Re: [PATCH] Rewrite memset expanders with vec_duplicate
On Fri, Jul 16, 2021 at 6:24 AM Richard Sandiford
wrote:
>
> "H.J. Lu via Gcc-patches" writes:
> > On Fri, Jul 16, 2021 at 4:38 AM Richard Sandiford
> > wrote:
> >>
> >> "H.J. Lu via Gcc-patches" 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 (_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
Re: [PATCH] Rewrite memset expanders with vec_duplicate
"H.J. Lu via Gcc-patches" writes:
> On Fri, Jul 16, 2021 at 4:38 AM Richard Sandiford
> wrote:
>>
>> "H.J. Lu via Gcc-patches" 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 (_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
Re: [PATCH] Rewrite memset expanders with vec_duplicate
On Fri, Jul 16, 2021 at 4:38 AM Richard Sandiford
wrote:
>
> "H.J. Lu via Gcc-patches" 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 (_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.
> 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?
Thanks.
> Thanks,
> Richard
>
> > +
> > + enum insn_code icode = optab_handler (vec_duplicate_optab,
> > + vector_mode);
> > + if (icode != CODE_FOR_nothing)
> > +{
> > + rtx reg = targetm.gen_memset_scratch_rtx
Re: [PATCH] Rewrite memset expanders with vec_duplicate
"H.J. Lu via Gcc-patches" 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 (_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.
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.
Thanks,
Richard
> +
> + enum insn_code icode = optab_handler (vec_duplicate_optab,
> + vector_mode);
> + if (icode != CODE_FOR_nothing)
> +{
> + rtx reg = targetm.gen_memset_scratch_rtx (vector_mode);
> + if (CONST_INT_P (data))
> + {
> + /* Use the move expander with CONST_VECTOR. */
> + rtx const_vec = gen_const_vec_duplicate (vector_mode, data);
> + emit_move_insn (reg, const_vec);
> + }
> + else
> + {
> +
> + class expand_operand ops[2];
> + create_output_operand ([0], reg, vector_mode);
> + create_input_operand ([1], data, QImode);
> + expand_insn (icode, 2, ops);
> + if (!rtx_equal_p (reg, ops[0].value))
> + emit_move_insn (reg, ops[0].value);
> + }
> + target = lowpart_subreg (mode, reg, vector_mode);
> +}
> +
> + 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,
> + scalar_int_mode
[PATCH] Rewrite memset expanders with vec_duplicate
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 (_mode))
+gcc_unreachable ();
+
+ enum insn_code icode = optab_handler (vec_duplicate_optab,
+ vector_mode);
+ if (icode != CODE_FOR_nothing)
+{
+ rtx reg = targetm.gen_memset_scratch_rtx (vector_mode);
+ if (CONST_INT_P (data))
+ {
+ /* Use the move expander with CONST_VECTOR. */
+ rtx const_vec = gen_const_vec_duplicate (vector_mode, data);
+ emit_move_insn (reg, const_vec);
+ }
+ else
+ {
+
+ class expand_operand ops[2];
+ create_output_operand ([0], reg, vector_mode);
+ create_input_operand ([1], data, QImode);
+ expand_insn (icode, 2, ops);
+ if (!rtx_equal_p (reg, ops[0].value))
+ emit_move_insn (reg, ops[0].value);
+ }
+ target = lowpart_subreg (mode, reg, vector_mode);
+}
+
+ 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,
+scalar_int_mode mode)
+{
+ rtx target;
const char *c = (const char *) data;
- char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
+ char *p;
+
+ /* Don't use the previous value if size is 1. */
+ if (GET_MODE_SIZE (mode) != 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);
+ target = gen_memset_broadcast (src, mode);
+ if (target != nullptr)
+ return target;
+}
+
+ p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
memset (p, *c, GET_MODE_SIZE (mode));
