On Wed, May 26, 2021 at 10:28:16AM +0200, Richard Biener wrote:
> > > >
> > > > -- 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
>
> Not sure what I should read from there...
>
> > 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.
>
> OK, I guess I'm not (RTL) qualified enough to further review these parts,
> sorry. Since we're doing code generation the canonical way to communicate
> with backends should be optabs, not some set of disconnected target hooks.
> But as said, I probably don't know enough of RTL to see why it's the only way.
>
> Richard.
Here is the patch to add optabs instead. Does it look OK?
Thanks.
H.J.
---
Add 2 optabs:
1. integer_extract: Extract lower bit value from the integer value in
TImode, OImode or XImode.
2. vec_const_duplicate: Broadcast a QImode constant to a vector. It is
similar to vec_duplicate. Since the resulting vector is computable at
compile-time, vec_duplicate may not be faster and backend can opt out
broadcasting from a constant while opting in broadcasting from a
variable.
and rewrite builtin_memset_read_str/builtin_memset_gen_str to support
target instructions to duplicate QImode value to TImode, OImode or XImode
value for memmset.
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.
* optabs.def: Add integer_extract and vec_const_duplicate.
* target.def (gen_memset_scratch_rtx): New hook.
* doc/md.texi: Document vec_const_duplicate and integer_extract.
* doc/tm.texi.in: Add TARGET_GEN_MEMSET_SCRATCH_RTX.
* doc/tm.texi: Regenerated.
---
gcc/builtins.c | 117 +++++++++++++++++++++++++++++++++++++--------
gcc/doc/md.texi | 16 +++++++
gcc/doc/tm.texi | 5 ++
gcc/doc/tm.texi.in | 2 +
gcc/optabs.def | 4 ++
gcc/target.def | 7 +++
6 files changed, 131 insertions(+), 20 deletions(-)
diff --git a/gcc/builtins.c b/gcc/builtins.c
index af1fe49bb48..7683169eb96 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -6598,26 +6598,106 @@ expand_builtin_strncpy (tree exp, rtx target)
return NULL_RTX;
}
+/* 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)
+{
+ 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;
+
+ /* Extract the RTL in MODE from PREV. */
+ enum insn_code icode
+ = convert_optab_handler (integer_extract_optab, mode,
+ prev->mode);
+ if (icode != CODE_FOR_nothing)
+ {
+ target = gen_reg_rtx (mode);
+ class expand_operand ops[2];
+ create_output_operand (&ops[0], target, mode);
+ create_input_operand (&ops[1], prev->data, prev->mode);
+ expand_insn (icode, 2, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
+ }
+ else
+ target = simplify_gen_subreg (mode, prev->data, prev->mode, 0);
+ }
+ return target;
+}
+
+/* Return the RTL of a register in MODE broadcasted from DATA. */
+
+static rtx
+gen_memset_broadcast (enum optab_tag broadcast_optab, 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 ();
+
+ enum insn_code icode = optab_handler (broadcast_optab, vector_mode);
+ if (icode != CODE_FOR_nothing)
+ {
+ target = targetm.gen_memset_scratch_rtx (vector_mode);
+ class expand_operand ops[2];
+ create_output_operand (&ops[0], target, vector_mode);
+ create_input_operand (&ops[1], (rtx) data, QImode);
+ expand_insn (icode, 2, ops);
+ if (!rtx_equal_p (target, ops[0].value))
+ emit_move_insn (target, ops[0].value);
+ if (REGNO (target) < FIRST_PSEUDO_REGISTER)
+ target = gen_rtx_REG (mode, REGNO (target));
+ else
+ target = convert_to_mode (mode, target, 1);
+ }
+
+ 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 *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)
+ rtx target;
+
+ /* Don't use the previous value if size is 1. */
+ if (GET_MODE_SIZE (mode) != 1)
{
- /* Use the previous data in the same mode. */
- if (prev->mode == mode)
- return prev->data;
