On Mon, Apr 26, 2021 at 12:21 AM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Fri, Apr 23, 2021 at 09:12:10AM +0200, Richard Biener wrote:
> > On Fri, Apr 23, 2021 at 1:35 AM H.J. Lu via Gcc-patches
> > <gcc-patches@gcc.gnu.org> wrote:
> > >
> > > For op_by_pieces operations between two areas of memory on non-strict
> > > alignment target, add -foverlap-op-by-pieces=[off|on|max-memset] to
> > > generate overlapping operations to minimize number of operations if it
> > > is not a stack push which must not overlap.
> > >
> > > When operating on LENGTH bytes of memory, -foverlap-op-by-pieces=on
> > > starts with the widest usable integer size, MAX_SIZE, for LENGTH bytes
> > > and finishes with the smallest usable integer size, MIN_SIZE, for the
> > > remaining bytes where MAX_SIZE >= MIN_SIZE.  If MIN_SIZE > the remaining
> > > bytes, the last operation is performed on MIN_SIZE bytes of overlapping
> > > memory from the previous operation.
> > >
> > > For memset with non-zero byte, -foverlap-op-by-pieces=max-memset generates
> > > an overlapping fill with MAX_SIZE if the number of the remaining bytes is
> > > greater than one.
> > >
> > > Tested on Linux/x86-64 with both -foverlap-op-by-pieces enabled and
> > > disabled by default.
> >
> > Neither the user documentation nor the patch description tells me what
> > "generate overlapping operations" does.  I _suspect_ it's doing an
> > offset adjusted read/write of the last piece of a memory region to
> > avoid doing more than one smaller operations.  Thus for a region
> > of size 7 and 4-byte granular ops you'd do operations at
> > offset 0 and 3 rather than one at 0, a two-byte at offset 4 and
> > a one-byte at offset 7.
>
> That is correct.
>
> >
> > When the tail is of power-of-two size you still generate non-overlapping
> > ops?
>
> No.
>
> >
> > For memmove there's a correctness issue so you have to make sure
> > to first load the last two ops before performing the stores which
> > increases register pressure.
>
> I believe memmove is handled correctly.
>
> >
> > I'm not sure we want a -f option to control this - not all targets will
> > be able to support this.  So I'd use a target hook or rather extend
> > the existing use_by_pieces_infrastructure_p hook with an alternate
> > return (some flags bitmask I guess).  We do have one extra
> > target hook, compare_by_pieces_branch_ratio, so by that using
> > an alternate hook might be also OK.
>
> Fixed.
>
> >
> > Adding a -m option in targets that want this user-controllable would
> > be OK of course.
> >
>
> I can add a -m option to control if neeed.
>
> Here is the v2 patch.  Changes are:
>
> 1. Added a target hook, TARGET_OVERLAP_OP_BY_PIECES_P.
> 2. Added a pointer argument to pieces_addr::adjust to pass the RTL
> information from the previous iteraton to m_constfn.
> 3. Updated builtin_memset_read_str and builtin_memset_gen_str to
> generate the new RTL from the previous RTL info.
>
> OK for master branch?
>
> Thanks.
>
> H.J.
> ----
> Add an overlap_op_by_pieces_p target hook for op_by_pieces operations
> between two areas of memory to generate one offset adjusted operation
> in the smallest integer mode for the remaining bytes on the last piece
> operation of a memory region to avoid doing more than one smaller
> operations.
>
> Pass the RTL information from the previous iteration to m_constfn in
> op_by_pieces operation so that builtin_memset_[read|gen]_str can
> generate the new RTL from the previous RTL.
>
> Tested on Linux/x86-64.
>
> gcc/
>
>         PR middl-end/90773
>         * builtins.c (builtin_memcpy_read_str): Add a dummy argument.
>         (builtin_strncpy_read_str): Likewise.
>         (builtin_memset_read_str): Add an argument for the previous RTL
>         information and generate the new RTL from the previous RTL info.
>         (builtin_memset_gen_str): Likewise.
>         * builtins.h (builtin_strncpy_read_str): Update the prototype.
>         (builtin_memset_read_str): Likewise.
>         * expr.c (by_pieces_ninsns): If targetm.overlap_op_by_pieces_p()
>         returns true, round up size and alignment to the widest integer
>         mode for maximum size.
>         (pieces_addr::adjust): Add a pointer to by_pieces_prev argument
>         and pass it to m_constfn.
>         (op_by_pieces_d): Add get_usable_mode, m_push and
>         m_overlap_op_by_pieces.
>         (op_by_pieces_d::op_by_pieces_d): Add a bool argument to
>         initialize m_push.  Initialize m_overlap_op_by_pieces with
>         targetm.overlap_op_by_pieces_p ().
>         (op_by_pieces_d::get_usable_mode): New.
>         (op_by_pieces_d::run): Use get_usable_mode to get the largest
>         usable integer mode, pass the previous info to pieces_addr::adjust
>         and generate overlapping operations if m_overlap_op_by_pieces is
>         true.
>         (PUSHG_P): New.
>         (move_by_pieces_d::move_by_pieces_d): Updated for op_by_pieces_d
>         change.
>         (store_by_pieces_d::store_by_pieces_d): Updated for op_by_pieces_d
>         change.
>         (can_store_by_pieces): Use by_pieces_constfn on constfun.
>         (store_by_pieces): Use by_pieces_constfn on constfun.  Updated
>         for op_by_pieces_d change.
>         (clear_by_pieces_1): Add a dummy argument.
