From: Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp>
To: GCC Patches <gcc-patches@gcc.gnu.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH] xtensa: Make instruction cost estimation for size more accurate
Date: Tue, 10 Jan 2023 12:34:01 +0900 [thread overview]
Message-ID: <2203c450-66c4-f100-2fc1-ab7e45cc008f@yahoo.co.jp> (raw)
In-Reply-To: <2203c450-66c4-f100-2fc1-ab7e45cc008f.ref@yahoo.co.jp>
Until now, we applied COSTS_N_INSNS() (multiplying by 4) after dividing
the instruction length by 3, so we couldn't express the difference less
than modulo 3 in insn cost for size (e.g. 11 Bytes and 12 bytes cost the
same).
This patch fixes that.
;; 2 bytes
addi.n a2, a2, -1 ; cost 3
;; 3 bytes
addmi a2, a2, 1024 ; cost 4
;; 4 bytes
movi.n a3, 80 ; cost 5
bnez.n a2, a3, .L4
;; 5 bytes
srli a2, a3, 1 ; cost 7
add.n a2, a2, a2
;; 6 bytes
ssai 8 ; cost 8
src a4, a2, a3
:: 3 + 4 bytes
l32r a2, .L5 ; cost 9
;; 11 bytes ; cost 15
;; 12 bytes ; cost 16
gcc/ChangeLog:
* config/xtensa/xtensa.cc (xtensa_insn_cost):
Let insn cost for size be obtained by applying COSTS_N_INSNS()
to instruction length and then dividing by 3.
---
gcc/config/xtensa/xtensa.cc | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index a1f184950ae..6cf6b35399a 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -4519,13 +4519,15 @@ xtensa_insn_cost (rtx_insn *insn, bool speed)
{
if (!(recog_memoized (insn) < 0))
{
- int len = get_attr_length (insn), n = (len + 2) / 3;
+ int len = get_attr_length (insn);
if (len == 0)
return COSTS_N_INSNS (0);
if (speed) /* For speed cost. */
{
+ int n = (len + 2) / 3;
+
/* "L32R" may be particular slow (implementation-dependent). */
if (xtensa_is_insn_L32R_p (insn))
return COSTS_N_INSNS (1 + xtensa_extra_l32r_costs);
@@ -4572,10 +4574,11 @@ xtensa_insn_cost (rtx_insn *insn, bool speed)
{
/* "L32R" itself plus constant in litpool. */
if (xtensa_is_insn_L32R_p (insn))
- return COSTS_N_INSNS (2) + 1;
+ len = 3 + 4;
- /* Consider ".n" short instructions. */
- return COSTS_N_INSNS (n) - (n * 3 - len);
+ /* Consider fractional instruction length (for example, ".n"
+ short instructions or "L32R" litpool constants. */
+ return (COSTS_N_INSNS (len) + 1) / 3;
}
}
}
--
2.30.2
next parent reply other threads:[~2023-01-10 3:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2203c450-66c4-f100-2fc1-ab7e45cc008f.ref@yahoo.co.jp>
2023-01-10 3:34 ` Takayuki 'January June' Suwa [this message]
2023-01-11 5:55 ` Max Filippov
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