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8311862: RISC-V: small improvements to shift immediate instructions #14823

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@Ilyagavrilin Ilyagavrilin commented Jul 11, 2023

Please review this small change for slli srli and srai
slli change allows to replace slli Rd, Rs, 0 with addi Rd, Rs, 0 (and no operation emited if Rd == Rs)
addi with 0 has higher chances to be just a register renaming and not utilise ALU at all
We have observed small positive effect on hifive (and no change on thead).

testing: tier1 and tier2 on hifive, also hotspot/jtreg/compiler/intrinsics/string tests on Qemu with UseZba

performance on hifive, before:

Benchmark Mode Cnt Score Error Units
StringIndexOf.advancedWithShortSub1 avgt 25 4035.143 ± 191.262 ns/op
StringIndexOf.advancedWithShortSub2 avgt 25 1145.807 ± 14.610 ns/op

with patch:

Benchmark Mode Cnt Score Error Units
StringIndexOf.advancedWithShortSub1 avgt 25 3613.943 ± 178.153 ns/op
StringIndexOf.advancedWithShortSub2 avgt 25 923.169 ± 47.123 ns/op

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  • JDK-8311862: RISC-V: small improvements to shift immediate instructions (Enhancement - P4)

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bridgekeeper bot commented Jul 11, 2023

👋 Welcome back Ilyagavrilin! 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 openjdk bot added the rfr Pull request is ready for review label Jul 11, 2023
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openjdk bot commented Jul 11, 2023

@Ilyagavrilin The following label will be automatically applied to this pull request:

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When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

@openjdk openjdk bot added the hotspot hotspot-dev@openjdk.org label Jul 11, 2023
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mlbridge bot commented Jul 11, 2023

Webrevs

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@luhenry luhenry left a comment

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LGTM

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Looks good, with one nit:

if (UseZba) {
_slli_uw(Rd, Rs, shamt);
} else {
slli(Rd, Rs, shamt+32);
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Suggested change
slli(Rd, Rs, shamt+32);
slli(Rd, Rs, shamt + 32);

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Thank you for your suggestion

_slli_uw(Rd, Rs, shamt);
} else {
slli(Rd, Rs, shamt + 32);
srli(Rd, Rd, 32);
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@RealFYang RealFYang Jul 14, 2023

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I don't think this code in else block will work in the case when shamt >= 32. Note that the slli.uw instruction is the same as slli with zext.w performed on the least-significant word of Rs before shifting. So you might want to do a combination of 32-bit zero extension and slli on Rs instead.

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slli.uw with shamt >= 32 will be same as add Rd, X0, X0, isn't it ?
He can just add handling for that special case then

that was wrong.

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PS: I think we should also change the JBS title as I see this not only touches slli but also srli and srai.
Suggestion: "8311862: RISC-V: small improvements to shift immediate instructions".

@Ilyagavrilin Ilyagavrilin changed the title 8311862: RISC-V: small improvements to slli 8311862: RISC-V: small improvements to shift immediate instructions Jul 14, 2023
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Two nits remain. Looks good otherwise.

if (shamt != 0) { \
_slli(Rd, Rs1, shamt); \
} else { \
if(Rd != Rs1) { \
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Nit: s/if(Rd != Rs1) {/if (Rd != Rs1) {/

if (shamt != 0) { \
NORMAL_NAME(Rd, Rs1, shamt); \
} else { \
if(Rd != Rs1) { \
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Nit: s/if(Rd != Rs1) {/if (Rd != Rs1) {/

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openjdk bot commented Jul 14, 2023

@Ilyagavrilin 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:

8311862: RISC-V: small improvements to shift immediate instructions

Reviewed-by: luhenry, fjiang, fyang

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 49 new commits pushed to the master branch:

  • a63f865: 8311946: add support for libgraal specific jtreg tests
  • 167d1c1: 8311986: Disable runtime/os/TestTracePageSizes.java for ShenandoahGC
  • 7539cc0: 8303134: JFR: Missing stack trace during chunk rotation stress
  • d1fa1a8: 8311825: Duplicate qualified enum constants not detected
  • 4676b40: 8312049: runtime/logging/ClassLoadUnloadTest can be improved
  • bbb7ce5: 8311038: Incorrect exhaustivity computation
  • 2e12a12: 8281658: Add a security category to the java -XshowSettings option
  • 43099a8: 8311647: Memory leak in Java_jdk_internal_org_jline_terminal_impl_jna_linux_CLibraryImpl_ttyname_1r
  • c7c6d47: 6355567: AdobeMarkerSegment causes failure to read valid JPEG
  • af7f95e: 8310070: Test: javax/net/ssl/DTLS/DTLSWontNegotiateV10.java timed out
  • ... and 39 more: https://git.openjdk.org/jdk/compare/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5...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 (@luhenry, @RealFYang) 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).

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Jul 14, 2023
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/integrate

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openjdk bot commented Jul 14, 2023

@Ilyagavrilin
Your change (at version c7b0416) is now ready to be sponsored by a Committer.

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/sponsor

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openjdk bot commented Jul 14, 2023

Going to push as commit f3b96f6.
Since your change was applied there have been 49 commits pushed to the master branch:

  • a63f865: 8311946: add support for libgraal specific jtreg tests
  • 167d1c1: 8311986: Disable runtime/os/TestTracePageSizes.java for ShenandoahGC
  • 7539cc0: 8303134: JFR: Missing stack trace during chunk rotation stress
  • d1fa1a8: 8311825: Duplicate qualified enum constants not detected
  • 4676b40: 8312049: runtime/logging/ClassLoadUnloadTest can be improved
  • bbb7ce5: 8311038: Incorrect exhaustivity computation
  • 2e12a12: 8281658: Add a security category to the java -XshowSettings option
  • 43099a8: 8311647: Memory leak in Java_jdk_internal_org_jline_terminal_impl_jna_linux_CLibraryImpl_ttyname_1r
  • c7c6d47: 6355567: AdobeMarkerSegment causes failure to read valid JPEG
  • af7f95e: 8310070: Test: javax/net/ssl/DTLS/DTLSWontNegotiateV10.java timed out
  • ... and 39 more: https://git.openjdk.org/jdk/compare/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Jul 14, 2023
@openjdk openjdk bot closed this Jul 14, 2023
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Jul 14, 2023
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openjdk bot commented Jul 14, 2023

@VladimirKempik @Ilyagavrilin Pushed as commit f3b96f6.

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

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/backport jdk21u

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/backport jdk17u-dev

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@Ilyagavrilin To use the /backport command, you need to be in the OpenJDK census and your GitHub account needs to be linked with your OpenJDK username (how to associate your GitHub account with your OpenJDK username).

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@Ilyagavrilin To use the /backport command, you need to be in the OpenJDK census and your GitHub account needs to be linked with your OpenJDK username (how to associate your GitHub account with your OpenJDK username).

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