[cpp-threads] SC on PPC (was Re: Increment/decrement operators on atomics package)

[Raul Silvera]

Alexander Terekhov wrote on 04/30/2007 08:10:19 AM:

> How does cumulativity help in the IRIW case?
> 
> P1: x = 1;
> P2: y = 1;
> P3: r1 = x; r2 = y;
> P4: r3 = y; r4 = x;
> 

The short version of this is that cumulativity on a hwsync between the two 

loads on P3 would cause a StoreLoad ordering between P1's store to x
and P3's load of y.

Do the same for P4, plus some wild hand-waving, and you get to forbid the
disallowed IRIW outcome.

--
Raúl E. Silvera         IBM Toronto Lab         Team Lead, Toronto 
Portable Optimizer (TPO)
Tel: 905-413-4188       T/L: 969-4188           Fax: 905-413-4854 
D2/KC9/8200/MKM

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