Please help. extended asm syntax unclearly documented.

[Richard Henderson]

On Mon, Dec 16, 2002 at 01:51:24PM +0100, Carlo Wood wrote:
>    The use of 'rep' garantees that after this assembly code
>    %ecx equals to 0.  But how to tell gcc that?

You can't.

>   How can I tell gcc that only that specific range is
>   clobbered?

 "=m"(structure).

Using gcc's variable sized structure extensions, you can
get something sized appropriately, but that's not going to 
do any good.  If the object is not fixed sized, you might 
as well just use the "memory" clobber -- it's all the same
in the end anyway.

>   It seems that they forgot to add "cc", and I don't understand

For backward compatibility, the x86 backend automatically
adds this.

>   why they added the '&' in "=&c" and "=&D" in this case :(.

It is unnecessary.



r~