8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses

[RealFYang]

Backport to improve arm32 performance in 11u and riscv-port in: openjdk/riscv-port-jdk11u#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: openjdk/riscv-port-jdk11u#3

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Progress

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Issue

• JDK-8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses (Enhancement - P4)

Reviewers

• Paul Hohensee (@phohensee - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u-dev.git pull/2125/head:pull/2125
$ git checkout pull/2125

Update a local copy of the PR:
$ git checkout pull/2125
$ git pull https://git.openjdk.org/jdk11u-dev.git pull/2125/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2125

View PR using the GUI difftool:
$ git pr show -t 2125

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u-dev/pull/2125.diff

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[bridgekeeper]

👋 Welcome back fyang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 01: Full - Incremental (719596c5)
• 00: Full (22895ae1)

[phohensee]

Clean backport from 17u.

[phohensee]

GHA failure is an infrastructure issue.

[openjdk]

@RealFYang This change now passes all automated pre-integration checks.

After integration, the commit message for the final commit will be:

8292713: Unsafe.allocateInstance should be intrinsified without UseUnalignedAccesses

Reviewed-by: phh

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[RealFYang]

GHA is now clean. Push approval is granted.
/integrate

[openjdk]

Going to push as commit 0713dbb.

[openjdk]

@RealFYang Pushed as commit 0713dbb.

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