On Mon, Jul 19, 2021 at 7:41 AM Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> "H.J. Lu via Gcc-patches" <gcc-patches@gcc.gnu.org> writes:
> > On Fri, Jul 16, 2021 at 7:15 AM H.J. Lu <hjl.to...@gmail.com> wrote:
> >>
> >> On Fri, Jul 16, 2021 at 6:24 AM Richard Sandiford
> >> <richard.sandif...@arm.com> wrote:
> >> >
> >> > "H.J. Lu via Gcc-patches" <gcc-patches@gcc.gnu.org> writes:
> >> > > On Fri, Jul 16, 2021 at 4:38 AM Richard Sandiford
> >> > > <richard.sandif...@arm.com> wrote:
> >> > >>
> >> > >> "H.J. Lu via Gcc-patches" <gcc-patches@gcc.gnu.org> writes:
> >> > >> > 1. Rewrite builtin_memset_read_str and builtin_memset_gen_str with
> >> > >> > vec_duplicate_optab to duplicate QI value to TI/OI/XI value.
> >> > >> > 2. Add TARGET_GEN_MEMSET_SCRATCH_RTX to allow the backend to use a
> >> > >> > hard
> >> > >> > scratch register to avoid stack realignment when expanding memset.
> >> > >> >
> >> > >> > PR middle-end/90773
> >> > >> > * builtins.c (gen_memset_value_from_prev): New function.
> >> > >> > (gen_memset_broadcast): Likewise.
> >> > >> > (builtin_memset_read_str): Use gen_memset_value_from_prev
> >> > >> > and gen_memset_broadcast.
> >> > >> > (builtin_memset_gen_str): Likewise.
> >> > >> > * target.def (gen_memset_scratch_rtx): New hook.
> >> > >> > * doc/tm.texi.in: Add TARGET_GEN_MEMSET_SCRATCH_RTX.
> >> > >> > * doc/tm.texi: Regenerated.
> >> > >> > ---
> >> > >> > gcc/builtins.c | 123
> >> > >> > +++++++++++++++++++++++++++++++++++++--------
> >> > >> > gcc/doc/tm.texi | 5 ++
> >> > >> > gcc/doc/tm.texi.in | 2 +
> >> > >> > gcc/target.def | 7 +++
> >> > >> > 4 files changed, 116 insertions(+), 21 deletions(-)
> >> > >> >
> >> > >> > diff --git a/gcc/builtins.c b/gcc/builtins.c
> >> > >> > index 39ab139b7e1..c1758ae2efc 100644
> >> > >> > --- a/gcc/builtins.c
> >> > >> > +++ b/gcc/builtins.c
> >> > >> > @@ -6686,26 +6686,111 @@ expand_builtin_strncpy (tree exp, rtx
> >> > >> > target)
> >> > >> > return NULL_RTX;
> >> > >> > }
> >> > >> >
> >> > >> > -/* Callback routine for store_by_pieces. Read GET_MODE_BITSIZE
> >> > >> > (MODE)
> >> > >> > - bytes from constant string DATA + OFFSET and return it as target
> >> > >> > - constant. If PREV isn't nullptr, it has the RTL info from the
> >> > >> > +/* Return the RTL of a register in MODE generated from PREV in the
> >> > >> > previous iteration. */
> >> > >> >
> >> > >> > -rtx
> >> > >> > -builtin_memset_read_str (void *data, void *prevp,
> >> > >> > - HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> >> > >> > - scalar_int_mode mode)
> >> > >> > +static rtx
> >> > >> > +gen_memset_value_from_prev (void *prevp, scalar_int_mode mode)
> >> > >> > {
> >> > >> > + rtx target = nullptr;
> >> > >> > 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;
> >> > >> > +
> >> > >> > + rtx prev_rtx = prev->data;
> >> > >> > + machine_mode prev_mode = prev->mode;
> >> > >> > + unsigned int word_size = GET_MODE_SIZE (word_mode);
> >> > >> > + if (word_size < GET_MODE_SIZE (prev->mode)
> >> > >> > + && word_size > GET_MODE_SIZE (mode))
> >> > >> > + {
> >> > >> > + /* First generate subreg of word mode if the previous mode
> >> > >> > is
> >> > >> > + wider than word mode and word mode is wider than MODE.
> >> > >> > */
> >> > >> > + prev_rtx = simplify_gen_subreg (word_mode, prev_rtx,
> >> > >> > + prev_mode, 0);
> >> > >> > + prev_mode = word_mode;
> >> > >> > + }
> >> > >> > + if (prev_rtx != nullptr)
> >> > >> > + target = simplify_gen_subreg (mode, prev_rtx, prev_mode, 0);
> >> > >> > }
> >> > >> > + return target;
> >> > >> > +}
> >> > >> > +
> >> > >> > +/* Return the RTL of a register in MODE broadcasted from DATA. */
> >> > >> > +
> >> > >> > +static rtx
> >> > >> > +gen_memset_broadcast (rtx data, scalar_int_mode mode)
> >> > >> > +{
> >> > >> > + /* Skip if regno_reg_rtx isn't initialized. */
> >> > >> > + if (!regno_reg_rtx)
> >> > >> > + return nullptr;
> >> > >> > +
> >> > >> > + rtx target = nullptr;
> >> > >> > +
> >> > >> > + unsigned int nunits = GET_MODE_SIZE (mode) / GET_MODE_SIZE
> >> > >> > (QImode);
> >> > >> > + machine_mode vector_mode;
> >> > >> > + if (!mode_for_vector (QImode, nunits).exists (&vector_mode))
> >> > >> > + gcc_unreachable ();
> >> > >>
> >> > >> Sorry, I realise it's a bit late to be raising this objection now,
> >> > >> but I don't think it's a good idea to use scalar integer modes as
> >> > >> a proxy for vector modes. In principle there's no reason why a
> >> > >> target has to define an integer mode for every vector mode.
