Hotspot loves PHP.reboot

[Christian Thalinger]

On Sep 6, 2011, at 5:51 PM, Charles Oliver Nutter wrote:

> On Tue, Sep 6, 2011 at 10:39 AM, Rémi Forax <forax at univ-mlv.fr> wrote:
>> Yes, but don't forget that PHP.reboot has no overflow check.
> 
> Did we ever figure out if it's possible to trick Hotspot into doing a
> JO instead of the raw bit-level operations? John/Christian/Tom: what
> would it take to get HS to "know" that we're doing an integer
> overflow-after-maths check and do the (faster?) JO?

We already talked a bit about that some while ago.  I think matching that double-xor-trick (or whatever it's called) is too risky.  A JDK method that does the check (and the math?) would be nice so we can intrinsify it.  GWT would fit here.

Btw. what means JO?

-- Christian

> 
> Rémi: For what it's worth, I did specialize +/- for 1 and 2 in the
> indy-based call protocols to avoid a full overflow check.
> 
> - Charlie
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