[cpp-threads] modes, pass 2

[Doug Lea]

Alexander Terekhov wrote:
> On 5/9/05, Doug Lea <dl at cs.oswego.edu> wrote:
> 
> [... isync ...]
> 
> 
>>Even if that's so, then you should still be able to use isync
>>in combination with some form of the "if (x == x)" trick?
> 
> 
> You mean placing isync after "branch never taken"? My understaing 
> is that it (akin to B.2.3 Safe Fetch from Book II) will order only 
> load access to x with respect to subsequent loads (and stores). 
> 
> Classic #loadload is supposed to do more, oder?
> 

This may be actually good enough for nearly all practical
usages. Issues like this are why I tried going down path of "ordered"
modes, but that doesn't look promising either.

So I think everyone should try harder to find a hack that provides
cheap LoadLoad on PPC!

-Doug