On Tue, May 25, 2021 at 7:34 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Thu, May 20, 2021 at 10:50 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> >
> > On Wed, May 19, 2021 at 5:55 AM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > On Wed, May 19, 2021 at 2:25 AM Richard Biener
> > > <richard.guent...@gmail.com> wrote:
> > > >
> > > > On Tue, May 18, 2021 at 9:16 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > > > >
> > > > > Add TARGET_READ_MEMSET_VALUE and TARGET_GEN_MEMSET_VALUE to support
> > > > > target instructions to duplicate QImode value to TImode/OImode/XImode
> > > > > value for memmset.
> > > > >
> > > > > PR middle-end/90773
> > > > > * builtins.c (builtin_memset_read_str): Call
> > > > > targetm.read_memset_value.
> > > > > (builtin_memset_gen_str): Call targetm.gen_memset_value.
> > > > > * target.def (read_memset_value): New hook.
> > > > > (gen_memset_value): Likewise.
> > > > > * targhooks.c: Inclue "builtins.h".
> > > > > (default_read_memset_value): New function.
> > > > > (default_gen_memset_value): Likewise.
> > > > > * targhooks.h (default_read_memset_value): New prototype.
> > > > > (default_gen_memset_value): Likewise.
> > > > > * doc/tm.texi.in: Add TARGET_READ_MEMSET_VALUE and
> > > > > TARGET_GEN_MEMSET_VALUE hooks.
> > > > > * doc/tm.texi: Regenerated.
> > > > > ---
> > > > > gcc/builtins.c | 47 ++++----------------------------------
> > > > > gcc/doc/tm.texi | 16 +++++++++++++
> > > > > gcc/doc/tm.texi.in | 4 ++++
> > > > > gcc/target.def | 20 +++++++++++++++++
> > > > > gcc/targhooks.c | 56
> > > > > ++++++++++++++++++++++++++++++++++++++++++++++
> > > > > gcc/targhooks.h | 4 ++++
> > > > > 6 files changed, 104 insertions(+), 43 deletions(-)
> > > > >
> > > > > diff --git a/gcc/builtins.c b/gcc/builtins.c
> > > > > index e1b284846b1..f78a36478ef 100644
> > > > > --- a/gcc/builtins.c
> > > > > +++ b/gcc/builtins.c
> > > > > @@ -6584,24 +6584,11 @@ expand_builtin_strncpy (tree exp, rtx target)
> > > > > previous iteration. */
> > > > >
> > > > > rtx
> > > > > -builtin_memset_read_str (void *data, void *prevp,
> > > > > +builtin_memset_read_str (void *data, void *prev,
> > > > > 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;
> > > > > - }
> > > > > -
> > > > > - const char *c = (const char *) data;
> > > > > - char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
> > > > > -
> > > > > - memset (p, *c, GET_MODE_SIZE (mode));
> > > > > -
> > > > > - return c_readstr (p, mode);
> > > > > + return targetm.read_memset_value ((const char *) data, prev, mode);
> > > > > }
> > > > >
> > > > > /* Callback routine for store_by_pieces. Return the RTL of a
> > > > > register
> > > > > @@ -6611,37 +6598,11 @@ 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)
> > > > > {
> > > > > - 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);
> > > > > - if (size == 1)
> > > > > - return (rtx) data;
> > > > > -
> > > > > - p = XALLOCAVEC (char, size);
> > > > > - memset (p, 1, size);
> > > > > - coeff = c_readstr (p, mode);
> > > > > -
> > > > > - target = convert_to_mode (mode, (rtx) data, 1);
> > > > > - target = expand_mult (mode, target, coeff, NULL_RTX, 1);
> > > > > - return force_reg (mode, target);
> > > > > + return targetm.gen_memset_value ((rtx) data, prev, mode);
> > > > > }
> > > > >
> > > > > /* Expand expression EXP, which is a call to the memset builtin.
