Re: [RFC] aarch64: Split selected LDPs to improve store forwarding

On Sun, Aug 16, 2026 at 8:17 PM huzife <[email protected]> wrote:
>
> A load pair that partially overlaps a recent scalar store can prevent the
> load from using store-to-load forwarding.  Splitting the pair lets the
> overlapping half use the forwarding path.
>
> Add a late AArch64 RTL pass that handles non-writeback SI and DI GPR load
> pairs.  Search a bounded part of the containing basic block for a scalar
> store to either half, and replace the pair only when both scalar loads are
> recognized.  Reject volatile, frame-related and exception-sensitive forms,
> and disable the transformation for size optimization.  Keep the pass off by
> default behind a target parameter while its profitability is evaluated.


I am not sure we want this.  Is this dependent on the micro-arch? Can
you expand on which micro-arch where this helps out?
Also shouldn't instead of a separate pass which undoes what an earlier
pass. Won't it be better to improve the heuristics of ldp_fusion pass
to reject this from happening in the first place for these cases?

>
> gcc/ChangeLog:
>
>         * config.gcc (aarch64*-*-*): Add aarch64-ldp-split.o.
>         * config/aarch64/aarch64-ldp-split.cc: New file.
>         * config/aarch64/aarch64-passes.def: Insert pass_split_ldp_stlf before
>         pass_sched2.
>         * config/aarch64/aarch64-protos.h (make_pass_split_ldp_stlf): Declare.
>         * config/aarch64/aarch64.opt: Add aarch64-split-ldp-stlf parameter.
>         * config/aarch64/t-aarch64 (aarch64-ldp-split.o): New rule.
>         * doc/params.texi (aarch64-split-ldp-stlf): Document.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/aarch64/split-ldp-stlf-1.c: New test.
>         * gcc.target/aarch64/split-ldp-stlf-2.c: New test.
>         * gcc.target/aarch64/split-ldp-stlf-3.c: New test.
>         * gcc.target/aarch64/split-ldp-stlf-4.c: New test.
>         * gcc.target/aarch64/split-ldp-stlf-5.c: New test.
>         * gcc.target/aarch64/split-ldp-stlf-6.c: New test.
>
> Signed-off-by: huzife <[email protected]>
> ---
>  gcc/config.gcc                                |   1 +
>  gcc/config/aarch64/aarch64-ldp-split.cc       | 316 ++++++++++++++++++
>  gcc/config/aarch64/aarch64-passes.def         |   1 +
>  gcc/config/aarch64/aarch64-protos.h           |   1 +
>  gcc/config/aarch64/aarch64.opt                |   5 +
>  gcc/config/aarch64/t-aarch64                  |   6 +
>  gcc/doc/params.texi                           |   8 +
>  .../gcc.target/aarch64/split-ldp-stlf-1.c     |  43 +++
>  .../gcc.target/aarch64/split-ldp-stlf-2.c     |  13 +
>  .../gcc.target/aarch64/split-ldp-stlf-3.c     |  22 ++
>  .../gcc.target/aarch64/split-ldp-stlf-4.c     |  14 +
>  .../gcc.target/aarch64/split-ldp-stlf-5.c     |  13 +
>  .../gcc.target/aarch64/split-ldp-stlf-6.c     |  13 +
>  13 files changed, 456 insertions(+)
>  create mode 100644 gcc/config/aarch64/aarch64-ldp-split.cc
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-1.c
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-2.c
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-3.c
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-4.c
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-5.c
>  create mode 100644 gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-6.c
>
> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index 0477bf22c8a..00aa965f162 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -362,6 +362,7 @@ aarch64*-*-*)
>         extra_objs="${extra_objs} aarch-bti-insert.o"
>         extra_objs="${extra_objs} aarch64-early-ra.o"
>         extra_objs="${extra_objs} aarch64-ldp-fusion.o"
> +       extra_objs="${extra_objs} aarch64-ldp-split.o"
>         extra_objs="${extra_objs} aarch64-sched-dispatch.o"
>         extra_objs="${extra_objs} aarch64-json-tunings-printer.o"
>         extra_objs="${extra_objs} aarch64-json-tunings-parser.o"
> diff --git a/gcc/config/aarch64/aarch64-ldp-split.cc b/gcc/config/aarch64/aarch64-ldp-split.cc
> new file mode 100644
> index 00000000000..a4c2c159529
> --- /dev/null
> +++ b/gcc/config/aarch64/aarch64-ldp-split.cc
> @@ -0,0 +1,316 @@
> +/* Split selected load pairs to improve store-to-load forwarding on AArch64.
