Message201675
| Author |
serhiy.storchaka |
| Recipients |
Arfrever, christian.heimes, ncoghlan, neologix, pitrou, python-dev, serhiy.storchaka, vstinner |
| Date |
2013年10月29日.21:20:05 |
| SpamBayes Score |
-1.0 |
| Marked as misclassified |
Yes |
| Message-id |
<1383081605.76.0.828443567102.issue19183@psf.upfronthosting.co.za> |
| In-reply-to |
| Content |
About memcpy(). Here is sample file. Compile it to assembler:
gcc -O2 -S -masm=intel fnv.c
With memcpy() main loop is compiled to:
.L8:
movzx ecx, BYTE PTR [ebx+edx]
imul eax, eax, 1000003
add edx, 1
xor eax, ecx
cmp edx, edi
jne .L8
With per-byte copy it is compiled to:
.L3:
mov dl, BYTE PTR [ecx]
imul eax, eax, 1000003
sub ebp, 1
movzx ebx, BYTE PTR [ecx+1]
movzx edi, BYTE PTR [ecx+2]
movzx esi, BYTE PTR [ecx+3]
add ecx, 4
mov dh, bl
sal edi, 16
movzx edx, dx
sal esi, 24
or edx, edi
or edx, esi
xor eax, edx
cmp ebp, -1
jne .L3 |
|