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

Roland Westrelin roland.westrelin at oracle.com
Tue Apr 21 18:09:09 UTC 2015

Thanks Vladimir for reviewing this.

> Good.  Nice work.
> CallLeafNode::may_modify() - does arraycopy call have dest in different edges? Why you searching through inputs fro it?

Stubs that can be called once an ArrayCopyNode is expanded have different signatures:

// arraycopy stub variations:                                                                                                                                                                                                                                                   
enum ArrayCopyType {
  ac_fast,                      // void(ptr, ptr, size_t)                                                                                                                                                                                                                       
  ac_checkcast,                 //  int(ptr, ptr, size_t, size_t, ptr)                                                                                                                                                                                                           
  ac_slow,                      // void(ptr, int, ptr, int, int)                                                                                                                                                                                                                 
  ac_generic                    //  int(ptr, int, ptr, int, int)                                                                                                                                                                                                                 


> Thanks,
> Vladimir
> On 4/21/15 6:02 AM, 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.

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