RFR(M): 8076188 Optimize arraycopy out for non escaping destination

[Roland Westrelin]

jprt found some problems with this change. So I’d like to push:

http://cr.openjdk.java.net/~roland/8076188/webrev.00-01/

on top of the reviewed change. Overall change:

http://cr.openjdk.java.net/~roland/8076188/webrev.01/

List of fixes:

- tests with G1 failed in verification code. I made the change to LoadNode::Ideal() so the new code that looks for a dominating identical load is disabled for raw loads

- OptimizePtrCompare is broken in cases like the new test case added to TestEliminateArrayCopy.java: field from non escaping object should have an unknown value when the the object is target of an ArrayCopy.

- The ifnode change is unrelated (I found the problem when debugging one of the issues above) but it’s simple enough that I don’t think it needs its own CR.

Roland.

> On Apr 29, 2015, at 11:30 AM, Roland Westrelin <roland.westrelin at oracle.com> wrote:
> 
> Thanks for the review, Vladimir.
> 
> Roland.
> 
>> On Apr 28, 2015, at 4:42 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
>> 
>> Looks good.
>> 
>> Best regards,
>> Vladimir Ivanov
>> 
>> On 4/21/15 4:02 PM, Roland Westrelin wrote:
>>> http://cr.openjdk.java.net/~roland/8076188/webrev.00/
>>> 
>>> This patch tries to eliminate ArrayCopyNodes (for instance clones, array clones, arraycopy and copyOf) when the destination of the copy doesn’t escape:
>>> 
>>> - during escape analysis, ArrayCopyNodes don’t cause the destination of the copy to be marked as escaping anymore
>>> - a load to the destination of a copy may be replaced by a load from the source during IGVN
>>> - during macro expansion, ArrayCopyNodes don’t stop allocation from being eliminated and can themselves be eliminated
>>> 
>>> Roland.
>>> 
>