Perf: excess store in allocation fast path?

[Aleksey Shipilev]

On 12/06/2016 08:44 PM, Roman Kennke wrote:
> Try the attached patch. It preserves the obj_size, and passes that to
> initialize_object().

Yea, that works, see:

http://cr.openjdk.java.net/~shade/shenandoah/alloc-excess-store/alloc-shenandoah-rkennke1.txt

Compare with baseline:

http://cr.openjdk.java.net/~shade/shenandoah/alloc-excess-store/alloc-shenandoah.txt

...and have your 50 picoseconds per alloc back!

Now, I want to know if it's okay to skip zeroing memory past the allocation
pointer. I think it is safe, because that's how zeroing elimination works in
other cases?

Thanks,
-Aleksey