[15] RFR (M): 8237581: Improve allocation expansion

[Claes Redestad]

On 2020-01-28 12:15, Nils Eliasson wrote:
> Hi,
> 
> I added a simple micro that triggers the optimization.
> 
> Micro:
> http://cr.openjdk.java.net/~neliasso/8237581/webrev.micro/
> 
> On my workstation I get these numbers:
> 
> JDK/JDK:
> 
> Benchmark                                  (size)  Mode  Cnt Score 
> Error  Units
> ArrayAllocation.eliminateArrayConstLength     128 avgt 61.178          
> ns/op
> ArrayAllocation.eliminateArrayVarLength       128 avgt 55.109          
> ns/op
> 
> JDK/JDK + path for 8237581:
> 
> Benchmark                                  (size)  Mode  Cnt Score 
> Error  Units
> ArrayAllocation.eliminateArrayConstLength     128 avgt 0.841          ns/op
> ArrayAllocation.eliminateArrayVarLength       128 avgt 1.897          ns/op
> 
> Speedup 30-70x

Nice!

Micro looks good and to the point. I think the {}'s around "128" is
redundant for a single parameter value.

Can't really review the compiler code changes but it all looks
reasonable to me.

/Claes