> +   Copyright (C) 2026 Free Software Foundation, Inc.
> +
> +   This file is part of GCC.
> +
> +   GCC is free software; you can redistribute it and/or modify it under
> +   the terms of the GNU General Public License as published by the Free
> +   Software Foundation; either version 3, or (at your option) any later
> +   version.
> +
> +   GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +   WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +   for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with GCC; see the file COPYING3.  If not see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#define IN_TARGET_CODE 1
> +
> +#include "config.h"
> +#include "system.h"
> +#include "coretypes.h"
> +#include "backend.h"
> +#include "rtl.h"
> +#include "df.h"
> +#include "memmodel.h"
> +#include "emit-rtl.h"
> +#include "tree-pass.h"
> +#include "insn-attr.h"
> +#include "insn-constants.h"
> +#include "insn-config.h"
> +#include "recog.h"
> +#include "cfgrtl.h"
> +#include "predict.h"
> +
> +namespace {
> +
> +/* A non-writeback GPR load pair that is safe for this pass to split.  */
> +struct ldp_info
> +{
> +  rtx dests[2];
> +  rtx mem;
> +  rtx base;
> +  machine_mode mode;
> +  HOST_WIDE_INT offset;
> +  HOST_WIDE_INT access_size;
> +};
> +
> +/* Return true if REG is a hard general-purpose register in MODE.  */
> +
> +static bool
> +gpr_operand_p (rtx reg, machine_mode mode)
> +{
> +  return (REG_P (reg)
> +         && HARD_REGISTER_P (reg)
> +         && GP_REGNUM_P (REGNO (reg))
> +         && GET_MODE (reg) == mode);
> +}
> +
> +/* Extract the MEM from one half of an AArch64 load pair.  */
> +
> +static rtx
> +extract_ldp_mem (rtx set, rtx dest, int unspec_code)
> +{
> +  if (GET_CODE (set) != SET || !rtx_equal_p (SET_DEST (set), dest))
> +    return NULL_RTX;
> +
> +  rtx src = SET_SRC (set);
> +  if (GET_CODE (src) != UNSPEC
> +      || XINT (src, 1) != unspec_code
> +      || XVECLEN (src, 0) != 1)
> +    return NULL_RTX;
> +
> +  rtx mem = XVECEXP (src, 0, 0);
> +  return MEM_P (mem) ? mem : NULL_RTX;
> +}
> +
> +/* If INSN is an ordinary, non-writeback SI or DI GPR LDP, describe it in
> +   INFO and return true.  Deliberately reject FP/SIMD, TImode, volatile,
> +   frame-related, and EH-sensitive forms.  */
> +
> +static bool
> +extract_ldp (rtx_insn *insn, ldp_info *info)
> +{
> +  if (!NONDEBUG_INSN_P (insn)
> +      || INSN_CODE (insn) < 0
> +      || get_attr_ldpstp (insn) != LDPSTP_LDP
> +      || RTX_FRAME_RELATED_P (insn)
> +      || find_reg_note (insn, REG_EH_REGION, NULL_RTX))
> +    return false;
> +
> +  rtx pattern = PATTERN (insn);
> +  if (GET_CODE (pattern) != PARALLEL || XVECLEN (pattern, 0) != 2)
> +    return false;
> +
> +  rtx sets[2] = { XVECEXP (pattern, 0, 0), XVECEXP (pattern, 0, 1) };
> +  if (GET_CODE (sets[0]) != SET || GET_CODE (sets[1]) != SET)
> +    return false;
> +
> +  info->dests[0] = SET_DEST (sets[0]);
> +  info->dests[1] = SET_DEST (sets[1]);
> +  info->mode = GET_MODE (info->dests[0]);
> +  if ((info->mode != SImode && info->mode != DImode)
> +      || !gpr_operand_p (info->dests[0], info->mode)
> +      || !gpr_operand_p (info->dests[1], info->mode)
> +      || reg_overlap_mentioned_p (info->dests[0], info->dests[1]))
> +    return false;
> +
