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RE: Questions about match.pd


> > 2) Why doesn't the GIMPLE pass match on the GIMPLE code produced by
> the Fortran version?
> >    I have created an example where the GIMPLE trees of the two match
> exactly % some attributes
> >    on the expressions.
> 
> Fortran (and other frontends besides C-family) do not get their builtins from
> builtins.def but need to provide their own version.  See
> fortran/mathbuiltins.def.
> 

Ah! Thanks you! I had not realized this at all. It works perfectly in GIMPLE now.

> >
> > The rule seems to be matching early in the GIMPLE phase and not the
> generic, fair enough as long as it works.
> 
> Btw, why are you interested in GENERIC matching at all here?
> 

It was the road I ended up down when I was trying to debug the matches. I couldn't
Quite understand from the code why the GIMPLE one was rejecting the substitution but
The GENERIC one was simple enough to do. So I went with that.

>     {
>       tree fndecl = builtin_decl_implicit (as_builtin_fn (fn));
>       if (!fndecl)
>         return NULL_TREE;
>       return build_call_expr_loc_array (loc, fndecl, n, argarray);
> 
> but subject to the same implicit rule as GIMPLE (but handled more
> conservatively as I outlined above).

Ah, my confusion comes from not really knowing the difference between

builtin_decl_implicit (as_builtin_fn (fn));

and

internal_fn_p (fn)

well enough.
> 
> Yes, the FEs likely do not expect internal FNs around in the IL at random
> places.
> 
> So first of all I suggest to not try matching on GENERIC (or at least not spend
> too much energy in making it work there).
> 

Yes I'll drop the GENERIC one. I had thought I needed it for Fortran but that isn't the case.

Thanks for the help!

Regards,
Tamar

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