From 1521237c3211bb0b1a8f7a9c5793d382789b2b68 Mon Sep 17 00:00:00 2001
From: Wilco Dijkstra <wilco.dijkstra@arm.com>
Date: Thu, 26 Oct 2023 16:34:47 +0100
Subject: [PATCH 07/26] AArch64: Cleanup emag memset

Cleanup emag memset - merge the memset_base64.S file, remove
the unused ZVA code (since it is disabled on emag).

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
(cherry picked from commit 9627ab99b50d250c6dd3001a3355aa03692f7fe5)
---
 sysdeps/aarch64/multiarch/ifunc-impl-list.c |   2 +-
 sysdeps/aarch64/multiarch/memset.c          |   2 +-
 sysdeps/aarch64/multiarch/memset_base64.S   | 185 --------------------
 sysdeps/aarch64/multiarch/memset_emag.S     |  98 +++++++++--
 4 files changed, 90 insertions(+), 197 deletions(-)
 delete mode 100644 sysdeps/aarch64/multiarch/memset_base64.S

diff --git a/sysdeps/aarch64/multiarch/ifunc-impl-list.c b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
index 836e8317a5..3596d3c8d3 100644
--- a/sysdeps/aarch64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/aarch64/multiarch/ifunc-impl-list.c
@@ -57,7 +57,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      /* Enable this on non-falkor processors too so that other cores
 		 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, (zva_size == 64), __memset_emag)
+	      IFUNC_IMPL_ADD (array, i, memset, 1, __memset_emag)
 	      IFUNC_IMPL_ADD (array, i, memset, 1, __memset_kunpeng)
 #if HAVE_AARCH64_SVE_ASM
 	      IFUNC_IMPL_ADD (array, i, memset, sve && zva_size == 256, __memset_a64fx)
diff --git a/sysdeps/aarch64/multiarch/memset.c b/sysdeps/aarch64/multiarch/memset.c
index 23fc66e158..9193b197dd 100644
--- a/sysdeps/aarch64/multiarch/memset.c
+++ b/sysdeps/aarch64/multiarch/memset.c
@@ -56,7 +56,7 @@ select_memset_ifunc (void)
   if ((IS_FALKOR (midr) || IS_PHECDA (midr)) && zva_size == 64)
     return __memset_falkor;
 
-  if (IS_EMAG (midr) && zva_size == 64)
+  if (IS_EMAG (midr))
     return __memset_emag;
 