> >> > >
> >> > > A target always defines the largest integer mode.
> >> >
> >> > Right. But a target shouldn't *need* to define an integer mode
> >> > for every vector mode.
> >> >
> >> > >> If we want the mode to be a vector then I think the by-pieces
> >> > >> infrastructure should be extended to support vectors directly,
> >> > >> rather than assuming that each piece can be represented as
> >> > >> a scalar_int_mode.
> >> > >>
> >> > >
> >> > > The current by-pieces infrastructure operates on scalar_int_mode.
> >> > > Only for memset, there is
> >> > >
> >> > > /* 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. If PREV isn't
> >> > > nullptr, it has the RTL info from the previous iteration. */
> >> > >
> >> > > static rtx
> >> > > builtin_memset_gen_str (void *data, void *prevp,
> >> > > HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> >> > > scalar_int_mode mode)
> >> > >
> >> > > It is a broadcast. If a target can broadcast a byte to a wider
> >> > > integer,
> >> > > can you suggest a way to use it in the current by-pieces
> >> > > infrastructure?
> >> >
> >> > I meant that we should extend the by-pieces infrastructure so that
> >> > it no longer requires scalar_int_mode, rather than work within the
> >> > current limits.
> >> >
> >> > IMO the fact that we're (legitimately) going through vec_duplicate_optab
> >>
> >> If vec_duplicate_optab is the only blocking issue, can we add an integer
> >> broadcast optab? I want to avoid a major surgery just because we
> >> don't support integer broadcast from byte.
> >>
> >> > shows that we really are dealing with vectors here, not integers.
> >> >
> >>
> >> Are you suggesting we should add the optional vector mode
> >> support to by-pieces for memset?
> >>
> >
> > Like this?
> >
> > 1. Replace scalar_int_mode with machine_mode in the by-pieces
> > infrastructure to allow non-integer mode.
>
> I guess it might be better to use fixed_size_mode instead of
> machine_mode.
Fixed.
> > 2. Rename widest_int_mode_for_size to widest_int_or_QI_vector_mode_for_size
> > to return QI vector mode for memset.
> > 3. Add op_by_pieces_d::smallest_mode_for_size to return the smallest
> > integer or QI vector mode.
> >
> > Thanks.
> >
> > --
> > H.J.
> >
> > From 171f0a919300a8aac58dfe5fc9904eaa8fe0a05b Mon Sep 17 00:00:00 2001
> > From: "H.J. Lu" <hjl.to...@gmail.com>
> > Date: Sun, 6 Mar 2016 06:38:21 -0800
> > Subject: [PATCH] Add QI vector mode support to by-pieces for memset
> >
> > 1. Replace scalar_int_mode with machine_mode in the by-pieces
> > infrastructure to allow non-integer mode.
> > 2. Rename widest_int_mode_for_size to widest_int_or_QI_vector_mode_for_size
> > to return QI vector mode for memset.
> > 3. Add op_by_pieces_d::smallest_mode_for_size to return the smallest
> > integer or QI vector mode.
> >
> > gcc/
> >
> > PR middle-end/90773
> > * builtins.c (builtin_memcpy_read_str): Change the mode argument
> > from scalar_int_mode to machine_mode.
> > (builtin_strncpy_read_str): Likewise.
> > (gen_memset_value_from_prev): New function.
> > (gen_memset_broadcast): Likewise.
> > (builtin_memset_read_str): Change the mode argument from
> > scalar_int_mode to machine_mode. Use gen_memset_value_from_prev
> > and gen_memset_broadcast.
> > (builtin_memset_gen_str): Likewise.
> > (try_store_by_multiple_pieces): Use by_pieces_constfn to declare
> > constfun.
> > * builtins.h (builtin_strncpy_read_str): Updated.
> > (builtin_memset_read_str): Likewise.
> > * expr.c (widest_int_mode_for_size): Renamed to ...
> > (widest_int_or_QI_vector_mode_for_size): Add a bool argument to
> > indicate if QI vector mode can be used.
> > (by_pieces_ninsns): Call widest_int_or_QI_vector_mode_for_size
> > instead of widest_int_mode_for_size.
> > (pieces_addr::adjust): Change the mode argument from
> > scalar_int_mode to machine_mode.
> > (op_by_pieces_d): Add a bool member, m_qi_vector_mode, to
> > indicate that QI vector mode can be used.
> > (op_by_pieces_d::op_by_pieces_d): Add a bool argument to initialize
> > m_qi_vector_mode. Call widest_int_or_QI_vector_mode_for_size
> > instead of widest_int_mode_for_size.
> > (op_by_pieces_d::get_usable_mode): Change the mode argument from
> > scalar_int_mode to machine_mode. Call
> > widest_int_or_QI_vector_mode_for_size instead of
> > widest_int_mode_for_size.
