RFR: 8296231: Fix MEMFLAGS for CHeapBitMaps

[Thomas Stuefe]

On Wed, 2 Nov 2022 14:24:07 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> Some usages of CHeapBitMaps rely on the default value of the MEMFLAGS argument (mtInternal). This is undesirable, and should be fixed.
> 
> I'd prefer to remove the default value, but there is currently a PR touching the BitMap classes, so I'd like to limit this Bug to only fixing the incorrect usage of mtInternal.

> I think it is unclear if this would be a net benefit for the code base. IMHO, it's easier to mess up by forgetting to add a MemFlagsMark, than if the compiler straight up told you that you need to provide a MEMFLAGS. It's also harder to look at a CHeap allocating call-site and figure out where the MemFlagsMark is located.

> This looks reasonable. I vote no on a MemFlagsMark - we have too many Mark things that are hard to explain where to put them.

No problem. It's good we talked about it before I sunk work into this.

Cheers, Thomas

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PR: https://git.openjdk.org/jdk/pull/10948