>         (clear_by_pieces): Updated for op_by_pieces_d change.
>         (compare_by_pieces_d::compare_by_pieces_d): Likewise.
>         (string_cst_read_str): Add a dummy argument.
>         * expr.h (by_pieces_constfn): Add a dummy argument.
>         (by_pieces_prev): New.
>         * target.def (overlap_op_by_pieces_p): New target hook.
>         * config/i386/i386.c (TARGET_OVERLAP_OP_BY_PIECES_P): New.
>         * doc/tm.texi.in: Add TARGET_OVERLAP_OP_BY_PIECES_P.
>         * doc/tm.texi: Regenerated.
>
> gcc/testsuite/
>
>         PR middl-end/90773
>         * g++.dg/pr90773-1.h: New test.
>         * g++.dg/pr90773-1a.C: Likewise.
>         * g++.dg/pr90773-1b.C: Likewise.
>         * g++.dg/pr90773-1c.C: Likewise.
>         * g++.dg/pr90773-1d.C: Likewise.
>         * gcc.target/i386/pr90773-1.c: Likewise.
>         * gcc.target/i386/pr90773-2.c: Likewise.
>         * gcc.target/i386/pr90773-3.c: Likewise.
>         * gcc.target/i386/pr90773-4.c: Likewise.
>         * gcc.target/i386/pr90773-5.c: Likewise.
>         * gcc.target/i386/pr90773-6.c: Likewise.
>         * gcc.target/i386/pr90773-7.c: Likewise.
>         * gcc.target/i386/pr90773-8.c: Likewise.
>         * gcc.target/i386/pr90773-9.c: Likewise.
>         * gcc.target/i386/pr90773-10.c: Likewise.
>         * gcc.target/i386/pr90773-11.c: Likewise.
>         * gcc.target/i386/pr90773-12.c: Likewise.
>         * gcc.target/i386/pr90773-13.c: Likewise.
>         * gcc.target/i386/pr90773-14.c: Likewise.
> ---
>  gcc/builtins.c                             |  47 +++++-
>  gcc/builtins.h                             |   6 +-
>  gcc/config/i386/i386.c                     |   3 +
>  gcc/doc/tm.texi                            |   7 +
>  gcc/doc/tm.texi.in                         |   2 +
>  gcc/expr.c                                 | 171 ++++++++++++++++-----
>  gcc/expr.h                                 |  10 +-
>  gcc/target.def                             |   9 ++
>  gcc/testsuite/g++.dg/pr90773-1.h           |  14 ++
>  gcc/testsuite/g++.dg/pr90773-1a.C          |  13 ++
>  gcc/testsuite/g++.dg/pr90773-1b.C          |   5 +
>  gcc/testsuite/g++.dg/pr90773-1c.C          |   5 +
>  gcc/testsuite/g++.dg/pr90773-1d.C          |  19 +++
>  gcc/testsuite/gcc.target/i386/pr90773-1.c  |  17 ++
>  gcc/testsuite/gcc.target/i386/pr90773-10.c |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-11.c |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-12.c |  11 ++
>  gcc/testsuite/gcc.target/i386/pr90773-13.c |  11 ++
>  gcc/testsuite/gcc.target/i386/pr90773-14.c |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-2.c  |  20 +++
>  gcc/testsuite/gcc.target/i386/pr90773-3.c  |  23 +++
>  gcc/testsuite/gcc.target/i386/pr90773-4.c  |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-5.c  |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-6.c  |  11 ++
>  gcc/testsuite/gcc.target/i386/pr90773-7.c  |  11 ++
>  gcc/testsuite/gcc.target/i386/pr90773-8.c  |  13 ++
>  gcc/testsuite/gcc.target/i386/pr90773-9.c  |  13 ++
>  27 files changed, 457 insertions(+), 49 deletions(-)
>  create mode 100644 gcc/testsuite/g++.dg/pr90773-1.h
>  create mode 100644 gcc/testsuite/g++.dg/pr90773-1a.C
>  create mode 100644 gcc/testsuite/g++.dg/pr90773-1b.C
>  create mode 100644 gcc/testsuite/g++.dg/pr90773-1c.C
>  create mode 100644 gcc/testsuite/g++.dg/pr90773-1d.C
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-1.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-10.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-11.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-12.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-13.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-14.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-2.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-3.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-4.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-5.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-6.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-7.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-8.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr90773-9.c
>
> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index 8c5324bf7de..efb449f6c22 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -128,7 +128,6 @@ static rtx expand_builtin_va_copy (tree);
>  static rtx inline_expand_builtin_bytecmp (tree, rtx);
>  static rtx expand_builtin_strcmp (tree, rtx);
>  static rtx expand_builtin_strncmp (tree, rtx, machine_mode);
> -static rtx builtin_memcpy_read_str (void *, HOST_WIDE_INT, scalar_int_mode);
>  static rtx expand_builtin_memchr (tree, rtx);
>  static rtx expand_builtin_memcpy (tree, rtx);
>  static rtx expand_builtin_memory_copy_args (tree dest, tree src, tree len,
> @@ -145,7 +144,6 @@ static rtx expand_builtin_stpcpy (tree, rtx, 
> machine_mode);
>  static rtx expand_builtin_stpncpy (tree, rtx);
>  static rtx expand_builtin_strncat (tree, rtx);
>  static rtx expand_builtin_strncpy (tree, rtx);
> -static rtx builtin_memset_gen_str (void *, HOST_WIDE_INT, scalar_int_mode);
>  static rtx expand_builtin_memset (tree, rtx, machine_mode);
>  static rtx expand_builtin_memset_args (tree, tree, tree, rtx, machine_mode, 
> tree);
>  static rtx expand_builtin_bzero (tree);
