From 1a6cbf23692806862e883edc65e8c21986ed0c13 Mon Sep 17 00:00:00 2001
From: marius <marius@FreeBSD.org>
Date: Thu, 22 Nov 2018 16:27:30 +0000
Subject: [PATCH] MFC: r340656, MF12: r340759

Given that the idea of D15374 was to "make memmove a first class citizen",
provide a _MEMMOVE extension of _MEMCPY that deals with overlap based on
the previous bcopy(9) implementation and use the former for bcopy(9) and
memmove(9). This addresses my D15374 review comment, avoiding extra MOVs
in case of memmove(9) and trashing the stack pointer.

Approved by:	re (kib)
---
 sys/sparc64/sparc64/support.S | 77 +++++++++++++++++------------------
 1 file changed, 38 insertions(+), 39 deletions(-)

diff --git a/sys/sparc64/sparc64/support.S b/sys/sparc64/sparc64/support.S
index bba97b580a3..5b9dd68d110 100644
--- a/sys/sparc64/sparc64/support.S
+++ b/sys/sparc64/sparc64/support.S
@@ -206,6 +206,30 @@ __FBSDID("$FreeBSD$");
 	 inc	dst ; \
 6:
 
+/*
+ * Extension of _MEMCPY dealing with overlap, but unaware of ASIs.
+ * Used for bcopy() and memmove().
+ */
+#define	_MEMMOVE(dst, src, len) \
+	/* Check for overlap, and copy backwards if so. */ \
+	sub	dst, src, %g1 ; \
+	cmp	%g1, len ; \
+	bgeu,a,pt %xcc, 2f ; \
+	 nop ; \
+	/* Copy backwards. */ \
+	add	src, len, src ; \
+	add	dst, len, dst ; \
+1:	deccc	1, len ; \
+	bl,pn	%xcc, 3f ; \
+	 dec	1, src ; \
+	ldub	[src], %g1 ; \
+	dec	1, dst ; \
+	ba	%xcc, 1b ; \
+	 stb	%g1, [dst] ; \
+2:	/* Do the fast version. */ \
+	_MEMCPY(dst, src, len, EMPTY, EMPTY, EMPTY, EMPTY) ; \
+3:
+
 /*
  * void ascopy(u_long asi, vm_offset_t src, vm_offset_t dst, size_t len)
  */
@@ -265,48 +289,13 @@ ENTRY(bcmp)
 END(bcmp)
 
 /*
- * void *memmove(void *dst, const void *src, size_t len)
  * void bcopy(const void *src, void *dst, size_t len)
  */
-ENTRY(memmove)
-	/*
-	 * Swap src/dst for memmove/bcopy differences
-	 */
-	mov	%o0, %o6
-	mov	%o1, %o0
-	mov	%o6, %o1
-ALTENTRY(bcopy)
-	/*
-	 * Check for overlap, and copy backwards if so.
-	 */
-	sub	%o1, %o0, %g1
-	cmp	%g1, %o2
-	bgeu,a,pt %xcc, 3f
-	 nop
-
-	/*
-	 * Copy backwards.
-	 */
-	add	%o0, %o2, %o0
-	add	%o1, %o2, %o1
-1:	deccc	1, %o2
-	bl,a,pn	%xcc, 2f
-	 nop
-	dec	1, %o0
-	ldub	[%o0], %g1
-	dec	1, %o1
-	ba	%xcc, 1b
-	 stb	%g1, [%o1]
-2:	retl
-	 mov	%o6, %o0
-
-	/*
-	 * Do the fast version.
-	 */
-3:	_MEMCPY(%o1, %o0, %o2, EMPTY, EMPTY, EMPTY, EMPTY)
+ENTRY(bcopy)
+	_MEMMOVE(%o1, %o0, %o2)
 	retl
-	 mov	%o6, %o0
-END(memmove)
+	 nop
+END(bcopy)
 
 /*
  * void bzero(void *b, size_t len)
@@ -336,6 +325,16 @@ ENTRY(memcpy)
 	 nop
 END(memcpy)
 
+/*
+ * void *memmove(void *dst, const void *src, size_t len)
+ */
+ENTRY(memmove)
+	mov	%o0, %o3
+	_MEMMOVE(%o3, %o1, %o2)
+	retl
+	 nop
+END(memmove)
+
 /*
  * void *memset(void *b, int c, size_t len)
  */
-- 
2.45.0