Alex Coplan <alex.cop...@arm.com> writes:
> The next patch in this series exposes an interface for creating new uses
> in RTL-SSA. The intent is that new user-created uses can consume new
> user-created defs in the same change group. This is so that we can
> correctly update uses of memory when inserting a new store pair insn in
> the aarch64 load/store pair fusion pass (the affected uses need to
> consume the new store pair insn).
>
> As it stands, finalize_new_accesses is called as part of the backwards
> insn placement loop within change_insns, but if we want new uses to be
> able to depend on new defs in the same change group, we need
> finalize_new_accesses to be called on earlier insns first. This is so
> that when we process temporary uses and turn them into permanent uses,
> we can follow the last_def link on the temporary def to ensure we end up
> with a permanent use consuming a permanent def.
>
> Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?
>
> Thanks,
> Alex
>
> gcc/ChangeLog:
>
> PR target/113070
> * rtl-ssa/changes.cc (function_info::change_insns): Split out the call
> to finalize_new_accesses from the backwards placement loop, run it
> forwards in a separate loop.
OK, thanks.
Richard
> ---
> gcc/rtl-ssa/changes.cc | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
> index 2fac45ae885..e538b637848 100644
> --- a/gcc/rtl-ssa/changes.cc
> +++ b/gcc/rtl-ssa/changes.cc
> @@ -775,15 +775,26 @@ function_info::change_insns (array_slice<insn_change *>
> changes)
> placeholder = add_placeholder_after (after);
> following_insn = placeholder;
> }
> -
> - // Finalize the new list of accesses for the change. Don't install
> - // them yet, so that we still have access to the old lists below.
> - finalize_new_accesses (change,
> - placeholder ? placeholder : insn);
> }
> placeholders[i] = placeholder;
> }
>
> + // Finalize the new list of accesses for each change. Don't install them
> yet,
> + // so that we still have access to the old lists below.
> + //
> + // Note that we do this forwards instead of in the backwards loop above so
> + // that any new defs being inserted are processed before new uses of those
> + // defs, so that the (initially) temporary uses referring to temporary defs
> + // can be easily updated to become permanent uses referring to permanent
> defs.
> + for (unsigned i = 0; i < changes.size (); i++)
> + {
> + insn_change &change = *changes[i];
> + insn_info *placeholder = placeholders[i];
> + if (!change.is_deletion ())
> + finalize_new_accesses (change,
> + placeholder ? placeholder : change.insn ());
> + }
> +
> // Remove all definitions that are no longer needed. After the above,
> // the only uses of such definitions should be dead phis and now-redundant
> // live-out uses.
