On Sun, 2002-11-03 at 18:17, Denis Vlasenko wrote:
Jump target 17e0 is aligned (with nops):
> 17dd: 88 02 mov %al,(%edx)
> 17df: 90 nop
> 17e0: 89 d0 mov %edx,%eax
> 17e2: 5a pop %edx
> 17ec: eb f2 jmp 17e0 <__constant_memcpy+0x20>
> 17fa: eb e4 jmp 17e0 <__constant_memcpy+0x20>
> 1800: eb de jmp 17e0 <__constant_memcpy+0x20>
> 187c: e9 5f ff ff ff jmp 17e0 <__constant_memcpy+0x20>
> 1881: eb 0d jmp 1890 <__constant_memcpy+0xd0>
> 1883: 90 nop
...
> 188f: 90 nop
> 1890: c1 e9 02 shr $0x2,%ecx
> 1893: 89 d7 mov %edx,%edi
And also jump target 1890 is aligned.
I think the penalty of few NOPs is smaller than result of jump to
unaligned address. This is especially true with P4 architecture.
- Jussi Laako
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This archive was generated by hypermail 2b29 : Thu Nov 07 2002 - 22:00:29 EST