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-rw-r--r--sysdeps/aarch64/multiarch/memset_a64fx.S9
1 files changed, 8 insertions, 1 deletions
diff --git a/sysdeps/aarch64/multiarch/memset_a64fx.S b/sysdeps/aarch64/multiarch/memset_a64fx.S
index 7bf759b6a7..f7dfdaace7 100644
--- a/sysdeps/aarch64/multiarch/memset_a64fx.S
+++ b/sysdeps/aarch64/multiarch/memset_a64fx.S
@@ -96,7 +96,14 @@ L(vl_agnostic): // VL Agnostic
L(unroll8):
sub count, count, tmp1
.p2align 4
-1: st1b_unroll 0, 7
+ // 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
add dst, dst, tmp1
subs count, count, tmp1
b.hi 1b