> +  rtx mem0 = extract_ldp_mem (sets[0], info->dests[0], UNSPEC_LDP_FST);
> +  rtx mem1 = extract_ldp_mem (sets[1], info->dests[1], UNSPEC_LDP_SND);
> +  if (!mem0
> +      || !mem1
> +      || !rtx_equal_p (mem0, mem1)
> +      || MEM_VOLATILE_P (mem0)
> +      || side_effects_p (XEXP (mem0, 0))
> +      || !MEM_SIZE_KNOWN_P (mem0)
> +      || !MEM_SIZE (mem0).is_constant ())
> +    return false;
> +
> +  info->access_size = GET_MODE_SIZE (info->mode).to_constant ();
> +  if (!known_eq (MEM_SIZE (mem0), 2 * info->access_size))
> +    return false;
> +
> +  poly_int64 offset;
> +  info->base = strip_offset (XEXP (mem0, 0), &offset);
> +  if (!REG_P (info->base) || !offset.is_constant (&info->offset))
> +    return false;
> +
> +  info->mem = mem0;
> +  return true;
> +}
> +
> +/* Return true if INSN is a nonvolatile GPR store of one LDP half, using the
> +   same unmodified base as INFO and writing exactly the low or high half.  */
> +
> +static bool
> +forwarding_store_p (rtx_insn *insn, const ldp_info &info)
> +{
> +  if (!NONDEBUG_INSN_P (insn) || RTX_FRAME_RELATED_P (insn))
> +    return false;
> +
> +  rtx set = single_set (insn);
> +  if (!set || !MEM_P (SET_DEST (set)))
> +    return false;
> +
> +  rtx mem = SET_DEST (set);
> +  rtx value = SET_SRC (set);
> +  if (GET_MODE (mem) != info.mode
> +      || !gpr_operand_p (value, info.mode)
> +      || MEM_VOLATILE_P (mem)
> +      || side_effects_p (XEXP (mem, 0))
> +      || !MEM_SIZE_KNOWN_P (mem)
> +      || !known_eq (MEM_SIZE (mem), info.access_size))
> +    return false;
> +
> +  poly_int64 poly_offset;
> +  rtx base = strip_offset (XEXP (mem, 0), &poly_offset);
> +  HOST_WIDE_INT offset;
> +  if (!REG_P (base)
> +      || !rtx_equal_p (base, info.base)
> +      || !poly_offset.is_constant (&offset))
> +    return false;
> +
> +  return (offset == info.offset
> +         || offset == info.offset + info.access_size);
> +}
> +
> +/* Search backwards in the containing basic block for a nearby store that
> +   makes splitting PAIR profitable.  Stop once the base value changes.  */
> +
> +static rtx_insn *
> +find_forwarding_store (rtx_insn *pair, const ldp_info &info)
> +{
> +  basic_block bb = BLOCK_FOR_INSN (pair);
> +  unsigned int distance = 0;
> +  unsigned int max_distance = (unsigned int) aarch64_split_ldp_stlf;
> +
> +  for (rtx_insn *insn = PREV_INSN (pair);
> +       insn && BLOCK_FOR_INSN (insn) == bb;
> +       insn = PREV_INSN (insn))
> +    {
> +      if (!NONDEBUG_INSN_P (insn))
> +       continue;
> +
> +      if (++distance > max_distance)
> +       break;
> +
> +      if (CALL_P (insn) || modified_in_p (info.base, insn))
> +       break;
> +
> +      if (forwarding_store_p (insn, info))
> +       return insn;
> +    }
> +
> +  return NULL;
> +}
> +
> +/* Replace PAIR with two individually-recognized scalar loads.  Load the
> +   non-base destination first when the low destination overlaps the base.  */
> +
> +static bool
> +split_ldp (rtx_insn *pair, const ldp_info &info)
> +{
> +  rtx mems[2] = {
> +    adjust_address_nv (info.mem, info.mode, 0),
> +    adjust_address_nv (info.mem, info.mode, info.access_size)
> +  };
> +
> +  int order[2] = { 0, 1 };
> +  if (reg_overlap_mentioned_p (info.base, info.dests[0]))
> +    std::swap (order[0], order[1]);
