8290034: Auto vectorize reverse bit operations. by jatin-bhateja · Pull Request #9535 · openjdk/jdk

jatin-bhateja · 2022-07-18T08:01:09Z

Summary of changes:

Intrinsify scalar bit reverse APIs to emit efficient instruction sequence for X86 targets with and w/o GFNI feature.
Handle auto-vectorization of Integer/Long.reverse bit operations.
Backend implementation for these were added with 4th incubation of VectorAPIs.

Following are performance number for newly added JMH mocro benchmarks:-

No-GFNI(CLX):
=============
Baseline:
Benchmark         (size)  Mode  Cnt  Score   Error  Units
Integers.reverse     500  avgt    2  1.085          us/op
Longs.reverse        500  avgt    2  1.236          us/op
WithOpt:
Benchmark         (size)  Mode  Cnt  Score   Error  Units
Integers.reverse     500  avgt    2  0.104          us/op
Longs.reverse        500  avgt    2  0.255          us/op

With-GFNI(ICX):
===============
Baseline:
Benchmark         (size)  Mode  Cnt  Score   Error  Units
Integers.reverse     500  avgt    2  0.887          us/op
Longs.reverse        500  avgt    2  1.095          us/op

Without:
Benchmark         (size)  Mode  Cnt  Score   Error  Units
Integers.reverse     500  avgt    2  0.037          us/op
Longs.reverse        500  avgt    2  0.145          us/op

Kindly review and share feedback.

Best Regards,
Jatin

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-8290034: Auto vectorize reverse bit operations.

Reviewers

Xiaohong Gong (@XiaohongGong - Committer)
Vladimir Kozlov (@vnkozlov - Reviewer) ⚠️ Review applies to 53157a29

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/9535/head:pull/9535
$ git checkout pull/9535

Update a local copy of the PR:
$ git checkout pull/9535
$ git pull https://git.openjdk.org/jdk pull/9535/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 9535

View PR using the GUI difftool:
$ git pr show -t 9535

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/9535.diff

jatin-bhateja · 2022-07-18T08:01:58Z

/label add hotspot-compiler-dev

bridgekeeper · 2022-07-18T08:02:53Z

👋 Welcome back jbhateja! 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 · 2022-07-18T08:05:00Z

@jatin-bhateja
The hotspot-compiler label was successfully added.

mlbridge · 2022-07-18T08:09:49Z

Webrevs

01: Full - Incremental (864c4d09)
00: Full (53157a29)

XiaohongGong

Common codes looks good to me. Just some style issues.

XiaohongGong · 2022-07-19T07:49:43Z

src/hotspot/share/opto/subnode.cpp

+  }
+  const TypeInt* t1int = t1->isa_int();
+  if (t1int && t1int->is_con()) {
+    jint res  = reverse_bits(t1int->get_con());


There is one more space between res = reverse_bits

XiaohongGong · 2022-07-19T07:51:07Z

src/hotspot/share/opto/subnode.cpp

+}
+
+const Type* ReverseLNode::Value(PhaseGVN* phase) const {
+  const Type *t1 = phase->type( in(1) );


The same with "ReverseINode::Value"

XiaohongGong · 2022-07-19T07:51:18Z

src/hotspot/share/opto/subnode.cpp

+  }
+  const TypeLong* t1long = t1->isa_long();
+  if (t1long->is_con()) {
+    jint res  = reverse_bits(t1long->get_con());


vnkozlov

Looks good. I submitted testing.

vnkozlov

Testing passed.

openjdk · 2022-07-21T17:05:05Z

@jatin-bhateja 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:

8290034: Auto vectorize reverse bit operations.

Reviewed-by: xgong, kvn

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 6 new commits pushed to the master branch:

348a052: 8290846: sun/tools/jstatd/JstatdTest* tests should use VM options
bc6a3c7: 8290739: Simplify storage of dump-time class information
16a1275: 8290943: Fix several IR test issues on SVE after JDK-8289801
c1a3347: 8291358: Fix the "overridding" typo
37b08c7: 8237913: G1CollectedHeap::heap_region_containing shouldn't be a template
dc74ea2: 8291048: x86: compiler/c2/irTests/TestAutoVectorization2DArray.java fails with lower SSE

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

XiaohongGong

Looks good to me! Thanks!

jatin-bhateja · 2022-07-28T04:40:47Z

/integrate

openjdk · 2022-07-28T04:43:10Z

Going to push as commit 5d82d67.
Since your change was applied there have been 6 commits pushed to the master branch:

348a052: 8290846: sun/tools/jstatd/JstatdTest* tests should use VM options
bc6a3c7: 8290739: Simplify storage of dump-time class information
16a1275: 8290943: Fix several IR test issues on SVE after JDK-8289801
c1a3347: 8291358: Fix the "overridding" typo
37b08c7: 8237913: G1CollectedHeap::heap_region_containing shouldn't be a template
dc74ea2: 8291048: x86: compiler/c2/irTests/TestAutoVectorization2DArray.java fails with lower SSE

Your commit was automatically rebased without conflicts.

openjdk · 2022-07-28T04:43:31Z

@jatin-bhateja Pushed as commit 5d82d67.

