Re: [2/2] PR96463 -- changes to type checking vec_perm_expr in middle end

[Richard Biener <rguenther@suse.de>]

On Fri, 17 Dec 2021, Richard Sandiford wrote:

> Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> writes:
> > Hi,
> > The attached patch rearranges order of type-check for vec_perm_expr
> > and relaxes type checking for
> > lhs = vec_perm_expr<rhs1, rhs2, mask>
> >
> > when:
> > rhs1 == rhs2,
> > lhs is variable length vector,
> > rhs1 is fixed length vector,
> > TREE_TYPE (lhs) == TREE_TYPE (rhs1)
> >
> > I am not sure tho if this check is correct ? My intent was to capture
> > case when vec_perm_expr is used to "extend" fixed length vector to
> > it's VLA equivalent.
> 
> VLAness isn't really the issue.  We want the same thing to work for
> -msve-vector-bits=256, -msve-vector-bits=512, etc., even though the
> vectors are fixed-length in that case.
> 
> The principle is that for:
> 
>   A = VEC_PERM_EXPR <B, C, D>;
> 
> the requirements are:
> 
> - A, B, C and D must be vectors
> - A, B and C must have the same element type
> - D must have an integer element type
> - A and D must have the same number of elements (NA)
> - B and C must have the same number of elements (NB)
> 
> The semantics are that we create a joined vector BC (all elements of B
> followed by all element of C) and that:
> 
>   A[i] = BC[D[i] % (NB+NB)]
> 
> for 0 ≤ i < NA.
> 
> This operation makes sense even if NA != NB.

But note that we don't currently expect NA != NB and the optab just
has a single mode.

I'd rather go with the simpler patch I posted as reply to the earlier
mail rather such large refactoring at this point.

Richard.

> Thanks,
> Richard
> 
> >
> > Thanks,
> > Prathamesh
> >
> > diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
> > index 672e384ef09..9f91878c468 100644
> > --- a/gcc/tree-cfg.c
> > +++ b/gcc/tree-cfg.c
> > @@ -4325,10 +4325,11 @@ verify_gimple_assign_ternary (gassign *stmt)
> >        break;
> >  
> >      case VEC_PERM_EXPR:
> > -      if (!useless_type_conversion_p (lhs_type, rhs1_type)
> > -	  || !useless_type_conversion_p (lhs_type, rhs2_type))
> > +      if (TREE_CODE (rhs1_type) != VECTOR_TYPE
> > +	  || TREE_CODE (rhs2_type) != VECTOR_TYPE
> > +	  || TREE_CODE (rhs3_type) != VECTOR_TYPE)
> >  	{
> > -	  error ("type mismatch in %qs", code_name);
> > +	  error ("vector types expected in %qs", code_name);
> >  	  debug_generic_expr (lhs_type);
> >  	  debug_generic_expr (rhs1_type);
> >  	  debug_generic_expr (rhs2_type);
> > @@ -4336,11 +4337,14 @@ verify_gimple_assign_ternary (gassign *stmt)
> >  	  return true;
> >  	}
> >  
> > -      if (TREE_CODE (rhs1_type) != VECTOR_TYPE
> > -	  || TREE_CODE (rhs2_type) != VECTOR_TYPE
> > -	  || TREE_CODE (rhs3_type) != VECTOR_TYPE)
> > +      if (TREE_CODE (TREE_TYPE (rhs3_type)) != INTEGER_TYPE
> > +	  || (TREE_CODE (rhs3) != VECTOR_CST
> > +	      && (GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE
> > +				    (TREE_TYPE (rhs3_type)))
> > +		  != GET_MODE_BITSIZE (SCALAR_TYPE_MODE
> > +				       (TREE_TYPE (rhs1_type))))))
> >  	{
> > -	  error ("vector types expected in %qs", code_name);
> > +	  error ("invalid mask type in %qs", code_name);
> >  	  debug_generic_expr (lhs_type);
> >  	  debug_generic_expr (rhs1_type);
> >  	  debug_generic_expr (rhs2_type);
> > @@ -4348,15 +4352,18 @@ verify_gimple_assign_ternary (gassign *stmt)
> >  	  return true;
> >  	}
> >  
> > -      if (maybe_ne (TYPE_VECTOR_SUBPARTS (rhs1_type),
> > -		    TYPE_VECTOR_SUBPARTS (rhs2_type))
> > -	  || maybe_ne (TYPE_VECTOR_SUBPARTS (rhs2_type),
> > -		       TYPE_VECTOR_SUBPARTS (rhs3_type))
> > -	  || maybe_ne (TYPE_VECTOR_SUBPARTS (rhs3_type),
> > -		       TYPE_VECTOR_SUBPARTS (lhs_type)))
> > +      /* Accept lhs = vec_perm_expr<v, v, mask> if lhs is vector length agnostic,
> > +	 and has same element type as v.  */
> > +      if (!TYPE_VECTOR_SUBPARTS (lhs_type).is_constant ()
> > +	  && operand_equal_p (rhs1, rhs2, 0)
> > +	  && TYPE_VECTOR_SUBPARTS (rhs1_type).is_constant ()
> > +	  && TREE_TYPE (lhs_type) == TREE_TYPE (rhs1_type)) 
> > +	return false;
> > +
> > +      if (!useless_type_conversion_p (lhs_type, rhs1_type)
> > +	  || !useless_type_conversion_p (lhs_type, rhs2_type))
> >  	{
> > -	  error ("vectors with different element number found in %qs",
> > -		 code_name);
> > +	  error ("type mismatch in %qs", code_name);
> >  	  debug_generic_expr (lhs_type);
> >  	  debug_generic_expr (rhs1_type);
> >  	  debug_generic_expr (rhs2_type);
> > @@ -4364,21 +4371,21 @@ verify_gimple_assign_ternary (gassign *stmt)
> >  	  return true;
> >  	}
> >  
> > -      if (TREE_CODE (TREE_TYPE (rhs3_type)) != INTEGER_TYPE
> > -	  || (TREE_CODE (rhs3) != VECTOR_CST
> > -	      && (GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE
> > -				    (TREE_TYPE (rhs3_type)))
> > -		  != GET_MODE_BITSIZE (SCALAR_TYPE_MODE
> > -				       (TREE_TYPE (rhs1_type))))))
> > +      if (maybe_ne (TYPE_VECTOR_SUBPARTS (rhs1_type),
> > +		    TYPE_VECTOR_SUBPARTS (rhs2_type))
> > +	  || maybe_ne (TYPE_VECTOR_SUBPARTS (rhs2_type),
> > +		       TYPE_VECTOR_SUBPARTS (rhs3_type))
> > +	  || maybe_ne (TYPE_VECTOR_SUBPARTS (rhs3_type),
> > +		       TYPE_VECTOR_SUBPARTS (lhs_type)))
> >  	{
> > -	  error ("invalid mask type in %qs", code_name);
> > +	  error ("vectors with different element number found in %qs",
> > +		 code_name);
> >  	  debug_generic_expr (lhs_type);
> >  	  debug_generic_expr (rhs1_type);
> >  	  debug_generic_expr (rhs2_type);
> >  	  debug_generic_expr (rhs3_type);
> >  	  return true;
> >  	}
> > -
> >        return false;
> >  
> >      case SAD_EXPR:
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)