* [PATCH 1/2] xtensa: constantsynth: Make try to find shorter instruction
@ 2022-07-15 10:50 Takayuki 'January June' Suwa
2022-07-16 7:29 ` Max Filippov
0 siblings, 1 reply; 2+ messages in thread
From: Takayuki 'January June' Suwa @ 2022-07-15 10:50 UTC (permalink / raw)
To: GCC Patches
This patch allows the constant synthesis to choose shorter instruction
if possible.
/* example */
int test(void) {
return 128 << 8;
}
;; before
test:
movi a2, 0x100
addmi a2, a2, 0x7f00
ret.n
;; after
test:
movi.n a2, 1
slli a2, a2, 15
ret.n
When the Code Density Option is configured, the latter is one byte smaller
than the former.
gcc/ChangeLog:
* config/xtensa/xtensa.cc (xtensa_emit_constantsynth): Remove.
(xtensa_constantsynth_2insn): Change to try all three synthetic
methods and to use the one that fits the immediate value of
the seed into a Narrow Move Immediate instruction "MOVI.N"
when the Code Density Option is configured.
---
gcc/config/xtensa/xtensa.cc | 58 ++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 29 deletions(-)
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index 13f2b2b832c..94337452ba8 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -1035,35 +1035,35 @@ xtensa_split_operand_pair (rtx operands[4], machine_mode mode)
load-immediate / arithmetic ones, instead of a L32R instruction
(plus a constant in litpool). */
-static void
-xtensa_emit_constantsynth (rtx dst, enum rtx_code code,
- HOST_WIDE_INT imm0, HOST_WIDE_INT imm1,
- rtx (*gen_op)(rtx, HOST_WIDE_INT),
- HOST_WIDE_INT imm2)
-{
- gcc_assert (REG_P (dst));
- emit_move_insn (dst, GEN_INT (imm0));
- emit_move_insn (dst, gen_rtx_fmt_ee (code, SImode,
- dst, GEN_INT (imm1)));
- if (gen_op)
- emit_move_insn (dst, gen_op (dst, imm2));
-}
-
static int
xtensa_constantsynth_2insn (rtx dst, HOST_WIDE_INT srcval,
rtx (*gen_op)(rtx, HOST_WIDE_INT),
HOST_WIDE_INT op_imm)
{
- int shift = exact_log2 (srcval + 1);
+ HOST_WIDE_INT imm = INT_MAX;
+ rtx x = NULL_RTX;
+ int shift;
+ gcc_assert (REG_P (dst));
+
+ shift = exact_log2 (srcval + 1);
if (IN_RANGE (shift, 1, 31))
{
- xtensa_emit_constantsynth (dst, LSHIFTRT, -1, 32 - shift,
- gen_op, op_imm);
- return 1;
+ imm = -1;
+ x = gen_lshrsi3 (dst, dst, GEN_INT (32 - shift));
}
- if (IN_RANGE (srcval, (-2048 - 32768), (2047 + 32512)))
+
+ shift = ctz_hwi (srcval);
+ if ((!x || (TARGET_DENSITY && ! IN_RANGE (imm, -32, 95)))
+ && xtensa_simm12b (srcval >> shift))
+ {
+ imm = srcval >> shift;
+ x = gen_ashlsi3 (dst, dst, GEN_INT (shift));
+ }
+
+ if ((!x || (TARGET_DENSITY && ! IN_RANGE (imm, -32, 95)))
+ && IN_RANGE (srcval, (-2048 - 32768), (2047 + 32512)))
{
HOST_WIDE_INT imm0, imm1;
@@ -1076,19 +1076,19 @@ xtensa_constantsynth_2insn (rtx dst, HOST_WIDE_INT srcval,
imm0 = srcval - imm1;
if (TARGET_DENSITY && imm1 < 32512 && IN_RANGE (imm0, 224, 255))
imm0 -= 256, imm1 += 256;
- xtensa_emit_constantsynth (dst, PLUS, imm0, imm1, gen_op, op_imm);
- return 1;
+ imm = imm0;
+ x = gen_addsi3 (dst, dst, GEN_INT (imm1));
}
- shift = ctz_hwi (srcval);
- if (xtensa_simm12b (srcval >> shift))
- {
- xtensa_emit_constantsynth (dst, ASHIFT, srcval >> shift, shift,
- gen_op, op_imm);
- return 1;
- }
+ if (!x)
+ return 0;
- return 0;
+ emit_move_insn (dst, GEN_INT (imm));
+ emit_insn (x);
+ if (gen_op)
+ emit_move_insn (dst, gen_op (dst, op_imm));
+
+ return 1;
}
static rtx
--
2.20.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 1/2] xtensa: constantsynth: Make try to find shorter instruction
2022-07-15 10:50 [PATCH 1/2] xtensa: constantsynth: Make try to find shorter instruction Takayuki 'January June' Suwa
@ 2022-07-16 7:29 ` Max Filippov
0 siblings, 0 replies; 2+ messages in thread
From: Max Filippov @ 2022-07-16 7:29 UTC (permalink / raw)
To: Takayuki 'January June' Suwa; +Cc: GCC Patches
On Fri, Jul 15, 2022 at 4:17 PM Takayuki 'January June' Suwa
<jjsuwa_sys3175@yahoo.co.jp> wrote:
>
> This patch allows the constant synthesis to choose shorter instruction
> if possible.
>
> /* example */
> int test(void) {
> return 128 << 8;
> }
>
> ;; before
> test:
> movi a2, 0x100
> addmi a2, a2, 0x7f00
> ret.n
>
> ;; after
> test:
> movi.n a2, 1
> slli a2, a2, 15
> ret.n
>
> When the Code Density Option is configured, the latter is one byte smaller
> than the former.
>
> gcc/ChangeLog:
>
> * config/xtensa/xtensa.cc (xtensa_emit_constantsynth): Remove.
> (xtensa_constantsynth_2insn): Change to try all three synthetic
> methods and to use the one that fits the immediate value of
> the seed into a Narrow Move Immediate instruction "MOVI.N"
> when the Code Density Option is configured.
> ---
> gcc/config/xtensa/xtensa.cc | 58 ++++++++++++++++++-------------------
> 1 file changed, 29 insertions(+), 29 deletions(-)
Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master.
--
Thanks.
-- Max
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-07-16 7:29 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-07-15 10:50 [PATCH 1/2] xtensa: constantsynth: Make try to find shorter instruction Takayuki 'January June' Suwa
2022-07-16 7:29 ` Max Filippov
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).