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Update bcopyb & bcopy to reflect changes I made in the libc version of
bcopy: Be smarter about handling overlapped copies and only go backwards if it is really necessary. Going backwards on a P6 is much slower than forwards and it's a little slower on a P5. Also moved the count mask and 'std' down a few lines - it's a couple percent faster this way on a P5.
This commit is contained in:
David Greenman
parent
aacd7f348e
commit
014374187c
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=13065
@ -30,7 +30,7 @@
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: support.s,v 1.28 1995/12/24 08:10:43 davidg Exp $
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* $Id: support.s,v 1.29 1995/12/26 13:58:11 bde Exp $
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*/
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#include "assym.s" /* system definitions */
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@ -206,8 +206,10 @@ bcopyb:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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cld /* nope, copy forwards */
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rep
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movsb
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@ -219,9 +221,9 @@ bcopyb:
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1:
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addl %ecx,%edi /* copy backwards. */
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addl %ecx,%esi
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std
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decl %edi
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decl %esi
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std
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rep
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movsb
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popl %edi
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@ -241,8 +243,11 @@ bcopy:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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shrl $2,%ecx /* copy by 32-bit words */
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cld /* nope, copy forwards */
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rep
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@ -259,9 +264,9 @@ bcopy:
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1:
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addl %ecx,%edi /* copy backwards */
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addl %ecx,%esi
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andl $3,%ecx /* any fractional bytes? */
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decl %edi
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decl %esi
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andl $3,%ecx /* any fractional bytes? */
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std
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rep
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movsb
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@ -30,7 +30,7 @@
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: support.s,v 1.28 1995/12/24 08:10:43 davidg Exp $
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* $Id: support.s,v 1.29 1995/12/26 13:58:11 bde Exp $
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*/
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#include "assym.s" /* system definitions */
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@ -206,8 +206,10 @@ bcopyb:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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cld /* nope, copy forwards */
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rep
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movsb
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@ -219,9 +221,9 @@ bcopyb:
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1:
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addl %ecx,%edi /* copy backwards. */
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addl %ecx,%esi
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std
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decl %edi
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decl %esi
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std
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rep
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movsb
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popl %edi
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@ -241,8 +243,11 @@ bcopy:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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shrl $2,%ecx /* copy by 32-bit words */
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cld /* nope, copy forwards */
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rep
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@ -259,9 +264,9 @@ bcopy:
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1:
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addl %ecx,%edi /* copy backwards */
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addl %ecx,%esi
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andl $3,%ecx /* any fractional bytes? */
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decl %edi
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decl %esi
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andl $3,%ecx /* any fractional bytes? */
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std
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rep
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movsb
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@ -30,7 +30,7 @@
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: support.s,v 1.28 1995/12/24 08:10:43 davidg Exp $
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* $Id: support.s,v 1.29 1995/12/26 13:58:11 bde Exp $
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*/
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#include "assym.s" /* system definitions */
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@ -206,8 +206,10 @@ bcopyb:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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cld /* nope, copy forwards */
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rep
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movsb
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@ -219,9 +221,9 @@ bcopyb:
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1:
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addl %ecx,%edi /* copy backwards. */
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addl %ecx,%esi
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std
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decl %edi
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decl %esi
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std
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rep
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movsb
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popl %edi
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@ -241,8 +243,11 @@ bcopy:
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movl 12(%esp),%esi
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movl 16(%esp),%edi
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movl 20(%esp),%ecx
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cmpl %esi,%edi /* potentially overlapping? */
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jnb 1f
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movl %edi,%eax
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subl %esi,%eax
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cmpl %ecx,%eax /* overlapping? */
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jb 1f
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shrl $2,%ecx /* copy by 32-bit words */
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cld /* nope, copy forwards */
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rep
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@ -259,9 +264,9 @@ bcopy:
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1:
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addl %ecx,%edi /* copy backwards */
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addl %ecx,%esi
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andl $3,%ecx /* any fractional bytes? */
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decl %edi
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decl %esi
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andl $3,%ecx /* any fractional bytes? */
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std
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rep
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movsb
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