https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120817
--- Comment #18 from rguenther at suse dot de <rguenther at suse dot de> --- On Mon, 7 Jul 2025, tnfchris at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120817 > > --- Comment #17 from Tamar Christina <tnfchris at gcc dot gnu.org> --- > (In reply to Richard Biener from comment #16) > > No, that cannot be required for correct operation. I think DSE is wrong in > > assessing that the store covers more than 5 bytes. The following fixes it > > for me > > > > diff --git a/gcc/tree-ssa-dse.cc b/gcc/tree-ssa-dse.cc > > index 5ac4280ee36..51a572316cd 100644 > > --- a/gcc/tree-ssa-dse.cc > > +++ b/gcc/tree-ssa-dse.cc > > @@ -181,10 +181,10 @@ initialize_ao_ref_for_dse (gimple *stmt, ao_ref > > *write, bool may_def_ok = false) > > can provide a may-def variant. */ > > if (may_def_ok) > > { > > - ao_ref_init_from_ptr_and_size ( > > - write, gimple_call_arg (stmt, 0), > > - TYPE_SIZE_UNIT ( > > - TREE_TYPE (gimple_call_arg (stmt, > > stored_value_index)))); > > + ao_ref_init_from_ptr_and_range ( > > + write, gimple_call_arg (stmt, 0), true, 0, -1, > > + tree_to_poly_int64 (TYPE_SIZE ( > > + TREE_TYPE (gimple_call_arg (stmt, > > stored_value_index))))); > > return true; > > } > > break; > > > > That's the same as I was suggesting on IRC, the only difference is that I > handled it in the called, since the rang *is* known if the value is a poly > constant. So I think this change is overzealous as it does block vectp_+ > POLY_INT_CST where we do know the offset. It shouldn't block that case, it will still pick up the extra offset and get access to the adjusted base.