> > > > > Return
> > > > > diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> > > > > index 85ea9395560..51385044e76 100644
> > > > > --- a/gcc/doc/tm.texi
> > > > > +++ b/gcc/doc/tm.texi
> > > > > @@ -11868,6 +11868,22 @@ 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_READ_MEMSET_VALUE (const char
> > > > > *@var{c}, void *@var{prev}, scalar_int_mode @var{mode})
> > > > > +This function returns the RTL of a constant integer corresponding to
> > > > > +target reading @code{GET_MODE_SIZE (@var{mode})} bytes from the
> > > > > stringn
> > > > > +constant @var{str}. If @var{prev} is not @samp{nullptr}, it contains
> > > > > +the RTL information from the previous interation.
> > > > > +@end deftypefn
> > > > > +
> > > > > +@deftypefn {Target Hook} rtx TARGET_GEN_MEMSET_VALUE (rtx
> > > > > @var{data}, void *@var{prev}, scalar_int_mode @var{mode})
> > > > > +This function returns the RTL of a register containing
> > > > > +@code{GET_MODE_SIZE (@var{mode})} consecutive copies of the unsigned
> > > > > +char value given in the RTL register @var{data}. For example, if
> > > > > +@var{mode} is 4 bytes wide, return the RTL for 0x01010101*@var{data}.
> > > > > +If @var{PREV} is not @samp{nullptr}, it is the RTL information from
> > > > > +the previous iteration.
> > > > > +@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 d8e3de14af1..8d4c3949fbf 100644
> > > > > --- a/gcc/doc/tm.texi.in
> > > > > +++ b/gcc/doc/tm.texi.in
> > > > > @@ -7956,6 +7956,10 @@ lists.
> > > > >
> > > > > @hook TARGET_GEN_CCMP_NEXT
> > > > >
> > > > > +@hook TARGET_READ_MEMSET_VALUE
> > > > > +
> > > > > +@hook TARGET_GEN_MEMSET_VALUE
> > > > > +
> > > > > @hook TARGET_LOOP_UNROLL_ADJUST
> > > > >
> > > > > @defmac POWI_MAX_MULTS
> > > > > diff --git a/gcc/target.def b/gcc/target.def
> > > > > index bbaf6b4f3a0..c9aca40fa88 100644
> > > > > --- a/gcc/target.def
> > > > > +++ b/gcc/target.def
> > > > > @@ -2694,6 +2694,26 @@ DEFHOOK
> > > > > rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int
> > > > > cmp_code, tree op0, tree op1, int bit_code),
> > > > > NULL)
> > > > >
> > > > > +DEFHOOK
> > > > > +(read_memset_value,
> > > > > + "This function returns the RTL of a constant integer corresponding
> > > > > to\n\
> > > > > +target reading @code{GET_MODE_SIZE (@var{mode})} bytes from the
> > > > > stringn\n\
> > > > > +constant @var{str}. If @var{prev} is not @samp{nullptr}, it
> > > > > contains\n\
> > > >
> > > > where is 'str' defined? I can't really tell what's the difference
> > >
> > > Fixed with
> > >
> > > diff --git a/gcc/target.def b/gcc/target.def
> > > index c9aca40fa88..4c3a5fcc634 100644
> > > --- a/gcc/target.def
> > > +++ b/gcc/target.def
> > > @@ -2699,8 +2699,8 @@ DEFHOOK
> > > "This function returns the RTL of a constant integer corresponding to\n\
> > > target reading @code{GET_MODE_SIZE (@var{mode})} bytes from the string\n\
> > > constant @var{str}. If @var{prev} is not @samp{nullptr}, it contains\n\
> > > -the RTL information from the previous interation.",
> > > - rtx, (const char *c, void *prev, scalar_int_mode mode),
> > > +the RTL information from the previous iteration.",
> > > + rtx, (const char *str, void *prev, scalar_int_mode mode),
> > > default_read_memset_value)
> > >
> > > DEFHOOK
> > >
> > > > from read_memset_value
> > > > and gen_memset_value.
> > >
> > > The difference is that input of read_memset_value is a string constant
> > > like "123" and input of gen_memset_value is an RTL register.
