8295276: AArch64: Add backend support for half float conversion intrinsics

[Bhavana-Kilambi]

This patch adds aarch64 backend support for library intrinsics that implement conversions between half-precision and single-precision floats.

Ran the following benchmarks to assess the performance with this patch -

org.openjdk.bench.java.math.Fp16ConversionBenchmark.floatToFloat16 org.openjdk.bench.java.math.Fp16ConversionBenchmark.float16ToFloat

The performance (ops/ms) gain with the patch on an ARM NEON machine is shown below -

  Benchmark                                      Gain
  Fp16ConversionBenchmark.float16ToFloat         3.42
  Fp16ConversionBenchmark.floatToFloat16         5.85

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8295276: AArch64: Add backend support for half float conversion intrinsics

Reviewers

• Nick Gasson (@nick-arm - Reviewer)
• Andrew Haley (@theRealAph - Reviewer)
• Ningsheng Jian (@nsjian - Committer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/10796/head:pull/10796
$ git checkout pull/10796

Update a local copy of the PR:
$ git checkout pull/10796
$ git pull https://git.openjdk.org/jdk pull/10796/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 10796

View PR using the GUI difftool:
$ git pr show -t 10796

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/10796.diff

[bridgekeeper]

👋 Welcome back bkilambi! 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]

@Bhavana-Kilambi The following label will be automatically applied to this pull request:

• hotspot-compiler

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[mlbridge]

Webrevs

• 00: Full (121f543c)

[Bhavana-Kilambi]

Could anyone please take a look at this PR and give their feedback ? Thank you ..

[nick-arm]

Looks OK to me but needs another review.

[openjdk]

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

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

8295276: AArch64: Add backend support for half float conversion intrinsics

Reviewed-by: ngasson, aph, njian

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 394 new commits pushed to the master branch:

• 45d1807: 6312651: Compiler should only use verified interface types for optimization
• bcc6b12: 8296945: PublicMethodsTest is slow due to dependency verification with debug builds
• fc61658: 8294591: Fix cast-function-type warning in TemplateTable
• 544e317: 8059632: Method reference compilation uses incorrect qualifying type
• 651e547: 8297217: Incorrect generation name in the heap verification log message with Serial GC
• dd55310: 8297303: ProblemList java/awt/Mouse/EnterExitEvents/DragWindowTest.java on macosx-all
• 3ea8971: 8269817: serviceability/jvmti/DynamicCodeGenerated/DynamicCodeGeneratedTest.java timed out with -Xcomp
• 0a3b0fc: 8296784: Provide clean mallinfo/mallinfo2 wrapper for Linux glibc platforms
• 7b3d581: 8297293: Add java/nio/channels/FileChannel/FileExtensionAndMap.java to ProblemList
• 251e065: 8296764: NMT: reduce loads in os::malloc
• ... and 384 more: https://git.openjdk.org/jdk/compare/9b971626f79b4f64442cf6888c2b6114c9a06351...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@nick-arm, @theRealAph, @nsjian) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[nsjian]

Looks good to me.

[Bhavana-Kilambi]

/integrate

[openjdk]

@Bhavana-Kilambi
Your change (at version 121f543) is now ready to be sponsored by a Committer.

[nsjian]

/sponsor

[openjdk]

Going to push as commit 891c706.
Since your change was applied there have been 395 commits pushed to the master branch:

• 3c09498: 8297241: Update sun/java2d/DirectX/OnScreenRenderingResizeTest/OnScreenRenderingResizeTest.java
• 45d1807: 6312651: Compiler should only use verified interface types for optimization
• bcc6b12: 8296945: PublicMethodsTest is slow due to dependency verification with debug builds
• fc61658: 8294591: Fix cast-function-type warning in TemplateTable
• 544e317: 8059632: Method reference compilation uses incorrect qualifying type
• 651e547: 8297217: Incorrect generation name in the heap verification log message with Serial GC
• dd55310: 8297303: ProblemList java/awt/Mouse/EnterExitEvents/DragWindowTest.java on macosx-all
• 3ea8971: 8269817: serviceability/jvmti/DynamicCodeGenerated/DynamicCodeGeneratedTest.java timed out with -Xcomp
• 0a3b0fc: 8296784: Provide clean mallinfo/mallinfo2 wrapper for Linux glibc platforms
• 7b3d581: 8297293: Add java/nio/channels/FileChannel/FileExtensionAndMap.java to ProblemList
• ... and 385 more: https://git.openjdk.org/jdk/compare/9b971626f79b4f64442cf6888c2b6114c9a06351...master

Your commit was automatically rebased without conflicts.

[openjdk]

@nsjian @Bhavana-Kilambi Pushed as commit 891c706.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.