> @@ -3860,7 +3858,7 @@ expand_builtin_strnlen (tree exp, rtx target, 
> machine_mode target_mode)
>     a target constant.  */
>
>  static rtx
> -builtin_memcpy_read_str (void *data, HOST_WIDE_INT offset,
> +builtin_memcpy_read_str (void *data, void *, HOST_WIDE_INT offset,
>                          scalar_int_mode mode)
>  {
>    /* The REPresentation pointed to by DATA need not be a nul-terminated
> @@ -6373,7 +6371,7 @@ expand_builtin_stpncpy (tree exp, rtx)
>     constant.  */
>
>  rtx
> -builtin_strncpy_read_str (void *data, HOST_WIDE_INT offset,
> +builtin_strncpy_read_str (void *data, void *, HOST_WIDE_INT offset,
>                           scalar_int_mode mode)
>  {
>    const char *str = (const char *) data;
> @@ -6584,12 +6582,33 @@ expand_builtin_strncpy (tree exp, rtx target)
>
>  /* Callback routine for store_by_pieces.  Read GET_MODE_BITSIZE (MODE)
>     bytes from constant string DATA + OFFSET and return it as target
> -   constant.  */
> +   constant.  If PREV isn't nullptr, it has the RTL info from the
> +   previous iteration.  */
>
>  rtx
> -builtin_memset_read_str (void *data, HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> +builtin_memset_read_str (void *data, void *prevp,
> +                        HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
>                          scalar_int_mode mode)
>  {
> +  by_pieces_prev *prev = (by_pieces_prev *) prevp;
> +  if (prev != nullptr && prev->data != nullptr)
> +    {
> +      /* Use the previous data in the same mode.  */
> +      if (prev->mode == mode)
> +       return prev->data;
> +
> +      /* Truncate the previous constant integer to a const_wide_int in
> +        MODE.  */
> +      if (!CONST_SCALAR_INT_P (prev->data))
> +       gcc_unreachable ();
> +
> +      rtx_mode_t op = rtx_mode_t (prev->data, prev->mode);
> +      wide_int result = wide_int::from (op,
> +                                       GET_MODE_PRECISION (prev->mode),
> +                                       UNSIGNED);
> +      return immed_wide_int_const (result, mode);

Isn't this premature optimization?  The original code should arrive at the
very same CONST_INT, no? ...

> +    }
> +
>    const char *c = (const char *) data;
>    char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
>
> @@ -6601,16 +6620,28 @@ builtin_memset_read_str (void *data, HOST_WIDE_INT 
> offset ATTRIBUTE_UNUSED,
>  /* Callback routine for store_by_pieces.  Return the RTL of a register
>     containing GET_MODE_SIZE (MODE) consecutive copies of the unsigned
>     char value given in the RTL register data.  For example, if mode is
> -   4 bytes wide, return the RTL for 0x01010101*data.  */
> +   4 bytes wide, return the RTL for 0x01010101*data.  If PREV isn't
> +   nullptr, it has the RTL info from the previous iteration.  */
>
>  static rtx
> -builtin_memset_gen_str (void *data, HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> +builtin_memset_gen_str (void *data, void *prevp,
> +                       HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
>                         scalar_int_mode mode)
>  {
>    rtx target, coeff;
>    size_t size;
>    char *p;
>
> +  by_pieces_prev *prev = (by_pieces_prev *) prevp;
> +  if (prev != nullptr && prev->data != nullptr)
> +    {
> +      /* Use the previous data in the same mode.  */
> +      if (prev->mode == mode)
> +       return prev->data;
> +
> +      return simplify_gen_subreg (mode, prev->data, prev->mode, 0);
> +    }
> +

... compared to here where CSE might have difficulties creating the very
same subreg.

>    size = GET_MODE_SIZE (mode);
>    if (size == 1)
>      return (rtx) data;
> diff --git a/gcc/builtins.h b/gcc/builtins.h
> index 307a20fbadb..e71f40c300a 100644
> --- a/gcc/builtins.h
> +++ b/gcc/builtins.h
> @@ -110,8 +110,10 @@ extern void expand_builtin_update_setjmp_buf (rtx);
>  extern tree mathfn_built_in (tree, enum built_in_function fn);
>  extern tree mathfn_built_in (tree, combined_fn);
>  extern tree mathfn_built_in_type (combined_fn);
> -extern rtx builtin_strncpy_read_str (void *, HOST_WIDE_INT, scalar_int_mode);
> -extern rtx builtin_memset_read_str (void *, HOST_WIDE_INT, scalar_int_mode);
> +extern rtx builtin_strncpy_read_str (void *, void *, HOST_WIDE_INT,
> +                                    scalar_int_mode);
> +extern rtx builtin_memset_read_str (void *, void *, HOST_WIDE_INT,
> +                                   scalar_int_mode);
>  extern rtx expand_builtin_saveregs (void);
>  extern tree std_build_builtin_va_list (void);
>  extern tree std_fn_abi_va_list (tree);
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index adcef1e98bf..68f33f96f5a 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -23538,6 +23538,9 @@ ix86_run_selftests (void)
>  #undef TARGET_ADDRESS_COST
>  #define TARGET_ADDRESS_COST ix86_address_cost
>
> +#undef TARGET_OVERLAP_OP_BY_PIECES_P
> +#define TARGET_OVERLAP_OP_BY_PIECES_P hook_bool_void_true
> +
>  #undef TARGET_FLAGS_REGNUM
>  #define TARGET_FLAGS_REGNUM FLAGS_REG
>  #undef TARGET_FIXED_CONDITION_CODE_REGS
> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> index 823f85ba9ab..8631435f271 100644
> --- a/gcc/doc/tm.texi
> +++ b/gcc/doc/tm.texi
> @@ -6758,6 +6758,13 @@ in code size, for example where the number of insns 
> emitted to perform a
>  move would be greater than that of a library call.
