On Tue, Dec 03, 2024 at 01:28:28PM +0100, Richard Biener wrote:
> On Mon, Dec 2, 2024 at 1:55 AM Lewis Hyatt <lhy...@gmail.com> wrote:
> >
> > This patch is my new way to handle what was previously done in v2 patch
> > 04/14, discussed at:
> > https://gcc.gnu.org/pipermail/gcc-patches/2024-November/669527.html
> >
> > The only places I have found running into trouble with reallocated PHI nodes
> > (at least, the only places revealed by changing the size of location_t) are
> > those which remember a gphi object before a call to loop_version() and then
> > try to use it after. I fixed three affected call sites in this new patch.
>
> I guess it might be nice to avoid PHI node re-allocation by loop_version(),
> I remember fixing up other CFG manipulations to avoid the need for
> intermittent more PHI arguments. Anway, the patch is OK besides one
> minor adjustment, see below ...
>
Thanks again for looking at all the patches. Comment below...
...
> > diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> > index 54b29540eb5..4f3abb94e6a 100644
> > --- a/gcc/tree-vect-loop-manip.cc
> > +++ b/gcc/tree-vect-loop-manip.cc
> > @@ -4190,6 +4190,14 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
> > prob * prob2, (prob * prob2).invert (),
> > prob * prob2, (prob * prob2).invert (),
> > true);
> > +
> > + /* If the PHI nodes in the loop header were reallocated, we need to
> > fix up
> > + our internally stashed copies of those. */
> > + if (loop_to_version == loop)
> > + for (auto gsi = gsi_start_phis (loop->header);
> > + !gsi_end_p (gsi); gsi_next (&gsi))
> > + loop_vinfo->resync_stmt_addr (gsi.phi ());
>
> Instead of a new resync_stmt_addr method can you simply do
>
> if (stmt_vec_info s = loop_vinfo->lookup_stmt (gsi.phi ())
> STMT_VINFO_STMT (s) = gsi.phi ();
>
> please?
>
> OK with that change.
>
> Thanks,
> Richard.
The reason I added the new function is that lookup_stmt() does:
if (res && res->stmt == stmt)
return res;
so it returns NULL if the stored stmt does not match the one that was looked
up. I could add a "bool relaxed = false" argument to lookup_stmt() instead,
or could add an alternate function lookup_stmt_relaxed() if you prefer? I
guess the second option would be pretty similar to what I did with
resync_stmt_addr(), just it would not actually make the change within the
function itself.
>
> > +
> > /* We will later insert second conditional so overall outcome of
> > both is prob * prob2. */
> > edge true_e, false_e;
> > diff --git a/gcc/tree-vectorizer.cc b/gcc/tree-vectorizer.cc
> > index 9a068a40864..c8bb0fe14fc 100644
> > --- a/gcc/tree-vectorizer.cc
> > +++ b/gcc/tree-vectorizer.cc
> > @@ -541,6 +541,26 @@ vec_info::add_pattern_stmt (gimple *stmt,
> > stmt_vec_info stmt_info)
> > return res;
> > }
> >
> > +/* If STMT was previously associated with a stmt_vec_info and STMT now
> > resides
> > + at a different address than before (e.g., because STMT is a phi node
> > that has
> > + been resized), update the expected address to match the new one. */
> > +
> > +stmt_vec_info
> > +vec_info::resync_stmt_addr (gimple *stmt)
> > +{
> > + unsigned int uid = gimple_uid (stmt);
> > + if (uid > 0 && uid - 1 < stmt_vec_infos.length ())
> > + {
> > + stmt_vec_info res = stmt_vec_infos[uid - 1];
> > + if (res && res->stmt)
> > + {
> > + res->stmt = stmt;
> > + return res;
> > + }
> > + }
> > + return nullptr;
> > +}
> > +
> > /* If STMT has an associated stmt_vec_info, return that vec_info, otherwise
> > return null. It is safe to call this function on any statement, even if
> > it might not be part of the vectorizable region. */
> > diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> > index 7f69a3f57b4..749a9299d35 100644
> > --- a/gcc/tree-vectorizer.h
> > +++ b/gcc/tree-vectorizer.h
> > @@ -500,6 +500,7 @@ public:
> >
> > stmt_vec_info add_stmt (gimple *);
> > stmt_vec_info add_pattern_stmt (gimple *, stmt_vec_info);
> > + stmt_vec_info resync_stmt_addr (gimple *);
> > stmt_vec_info lookup_stmt (gimple *);
> > stmt_vec_info lookup_def (tree);
> > stmt_vec_info lookup_single_use (tree);
