D45623.id142467.diff
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	diff --git a/lib/libc/aarch64/string/Makefile.inc b/lib/libc/aarch64/string/Makefile.inc
	--- a/lib/libc/aarch64/string/Makefile.inc
	+++ b/lib/libc/aarch64/string/Makefile.inc
	@@ -15,11 +15,13 @@
	strchrnul \
	strcmp \
	strcpy \
	- strlen \
	strncmp \
	strnlen \
	strrchr

	+MDSRCS+= \
	+ strlen.S
	+
	#
	# Add the above functions. Generate an asm file that includes the needed
	# Arm Optimized Routines file defining the function name to the libc name.
	diff --git a/lib/libc/aarch64/string/strlen.S b/lib/libc/aarch64/string/strlen.S
	new file mode 100644
	--- /dev/null
	+++ b/lib/libc/aarch64/string/strlen.S
	@@ -0,0 +1,46 @@
	+/*-
	+ * SPDX-License-Identifier: BSD-2-Clause
	+ *
	+ * Copyright (c) 2024 Getz Mikalsen <getz@FreeBSD.org>
	+*/
	+
	+#include <machine/asm.h>
	+
	+ .weak strlen
	+ .set strlen, __strlen
	+ .text
	+
	+ENTRY(__strlen)
	+ bic x10, x0, #0xf // aligned src
	+ and x9, x0, #0xf
	+ ldr q0, [x10]
	+ cmeq v0.16b, v0.16b, #0
	+ shrn v0.8b, v0.8h, #4
	+ fmov x1, d0
	+ cbz x9, .Laligned
	+ lsl x2, x0, #2 // get the byte offset
	+ lsr x1, x1, x2 // shift by offset index
	+ cbz x1, .Lloop
	+ rbit x1, x1
	+ clz x0, x1
	+ lsr x0, x0, #2
	+ ret
	+
	+.Laligned:
	+ cbnz x1, .Ldone
	+
	+.Lloop:
	+ ldr q0, [x10, #16]!
	+ cmeq v0.16b, v0.16b, #0
	+ shrn v0.8b, v0.8h, #4 // reduce to fit mask in GPR
	+ fcmp d0, #0.0
	+ b.eq .Lloop
	+ fmov x1, d0
	+.Ldone:
	+ sub x0, x10, x0
	+ rbit x1, x1 // reverse bits as NEON has no ctz
	+ clz x3, x1
	+ lsr x3, x3, #2
	+ add x0, x0, x3
	+ ret
	+END(__strlen)