>  @end deftypefn
>
> +@deftypefn {Target Hook} bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
> +This target hook should return true if when the @code{by_pieces}
> +infrastructure is used, an offset adjusted memory operation in the

.. offset adjusted unaligned memory operation ..

might be worth noting that the access will be unaligned.

> +smallest integer mode for the last piece operation of a memory region
> +can be generated to avoid doing more than one smaller operations.
> +@end deftypefn
> +
>  @deftypefn {Target Hook} int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO 
> (machine_mode @var{mode})
>  When expanding a block comparison in MODE, gcc can try to reduce the
>  number of branches at the expense of more memory operations.  This hook
> diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> index 2321a5fc4e0..4ac3452278e 100644
> --- a/gcc/doc/tm.texi.in
> +++ b/gcc/doc/tm.texi.in
> @@ -4586,6 +4586,8 @@ If you don't define this, a reasonable default is used.
>
>  @hook TARGET_USE_BY_PIECES_INFRASTRUCTURE_P
>
> +@hook TARGET_OVERLAP_OP_BY_PIECES_P
> +
>  @hook TARGET_COMPARE_BY_PIECES_BRANCH_RATIO
>
>  @defmac MOVE_MAX_PIECES
> diff --git a/gcc/expr.c b/gcc/expr.c
> index a0e19465965..b5b96ea1185 100644
> --- a/gcc/expr.c
> +++ b/gcc/expr.c
> @@ -815,12 +815,27 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l, unsigned 
> int align,
>                   unsigned int max_size, by_pieces_operation op)
>  {
>    unsigned HOST_WIDE_INT n_insns = 0;
> +  scalar_int_mode mode;
> +
> +  if (targetm.overlap_op_by_pieces_p () && op != COMPARE_BY_PIECES)
> +    {
> +      /* NB: Round up L and ALIGN to the widest integer mode for
> +        MAX_SIZE.  */
> +      mode = widest_int_mode_for_size (max_size);
> +      if (optab_handler (mov_optab, mode) != CODE_FOR_nothing)
> +       {
> +         unsigned HOST_WIDE_INT up = ROUND_UP (l, GET_MODE_SIZE (mode));
> +         if (up > l)
> +           l = up;
> +         align = GET_MODE_ALIGNMENT (mode);

why's this necessary?  It looks like alignment_for_piecewise_move will
properly honor slow_unaligned_access which better should be false for
overlap_op_by_pieces

> +       }
> +    }
>
>    align = alignment_for_piecewise_move (MOVE_MAX_PIECES, align);
>
>    while (max_size > 1 && l > 0)
>      {
> -      scalar_int_mode mode = widest_int_mode_for_size (max_size);
> +      mode = widest_int_mode_for_size (max_size);
>        enum insn_code icode;
>
>        unsigned int modesize = GET_MODE_SIZE (mode);
> @@ -888,7 +903,8 @@ class pieces_addr
>    void *m_cfndata;
>  public:
>    pieces_addr (rtx, bool, by_pieces_constfn, void *);
> -  rtx adjust (scalar_int_mode, HOST_WIDE_INT);
> +  rtx adjust (scalar_int_mode, HOST_WIDE_INT,
> +             by_pieces_prev * = nullptr);
>    void increment_address (HOST_WIDE_INT);
>    void maybe_predec (HOST_WIDE_INT);
>    void maybe_postinc (HOST_WIDE_INT);
> @@ -990,10 +1006,12 @@ pieces_addr::decide_autoinc (machine_mode ARG_UNUSED 
> (mode), bool reverse,
>     but we still modify the MEM's properties.  */
>
>  rtx
> -pieces_addr::adjust (scalar_int_mode mode, HOST_WIDE_INT offset)
> +pieces_addr::adjust (scalar_int_mode mode, HOST_WIDE_INT offset,
> +                    by_pieces_prev *prev)
>  {
>    if (m_constfn)
> -    return m_constfn (m_cfndata, offset, mode);
> +    /* Pass the previous data to m_constfn.  */
> +    return m_constfn (m_cfndata, prev, offset, mode);
>    if (m_obj == NULL_RTX)
>      return NULL_RTX;
>    if (m_auto)
> @@ -1041,6 +1059,9 @@ pieces_addr::maybe_postinc (HOST_WIDE_INT size)
>
>  class op_by_pieces_d
>  {
> + private:
> +  scalar_int_mode get_usable_mode (scalar_int_mode mode, unsigned int);
> +
>   protected:
>    pieces_addr m_to, m_from;
>    unsigned HOST_WIDE_INT m_len;
> @@ -1048,6 +1069,10 @@ class op_by_pieces_d
>    unsigned int m_align;
>    unsigned int m_max_size;
>    bool m_reverse;
> +  /* True if this is a stack push.  */
> +  bool m_push;
> +  /* True if targetm.overlap_op_by_pieces_p () returns true.  */
> +  bool m_overlap_op_by_pieces;
>
>    /* Virtual functions, overriden by derived classes for the specific
>       operation.  */
> @@ -1059,7 +1084,7 @@ class op_by_pieces_d
>
>   public:
>    op_by_pieces_d (rtx, bool, rtx, bool, by_pieces_constfn, void *,
> -                 unsigned HOST_WIDE_INT, unsigned int);
> +                 unsigned HOST_WIDE_INT, unsigned int, bool);
>    void run ();
>  };
>
> @@ -1074,10 +1099,11 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
>                                 by_pieces_constfn from_cfn,
>                                 void *from_cfn_data,
>                                 unsigned HOST_WIDE_INT len,
> -                               unsigned int align)
> +                               unsigned int align, bool push)
>    : m_to (to, to_load, NULL, NULL),
>      m_from (from, from_load, from_cfn, from_cfn_data),
> -    m_len (len), m_max_size (MOVE_MAX_PIECES + 1)
> +    m_len (len), m_max_size (MOVE_MAX_PIECES + 1),
> +    m_push (push)
>  {
>    int toi = m_to.get_addr_inc ();
>    int fromi = m_from.get_addr_inc ();
