vinfo,
>>                        2, oprnd, half_type, unprom, vectype);
>>
>>    tree var = vect_recog_temp_ssa_var (itype, NULL);
>> -  gimple *pattern_stmt = gimple_build_assign (var, wide_code,
>> -                                             oprnd[0], oprnd[1]);
>> +  gimple *pattern_stmt = gimple_build (var, wide_code, oprnd[0],
>> oprnd[1]);
>>
>>
>> you should be able to do without the new gimple_build overload
>> by using
>>
>>    gimple_seq stmts = NULL;
>>    gimple_build (&stmts, wide_code, itype, oprnd[0], oprnd[1]);
>>    gimple *pattern_stmt = gimple_seq_last_stmt (stmts);
>>
>> because 'gimple_build' is an existing API.
>
> Done.
>
> The gimple_build overload was at the request of Richard Sandiford, I assume removing it is ok with you Richard S?
> From Richard Sandiford:
>> For example, I think we should hide this inside a new:
>>
>>   gimple_build (var, wide_code, oprnd[0], oprnd[1]);
>>
>> that works directly on code_helper, similarly to the new code_helper
>> gimple_build interfaces.

I thought the potential problem with the above is that gimple_build
is a folding interface, so in principle it's allowed to return an
existing SSA_NAME set by an existing statement (or even a constant).
I think in this context we do need to force a new statement to be
created.

Of course, the hope is that there wouldn't still be such folding
opportunities at this stage, but I don't think it's guaranteed
(especially with options fuzzing).

Sind I was mentioned :-) ...

Could you run the patch through contrib/check_GNU_style.py?
There seem to be a few long lines.

> +  if (res_op.code.is_tree_code ())

Do you need this is_tree_code ()?  These comparisons…

> +  {
> +      widen_arith = (code == WIDEN_PLUS_EXPR
> +		     || code == WIDEN_MINUS_EXPR
> +		     || code == WIDEN_MULT_EXPR
> +		     || code == WIDEN_LSHIFT_EXPR);

…ought to be safe unconditionally.

> + }
> +  else
> +      widen_arith = false;
> +
> +  if (!widen_arith
> +      && !CONVERT_EXPR_CODE_P (code)
> +      && code != FIX_TRUNC_EXPR
> +      && code != FLOAT_EXPR)
> +    return false;
>  
>    /* Check types of lhs and rhs.  */
> -  scalar_dest = gimple_assign_lhs (stmt);
> +  scalar_dest = gimple_get_lhs (stmt);
>    lhs_type = TREE_TYPE (scalar_dest);
>    vectype_out = STMT_VINFO_VECTYPE (stmt_info);
>  
> @@ -4938,10 +4951,14 @@ vectorizable_conversion (vec_info *vinfo,
>  
>    if (op_type == binary_op)
>      {
> -      gcc_assert (code == WIDEN_MULT_EXPR || code == WIDEN_LSHIFT_EXPR
> -		  || code == WIDEN_PLUS_EXPR || code == WIDEN_MINUS_EXPR);
> +      gcc_assert (code == WIDEN_MULT_EXPR
> +		  || code == WIDEN_LSHIFT_EXPR
> +		  || code == WIDEN_PLUS_EXPR
> +		  || code == WIDEN_MINUS_EXPR);
>  
> -      op1 = gimple_assign_rhs2 (stmt);
> +
> +      op1 = is_gimple_assign (stmt) ? gimple_assign_rhs2 (stmt) :
> +				     gimple_call_arg (stmt, 0);
>        tree vectype1_in;
>        if (!vect_is_simple_use (vinfo, stmt_info, slp_node, 1,
>  			       &op1, &slp_op1, &dt[1], &vectype1_in))
> […]
> @@ -12181,7 +12235,6 @@ supportable_widening_operation (vec_info *vinfo,
>    return false;
>  }
>  
> -
>  /* Function supportable_narrowing_operation
>  
>     Check whether an operation represented by the code CODE is a

Seems like a spurious change.

> @@ -12205,7 +12258,7 @@ supportable_widening_operation (vec_info *vinfo,
>  bool
>  supportable_narrowing_operation (enum tree_code code,
>  				 tree vectype_out, tree vectype_in,
> -				 enum tree_code *code1, int *multi_step_cvt,
> +				 tree_code* _code1, int *multi_step_cvt,

The original formatting (space before the “*”) was correct.
Names beginning with _ are reserved, so I think we need a different
name here.  Also, the name in the comment should stay in sync with
the name in the code.

