Alex Coplan <alex.cop...@arm.com> writes:
> In r14-5820-ga49befbd2c783e751dc2110b544fe540eb7e33eb I added support to
> RTL-SSA for inserting new insns, which included support for users
> creating new defs.
>
> However, I missed that apply_changes_to_insn needed updating to ensure
> that the new defs actually got inserted into the main def chain. This
> meant that when the aarch64 ldp/stp pass inserted a new stp insn, the
> stp would just get skipped over during subsequent alias analysis, as its
> def never got inserted into the memory def chain. This (unsurprisingly)
> led to wrong code.
>
> This patch fixes the issue by ensuring new user-created defs get
> inserted. I would have preferred to have used a flag internal to the
> defs instead of a separate data structure to keep track of them, but since
> machine_mode increased to 16 bits we're already at 64 bits in access_info,
> and we can't really reuse m_is_temp as the logic in finalize_new_accesses
> requires it to get cleared.
>
> Bootstrapped/regtested as a series on aarch64-linux-gnu, OK for trunk?
>
> Thanks,
> Alex
>
> gcc/ChangeLog:
>
> PR target/113070
> * rtl-ssa.h: Include hash-set.h.
> * rtl-ssa/changes.cc (function_info::finalize_new_accesses): Add
> new_sets parameter and use it to keep track of new user-created sets.
> (function_info::apply_changes_to_insn): Also call add_def on new sets.
> (function_info::change_insns): Add hash_set to keep track of new
> user-created defs. Plumb it through.
> * rtl-ssa/functions.h: Add hash_set parameter to finalize_new_accesses
> and
> apply_changes_to_insn.
> ---
> gcc/rtl-ssa.h | 1 +
> gcc/rtl-ssa/changes.cc | 28 +++++++++++++++++++++-------
> gcc/rtl-ssa/functions.h | 6 ++++--
> 3 files changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/gcc/rtl-ssa.h b/gcc/rtl-ssa.h
> index f0cf656f5ac..17337639ae8 100644
> --- a/gcc/rtl-ssa.h
> +++ b/gcc/rtl-ssa.h
> @@ -50,6 +50,7 @@
> #include "mux-utils.h"
> #include "rtlanal.h"
> #include "cfgbuild.h"
> +#include "hash-set.h"
>
> // Provides the global crtl->ssa.
> #include "memmodel.h"
> diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
> index ce51d6ccd8d..6119ec3535b 100644
> --- a/gcc/rtl-ssa/changes.cc
> +++ b/gcc/rtl-ssa/changes.cc
> @@ -429,7 +429,8 @@ update_insn_in_place (insn_change &change)
> // POS gives the final position of INSN, which hasn't yet been moved into
> // place.
The new parameter should be documented. How about:
// place. NEW_SETS contains the new set_infos that are being added as part
// of this change (as opposed to being moved or repurposed from existing
// instructions).
> void
> -function_info::finalize_new_accesses (insn_change &change, insn_info *pos)
> +function_info::finalize_new_accesses (insn_change &change, insn_info *pos,
> + hash_set<def_info *> &new_sets)
> {
> insn_info *insn = change.insn ();
>
> @@ -465,6 +466,12 @@ function_info::finalize_new_accesses (insn_change
> &change, insn_info *pos)
> // later in case we see a second write to the same resource.
> def_info *perm_def = allocate<set_info> (change.insn (),
> def->resource ());
> +
> + // Keep track of the new set so we remember to add it to the
> + // def chain later.
> + if (new_sets.add (perm_def))
> + gcc_unreachable (); // We shouldn't see duplicates here.
> +
> def->set_last_def (perm_def);
> def = perm_def;
> }
> @@ -647,7 +654,8 @@ function_info::finalize_new_accesses (insn_change
> &change, insn_info *pos)
> // Copy information from CHANGE to its underlying insn_info, given that
> // the insn_info has already been placed appropriately.
Similarly here.
OK with those changes, thanks.
Richard
> void
> -function_info::apply_changes_to_insn (insn_change &change)
> +function_info::apply_changes_to_insn (insn_change &change,
> + hash_set<def_info *> &new_sets)
> {
> insn_info *insn = change.insn ();
> if (change.is_deletion ())
> @@ -659,10 +667,11 @@ function_info::apply_changes_to_insn (insn_change
> &change)
> // Copy the cost.
> insn->set_cost (change.new_cost);
>
> - // Add all clobbers. Sets and call clobbers never move relative to
> - // other definitions, so are OK as-is.
> + // Add all clobbers and newly-created sets. Existing sets and call
> + // clobbers never move relative to other definitions, so are OK as-is.
> for (def_info *def : change.new_defs)
> - if (is_a<clobber_info *> (def) && !def->is_call_clobber ())
> + if ((is_a<clobber_info *> (def) && !def->is_call_clobber ())
> + || (is_a<set_info *> (def) && new_sets.contains (def)))
> add_def (def);
>
> // Add all uses, now that their position is final.
> @@ -793,6 +802,10 @@ function_info::change_insns (array_slice<insn_change *>
> changes)
> placeholders[i] = placeholder;
> }
>
> + // We need to keep track of newly-added sets as these need adding to
> + // the def chain later.
> + hash_set<def_info *> new_sets;
> +
> // 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.
> //
> @@ -806,7 +819,8 @@ function_info::change_insns (array_slice<insn_change *>
> changes)
> insn_info *placeholder = placeholders[i];
> if (!change.is_deletion ())
> finalize_new_accesses (change,
> - placeholder ? placeholder : change.insn ());
> + placeholder ? placeholder : change.insn (),
> + new_sets);
> }
>
> // Remove all definitions that are no longer needed. After the above,
> @@ -861,7 +875,7 @@ function_info::change_insns (array_slice<insn_change *>
> changes)
>
> // Apply the changes to the underlying insn_infos.
> for (insn_change *change : changes)
> - apply_changes_to_insn (*change);
> + apply_changes_to_insn (*change, new_sets);
>
> // Now that the insns and accesses are up to date, add any REG_UNUSED
> notes.
> for (insn_change *change : changes)
> diff --git a/gcc/rtl-ssa/functions.h b/gcc/rtl-ssa/functions.h
> index 962180e27d6..4573453d896 100644
> --- a/gcc/rtl-ssa/functions.h
> +++ b/gcc/rtl-ssa/functions.h
> @@ -299,8 +299,10 @@ private:
> void process_uses_of_deleted_def (set_info *);
> insn_info *add_placeholder_after (insn_info *);
> void possibly_queue_changes (insn_change &);
> - void finalize_new_accesses (insn_change &, insn_info *);
> - void apply_changes_to_insn (insn_change &);
> + void finalize_new_accesses (insn_change &, insn_info *,
> + hash_set<def_info *> &);
> + void apply_changes_to_insn (insn_change &,
> + hash_set<def_info *> &);
>
> void init_function_data ();
> void calculate_potential_phi_regs (build_info &);