> @@ -1106,6 +1132,27 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
>
>    align = alignment_for_piecewise_move (MOVE_MAX_PIECES, align);
>    m_align = align;
> +
> +  m_overlap_op_by_pieces = targetm.overlap_op_by_pieces_p ();
> +}
> +
> +/* This function returns the largest usable integer mode for LEN bytes
> +   whose size is no bigger than size of MODE.  */
> +
> +scalar_int_mode
> +op_by_pieces_d::get_usable_mode (scalar_int_mode mode, unsigned int len)
> +{
> +  unsigned int size;
> +  do
> +    {
> +      size = GET_MODE_SIZE (mode);
> +      if (len >= size && prepare_mode (mode, m_align))
> +       break;
> +      /* NB: widest_int_mode_for_size checks SIZE > 1.  */
> +      mode = widest_int_mode_for_size (size);
> +    }
> +  while (1);
> +  return mode;
>  }
>
>  /* This function contains the main loop used for expanding a block
> @@ -1116,42 +1163,80 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
>  void
>  op_by_pieces_d::run ()
>  {
> -  while (m_max_size > 1 && m_len > 0)
> +  if (m_len == 0)
> +    return;
> +
> +  /* NB: widest_int_mode_for_size checks M_MAX_SIZE > 1.  */
> +  scalar_int_mode mode = widest_int_mode_for_size (m_max_size);
> +  mode = get_usable_mode (mode, m_len);
> +
> +  by_pieces_prev to_prev = { nullptr, mode };
> +  by_pieces_prev from_prev = { nullptr, mode };
> +
> +  do

splitting out the refactoring from a while to a do-while loop might ease review.

Otherwise it looks OK - looks like my memmove concern is moot since
by-pieces isn't used for memmove anyway.

Richard.

>      {
> -      scalar_int_mode mode = widest_int_mode_for_size (m_max_size);
> +      unsigned int size = GET_MODE_SIZE (mode);
> +      rtx to1 = NULL_RTX, from1;
>
> -      if (prepare_mode (mode, m_align))
> +      while (m_len >= size)
>         {
> -         unsigned int size = GET_MODE_SIZE (mode);
> -         rtx to1 = NULL_RTX, from1;
> +         if (m_reverse)
> +           m_offset -= size;
>
> -         while (m_len >= size)
> -           {
> -             if (m_reverse)
> -               m_offset -= size;
> +         to1 = m_to.adjust (mode, m_offset, &to_prev);
> +         to_prev.data = to1;
> +         to_prev.mode = mode;
> +         from1 = m_from.adjust (mode, m_offset, &from_prev);
> +         from_prev.data = from1;
> +         from_prev.mode = mode;
>
> -             to1 = m_to.adjust (mode, m_offset);
> -             from1 = m_from.adjust (mode, m_offset);
> +         m_to.maybe_predec (-(HOST_WIDE_INT)size);
> +         m_from.maybe_predec (-(HOST_WIDE_INT)size);
>
> -             m_to.maybe_predec (-(HOST_WIDE_INT)size);
> -             m_from.maybe_predec (-(HOST_WIDE_INT)size);
> +         generate (to1, from1, mode);
>
> -             generate (to1, from1, mode);
> +         m_to.maybe_postinc (size);
> +         m_from.maybe_postinc (size);
>
> -             m_to.maybe_postinc (size);
> -             m_from.maybe_postinc (size);
> +         if (!m_reverse)
> +           m_offset += size;
>
> -             if (!m_reverse)
> -               m_offset += size;
> +         m_len -= size;
> +       }
>
> -             m_len -= size;
> -           }
> +      finish_mode (mode);
>
> -         finish_mode (mode);
> -       }
> +      if (m_len == 0)
> +       return;
>
> -      m_max_size = GET_MODE_SIZE (mode);
> +      if (!m_push && m_overlap_op_by_pieces)
> +       {
> +         /* NB: Generate overlapping operations if it is not a stack
> +            push since stack push must not overlap.  Get the smallest
> +            integer mode for M_LEN bytes.  */
> +         mode = smallest_int_mode_for_size (m_len * BITS_PER_UNIT);
> +         mode = get_usable_mode (mode, GET_MODE_SIZE (mode));
> +         int gap = GET_MODE_SIZE (mode) - m_len;
> +         if (gap > 0)
> +           {
> +             /* If size of MODE > M_LEN, generate the last operation
> +                in MODE for the remaining bytes with ovelapping memory
> +                from the previois operation.  */
> +             if (m_reverse)
> +               m_offset += gap;
> +             else
> +               m_offset -= gap;
> +             m_len += gap;
> +           }
> +       }
> +      else
> +       {
> +         /* NB: widest_int_mode_for_size checks SIZE > 1.  */
> +         mode = widest_int_mode_for_size (size);
> +         mode = get_usable_mode (mode, m_len);
> +       }
>      }
> +  while (1);
>
>    /* The code above should have handled everything.  */
>    gcc_assert (!m_len);
> @@ -1160,6 +1245,12 @@ op_by_pieces_d::run ()
>  /* Derived class from op_by_pieces_d, providing support for block move
>     operations.  */
>
> +#ifdef PUSH_ROUNDING
> +#define PUSHG_P(to)  ((to) == nullptr)
> +#else
> +#define PUSHG_P(to)  false
> +#endif
> +
>  class move_by_pieces_d : public op_by_pieces_d
>  {
>    insn_gen_fn m_gen_fun;
> @@ -1169,7 +1260,8 @@ class move_by_pieces_d : public op_by_pieces_d
>   public:
>    move_by_pieces_d (rtx to, rtx from, unsigned HOST_WIDE_INT len,
>                     unsigned int align)
> -    : op_by_pieces_d (to, false, from, true, NULL, NULL, len, align)
