> -----Original Message-----
> From: Richard Biener <[email protected]>
> Sent: 27 October 2025 09:06
> To: Andrew Pinski <[email protected]>
> Cc: Tamar Christina <[email protected]>; [email protected];
> nd <[email protected]>
> Subject: Re: [PATCH]middle-end: Don't ICE during gimple_build of an
> incomplete PHI node
>
> On Sun, 26 Oct 2025, Andrew Pinski wrote:
>
> > On Sat, Oct 25, 2025 at 2:54 AM Tamar Christina
> <[email protected]> wrote:
> > >
> > > The new building APIs e.g. gimple_build APIs at the moment ICE if you try
> to
> > > build a PHI node without all the arguments set yet. However this workflow
> is
> > > quite common, especially in the vectorizer.
> > >
> > > This change allows this case by just not folding the PHI is any argument
> > > is
> > > missing as we don't know the value, we also don't know if it's
> > > nonnegative.
> > >
> > > Bootstrapped Regtested on aarch64-none-linux-gnu,
> > > arm-none-linux-gnueabihf, x86_64-pc-linux-gnu
> > > -m32, -m64 and no issues
> > >
> > > Ok for master?
> >
> > I ran into the same issue before and Richi rejected a similar patch; I
> > was also checking if the ssa name was in the free list.
> >
> > See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120280#c10 and
> afterwards .
> >
> > That is the match.pd patterns are broken for not passing down the
> > valueizer and checking the results there. I have not looked into
> > cleaning up the mess either :(.
>
> Heh, so I did forget this older advice but in the end I have to agree
> with myself. The PR hints at a solution with the #define - I'll note
> that tree_single_nonnegative_warnv_p already has a partial workaround
> for some issues with checking name_registered_for_update_p.
>
Ironically you were the one that suggested this fix to me :)
> Partially invalid IL _is_ a problem for SSA walking things, I wonder to
> what extent we can avoid this here though - short of putting temporary
> PHI args in there, but those would need to be reliably 'VARYING' in
> all senses which is difficult - putting in error_mark_node might
> do the trick?
>
I could, but it seems odd to have to iterate over every PHI node twice.
I'll just do that then, it's just so ugly though :(
Thanks,
Tamar.
> Richard.
>
> > Thanks,
> > Andrew
> >
> > >
> > > Thanks,
> > > Tamar
> > >
> > > gcc/ChangeLog:
> > >
> > > * gimple-fold.cc (gimple_phi_nonnegative_warnv_p): If the
> > > arguments
> > > aren't defined, then return false.
> > >
> > > ---
> > > diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
> > > index
> edcc04adc08cf15cff36d436caa31c0cfbff8f9a..bed760b9c0d538e2f874f5a1
> 263a0d2db5486a86 100644
> > > --- a/gcc/gimple-fold.cc
> > > +++ b/gcc/gimple-fold.cc
> > > @@ -11386,7 +11386,9 @@ gimple_phi_nonnegative_warnv_p (gimple
> *stmt, bool *strict_overflow_p,
> > > for (unsigned i = 0; i < gimple_phi_num_args (stmt); ++i)
> > > {
> > > tree arg = gimple_phi_arg_def (stmt, i);
> > > - if (!tree_single_nonnegative_warnv_p (arg, strict_overflow_p,
> > > depth +
> 1))
> > > + if (!arg
> > > + || !tree_single_nonnegative_warnv_p (arg, strict_overflow_p,
> > > + depth + 1))
> > > return false;
> > > }
> > > return true;
> > >
> > >
> > > --
> >
>
> --
> Richard Biener <[email protected]>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG
> Nuernberg)
