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

[Anton Kozlov]

On Tue, 15 Dec 2020 15:44:26 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Anton Kozlov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update pd_commit_memory on bsd
>
> 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.

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