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GNU C Library master sources branch master updated. glibc-2.28.9000-305-g5770c0a

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- Log -----------------------------------------------------------------;a=commitdiff;h=5770c0ad1e0c784e817464ca2cf9436a58c9beb7

commit 5770c0ad1e0c784e817464ca2cf9436a58c9beb7
Author: Wilco Dijkstra <>
Date:   Tue Nov 20 12:37:00 2018 +0000

    [AArch64] Adjust writeback in non-zero memset
    This fixes an ineffiency in the non-zero memset.  Delaying the writeback
    until the end of the loop is slightly faster on some cores - this shows
    ~5% performance gain on Cortex-A53 when doing large non-zero memsets.
    	* sysdeps/aarch64/memset.S (MEMSET): Improve non-zero memset loop.

diff --git a/ChangeLog b/ChangeLog
index d340866..be23442 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-11-20  Wilco Dijkstra  <>
+	* sysdeps/aarch64/memset.S (MEMSET): Improve non-zero memset loop.
 2018-11-20  Joseph Myers  <>
 	* conform/ ( Use unique identifiers
diff --git a/sysdeps/aarch64/memset.S b/sysdeps/aarch64/memset.S
index 4a45459..9738cf5 100644
--- a/sysdeps/aarch64/memset.S
+++ b/sysdeps/aarch64/memset.S
@@ -89,10 +89,10 @@ L(set_long):
 	b.eq	L(try_zva)
 	sub	count, dstend, dst	/* Count is 16 too large.  */
-	add	dst, dst, 16
+	sub	dst, dst, 16		/* Dst is biased by -32.  */
 	sub	count, count, 64 + 16	/* Adjust count and bias for loop.  */
-1:	stp	q0, q0, [dst], 64
-	stp	q0, q0, [dst, -32]
+1:	stp	q0, q0, [dst, 32]
+	stp	q0, q0, [dst, 64]!
 	subs	count, count, 64
 	b.hi	1b
@@ -183,6 +183,7 @@ L(zva_other):
 	subs	count, count, zva_len
 	b.hs	3b
 4:	add	count, count, zva_len
+	sub	dst, dst, 32		/* Bias dst for tail loop.  */
 	b	L(tail64)


Summary of changes:
 ChangeLog                |    4 ++++
 sysdeps/aarch64/memset.S |    7 ++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

GNU C Library master sources

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