Comment #6 on issue 436 by [email protected]: Numeric results are wrong on  
some systems due to x87 extended double precision
http://code.google.com/p/v8/issues/detail?id=436

> The impact of extended-precision results [...] seems to be minimal,
> and any intrusive changes to solve this problem would cause
> performance hits. Should this be marked as "will not fix", or "fixed"?


The Caja group is designing an enforced-deterministic subset of Cajita, for  
use for replicated
computations -- both for high availability under partition as well as low  
latency query operations
(as would benefit the planned Caja embeddings in Wave). Such deterministic  
replayability also
benefits security <http://www.eecs.berkeley.edu/~finifter/pure-ccs08.pdf>  
and recreation
(imagine <http://fantasticcontraption.net/> in Cajita). With the exception  
of this floating point
issue, we believe that an enhanced Cajita rewriting strategy can enforce  
all the remaining
determinism issues at reasonable cost.

However, if the basic floating point operations are not of a deterministic  
precision, we have been
unable to invent any other means of recovering affordable determinism by  
rewriting.

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