> +
> +  start_sequence ();
> +  emit_insn (gen_rtx_SET (info.dests[order[0]], mems[order[0]]));
> +  emit_insn (gen_rtx_SET (info.dests[order[1]], mems[order[1]]));
> +  rtx_insn *seq = get_insns ();
> +  end_sequence ();
> +
> +  unshare_all_rtl_in_chain (seq);
> +  for (rtx_insn *insn = seq; insn; insn = NEXT_INSN (insn))
> +    if (!NONDEBUG_INSN_P (insn) || recog_memoized (insn) < 0)
> +      {
> +       if (dump_file)
> +         fprintf (dump_file,
> +                  "Rejecting LDP %d: scalar replacement is not recognized\n",
> +                  INSN_UID (pair));
> +       return false;
> +      }
> +
> +  if (dump_file)
> +    {
> +      fprintf (dump_file, "Splitting LDP %d into:\n", INSN_UID (pair));
> +      for (rtx_insn *insn = seq; insn; insn = NEXT_INSN (insn))
> +       print_rtl_single (dump_file, insn);
> +    }
> +
> +  emit_insn_before_setloc (seq, pair, INSN_LOCATION (pair));
> +  delete_insn (pair);
> +  return true;
> +}
> +
> +const pass_data pass_data_split_ldp_stlf =
> +{
> +  RTL_PASS, /* type.  */
> +  "split_ldp_stlf", /* name.  */
> +  OPTGROUP_NONE, /* optinfo_flags.  */
> +  TV_MACH_DEP, /* tv_id.  */
> +  0, /* properties_required.  */
> +  0, /* properties_provided.  */
> +  0, /* properties_destroyed.  */
> +  0, /* todo_flags_start.  */
> +  TODO_df_verify | TODO_df_finish, /* todo_flags_finish.  */
> +};
> +
> +class pass_split_ldp_stlf : public rtl_opt_pass
> +{
> +public:
> +  pass_split_ldp_stlf (gcc::context *ctxt)
> +    : rtl_opt_pass (pass_data_split_ldp_stlf, ctxt)
> +  {}
> +
> +  bool gate (function *fn) final override
> +  {
> +    return (optimize >= 1
> +           && !optimize_debug
> +           && reload_completed
> +           && aarch64_split_ldp_stlf
> +           && !optimize_function_for_size_p (fn)
> +           && !fn->can_throw_non_call_exceptions);
> +  }
> +
> +  unsigned int execute (function *fn) final override
> +  {
> +    unsigned int split_count = 0;
> +    basic_block bb;
> +
> +    FOR_EACH_BB_FN (bb, fn)
> +      {
> +       rtx_insn *insn;
> +       rtx_insn *next;
> +       FOR_BB_INSNS_SAFE (bb, insn, next)
> +         {
> +           ldp_info info;
> +           if (!extract_ldp (insn, &info))
> +             continue;
> +
> +           rtx_insn *store = find_forwarding_store (insn, info);
> +           if (!store)
> +             continue;
> +
> +           if (dump_file)
> +             {
> +               fprintf (dump_file, "Found forwarding store for LDP %d:\n",
> +                        INSN_UID (insn));
> +               print_rtl_single (dump_file, store);
> +             }
> +
> +           split_count += split_ldp (insn, info);
> +         }
> +      }
> +
> +    if (dump_file)
> +      fprintf (dump_file, "Split %u LDP instructions\n", split_count);
> +    return 0;
> +  }
> +};
> +
> +} // namespace
> +
> +rtl_opt_pass *
> +make_pass_split_ldp_stlf (gcc::context *ctxt)
> +{
> +  return new pass_split_ldp_stlf (ctxt);
> +}
> diff --git a/gcc/config/aarch64/aarch64-passes.def b/gcc/config/aarch64/aarch64-passes.def
> index 2df7459af92..594348a0532 100644
> --- a/gcc/config/aarch64/aarch64-passes.def
> +++ b/gcc/config/aarch64/aarch64-passes.def
> @@ -26,4 +26,5 @@ INSERT_PASS_BEFORE (pass_late_thread_prologue_and_epilogue, 1, pass_late_track_s