> +    : op_by_pieces_d (to, false, from, true, NULL, NULL, len, align,
> +                     PUSHG_P (to))
>    {
>    }
>    rtx finish_retmode (memop_ret);
> @@ -1264,7 +1356,8 @@ class store_by_pieces_d : public op_by_pieces_d
>   public:
>    store_by_pieces_d (rtx to, by_pieces_constfn cfn, void *cfn_data,
>                      unsigned HOST_WIDE_INT len, unsigned int align)
> -    : op_by_pieces_d (to, false, NULL_RTX, true, cfn, cfn_data, len, align)
> +    : op_by_pieces_d (to, false, NULL_RTX, true, cfn, cfn_data, len,
> +                     align, false)
>    {
>    }
>    rtx finish_retmode (memop_ret);
> @@ -1319,7 +1412,7 @@ store_by_pieces_d::finish_retmode (memop_ret retmode)
>
>  int
>  can_store_by_pieces (unsigned HOST_WIDE_INT len,
> -                    rtx (*constfun) (void *, HOST_WIDE_INT, scalar_int_mode),
> +                    by_pieces_constfn constfun,
>                      void *constfundata, unsigned int align, bool memsetp)
>  {
>    unsigned HOST_WIDE_INT l;
> @@ -1366,7 +1459,7 @@ can_store_by_pieces (unsigned HOST_WIDE_INT len,
>                   if (reverse)
>                     offset -= size;
>
> -                 cst = (*constfun) (constfundata, offset, mode);
> +                 cst = (*constfun) (constfundata, nullptr, offset, mode);
>                   if (!targetm.legitimate_constant_p (mode, cst))
>                     return 0;
>
> @@ -1396,7 +1489,7 @@ can_store_by_pieces (unsigned HOST_WIDE_INT len,
>
>  rtx
>  store_by_pieces (rtx to, unsigned HOST_WIDE_INT len,
> -                rtx (*constfun) (void *, HOST_WIDE_INT, scalar_int_mode),
> +                by_pieces_constfn constfun,
>                  void *constfundata, unsigned int align, bool memsetp,
>                  memop_ret retmode)
>  {
> @@ -1424,7 +1517,7 @@ store_by_pieces (rtx to, unsigned HOST_WIDE_INT len,
>     Return const0_rtx unconditionally.  */
>
>  static rtx
> -clear_by_pieces_1 (void *, HOST_WIDE_INT, scalar_int_mode)
> +clear_by_pieces_1 (void *, void *, HOST_WIDE_INT, scalar_int_mode)
>  {
>    return const0_rtx;
>  }
> @@ -1460,7 +1553,8 @@ class compare_by_pieces_d : public op_by_pieces_d
>    compare_by_pieces_d (rtx op0, rtx op1, by_pieces_constfn op1_cfn,
>                        void *op1_cfn_data, HOST_WIDE_INT len, int align,
>                        rtx_code_label *fail_label)
> -    : op_by_pieces_d (op0, true, op1, true, op1_cfn, op1_cfn_data, len, 
> align)
> +    : op_by_pieces_d (op0, true, op1, true, op1_cfn, op1_cfn_data, len,
> +                     align, false)
>    {
>      m_fail_label = fail_label;
>    }
> @@ -5646,7 +5740,8 @@ emit_storent_insn (rtx to, rtx from)
>  /* Helper function for store_expr storing of STRING_CST.  */
>
>  static rtx
> -string_cst_read_str (void *data, HOST_WIDE_INT offset, scalar_int_mode mode)
> +string_cst_read_str (void *data, void *, HOST_WIDE_INT offset,
> +                    scalar_int_mode mode)
>  {
>    tree str = (tree) data;
>
> diff --git a/gcc/expr.h b/gcc/expr.h
> index 1f0177a4cfa..9a2736f69fa 100644
> --- a/gcc/expr.h
> +++ b/gcc/expr.h
> @@ -107,7 +107,15 @@ enum block_op_methods
>    BLOCK_OP_NO_LIBCALL_RET
>  };
>
> -typedef rtx (*by_pieces_constfn) (void *, HOST_WIDE_INT, scalar_int_mode);
> +typedef rtx (*by_pieces_constfn) (void *, void *, HOST_WIDE_INT,
> +                                 scalar_int_mode);
> +
> +/* The second pointer passed to by_pieces_constfn.  */
> +struct by_pieces_prev
> +{
> +  rtx data;
> +  scalar_int_mode mode;
> +};
>
>  extern rtx emit_block_move (rtx, rtx, rtx, enum block_op_methods);
>  extern rtx emit_block_move_hints (rtx, rtx, rtx, enum block_op_methods,
> diff --git a/gcc/target.def b/gcc/target.def
> index d7b94bd8e5d..7e2a2764ddc 100644
> --- a/gcc/target.def
> +++ b/gcc/target.def
> @@ -3630,6 +3630,15 @@ move would be greater than that of a library call.",
>          enum by_pieces_operation op, bool speed_p),
>   default_use_by_pieces_infrastructure_p)
>
> +DEFHOOK
> +(overlap_op_by_pieces_p,
> + "This target hook should return true if when the @code{by_pieces}\n\
> +infrastructure is used, an offset adjusted memory operation in the\n\
> +smallest integer mode for the last piece operation of a memory region\n\
> +can be generated to avoid doing more than one smaller operations.",
> + bool, (void),
> + hook_bool_void_false)
> +
>  DEFHOOK
>  (compare_by_pieces_branch_ratio,
>   "When expanding a block comparison in MODE, gcc can try to reduce the\n\
> diff --git a/gcc/testsuite/g++.dg/pr90773-1.h 
> b/gcc/testsuite/g++.dg/pr90773-1.h
> new file mode 100644
> index 00000000000..abdb78b078b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr90773-1.h
> @@ -0,0 +1,14 @@
> +class fixed_wide_int_storage {
> +public:
> +  long val[10];
> +  int len;
> +  fixed_wide_int_storage ()
> +    {
> +      len = sizeof (val) / sizeof (val[0]);
> +      for (int i = 0; i < len; i++)
> +       val[i] = i;
> +    }
> +};
> +
> +extern void foo (fixed_wide_int_storage);
> +extern int record_increment(void);
> diff --git a/gcc/testsuite/g++.dg/pr90773-1a.C 
> b/gcc/testsuite/g++.dg/pr90773-1a.C
> new file mode 100644
