[Bug c/43782] Erroneous expansion of __asm__() directive

[pinskia at gmail dot com]

------- Comment #6 from pinskia at gmail dot com  2010-04-19 15:07 -------
Subject: Re:  Erroneous expansion of __asm__() directive



Sent from my iPhone

On Apr 19, 2010, at 7:35 AM, "Nelson H. F. Beebe"  
<beebe@math.utah.edu> wrote:

>>> That is wrong because with AT&T style x86 asm, the src is first  
>>> and the dest is
>>> second.
>
> That cannot be the case: you cannot change the operand order after  
> three
> years of it working one way!

It did not change. Just what happened was gcc is now inlining the  
function. Before it was not inlining the function which allowed the  
inline-asm's two operands to be the same (the argument to the function  
and the return value are done in the same register). Which means you  
were just getting lucky that it worked. In fact AT&T asm has always  
been that way; while intel style asm is the opposite. Gcc outputs AT&T  
by default, though you can change it via an option.


>
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43782