d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

amd64: depessimize userspace memcpy/memmove/bcopy

Browse Source 
The change resembles what was done in r334537 for kernel routines.
While here take care of i386 variants. Note that primitives remain
suboptimal.

Reviewed by:	kib (previous version)
Approved by:	re (gjb)
Differential Revision:	https://reviews.freebsd.org/D17167
This commit is contained in:
mjg 2018-09-17 15:49:35 +00:00
parent ffdf9cafeb
commit 7864c480b1
2 changed files with 16 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
lib/libc/amd64/string/bcopy.S
View File

@ -66,6 +66,9 @@ ENTRY(bcopy)
movsq
movq %rdx,%rcx
andq $7,%rcx /* any bytes left? */
jne 2f
ret
2:
rep
movsb
ret
@ -73,11 +76,13 @@ ENTRY(bcopy)
addq %rcx,%rdi /* copy backwards. */
addq %rcx,%rsi
std
andq $7,%rcx /* any fractional bytes? */
decq %rdi
decq %rsi
andq $7,%rcx /* any fractional bytes? */
je 3f
rep
movsb
3:
movq %rdx,%rcx /* copy remainder by words */
shrq $3,%rcx
subq $7,%rsi

13
lib/libc/i386/string/bcopy.S
View File

@ -64,7 +64,7 @@ ENTRY(bcopy)
movl %edi,%edx
subl %esi,%edx
cmpl %ecx,%edx /* overlapping? */
jb 1f
jb 2f
cld /* nope, copy forwards. */
movl %ecx,%edx
shrl $2,%ecx /* copy by words */
@ -72,21 +72,28 @@ ENTRY(bcopy)
movsl
movl %edx,%ecx
andl $3,%ecx /* any bytes left? */
jne 1f
popl %edi
popl %esi
ret
1:
rep
movsb
popl %edi
popl %esi
ret
1:
2:
addl %ecx,%edi /* copy backwards. */
addl %ecx,%esi
std
movl %ecx,%edx
andl $3,%ecx /* any fractional bytes? */
decl %edi
decl %esi
andl $3,%ecx /* any fractional bytes? */
je 3f
rep
movsb
3:
movl %edx,%ecx /* copy remainder by words */
shrl $2,%ecx
subl $3,%esi