> > (op_by_pieces_d::smallest_mode_for_size): New member function
> > to return the smallest integer or QI vector mode.
> > (op_by_pieces_d::run): Call widest_int_or_QI_vector_mode_for_size
> > instead of widest_int_mode_for_size. Call smallest_mode_for_size
> > instead of smallest_int_mode_for_size.
> > (store_by_pieces_d::store_by_pieces_d): Add a bool argument to
> > indicate that QI vector mode can be used and pass it to
> > op_by_pieces_d::op_by_pieces_d.
> > (can_store_by_pieces): Call widest_int_or_QI_vector_mode_for_size
> > instead of widest_int_mode_for_size.
> > (store_by_pieces::store_by_pieces): Pass memsetp to
> > store_by_pieces_d::store_by_pieces_d.
> > (clear_by_pieces_1): Change scalar_int_mode to machine_mode.
> > (string_cst_read_str): Change the mode argument from
> > scalar_int_mode to machine_mode.
> > * expr.h (by_pieces_constfn): Change scalar_int_mode to
> > machine_mode.
> > (by_pieces_prev): Likewise.
> > * target.def (gen_memset_scratch_rtx): New hook.
> > * doc/tm.texi.in: Add TARGET_GEN_MEMSET_SCRATCH_RTX.
> > * doc/tm.texi: Regenerated.
> >
> > gcc/testsuite/
> >
> > * gcc.target/i386/pr100865-3.c: Expect vmovdqu8 instead of
> > vmovdqu.
> > * gcc.target/i386/pr100865-4b.c: Likewise.
> > ---
> > gcc/builtins.c | 138 ++++++++++++++-----
> > gcc/builtins.h | 4 +-
> > gcc/doc/tm.texi | 5 +
> > gcc/doc/tm.texi.in | 2 +
> > gcc/expr.c | 145 ++++++++++++++------
> > gcc/expr.h | 4 +-
> > gcc/target.def | 7 +
> > gcc/testsuite/gcc.target/i386/pr100865-3.c | 2 +-
> > gcc/testsuite/gcc.target/i386/pr100865-4b.c | 2 +-
> > 9 files changed, 229 insertions(+), 80 deletions(-)
> >
> > diff --git a/gcc/builtins.c b/gcc/builtins.c
> > index 39ab139b7e1..876378b467c 100644
> > --- a/gcc/builtins.c
> > +++ b/gcc/builtins.c
> > @@ -3890,13 +3890,14 @@ expand_builtin_strnlen (tree exp, rtx target,
> > machine_mode target_mode)
> >
> > static rtx
> > builtin_memcpy_read_str (void *data, void *, HOST_WIDE_INT offset,
> > - scalar_int_mode mode)
> > + machine_mode mode)
> > {
> > /* The REPresentation pointed to by DATA need not be a nul-terminated
> > string but the caller guarantees it's large enough for MODE. */
> > const char *rep = (const char *) data;
> >
> > - return c_readstr (rep + offset, mode, /*nul_terminated=*/false);
> > + return c_readstr (rep + offset, as_a <scalar_int_mode> (mode),
> > + /*nul_terminated=*/false);
> > }
> >
> > /* LEN specify length of the block of memcpy/memset operation.
> > @@ -6478,14 +6479,14 @@ expand_builtin_stpncpy (tree exp, rtx)
> >
> > rtx
> > builtin_strncpy_read_str (void *data, void *, HOST_WIDE_INT offset,
> > - scalar_int_mode mode)
> > + machine_mode mode)
> > {
> > const char *str = (const char *) data;
> >
> > if ((unsigned HOST_WIDE_INT) offset > strlen (str))
> > return const0_rtx;
> >
> > - return c_readstr (str + offset, mode);
> > + return c_readstr (str + offset, as_a <scalar_int_mode> (mode));
> > }
> > /* Helper to check the sizes of sequences and the destination of calls
>
> I think both of these as_a<scalar_int_mode>s should have a comment
> explaining that we don't (yet?) consider using vector modes for this
> operation.
Fixed.
> > @@ -6686,30 +6687,109 @@ expand_builtin_strncpy (tree exp, rtx target)
> > return NULL_RTX;
> > }
> >
> > -/* Callback routine for store_by_pieces. Read GET_MODE_BITSIZE (MODE)
> > - bytes from constant string DATA + OFFSET and return it as target
> > - constant. If PREV isn't nullptr, it has the RTL info from the
> > +/* Return the RTL of a register in MODE generated from PREV in the
> > previous iteration. */
> >
> > -rtx
> > -builtin_memset_read_str (void *data, void *prevp,
> > - HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> > - scalar_int_mode mode)
> > +static rtx
> > +gen_memset_value_from_prev (void *prevp, machine_mode mode)
> > {
> > + rtx target = nullptr;
> > by_pieces_prev *prev = (by_pieces_prev *) prevp;
>
> I think it'd be better to pass the proper type instead, since this
> function isn't directly implementing a callback interface.
Fixed.
