RFR: 8234930: Use MAP_JIT when allocating pages for code cache on macOS

Tue Sep 29 07:15:38 UTC 2020

On Mon, 28 Sep 2020 11:17:49 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> @tstuefe My patch to remove MAP_FIXED from the memory reservation path should make it possible to revert all the
> os::reserve_memory changes in this patch.

FWIW, I now understand that the motivation for the changes in os::reserve_memory is *not* that *it* uses MAP_FIXED.
Instead the change there is done so that os::commit_memory doesn't have to mix mmap + MAP_FIXED + MAP_JIT. This is also
the reason why os::uncommit_memory needs to be changed as well. So, ignore my comment above.

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PR: https://git.openjdk.java.net/jdk/pull/294