8019247: SIGSEGV in compiled method c8e.e.t_.getArray(Ljava/lang/Class;)[Ljava/lang/Object
Summary: Undo recent changes (and add more comments) in Ideal_allocation().
Reviewed-by: roland
8006629: NEED_TEST: need test for JDK-8001071
Summary: added regression test
Reviewed-by: kvn, coleenp
Contributed-by: Filipp Zhinkin <filipp.zhinkin@oracle.com>