From b895ae5b59f7ef26e055a29a17f276194be4e670 Mon Sep 17 00:00:00 2001
From: phk <phk@FreeBSD.org>
Date: Wed, 4 Oct 1995 15:58:57 +0000
Subject: Calling sbrk(2) with zero argument doesn't need to generate a
 syscall.

Reviewed by:	bde
---
 lib/libc/amd64/sys/sbrk.S | 14 ++++++++++----
 lib/libc/i386/sys/sbrk.S  | 14 ++++++++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

(limited to 'lib/libc')

diff --git a/lib/libc/amd64/sys/sbrk.S b/lib/libc/amd64/sys/sbrk.S
index b0324ae..2d65b59 100644
--- a/lib/libc/amd64/sys/sbrk.S
+++ b/lib/libc/amd64/sys/sbrk.S
@@ -33,12 +33,12 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: sbrk.S,v 1.1 1994/08/05 01:18:49 wollman Exp $
+ *	$Id: sbrk.S,v 1.2 1995/01/23 01:30:04 davidg Exp $
  */
 
 #if defined(SYSLIBC_RCS) && !defined(lint)
 	.text
-	.asciz "$Id$"
+	.asciz "$Id: sbrk.S,v 1.2 1995/01/23 01:30:04 davidg Exp $"
 #endif /* SYSLIBC_RCS and not lint */
 
 #include "SYS.h"
@@ -61,6 +61,8 @@ ENTRY(sbrk)
 	movl	PIC_GOT(curbrk),%edx
 	movl	(%edx),%eax
 	PIC_EPILOGUE
+	testl	%ecx,%ecx
+	jz	back
 	addl	%eax,4(%esp)
 	lea	SYS_brk,%eax
 	LCALL(7,0)
@@ -70,21 +72,25 @@ ENTRY(sbrk)
 	movl	(%edx),%eax
 	addl	%ecx,(%edx)
 	PIC_EPILOGUE
+back:
 	ret
 err:
 	jmp	PIC_PLT(cerror)
 
-#else
+#else /* !PIC */
 
 	movl	4(%esp),%ecx
 	movl	curbrk,%eax
+	testl	%ecx,%ecx
+	jz	back
 	addl	%eax,4(%esp)
 	lea	SYS_brk,%eax
 	LCALL(7,0)
 	jb	err
 	movl	curbrk,%eax
 	addl	%ecx,curbrk
+back:
 	ret
 err:
 	jmp	cerror
-#endif
+#endif /* PIC */
diff --git a/lib/libc/i386/sys/sbrk.S b/lib/libc/i386/sys/sbrk.S
index b0324ae..2d65b59 100644
--- a/lib/libc/i386/sys/sbrk.S
+++ b/lib/libc/i386/sys/sbrk.S
@@ -33,12 +33,12 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: sbrk.S,v 1.1 1994/08/05 01:18:49 wollman Exp $
+ *	$Id: sbrk.S,v 1.2 1995/01/23 01:30:04 davidg Exp $
  */
 
 #if defined(SYSLIBC_RCS) && !defined(lint)
 	.text
-	.asciz "$Id$"
+	.asciz "$Id: sbrk.S,v 1.2 1995/01/23 01:30:04 davidg Exp $"
 #endif /* SYSLIBC_RCS and not lint */
 
 #include "SYS.h"
@@ -61,6 +61,8 @@ ENTRY(sbrk)
 	movl	PIC_GOT(curbrk),%edx
 	movl	(%edx),%eax
 	PIC_EPILOGUE
+	testl	%ecx,%ecx
+	jz	back
 	addl	%eax,4(%esp)
 	lea	SYS_brk,%eax
 	LCALL(7,0)
@@ -70,21 +72,25 @@ ENTRY(sbrk)
 	movl	(%edx),%eax
 	addl	%ecx,(%edx)
 	PIC_EPILOGUE
+back:
 	ret
 err:
 	jmp	PIC_PLT(cerror)
 
-#else
+#else /* !PIC */
 
 	movl	4(%esp),%ecx
 	movl	curbrk,%eax
+	testl	%ecx,%ecx
+	jz	back
 	addl	%eax,4(%esp)
 	lea	SYS_brk,%eax
 	LCALL(7,0)
 	jb	err
 	movl	curbrk,%eax
 	addl	%ecx,curbrk
+back:
 	ret
 err:
 	jmp	cerror
-#endif
+#endif /* PIC */
-- 
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