That said though, I'm not sure…

>                                   vec<tree> *interm_types)
>  {
>    machine_mode vec_mode;
> @@ -12217,8 +12270,8 @@ supportable_narrowing_operation (enum tree_code code,
>    tree intermediate_type, prev_type;
>    machine_mode intermediate_mode, prev_mode;
>    int i;
> -  unsigned HOST_WIDE_INT n_elts;
>    bool uns;
> +  tree_code * code1 = (tree_code*) _code1;

…the combination of these two changes makes sense on their own.

>  
>    *multi_step_cvt = 0;
>    switch (code)
> @@ -12227,9 +12280,8 @@ supportable_narrowing_operation (enum tree_code code,
>        c1 = VEC_PACK_TRUNC_EXPR;
>        if (VECTOR_BOOLEAN_TYPE_P (narrow_vectype)
>  	  && VECTOR_BOOLEAN_TYPE_P (vectype)
> -	  && SCALAR_INT_MODE_P (TYPE_MODE (vectype))
> -	  && TYPE_VECTOR_SUBPARTS (vectype).is_constant (&n_elts)
> -	  && n_elts < BITS_PER_UNIT)
> +	  && TYPE_MODE (narrow_vectype) == TYPE_MODE (vectype)
> +	  && SCALAR_INT_MODE_P (TYPE_MODE (vectype)))
>  	optab1 = vec_pack_sbool_trunc_optab;
>        else
>  	optab1 = optab_for_tree_code (c1, vectype, optab_default);
> @@ -12320,9 +12372,8 @@ supportable_narrowing_operation (enum tree_code code,
>  	  = lang_hooks.types.type_for_mode (intermediate_mode, uns);
>        if (VECTOR_BOOLEAN_TYPE_P (intermediate_type)
>  	  && VECTOR_BOOLEAN_TYPE_P (prev_type)
> -	  && SCALAR_INT_MODE_P (prev_mode)
> -	  && TYPE_VECTOR_SUBPARTS (intermediate_type).is_constant (&n_elts)
> -	  && n_elts < BITS_PER_UNIT)
> +	  && intermediate_mode == prev_mode
> +	  && SCALAR_INT_MODE_P (prev_mode))
>  	interm_optab = vec_pack_sbool_trunc_optab;
>        else
>  	interm_optab

This part looks like a behavioural change, so I think it should be part
of a separate patch.

> diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> index 642eb0aeb21264cd736a479b1ec25357abef29cd..50ff8eeac1e6b9859302bd784f10ee3d8ff4b4dc 100644
> --- a/gcc/tree-vectorizer.h
> +++ b/gcc/tree-vectorizer.h
> @@ -2120,13 +2120,12 @@ extern bool vect_is_simple_use (vec_info *, stmt_vec_info, slp_tree,
>  				enum vect_def_type *,
>  				tree *, stmt_vec_info * = NULL);
>  extern bool vect_maybe_update_slp_op_vectype (slp_tree, tree);
> -extern bool supportable_widening_operation (vec_info *,
> -					    enum tree_code, stmt_vec_info,
> -					    tree, tree, enum tree_code *,
> -					    enum tree_code *, int *,
> -					    vec<tree> *);
> +extern bool supportable_widening_operation (vec_info*, code_helper,
> +					    stmt_vec_info, tree, tree,
> +					    code_helper*, code_helper*,
> +					    int*, vec<tree> *);
>  extern bool supportable_narrowing_operation (enum tree_code, tree, tree,
> -					     enum tree_code *, int *,
> +					     tree_code *, int *,
>  					     vec<tree> *);
>  
>  extern unsigned record_stmt_cost (stmt_vector_for_cost *, int,
> diff --git a/gcc/tree.h b/gcc/tree.h
> index f84958933d51144bb6ce7cc41eca5f7f06814550..00b0e4d1c696633fe38baad5295b1f90398d53fc 100644
> --- a/gcc/tree.h
> +++ b/gcc/tree.h
> @@ -92,6 +92,10 @@ public:
>    bool is_fn_code () const { return rep < 0; }
>    bool is_internal_fn () const;
>    bool is_builtin_fn () const;
> +  enum tree_code safe_as_tree_code () const { return is_tree_code () ?
> +    (tree_code)* this : MAX_TREE_CODES; }
> +  combined_fn safe_as_fn_code () const { return is_fn_code () ? (combined_fn) *this
> +    : CFN_LAST;}

Since these don't fit on a line, the coding convention says that they
should be defined outside of the class.

Thanks,
Richard

>    int get_rep () const { return rep; }
>    bool operator== (const code_helper &other) { return rep == other.rep; }
>    bool operator!= (const code_helper &other) { return rep != other.rep; }