   return __memset_generic;
diff --git a/sysdeps/aarch64/multiarch/memset_base64.S b/sysdeps/aarch64/multiarch/memset_base64.S
deleted file mode 100644
index 0e8f709fa5..0000000000
--- a/sysdeps/aarch64/multiarch/memset_base64.S
+++ /dev/null
@@ -1,185 +0,0 @@
-/* Copyright (C) 2018-2023 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>
-#include "memset-reg.h"
-
-#ifndef MEMSET
-# define MEMSET __memset_base64
-#endif
-
-/* To disable DC ZVA, set this threshold to 0. */
-#ifndef DC_ZVA_THRESHOLD
-# define DC_ZVA_THRESHOLD 512
-#endif
-
-/* Assumptions:
- *
- * ARMv8-a, AArch64, unaligned accesses
- *
- */
-
-ENTRY (MEMSET)
-
-	PTR_ARG (0)
-	SIZE_ARG (2)
-
-	bfi	valw, valw, 8, 8
-	bfi	valw, valw, 16, 16
-	bfi	val, val, 32, 32
-
-	add	dstend, dstin, count
-
-	cmp	count, 96
-	b.hi	L(set_long)
-	cmp	count, 16
-	b.hs	L(set_medium)
-
-	/* Set 0..15 bytes.  */
-	tbz	count, 3, 1f
-	str	val, [dstin]
-	str	val, [dstend, -8]
-	ret
-
-	.p2align 3
-1:	tbz	count, 2, 2f
-	str	valw, [dstin]
-	str	valw, [dstend, -4]
-	ret
-2:	cbz	count, 3f
-	strb	valw, [dstin]
-	tbz	count, 1, 3f
-	strh	valw, [dstend, -2]
-3:	ret
-
-	.p2align 3
-	/* Set 16..96 bytes.  */
-L(set_medium):
-	stp	val, val, [dstin]
-	tbnz	count, 6, L(set96)
-	stp	val, val, [dstend, -16]
-	tbz	count, 5, 1f
-	stp	val, val, [dstin, 16]
-	stp	val, val, [dstend, -32]
-1:	ret
-
-	.p2align 4
-	/* Set 64..96 bytes.  Write 64 bytes from the start and
-	   32 bytes from the end.  */
-L(set96):
-	stp	val, val, [dstin, 16]
-	stp	val, val, [dstin, 32]
-	stp	val, val, [dstin, 48]
-	stp	val, val, [dstend, -32]
-	stp	val, val, [dstend, -16]
-	ret
-
-	.p2align 4
-L(set_long):
-	stp	val, val, [dstin]
-	bic	dst, dstin, 15
-#if DC_ZVA_THRESHOLD
-	cmp	count, DC_ZVA_THRESHOLD
-	ccmp	val, 0, 0, cs
-	b.eq	L(zva_64)
-#endif
-	/* Small-size or non-zero memset does not use DC ZVA. */
-	sub	count, dstend, dst
-
-	/*
-	 * Adjust count and bias for loop. By subtracting extra 1 from count,
-	 * it is easy to use tbz instruction to check whether loop tailing
-	 * count is less than 33 bytes, so as to bypass 2 unnecessary stps.
-	 */
-	sub	count, count, 64+16+1
-
-#if DC_ZVA_THRESHOLD
-	/* Align loop on 16-byte boundary, this might be friendly to i-cache. */
-	nop
-#endif
-
-1:	stp	val, val, [dst, 16]
-	stp	val, val, [dst, 32]
-	stp	val, val, [dst, 48]
-	stp	val, val, [dst, 64]!
-	subs	count, count, 64
-	b.hs	1b
-
-	tbz	count, 5, 1f	/* Remaining count is less than 33 bytes? */
-	stp	val, val, [dst, 16]
-	stp	val, val, [dst, 32]
-1:	stp	val, val, [dstend, -32]
-	stp	val, val, [dstend, -16]
-	ret
-
-#if DC_ZVA_THRESHOLD
-	.p2align 3
-L(zva_64):
-	stp	val, val, [dst, 16]
-	stp	val, val, [dst, 32]
-	stp	val, val, [dst, 48]
-	bic	dst, dst, 63
-
-	/*
-	 * Previous memory writes might cross cache line boundary, and cause
-	 * cache line partially dirty. Zeroing this kind of cache line using
-	 * DC ZVA will incur extra cost, for it requires loading untouched
-	 * part of the line from memory before zeoring.
-	 *
-	 * So, write the first 64 byte aligned block using stp to force
-	 * fully dirty cache line.
-	 */
-	stp	val, val, [dst, 64]
-	stp	val, val, [dst, 80]
-	stp	val, val, [dst, 96]
-	stp	val, val, [dst, 112]
-
-	sub	count, dstend, dst
-	/*
-	 * Adjust count and bias for loop. By subtracting extra 1 from count,
-	 * it is easy to use tbz instruction to check whether loop tailing
-	 * count is less than 33 bytes, so as to bypass 2 unnecessary stps.
-	 */
-	sub	count, count, 128+64+64+1
-	add	dst, dst, 128
-	nop
-
-	/* DC ZVA sets 64 bytes each time. */
-1:	dc	zva, dst
-	add	dst, dst, 64
-	subs	count, count, 64
-	b.hs	1b
-
-	/*
-	 * Write the last 64 byte aligned block using stp to force fully
-	 * dirty cache line.
-	 */
-	stp	val, val, [dst, 0]
-	stp	val, val, [dst, 16]
-	stp	val, val, [dst, 32]
-	stp	val, val, [dst, 48]
-
-	tbz	count, 5, 1f	/* Remaining count is less than 33 bytes? */
-	stp	val, val, [dst, 64]
-	stp	val, val, [dst, 80]
-1:	stp	val, val, [dstend, -32]
-	stp	val, val, [dstend, -16]
-	ret
-#endif
-
-END (MEMSET)
diff --git a/sysdeps/aarch64/multiarch/memset_emag.S b/sysdeps/aarch64/multiarch/memset_emag.S
index 6fecad4fae..bbfa815925 100644
--- a/sysdeps/aarch64/multiarch/memset_emag.S
+++ b/sysdeps/aarch64/multiarch/memset_emag.S
@@ -18,17 +18,95 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sysdep.h>
+#include "memset-reg.h"
 
