File _service:tar_scm:strcmp-delete-align-for-loop_a... of Package glibc

File _service:tar_scm:strcmp-delete-align-for-loop_aligned.patch of Package glibc (Revision f88d6887443205b639a7b80f8e573606)

Currently displaying revision f88d6887443205b639a7b80f8e573606 , Show latest

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