> > if (prev != nullptr && prev->data != nullptr)
> > {
> > /* Use the previous data in the same mode. */
> > if (prev->mode == mode)
> > return prev->data;
> > +
> > + rtx prev_rtx = prev->data;
> > + machine_mode prev_mode = prev->mode;
> > + unsigned int word_size = GET_MODE_SIZE (word_mode);
> > + if (word_size < GET_MODE_SIZE (prev->mode).to_constant ()
> > + && word_size > GET_MODE_SIZE (mode).to_constant ())
>
> Using fixed_size_mode would also avoid the to_constants here.
Fixed.
> UNITS_PER_WORD is more direct/canonical than GET_MODE_SIZE (word_mode).
Fixed.
> > + {
> > + /* First generate subreg of word mode if the previous mode is
> > + wider than word mode and word mode is wider than MODE. */
> > + prev_rtx = simplify_gen_subreg (word_mode, prev_rtx,
> > + prev_mode, 0);
> > + prev_mode = word_mode;
> > + }
> > + if (prev_rtx != nullptr)
> > + target = simplify_gen_subreg (mode, prev_rtx, prev_mode, 0);
>
> This should be lowpart_subreg, since 0 isn't the right offset for
> big-endian targets. Using lowpart_subreg should also avoid the need
> for the word_size “if” above: lowpart_subreg can handle lowpart subword
> subregs of multiword values.
I tried it. It didn't work since it caused the LRA failure. I replaced
simplify_gen_subreg with lowpart_subreg instead.
> > + }
> > + return target;
> > +}
> > +
> > +/* Return the RTL of a register in MODE broadcasted from DATA. */
> > +
> > +static rtx
> > +gen_memset_broadcast (rtx data, machine_mode mode)
> > +{
> > + /* Skip if regno_reg_rtx isn't initialized or not vector mode. */
>
> Why's the regno_reg_rtx condition needed?
Removed.
> > + if (!regno_reg_rtx || !VECTOR_MODE_P (mode))
> > + return nullptr;
> > +
> > + gcc_assert (GET_MODE_INNER (mode) == QImode);
> > +
> > + enum insn_code icode = optab_handler (vec_duplicate_optab, mode);
> > +
> > + gcc_assert (icode != CODE_FOR_nothing);
>
> Might be worth a comment here saying that having vec_duplicate_optab is
> a precondition for picking a vector mode.
I added a comment.
> > +
> > + rtx target = targetm.gen_memset_scratch_rtx (mode);
> > + if (CONST_INT_P (data))
> > + {
> > + /* Use the move expander with CONST_VECTOR. */
> > + rtx const_vec = gen_const_vec_duplicate (mode, data);
> > + emit_move_insn (target, const_vec);
> > + }
> > + else
> > + {
> > +
>
> Nit: excess blank line.
Fixed.
> > + class expand_operand ops[2];
> > + create_output_operand (&ops[0], target, mode);
> > + create_input_operand (&ops[1], data, QImode);
> > + expand_insn (icode, 2, ops);
> > + if (!rtx_equal_p (target, ops[0].value))
> > + emit_move_insn (target, ops[0].value);
> > }
> >
> > + return target;
> > +}
> > +
> > +/* Callback routine for store_by_pieces. Read GET_MODE_BITSIZE (MODE)
> > + bytes from constant string DATA + OFFSET and return it as target
> > + constant. If PREV isn't nullptr, it has the RTL info from the
> > + previous iteration. */
> > +
> > +rtx
> > +builtin_memset_read_str (void *data, void *prev,
> > + HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> > + machine_mode mode)
> > +{
> > + rtx target;
> > const char *c = (const char *) data;
> > - char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
> > + char *p;
> > + unsigned int size = GET_MODE_SIZE (mode).to_constant ();
> > +
> > + /* Don't use the previous value if size is 1. */
>
> Why not though? The existing code does, and that seems like the right
> thing to do when operating on integers.
>
> I can see the check would be a good thing to do if MODE isn't a vector
> mode and the previous mode was. Is that the case you're worried about?
> If so, that check could go in gen_memset_value_from_prev instead.
We are storing one byte. Doing it directly is faster.
> > + if (size != 1)
> > + {
> > + target = gen_memset_value_from_prev (prev, mode);
> > + if (target != nullptr)
> > + return target;
> > +
> > + p = XALLOCAVEC (char, GET_MODE_SIZE (QImode));
> > + memset (p, *c, GET_MODE_SIZE (QImode));
> > + rtx src = c_readstr (p, QImode);
>
> This seems unnecessarily complicated. Couldn't it just be
>
> gen_int_mode (QImode, *c);
>
> instead? There are no endianness concerns for single QI values.
Fixed.