> > >
> > > > Somehow I feel that an optab for the "splat" operation similar
> > > > to vec_duplicate might be a better way to expose this - of course
> > > > that doesn't handle the "prev" thing.
> > >
> > > The x86 backend has ix86_expand_vector_init_duplicate () to
> > > broadcast QImode to TImode/OImode/XImode:
> > >
> > > /* A subroutine of ix86_expand_vector_init. Store into TARGET a vector
> > > with all elements equal to VAR. Return true if successful. */
> > >
> > > bool
> > > ix86_expand_vector_init_duplicate (bool mmx_ok, machine_mode mode,
> > > rtx target, rtx val)
> > >
> > > > So how's this the right point of abstraction to the target?
> > >
> > > I can add 2 target hooks, one for scratch register and one for
> > > broadcasting QImode to TImode/OImode/XImode. Then I can
> > > move x86 codes to the middle-end.
> > >
> >
> > Here is the patch to add 3 target hooks:
> >
> > -- Target Hook: rtx TARGET_READ_MEMSET_VALUE (const char *C,
> > scalar_int_mode MODE)
> > This function returns the RTL of a constant integer corresponding
> > to target reading 'GET_MODE_SIZE (MODE)' bytes from the string
> > constant C.
> >
> > -- Target Hook: rtx TARGET_GEN_MEMSET_VALUE (rtx DATA, scalar_int_mode
> > MODE)
> > This function returns 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.
>
> For this one I wonder if it should be an optab instead. Couldn't you
> use the existing vec_duplicate for this by using (paradoxical) subregs
> like (subreg:TI (vec_duplicate:VnQI (subreg:VnQI (reg:QI ...)))?
I tried. It doesn't even work on x86. See:
https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570661.html
There are special cases to subreg HI, SI and DI modes of TI mode in
ix86_gen_memset_value_from_prev. simplify_gen_subreg doesn't
work here. Each backend may need its own special handling.
> Currently vec_duplicate is only used for SVE IIRC.
>
> > -- Target Hook: rtx TARGET_GEN_MEMSET_VALUE_FROM_PREV (void *PREV,
> > scalar_int_mode MODE)
> > This function returns the RTL of a register in MODE generated from
> > PREV in the previous iteration.
> >
> > with
> >
> > /* Return the RTL of a register in MODE generated from PREV in the
> > previous iteration. */
> >
> > static rtx
> > gen_memset_value_from_prev (void *prevp, scalar_int_mode mode)
> > {
> > by_pieces_prev *prev = (by_pieces_prev *) prevp;
> > rtx value;
> > if (prev != nullptr && prev->data != nullptr)
> > {
> > /* Use the previous data in the same mode. */
> > if (prev->mode == mode)
> > return prev->data;
> >
> > value = targetm.gen_memset_value_from_prev (prevp, mode);
>
> But why do we need a target hook here? Doesn't this just duplicate/subreg
> this further?
See above.
> > }
> > else
> > value = nullptr;
> > return value;
> > }
> >
> > /* 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)
> > {
> > const char *str = (const char *) data;
> >
> > /* Don't use the previous value if size is 1. */
> > if (GET_MODE_SIZE (mode) == 1)
> > return default_read_memset_value (str, mode);
> >
> > rtx value = gen_memset_value_from_prev (prev, mode);
> > if (value)
> > return value;
> >
> > return targetm.read_memset_value (str, mode);
> > }
> >
> > /* 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 *datap, void *prev,
> > HOST_WIDE_INT offset ATTRIBUTE_UNUSED,
> > scalar_int_mode mode)
> > {
> > rtx data = (rtx) datap;
> >
> > /* Don't use the previous value if size is 1. */
> > if (GET_MODE_SIZE (mode) == 1)
> > return data;
> >
> > rtx value = gen_memset_value_from_prev (prev, mode);
> > if (value)
> > return value;
> >
> > return targetm.gen_memset_value (data, mode);
> > }
> >
> >
> > --
> > H.J.
--
H.J.