>  INSERT_PASS_BEFORE (pass_shorten_branches, 1, pass_insert_bti);
>  INSERT_PASS_BEFORE (pass_early_remat, 1, pass_ldp_fusion);
>  INSERT_PASS_BEFORE (pass_peephole2, 1, pass_ldp_fusion);
> +INSERT_PASS_BEFORE (pass_sched2, 1, pass_split_ldp_stlf);
>  INSERT_PASS_BEFORE (pass_free_cfg, 1, pass_narrow_gp_writes);
> diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
> index bcc833cfaa1..ec8be386c29 100644
> --- a/gcc/config/aarch64/aarch64-protos.h
> +++ b/gcc/config/aarch64/aarch64-protos.h
> @@ -1268,6 +1268,7 @@ rtl_opt_pass *make_pass_late_track_speculation (gcc::context *);
>  rtl_opt_pass *make_pass_insert_bti (gcc::context *ctxt);
>  rtl_opt_pass *make_pass_switch_pstate_sm (gcc::context *ctxt);
>  rtl_opt_pass *make_pass_ldp_fusion (gcc::context *);
> +rtl_opt_pass *make_pass_split_ldp_stlf (gcc::context *);
>  rtl_opt_pass *make_pass_narrow_gp_writes (gcc::context *);
>
>  poly_uint64 aarch64_regmode_natural_size (machine_mode);
> diff --git a/gcc/config/aarch64/aarch64.opt b/gcc/config/aarch64/aarch64.opt
> index deccc6c8887..21e9500996d 100644
> --- a/gcc/config/aarch64/aarch64.opt
> +++ b/gcc/config/aarch64/aarch64.opt
> @@ -461,6 +461,11 @@ individual writeback accesses where possible.  A value of two means we
>  also try to opportunistically form writeback opportunities by folding in
>  trailing destructive updates of the base register used by a pair.
>
> +-param=aarch64-split-ldp-stlf=
> +Target Joined UInteger Var(aarch64_split_ldp_stlf) Init(0) IntegerRange(0, 32) Param
> +Maximum number of preceding instructions to search when splitting an LDP
> +to improve store-to-load forwarding.  A value of zero disables the pass.
> +
>  -param=aarch64-tag-memory-loop-threshold=
>  Target Joined UInteger Var(aarch64_tag_memory_loop_threshold) Init(10) IntegerRange(0, 65536) Param
>  Param to control the threshold in number of granules beyond which an
> diff --git a/gcc/config/aarch64/t-aarch64 b/gcc/config/aarch64/t-aarch64
> index 3942a1049b9..936540aeb4e 100644
> --- a/gcc/config/aarch64/t-aarch64
> +++ b/gcc/config/aarch64/t-aarch64
> @@ -238,6 +238,12 @@ aarch64-ldp-fusion.o: $(srcdir)/config/aarch64/aarch64-ldp-fusion.cc \
>         $(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
>                 $(srcdir)/config/aarch64/aarch64-ldp-fusion.cc
>
> +aarch64-ldp-split.o: $(srcdir)/config/aarch64/aarch64-ldp-split.cc \
> +    $(CONFIG_H) $(SYSTEM_H) $(CORETYPES_H) $(BACKEND_H) $(RTL_H) $(DF_H) \
> +    $(INSN_ATTR_H) insn-config.h $(RECOG_H) tree-pass.h
> +       $(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
> +               $(srcdir)/config/aarch64/aarch64-ldp-split.cc
> +
>  aarch64-sched-dispatch.o: $(srcdir)/config/aarch64/aarch64-sched-dispatch.cc \
>      $(CONFIG_H) $(SYSTEM_H) $(CORETYPES_H) $(BACKEND_H) $(RTL_H) \
>      $(INSN_ATTR_H) $(REGSET_H) sched-int.h $(DUMPFILE_H) \
> diff --git a/gcc/doc/params.texi b/gcc/doc/params.texi
> index 26b34a59aa9..1ae93ae6c75 100644
> --- a/gcc/doc/params.texi
> +++ b/gcc/doc/params.texi
> @@ -2061,6 +2061,14 @@ accesses where possible.  A value of two means we also try to opportunistically
>  form writeback opportunities by folding in trailing destructive updates of the
>  base register used by a pair.
