AArch64: Add memset_zva64

Add a specialized memset for the common ZVA size of 64 to avoid the
overhead of reading the ZVA size.  Since the code is identical to
__memset_falkor, remove the latter.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
(cherry picked from commit 3d7090f14b)

sysdeps/aarch64/memset.S

@@ -101,19 +101,19 @@ L(tail64):
 	ret
 
 L(try_zva):
-#ifdef ZVA_MACRO
+#ifndef ZVA64_ONLY
-	zva_macro
-#else
 	.p2align 3
 	mrs	tmp1, dczid_el0
 	tbnz	tmp1w, 4, L(no_zva)
 	and	tmp1w, tmp1w, 15
 	cmp	tmp1w, 4	/* ZVA size is 64 bytes.  */
 	b.ne	 L(zva_128)
-
+	nop
+#endif
 	/* Write the first and last 64 byte aligned block using stp rather
 	   than using DC ZVA.  This is faster on some cores.
 	 */
+	.p2align 4
 L(zva_64):
 	str	q0, [dst, 16]
 	stp	q0, q0, [dst, 32]
@@ -123,7 +123,6 @@ L(zva_64):
 	sub	count, dstend, dst	/* Count is now 128 too large.	*/
 	sub	count, count, 128+64+64	/* Adjust count and bias for loop.  */
 	add	dst, dst, 128
-	nop
 1:	dc	zva, dst
 	add	dst, dst, 64
 	subs	count, count, 64
@@ -134,6 +133,7 @@ L(zva_64):
 	stp	q0, q0, [dstend, -32]
 	ret
 
+#ifndef ZVA64_ONLY
 	.p2align 3
 L(zva_128):
 	cmp	tmp1w, 5	/* ZVA size is 128 bytes.  */

sysdeps/aarch64/multiarch/Makefile

@@ -12,10 +12,10 @@ sysdep_routines += \
   memmove_mops \
   memset_a64fx \
   memset_emag \
-  memset_falkor \
   memset_generic \
   memset_kunpeng \
   memset_mops \
+  memset_zva64 \
   strlen_asimd \
   strlen_generic \
 # sysdep_routines

sysdeps/aarch64/multiarch/ifunc-impl-list.c

@@ -54,9 +54,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      IFUNC_IMPL_ADD (array, i, memmove, mops, __memmove_mops)
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_generic))
   IFUNC_IMPL (i, name, memset,
-	      /* Enable this on non-falkor processors too so that other cores
+	      IFUNC_IMPL_ADD (array, i, memset, (zva_size == 64), __memset_zva64)
-		 can do a comparative analysis with __memset_generic.  */
-	      IFUNC_IMPL_ADD (array, i, memset, (zva_size == 64), __memset_falkor)
 	      IFUNC_IMPL_ADD (array, i, memset, 1, __memset_emag)
 	      IFUNC_IMPL_ADD (array, i, memset, 1, __memset_kunpeng)
 #if HAVE_AARCH64_SVE_ASM

sysdeps/aarch64/multiarch/memset.c

@@ -28,7 +28,7 @@
 
 extern __typeof (__redirect_memset) __libc_memset;
 
-extern __typeof (__redirect_memset) __memset_falkor attribute_hidden;
+extern __typeof (__redirect_memset) __memset_zva64 attribute_hidden;
 extern __typeof (__redirect_memset) __memset_emag attribute_hidden;
 extern __typeof (__redirect_memset) __memset_kunpeng attribute_hidden;
 extern __typeof (__redirect_memset) __memset_a64fx attribute_hidden;
@@ -47,18 +47,17 @@ select_memset_ifunc (void)
     {
       if (IS_A64FX (midr) && zva_size == 256)
 	return __memset_a64fx;
-      return __memset_generic;
     }
 
   if (IS_KUNPENG920 (midr))
     return __memset_kunpeng;
 
-  if ((IS_FALKOR (midr) || IS_PHECDA (midr)) && zva_size == 64)
-    return __memset_falkor;
-
   if (IS_EMAG (midr))
     return __memset_emag;
 
+  if (zva_size == 64)
+    return __memset_zva64;
+
   return __memset_generic;
 }
 

sysdeps/aarch64/multiarch/memset_falkor.S

@@ -1,54 +0,0 @@
-/* Memset for falkor.
-   Copyright (C) 2017-2022 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>
-#include <memset-reg.h>
-
-/* Reading dczid_el0 is expensive on falkor so move it into the ifunc
-   resolver and assume ZVA size of 64 bytes.  The IFUNC resolver takes care to
-   use this function only when ZVA is enabled.  */
-
-#if IS_IN (libc)
-.macro zva_macro
-	.p2align 4
-	/* Write the first and last 64 byte aligned block using stp rather
-	   than using DC ZVA.  This is faster on some cores.  */
-	str	q0, [dst, 16]
-	stp	q0, q0, [dst, 32]
-	bic	dst, dst, 63
-	stp	q0, q0, [dst, 64]
-	stp	q0, q0, [dst, 96]
-	sub	count, dstend, dst	/* Count is now 128 too large.	*/
-	sub	count, count, 128+64+64	/* Adjust count and bias for loop.  */
-	add	dst, dst, 128
-1:	dc	zva, dst
-	add	dst, dst, 64
-	subs	count, count, 64
-	b.hi	1b
-	stp	q0, q0, [dst, 0]
-	stp	q0, q0, [dst, 32]
-	stp	q0, q0, [dstend, -64]
-	stp	q0, q0, [dstend, -32]
-	ret
-.endm
-
-# define ZVA_MACRO zva_macro
-# define MEMSET __memset_falkor
-# include <sysdeps/aarch64/memset.S>
-#endif

sysdeps/aarch64/multiarch/memset_zva64.S

@@ -0,0 +1,27 @@
+/* Optimized memset for zva size = 64.
+   Copyright (C) 2023 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>
+
+#define ZVA64_ONLY 1
+#define MEMSET __memset_zva64
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(X)
+
+#include "../memset.S"