[jdk11u-dev] RFR: 8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses [v2]

[Fei Yang]

On Mon, 11 Sep 2023 14:29:22 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Backport to improve arm32 performance in 11u and riscv-port in: https://github.com/openjdk/riscv-port-jdk11u/pull/3.
>> This is not a clean backport as the function has been moved to new file and renamed. 
>> 
>> I checked the 11u related code and I think the following analysis on the JBS description is still true for 11u:
>> "The intrinsic is currently only implemented in C2. I see no reason for this intrinsic to depend on `UseUnalignedAccesses`: what `LibraryCallKit::inline_unsafe_allocate()` does seems similar to what the regular `Parse::do_new()` does, namely doing the clinit barrier and then delegating into `GraphKit::new_instance`."
>> 
>> Tested with the initial riscv-port in: https://github.com/openjdk/riscv-port-jdk11u/pull/3
>
> Fei Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'upstream/master' into backport-8292713
>  - 8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses

GHA is now clean. Push approval is granted.

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PR Comment: https://git.openjdk.org/jdk11u-dev/pull/2125#issuecomment-1714815635