6944166: G1: explicit GCs are not always handled correctly Summary: G1 was not handling explicit GCs correctly in many ways. It does now. See the CR for the list of improvements contained in this changeset. Reviewed-by: iveresov, ysr, johnc

6962569: assembler_sparc.cpp:1969: assert(false) failed: error Summary: array_overlap_test() fails when the address range crosses the MSB boundary. Thanks to Tom and Vladimir for their help on this one. Reviewed-by: kvn, never, iveresov