[PATCH] AArch64: Add SVE2 strchrnul

Add an SVE2 strchrnul implementation and ifunc support based on strchr-sve.S.
Use MATCH to check for both the input char and NUL.  Performance of bench-strchrnul
improves ~34% on Neoverse V2.

There is an odd issue with HIDDEN_JUMPTARGET when building rtld - I've solved it by
switching back to plain JUMPTARGET if not in libc.

Passes check and buildmanyglibc.

Note this depends on https://sourceware.org/pipermail/libc-alpha/2026-July/179267.html.

---

diff --git a/sysdeps/aarch64/multiarch/Makefile b/sysdeps/aarch64/multiarch/Makefile
index 9f202512f1e32ddc0177d030bf295d3b7e202c1c..b85be3062eed1b6c4df109a72975ade1d37a5b73 100644
--- a/sysdeps/aarch64/multiarch/Makefile
+++ b/sysdeps/aarch64/multiarch/Makefile
@@ -18,6 +18,8 @@ sysdep_routines += \
   memset_zva64 \
   strchr_generic \
   strchr_sve2 \
+  strchrnul_generic \
+  strchrnul_sve2 \
   strlen_asimd \
   strlen_generic \
 # sysdep_routines
diff --git a/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
index 50b2581455c94dc2bd38f8e5ba9a357d1b79e89f..74fdca91baa562316f8f0a4d2450e9dd81aabb9c 100644
--- a/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
@@ -23,6 +23,8 @@ asm ("memset = __memset_generic");
 asm ("strlen = __strlen_generic");
 #ifndef SHARED
 asm ("strchr = __strchr_generic");
+asm ("strchrnul = __strchrnul_generic");
+asm ("__strchrnul = __strchrnul_generic");
 asm ("memcpy = __memcpy_generic");
 asm ("memmove = __memmove_generic");
 asm ("memcmp = __memcmp_generic");
diff --git a/sysdeps/aarch64/multiarch/ifunc-impl-list.c b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
index a0c93147c532d935d562a66ac67ebaa5326dd3bd..5f5350850dd5d8270c2675fdbdc3be0f110f7116 100644
--- a/sysdeps/aarch64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
@@ -63,5 +63,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   IFUNC_IMPL (i, name, strchr,
 	      IFUNC_IMPL_ADD (array, i, strchr, sve2 && !mte, __strchr_sve2)
 	      IFUNC_IMPL_ADD (array, i, strchr, 1, __strchr_generic))
+  IFUNC_IMPL (i, name, strchrnul,
+	      IFUNC_IMPL_ADD (array, i, strchrnul, sve2 && !mte, __strchrnul_sve2)
+	      IFUNC_IMPL_ADD (array, i, strchrnul, 1, __strchrnul_generic))
   return 0;
 }
diff --git a/sysdeps/aarch64/multiarch/strchrnul.c b/sysdeps/aarch64/multiarch/strchrnul.c
new file mode 100644
index 0000000000000000000000000000000000000000..d09508880655bada4ca9185a5cedf28714d10a31
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/strchrnul.c
@@ -0,0 +1,41 @@
+/* Multiple versions of strchrnul. AArch64 version.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* Define multiple versions only for the definition in libc.  */
+
+#if IS_IN (libc)
+/* Redefine strchrnul so that the compiler won't complain about the type
+   mismatch with the IFUNC selector in weak_alias, below.  */
+# undef strchrnul
+# undef __strchrnul
+# define strchrnul __redirect_strchrnul
+# define __strchrnul __redirect___strchrnul
+# include <string.h>
+# include <init-arch.h>
+# undef strchrnul
+# undef __strchrnul
+
+extern __typeof (__redirect_strchrnul) __strchrnul attribute_hidden;
+
+extern __typeof (__redirect_strchrnul) __strchrnul_generic attribute_hidden;
+extern __typeof (__redirect_strchrnul) __strchrnul_sve2 attribute_hidden;
+
+libc_ifunc (__strchrnul, (sve2 && !mte ? __strchrnul_sve2 : __strchrnul_generic));
+
+weak_alias (__strchrnul, strchrnul);
+#endif
diff --git a/sysdeps/aarch64/multiarch/strchrnul_generic.S b/sysdeps/aarch64/multiarch/strchrnul_generic.S
new file mode 100644
index 0000000000000000000000000000000000000000..ef11f563c318967e7ff0255a590d20d2042b6728
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/strchrnul_generic.S
@@ -0,0 +1,38 @@
+/* A Generic Optimized strchrnul implementation for AArch64.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#if IS_IN (libc)
+
+# define STRCHRNUL __strchrnul_generic
+
+/* Do not hide the generic version of strchr, we use it internally.  */
+# undef libc_hidden_def
+# define libc_hidden_def(name)
+
+# undef weak_alias
+# define weak_alias(a, b)
+
+# ifdef SHARED
+/* It doesn't make sense to send libc-internal strchr calls through a PLT. */
+	.globl __GI___strchrnul; __GI___strchrnul = __strchrnul_generic
+# endif
+#endif
+
+#include "../strchrnul.S"
diff --git a/sysdeps/aarch64/multiarch/strchrnul_sve2.S b/sysdeps/aarch64/multiarch/strchrnul_sve2.S
new file mode 100644
index 0000000000000000000000000000000000000000..3a037446d851e060790369e7ea78be8573fed56b
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/strchrnul_sve2.S
@@ -0,0 +1,22 @@
+/* Optimized strchrnul for SVE2.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#define BUILD_STRCHRNUL
+
+#include "strchr_sve2.S"
diff --git a/sysdeps/aarch64/strchrnul.S b/sysdeps/aarch64/strchrnul.S
index c80807ea73d85493982e60d023c4c137b6c9b311..6498e7cb69298bf271176dffaf50699bd43e9b5f 100644
--- a/sysdeps/aarch64/strchrnul.S
+++ b/sysdeps/aarch64/strchrnul.S
@@ -26,6 +26,10 @@
  * MTE compatible.
  */
 
