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Fix a minor nit that has been bugging me for a while. Fix the obvious

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cases of using a 64 bit operation to zero a register.  32 bit opcodes are
smaller and supposedly faster, and clear the upper 32 bits for free.
This commit is contained in:
peter 2005-09-27 18:32:46 +00:00
parent 257c4e0863
commit 78d1baf100
2 changed files with 12 additions and 12 deletions
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2
sys/amd64/amd64/cpu_switch.S
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@ -155,7 +155,7 @@ ENTRY(cpu_switch)
smsw %ax
orb $CR0_TS,%al
lmsw %ax
xorq %rax,%rax
xorl %eax,%eax
movq %rax,PCPU(FPCURTHREAD)
1:

22
sys/amd64/amd64/support.S
View File

@ -59,7 +59,7 @@ eintrnames:
/* done */
ENTRY(bzero)
movq %rsi,%rcx
xorq %rax,%rax
xorl %eax,%eax
shrq $3,%rcx
cld
rep
@ -74,7 +74,7 @@ ENTRY(bzero)
ENTRY(pagezero)
movq $-PAGE_SIZE,%rdx
subq %rdx,%rdi
xorq %rax,%rax
xorl %eax,%eax
1:
movnti %rax,(%rdi,%rdx)
movnti %rax,8(%rdi,%rdx)
@ -256,7 +256,7 @@ ENTRY(copyout)
movsb
done_copyout:
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rdx
movq %rax,PCB_ONFAULT(%rdx)
ret
@ -301,7 +301,7 @@ ENTRY(copyin)
movsb
done_copyin:
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rdx
movq %rax,PCB_ONFAULT(%rdx)
ret
@ -412,7 +412,7 @@ ENTRY(fubyte)
ALIGN_TEXT
fusufault:
movq PCPU(CURPCB),%rcx
xorq %rax,%rax
xorl %eax,%eax
movq %rax,PCB_ONFAULT(%rcx)
decq %rax
ret
@ -432,7 +432,7 @@ ENTRY(suword)
ja fusufault
movq %rsi,(%rdi)
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rcx
movq %rax,PCB_ONFAULT(%rcx)
ret
@ -446,7 +446,7 @@ ENTRY(suword32)
ja fusufault
movl %esi,(%rdi)
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rcx
movq %rax,PCB_ONFAULT(%rcx)
ret
@ -460,7 +460,7 @@ ENTRY(suword16)
ja fusufault
movw %si,(%rdi)
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rcx /* restore trashed register */
movq %rax,PCB_ONFAULT(%rcx)
ret
@ -475,7 +475,7 @@ ENTRY(subyte)
movl %esi, %eax
movb %al,(%rdi)
xorq %rax,%rax
xorl %eax,%eax
movq PCPU(CURPCB),%rcx /* restore trashed register */
movq %rax,PCB_ONFAULT(%rcx)
ret
@ -522,7 +522,7 @@ ENTRY(copyinstr)
/* Success -- 0 byte reached */
decq %rdx
xorq %rax,%rax
xorl %eax,%eax
jmp cpystrflt_x
3:
/* rdx is zero - return ENAMETOOLONG or EFAULT */
@ -569,7 +569,7 @@ ENTRY(copystr)
/* Success -- 0 byte reached */
decq %rdx
xorq %rax,%rax
xorl %eax,%eax
jmp 6f
4:
/* rdx is zero -- return ENAMETOOLONG */