RFR: 8234930: Use MAP_JIT when allocating pages for code cache on macOS [v10]

[Thomas Stuefe]

On Tue, 15 Dec 2020 17:40:39 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> src/hotspot/os/windows/os_windows.cpp line 3271:
>> 
>>> 3269: 
>>> 3270: char* os::reserve_memory_aligned(size_t size, size_t alignment, bool exec) {
>>> 3271:   // exec can be ignored
>> 
>> Change to "Support for exec not implemented" ? (Maybe even with an assert) (Or - leave that up to you - leave this parameter out of os::reserve_memory_aligned completely.)
>
> Actually, since exec and non-exec reservations are equal on windows, ignoring exec is a correct implementation. Assert would not fit here. Please let me know if the comment fails to deliver this message. Also, I have a prototype implementation of CDS support for macOS/AArch64 and it needs executable aligned mapping, I think we'll need this parameter anyway.

Okay, leave it as it is.

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