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Christian Franke wrote:
> Pavel Roskin wrote:
>   
>> On Tue, 2008-07-08 at 20:04 +0200, Christian Franke wrote:
>>
>>     
>>> With old gcc versions without the "rol" optimization, even the 16
>>> bit swap should be a function:
>>>
>>>       
>> Or better yet, an asm statement.
>>
>> We should consider optimized assembly vs function call.  Even the
>> 32-bit swap could be shorter:
>>
>> a:   86 c4                   xchg   %al,%ah
>> c:   c1 c0 10                rol    $0x10,%eax
>> f:   86 c4                   xchg   %al,%ah
>> 11:
>>
>> That's 7 bytes!  ...
>>     
>
> But the function call in the 32-bit case requires only 5 bytes :-)
>   

Sorry, I was wrong here. The assumption about function call size was 
only true for module-local calls. If a module calls a function in 
kernel, each 5 byte call requires another 8 bytes for the ELF relocation 
table entry.

Christian