+#ifndef STRCHRNUL
+# define STRCHRNUL __strchrnul
+#endif
+
 #define srcin		x0
 #define chrin		w1
 #define result		x0
@@ -50,7 +54,7 @@
    which things occur in the original string, counting leading zeros identifies
    exactly which byte matched.  */
 
-ENTRY (__strchrnul)
+ENTRY (STRCHRNUL)
 	bic	src, srcin, 15
 	dup	vrepchr.16b, chrin
 	ld1	{vdata.16b}, [src]
@@ -93,6 +97,6 @@ L(end):
 	add	result, src, tmp1, lsr 2
 	ret
 
-END(__strchrnul)
-libc_hidden_def (__strchrnul)
-weak_alias (__strchrnul, strchrnul)
+END(STRCHRNUL)
+libc_hidden_def (STRCHRNUL)
+weak_alias (STRCHRNUL, strchrnul)
diff --git a/sysdeps/aarch64/strspn.S b/sysdeps/aarch64/strspn.S
index 42f3b82a944503aa726bc8bdb61105721d0b959a..4683dfd90b3756d99c771f4da8b944d9a23274bc 100644
--- a/sysdeps/aarch64/strspn.S
+++ b/sysdeps/aarch64/strspn.S
@@ -128,7 +128,11 @@ L(early):
 	mov	w1, w2
 	mov	fp, sp
 	mov	x19, x0
-	bl	__strchrnul
+#if IS_IN(libc)
+	bl	HIDDEN_JUMPTARGET (__strchrnul)
+#else
+	bl	JUMPTARGET (__strchrnul)
+#endif
 	sub	x0, x0, x19
 	ldr	x19, [sp, 16]
 	ldp	fp, lr, [sp], 32