> > + target = gen_memset_broadcast (src, mode);
> > + if (target != nullptr)
> > + return target;
> > + }
> > +
> > + p = XALLOCAVEC (char, size);
> >
> > - memset (p, *c, GET_MODE_SIZE (mode));
> > + memset (p, *c, size);
> >
> > - return c_readstr (p, mode);
> > + return c_readstr (p, as_a <scalar_int_mode> (mode));
> > }
> >
> > /* Callback routine for store_by_pieces. Return the RTL of a register
> > @@ -6719,33 +6799,29 @@ builtin_memset_read_str (void *data, void *prevp,
> > nullptr, it has the RTL info from the previous iteration. */
> >
> > static rtx
> > -builtin_memset_gen_str (void *data, void *prevp,
> > +builtin_memset_gen_str (void *data, void *prev,
> > HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> > - scalar_int_mode mode)
> > + machine_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;
> > -
> > - target = simplify_gen_subreg (mode, prev->data, prev->mode, 0);
> > - if (target != nullptr)
> > - return target;
> > - }
> > -
> > - size = GET_MODE_SIZE (mode);
> > + size = GET_MODE_SIZE (mode).to_constant ();
> > if (size == 1)
> > return (rtx) data;
> >
> > + target = gen_memset_value_from_prev (prev, mode);
> > + if (target != nullptr)
> > + return target;
> > +
> > + target = gen_memset_broadcast ((rtx) data, mode);
> > + if (target != nullptr)
> > + return target;
> > +
> > p = XALLOCAVEC (char, size);
> > memset (p, 1, size);
> > - coeff = c_readstr (p, mode);
> > + coeff = c_readstr (p, as_a <scalar_int_mode> (mode));
> >
> > target = convert_to_mode (mode, (rtx) data, 1);
> > target = expand_mult (mode, target, coeff, NULL_RTX, 1);
> > @@ -6849,7 +6925,7 @@ try_store_by_multiple_pieces (rtx to, rtx len,
> > unsigned int ctz_len,
> > &valc, align, true))
> > return false;
> >
> > - rtx (*constfun) (void *, void *, HOST_WIDE_INT, scalar_int_mode);
> > + by_pieces_constfn constfun;
> > void *constfundata;
> > if (val)
> > {
> > diff --git a/gcc/builtins.h b/gcc/builtins.h
> > index a64ece3f1cd..31d07621750 100644
> > --- a/gcc/builtins.h
> > +++ b/gcc/builtins.h
> > @@ -111,9 +111,9 @@ 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 *, void *, HOST_WIDE_INT,
> > - scalar_int_mode);
> > + machine_mode);
> > extern rtx builtin_memset_read_str (void *, void *, HOST_WIDE_INT,
> > - scalar_int_mode);
> > + machine_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/doc/tm.texi b/gcc/doc/tm.texi
> > index 3ad39443eba..c1995270720 100644
> > --- a/gcc/doc/tm.texi
> > +++ b/gcc/doc/tm.texi
> > @@ -12123,6 +12123,11 @@ This function prepares to emit a conditional
> > comparison within a sequence
> > @var{bit_code} is @code{AND} or @code{IOR}, which is the op on the
> > compares.
> > @end deftypefn
> >
> > +@deftypefn {Target Hook} rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode
> > @var{mode})
> > +This hook should return an rtx for scratch register in @var{mode} to
> > +be used by memset broadcast. The default is @code{gen_reg_rtx}.
>
> This should give a hint why the default might not be appropriate.
Updated.
> > +@end deftypefn
> > +
> > @deftypefn {Target Hook} unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned
> > @var{nunroll}, class loop *@var{loop})
> > This target hook returns a new value for the number of times @var{loop}
> > should be unrolled. The parameter @var{nunroll} is the number of times
> > diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> > index f881cdabe9e..a6bbf4f2667 100644
> > --- a/gcc/doc/tm.texi.in
> > +++ b/gcc/doc/tm.texi.in
> > @@ -7958,6 +7958,8 @@ lists.
> >
> > @hook TARGET_GEN_CCMP_NEXT
> >
> > +@hook TARGET_GEN_MEMSET_SCRATCH_RTX
> > +
> > @hook TARGET_LOOP_UNROLL_ADJUST
> >
> > @defmac POWI_MAX_MULTS
> > diff --git a/gcc/expr.c b/gcc/expr.c
> > index 6a4368113c4..92dbf47194e 100644
> > --- a/gcc/expr.c
> > +++ b/gcc/expr.c
> > @@ -769,15 +769,36 @@ alignment_for_piecewise_move (unsigned int
> > max_pieces, unsigned int align)
> > return align;
> > }
> >
> > -/* Return the widest integer mode that is narrower than SIZE bytes. */
> > +/* Return the widest integer or QI vector mode that is narrower than
> > + SIZE bytes. */
> >
> > -static scalar_int_mode
> > -widest_int_mode_for_size (unsigned int size)
> > +static machine_mode
> > +widest_int_or_QI_vector_mode_for_size (unsigned int size,
> > + bool qi_vector)
> > {
> > - scalar_int_mode result = NARROWEST_INT_MODE;
> > + machine_mode result = NARROWEST_INT_MODE;
> >
> > gcc_checking_assert (size > 1);
> >
> > + /* Use QI vector only if size is wider than a WORD. */
> > + if (qi_vector && size > GET_MODE_SIZE (word_mode))
> > + {
> > + machine_mode mode;
> > + FOR_EACH_MODE_IN_CLASS (mode, MODE_VECTOR_INT)
> > + if (GET_MODE_INNER (mode) == QImode
> > + && GET_MODE_SIZE (mode).is_constant ())
> > + {
> > + if (GET_MODE_SIZE (mode).to_constant () >= size)
> > + break;
> > + if (optab_handler (vec_duplicate_optab, mode)
> > + != CODE_FOR_nothing)