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

rose00 · 2022-08-19T06:41:29Z

src/hotspot/share/opto/subnode.cpp

  return TypeF::make( (float)sqrt( (double)f ) );
 }
+
+static jlong reverse_bits(jlong val) {


This function is wrong and/or misnamed.
It should be called reverse_bits_in_bytes.

rose00 · 2022-08-19T06:47:52Z

src/hotspot/share/opto/subnode.cpp

+  }
+  const TypeInt* t1int = t1->isa_int();
+  if (t1int && t1int->is_con()) {
+    jint res = reverse_bits(t1int->get_con());


This is clearly wrong, if I understand correctly that ReverseI is an intrinsic for Integer::reverse, which reverses not only bits in bytes but also the bytes themselves.

Also, it seems noxious (IIUC) because it widens t1int's con to 64 bits with sign extension, does some sort of 64-bit reversal operation, and then chops off the high order bits assigning to res.

The root cause here is that reverse_bits should be properly factored out and maintained in its own modular header file, akin to utilities/powerOfTwo.hpp. I suggest utilities/moveBits.hpp, to hold bits-in-bytes reversal, byte reversal, full reversal, compress/expand (with which it should be grouped) and who knows what other future permutations.

I say it's a root cause in that something randomly coded in the bowels of subnode.cpp cannot be properly reviewed in isolation, especially if it is misnamed.

Also, the nearly identical use of the HD algorithm in code/compressedStream.cpp should use the new version in the header file.

The new hand-written assembly code for this changeset should refer the reader to utilities/moveBits.hpp as well.

Jatin Bhateja added 2 commits July 18, 2022 00:29

8290034: Auto vectorize reverse bit operations.

00d6811

8290034: Adding descriptive comments.

53157a2

openjdk bot added rfr Pull request is ready for review hotspot-compiler hotspot-compiler-dev@openjdk.org labels Jul 18, 2022

XiaohongGong reviewed Jul 19, 2022

View reviewed changes

vnkozlov reviewed Jul 20, 2022

View reviewed changes

vnkozlov approved these changes Jul 21, 2022

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label Jul 21, 2022

Jatin Bhateja added 2 commits July 27, 2022 08:42

8290034: Styling comments resolved.

80af86c

Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8290034

864c4d0

XiaohongGong approved these changes Jul 28, 2022

View reviewed changes

openjdk bot added the integrated Pull request has been integrated label Jul 28, 2022

openjdk bot closed this Jul 28, 2022

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jul 28, 2022

rose00 reviewed Aug 19, 2022

View reviewed changes

jatin-bhateja deleted the JDK-8290034 branch January 20, 2023 21:26

Conversation

jatin-bhateja commented Jul 18, 2022 • edited by openjdk bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Progress

Issue

Reviewers

Reviewing

Uh oh!

jatin-bhateja commented Jul 18, 2022

Uh oh!

bridgekeeper bot commented Jul 18, 2022

Uh oh!

openjdk bot commented Jul 18, 2022

Uh oh!

mlbridge bot commented Jul 18, 2022 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Webrevs

Uh oh!

XiaohongGong left a comment

Choose a reason for hiding this comment

Uh oh!

XiaohongGong Jul 19, 2022

Choose a reason for hiding this comment

Uh oh!

XiaohongGong Jul 19, 2022

Choose a reason for hiding this comment

Uh oh!

XiaohongGong Jul 19, 2022

Choose a reason for hiding this comment

Uh oh!

vnkozlov left a comment

Choose a reason for hiding this comment

Uh oh!

vnkozlov left a comment

Choose a reason for hiding this comment

Uh oh!

openjdk bot commented Jul 21, 2022 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

XiaohongGong left a comment

Choose a reason for hiding this comment

Uh oh!

jatin-bhateja commented Jul 28, 2022

Uh oh!

openjdk bot commented Jul 28, 2022

Uh oh!

openjdk bot commented Jul 28, 2022

Uh oh!

rose00 Aug 19, 2022

Choose a reason for hiding this comment

Uh oh!

rose00 Aug 19, 2022

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Milestone

Development

Uh oh!

4 participants

jatin-bhateja commented Jul 18, 2022 •

edited by openjdk bot

Loading

mlbridge bot commented Jul 18, 2022 •

edited

Loading

openjdk bot commented Jul 21, 2022 •

edited

Loading