C2: Compiler scheduling oddity

Aleksey Shipilev aleksey.shipilev at oracle.com
Thu Jun 16 16:14:40 UTC 2016


On 06/16/2016 06:38 PM, Andrew Haley wrote:
> Later, the blocks containing the load and the store are merged, but
> there is nothing to stop the store from rising above the load, and
> occasionally it does.

This sounds bad. Shouldn't we re-check anti-dependencies during local
scheduling?

> So, it's clear to me what is happening, but how to fix it?  I don't
> know why this doesn't happen all the time.  Does any of this sound
> familiar?

I wonder if you can reliably reproduce it with -XX:+StressLCM (and maybe
-XX:+StressGCM too).

Thanks,
-Aleksey

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