[glibc/maskray/unnest] Revert "AArch64: Update A64FX memset not to degrade at 16KB"

[glibc/maskray/unnest] Revert "AArch64: Update A64FX memset not to degrade at 16KB"

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f873adf3df443f8d302677f963adcc3c22187e68

commit f873adf3df443f8d302677f963adcc3c22187e68
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Mon Sep 6 10:21:07 2021 +0100

    Revert "AArch64: Update A64FX memset not to degrade at 16KB"
    
    Because of wrong commit author. Will recommit it with right author.
    
    This reverts commit 23777232c23f80809613bdfa329f63aadf992922.

Diff:
---
 sysdeps/aarch64/multiarch/memset_a64fx.S | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/sysdeps/aarch64/multiarch/memset_a64fx.S b/sysdeps/aarch64/multiarch/memset_a64fx.S
index f7dfdaace7..7bf759b6a7 100644
--- a/sysdeps/aarch64/multiarch/memset_a64fx.S
+++ b/sysdeps/aarch64/multiarch/memset_a64fx.S
@@ -96,14 +96,7 @@ L(vl_agnostic): // VL Agnostic
 L(unroll8):
 	sub	count, count, tmp1
 	.p2align 4
-	// The 2 instructions at the beginning of the following loop,
-	// cmp and branch, are a workaround so as not to degrade at
-	// the peak performance 16KB.
-	// It is found heuristically and the branch condition, b.ne,
-	// is chosen intentionally never to jump.
-1:	cmp	xzr, xzr
-	b.ne	1b
-	st1b_unroll 0, 7
+1:	st1b_unroll 0, 7
 	add	dst, dst, tmp1
 	subs	count, count, tmp1
 	b.hi	1b