Re: [PATCH] tree-vect-generic: Fix up ICE with SSA_NAME_OCCURS_IN_ABNORMAL_PHI [PR109392]

[Richard Biener <rguenther@suse.de>]

On Tue, 11 Apr 2023, Jakub Jelinek wrote:

> On Wed, Apr 05, 2023 at 02:11:08PM +0200, Richard Biener wrote:
> > Ok, but maybe there?s a gimple_build overload that meanwhile implements
> > the desired semantics?  It would probably need to specify the valueization
> > hook to follow SSA edges beyond the sequence we?re currently building.
> 
> Jeff has apparently committed the patch in the meantime.
> For gimple_build, did you mean to use it just for this fallback case,
> or instead of the initial resimplification as well?

I was originally thinking of the initial resimplification.

But yes, using gimple_build would have simplified it to

  if (!res)
    res = gimple_build (&stmts, BIT_FIELD_REF, type, t, bitsize, bitpos);

With the gsi overloads the whole function should now be able to
be turned into

return gimple_build (gsi, true, GSI_SAME_STMT, UNKNOWN_LOCATION,
                     BIT_FIELD_REF, type, t, bitsize, bitpos);

I think.  Note that's not 100% equivalent to what we do now, so it's
probably better to defer to stage1.  What it doesn't do is

  /* We're using the resimplify API and maybe_push_res_to_seq to
     simplify the BIT_FIELD_REF but restrict the simplification to 
     a single stmt while at the same time following SSA edges for
     simplification with already emitted CTORs.  */

which is achieved by passing NULL as the gimple_seq * argument to
.resimplify.  The above replacement would instead do what a later
forwprop pass would do when folding.  ISTR I wanted to do minimal
changes when rewriting this.

Richard.

> > > 2023-04-05  Jakub Jelinek  <jakub@redhat.com>
> > > 
> > >    PR tree-optimization/109392
> > >    * tree-vect-generic.cc (tree_vec_extract): If maybe_push_res_to_seq
> > >    fails, build BIT_FIELD_REF insn without trying to simplify it.
> > > 
> > >    * gcc.dg/pr109392.c: New test.
> > > 
> > > --- gcc/tree-vect-generic.cc.jj    2023-03-23 10:02:18.997935620 +0100
> > > +++ gcc/tree-vect-generic.cc    2023-04-04 14:28:32.977729134 +0200
> > > @@ -174,7 +174,16 @@ tree_vec_extract (gimple_stmt_iterator *
> > >   opr.resimplify (NULL, follow_all_ssa_edges);
> > >   gimple_seq stmts = NULL;
> > >   tree res = maybe_push_res_to_seq (&opr, &stmts);
> > > -  gcc_assert (res);
> > > +  if (!res)
> > > +    {
> > > +      /* This can happen if SSA_NAME_OCCURS_IN_ABNORMAL_PHI are
> > > +     used.  Build BIT_FIELD_REF manually otherwise.  */
> > > +      t = build3 (BIT_FIELD_REF, type, t, bitsize, bitpos);
> > > +      res = make_ssa_name (type);
> > > +      gimple *g = gimple_build_assign (res, t);
> > > +      gsi_insert_before (gsi, g, GSI_SAME_STMT);
> > > +      return res;
> > > +    }
> > >   gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> > >   return res;
> > > }
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
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