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From 9bbffed83b93f633b272368fc536a4f24e9942e6 Mon Sep 17 00:00:00 2001
From: Yang Yanchao <yangyanchao6@huawei.com>
Date: Mon, 21 Feb 2022 14:25:25 +0800
Subject: [PATCH] strcmp: delete align for loop_aligned
In Kunpeng-920, the performance of strcmp deteriorates only
when the 16 to 23 characters are different.Or the string is
only 16-23 characters.That shows 2 misses per iteration which
means this is a branch predictor issue indeed.
In the preceding scenario, strcmp performance is 300% worse than expected.
Fortunately, this problem can be solved by modifying the alignment of the functions.
---
sysdeps/aarch64/strcmp.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/sysdeps/aarch64/strcmp.S b/sysdeps/aarch64/strcmp.S
index f225d718..7a048b66 100644
--- a/sysdeps/aarch64/strcmp.S
+++ b/sysdeps/aarch64/strcmp.S
@@ -71,8 +71,6 @@ ENTRY(strcmp)
b.ne L(misaligned8)
cbnz tmp, L(mutual_align)
- .p2align 4
-
L(loop_aligned):
ldr data2, [src1, off2]
ldr data1, [src1], 8
--
2.33.0
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