-#define MEMSET __memset_emag
-
-/*
- * Using DC ZVA to zero memory does not produce better performance if
- * memory size is not very large, especially when there are multiple
- * processes/threads contending memory/cache. Here we set threshold to
- * zero to disable using DC ZVA, which is good for multi-process/thread
- * workloads.
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64, unaligned accesses
+ *
  */
 
-#define DC_ZVA_THRESHOLD 0
+ENTRY (__memset_emag)
+
+	PTR_ARG (0)
+	SIZE_ARG (2)
+
+	bfi	valw, valw, 8, 8
+	bfi	valw, valw, 16, 16
+	bfi	val, val, 32, 32
+
+	add	dstend, dstin, count
+
+	cmp	count, 96
+	b.hi	L(set_long)
+	cmp	count, 16
+	b.hs	L(set_medium)
+
+	/* Set 0..15 bytes.  */
+	tbz	count, 3, 1f
+	str	val, [dstin]
+	str	val, [dstend, -8]
+	ret
+
+	.p2align 3
+1:	tbz	count, 2, 2f
+	str	valw, [dstin]
+	str	valw, [dstend, -4]
+	ret
+2:	cbz	count, 3f
+	strb	valw, [dstin]
+	tbz	count, 1, 3f
+	strh	valw, [dstend, -2]
+3:	ret
+
+	.p2align 3
+	/* Set 16..96 bytes.  */
+L(set_medium):
+	stp	val, val, [dstin]
+	tbnz	count, 6, L(set96)
+	stp	val, val, [dstend, -16]
+	tbz	count, 5, 1f
+	stp	val, val, [dstin, 16]
+	stp	val, val, [dstend, -32]
+1:	ret
+
+	.p2align 4
+	/* Set 64..96 bytes.  Write 64 bytes from the start and
+	   32 bytes from the end.  */
+L(set96):
+	stp	val, val, [dstin, 16]
+	stp	val, val, [dstin, 32]
+	stp	val, val, [dstin, 48]
+	stp	val, val, [dstend, -32]
+	stp	val, val, [dstend, -16]
+	ret
+
+	.p2align 4
+L(set_long):
+	stp	val, val, [dstin]
+	bic	dst, dstin, 15
+	/* Small-size or non-zero memset does not use DC ZVA. */
+	sub	count, dstend, dst
+
+	/*
+	 * Adjust count and bias for loop. By subtracting extra 1 from count,
+	 * it is easy to use tbz instruction to check whether loop tailing
+	 * count is less than 33 bytes, so as to bypass 2 unnecessary stps.
+	 */
+	sub	count, count, 64+16+1
+
+1:	stp	val, val, [dst, 16]
+	stp	val, val, [dst, 32]
+	stp	val, val, [dst, 48]
+	stp	val, val, [dst, 64]!
+	subs	count, count, 64
+	b.hs	1b
+
+	tbz	count, 5, 1f	/* Remaining count is less than 33 bytes? */
+	stp	val, val, [dst, 16]
+	stp	val, val, [dst, 32]
+1:	stp	val, val, [dstend, -32]
+	stp	val, val, [dstend, -16]
+	ret
 
-#include "./memset_base64.S"
+END (__memset_emag)
-- 
2.33.0