>
> +@paindex aarch64-split-ldp-stlf
> +@item aarch64-split-ldp-stlf
> +Maximum number of preceding instructions that the AArch64 backend searches
> +for a scalar store that writes one half of a later @code{ldp}.  When such a
> +store is found, the backend can split the @code{ldp} into two scalar loads to
> +improve store-to-load forwarding.  A value of zero, which is the default,
> +disables the transformation.
> +
>  @paindex aarch64-loop-vect-issue-rate-niters
>  @item aarch64-loop-vect-issue-rate-niters
>  The tuning for some AArch64 CPUs tries to take both latencies and issue
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-1.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-1.c
> new file mode 100644
> index 00000000000..ca4ca4821b1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-1.c
> @@ -0,0 +1,43 @@
> +/* { dg-options "-O2 --param=aarch64-split-ldp-stlf=16" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +split_low (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +__attribute__ ((noinline, noclone))
> +long
> +split_high (long *p, long value)
> +{
> +  p[2] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +__attribute__ ((noinline, noclone))
> +int
> +split_low_si (int *p, int value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +extern void consume (long, long);
> +
> +__attribute__ ((noinline, noclone))
> +void
> +split_base_dest_overlap (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  consume (p[1], p[2]);
> +}
> +
> +/* { dg-final { scan-assembler-not {\tldp\t} } } */
> +/* { dg-final { scan-assembler-times {\tldr\t} 8 } } */
> +/* { dg-final { scan-assembler-times {\tldr\tx1, \[x0, 16\]\n\tldr\tx0, \[x0, 8\]} 1 } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-2.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-2.c
> new file mode 100644
> index 00000000000..2ad7e2d5825
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-2.c
> @@ -0,0 +1,13 @@
> +/* { dg-options "-O2" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +disabled_by_default (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +/* { dg-final { scan-assembler-times {\tldp\t} 1 } } */
> +/* { dg-final { scan-assembler-not {\tldr\t} } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-3.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-3.c
> new file mode 100644
> index 00000000000..930ada6836d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-3.c
> @@ -0,0 +1,22 @@
> +/* { dg-options "-O2 --param=aarch64-split-ldp-stlf=16" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +no_overlap (long *p, long value)
> +{
> +  p[4] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +__attribute__ ((noinline, noclone))
> +long
> +wrong_store_width (long *p, int value)
> +{
> +  *(int *) ((char *) p + 8) = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +/* { dg-final { scan-assembler-times {\tldp\t} 2 } } */
> +/* { dg-final { scan-assembler-not {\tldr\t} } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-4.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-4.c
> new file mode 100644
> index 00000000000..3e08bcbea05
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-4.c
> @@ -0,0 +1,14 @@
> +/* { dg-options "-O2 --param=aarch64-split-ldp-stlf=16" } */
> +/* { dg-additional-options "-fnon-call-exceptions" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +preserve_faulting_pair (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +/* { dg-final { scan-assembler-times {\tldp\t} 1 } } */
> +/* { dg-final { scan-assembler-not {\tldr\t} } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-5.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-5.c
> new file mode 100644
> index 00000000000..a19551c4374
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-5.c
> @@ -0,0 +1,13 @@
> +/* { dg-options "-Os --param=aarch64-split-ldp-stlf=16" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +optimize_for_size (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +/* { dg-final { scan-assembler-times {\tldp\t} 1 } } */
> +/* { dg-final { scan-assembler-not {\tldr\t} } } */
> diff --git a/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-6.c b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-6.c
> new file mode 100644
> index 00000000000..bd59fe77b47
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/split-ldp-stlf-6.c
> @@ -0,0 +1,13 @@
> +/* { dg-options "-O2 --param=aarch64-split-ldp-stlf=1" } */
> +
> +__attribute__ ((noinline, noclone))
> +long
> +outside_search_window (long *p, long value)
> +{
> +  p[1] = value;
> +  __asm__ __volatile__ ("" ::: "memory");
> +  return p[1] + p[2];
> +}
> +
> +/* { dg-final { scan-assembler-times {\tldp\t} 1 } } */
> +/* { dg-final { scan-assembler-not {\tldr\t} } } */
> --
> 2.43.0
>