> > + result = mode;
> > + }
> > +
> > + if (result != NARROWEST_INT_MODE)
> > + return result;
> > + }
> > +
> > opt_scalar_int_mode tmode;
> > FOR_EACH_MODE_IN_CLASS (tmode, MODE_INT)
> > if (GET_MODE_SIZE (tmode.require ()) < size)
> > @@ -815,16 +836,18 @@ 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;
> > + machine_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);
> > + mode = widest_int_or_QI_vector_mode_for_size (max_size,
> > + op == SET_BY_PIECES);
> > if (optab_handler (mov_optab, mode) != CODE_FOR_nothing)
> > {
> > - unsigned HOST_WIDE_INT up = ROUND_UP (l, GET_MODE_SIZE (mode));
> > + unsigned HOST_WIDE_INT up = ROUND_UP (l,
> > + GET_MODE_SIZE
> > (mode).to_constant ());
> > if (up > l)
> > l = up;
> > align = GET_MODE_ALIGNMENT (mode);
> > @@ -835,10 +858,11 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l, unsigned
> > int align,
> >
> > while (max_size > 1 && l > 0)
> > {
> > - mode = widest_int_mode_for_size (max_size);
> > + mode = widest_int_or_QI_vector_mode_for_size (max_size,
> > + op == SET_BY_PIECES);
> > enum insn_code icode;
> >
> > - unsigned int modesize = GET_MODE_SIZE (mode);
> > + unsigned int modesize = GET_MODE_SIZE (mode).to_constant ();
> >
> > icode = optab_handler (mov_optab, mode);
> > if (icode != CODE_FOR_nothing && align >= GET_MODE_ALIGNMENT (mode))
> > @@ -903,8 +927,7 @@ class pieces_addr
> > void *m_cfndata;
> > public:
> > pieces_addr (rtx, bool, by_pieces_constfn, void *);
> > - rtx adjust (scalar_int_mode, HOST_WIDE_INT,
> > - by_pieces_prev * = nullptr);
> > + rtx adjust (machine_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);
> > @@ -1006,7 +1029,7 @@ 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 (machine_mode mode, HOST_WIDE_INT offset,
> > by_pieces_prev *prev)
> > {
> > if (m_constfn)
> > @@ -1060,7 +1083,8 @@ 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);
> > + machine_mode get_usable_mode (machine_mode, unsigned int);
> > + machine_mode smallest_mode_for_size (unsigned int);
> >
> > protected:
> > pieces_addr m_to, m_from;
> > @@ -1073,6 +1097,8 @@ class op_by_pieces_d
> > bool m_push;
> > /* True if targetm.overlap_op_by_pieces_p () returns true. */
> > bool m_overlap_op_by_pieces;
> > + /* True if QI vector mode can be used. */
> > + bool m_qi_vector_mode;
> >
> > /* Virtual functions, overriden by derived classes for the specific
> > operation. */
> > @@ -1084,7 +1110,8 @@ class op_by_pieces_d
> >
> > public:
> > op_by_pieces_d (rtx, bool, rtx, bool, by_pieces_constfn, void *,
> > - unsigned HOST_WIDE_INT, unsigned int, bool);
> > + unsigned HOST_WIDE_INT, unsigned int, bool,
> > + bool = false);
> > void run ();
> > };
> >
> > @@ -1099,11 +1126,12 @@ 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, bool push)
> > + unsigned int align, bool push,
> > + bool qi_vector_mode)
> > : 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_push (push)
> > + m_push (push), m_qi_vector_mode (qi_vector_mode)
> > {
> > int toi = m_to.get_addr_inc ();
> > int fromi = m_from.get_addr_inc ();
> > @@ -1124,7 +1152,9 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool to_load,
> > if (by_pieces_ninsns (len, align, m_max_size, MOVE_BY_PIECES) > 2)
> > {
> > /* Find the mode of the largest comparison. */
> > - scalar_int_mode mode = widest_int_mode_for_size (m_max_size);
> > + machine_mode mode
> > + = widest_int_or_QI_vector_mode_for_size (m_max_size,
> > + m_qi_vector_mode);
> >
> > m_from.decide_autoinc (mode, m_reverse, len);
> > m_to.decide_autoinc (mode, m_reverse, len);
> > @@ -1139,22 +1169,42 @@ op_by_pieces_d::op_by_pieces_d (rtx to, bool
> > to_load,
> > /* 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)
> > +machine_mode
> > +op_by_pieces_d::get_usable_mode (machine_mode mode, unsigned int len)
> > {
> > unsigned int size;
> > do
> > {
> > - size = GET_MODE_SIZE (mode);
> > + size = GET_MODE_SIZE (mode).to_constant ();
> > 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);
> > + /* NB: widest_int_or_QI_vector_mode_for_size checks SIZE > 1. */
> > + mode = widest_int_or_QI_vector_mode_for_size (size,
> > + m_qi_vector_mode);
> > }
> > while (1);
> > return mode;
> > }
> >
> > +/* Return the smallest integer or QI vector mode that is not narrower
> > + than SIZE bits. */
> > +
> > +machine_mode
> > +op_by_pieces_d::smallest_mode_for_size (unsigned int size)
> > +{
> > + /* Use QI vector only for > size of WORD. */
> > + if (m_qi_vector_mode && size > GET_MODE_PRECISION (word_mode))
> > + {
> > + machine_mode mode;
> > + FOR_EACH_MODE_IN_CLASS (mode, MODE_VECTOR_INT)
> > + if (GET_MODE_INNER (mode) == QImode
> > + && known_ge (GET_MODE_PRECISION (mode), size))
> > + return mode;
>
> Shouldn't this also test for vec_duplicate_optab? I guess you're
> hoping that the previous register will be reused via a lowpart,
> but since that's up to the callbacks, I think we should be
> conservative here.
