[PATCH] Rewrite memset expanders with vec_duplicate
H.J. Lu
hjl.tools@gmail.com
Tue Jul 13 21:49:56 GMT 2021
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 ();
+
+ 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 (&ops[0], reg, vector_mode);
+ create_input_operand (&ops[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));
@@ -6719,7 +6804,7 @@ 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)
{
@@ -6727,22 +6812,18 @@ 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 ((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/tm.texi b/gcc/doc/tm.texi
index 2a41ae5fba1..8849711fcf8 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -12122,6 +12122,11 @@ 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 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/target.def b/gcc/target.def
index c009671c583..5fb287db3bd 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,
--
2.31.1
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