> index 00000000000..3ab8d929f74
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr90773-1a.C
> @@ -0,0 +1,13 @@
> +// { dg-do compile }
> +// { dg-options "-O2" }
> +// { dg-additional-options "-mno-avx -msse2 -mtune=skylake" { target { 
> i?86-*-* x86_64-*-* } } }
> +
> +#include "pr90773-1.h"
> +
> +int
> +record_increment(void)
> +{
> +  fixed_wide_int_storage x;
> +  foo (x);
> +  return 0;
> +}
> diff --git a/gcc/testsuite/g++.dg/pr90773-1b.C 
> b/gcc/testsuite/g++.dg/pr90773-1b.C
> new file mode 100644
> index 00000000000..9713b2dd612
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr90773-1b.C
> @@ -0,0 +1,5 @@
> +// { dg-do compile }
> +// { dg-options "-O2" }
> +// { dg-additional-options "-mno-avx512f -march=skylake" { target { i?86-*-* 
> x86_64-*-* } } }
> +
> +#include "pr90773-1a.C"
> diff --git a/gcc/testsuite/g++.dg/pr90773-1c.C 
> b/gcc/testsuite/g++.dg/pr90773-1c.C
> new file mode 100644
> index 00000000000..699357a88dc
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr90773-1c.C
> @@ -0,0 +1,5 @@
> +// { dg-do compile }
> +// { dg-options "-O2" }
> +// { dg-additional-options "-march=skylake-avx512" { target { i?86-*-* 
> x86_64-*-* } } }
> +
> +#include "pr90773-1a.C"
> diff --git a/gcc/testsuite/g++.dg/pr90773-1d.C 
> b/gcc/testsuite/g++.dg/pr90773-1d.C
> new file mode 100644
> index 00000000000..bf9d8543c1b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr90773-1d.C
> @@ -0,0 +1,19 @@
> +// { dg-do run }
> +// { dg-options "-O2" }
> +// { dg-additional-options "-march=native" { target { i?86-*-* x86_64-*-* } 
> } }
> +// { dg-additional-sources "pr90773-1a.C" }
> +
> +#include "pr90773-1.h"
> +
> +void
> +foo (fixed_wide_int_storage x)
> +{
> +  for (int i = 0; i < x.len; i++)
> +    if (x.val[i] != i)
> +      __builtin_abort ();
> +}
> +
> +int main ()
> +{
> +  return record_increment ();
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-1.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-1.c
> new file mode 100644
> index 00000000000..1d9f282dc0d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-1.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +
> +extern char *dst, *src;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memcpy (dst, src, 15);
> +}
> +
> +/* { dg-final { scan-assembler-times "movq\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movq\[\\t \]+7\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+4\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+8\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+11\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-10.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-10.c
> new file mode 100644
> index 00000000000..9ad725e4880
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-10.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (int c)
> +{
> +  __builtin_memset (dst, c, 5);
> +}
> +
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+.+, \\(%\[\^,\]+\\)" 1 } 
> } */
> +/* { dg-final { scan-assembler-times "movb\[\\t \]+.+, 4\\(%\[\^,\]+\\)" 1 } 
> } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-11.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-11.c
> new file mode 100644
> index 00000000000..1734c03a2eb
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-11.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (int c)
> +{
> +  __builtin_memset (dst, c, 6);
> +}
> +
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+.+, \\(%\[\^,\]+\\)" 1 } 
> } */
> +/* { dg-final { scan-assembler-times "movw\[\\t \]+.+, 4\\(%\[\^,\]+\\)" 1 } 
> } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-12.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-12.c
> new file mode 100644
> index 00000000000..e45840a5b8d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-12.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=skylake" } */
> +
> +void
> +foo (char *dst, char *src)
> +{
> +  __builtin_memcpy (dst, src, 255);
> +}
> +
> +/* { dg-final { scan-assembler-times "movdqu\[\\t 
> \]+\[0-9\]*\\(%\[\^,\]+\\)," 16 } } */
> +/* { dg-final { scan-assembler-not "mov\[bwlq\]" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-13.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-13.c
> new file mode 100644
> index 00000000000..4d5ae8d1086
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-13.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=skylake" } */
> +
> +void
> +foo (char *dst)
> +{
> +  __builtin_memset (dst, 0, 255);
> +}
> +
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> \[0-9\]*\\(%\[\^,\]+\\)" 16 } } */
> +/* { dg-final { scan-assembler-not "mov\[bwlq\]" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-14.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-14.c
> new file mode 100644
> index 00000000000..6364916ecac
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-14.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memset (dst, 1, 20);
> +}
> +
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> \\(%\[\^,\]+\\)" 1 } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+\\\$16843009, 