Fixed. I will submit the v2 patch.
Thanks.
> Alternatively, we could bypass the callbacks when this code is used.
>
> Thanks,
> Richard
>
> > + }
> > +
> > + return smallest_int_mode_for_size (size);
> > +}
> > +
> > /* This function contains the main loop used for expanding a block
> > operation. First move what we can in the largest integer mode,
> > then go to successively smaller modes. For every access, call
> > @@ -1166,8 +1216,10 @@ op_by_pieces_d::run ()
> > 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);
> > + /* NB: widest_int_or_QI_vector_mode_for_size checks M_MAX_SIZE > 1. */
> > + machine_mode mode
> > + = widest_int_or_QI_vector_mode_for_size (m_max_size,
> > + m_qi_vector_mode);
> > mode = get_usable_mode (mode, m_len);
> >
> > by_pieces_prev to_prev = { nullptr, mode };
> > @@ -1175,7 +1227,7 @@ op_by_pieces_d::run ()
> >
> > do
> > {
> > - unsigned int size = GET_MODE_SIZE (mode);
> > + unsigned int size = GET_MODE_SIZE (mode).to_constant ();
> > rtx to1 = NULL_RTX, from1;
> >
> > while (m_len >= size)
> > @@ -1214,9 +1266,10 @@ op_by_pieces_d::run ()
> > /* 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;
> > + mode = smallest_mode_for_size (m_len * BITS_PER_UNIT);
> > + unsigned int mode_size = GET_MODE_SIZE (mode).to_constant ();
> > + mode = get_usable_mode (mode, mode_size);
> > + int gap = mode_size - m_len;
> > if (gap > 0)
> > {
> > /* If size of MODE > M_LEN, generate the last operation
> > @@ -1231,8 +1284,9 @@ op_by_pieces_d::run ()
> > }
> > else
> > {
> > - /* NB: widest_int_mode_for_size checks SIZE > 1. */
> > - mode = widest_int_mode_for_size (size);
> > + /* NB: widest_int_or_QI_vector_mode_for_size checks SIZE > 1. */
> > + mode = widest_int_or_QI_vector_mode_for_size (size,
> > + m_qi_vector_mode);
> > mode = get_usable_mode (mode, m_len);
> > }
> > }
> > @@ -1355,9 +1409,10 @@ 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)
> > + unsigned HOST_WIDE_INT len, unsigned int align,
> > + bool qi_vector_mode = false)
> > : op_by_pieces_d (to, false, NULL_RTX, true, cfn, cfn_data, len,
> > - align, false)
> > + align, false, qi_vector_mode)
> > {
> > }
> > rtx finish_retmode (memop_ret);
> > @@ -1446,13 +1501,14 @@ can_store_by_pieces (unsigned HOST_WIDE_INT len,
> > max_size = STORE_MAX_PIECES + 1;
> > while (max_size > 1 && l > 0)
> > {
> > - scalar_int_mode mode = widest_int_mode_for_size (max_size);
> > + machine_mode mode
> > + = widest_int_or_QI_vector_mode_for_size (max_size, memsetp);
> >
> > icode = optab_handler (mov_optab, mode);
> > if (icode != CODE_FOR_nothing
> > && align >= GET_MODE_ALIGNMENT (mode))
> > {
> > - unsigned int size = GET_MODE_SIZE (mode);
> > + unsigned int size = GET_MODE_SIZE (mode).to_constant ();
> >
> > while (l >= size)
> > {
> > @@ -1470,7 +1526,7 @@ can_store_by_pieces (unsigned HOST_WIDE_INT len,
> > }
> > }
> >
> > - max_size = GET_MODE_SIZE (mode);
> > + max_size = GET_MODE_SIZE (mode).to_constant ();
> > }
> >
> > /* The code above should have handled everything. */
> > @@ -1504,7 +1560,8 @@ store_by_pieces (rtx to, unsigned HOST_WIDE_INT len,
> > memsetp ? SET_BY_PIECES : STORE_BY_PIECES,
> > optimize_insn_for_speed_p ()));
> >
> > - store_by_pieces_d data (to, constfun, constfundata, len, align);
> > + store_by_pieces_d data (to, constfun, constfundata, len, align,
> > + memsetp);
> > data.run ();
> >
> > if (retmode != RETURN_BEGIN)
> > @@ -1517,7 +1574,7 @@ store_by_pieces (rtx to, unsigned HOST_WIDE_INT len,
> > Return const0_rtx unconditionally. */
> >
> > static rtx
> > -clear_by_pieces_1 (void *, void *, HOST_WIDE_INT, scalar_int_mode)
> > +clear_by_pieces_1 (void *, void *, HOST_WIDE_INT, machine_mode)
> > {
> > return const0_rtx;
> > }
> > @@ -5754,7 +5811,7 @@ emit_storent_insn (rtx to, rtx from)
> >
> > static rtx
> > string_cst_read_str (void *data, void *, HOST_WIDE_INT offset,
