|
 |
c5d972 |
From 1d9f99ce1b3788d1897cb53a76d57e973111b8fe Mon Sep 17 00:00:00 2001
|
|
|
c5d972 |
From: Naohiro Tamura <naohirot@fujitsu.com>
|
|
|
c5d972 |
Date: Fri, 27 Aug 2021 05:03:04 +0000
|
|
|
c5d972 |
Subject: [PATCH] AArch64: Update A64FX memset not to degrade at 16KB
|
|
|
c5d972 |
|
|
|
c5d972 |
This patch updates unroll8 code so as not to degrade at the peak
|
|
|
c5d972 |
performance 16KB for both FX1000 and FX700.
|
|
|
c5d972 |
|
|
|
c5d972 |
Inserted 2 instructions at the beginning of the unroll8 loop,
|
|
|
c5d972 |
cmp and branch, are a workaround that is found heuristically.
|
|
|
c5d972 |
|
|
|
c5d972 |
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
|
|
|
c5d972 |
---
|
|
|
c5d972 |
sysdeps/aarch64/multiarch/memset_a64fx.S | 9 ++++++++-
|
|
|
c5d972 |
1 file changed, 8 insertions(+), 1 deletion(-)
|
|
|
c5d972 |
|
|
|
c5d972 |
diff --git a/sysdeps/aarch64/multiarch/memset_a64fx.S b/sysdeps/aarch64/multiarch/memset_a64fx.S
|
|
|
c5d972 |
index 7bf759b6a7..f7dfdaace7 100644
|
|
|
c5d972 |
--- a/sysdeps/aarch64/multiarch/memset_a64fx.S
|
|
|
c5d972 |
+++ b/sysdeps/aarch64/multiarch/memset_a64fx.S
|
|
|
c5d972 |
@@ -96,7 +96,14 @@ L(vl_agnostic): // VL Agnostic
|
|
|
c5d972 |
L(unroll8):
|
|
|
c5d972 |
sub count, count, tmp1
|
|
|
c5d972 |
.p2align 4
|
|
|
c5d972 |
-1: st1b_unroll 0, 7
|
|
|
c5d972 |
+ // The 2 instructions at the beginning of the following loop,
|
|
|
c5d972 |
+ // cmp and branch, are a workaround so as not to degrade at
|
|
|
c5d972 |
+ // the peak performance 16KB.
|
|
|
c5d972 |
+ // It is found heuristically and the branch condition, b.ne,
|
|
|
c5d972 |
+ // is chosen intentionally never to jump.
|
|
|
c5d972 |
+1: cmp xzr, xzr
|
|
|
c5d972 |
+ b.ne 1b
|
|
|
c5d972 |
+ st1b_unroll 0, 7
|
|
|
c5d972 |
add dst, dst, tmp1
|
|
|
c5d972 |
subs count, count, tmp1
|
|
|
c5d972 |
b.hi 1b
|
|
|
c5d972 |
--
|
|
|
c5d972 |
2.31.1
|
|
|
c5d972 |
|