Vector shuffling

[Artem Shinkarov]

On Fri, Sep 2, 2011 at 4:41 PM, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Fri, 2 Sep 2011, Artem Shinkarov wrote:
>
>> +  /* Avoid C_MAYBE_CONST_EXPRs inside VEC_SHUFFLE_EXPR.  */
>> +  tmp = c_fully_fold (v0, false, &maybe_const);
>> +  v0 = save_expr (tmp);
>> +  wrap &= maybe_const;
>
> I suppose you need this save_expr because of the two-argument case, but
> shouldn't need it otherwise.
>
>> +  if (!two_arguments)
>> +    {
>> +      tmp = c_fully_fold (v1, false, &maybe_const);
>> +      v1 = save_expr (tmp);
>
> And you shouldn't need this save_expr at all.
>
>> +  tmp = c_fully_fold (mask, false, &maybe_const);
>> +  mask = save_expr (tmp);
>
> Or this one.

Joseph, I don't understand this comment. I have 2 or 3 arguments in
the VEC_SHUFFLE_EXPR and any of them can be C_MAYBE_CONST_EXPR, so I
need to wrap mask (the last argument) to avoid the following failure:

#define vector(elcount, type)  \
 __attribute__((vector_size((elcount)*sizeof(type)))) type

extern int p, q, v, r;
int main ()
{
  vector (4, int) i0 = {argc, 1,2,3};
  vector (4, int) i1 = {argc, 1, argc, 3};
  vector (4, int) imask = {0,3,2,1};
  vector (4, int) extmask = {p,q,r,v};
  i2 = __builtin_shuffle (i0, (p,q)? imask:extmask);
  return 0;
}

and the same failure would happen if __builtin_shuffle expression will
be in the following form:
i2 = __builtin_shuffle (i0, (p,q)? imask:extmask, i2);

All the rest -- agreed, and is fixed already.


Thanks,
Artem.

>> +/* Helper function to read arguments of builtins which are interfaces
>> +   for the middle-end nodes like COMPLEX_EXPR, VEC_SHUFLE_EXPR and
>
> Spelling of SHUFFLE.
>
>> +   others. The name of the builtin is passed using BNAME parameter.
>
> Two spaces after ".".
>
>> +   Function returns true if there were no errors while parsing and
>> +   stores the arguments in EXPR_LIST*/
>
> ".  " at end of comment.
>
>> +static bool
>> +c_parser_get_builtin_args (c_parser *  parser, const char *  bname,
>> +                        VEC(tree,gc) **  expr_list)
>
> No spaces after "*".
>
>> +  if (c_parser_next_token_is_not (parser, CPP_OPEN_PAREN))
>> +    {
>> +      error_at (loc, "cannot take address of %<%s%>", bname);
>
> %qs is a simpler form of %<%s%>.
>
>> @@ -6461,6 +6500,35 @@ c_parser_postfix_expression (c_parser *p
>
> Should also convert __builtin_choose_expr and __builtin_complex to use the
> new helper.
>
>> +         if (! c_parser_get_builtin_args (parser,
>
> No space after "!".
>
>> +           {
>> +             error_at (loc, "%<__builtin_shuffle%> wrong number of arguments");
>
> "wrong number of arguments to %<__builtin_shuffle%>".
>
> --
> Joseph S. Myers
> joseph@codesourcery.com
>