> > - scalar_int_mode mode)
> > + machine_mode mode)
> > {
> > tree str = (tree) data;
> >
> > @@ -5762,17 +5819,19 @@ string_cst_read_str (void *data, void *,
> > HOST_WIDE_INT offset,
> > if (offset >= TREE_STRING_LENGTH (str))
> > return const0_rtx;
> >
> > - if ((unsigned HOST_WIDE_INT) offset + GET_MODE_SIZE (mode)
> > + unsigned int size = GET_MODE_SIZE (mode).to_constant ();
> > + if ((unsigned HOST_WIDE_INT) offset + size
> > > (unsigned HOST_WIDE_INT) TREE_STRING_LENGTH (str))
> > {
> > - char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
> > + char *p = XALLOCAVEC (char, size);
> > size_t l = TREE_STRING_LENGTH (str) - offset;
> > memcpy (p, TREE_STRING_POINTER (str) + offset, l);
> > - memset (p + l, '\0', GET_MODE_SIZE (mode) - l);
> > - return c_readstr (p, mode, false);
> > + memset (p + l, '\0', size - l);
> > + return c_readstr (p, as_a <scalar_int_mode> (mode), false);
> > }
> >
> > - return c_readstr (TREE_STRING_POINTER (str) + offset, mode, false);
> > + return c_readstr (TREE_STRING_POINTER (str) + offset,
> > + as_a <scalar_int_mode> (mode), false);
> > }
> >
> > /* Generate code for computing expression EXP,
> > diff --git a/gcc/expr.h b/gcc/expr.h
> > index a4f44265759..552645e4403 100644
> > --- a/gcc/expr.h
> > +++ b/gcc/expr.h
> > @@ -108,13 +108,13 @@ enum block_op_methods
> > };
> >
> > typedef rtx (*by_pieces_constfn) (void *, void *, HOST_WIDE_INT,
> > - scalar_int_mode);
> > + machine_mode);
> >
> > /* The second pointer passed to by_pieces_constfn. */
> > struct by_pieces_prev
> > {
> > rtx data;
> > - scalar_int_mode mode;
> > + machine_mode mode;
> > };
> >
> > extern rtx emit_block_move (rtx, rtx, rtx, enum block_op_methods);
> > diff --git a/gcc/target.def b/gcc/target.def
> > index 2e40448e6c5..cc4aa3a4212 100644
> > --- a/gcc/target.def
> > +++ b/gcc/target.def
> > @@ -2726,6 +2726,13 @@ DEFHOOK
> > rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code,
> > tree op0, tree op1, int bit_code),
> > NULL)
> >
> > +DEFHOOK
> > +(gen_memset_scratch_rtx,
> > + "This hook should return an rtx for scratch register in @var{mode} to\n\
> > +be used by memset broadcast. The default is @code{gen_reg_rtx}.",
> > + rtx, (machine_mode mode),
> > + gen_reg_rtx)
> > +
> > /* Return a new value for loop unroll size. */
> > DEFHOOK
> > (loop_unroll_adjust,
> > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-3.c
> > b/gcc/testsuite/gcc.target/i386/pr100865-3.c
> > index b6dbcf7809b..007e79f91b0 100644
> > --- a/gcc/testsuite/gcc.target/i386/pr100865-3.c
> > +++ b/gcc/testsuite/gcc.target/i386/pr100865-3.c
> > @@ -10,6 +10,6 @@ foo (void)
> > }
> >
> > /* { dg-final { scan-assembler-times "vpbroadcastb\[\\t
> > \]+%(?:r|e)\[^\n\]*, %xmm\[0-9\]+" 1 } } */
> > -/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+,
> > \\(%\[\^,\]+\\)" 1 } } */
> > +/* { dg-final { scan-assembler-times "vmovdqu8\[\\t \]%xmm\[0-9\]+,
> > \\(%\[\^,\]+\\)" 1 } } */
> > /* { dg-final { scan-assembler-not "vpbroadcastb\[\\t \]+%xmm\[0-9\]+,
> > %xmm\[0-9\]+" } } */
> > /* { dg-final { scan-assembler-not "vmovdqa" } } */
> > diff --git a/gcc/testsuite/gcc.target/i386/pr100865-4b.c
> > b/gcc/testsuite/gcc.target/i386/pr100865-4b.c
> > index f41e6147b4c..1e50dc842bc 100644
> > --- a/gcc/testsuite/gcc.target/i386/pr100865-4b.c
> > +++ b/gcc/testsuite/gcc.target/i386/pr100865-4b.c
> > @@ -4,6 +4,6 @@
> > #include "pr100865-4a.c"
> >
> > /* { dg-final { scan-assembler-times "vpbroadcastb\[\\t
> > \]+%(?:r|e)\[^\n\]*, %xmm\[0-9\]+" 1 } } */
> > -/* { dg-final { scan-assembler-times "vmovdqu\[\\t \]%xmm\[0-9\]+, " 4 } }
> > */
> > +/* { dg-final { scan-assembler-times "vmovdqu8\[\\t \]%xmm\[0-9\]+, " 4 }
> > } */
> > /* { dg-final { scan-assembler-not "vpbroadcastb\[\\t \]+%xmm\[0-9\]+,
> > %xmm\[0-9\]+" } } */
> > /* { dg-final { scan-assembler-not "vmovdqa" } } */
--
H.J.
