When hotspot build 62/63 is built with the Windows AMD64/X64 Platform SDK (3790.1830) compiler (version 14.00.40310.41) at /O2, the build of the j2se fails. Details to follow soon.

Currently the Build 63 makefile changes in hotspot will detect this newer compiler (14.00.40310.41) and drop the optimization level from /O2 to /O1, so to build hotspot with this compiler at /O2, you will need to go into file hotspot/build/windows/makefiles/compile.make and look for the lines:

!if "$(COMPILER_NAME)" == "VS2005"
# Reduced down from /O2 because of control build failures
PRODUCT_OPT_OPTION = /O1
FASTDEBUG_OPT_OPTION = /O1
...

The above /O1 patterns needs to change to /O2.

NOTE: This 14.00.40310.41 compiler is considered a VS2005 (Visual Studio 2005) compiler. The older Platform SDK contained compiler 14.00.30701, which might appear to be VS2005 due to the "14" but is much closer to being VS2003 (13), so inside the hotspot makefiles this compiler is identified as MSC_VER=1399.

I'll add the exact circumstances of the build failure shortly... just trying to get this posted first.
FYI...

These changes did not make it into B63, they will go into B64, but they are in hotspot main/baseline.