[PATCH] JDK-8176571: Fine bitmaps should be allocated as belonging to mtGC

[Milan Mimica]

Milan Mimica, Senior Software Engineer / Division Lead
> From: Kim Barrett <kim.barrett at oracle.com>
> Sent: Saturday, May 27, 2017 01:00
>
> We appreciate your interest in working on this and are happy to help, but we
> really do need to check off this process item before going any deeper.

Filled and sent.

>
> Yes, some refactoring seems required in order to properly fix JDK-8176571.
> That’s what I meant by:
>
>On May 22, 2017, at 4:41 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
>> There doesn't seem to be a good path into the functionality provided
>> by ArrayAllocator<> that has such a runtime MEMFLAGS value [...] The
>> lack of a runtime-only path for propagating that information would
>> need to be added [sic. fixed].

Okay. There are two patches.

- refactor_array_allocator.diff
Pass MEMFLAGS down to the concrete allocator via
call stack instead of using template var. Indeed it feels right, especially
because some methods don't even use MEMFLAGS.

- heapBitMap_nmt.diff
Changed CHeapBitMap to use configurable NMT pool. Changed
all (not just 'fine' bitmaps) G1 usages of CHeapBitMap to specify mtGC. Had to
add a pair CHeapBitMap constructors to make test_bitMap.cpp happy. That doesn't
feel right, but I don't know what to do, except to rewrite the test.

Btw, what are your plans on c++>=11? For example I could use delegating
constructors here, or std::is_same.
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