RFR(XS) 8009460: C2compiler crash in machnode::in_regmask(unsigned int)

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8009460/webrev.00/

In PhaseMacroExpand::expand_allocate_common():
1- The Allocate -> MemBarStoreStore link is not broken if the graph has been transformed and the pattern matching that AllocateNode::storestore() uses cannot locate the MemBarStoreStore from the Allocate node.
2- fast_oop_rawmem is added as a precedence edge in one of the cases where a new MemBarStoreStore is created but it's not needed

Allocate -> MemBarStoreStore link is now broken during the final reshape pass from the MemBarStoreStore nodes.

Roland.