Alex Coplan <alex.cop...@arm.com> writes:
> Currently, rtl_ssa::change_insns requires all new uses and defs to be
> specified explicitly. This turns out to be rather inconvenient for
> forming load pairs in the new aarch64 load pair pass, as the pass has to
> determine which mem def the final load pair consumes, and then obtain or
> create a suitable use (i.e. significant bookkeeping, just to keep the
> RTL-SSA IR consistent). It turns out to be much more convenient to
> allow change_insns to infer which def is consumed and create a suitable
> use of mem itself. This patch does that.
>
> Bootstrapped/regtested as a series on aarch64-linux-gnu, OK for trunk?
>
> gcc/ChangeLog:
>
> * rtl-ssa/changes.cc (function_info::finalize_new_accesses): Add new
> parameter to give final insn position, infer use of mem if it isn't
> specified explicitly.
> (function_info::change_insns): Pass down final insn position to
> finalize_new_accesses.
> * rtl-ssa/functions.h: Add parameter to finalize_new_accesses.
OK, thanks.
Richard
> ---
> gcc/rtl-ssa/changes.cc | 31 ++++++++++++++++++++++++++++---
> gcc/rtl-ssa/functions.h | 2 +-
> 2 files changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
> index c48ddd2463c..523ad60d7d8 100644
> --- a/gcc/rtl-ssa/changes.cc
> +++ b/gcc/rtl-ssa/changes.cc
> @@ -370,8 +370,11 @@ update_insn_in_place (insn_change &change)
> // Finalize the new list of definitions and uses in CHANGE, removing
> // any uses and definitions that are no longer needed, and converting
> // pending clobbers into actual definitions.
> +//
> +// POS gives the final position of INSN, which hasn't yet been moved into
> +// place.
> void
> -function_info::finalize_new_accesses (insn_change &change)
> +function_info::finalize_new_accesses (insn_change &change, insn_info *pos)
> {
> insn_info *insn = change.insn ();
>
> @@ -462,13 +465,34 @@ function_info::finalize_new_accesses (insn_change
> &change)
> // Add (possibly temporary) uses to m_temp_uses for each resource.
> // If there are multiple references to the same resource, aggregate
> // information in the modes and flags.
> + use_info *mem_use = nullptr;
> for (rtx_obj_reference ref : properties.refs ())
> if (ref.is_read ())
> {
> unsigned int regno = ref.regno;
> machine_mode mode = ref.is_reg () ? ref.mode : BLKmode;
> use_info *use = find_access (unshared_uses, ref.regno);
> - gcc_assert (use);
> + if (!use)
> + {
> + // For now, we only support inferring uses of mem.
> + gcc_assert (regno == MEM_REGNO);
> +
> + if (mem_use)
> + {
> + mem_use->record_reference (ref, false);
> + continue;
> + }
> +
> + resource_info resource { mode, regno };
> + auto def = find_def (resource, pos).prev_def (pos);
> + auto set = safe_dyn_cast <set_info *> (def);
> + gcc_assert (set);
> + mem_use = allocate<use_info> (insn, resource, set);
> + mem_use->record_reference (ref, true);
> + m_temp_uses.safe_push (mem_use);
> + continue;
> + }
> +
> if (use->m_has_been_superceded)
> {
> // This is the first reference to the resource.
> @@ -656,7 +680,8 @@ function_info::change_insns (array_slice<insn_change *>
> changes)
>
> // 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);
> + finalize_new_accesses (change,
> + placeholder ? placeholder : insn);
> }
> placeholders[i] = placeholder;
> }
> diff --git a/gcc/rtl-ssa/functions.h b/gcc/rtl-ssa/functions.h
> index d7da9774213..73690a0e63b 100644
> --- a/gcc/rtl-ssa/functions.h
> +++ b/gcc/rtl-ssa/functions.h
> @@ -265,7 +265,7 @@ private:
>
> insn_info *add_placeholder_after (insn_info *);
> void possibly_queue_changes (insn_change &);
> - void finalize_new_accesses (insn_change &);
> + void finalize_new_accesses (insn_change &, insn_info *);
> void apply_changes_to_insn (insn_change &);
>
> void init_function_data ();