> 16\\(%\[\^,\]+\\)" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-2.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-2.c
> new file mode 100644
> index 00000000000..64495751b46
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-2.c
> @@ -0,0 +1,20 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +/* { dg-additional-options "-mno-avx -msse2" { target { ! ia32 } } } */
> +/* { dg-additional-options "-mno-sse" { target ia32 } } */
> +
> +extern char *dst, *src;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memcpy (dst, src, 19);
> +}
> +
> +/* { dg-final { scan-assembler-times "movdqu\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+15\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+4\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+8\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+12\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+15\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-3.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-3.c
> new file mode 100644
> index 00000000000..84747c94652
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-3.c
> @@ -0,0 +1,23 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +/* { dg-additional-options "-mno-avx -msse2" { target { ! ia32 } } } */
> +/* { dg-additional-options "-mno-sse" { target ia32 } } */
> +
> +extern char *dst, *src;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memcpy (dst, src, 31);
> +}
> +
> +/* { dg-final { scan-assembler-times "movdqu\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movdqu\[\\t \]+15\\(%\[\^,\]+\\)," 1 { 
> target { ! ia32 } } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+4\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+8\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+12\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+16\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+20\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+24\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+27\\(%\[\^,\]+\\)," 1 { 
> target ia32 } } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-4.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-4.c
> new file mode 100644
> index 00000000000..ec0bc0100ae
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-4.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memset (dst, 0, 31);
> +}
> +
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> \\(%\[\^,\]+\\)" 1 } } */
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> 15\\(%\[\^,\]+\\)" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-5.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-5.c
> new file mode 100644
> index 00000000000..49d03ef2403
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-5.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memset (dst, 0, 21);
> +}
> +
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> \\(%\[\^,\]+\\)" 1 } } */
> +/* { dg-final { scan-assembler-times "movq\[\\t \]+\\\$0+, 
> 13\\(%\[\^,\]+\\)" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-6.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-6.c
> new file mode 100644
> index 00000000000..46498f6f50c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-6.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=generic" } */
> +
> +void
> +foo (char *dst, char *src)
> +{
> +  __builtin_memcpy (dst, src, 255);
> +}
> +
> +/* { dg-final { scan-assembler-times "movdqu\[\\t 
> \]+\[0-9\]*\\(%\[\^,\]+\\)," 16 } } */
> +/* { dg-final { scan-assembler-not "mov\[bwlq\]" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-7.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-7.c
> new file mode 100644
> index 00000000000..4d5ae8d1086
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-7.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2 -mno-avx -msse2 -mtune=skylake" } */
> +
> +void
> +foo (char *dst)
> +{
> +  __builtin_memset (dst, 0, 255);
> +}
> +
> +/* { dg-final { scan-assembler-times "movups\[\\t \]+%xmm\[0-9\]+, 
> \[0-9\]*\\(%\[\^,\]+\\)" 16 } } */
> +/* { dg-final { scan-assembler-not "mov\[bwlq\]" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-8.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-8.c
> new file mode 100644
> index 00000000000..0d47845d560
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-8.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memset (dst, 0, 5);
> +}
> +
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+.+, \\(%\[\^,\]+\\)" 1 } 
> } */
> +/* { dg-final { scan-assembler-times "movb\[\\t \]+.+, 4\\(%\[\^,\]+\\)" 1 } 
> } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr90773-9.c 
> b/gcc/testsuite/gcc.target/i386/pr90773-9.c
> new file mode 100644
> index 00000000000..ab5ea451f30
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr90773-9.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mtune=generic" } */
> +
> +extern char *dst;
> +
> +void
> +foo (void)
> +{
> +  __builtin_memset (dst, 0, 6);
> +}
> +
> +/* { dg-final { scan-assembler-times "movl\[\\t \]+.+, \\(%\[\^,\]+\\)" 1 } 
> } */
> +/* { dg-final { scan-assembler-times "movw\[\\t \]+.+, 4\\(%\[\^,\]+\\)" 1 } 
> } */
> --
> 2.30.2
>

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