+ target = gen_memset_value_from_prev (prev, mode);
+ if (target != nullptr)
+ return target;
}
const char *c = (const char *) data;
- char *p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
+ char *p = XALLOCAVEC (char, GET_MODE_SIZE (QImode));
+ memset (p, *c, GET_MODE_SIZE (QImode));
+ rtx src = c_readstr (p, QImode);
+ target = gen_memset_broadcast (vec_const_duplicate_optab, src,
+ mode);
+ if (target != nullptr)
+ return target;
+
+ p = XALLOCAVEC (char, GET_MODE_SIZE (mode));
memset (p, *c, GET_MODE_SIZE (mode));
@@ -6631,7 +6711,7 @@ 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)
{
@@ -6639,22 +6719,19 @@ builtin_memset_gen_str (void *data, void *prevp,
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;
+ target = gen_memset_value_from_prev (prev, mode);
+ if (target != nullptr)
+ return target;
+
+ target = gen_memset_broadcast (vec_duplicate_optab, (rtx) data,
+ mode);
+ if (target != nullptr)
+ return target;
+
p = XALLOCAVEC (char, size);
memset (p, 1, size);
coeff = c_readstr (p, mode);
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 00caf3844cc..a798fb1a97e 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -5079,6 +5079,16 @@ vectors go through the @code{mov@var{m}} pattern instead.
This pattern is not allowed to @code{FAIL}.
+@cindex @code{vec_const_duplicate@var{m}} instruction pattern
+@item @samp{vec_const_duplicate@var{m}}
+Initialize vector output operand 0 in mode @var{m} so that each element
+has the value given by constant input operand 1.
+
+This pattern only handles duplicates of constant inputs. Non-constant
+vectors go through the @code{vec_duplicate@var{m}} pattern instead.
+
+This pattern is not allowed to @code{FAIL}.
+
@cindex @code{vec_series@var{m}} instruction pattern
@item @samp{vec_series@var{m}}
Initialize vector output operand 0 so that element @var{i} is equal to
@@ -7904,6 +7914,12 @@ inclusive and operand 1 exclusive.
If this pattern is not defined, a call to the library function
@code{__clear_cache} is used.
+@cindex @code{integer_extract@var{m}@var{n}} instruction pattern
+@item @samp{integer_extract@var{m}@var{n}}
+Extract lower bit value from the integer value in @code{TImode},
+@code{OImode} or @code{XImode}. Operand 1 is the integer in mode
+@var{n} and operand 0 stores value to be extracted in mode @var{m}.
+
@end table
@end ifset
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index e3a080e4a7c..8ccc262b1fc 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -11894,6 +11894,11 @@ 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}.
+@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 d9fbbe20e6f..99bf01fe25d 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -7960,6 +7960,8 @@ 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/optabs.def b/gcc/optabs.def
index b192a9d070b..fd8ab8b4a26 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -100,6 +100,8 @@ OPTAB_CD(vec_init_optab, "vec_init$a$b")
OPTAB_CD (while_ult_optab, "while_ult$a$b")
+OPTAB_CD (integer_extract_optab, "integer_extract$a$b")
+
OPTAB_NL(add_optab, "add$P$a3", PLUS, "add", '3', gen_int_fp_fixed_libfunc)
OPTAB_NX(add_optab, "add$F$a3")
OPTAB_NX(add_optab, "add$Q$a3")
@@ -453,3 +455,5 @@ OPTAB_DC (vec_series_optab, "vec_series$a", VEC_SERIES)
OPTAB_D (vec_shl_insert_optab, "vec_shl_insert_$a")
OPTAB_D (len_load_optab, "len_load_$a")
OPTAB_D (len_store_optab, "len_store_$a")
+
+OPTAB_DC (vec_const_duplicate_optab, "vec_const_duplicate$a", VEC_DUPLICATE)
diff --git a/gcc/target.def b/gcc/target.def
index 1dffedc81e4..b89e7c24471 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -2724,6 +2724,13 @@ 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,
--
2.31.1
